At that time, Dynaudio was still SEN-Labs. I still have a pair of their old paper 21cm woofers (ancestor of the 21W54), 12 ohm nominal impedance, just looking for the right project. I'll see if I can find one of Precedent's old brochures for the MZ Mod II/III speakers, scan it, and send it along.
I made more experiments with the ZDL tweeter and Elias is right. Simply hanging the tweeter in "free air" is not the solution. Some damping of reflexions is necessarry for best results and i arived at a good result by damping the back of the tweeter with foam and damping the bucket with poly stuff. That ain´t look pretty but this is just a first attempt.
See the response i get now compared with the measurement without damping.
See the response i get now compared with the measurement without damping.
Attachments
First you see that under 2kHz the ZDL tweeter does better the SEAS in third. This is what i found with a lot of tweeters that use Ferrofluid. In the SEAS some compression is going on but it is still well controlled. Now i made some Multitone measurements. Here the diffences come out more clear i think. The ZDL tweeer has more low level hash and should not be used much under 2kHz but the SEAS ( red ) has more high level intermodulation.
What sounds better can only be found out with listening tests. I can not use the SEAS anyway because it has a wide baffle and it does not fit into this particular design.
What sounds better can only be found out with listening tests. I can not use the SEAS anyway because it has a wide baffle and it does not fit into this particular design.
Ah, I was not aware of that version of the Vifa 3/4" tweeter with the rear chamber! We had tested the previous (no-chamber) version for similar use, but went with another tweeter for that particular application. The one with the chamber looks much more promising. 
I will certainly be ordering some of the chambered version for my own use.
It's funny, I had just bought some MDM-55 midranges a few months back to test something like the Stoll speaker (the omni woofer being something we have been doing consistantly for more than 30 years already at Ohm, of course). I had not known of Stoll until reading your thread here. In some ways it is quite similar to some Ohm speakers, but, thankfully missing some key design features [which I'd not want to disclose publicly].
I will certainly be ordering some of the chambered version for my own use.It's funny, I had just bought some MDM-55 midranges a few months back to test something like the Stoll speaker (the omni woofer being something we have been doing consistantly for more than 30 years already at Ohm, of course). I had not known of Stoll until reading your thread here. In some ways it is quite similar to some Ohm speakers, but, thankfully missing some key design features [which I'd not want to disclose publicly].
I had a long discussion with Dominik and this is what he would like to clarify:
There are two way to show sensitivity : at 1W/ 1m and at 2.83V/ 1m. An 8 Ohm speaker whith a sensitivity of 90dB @ 1W/ 1m whould also have a sensitivity of 90dB @ 2.83V/ 1m. The tweeter i am using is a 4 Ohm ( DIN ) design with a DC value of 3.3 Ohm and has a sensitivity of ca. 90dB @ 2.83V/ 1m. Measured as 1W/ 1m the sensitivity whould be 3dB lower so 87dB @ 1W / 1m.
I am using the 2.83V / 1m method.
Second he found it absolutely correct that the sound travels around the driver. He was encuraging me to remeasure the ZDL tweeter against the SEAS on a string hanging from the ceilling . The ZDL tweeter under this conditions should have a very flat response acording to his experience.
Third a ZDL speaker should have no early reflexion the first 17msec that are stronger then -35dB.
Forth, the Q2-b is designed to be listened too very close ( not more then 1m, or as long as your arm stretched out ) in a well damped room so his setup is even more stringent then mine.
Fifth he agrees with Linkwitz that the sound a speaker produces to the sides and even to the back is extremely important for "timbre" especially in the fundamental tone area under 1kHz and that this is not researched well or got too little attention.
I start to feel the burden.
Critofur, i had an Ohm F back then and besides grilling amps ( the big Dynaco worked ) the sound we got was quite psychedelic. I had forgotten that i already had a lot of experience with Omnis 35 years back. Well, the ZDL will not excactly be an omni but i will try to extend the off axis treble as much as i can.
There are two way to show sensitivity : at 1W/ 1m and at 2.83V/ 1m. An 8 Ohm speaker whith a sensitivity of 90dB @ 1W/ 1m whould also have a sensitivity of 90dB @ 2.83V/ 1m. The tweeter i am using is a 4 Ohm ( DIN ) design with a DC value of 3.3 Ohm and has a sensitivity of ca. 90dB @ 2.83V/ 1m. Measured as 1W/ 1m the sensitivity whould be 3dB lower so 87dB @ 1W / 1m.
I am using the 2.83V / 1m method.
Second he found it absolutely correct that the sound travels around the driver. He was encuraging me to remeasure the ZDL tweeter against the SEAS on a string hanging from the ceilling . The ZDL tweeter under this conditions should have a very flat response acording to his experience.
Third a ZDL speaker should have no early reflexion the first 17msec that are stronger then -35dB.
Forth, the Q2-b is designed to be listened too very close ( not more then 1m, or as long as your arm stretched out ) in a well damped room so his setup is even more stringent then mine.
Fifth he agrees with Linkwitz that the sound a speaker produces to the sides and even to the back is extremely important for "timbre" especially in the fundamental tone area under 1kHz and that this is not researched well or got too little attention.
I start to feel the burden.
Critofur, i had an Ohm F back then and besides grilling amps ( the big Dynaco worked ) the sound we got was quite psychedelic. I had forgotten that i already had a lot of experience with Omnis 35 years back. Well, the ZDL will not excactly be an omni but i will try to extend the off axis treble as much as i can.
Hello,
Yes the around diffraction is reality. Wavelets have teached me quite a lot about audio. It's very good visualisation tool.
The tweeter I used with that wavelet graph was Peerless dome with 100mm round front plate.
But I think sphere is a compromise, it tries to minimise front diffraction but it maximises around diffraction. Better to put the element in the end of a long tube so bacwards diffracted sound cannot turn back again.
This comes to mind:
That is not going to happen unless the room size is at least 6*6*6m and you're listening at 3m distance from boundaries, also the floor Not very domestic situation.
I think it is better to use very high directivity speakers (e.g. dipole line arrays) in the midrange to avoid the room.
- Elias
Yes the around diffraction is reality. Wavelets have teached me quite a lot about audio. It's very good visualisation tool.
The tweeter I used with that wavelet graph was Peerless dome with 100mm round front plate.
But I think sphere is a compromise, it tries to minimise front diffraction but it maximises around diffraction. Better to put the element in the end of a long tube so bacwards diffracted sound cannot turn back again.
This comes to mind:
An externally hosted image should be here but it was not working when we last tested it.
That is not going to happen unless the room size is at least 6*6*6m and you're listening at 3m distance from boundaries, also the floor
Not very domestic situation.I think it is better to use very high directivity speakers (e.g. dipole line arrays) in the midrange to avoid the room.
- Elias
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Thanks Elias for this contribution. Dominik was in contact with the designer of the Naultilus at that time i think.
I agree that this 17msec "time gap" is hard to reach. Nevertheless i like the result much
that the Stoll speakers present.
I have already stated that the ZDL has no aspiration to be "the best" loudspeaker.
When you have not heard the Stoll speakers it is hard for me to describe how they sound.
I can only say that it is a pleasant experience so i will follow this road to the end.
What i will do with the "around diffraction" issue i can not say but i have started to experiment with damping in the back. This detail is not aproved by Dominik though. He prefers the minimalistic baffle option without damping in the back. In fact the tweeter he uses in his bigger monitor ( i try to find a picture ) has a bullet shaped extention that absorbes the backwave of the tweeter to a certain degree.
Thanks Elis also that you have reveiled the tweeter you measured.
I agree that this 17msec "time gap" is hard to reach. Nevertheless i like the result much
that the Stoll speakers present.
I have already stated that the ZDL has no aspiration to be "the best" loudspeaker.
When you have not heard the Stoll speakers it is hard for me to describe how they sound.
I can only say that it is a pleasant experience so i will follow this road to the end.
What i will do with the "around diffraction" issue i can not say but i have started to experiment with damping in the back. This detail is not aproved by Dominik though. He prefers the minimalistic baffle option without damping in the back. In fact the tweeter he uses in his bigger monitor ( i try to find a picture ) has a bullet shaped extention that absorbes the backwave of the tweeter to a certain degree.
Thanks Elis also that you have reveiled the tweeter you measured.
Sorry Elias,
your "around diffraction" could be reality, yes. But isn't it only an assumption as long as you have not proved it by experiment? Can we see the same kind of measurement, but now with some means to effectively prevent "the wave travelling around the backside of the tweeter"?
Rudolf
Hello Joachim,
Your ZDL effort will be interesting to follow. I searched near field in DIYaudio and found your thread.
In an effort to take the headphones off my head and move the phantom image from between my ears and create an illusion of the performance on stage in front of me I have set up a pair of speakers at 1.84 meters from my seat. The phantom image and sound stage are amazing. I followed your procedure of adjusting the toe in to maximize the phantom image with better than expected results.
Thanks for your posts.
DT
All just for fun!
I posted a wrong information.The bigger Monitor i have talked about here is not a Stoll product.
Second, sreten, the information you posted here is not very helpfull, it feels even depressing. You have not even measured the tweeter yourself and post the opinion of another person. The designer must have had good reasons to use it and it can behave totally different under conditions that are not similiar to the Zaph measurements.
Please do not put up more junk like this on this thread. It may even harm the reputation of the designer and without that you heard or measured that speaker ever.
On a more general issue i will not do any more comentary on the Stoll monitor and the bigger monitor. The only experience i have with those products is listening to them under familiar conditions and i liked what i heard. That experience insired me to do something similiar here. I have no idea about the working of both products so please let us discuss my work here. As i said, what i am doing here is not a straight copy. What i wanted to comunicate is, that the ZDL conzept is not my original idea.
Second, sreten, the information you posted here is not very helpfull, it feels even depressing. You have not even measured the tweeter yourself and post the opinion of another person. The designer must have had good reasons to use it and it can behave totally different under conditions that are not similiar to the Zaph measurements.
Please do not put up more junk like this on this thread. It may even harm the reputation of the designer and without that you heard or measured that speaker ever.
On a more general issue i will not do any more comentary on the Stoll monitor and the bigger monitor. The only experience i have with those products is listening to them under familiar conditions and i liked what i heard. That experience insired me to do something similiar here. I have no idea about the working of both products so please let us discuss my work here. As i said, what i am doing here is not a straight copy. What i wanted to comunicate is, that the ZDL conzept is not my original idea.
I have now permission from Martina Schoener ( Garrard, Loricraft ) to tell you what the big midfield monitor is. It is a L`Art du Son No.5 and Martina had input concerning the tonal balance. There is also provission to tune the bass to the room.
That speaker was played on the Klangbilder 2009 in Vienna.
The tweeter is not the Swans although it looks similiar to me. My mistake.
That speaker was played on the Klangbilder 2009 in Vienna.
The tweeter is not the Swans although it looks similiar to me. My mistake.
Hi,
This is a classic example of shooting the messenger, if you don't like
what I posted its not my fault, its the best information I have available,
and if you want to denigrate my motives that is your problem not mine.
There is nothing depressing about real information. How you use that
information (available on Zaphs site, I would not have quoted Zaph
if the back up information was not there) depends on your usage.
If you want to call it "Junk" then what is this thread about ?
rgds, sreten.
Hi Sreten !
I did several mistakes here. First i said the bigger monitor is a Stoll product. It is not.
It is a L´Art du Son product. Then i said it is a Swans tweeter, it is not.
I apologise for that and i hope that you accept my apology.
I also regret the use of quite strong language. I simply felt cornered and that feeling was not pleasant. It was a spontaneous reaction.
What i stand too is that i only trust my own measurements. I simply do not know how the Zaph measurements have being done in detail.
I did several mistakes here. First i said the bigger monitor is a Stoll product. It is not.
It is a L´Art du Son product. Then i said it is a Swans tweeter, it is not.
I apologise for that and i hope that you accept my apology.
I also regret the use of quite strong language. I simply felt cornered and that feeling was not pleasant. It was a spontaneous reaction.
What i stand too is that i only trust my own measurements. I simply do not know how the Zaph measurements have being done in detail.
Hi,
Zaph's measurements are as good as it gets for internet information,
and far more reliable* than manufacturers published curves generally,
except for the cases he states the manufacturer has good specs.
A great source source for real CSD's, distortion, responses and parameters.
More than one person has noted stuff designed according to Zaphs
measurements sounds better than using their own measurements,
the obvious implication being some measurements are "better".
rgds, sreten.
Noting the caveat driver consistency can be a moving target.
*Certainly far more consistent for comparative analysis.
Zaphaudio.com , there are other test sites but its the best ....
Zaph's measurements are as good as it gets for internet information,
and far more reliable* than manufacturers published curves generally,
except for the cases he states the manufacturer has good specs.
A great source source for real CSD's, distortion, responses and parameters.
More than one person has noted stuff designed according to Zaphs
measurements sounds better than using their own measurements,
the obvious implication being some measurements are "better".
rgds, sreten.
Noting the caveat driver consistency can be a moving target.
*Certainly far more consistent for comparative analysis.
Zaphaudio.com , there are other test sites but its the best ....
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