Why is this woofer so difficult to drive properly.

[beppe61]

Hi,
there is a lot of opinion in this thread and not much real practical advice.
If the Morel drivers fit the cut-outs in your speakers I strongly recommend that you fit these drivers, they will drastically change the bass performance.
You are lucky that an almost "perfect" driver exists to fit as a replacement.
The resultant new bass alignment will have far less upper bass so they will become room gain friendly, consequently low bass will sound much better.
🙂/sreten.

Dear Mr. Sreten,

this is indeed the most interesting option and could save me from rebuilding a complete speaker.
With some more studies about crossovers design I could point out the required adjustements to the existing crossovers.
That would be my fist option: replacing woofers with suitable alternatives.

Thank you sincerely again.
Kind regards,

beppe

 

[forr]

Negative resistance output

Here is an experimental circuit of an amplifier with a negative resistance output to lower the Qe of a loudspeaker. It uses a bootstrap around a sensing resistor and only two other resistors.
Caution : include a polyswith in the loudspeaker path.

When current I increases from 0 A to 1 A, voltage Vout increases from 10 V to 15 V. This means that the output resistance of the amplifier is negative, equal to -5 Ohms. Scale according to your needs. Some protection is necessary because if current approaches 2 A, the system becomes instable.

 

[fiak]

tinitus,
Right, even today you can see 8 to 12 in. units used as mid woofers in 4 way applications.
sreten,
I definitely respect your knowledge (as I do for everybody) and your willing to help. The scenario has to do with the threads posted by myself. Sometimes I try to give a light appeal to them.
I liked the surreal respond of Bose.
beppe,
Most of the things you ask me are already answered by others also.
The loudspeakers you mention belong to the high end category, yours not.
I suppose you heard these speakers before buying them, why you blame the engineers now.
You pick a pair of loudspeakers because you like their sound, it is that simple.
Sign off.

 

[redunzelizer]

I love this thread

I'm starting to get some questionable fun out of this one too... 😉

Nevertheless I would stress the fact that this kind of woofer would be difficult to drive "properly" for any power amp.
This is a "wrong" driver.

No. There are only wrong enclosures & "engineers".

Please Sir. Can we design and build a driver rightly firstly?
I understand that the current Dynaudio production has addressed the magnet decreasing the Qts as a result (good move Dynaudio. Bravo!).

What's the "rightly driver" drive then? One that can only be handled by unexperienced people?

you are very right. Speaker design is so difficult that even at Dynaudio they have not understood completelythe the principles behind it.

Who are you (and we?) to judge that?

I think that the influence of Variovent is marginal after all.

No. Wrong again.

Speaker design is difficult, yes, just like any other technical design. And then there is also taste and intention. So Dynaudio has not understood speaker design, just because these don't match your taste?

Beppe, you ran into the worst imaginable situation that any beginner with loudspeakers can run into. You started getting interested in the topic and happened to have one of the very difficult drivers to handle at your hands.

A problem is, that this thread has quite a bad signal to noise ratio, putting actual experience and working solutions in relations to "the usual suspect fairy tale advice". Of course you're having a hard time understanding and filtering out the real usefull stuff inbetween all the crackle and hiss.

Nevertheless you repeatedly blame the manufacturer for your insufficient (to *your* taste) results. As long as you do not want to understand that a driver alone is nothing, as there is always an implementation, including enclosure and crossover, you will not succeed. And this "implementation" will be (had been) targeted at a certain goal, be it commercial or audiophile, which might not at all be yours.

Beppe, I have worked successfully (for the given targets) with these drivers (and variovents) more than once but I refuse to give any further advice, as long as I smell such an uneven attitude on your side. After all, there would be a chance of giving you some more useful advice and you might then blame me for something I am not at all responsible for.

regards


P.S.
Had IRF044s in my output stage and changed these to 2SC5200.
Higher transconductance is "better" after all, isn't it?
That Amp sparked, smoked, and terminally blew up.

Beppe's conclusion: Toshiba can't make Transistors!

 

[Curmudgeon]

Oh, c'mon everybody, let's stop the chest beating, the fingerpointing, the backstabbing, and instead try to help Beppe solve his problem. This a hobby, something people do for FUN. English is not the first language of many of the posters, and who knows what misunderstandings are lurking? Although it does help if the entire thread has been read.

To exchange drivers, beppe, there are several considerations. You're not in a position (yet?) to do crossover design, nor extensive woodworking.

So, some suggested points for you to consider;
1. The woofer efficiency and impedance should match the current woofer's.
2. The manufacturer's response curve should be believable, and show no high frequency peaks. Forum members, between them all, have a lot of experience, if only with a few manufacturers each.
3. You should ask forum members to use a bass box simulator to see how well a proposed driver will work in your existing cabinets.
4. A schematic of the crossover would help.

Spec sheets for the midrange would be a big help. IIRC, the dome mid had to be crossed over at 5-800 Hz (???), so a woofer that is comfortable above the usual 150-300 Hz crossover point is needed.

And good luck.

 

[Eva]

P.S.
Had IRF044s in my output stage and changed these to 2SC5200.
Higher transconductance is "better" after all, isn't it?
That Amp sparked, smoked, and terminally blew up.

Beppe's conclusion: Toshiba can't make Transistors!

😀😀😀😀😀😀😀😀😀

Concerning the negative impedance approach, it works but becomes unstable when enough amount is added to nearly cancel the DC resistance of the speaker. It has definitely to be used with care.

 

[Bose(o)]

Step 1: Sell Dynaudios.
Step 2: Sell Amp
Step 3: Start all over, with commercial speakers or DIY jobs.

Or, at least do something.

The only reason, Beppe, why I haven't really focused on the speakers/cross over/relationship is that I took the latter into my head all at once. It took my young mind years to truly UNDERSTAND what was going on when I played music through my speakers. I feel, that if someone without the background in physics and math that I have, shouldn't need to know this, but at least get a working idea of the numbers used in speaker design. As basic as possible, KISS, if you will. (Keep It Simple Stupid).

The one question I feel that should have also been asked is this; Beppe, have you heard a speaker that you liked, or like more than your current ones? Or, rather, a speaker/amp combo that you liked? From this, one could infer that maybe he has "adjusted" to the sound that he has.

Regardless, keep reading and learning Beppe, you're part of the best forum in the world. However, with the gobs of knowledge here, you must first depend on yourself. Remember, understanding always comes from within regardless of teacher, books or, school.

 

[rcavictim]

I've got an article in one of my old electronics mags from the 50's that covers the development of a negative resiatance vacuum tube hi-fi amplifier. It has all details needed to duplicate it if one wanted to try something on the edge. The idea to me forms mental images like a jet fighter plane with foirward swept wings.

 

[beppe61]

....
:

Dear Sir,

all right. I admit. I have been carried away by my own delusion.
I reset my brain. I take a breath.
As I said at the beginning I bought these speakers only on the basis od the brand's reputation, completely ignorant of the techical aspect.
Now from experts I learn that this particular woofer to work properly should be mounted open-baffle.
I cannot immagine that a Dynaudio do not know this.
Now the question is: why did they mount it in a wrong enclosure?
I would call this a wrong speaker by design.
Am I wrong?
Actually Dynaudio modded their drivers in the following series, addressing the magnets I think, and making them bigger.
So they feel the "need" to do so, maybe hearing some unsatisfaction from their customers?

To end all my ramblings the fact that these models are so uncommon speaks for itself at the end.
Yes. I could sell it to another poor guy but I do not feel like doing so.

Thank you very much and kind regards.
beppe

 

[inertial]

hi beppe,

An old and symple method to lower the Qt can be this:
Add stuffing near the woofer. This add "loss".
To be sure dacron do not enter in the frame-holes, you can
turn two laps of very light "gauze" directly on the frame.
Than gradually you can add dacron into the box and insert the
woofer.
Try and listen, you can expect a reduction of the peak at Fc.
Maybe it can be help....

cheers,
Inertial

 

[beppe61]

hi beppe,
...
An old and symple method to lower the Qt can be this:
....
Add stuffing near the woofer. cheers,
Inertial

Dear Inertial,

if I understand well do you suggest a "patch" ?
I will think about that.
Thank you very much and regards,

beppe

 

[tinitus]

Hi beppe, I am sure you will learn that this is not the last dissapointment - of which there are a lot in hifi hobby

And to why Dynaudio does such a thing - well, as said not very uncommon in this world - I think there are not very many truly well built commercial speakers, not even among the very expencive ones.

Untill now only bass has been commented - what about the overall sound of the speaker

And I would like to know if bass problem occurs on certain type of music - I can tell you, I have a wonderfull speaker, but I simply cant play a lot of modern music - simply too booomy

 

[beppe61]

Hi beppe,
1) I am sure you will learn that this is not the last dissapointment - of which there are a lot in hifi hobby
2) And to why Dynaudio does such a thing - well, as said not very uncommon in this world -
3) I think there are not very many truly well built commercial speakers, not even among the very expencive ones.
4) Untill now only bass has been commented - what about the overall sound of the speaker
5) And I would like to know if bass problem occurs on certain type of music - I can tell you, I have a wonderfull speaker, but I simply cant play a lot of modern music - simply too booomy

Dear Mr. Tinitus,
thank you for your kind reply and valuable reply.
Let me reply hereunder.
1) You are very right. But well I would prefer, anyway, to set-up a system that can give me a little pleasure. Life is short afterall.
2) My comments wanted to be constructive. Withe some driver/enclosure mods the spaeker could be really good.
3) Well this is quite of a surprise for me.
With all the design tools available today it seems very strange to me. Strange commercial policy. Maybe is all about marketing in the end?
4) From the mid up very good. Clean and detailed and natural.
very good really. Maybe the D28 helps here.
5) of course on rock/pop over any other kind.
When a powerful but fast bass and controlled is needed.
But I listen to everything in the end.

Thank you very much.
Kind regards,

beppe

 

[tinitus]

Hi Beppe, well, playing loud rock/pop will be demanding for very many speakers

Still, no speaker with a single 7-8" woofer will never be able to do what you expect of it, I think

There is a tendensy in modern recordings to boost midbass - producers know that many young people like this bombom thing - and it is said that many recordings are made for car stereo - strange world.

 

[beppe61]

Hi Beppe, well, playing loud rock/pop will be demanding for very many speakers
Still, no speaker with a single 7-8" woofer will never be able to do what you expect of it, I think
There is a tendensy in modern recordings to boost midbass - producers know that many young people like this bombom thing - and it is said that many recordings are made for car stereo - strange world.

Hello Tinitus,

just to give an example in the weekend I paid a visit to a friend of mine and we listened to an old pair of JBL bookshelf, the L16.
The bass in my opinion was just fine and enjoyable.
It sports a 8" woofer (2" coil, alnico magnet. A nice driver).
I liked it very much.
Actually with a piece with percussions it was even exciting.
And if a speaker cannot convey the emotion that is in the music it just does not do its job.

Kind regards,
beppe

 

[tinitus]

Hi, thats kind of funny Beppe, because I just had a thought you might like one of the better JBL.

And I dont think you should feel bad about passing your Dynaudio on to another, if he knows how to handle it - it obviously is no "rocker", but favours a certain kind of music.

best regards

 

[beppe61]

1) Hi, thats kind of funny Beppe, because I just had a thought you might like one of the better JBL.
2) And I dont think you should feel bad about passing your Dynaudio on to another, if he knows how to handle it - it obviously is no "rocker", but favours a certain kind of music.

best regards

Dear Tinitus,
regarding 1) yes I liked the JBL little 2 way L16 a lot.
By the way I understand the tweeter is not very good.
The bass was exciting.
2) Nevertheless I wonder what makes a speaker a "rocker".
I believe that a lot has to do with the woofer qualities.
A question: if you had to build a speaker for rock/pop which kind of woofer would you choose?
I find the ability "to rock" very exciting.

Thanks and regards,

beppe

 

[tinitus]

Hi Beppe, being a DIY and not knowing much anout commercial things I may not be the one to guide you
But doing rock only makes it a lot simpler - and should it play classical too will be very difficult
But things can be very complicated - the JBL of your friend may not be as good in YOUR "invironment" - I recall you liked your Dynaudio in another setup
So being very specific is not that easy

There is one which has interested me for some time - those big COAXIAL speakers - if it works it is cheap and simple and could do as a good "rocker" - but I have no experince with those

I hope someone else can be more helpfull

By the way - it can be very important how you place your Dynaudio in your room - maybe you can make us a "drawing" of your "setup" - and we maybe can guide you better.

 

[tinitus]

Hey, you might also like this BR Fostex thing - but its DIY, although moderate

http://www.tnt-audio.com/clinica/bfb_e.html

Or there are other more expencive fullrangers with more delicate sound - others will know more about this

😉

 

[beppe61]

1) Hi Beppe,
being a DIY and not knowing much anout commercial things I may not be the one to guide you
2) But doing rock only makes it a lot simpler - and should it play classical too will be very difficult
3) But things can be very complicated - the JBL of your friend may not be as good in YOUR "invironment" -
4) I recall you liked your Dynaudio in another setup
So being very specific is not that easy
5) There is one which has interested me for some time - those big COAXIAL speakers - if it works it is cheap and simple and could do as a good "rocker" - but I have no experince with those
I hope someone else can be more helpfull
6) By the way - it can be very important how you place your Dynaudio in your room - maybe you can make us a "drawing" of your "setup" - and we maybe can guide you better.

Hello Tinitus,
let me reply point by point to your valuable advice.
1) I think of DIY, maybe making a mistake, also as modding existing speakers.
Maybe a commercial bass reflex can be modified for a better response. A driver can be replaced with another one with good results.
For instance I understand that the woofers can be good in a open baffle arrangement.
So it is up to me to build another box open baffle or replace the bass driver and keep the high driver that is just fine.
Of course the "real" diy would be to build up from teh scratch but also modding I can learn something of useful.
For istance I understand that in those JBL L16 the tweeter is nothing special and I intend to replace it with a better one.
The woofer instead is very good, IMHO.
2) I am still convinced that a really good speaker should be good with different kind of music.
Nevertheless I am not looking for a high-end performance after all.
3) That is indeed a point. I will assess this.
4) Yes, but easy of drive in my vocabulary is a plus.
It frees me to use ordinary amps that I already have at hand.
5) are you talking of Tannoy maybe? I like extremely the idea.
Very interesting. I heard one from their Prestige series(expensive). Great imaging, focus and dynamic but a little directive in the highs because of the small horn placed in front of the tweeter. Nevertheless a very exciting speaker indeed.
6) of course placement plays a big role.
Actually I like very much speakers that are less depending on placement.
For instance I can stand dipoles. Their rear emission is very difficult to control.
I like speakers that can be placed close to the front wall without particular problems.
I always try to keep things simple as possible.

Thanks and regards,

beppe