Author Topic: Speakers for dry organ installations  (Read 13094 times)

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pwhodges

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Speakers for dry organ installations
« on: October 08, 2010, 12:46:25 AM »
This topic was being discussed in a couple of threads on the Hauptwerk forum until David was banned there.  At that point I had just made a long post as the result of some careful thought going back to first principles; I am copying that post here (essentially unedited) because I would be interested in David's reaction to it, and to give him the opportunity to continue the discussion a little.  In summary, for those who don't want to read it all, I believe that David's criticism of the use of many types of speaker in organ installations is justified, but that he gives the wrong reasons for it, and this both colours people's reactions to his criticism and fails to direct him towards a clear explanation of his solutions.

Quote from: pwhodges on the Hauptwerk forum
First, a story. When I was a student, in the 1960s, some friends of mine who are now famous (as far as specialists in arcane areas of audio can be) for their work in (among other things) psychoacoustics, did some investigations into the realism attained using different stereo miking techniques. They played differently miked test recordings of the same performance to various people. The interesting result was that people who knew little about sound reproduction said that they thought one performance was better than the other - because they could hear a difference, and couldn't think of another way to express it.

I think that David is falling into the same trap, and as a result he ends up describing things wrongly even though he starts from the right point. This mismatch of perception is what has been annoying me, and I'd like to put it right.

I work (in my audio hobby, that is) generally in the areas of recording and reproduction - in 3D as it happens, using ambisonics. My aim in reproducing a recording is to play it back in such a way as to reconstruct the original sound field that the microphone has captured in such a way as to encompass the listener's head. This (though more exacting) is pretty much what most people playing back stereo recordings are aiming for as well. In particular, it leads to a requirement for minimal additional contribution from the listening room, and so, as well as making this rather dead, we design speakers so that the direct radiation in the direction of the listener has a flat response; other directions can go hang, so long as they do not have such prominent peaks or troughs that the (minimal) reverberation in the listening room becomes coloured. This leads to the typical design of a hi-fi speaker or near-field monitor (they are not fundamentally different) - and is not anything to do with being designed for pop music or anything like that, which is what David has been saying that irritated me so much!

PA systems have to deal with trying to get clarity across in places which inevitably have more reverberation than a typical domestic setting. They do this by going for directionality as far as possible, to minimise the excitation of the reverberation, and to gain the greatest signal to reverberation ratio at the listener's head that they can manage. The requirements are in fact similar to those above, but the space available allows the use of more extreme techniques, such as line sources, to increase directionality beyond what can be managed from a single box.

Now, if we consider the case of playing the sound of a pipe, recorded dry, in an auditorium, the requirements are quite different - we want to excite the acoustic, and we want to do it similarly to how a pipe would do it, that is, by radiating sound somewhat uniformly in all directions in order to get a similar build-up of reverberation. (The output of a pipe, or any other instrument, is decidedly not uniform in all directions - but attempting to model that non-uniformity is a lost cause with currently conceivable technology, even if a speaker per pipe was provided.) So we are looking, ideally, for speakers that radiate omnidirectionally, which is clearly a requirement deliberately not aimed for by hi-fi speakers, monitors, or PA systems - so David has good reason for saying that those are unsuitable, though the reason is not that which he gives (see story above). The response of a pseudo-omnidirectional speaker may also not be flat in any specific direction (as I suspect David has also observed), because what we would like to be flat is actually the power response integrated over all directions (parallel compromises can be seen in omnidirectional microphones designed for use in the diffuse field). Omnidirectional speakers are extremely difficult to make, because any sensibly sized speaker is large enough to act as a baffle at the higher frequencies (at 10kHz, an obstacle of only an inch or two's width is already significant); but there are techniques which enable one to get a bit closer to the ideal, and I have no doubt that David is using some of them.

I just think it would make life easier if he would (a) recognise what he is aiming for in engineering terms, so that he can use language that actually addresses the issues, and (b) tell us what he is doing, because once the issues are recognised, it will be seen that there is nothing magic about it - just solutions to a defined engineering problem.

Paul
« Last Edit: October 08, 2010, 12:50:02 AM by pwhodges »

David Pinnegar

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Re: Speakers for dry organ installations
« Reply #1 on: October 08, 2010, 01:52:12 AM »
Dear Paul

THANKS so much for coming along to continue this discussion as I think we're like minded in considering that the issues have great validity. As in many people's minds an organ is an organ, whether pipe or electronic, bad electronics give organs a bad impression among people who don't know otherwise. Therefore encouraging electronic organs to present the organ as the exciting instrument that it is worthy of the name is important for pipe organs.

Those who worry that good electronics will do bad things for pipe organ builders need not worry as pipe organs score on longevity. That is not the issue here, but for that reason, it's good to look academically at how the final interface in an electronic organ's speech can be improved. For many who simple want the answer to the question "what shall I buy - and it had better be expensive as it's my status symbol" :-) philosphy of speaker design is tedious. However, it's very worthy of consideration.

I'm very much looking forward to giving your posting and thoughts the attention they deserve, but a friend has come around to dinner this evening so I'm otherwise distracted.

For those who like after dinner stories (forums can sometimes be too serious, and organs should be fun) and who are wondering what "dry organ installations" mean, it does not refer to the famous eccentric Italian organist the late Giorgio Questa who built a portable pipe organ only to be engaged at San Fruttuoso di Camogi at Genova, accessible only by boat. He refused to take his pipe organ on the boat in case the boat was eaten by sharks and the concert had to be cancelled. Such an organ would not be a wet organ!

Here, it simply means recording organ pipes note by note and replaying them via computer memory either with the original reverberation of the building, a wet acoustic, or without the reverberation at the end of each note, so as if a "dry" acoustic.

In the other forum there appeared to be a consensus that possibly different design criteria might be necessary for
(a) reproducing an organ with its original acoustic as if a hi-fi recording of the organ in its original place at home - this is really great as with the numbers of "sample sets" of organs being recorded around the world becoming available, one can experience the spirit of instruments that otherwise one would never have the opportunity to play
(b) reproducing an organ "dry" so that the speakers become the organ whether at home or in a larger installation - and for home use, the immediacy of a "dry" instrument, as if a pipe organ in one's room, allows much more critical and serious practice.

On another thread here I have posted a suggestion that the area of speakers might usefully relate to the area of pipework in use (whether pipe diameters or mouth areas). ForumAdmin may combine these posts in due course if relevant.

Paul - please forgive me for additionally setting the scene for newcomers to the discussion, and I hope that whilst nourishing mental capacity you might forgive the non-immediacy of my reply. In the meantime, it will be great to see if others have ideas to throw into the melting pot.

Best wishes

David P


Holditch

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Re: Speakers for dry organ installations
« Reply #2 on: October 08, 2010, 03:53:21 AM »
I am fairly new to world of electronic organs and their reproduction, but I have quite a lot of experience with regards to loudspeakers and audio systems having been working in the commercial and professional audio world for nearly 20 years now.

The major problem in my opinion with a conventional loudspeaker is that it is pistonic and not like an instrument (for example violin or piano string). This in my mind is the first major downfall with regards to trying to reproduce an acoustic instrument like a pipe organ through electronic means and conventional loudspeakers.

The company that I work for has recently built up a relationship with Amina, who make flat panel sound transducers, which are nothing like the conventional piston speaker we all know about (whose design has not fundamentally changed in 80 or 90 years). I have a couple of their sound panels and intend to try them with an electronic organ signal to see how they work. In case you have not heard of the sound panel (pioneered by NXT), it uses a honeycomb structure and an exciter or exciters. It reproduces sound like a violin and is omni directional. The propagation of sound is completely different and the way it interacts with its surroundings is completely different to a normal loudspeaker

One of the downfalls of the panel is its inability to produce bass like a conventional piston loudspeaker, however I am intrigued to see how the remaining frequencies are reproduced and will be letting you know.

For more information on the technology, please see http://www.amina.co.uk

Just thought I would add a new twist to these discussions


Marc
Dubois is driving me mad! must practice practice practice

David Pinnegar

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Re: Speakers for dry organ installations
« Reply #3 on: October 08, 2010, 06:17:58 AM »
I believe that David's criticism of the use of many types of speaker in organ installations is justified, but that he gives the wrong reasons for it, and this both colours people's reactions to his criticism and fails to direct him towards a clear explanation of his solutions.

Dear Paul

Thanks. I may not necessarily be able to answer this evening and might take your post in a number of parts in a series of replies, as there is a lot.

Firstly, as I understand life and possibly life reflected in forums as they should be, I admire most the people who are senior in their field and who say that they learn something new every day. This can only be achieved by way of openness of interaction and willingness to discuss. No-one holds the right answers to everything and, where one has a group of experienced and learned people, if there is a point to discussion, it is progress and that will only be achieved in the spirit of a university tutorial in which people are happy to bounce ideas around the group.

For this reason I am most grateful to you for point out flaws in my processes.

Quote
They played differently miked test recordings of the same performance to various people. The interesting result was that people who knew little about sound reproduction said that they thought one performance was better than the other - because they could hear a difference, and couldn't think of another way to express it.

There are times when we take great care over something and so we _think_ that the result must be better. I found this the other day where on my organ, I took great care to get the sound I wanted on an en chamade trumpet and on a cromorne by using a combination of two interesting speakers, one of which an exotic vintage unit I had to import from America, for one channel serving the bass end and another combination of what I thought to be milder units, one to my design, for the upper keyboard octaves. On account of a loose connection the other day, I tested one channel against the other and, they sounding virtually the same, I wondered why I had gone to the trouble I had . . . So I understand entirely where you are coming from.

Quote
I work (in my audio hobby, that is) generally in the areas of recording and reproduction - in 3D as it happens, using ambisonics. My aim in reproducing a recording is to play it back in such a way as to reconstruct the original sound field that the microphone has captured in such a way as to encompass the listener's head.


WOW!

Quote
In particular, it leads to a requirement for minimal additional contribution from the listening room, and so, as well as making this rather dead, we design speakers so that the direct radiation in the direction of the listener has a flat response; other directions can go hang, so long as they do not have such prominent peaks or troughs

That is a rather interesting observation and it has been confirmed for decades since pre-quadraphonic attempts at simulating the rear wave for which experiments it was known that the back speakers needed not to be of critical quality. This has particular relevance for people engaged in seriously multi-channel surround sound . . . in which possibly the fashion may be to have all the speakers, including the rear, exactly the same and thereby unnecessarily expensive? However, I have not taken an interest in such systems so please update me if I'm wrong.

Quote
This leads to the typical design of a hi-fi speaker or near-field monitor (they are not fundamentally different) - and is not anything to do with being designed for pop music or anything like that, which is what David has been saying that irritated me so much!

We may discuss this privately in due course - there is a flaw in conventional monitors, especially two way monitors, which may make them more acceptable for certain types of music.

Quote
PA systems have to deal with trying to get clarity across in places which inevitably have more reverberation than a typical domestic setting. They do this by going for directionality as far as possible, to minimise the excitation of the reverberation, and to gain the greatest signal to reverberation ratio at the listener's head that they can manage. The requirements are in fact similar to those above, but the space available allows the use of more extreme techniques, such as line sources, to increase directionality beyond what can be managed from a single box.

This is exceedingly interesting and something that probably few of us have appreciated.

Quote
Now, if we consider the case of playing the sound of a pipe, recorded dry, in an auditorium, the requirements are quite different - we want to excite the acoustic, and we want to do it similarly to how a pipe would do it, that is, by radiating sound somewhat uniformly in all directions in order to get a similar build-up of reverberation.


Agreed. In my instrument I have used some speakers enclosed at the back but others open. One designer of a major Hauptwerk installation on which I gave some advice has taken a similar approach but in a slightly different way. With a difficult Giegen Diapason on the Swell of the ex-Londonderry Cathedral instrument, I found the best sound came from a near open baffle design enclosure mounted at 45 degrees and the front wave bouncing off a ceiling surface around a metre in front.

Of course that has implications at the bass end . . . but it works to my advantage as from memory the wisdom of EOCS members of around 20 years ago was that one could tell an electronic organ a mile off from a certain heaviness in the 100 Hz region. Therefore making one's speaker response light in this region, achieved well with an open design, works to advantage.

Quote
The response of a pseudo-omnidirectional speaker may also not be flat in any specific direction (as I suspect David has also observed)

Again I think this works to advantage of realism.

Quote
what we would like to be flat is actually the power response integrated over all directions

Clearly to achieve an overall balance generally. No response in any point of a room is flat anyway on account of interference patterns.

Quote
but there are techniques which enable one to get a bit closer to the ideal, and I have no doubt that David is using some of them.

:-)

Essentially where one is achieving a reproductive realism of organ plus acoustic of somewhere else, one must use speakers that are as flat and pure as possible, to recreate that environment as hi-fi. One of my favourite speakers is the 1961 design Kef K1, although currently these are in the barn. One only has to look at these
http://www.kef.com/Resources/KEFUnits/A%20History%20of%20Kef%20Drive%20Units%20-%20Issue%202.pdf

to see why, with that massive bass unit, they'd be rather good for organ reproduction.

In contrast when one looks at a speaker of today
http://www.musik-service.de/mackie-hr-824-mk-2-prx395760652en.aspx one sees a small woofer, actively driven and the details comment how this produces extra bass within a rather small cabinet. This means that the woofer excursion distance is going to have to be significantly greater and that therefore the unit will be having to travel faster. (Paul - I'm putting this in terms for non specialists!) In doing so, imagine an ambulance siren going backwards and forwards in front of your ears, the Doppler effect changing the pitch of whatever else emerges. So when one has any note up to about 150Hz at a high level, any other notes being forced through that woofer rather than the static tweeter are going to be shaken around, backwards and forwards, so changing frequency on every cycle of the low note. For this reason the unit will be unaccountably muddy and not sound natural.

The most natural sounding speakers will be ones where designers have made special efforts to minimise transducer movement and I do this in one way, as clearly Marc's panel speakers do in another (Marc - THANK YOU for contributing to this discussion - your post is very fascinating) and as Quad Electrostatics did with significantly large surface area.

However, another circumstance of organ reproduction is that of "dry" samples where the speakers represent the pipes. Here it depends how one allocates speakers to pipes and when I took on the Londonderry instrument it was apparent that one of the engineers had thought carefully about which sort of standard stock speaker for which sorts of stops and made a start at allocating them. This was a clue from which I subsequently worked and realised that one did not need a powered speaker with woofer to which more boost was given represent a 2ft rank starting at about 250Hz and nor did I need that stop broken as it went up the keyboard between different units. When one applies a speaker suitable to the nature of stop it is reproducing it will sound so much more real than a speaker designed to be all things to all men.

It's for that reason that I took significant time on the other forum to get people to _think_ of, if they want their organ to perform rather than simply be a keyboard controlled hi-fi system, how their organ would want to speak, how their "pipes" would be speaking, and thereby to consider their instrument in terms of an electroacoustic analogue of the pneumoacoustic pipe.

In doing so the results can be so much more successful than mere software, however clever, can achieve alone. For those, however, for whom software is the paragon of life, daring to suggest that the acoustic interface can have an influence upon the output of their product appears to be a taboo and a terrible affront.

It's for this sort of reason that is universal to all human groups from time to time that I wrote the posting about tuning herecies in times past
http://www.organmatters.co.uk/index.php?topic=189.0
leading one to be burned at the stake for suggesting that one might tune an instrument to play in more than the then permitted keys :) and no doubt uttering a few herecies in the process for good measure.  ;D Thank goodness for freedoms of thought and speech!

Best wishes

David P 

« Last Edit: October 08, 2010, 06:19:35 AM by David Pinnegar »

David Pinnegar

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Re: Speakers for dry organ installations
« Reply #4 on: October 08, 2010, 02:42:06 PM »
The major problem in my opinion with a conventional loudspeaker is that it is pistonic and not like an instrument (for example violin or piano string). This in my mind is the first major downfall with regards to trying to reproduce an acoustic instrument like a pipe organ through electronic means and conventional loudspeakers.

The company that I work for has recently built up a relationship with Amina, who make flat panel sound transducers, which are nothing like the conventional piston speaker we all know about (whose design has not fundamentally changed in 80 or 90 years).  In case you have not heard of the sound panel (pioneered by NXT), it uses a honeycomb structure and an exciter or exciters. It reproduces sound like a violin and is omni directional.

Dear Marc

Really interesting. However, some musical instruments do have a pistonic analogue, in particular wind instruments. Percussion is another thing . . . and it's obvious that one cannot get the full sound of a 15 inch cymbal out of a 1 inch tweeter. So a flat panel wave transducer will be a much better model for that as well as all instruments with an acoustic soundboard.

When I was at school a great friend who I have not heard of since turned up with some sort of "speaker" to be used on boats. It was very heavy, presumably on account of the magnet, about 6-8 inches in diameter from which a great stubby woodcrew emerged. It screwed into a wooden panel or plasterboad wall and . . . was rather good. Has anyone heard of such a device in modern times? Does anyone know what it might have been?

I'd love to hear your panels and try them against other means of achieving large accoustic areas.

Best wishes

David P

revtonynewnham

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Re: Speakers for dry organ installations
« Reply #5 on: October 08, 2010, 03:09:41 PM »
Hi

Another interesting topic!

We do need, however, to make a distinction between producing music (i.e. generating an appropriate sound filed in a given room for an electronic organ) and REproducing music, where the aim is to reflect (or sometimes improve) on a live performance. 

In the case of designing a room for reproduction, then acoustics need to be on the dead side, so that they do not overwhelm the acoustic on the recording, whilst in the sound production area, the room acoustics generally need to be somewhat liver and the distribution of reflections, etc will have a significant effect on the final sound.  Artificial reverberation also attempts this trick.

As to speaker, flat panels are not a new development as such - Quad electrostatic speakers are of the flat panel genre, and have been around for over 50 years - and they make a very good sound, albeit somewhat bass light and with limited power handling capability. I have heard one of the panels described above - but only on a stand in a busy exhibition, so I can't really comment on how effective it is (or isn't).  Again experiments have been going on in this area, using electro-magnetic drivers, for a number of years.

Every Blessing

Tony

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Re: Speakers for dry organ installations
« Reply #6 on: October 08, 2010, 05:06:39 PM »
Recently "de-classified" Magneto-restrictive materials, used in submarines, are now turning up in "speaker" designs...  but this for the average person falls into the category of "unobtanium" :(
at least for now.

As for my "in-home" sound "re" production facility it has taken more than a few iterations to take the  crossovers,  amplifiers, wire and speakers available to me (meaning what I had "on-hand") and arrange them to produce a workable result-- where having been to a particular venue and heard the organ "live and direct" and the same organ recorded,  played back, modulated, transmitted, received, demodulated, amplified and finally presented to my speakers,  I had only to make a minor adjustment to the level driving the infinite baffle subwoofer to get the frequency response balance right. 

It was truly amazing how much music I was missing having made the changes to approximate convincingly the experience of being someplace and listening to a pipe organ... Everything sounds much more "alive"... The CD collection numbers over a hundred, and of a large variation in music genre...  Moreover I have cabling arranged to bring audio directly from any of the computer soundcards into the  "reproduction" system  so listening to any of David's productions can be experienced to the fullest possible notwithstanding the limitations of digital compression and the dynamic range of the soundcard or the software driving it...  That "balloon detonation" demo David put together (and I have also heard the 1812 overture which proceeded it 8) was certainly FUN here...

Eric
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David Pinnegar

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Re: Speakers for dry organ installations
« Reply #7 on: October 08, 2010, 06:21:25 PM »
  That "balloon detonation" demo David put together (and I have also heard the 1812 overture which proceeded it 8) was certainly FUN here...

 :) Glad you enjoyed it - for anyone new to this it's on
http://www.jungleboffin.com/mp4/organ/hugh-potton-1/mp3-6-1st-encore-beware.mp3
and if any organist would like to have fun in such a way, audiences are asking me when we will be doing such a thing again - so performers with a glint in their eye are very welcome!

Seriously, your setup sounds very interesting - how many channels are you using and if you are using rear channels how do you arrange them for mere Stereo CDs?

One of the reasons for my interest in the speaker issue is that there are many people contemplating installing software based organ installations at home and I hear many comments about the cost being too high, not only with respect to the primary software and computer requirements but also to speakers.

Not only there are circumstances where people think that multiple speakers are _necessary_ - there being a distinction between necessity and desire, but often people think that speakers have to cost a lot of money.

In spending a lot of money, sometimes people get things which are arguably less compatible with the pipes they are reproducing than they might be, and spending that money unnecessarily, the cost becomes an unnecessary barrier to the home organ installation project. Of course it's horses for courses and Tony sums it up well:
Quote
We do need, however, to make a distinction between producing music (i.e. generating an appropriate sound filed in a given room for an electronic organ) and REproducing music, where the aim is to reflect (or sometimes improve) on a live performance. 

An acquaintance who demoed a high profile software organ for the EOCS in the summer using wet samples, for which hi-fi reproduction is required, but tailored more specifically to organs, has modified a pair of  Celestion Ditton 200 speakers bought on eBay and for less than £150 has a system that sounds very clear and interesting.

It's not surprising that the Hauptwerk software developers and those in awe of their software did not like my contributions to discussion in suggesting that speakers of the nature that they liked to recommend at 6 times the cost http://www.studiospares.com/studio-monitors/mackie-hr824-mkii-pair-2pt/invt/260930/ were the Emperor's New Clothes as far as organs were concerned - I'm not unique in making such observations:
http://www.dogsonacid.com/showthread.php?threadid=570199
Quote
If you make hip hop or DnB and like to also check out your mixes on a P/A system or a ghetto blaster, it's something you might want because they have that sound, but I'm an audiophile ****** and strongly prefer genuine accuracy when it comes to the low-end).

They also have crossover phasing issues. When I was demoing monitors I thought that the upper-mid-range was a bit iffy, and it was interesting to learn that their crossover was around 1900hz, and that the low-freqs out of the crossover are delayed more than the hi freqs - and the passive radiator just makes it worse.

Don't get me wrong: I wouldn't say they sound bad, but just that they don't sound like monitors at all to me.

I had experienced this with speakers of a similar nature when involved in a record production this year. A female singer's gutteral consonants were being reproduced by the "monitors" as sibilant clicks accompanied by a disembodied vocal tone.

That discussion board is interesting as it showed how people assumed that a current commercial offering to the market must of course be better than one from 4 years ago . . . It was in this vein that I deliberately chose the first ever 1961 KEF design as an example of good speakers . . .

Taking care not to simply follow the fashion and believing the sales talk http://beatitdo1324.org/?p=105 but instead to _think_ about what one's system needs to do is so worthwhile, achieving top results at lower cost into the bargain, and you have clearly achieved that!

Best wishes

David P
« Last Edit: October 08, 2010, 06:26:33 PM by David Pinnegar »

pwhodges

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Re: Speakers for dry organ installations
« Reply #8 on: October 08, 2010, 07:45:24 PM »
Quote
In particular, it leads to a requirement for minimal additional contribution from the listening room, and so, as well as making this rather dead, we design speakers so that the direct radiation in the direction of the listener has a flat response; other directions can go hang, so long as they do not have such prominent peaks or troughs

That is a rather interesting observation and it has been confirmed for decades since pre-quadraphonic attempts at simulating the rear wave for which experiments it was known that the back speakers needed not to be of critical quality. This has particular relevance for people engaged in seriously multi-channel surround sound . . . in which possibly the fashion may be to have all the speakers, including the rear, exactly the same and thereby unnecessarily expensive?

My remarks were about the off-axis radiation of the front speakers; to the extent that the listening room is dry, it doesn't matter what it is like - but listening rooms are not completely dry, so of course the better designers do not ignore it. 

In addition there is a difference between "surround sound" as commonly practised, in which some woofly noises are sent to the rear speakers to give some semblance of envelopment,  and using rear speakers to reproduce the sounds from that direction as accurately as the sounds from the front are reproduced, which is what I do - this naturally calls for identical speakers all round.

Quote
Quote
The response of a pseudo-omnidirectional speaker may also not be flat in any specific direction (as I suspect David has also observed)

Again I think this works to advantage of realism.

We should not be using defects in the speaker to add their own character to the sound; this character should be in the original sample (or simulation if the sound is being modelled).

Quote
... the Doppler effect changing the pitch of whatever else emerges. So when one has any note up to about 150Hz at a high level, any other notes being forced through that woofer rather than the static tweeter are going to be shaken around, backwards and forwards, so changing frequency on every cycle of the low note. For this reason the unit will be unaccountably muddy and not sound natural.

In fact this is not Doppler effect, but phase modulation (but as they are related, this is nit-picking!  In the same vein, it is incorrect to call this a distortion because it is a linear effect, even though undesired).  More to the point, there is a lot of waffle about it, and precious few calculations and measurements.  In fact, at hi-fi levels it is pretty much insignificant.  It is probably largely insignificant for organs too, because the high levels of very low frequencies are generated by very large woofer cones which (a) are probably moving no faster than the smaller cones of petite speakers which cut off higher, and (b) will simply not be capable of reproducing frequencies high enough to be noticeably affected, and so won't be called on to do so.

Quote
The most natural sounding speakers will be ones where designers have made special efforts to minimise transducer movement

This leads on to the matter of multi-driver systems and crossovers. 

There have been single-cone loudspeakers that professed to cover the full range of hearing, but usually this was actually a rather truncated range; there are speakers with multiple cones attached to one voice-coil - which in effect use a mechanical crossover, which can only be less well defined than an electrical one.  In general, multiple drivers are used to cover the full range satisfactorily.  There are various problems that arise as a result; good design can minimise these for hi-fi and monitoring use both of which require good on-axis performance more than anything else.  However, when considering the off-axis performance, problems appear.  For any driver on a baffle of a certain size, the output will become more directional as the frequency gets higher; there may also be a substantial change in directivity at the point of crossing over.  Also, below a certain frequency the output drops because of an effect known as the baffle step (this can be corrected in the crossover, of course).  All this is already making our aim of an omnidirectional speaker a bit of a nonsense - but there's more!  If the drivers are not perfectly coincidental (as in Tannoy dual-concentric drivers, for instance), there will be comb filtering effects as we move off the axis of the speaker.  Actually, we're quite lucky that our hearing is tolerant enough to let us get away with all this at all.

Another technique that is used to minimise speaker cone movement is reflex loading.  If not well-designed, this can have dreadful effects, but well done* it is a perfectly acceptable technique to reduce cone movement around resonance.

I am not a speaker designer (and I have to go and do other things right now, and will be out this evening), but this should give a taste of the considerations involved.  I may come back with more tomorrow.

Paul

* This BBC report describes the design of the monitor speakers which I use at home; I have six of them...
« Last Edit: October 08, 2010, 07:48:22 PM by pwhodges »

dragonser

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Re: Speakers and Samples
« Reply #9 on: October 08, 2010, 08:14:23 PM »
Hi,
well I think that if you are using Organ samples with a lot of reverb already present on them, then using headphones would be the best way of listening to the sounds.
Otherwise the Reverb on the samples may clash with the reverb/ sound of the room you are in.
and you would need to ( I think ) be careful with speaker placement as having the speakers in the front of the room means that you get all the sound ( main signal + reverb ) from only two points in the front direction, plus the small amount of Reverb from the back of the room.

regards Peter B




An acquaintance who demoed a high profile software organ for the EOCS in the summer using wet samples, for which hi-fi reproduction is required, but tailored more specifically to organs, has modified a pair of  Celestion Ditton 200 speakers bought on eBay and for less than £150 has a system that sounds very clear and interesting.

 
Best wishes

David P

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Re: Speakers for dry organ installations
« Reply #10 on: October 08, 2010, 08:26:53 PM »
Hmmmm... "Rear" is somewhat subjective.  I guess if one is facing the television (pulled from a dumpster, fixed a new "mains" cord to where the original was cut to render it inoperative, thus restoring to full functionality... Using the THX (R) optimizer on a DVD the video checks out as so close to perfect I don't dare mess with the controls so as to make it worse 8))  then the rear channel pair is buried into a recessed space where I primarily store surplus electronics and have the computers arranged. (The "dining" room ;) One of the speakers is only about two feet to the right from where I currently sit typing this all up.  This pair of Accusound speakers was GIVEN to me, (8 inch 'woofer' plus dome tweeter,
the 10 inch passive radiator long gone after foam surround breakdown) and is operated without the
passive radiator.  Interesting interior construction with much baffling forming a form of "folded horn" for the rear of the 8 inch woofer to "work against" if you will...  They may suffer in the bottom range as a result but as that pair runs on its own PA driven by a 12 band equaliser fed from the four-output active "low-level" subwoofer crossover network (few bucks used pawn-shop special-- no power supply, but I had tons of "wall-warts" that would do the trick in the junquepile) and thus uses its highest frequency output pair  point as the source.

This is where things get tricky... The 'main' listening space comprises the living room, dining room, and kitchen and forms an "L" shaped space, with a "cathedral" style ceiling in the Kitchen/living room area, and a much lower ceiling here in the "dining" room area.  Facing the television (audio for this appliance uses the same speaker system) this "dining" area is behind.

 (As discovered a year ago after viewing some of your Youtube posts and messing about with some FFT software on a computer connected to cheap-but-effective microphones, the whole of this space has a fundamental resonant frequency of roughly 4 Hz...)

To make this acoustical nightmare more interesting a fireplace of brick construction is placed right smack in the center of the space splitting the kitchen and living room, and to the observer's Left if looking into the television screen.  On either side of the fireplace chimney are bookshelves built into
this elevated space and run nearly clear to the ceiling... It is into one of these spaces I placed one of a pair of "cheap" studio monitors, fed with "left" channel audio... facing away from the chimney and firing into the MDF-panelled wall opposite, thus reflecting audio back into the living room and to some degree the kitchen.   The "right" speaker in this pair sits atop the equipment rack, also facing the same wall, and away from the listener positioned to look at the television.

And so we now have to fill the acoustical "hole" in our intended listening space created by the kitchen... and in there are a pair of  what  I would best describe as some form of autosound monstrosity ostensibly designed to provide a great deal of bass but on account of the cheap drivers originally fitted failed miserably in that respect, and also equipped with piezoelectric horn tweeters...

In my "installation" each unit is series-parallel wired with an additional 6X9 two-way speaker to help with midrange and boost high-frequency lacking in the pair of horn tweeters installed in the other cabinets...  and the original drivers replaced with what Radio Shack calls a "subwoofer"... In reality, it is actually a "ruggedized" version of what they have been selling for years and calling a "woofer"... model CFSW104... long since discontinued... I bought the last of them on closeout... around $20.00 a unit...   In a bass-reflex or similar loaded enclosure, a very hard-to-kill unit but will bottom easily in  infinite-baffle service if given enough power.  Tapped appropriately is another pair of speaker cable running into a bathroom adjacent to the kitchen feeding a pair of Kenwood pickup truck speakers...

All of this is series wired with the "front" pair in the living room...  and are fed from a Radio Shack two-channel  "PA service" power amplifier, at 100 Watts per channel.  My only complaint with this amplifier is some audible mains hum... so will have to crack the case on that one day and see what could be done to minimize that, likely replace the filter capacitors which may now be nearing the end of their lives... or replace with a similar output automotive amplifier and power it from the Amateur Radio Service equipment uninteruptible 12VDC supply...

Each pair of speakers is wired with the left channel to the left as you face the speakers...

Behind the rack which contains the power amplifiers, equalizer, crossover network, CD changer,
DAT machine, DVD player, tape machine switch (DBX 400X) and Tascam 102 cassete deck, is a corner of the room, and doorway leading to a bedroom, and fitted into the door are four 12 inch
subwoofers driven from their own amplifier via the subwoofer crossover network, with the bedroom
serving as the "loss space" for the infinite-baffle subwoofer.  With the amplifier I am using, (another
pawn-shop "u-fix" special which worked fine when I got it home and tested it) the subwoofer develops 115dB SPL at one meter measured with the Radio Shack digital SPL meter, C-weighted,
more drive level causes the internal protection circuit in the amplifier to activate, thus shutting itself off until the drive level drops to something less demanding and resets.  This is especially evident when the input frequency falls below 20Hz and the speaker impedance will thus drop like a rock causing additional load.     At "sane" levels this setup allows one to truly experience the pedal department of organs in much the manner as one experiences in the concert hall-- the notes are felt as much or more than heard.  Single-pane window glass is thus visibly affected... and although the other bedrooms with the doors open function as "bass traps" I usually leave them open as they tend to rattle in their frames if closed 8)  and this trapping only really affects bass  levels in the
kitchen space anyway...  Another IB formed between the bathroom and kitchen would likely solve that problem and reinforce the bottom end in there as well  ;)

An audiophile friend of mine who has heard the system audition "Pomp and Pipes" has commented that considering the money invested  that it does a respectable job of audio reproduction, and actually wants a friend of his who IS a "big dollar" audiophile to give it a listen...

As far as obtaining multiple speakers "on the cheap" for filling out the sound of a virtual pipe organ,
one should seriously consider looking to the second-hand market and even consider supporting the
operation of a number of charitable organizations who raise money by selling donated goods, of which some intriguing high-fidelity equipment of days gone by can be had for very little money.

Even if drivers are found to be worn or blown,  time  and money can be saved by removing the drivers and recycling the cabinetry and using these for experimentation or evaluation... Especially if the shop space and tool inventory required to build your own speaker enclosures is lacking.

So, to summarize... Two channel system,  with an active subwoofer crossover network through which everything passes to three "stereo pair" amplifiers... Subwoofer,  Main space, and Small Rear   
Space, of which there is an equalizer on the Small Rear Space... Main space audio if the bathroom is included, is divided by careful wiring into three stereo "pairs".  All speaker pairs are wired so facing any pair one has left audio on the left, etc.  Even if facing the wall between pairs one is still hearing
"left from the left" except when in the kitchen facing at right angles to the speaker pair there, then
it reverses due to the location of the left-outlet on one side of the fireplace chimney firing into the wall...  I guess I will have to draw something up...

Eric
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David Pinnegar

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Re: Speakers for dry organ installations
« Reply #11 on: October 08, 2010, 09:04:52 PM »
Quote
The most natural sounding speakers will be ones where designers have made special efforts to minimise transducer movement

This leads on to the matter of multi-driver systems and crossovers. 

There have been single-cone loudspeakers that professed to cover the full range of hearing, but usually this was actually a rather truncated range; there are speakers with multiple cones attached to one voice-coil - which in effect use a mechanical crossover, which can only be less well defined than an electrical one.  In general, multiple drivers are used to cover the full range satisfactorily.  There are various problems that arise as a result; good design can minimise these for hi-fi and monitoring use both of which require good on-axis performance more than anything else.  However, when considering the off-axis performance, problems appear.  For any driver on a baffle of a certain size, the output will become more directional as the frequency gets higher; there may also be a substantial change in directivity at the point of crossing over.  Also, below a certain frequency the output drops because of an effect known as the baffle step (this can be corrected in the crossover, of course).  All this is already making our aim of an omnidirectional speaker a bit of a nonsense - but there's more!  If the drivers are not perfectly coincidental (as in Tannoy dual-concentric drivers, for instance), there will be comb filtering effects as we move off the axis of the speaker.  Actually, we're quite lucky that our hearing is tolerant enough to let us get away with all this at all.

Dear Paul

Your post is a superb analysis of the whole issue, and the paragraph above greatly interesting. It's for all these reasons why there is no "one" solution nor any one company that can offer everything as hi-fi to all and that for some purposes some things might be better and for others others . . .

Quote
We should not be using defects in the speaker to add their own character to the sound; this character should be in the original sample (or simulation if the sound is being modelled).

:-) I think that this is probably the only area where we might differ, and to do so of course is as you say nit-picking, and is probably the difference between the doctrinal backgrounds of physicists and engineers :-)

My rather pragmatic approach is that, bearing in mind no speaker can do everything, the cororally is that each speaker can do something! Indeed because some speakers can do some things better than other speakers, I like working with the advantages of stuff (as my sons would say) rather than bashing my head against brick walls in fighting against it or trying to achieve a perfection that's impossible to achieve.

When one is trying to achieve perfection however, one has to look at the closest and minutest detail. Therefore, to take Tony's distinction between producing and REproducing, when one is reproducing one is taking a recording from a microphone a little distance away from a pipe or pipes or instrument. When one is producing, one should be taking a recording from the physical interface of the pipe it its mouth and its end, as the sound source, for the final loudspeaker in the chain to reproduce _as_that_sound_ and produce that sound that emanated from the pipe itself at the point at which the air from the pipe became a sound.

Our problem is that taking the recording from the interface between the pipe and the volume of surrounding air is not possible.

So one might try to synthesise it as if the microphone was in the right place. At the interface, certain characteristics will be enhanced which will be diluted as the pipe air mixes with the static volume of the air outside and in the course of distance is lost. So there are possible defects in speaker drivers and enclosures which one can exploit to simulate the unrecordable as if it was and to pretend to be the pipe itself rather than being a reflection of the pipe in the mirror that is the microphone at a distance. So one might to try to drive the air in an analogous way.

In the old days of analogue simulation of organs, two methods were used - one to add harmonics together, demonstrated by the 1790 Grinda pipe organ video http://www.youtube.com/watch?v=_qqWNNlwV2U at 0:55 and the Cornet video on Hammerwood organ and Hammond http://www.youtube.com/watch?v=45OeT8E37FM and the other as on the Vickery organ http://www.youtube.com/watch?v=psnwJvDwBjE and the Ralph Jones Mini Metro Movable organ http://www.youtube.com/watch?v=yOAQ0DlhXKM  http://www.youtube.com/watch?v=vph8tZ1uOZ4 by putting square waves together to step synthesise sine, square and sawtooth waves, putting them through filters to accord with the "formants" of the pipe sounds required to synthesise the pipe stops. If one puts a good pipe signal recorded by the distant microphone as its mirror, whilst salt or monosodium glutamate might make a mushroom soup taste more like mushrooms, addition of a few ceps will do it like the real thing . . .

So the theory (and I don't expect you to agree with me or want to agree with me :) ) is that using a speaker of which the formants of its defects accords with the formants of the original pipe makes the distance recorded pipe sound like the pipe itself, analogous to bringing the microphone right up to the moving air interface so that the reflection we experience in the mirror which is the microphone appears whisper close to the source. It's as if putting a magnifying glass on the characteristics of the sound.

Sorry - this is a very difficult concept to explain.

The idea is not new - Conn did it with their "pipes" speakers, and I'm aware of other EOCS members who have been doing similar experiments.

Best wishes

David P
« Last Edit: October 09, 2010, 02:11:05 AM by David Pinnegar »

dragonser

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Re: Speaker considerations
« Reply #12 on: October 09, 2010, 12:45:04 AM »
Hi,
sorry if it is an obvious question but why shouldn't the defects in the speakers be used to add their own character to the sound ?
I can see that if the characteristics are not consistent or the speakers are being over driven so they might fail then I can understand why not.
I think that any speaker system will have some effect on the sounds produced and some speaker systems may respond in a way ( even if it is unintended ) that suits some Organs sounds.
on another subject, I always thought that the rear channels on a  surround sound  system had less information than the main front channels ? so if this is so then I think it makes sense that you wouldn't need speakers as large or as good quality as the front channels.
on the subject of speakers Yamaha did use a special speaker on a couple of their 1970's ? Organs that was shaped in the outline of a human ear ! I think they mentioned that it gave a natural sound ! ( I can't confirm if it did or not )

regards Peter B

P.S if it is relevant I feel I am more of an Engineer that a Physicist ! but probably not enough of either .........



We should not be using defects in the speaker to add their own character to the sound; this character should be in the original sample (or simulation if the sound is being modelled).

   

Paul

pwhodges

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Re: Speakers for dry organ installations
« Reply #13 on: October 18, 2010, 04:52:20 AM »
That Yamaha speaker (I recall it being shaped like a grand piano soundboard) had a very short life, and understandably dreadful reviews.  There is a clear distinction between reproducing a recording of a sound, and creating a sound through modelling or suchlike.

I know little about the Conn speakers - but the ones I know of were taken out of use after the effect of using them for reproducing a Hauptwerk organ was heard.

Paul
« Last Edit: October 18, 2010, 04:54:17 AM by pwhodges »

Doug S

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Re: Speakers for dry organ installations
« Reply #14 on: October 18, 2010, 05:30:02 AM »
From my somewhat limited experience combining digitally reproduced dry stops with actual pipework, it seems both benefit from the ability to be placed within a case and speak from an elevated position relative to the listener even, and perhaps especially, in a small space. With loudspeakers the case is the same with one addition. I've found much more pleasing results are had if the speakers are NOT pointed toward the listening space unrestricted. All of my speakers are placed within the casework adjacent to the pipework and directed upward. My reasoning is that with few exceptions the actual pipes speak in close proximity with many reflective surfaces and, except for front pipes in the casework, rarely to the listener unobstructed.
Conversely, whenever I've placed the speakers aimed directly at the listener (me), the sound is synthetic noticeably inferior to those placed interactively with the immediate environment. As yet however, I still find the digital  8' Open Diapason suffers greatly. It just doesn't deem to replicate the warm fullness of pipes, especially in the lower registers.

David Pinnegar

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Re: Speakers for dry organ installations
« Reply #15 on: October 18, 2010, 06:49:35 AM »
Hi!

Conn speakers - I haven't experienced them directly but imagine that they might absorb higher harmonics, so may well be OK for sythesized flute . . .? Certainly diapasons are critical . . . and for general Hauptwerk use one can imagine that they might be too specialised for a generality of stops . . .

I have been looking this evening at Tannoy theory. Interestingly at the 1kHz x-over frequency, the woofer and tweeter are connected out of phase, and at 1kHz this corrects the time lag from the tweeter to the woofer. Olson apparently contradicted the received opinion that the ear was phase independant and asserted that the phase of harmonics mattered. So if you've got a treble C at around 500 Hz, the second harmonic will be right in the crossover between the two, and may survive OK but the 3rd and 4th Harmonics will be out of phase. Doug - you might have seen my experiment showing the criticality of this part of the spectrum to diapasons - http://www.youtube.com/watch?v=vii521NGSos

It's intriguing that the Diapason as prime organ stop seems to have something elusively special about it to make electronic reproduction a little bit critical . . . Pipe organ builders need not worry!

(Whilst writing, Paul - thanks so much for your contribution and measurement on the reverb phenonomen - it's a real curiosity isn't it!?)

Best wishes

David P


revtonynewnham

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Re: Speakers for dry organ installations
« Reply #16 on: October 18, 2010, 02:54:23 PM »
Hi

The Conn "pipe" speakers, along with Allen's gyroscopic system, Compton's "Rotofons" and even Leslie speakers were all designed to introduce a bit of life to the analogue electronic organs of the day - and don't forget that single speaker installations were the norm at that time.  I don't know about the Conn's as I can't recall ever hearing a set live, only on recordings.  The other moving speakers worked tolerably well by the standards of the time - but they were not being fed with the sounds of sampled pipes (although it might be an interesting exercise to try a dry sample set through a pair of Rotophons in a large room.

To my ears, the biggest problem is that, whilst OK in adding a sense of space and life to full organ sounds, they don't really work with single notes.  Of course, the Leslie on high speed has become an effect in its own right, especially for Hammond organs (and other instruments in the light music/pop arena).

Every Blessing

Tony

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Re: Speakers for dry organ installations
« Reply #17 on: December 05, 2010, 01:04:47 PM »
Quote
Not only there are circumstances where people think that multiple speakers are _necessary_ - there being a distinction between necessity and desire, but often people think that speakers have to cost a lot of money.

http://seattle.craigslist.org/see/zip/2095553816.html

The above link explains why "good" speakers don't really have to cost a pile of money... Note the "price" ;) ;D 8) 8) 8) :o

If one really pays attention to the world around them... made ever so much more possible by the aid of devices such as this forum and the technology which supports it.........

The link above was emailed to me by a friend that knows I have an interest in such things...

Eric
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The objective is to reach human immortality—that is, to create things which are necessary to mankind, necessary to the purpose of the existence of mankind, and which have become the fruit that drives the creation of a higher state of mankind than ever existed before."

David Pinnegar

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Re: Speakers for dry organ installations
« Reply #18 on: December 06, 2010, 03:49:28 AM »
Dear Eric

Those beasts look just the job for an excellent pair of boxes for organ music . . . If only shipping across the pond wasn't so expensive. . . .

In seeing this post, I was expecting to see pictures of your distinctly interesting speakers for wet organ installations  ;D ;) !!!

Best wishes

David P

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Re: Speakers for dry organ installations
« Reply #19 on: December 06, 2010, 05:36:38 AM »
 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D

I have yet to figger out how to get the local machine to barf the data onto the forum :o >:(

Somewhere I am "missing" something.............

However... You are more than welcome to do the honors...

As far as a "wet" installation, I did cover the electronics to prevent a soaking if the rain kicked up ;)
but for the duration of the "concert" the weather did manage to cooperate. Before and after, however, the usual fall drizzle prevailed, so I removed the electronic bits and the smallish subwoofer to a drier environment, the large bass horn being nearly the size and weight of a refrigerator was merely moved to a location which would not impede the movement of motor vehicles in the drive, and the speaker removed to protect it also.

(Old combat wisdom-- If it's stupid but works, it isn't stupid ;D

Eric
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« Last Edit: December 06, 2010, 05:40:51 AM by KB7DQH »
The objective is to reach human immortality—that is, to create things which are necessary to mankind, necessary to the purpose of the existence of mankind, and which have become the fruit that drives the creation of a higher state of mankind than ever existed before."

 


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