beppe61 said:
1) I don't have much experience with different amps, sorry.
3) Closing completely the variovent will cause the impedance of the driver to rise at resonance frequency. This means it will draw less current around the resonance frequencies. It will somewhat change the low frequency response also, but I don't think too much. So it is worth a try
5) Your signature shows you are in Italy, I am not familiar with kits available in Europe. For a 2-way with good controlled bass, I would suggest looking at a kit using Scan-Speak 18W/8545 or similar 7" Scan-Speak, or even Usher 7" woofers. In US, www.northcreekmusic.com has a nice 2 way kit with 18W/8545 Borelais or something like that. I think you can order the plans and buy the drivers locally, they should have a Scan-speak 18W/8545 and Scan-Speak 9500 tweeter combination.
What to do when one has a loudspeaker with an insufficient Qts at hand ? If you are just a bit skilled with electronics, you can use an amplifier with a negative output resistance. For trials, it can be built by adding a little of positive feedback around the amplifier : a 0.5 Ohm resistor senses the current through the loudspeaker and a dividing network is included at the non-inverting amplifier input, its lower rsistor being bootstraped by the 0.5 Ohm. Insert a polyswitch in the speaker path. Note that it's none less than Paul Voigt, Neville Thiele and some others who sugested the technique. The Qts value can easily divided by two.
Beppe,
when you look for bass elements you should look at Qts value to be around 0,35-0,40 for a vented box.
For a 8" woofer VAS should be around 50-70 litre and FS around 30-35 Hz at least, and last thing but not the least is sensitivity, preferably around 90 dB for 1 watt into the speaker.
If you find all these valuse for an element go for it and you WILL get bass.
The amplifier is of an order of magnitude less important in this matter as wrong values for an element will give 100 times worser results than any descent amplifier, so don't worry for the amplifier in the first room!
The Dynaudio element you have just simply and plain said is bad, the awfull high Qts around 0,8 is not at all sutiable for closed or vented speaker within sensible box volumes, it's probably much better for a transmission line but that will yield a big box as well and is more difficult to tune as it is verry important how much and where in the pipe you put the damping material etc. so that's not really a beginners topology to start with.
Are your D 21's for sale? If so are they the horn loaded ones or do you have more exactely the D 21-AF?
Cheers Michael
when you look for bass elements you should look at Qts value to be around 0,35-0,40 for a vented box.
For a 8" woofer VAS should be around 50-70 litre and FS around 30-35 Hz at least, and last thing but not the least is sensitivity, preferably around 90 dB for 1 watt into the speaker.
If you find all these valuse for an element go for it and you WILL get bass.
The amplifier is of an order of magnitude less important in this matter as wrong values for an element will give 100 times worser results than any descent amplifier, so don't worry for the amplifier in the first room!
The Dynaudio element you have just simply and plain said is bad, the awfull high Qts around 0,8 is not at all sutiable for closed or vented speaker within sensible box volumes, it's probably much better for a transmission line but that will yield a big box as well and is more difficult to tune as it is verry important how much and where in the pipe you put the damping material etc. so that's not really a beginners topology to start with.
Are your D 21's for sale? If so are they the horn loaded ones or do you have more exactely the D 21-AF?
Cheers Michael
Time to hit the reset button.
1. The speakers HAVE performed to Beppe's satisfaction.
2. A borrowed amplifier was the cause of the change.
3. The borrowed amplifier was considerably higher power, suggesting that more current helps the situation. This may be because the Damping Factor of the smaller amplifier changes for the worse when the amplifier is current limited.
4. The simulations both indicate that the drivers will, at best, exhibit a bit of boominess. (I'd expect room placement to have an effect on this.)
5. Skills and budget are limited.
Options.
1. Try to modestly improve damping by replacing the inductor with one with lower DC resisitance.
1.1 This will not improve the situation when the amplifier current limits.
1.2 Inexpensive and mildly educational.
1.3 Before buying, be sure that the DC resistance really is lower in the new inductor.
2. Modify the amplifier, by increasing the power supply.
2.1 Requires skills that may not be available.
2.2 There is no assurance that the amplifier output stage can handle the increased current.
3. Move the existing system into a larger box.
3.1 Lack of woodworking skills and tools may prevent this.??
3.2 There is still apt to be some boom, with a +2 to +3 dB peak. Perhaps room placement could help this.
4. Keep the existing box, and change woofer type.
4.1 Less expensive than changing amplifiers probably.
4.2 Requires crossover design skills that are probably not available.
5. Buy a driver/crossover kit, and install in the existing boxes.
5.1 Cost is a consideration, but could work.
5.2 Perhaps the existing drivers could be sold to help with the cost issue.
6. Buy an amplifier.
6.1 Cost is an obstacle. Perhaps old amp could be sold for enough to defray cost. A used amplifier would also help cost.
6.2 Listening to ensure system compatibility before purchase would be required. We really don't know if power/current is actually the reason for the improved performance.
7. Experiment with more radical placement changes than have been tried. For example a meter above the floor, and > a meter away from walls.
7.1 It's free.
7.2 It's educational.
7.3 May have been done.
7.4 May not work, as the problem is not uniform with level.
As far as I know, those are the options. None is perfect, and the ones more likely to work require more money and/or skills and time.
And finally, it wouldn't be a bad idea for those who are trying to help to read the entire thread.
1. The speakers HAVE performed to Beppe's satisfaction.
2. A borrowed amplifier was the cause of the change.
3. The borrowed amplifier was considerably higher power, suggesting that more current helps the situation. This may be because the Damping Factor of the smaller amplifier changes for the worse when the amplifier is current limited.
4. The simulations both indicate that the drivers will, at best, exhibit a bit of boominess. (I'd expect room placement to have an effect on this.)
5. Skills and budget are limited.
Options.
1. Try to modestly improve damping by replacing the inductor with one with lower DC resisitance.
1.1 This will not improve the situation when the amplifier current limits.
1.2 Inexpensive and mildly educational.
1.3 Before buying, be sure that the DC resistance really is lower in the new inductor.
2. Modify the amplifier, by increasing the power supply.
2.1 Requires skills that may not be available.
2.2 There is no assurance that the amplifier output stage can handle the increased current.
3. Move the existing system into a larger box.
3.1 Lack of woodworking skills and tools may prevent this.??
3.2 There is still apt to be some boom, with a +2 to +3 dB peak. Perhaps room placement could help this.
4. Keep the existing box, and change woofer type.
4.1 Less expensive than changing amplifiers probably.
4.2 Requires crossover design skills that are probably not available.
5. Buy a driver/crossover kit, and install in the existing boxes.
5.1 Cost is a consideration, but could work.
5.2 Perhaps the existing drivers could be sold to help with the cost issue.
6. Buy an amplifier.
6.1 Cost is an obstacle. Perhaps old amp could be sold for enough to defray cost. A used amplifier would also help cost.
6.2 Listening to ensure system compatibility before purchase would be required. We really don't know if power/current is actually the reason for the improved performance.
7. Experiment with more radical placement changes than have been tried. For example a meter above the floor, and > a meter away from walls.
7.1 It's free.
7.2 It's educational.
7.3 May have been done.
7.4 May not work, as the problem is not uniform with level.
As far as I know, those are the options. None is perfect, and the ones more likely to work require more money and/or skills and time.
And finally, it wouldn't be a bad idea for those who are trying to help to read the entire thread.
sreten said:Hi,
the smaller speakers (~ 27L) are not surprisingly even worse.
I've also shown the response for if the 24W-75 had Qts=0.35.
/sreten.
Dear Mr. Sreten,
thank you again for you kind and helpful advice.
I wonder how a such famous brand could make such poorly performing speakers and drivers.
I am litteraly astonished.
I bought them completely ignorant of this shortcomings, and my choise was based on the great reputation of the brand.
I am quite disappointed.
I also think that they were quite expensive.
Thank you very much for your kind and valuable advice.
Kind regards,
beppe
Dear Friends,
I would like to thank all of you sincerely for your very kind and valuable support in my "adventure" with these speakers.
As you see I am very ignorant on the topic of speakers design but one evidence seems to emerge without doubt to me:
" Both the designs are fundamentally flawed !".
I am more than convinced now but from a brand like Dynaudio this is quite unbelievable and even shocking.
If I understand well most of the problems come from the woofers' bad parameteres.
I could understand that. A bad designed driver.
But the fact that Dynaudio put a driver of this dimension in a box clearly undersized, well ....
Now I am here with some used raw parts that I would like to throw away from the window.
With your extremely kind, friendly and valuable help I have perfectly understood that, at this point, a change of speaker is just mandatory, before considering any other move.
First of all I have to be honest.
I do not think to have the needed skills to build a DIY speaker from the scratch.
Then I know that the following question is OFF TOPIC here and please feel free not to answer.
So my question is: could you kindly suggest me any "well" designed commercial speaker (that I can find used, also vintage could be very good) that could give me a nice sound without being a too demanding load for the amplifier (i.e. easy to drive) ?
I could give up to the lower bass under 60Hz but I would like to get an idea of soundstage reproduction.
At maximum I could try to do on them some mods you recommend in order to improve their performance.
I understand that this question is against the spirit of this site but I am extremely confused at this point and I would not like to go on filling my home with useless boxes.
Thank you very much again for your extremely kind, usefull and very appreciated help.
Best wishes,
beppe
I would like to thank all of you sincerely for your very kind and valuable support in my "adventure" with these speakers.
As you see I am very ignorant on the topic of speakers design but one evidence seems to emerge without doubt to me:
" Both the designs are fundamentally flawed !".
I am more than convinced now but from a brand like Dynaudio this is quite unbelievable and even shocking.
If I understand well most of the problems come from the woofers' bad parameteres.
I could understand that. A bad designed driver.
But the fact that Dynaudio put a driver of this dimension in a box clearly undersized, well ....
Now I am here with some used raw parts that I would like to throw away from the window.
With your extremely kind, friendly and valuable help I have perfectly understood that, at this point, a change of speaker is just mandatory, before considering any other move.
First of all I have to be honest.
I do not think to have the needed skills to build a DIY speaker from the scratch.
Then I know that the following question is OFF TOPIC here and please feel free not to answer.
So my question is: could you kindly suggest me any "well" designed commercial speaker (that I can find used, also vintage could be very good) that could give me a nice sound without being a too demanding load for the amplifier (i.e. easy to drive) ?
I could give up to the lower bass under 60Hz but I would like to get an idea of soundstage reproduction.
At maximum I could try to do on them some mods you recommend in order to improve their performance.
I understand that this question is against the spirit of this site but I am extremely confused at this point and I would not like to go on filling my home with useless boxes.
Thank you very much again for your extremely kind, usefull and very appreciated help.
Best wishes,
beppe
What I would do if this was my speaker.
8.0 Keep exisiting setup and add a bi-amp subwoofer as funds permit.
8.1) Add subwoofer or two with active xover. Look at plate amps to allow built in crossovers if limited technical assistance is available.
8.2) Set crossover with -12 db/oct after the 3 dB peak of the 24w-75 this will fix a number of problems with this driver in the smallish box. This will fix the bass peaking that will always exist given Qts > 0.8. Thusly Xmax will then be lower allowing better distortion performance.
8.3) Adjust new system gain/s setting given the new crossover point allowing for room gain and placement.
8.0 Keep exisiting setup and add a bi-amp subwoofer as funds permit.
8.1) Add subwoofer or two with active xover. Look at plate amps to allow built in crossovers if limited technical assistance is available.
8.2) Set crossover with -12 db/oct after the 3 dB peak of the 24w-75 this will fix a number of problems with this driver in the smallish box. This will fix the bass peaking that will always exist given Qts > 0.8. Thusly Xmax will then be lower allowing better distortion performance.
8.3) Adjust new system gain/s setting given the new crossover point allowing for room gain and placement.
Beppe, when somebody suggested negative resistance I’m your man!
I suggested to a man with Tannoys that he could try Don Keeles 6th order alignment and a similar reasoning applies to your speakers
Advantages are a small box with low excursion for the driver
You tune the box with a port to fb (Hz)
You could modify the variovent aperture to a proper port tube
You add a second order filter with a 6dB boost peaking at faux
Keeles equations are:
fb=f3=faux =0.3fs/Qts
and Vb = 4.1Qts^2 Vas
So for your 37 litre box
37/88.2= 4.1Qts^2
From which you need a Qts of 0.32
and f3 =0.3*33/0.32= 30.9Hz which is the 3db down point, the box tuning frequency and also the filter peak frequency.
Now you can get a Qts of 0.32 by using an amplifier with negative output resistance. This also improves the damping since you are effectively partially shorting out the voice coil.
The negative resistance can be done with an op-amp plus a few resistors. If you use a dual op-amp you can implement the 2nd order filter as well.
I am looking at the circuits of your amps to see if the circuit could be interfaced with them.
I have used this technique with some Morel drivers, a cousin of the Dynaudios and the system works well.
I suggested to a man with Tannoys that he could try Don Keeles 6th order alignment and a similar reasoning applies to your speakers
Advantages are a small box with low excursion for the driver
You tune the box with a port to fb (Hz)
You could modify the variovent aperture to a proper port tube
You add a second order filter with a 6dB boost peaking at faux
Keeles equations are:
fb=f3=faux =0.3fs/Qts
and Vb = 4.1Qts^2 Vas
So for your 37 litre box
37/88.2= 4.1Qts^2
From which you need a Qts of 0.32
and f3 =0.3*33/0.32= 30.9Hz which is the 3db down point, the box tuning frequency and also the filter peak frequency.
Now you can get a Qts of 0.32 by using an amplifier with negative output resistance. This also improves the damping since you are effectively partially shorting out the voice coil.
The negative resistance can be done with an op-amp plus a few resistors. If you use a dual op-amp you can implement the 2nd order filter as well.
I am looking at the circuits of your amps to see if the circuit could be interfaced with them.
I have used this technique with some Morel drivers, a cousin of the Dynaudios and the system works well.
There are too many good brands and models out there; and names listed here should ONLY suggest what should be on your listening list.
It's your hobby, your money, your choice of music, your room, your system, and finally, your ears. ONLY by listening, preferably in your room, can you be sure that your choice is correct for you.
Listening is painful. If you have a good dealer in your area, he is unlikely to carry more than 2 or 3 brands that would be suitable. And his selection of used speakers is apt to be even smaller. Even so, there is no substitute. People choose different music, play at different volumes, in different rooms, with different equipment, and different tastes; trust no one
except yourself, or a friend whom you KNOW has tastes similar to yours.
Your Dynaudios were apparently designed with a different market in mind; small, with boomy bass to compensate? Small, but for systems with fancier amplifiers? After all, you did get them to sound good once. And so you can sell them with clear conscience to a suitable purchaser.
With all that said, every Sonus Faber speaker system I have ever heard was musical.
It's your hobby, your money, your choice of music, your room, your system, and finally, your ears. ONLY by listening, preferably in your room, can you be sure that your choice is correct for you.
Listening is painful. If you have a good dealer in your area, he is unlikely to carry more than 2 or 3 brands that would be suitable. And his selection of used speakers is apt to be even smaller. Even so, there is no substitute. People choose different music, play at different volumes, in different rooms, with different equipment, and different tastes; trust no one
except yourself, or a friend whom you KNOW has tastes similar to yours. Your Dynaudios were apparently designed with a different market in mind; small, with boomy bass to compensate? Small, but for systems with fancier amplifiers? After all, you did get them to sound good once. And so you can sell them with clear conscience to a suitable purchaser.
With all that said, every Sonus Faber speaker system I have ever heard was musical.
I agree with Crumudgeon, but emphasize listening in YOUR room whole heartedly. Your room, amplifier, CD Player, cables, power filtering device (if any), couch (with a worn number for thread count), flooring, etc, etc. you get the point.
It's the only way to compare speakers, this is another reason why I built my own--I couldn't find any manufacturers willing to lend me speakers for around 30 days. Even with a CC. I'm going off on a tangent, so I'll just stop.
But, I must ask, what solution will you attempt? Amplifier, new speaker, new driver, etc??? Personally, your easiest and simplest solution is to buy an amplifier as some and I have already stated. Anyhow, tell us how it goes!
PS, I listened to Paradigm Refrence speakers and they were very intimate and warm, but I'm Canadian and had to throw Paradigm in there.
It's the only way to compare speakers, this is another reason why I built my own--I couldn't find any manufacturers willing to lend me speakers for around 30 days. Even with a CC. I'm going off on a tangent, so I'll just stop.
But, I must ask, what solution will you attempt? Amplifier, new speaker, new driver, etc??? Personally, your easiest and simplest solution is to buy an amplifier as some and I have already stated. Anyhow, tell us how it goes!
PS, I listened to Paradigm Refrence speakers and they were very intimate and warm, but I'm Canadian and had to throw Paradigm in there.
consort_ee_um said:
Hi CEU,
I think your getting a bit carried away with yourself.
Whilst what you say is technically feasible it has one fundamental flaw.
That is :
the necessary negative impedance of the amplifier will interact
with the complex impedance of the complete speaker and
drastically alter levels in the midrange and treble regions.
The technique is ideal for active speakers and active subwoofers.
/sreten.inertial said:
Dear Inertial,
now the problem is clear: it is intrinsic with the drivers (woofers).
The use of a more powerful amp only mitigates the problem without solving it.
So a change of drivers (difficult) or of the speakers completely (easier and maybe more logical) is the way to go.
It took me quite a long time but in the end, and above all with the extremely kind and precious help of the Friends here, I can say I have understood the reason of my unsatisfaction.
Now I am open to suggestion for a nice (and not too expensive) 2 way bookshelf good with all kind of music (let's say "universal").
I sincerely thank you all.
My best wishes,
beppe
dear Beppe,
cause my bad english I have believed understand that Aloia or Alabarry was "solved" the problem of bass in your room and without
any other variable. I have understood bad.
I am skeptical about ADCOM because I have tested last year 5400 model, and bass was not good, to my ears.
Maybe old 545 was better. I don't know.
Just my personal point of view, of course.
Cheers,
Inertial
cause my bad english I have believed understand that Aloia or Alabarry was "solved" the problem of bass in your room and without
any other variable. I have understood bad.
I am skeptical about ADCOM because I have tested last year 5400 model, and bass was not good, to my ears.
Maybe old 545 was better. I don't know.
Just my personal point of view, of course.
Cheers,
Inertial
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