Dominik Stoll recommends that you read the following :
file:///Users/joachimgerhard/Documents/Loudspeakers:%20Objective%20evaluations%20-%20Part%202:%20Measuring%20the%20essential%20properties%20of%20loudspeakers.webarchive
file:///Users/joachimgerhard/Documents/Loudspeakers:%20Objective%20evaluations%20-%20Part%202:%20Measuring%20the%20essential%20properties%20of%20loudspeakers.webarchive
OK, thanks. This is pretty much chapter 18 of Toole's book and one of the best chapters in that book at all. The web link has less info but good stuff anyway.
I have the book too. I think Dominik wanted to stress the importance that on AND off axis performance matters.
Hi Joachim,
While Floyd Toole has done much to advance the art in Speaker design, the positions he takes in the paper you quote are hardly considered universally agreed (one might almost say widely disagreed with, except for his insistence on a slow and even handed change of DI, even this is not universally agreed, as we see in many threads here).
Joachim, have you ever experimented with cardioid speakers?
The few experiments I did so far and the results MEG get with their RL901K where/are most remarkable. In the case of the MEG's shame about Herr Kieslers insistence on analogue crossovers full of TL082 (inlcuding analogue time alignment using allpass filters) and high feedback mosfet amp's for power. Even with those I rank the RL901K in my top ten of all time.
I am still wondering what a really optimised full range cardiodid without ton's of Op-Amp's and high feedback poweramp's will sound like. Maybe I find the time one day.
But that is enough threadjacking, afyer all you want to make something that is almost an omnipolar system, not unipolar...
Ciao T
While Floyd Toole has done much to advance the art in Speaker design, the positions he takes in the paper you quote are hardly considered universally agreed (one might almost say widely disagreed with, except for his insistence on a slow and even handed change of DI, even this is not universally agreed, as we see in many threads here).
Joachim, have you ever experimented with cardioid speakers?
The few experiments I did so far and the results MEG get with their RL901K where/are most remarkable. In the case of the MEG's shame about Herr Kieslers insistence on analogue crossovers full of TL082 (inlcuding analogue time alignment using allpass filters) and high feedback mosfet amp's for power. Even with those I rank the RL901K in my top ten of all time.
I am still wondering what a really optimised full range cardiodid without ton's of Op-Amp's and high feedback poweramp's will sound like. Maybe I find the time one day.
But that is enough threadjacking, afyer all you want to make something that is almost an omnipolar system, not unipolar...
Ciao T
I think Joachim is interested in recreating or even improving on a sensation he has experienced before, and regardless of methods. At least something different needs to be tried so that one can understand what else is important.
The only full range cardioid i ever heard is a JM Renaud model that was never put in production. I heard it many years ago under show conditions in Paris so i can not remember exactly how it sounded. It left a more lasting impression visually. Some time ago i visited Joseph Szall in Turin and he had a cardioid from Hungary that we did not play,
so sorry, i am not an expert on cardioids. Concerning MEG i could not care less. This is absolutely not the sound i am after. What i thought about is making the woofer of the ZDL a cardiode. That should have some advantage in room matching the bass. I could imagine an overzized bass reflex tunnel that begins shortly after the driver and extends to the back. This whould be a mix of a reflex and a cardioid.
I know Geddes work and i had the chance to talk to him in person. Again, i respect his work but have not listened to one of his creations.
Yes, soongsc, it is that special freedom and openness of the sound that the Stoll monitors do that inspires me. If i can improve on that i do not know.
Concerning further development work i have now a plastic ball where i can try the midrange in.
Markus, thanks for the link. This gets even more interesting then i thought.
so sorry, i am not an expert on cardioids. Concerning MEG i could not care less. This is absolutely not the sound i am after. What i thought about is making the woofer of the ZDL a cardiode. That should have some advantage in room matching the bass. I could imagine an overzized bass reflex tunnel that begins shortly after the driver and extends to the back. This whould be a mix of a reflex and a cardioid.
I know Geddes work and i had the chance to talk to him in person. Again, i respect his work but have not listened to one of his creations.
Yes, soongsc, it is that special freedom and openness of the sound that the Stoll monitors do that inspires me. If i can improve on that i do not know.
Concerning further development work i have now a plastic ball where i can try the midrange in.
Markus, thanks for the link. This gets even more interesting then i thought.
Based on my own experience as audiophile and designer, the following in the order of magnitude influences this:
1. CSD
2. Diffraction, self->baffle->enclosure. spread diffraction spectrum.
3. Dispersion
I am recently planning on doing some measurements related with how filtering/equalization will effect CSD. I know for a fact that driver CSD is imrpoved when somewhat equalized, but to what degree and how to further control it, I will be studying it further. Good to see people working in various aspects of sound reproduction improvement. Hope we break new ground.
1. CSD
2. Diffraction, self->baffle->enclosure. spread diffraction spectrum.
3. Dispersion
I am recently planning on doing some measurements related with how filtering/equalization will effect CSD. I know for a fact that driver CSD is imrpoved when somewhat equalized, but to what degree and how to further control it, I will be studying it further. Good to see people working in various aspects of sound reproduction improvement. Hope we break new ground.
I choose drivers with a very extended and flat response and i try to create a mechanical environment that does not do much harm to this. I will also use low order crossovers if posible. That way, stored energy will be reduced. To equalise drivers to reduce enegy storage is posible but then you need a digital equalizer. I will try to stay in the analog domain.
Joachim,
Have you heard the RL901K under decent set-up conditions (I feel the smaller units I heard have too many compromises)?
Otherwise I would suggest to do that anyway, for completeness. It is a rather different beat from a different drummer.
Despite the many philosophical issues I have with the build in electronics I found the results very impressive (not in the way of "sounding impressive" but in the context of getting out of the way), in direct comparison to ton's of other studio monitors...
That sounds a lot like how MEG do it for the bass. 🙂 They have essentially a de-tuned reflex combined with flow resistance. This is pretty similar to the way cardiodid operation was achieved in the old east german installed sound "Tonsaeulen" (sound columns), which within their arguably limited bandwidth showed excellently controlled DI. But the current implementation MEG uses seems to retain the cardiodid operation to much lower frequencies.
For the midrange they use the driver on an open baffle with a rear "muffler" (similar stuff was discussed here before) and the tweeter does not really need much help to be cardiodid.
My own experiments where all active using the combination of omnipole and dipole al low frequencies to achieve directivity control without the compromises entailed in using just a single driver.
For midrange I find that basotect and a short (ideally expanding) tunnel (similar to what MEG has been doing for the last two and a halve decades) very workable, though I am again intreagued by pursuing active solution, as it gives more control and indeed fully adjustable directivity (like the variable directivity microphones).
Ciao T
Have you heard the RL901K under decent set-up conditions (I feel the smaller units I heard have too many compromises)?
Otherwise I would suggest to do that anyway, for completeness. It is a rather different beat from a different drummer.
Despite the many philosophical issues I have with the build in electronics I found the results very impressive (not in the way of "sounding impressive" but in the context of getting out of the way), in direct comparison to ton's of other studio monitors...
That sounds a lot like how MEG do it for the bass. 🙂 They have essentially a de-tuned reflex combined with flow resistance. This is pretty similar to the way cardiodid operation was achieved in the old east german installed sound "Tonsaeulen" (sound columns), which within their arguably limited bandwidth showed excellently controlled DI. But the current implementation MEG uses seems to retain the cardiodid operation to much lower frequencies.
For the midrange they use the driver on an open baffle with a rear "muffler" (similar stuff was discussed here before) and the tweeter does not really need much help to be cardiodid.
My own experiments where all active using the combination of omnipole and dipole al low frequencies to achieve directivity control without the compromises entailed in using just a single driver.
For midrange I find that basotect and a short (ideally expanding) tunnel (similar to what MEG has been doing for the last two and a halve decades) very workable, though I am again intreagued by pursuing active solution, as it gives more control and indeed fully adjustable directivity (like the variable directivity microphones).
Ciao T
Mr Gerhard, please read my blog about directivity in the section 'above 300 Hz'(link in signature). It goes into the different types of patterns and their effects on what you hear when you get a chance. Dr. Toole's book may explain it better, but uses many more words and mine is written by an ignoramus.😱 I'd imagine there in Germany you'd have access to the Behringer 1030A and maybe even the 1031A(not available in the States) for a wide polar pattern. It's not an idealist's speaker(5" speaker tuned too high and limited output), but it's a bargain. It would be interesting to hear your comparison of it to this your current speaker of desire. One thing to think about when getting a feel for radiation pattern is your listening distance. We audiophiles(get used to the term people--you are one reading this) typically listen in the 'transition zone'. I think that sort of leaves are options fairly open but not idealized in any way.
Good luck on your quest,
Dan
Good luck on your quest,
Dan
With an MD9550 and a felt-back one could even think about a fullrange cardioid.
Lautsprecher Shop Intertechnik - Hochtöner :: Nova by Intertechnik :: Lautsprecher ::
Lautsprecher Shop Intertechnik - Hochtöner :: Nova by Intertechnik :: Lautsprecher ::
Joachim, can you remember what kind of music source was being played, what equipment?
Thorsten, no, i have not heard the MEGs in a familiar setup. Doc Feikert swears on them and when i visit the good doctor i give them a second chance. The cardiod bass and the ventilated midrange is not a bad idea i think and maybe i can learn something. Dantheman, thanks for the link. If i understand you right you seem to prefer wide dispersion speakers. I have heard the Pluto many times and in the nearfield they work well. I just whould go for some more treble resolution. el`OL, yes a fullrange cardioid is another option and i will experiment with ventilating and damping the back of the drivers but i do not like to go too far from Dominks original idea. Soongsc, at Essex we had an unbespoke ADC CD player where we used the digital SPDIF output. The rest of the electronics ( DSP, DA Converter, Power Amps ) and the speakers had been designed and build by Prof. Hawksford, Dr.Bews ( LFD ), Dr.Greenfield and me. Even the cable was our own construction. I think that this holistic aproach was the way to success. You really have to control the whole chain if you want a result like that.
I pulled together old measurements to do a quick EQ. There were some encouraging characteristics of the sound, I would also express it as "unspectacular and natural" in a way that did not sound real. Music was played from a computer, however, we had to run it through two sound cards in the same computer. I'm going to try and get some measurements. Everything except the computer hardware and software were our design, including interconnects. It is quite interesting though.
Is it not true that in a minimum phase system (and I realize not all speakers are minimum phase) an analog equalizer can "fix" energy storage-induced peaks in the speaker's response, at least at one point in space? If the peaks in the response are different at different listening positions, then this will not be a complete solution, but it is at least possible that an analog equalizer can fix energy storage problems. Or am I confused?
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