Dear Sirs,
please excuse my maybe silly question.
I have a pair of Dynaudio speakers, 3 ways with these woofers (one per speaker):
http://www.gattiweb.com/images/dynaudio/24w75.pdf
I have great difficulties to find an amp that can drive properly these speakers in the bass region.
The bass response is always weak and out of control.
I am asking to any expert if from the specifications (Qts?) one can understand why and on the other hand which would be a very easy to drive woofer for example.
I mean, is it possible to understand from specs if the driver is easy to drive foe an amp or not ?
I am very interested to hear advice.
Thank you so much.
Kind regards,
beppe
please excuse my maybe silly question.
I have a pair of Dynaudio speakers, 3 ways with these woofers (one per speaker):
http://www.gattiweb.com/images/dynaudio/24w75.pdf
I have great difficulties to find an amp that can drive properly these speakers in the bass region.
The bass response is always weak and out of control.
I am asking to any expert if from the specifications (Qts?) one can understand why and on the other hand which would be a very easy to drive woofer for example.
I mean, is it possible to understand from specs if the driver is easy to drive foe an amp or not ?
I am very interested to hear advice.
Thank you so much.
Kind regards,
beppe
The 'control' will be dependent on a whole load of interacting factors such as the box, tuning, crossover and driver itself. Inherent damping, group delay and inductance will play a big part in the sound in the bass region.
beppe61 said:
It has a very weak magnet (very high Qes) in combination with a soft cone. Not the ideal parametres for good bass definition. 😉
Re: Re: Why is this woofer so difficult to drive properly.
Dear Sir,
thank you so much for your extremely kind and very valuable reply.
Let me please ask you something more (I am very ignorant but eager to learn).
1) So low Qes means a powerful magnet, right?
Very interesting.
2) which data shows the softness of the cone?
The Qts maybe? and if so high Qts means soft cone?
3) Could you give me some example of very good drivers for the bass frequency range?
As I said I heard my speakers sounding good only when driven by very high-current power amps, able to give high peak current.
And this is unfortunate beacuse this kind of amps usually do not come cheap.
Thank you greatly again for your very valuable advice.
Kind regards,
beppe
P.S. I looked at your site. Truly impressive indeed.
My sincere congratulations !
Dear Sir,
thank you so much for your extremely kind and very valuable reply.
Let me please ask you something more (I am very ignorant but eager to learn).
1) So low Qes means a powerful magnet, right?
Very interesting.
2) which data shows the softness of the cone?
The Qts maybe? and if so high Qts means soft cone?
3) Could you give me some example of very good drivers for the bass frequency range?
As I said I heard my speakers sounding good only when driven by very high-current power amps, able to give high peak current.
And this is unfortunate beacuse this kind of amps usually do not come cheap.
Thank you greatly again for your very valuable advice.
Kind regards,
beppe
P.S. I looked at your site. Truly impressive indeed.
My sincere congratulations !
Hi,
are you considering fitting alternative bass drivers ?
In that case we would need the specs of the boxes.
The Scanspeak driver is more suited to a 2-way than a 3-way.
Qts is formed from Qes and Qms.
Qms is usually high, so Qts is near but lower than Qes.
Low Qts (therefore low Qes) does indicate a powerful magnet system.
The "softness" of the cone is related to its material, metal cones are hard.
However the idea you must have hard cones for good bass definition
is simplifying matters too far, there are a myriad of infuences.
The Scanpspeak driver would be good on an open baffle with
something like the FR125S, possibly with a supertweeter.
You'd need a sub for the bass end.
🙂/sreten.
are you considering fitting alternative bass drivers ?
In that case we would need the specs of the boxes.
The Scanspeak driver is more suited to a 2-way than a 3-way.
Qts is formed from Qes and Qms.
Qms is usually high, so Qts is near but lower than Qes.
Low Qts (therefore low Qes) does indicate a powerful magnet system.
The "softness" of the cone is related to its material, metal cones are hard.
However the idea you must have hard cones for good bass definition
is simplifying matters too far, there are a myriad of infuences.
The Scanpspeak driver would be good on an open baffle with
something like the FR125S, possibly with a supertweeter.
You'd need a sub for the bass end.
🙂/sreten.
sreten said:
Dear Mr. Sreten,
thank you sincerely for your kind and valuable reply.
1) Actually l was looking for a confirmation, from the reading of the specifications, that this woofer is not the easiest load for an amp, having tried more than one without satisfaction.
Now I understand that the magnet is too small for such a driver.
To answer to your question, I have not decided.
I am trying to evaluate if it would be better to look for a more powerful amp that could drive adequately the driver or change completely the loudspeker for something easier to drive.
What do you suggest?
2) Thank you very much for your extremely valuable explanation.
So the Qts is a very fundamental parameter.
3) Perfectly clear. No question.
4) Are you talking of the 24W75 ? it is a Dynaudio driver actually.
Could you elaborate your suggestion?
What would be your choice? rebuilding the speaker, maybe with different driver, or choosing another power amp ? and if so which kind of power amp?
Thank you so much again.
Kind regards,
beppe
I would certainly agree with the above comments. Another indication of a weak magnet is the Bl for 4.3. For a woofer I'd expect roughly twice that. I didn't see enclosure size and tuning (if ported) figures, they will have an effect on your problem.
Woofers I have had very good luck with are the Scanspeak 25W/8565-01. (But watch out for that 2.5kHz peak, it needs a trap to suppress it adequately.) The specs are representative of a woofer that is easy to design with, and easily driven. The lower the Qt the more "damped" the speaker is, to simplify a bit. 0.30 to 0.34 works out well for me, and is usable in both sealed and ported enclosures. (I prefer ported, with the box tuned to a bit less than 20 Hz for full range bass. )
I plugged the Dynaudio numbers into the LEAP quick design utility, and the best sealed design was 110 liters; the vented box was 257 liters, tuned to 20 Hz. All designs showed peaks; in these two cases the peaks were 2-3 dB in the 40-50 Hz region. Other versions had higher peaks, and I would guess that that is your real problem.
So my 2 cent suggestions: try a trial box or two, sealed and ported, to see if the drivers can be rescued. Just a quick, but non-leaky, box to try out the sizes. If that is unsatisfactory, then I would suggest new drivers as less expensive than a new amplifier, and you'd be correcting the problem at the source.
Woofers I have had very good luck with are the Scanspeak 25W/8565-01. (But watch out for that 2.5kHz peak, it needs a trap to suppress it adequately.) The specs are representative of a woofer that is easy to design with, and easily driven. The lower the Qt the more "damped" the speaker is, to simplify a bit. 0.30 to 0.34 works out well for me, and is usable in both sealed and ported enclosures. (I prefer ported, with the box tuned to a bit less than 20 Hz for full range bass. )
I plugged the Dynaudio numbers into the LEAP quick design utility, and the best sealed design was 110 liters; the vented box was 257 liters, tuned to 20 Hz. All designs showed peaks; in these two cases the peaks were 2-3 dB in the 40-50 Hz region. Other versions had higher peaks, and I would guess that that is your real problem.
So my 2 cent suggestions: try a trial box or two, sealed and ported, to see if the drivers can be rescued. Just a quick, but non-leaky, box to try out the sizes. If that is unsatisfactory, then I would suggest new drivers as less expensive than a new amplifier, and you'd be correcting the problem at the source.
Hi,
I'd consider changing the bass unit in the speakers,unless as a
whole they can be sold for a good price and fitting a new driver
would ruin their value.
🙂/sreten.
I'd consider changing the bass unit in the speakers,unless as a
whole they can be sold for a good price and fitting a new driver
would ruin their value.
🙂/sreten.
Curmudgeon said:
Dear Mr. Curmudgeon,
thank you so much again for your kind and valuable reply.
I wonder from where all the Dynaudio fame comes if their drivers are so poorly performing.
On the basis of your words I understand that Scanspeak drivers are so much better.
When you say " The lower the Qt the more "damped" the speaker is, to simplify a bit. 0.30 to 0.34 works out well for me " are you referring to Qts ?
I think that I will go on replacing these speakers.
Are so unfriendly to use that make me nervous.
Thank you very much indeed.
Kind regards,
beppe
sreten said:
Dear Mr. Sreten,
on the basis of all the valuable advices I am getting here, I think that the value of this kind of speaker is not so high.
Actually I have two pair of Dynaudio with these drivers:
one 3 ways pair
24W75 + D52 + D21
one 2 ways pair
23W75 + D28
After all I could try to sell the domes and burn the remains.
Thank you very much indeed.
Kind regards,
beppe
Absolutely, change the woofer man. Amplification always costs more when trying to fix speaker-related problems with electronics.
Fix the speaker problem and it will cost less time and money.
Fix the speaker problem and it will cost less time and money.
beppe61 said:
What is the inside volume of the boxes you are using? Are they closed, or vented or have variovents (a hole plugged with fiberglass)? If they are vented what is the diameter and length of the vent? How much and what kind of damping material is in the boxes? What kind of xover are you using? Whose design are they?
If you provide these, you are likely to get better advice.
Bose(o) said:
Dear Mr. Bose,
thank you for your kind and helpful reply.
Nevertheless this choice sounds like a defeat to me.
I would have liked very much the idea of taming these woofers and put them under control.
Thank you very much and kind regards,
beppe
Hi Beppe-
Yes, I was referring to Qts, which is actually Qes*Qms/Qes+Qms.
I've not followed Dynaudio drivers since they became unavailable to the DIY market. However, it looks as if this driver is designed for a specific application, and is unusual. Perhaps the shallow depth, and the applications "mobile hifi" and "TV monitors" are the main design factors. In any event, it is not typical of the Dynaudio drivers I remember, and reviews I read of their complete systems don't indicate this sort of problem. In any event, comparisons need to be made on the basis of individual models, not just the brand name. And I mentioned SS because it has worked out well for me in some projects, and the specs are "middle of the road" for good woofers, but by all means many other companies make very good woofers.
They may be salable; some people might like the bass quantity, even though it lacks tightness and control... And I suspect that that was the intended market for this model.
But don't give up yet, answering the list of questions that Feyz asked might lead to some ready improvements that would help for now. One possibility might be that drivers might be found that would work well in your existing cabinets, so burning would be a bit hasty. 🙂 I'm sorry your first project (I think it is?) has a problem, but do not despair. We've all been there. About 25 years ago, I built sub woofers to go with my Magnepans, based on a new Audax model I'd read about. I took shop class, and built cabinets with 4 drivers each, with double 1" MDF walls for 2". The Audax units that had been the basis for the article I read were prototypes, and the Thiele-Small parameters for the production units were completely different. (This was the old Audax, before the collapse and resurrection. ) The response was about -3dB at 60 Hz. I was able to rescue it with a passive crossover/equalizer and biamping, and it finally turned out quite well, but it certainly provided a "learning opportunity".
Yes, I was referring to Qts, which is actually Qes*Qms/Qes+Qms.
I've not followed Dynaudio drivers since they became unavailable to the DIY market. However, it looks as if this driver is designed for a specific application, and is unusual. Perhaps the shallow depth, and the applications "mobile hifi" and "TV monitors" are the main design factors. In any event, it is not typical of the Dynaudio drivers I remember, and reviews I read of their complete systems don't indicate this sort of problem. In any event, comparisons need to be made on the basis of individual models, not just the brand name. And I mentioned SS because it has worked out well for me in some projects, and the specs are "middle of the road" for good woofers, but by all means many other companies make very good woofers.
They may be salable; some people might like the bass quantity, even though it lacks tightness and control... And I suspect that that was the intended market for this model.
But don't give up yet, answering the list of questions that Feyz asked might lead to some ready improvements that would help for now. One possibility might be that drivers might be found that would work well in your existing cabinets, so burning would be a bit hasty. 🙂 I'm sorry your first project (I think it is?) has a problem, but do not despair. We've all been there. About 25 years ago, I built sub woofers to go with my Magnepans, based on a new Audax model I'd read about. I took shop class, and built cabinets with 4 drivers each, with double 1" MDF walls for 2". The Audax units that had been the basis for the article I read were prototypes, and the Thiele-Small parameters for the production units were completely different. (This was the old Audax, before the collapse and resurrection. ) The response was about -3dB at 60 Hz. I was able to rescue it with a passive crossover/equalizer and biamping, and it finally turned out quite well, but it certainly provided a "learning opportunity".
I own some dynaudio speakers and they've always had tight controlled bass with adcom, hafler, and diy krell amps. 4 X 24w75 in sealed enclosures.
Lee1234 said:
Dear Mr. Lee1234,
thank you very much for your kind and valuable reply.
May I ask you which models are you reffering at?
I have a Adcom GFA 545 that fails to give an adequate bass response, even if the sound is pretty good.
But a real and solid bass is lacking, unfortunately.
I have been told that the reason is the poor single toroidal and have been suggested to replace it with two 500VA stacked for a nice improvement.
The mod will cost me about 150 euro and should be pretty easy to do.
I would like to know which is the minimum price of admission to good bass.
Thank you very much indeed.
Kind regards,
beppe
I have a NAD C320BEE with a single torroidal power supply, the bass is tight and controlled and, the sound is very musical. Adding more current does increase control over the cone's motion and that was clearly evident when I upgraded from an old Technics to my current NAD amp.
Hi,
anyone interested in building open baffles would
be very interested in those dynaudio bass drivers.
Replacing the bass unit in the 3-way should be straightforward,
in the 2-way it would be more difficult because of the crossover.
🙂/sreten.
anyone interested in building open baffles would
be very interested in those dynaudio bass drivers.
Replacing the bass unit in the 3-way should be straightforward,
in the 2-way it would be more difficult because of the crossover.
🙂/sreten.
Feyz said:
Dear Sir,
The internal dimension (net) are
24*25*45 cm for the 2 ways
27*25*55 cm for the 3 ways
both have a variovent (10cm diameter) on the upper part in the back
They are pretty full of dumping material similar to glass wool.
I could not examine teh x-over beacuse is bolted in the back.
I will try again.
Nevertheless the aim of my original question was to know if it is possible from the specifications of the woofer to understand if it is easy to drive also with a not particularly powerful amp.
Or otherwise, could you suggest a 8" woofer that is very easy to drive?
What value I have to look at to understand that a woofer is an easy load even for a weak amp ?
Of weak amp is full the world and this could save me a lot of money.
Thank you very much indeed.
Kind regards,
beppe
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