Not at all. Please, try by yourself, instead of reject things because you don't understand them, or because they are counter-intuitive. Then go back with your results. (You will notice clearly the change, in the acoustic response curve)
I'm often surprised to see the "believe/not believe" position of the hifi people, not a very scientific approach...
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...even when shunted by amp's output resistance? No way with my amps. Guaranteed.
Many treble units use fibreglass wadding to damp the back chambers. Just try adding a little more so it ju...ust touches the diaphragm. Use the very fine stuff. If it doesn't move the coil off centre, the answers are
No, no & no. But try for yourself.
Not sure why you want the damping material to provide restoring force but you can provide it by this very simple method.
_____________
I'm resisting but .....
Are you saying the free air corrected impedance remains corrected even when the unit is used in a bass reflex? Got some curves that show this?
My goodness.
What the hell your amps have to do here ? Even if they are 0 ohms source impedance ?
It is not only a question of damping. It is a question of phases and Q.
You are right on a point, a damped speaker (low impedance amp) will resonate with a lower peak at his FS. It is not the whole story.
Change the coil of a given speaker with an other of the same weight and more turns (i don't know the word in English for 'spires'), no mechanical change, then measure how the Thiele and Small parameters had changed and how different it behave in your vented or closed box, whatever your amp.....
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To remove suspension ring, then reduces fractioning forces...
Thanks a lot for your idea, i will try.
Not easy, need a little compression of the fiber wool in order it follows the membrane displacement, without leaving contact with the membrane....
I wonder too how fiberglass can behave with its own inertia at high frequencies...
I will try, but i do not promises. It supposes i can re-find in my cellar some Bruel & Kjaer old sheets, more than 15 years old, if they still exists, go figure...
What i can say is it removes few dbs in the low medium area and a little change too near the FS. Remember this review i published about the "Aeria system".
They wrote
"Those of you, familiar with the 416 Altec, recognize their beautiful transparency between 200 and 800 Hz, but those loudspeakers misses the weight and serious mass impact of a JBL 2215 for example. The Audio Dynamic transducer had found this ideal compromise between impressive sub-basses (it can nail you to the wall) and this desired transparency in the 300-600 Hz area without any side effect of "cardboard " cone."
They tribute-it to the speaker, the would have better tribute-it to the motional impedance compensation, but they do not knew anything about.
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It is in parallel with both speaker and your "compensating" network. I can do you easily even negative resistance from tube amp.
I will not spend my life to argue endless in forums, when i had provided all tracks to understand the principle. (some closed loop afraid-me ;-)
I will save your time, porting the followings at your exclusive attention.
- Don't even try, or try to understand.
- I am stupid, i don't know anything i'm talking about.
- All that is fake, and at the age of 67, i wrote that just to make my *pseudo* shining in an obscure thread of a foreign forum near people i don't even know.
- I use to melt big and expensive air coils and caps in my filters just because i have money to spend or because i'm too lazy to throw them in the trash can.
- I can't hear the differences, in so many speakers workshop, because, as all sound engineers, I'm deaf.
- I love to make people around me loosing their time and money.
For all the others, it is a gift.
For you think about that, and , please, do not take my ironic humor too bad, take-it with a pinch of salt .
Respect, mr.Wurcer, you can recognize your nice babies at first sight, even in very low resolution avatars. I'm impressed.
As i was with so many good sounding current feedback op amps from A.D. (They are many in my system)
Sad to see many of them disappear one after the other from catalogs with this mention :"Obsolete".
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In principle, an amplifier that provides proper damping (a source impedance very small compared to load impedance) removes any effects of a paralleled passive impedance compensating network. That's the breaks.
Thanks,
Chris
Thank-you. (Il love the "proper damping")
I will neither use inductance compensation (Zobel) any more, too.
Talking about impedance, of course, all amps behave (sound and measure) the same, whatever the charge 150 or 6 ohms, the coils of the passive filters + Lp cables are 0 impedance, nobody never use attenuators for medium / tweeters...etc...
EOT for me.
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Take the same back from me (except the age, it's 55), and add that I don't have a diploma in electronics, don't have experience in design of electronics equipment, and don't know what I am talking about.
Also, add to the list with me Mr Kirchhoff who would be hundred percent agree with what I was saying.
Edit: as I said, it depends on the amp that drives the speaker. If the amp has almost zero ohm linear output resistance all that additions look like defibrillator for a corpse taken from a grave.
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Right: if you use active filters with a D amp right in the back of the speakers, i doubt any noticeable change.
... replace-it in the context i placed-it: passive filter in the enclosure, unknown amp and cables etc...
Don't you prefer too to calculate filters with a constant impedance load ? What about the group delay ? Don't you prefer your amp have a constant impedance as a charge ?
I think you argue for the pleasure of arguing. I live in a real world where "proper damping" does not often exists.
With the AERIA, as an example, the cabinets where driven with a very low impedance amp, right between the enclosures, with BIG cables between them, and very big wires diameters air coils in the passive filter. The with/without difference was obvious, both in listening and measurements. It is just an example between hundreds.
This time, real EOT for me.
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This thing about the quality of bass always gets me, people obsess about the most minute details of the construction of the speaker and crossover being all important. Yet, in my experience, the ability of the amplifying electronics to behave themselves is the crucial factor. I've just been to a hifi show where they had subwoofers with enough mass to crush a car, which didn't do anything for me. The one system that did the bass right had high quality drivers, no subwoofer, and a well made amplifier that had miles of headroom, able to drive the speakers as hard as people were game to turn up the wick ...
Frank
Frank
Exactly! When you design the speaker as a product, complete, to be liked by as many of potential buyers as you can, of course you will do all fool-proof things for that!
No, I don't. I calculate everything for the real life. I call it "Optimization".
And I don't care of impedances of speakers on any frequencies when they are _part_ of the whole system under my control. It is absolutely irrelevant, when I can correct all differences by digital thingy (all at once) instead of heating an air inside of speaker enclosures.
Currently I drive subwoofer horn under the floor by 200W amp, woofers (40-100 Hz) by 100W amps, arrays of 8 of 4.5" midranges (16 Ohm total) + 16 x 1" high/ 2" wide tweeters (32 Ohm total) from 100W amplifier. As you may see, if I feed all that amps by the same level of signals frequency response will be bumpy. Load impedance of all individual amps are very bumpy, I don't care. So I adjust levels according to SPLs (roughly), then digital Audyssey fine tunes the rest.
However it can't be called "fool-proof product for sale", since it needs fine tuning. But making each part of subsystem optimal you will never ever get optimal system. It is the axiom.
There were some German table radios from 1955-1965 that had small round (~30-50mm Dia) electrostatics, the construction of which fits exactly to your description. They worked fine (and the foam does not rust-disintegrate-after all these years)
Thank you for mentioning it. It was to be seen inside good speakers (AR and maybe ADVENT) in the past. A variation of this was a diagonally hanged, twisted damping foil.
R. Small has dealt with this. He analyses it as a small volume chamber which communicates with the rest of the enclosure volume through resistive frictional elements.
This technique too can be seen on old 1930-1950 full range speakers, mostly from Britain and Germany, albeit the "foil" realized with corrugated cotton cloth.
Wavebourn
If you mix your concrete with white carpenters glue (~10%-20% by weight) the mixture is self damped. It does not “ring” after drying. It also flows better and provides smoother surface finish. Much less crazing and hairline cracks.
You can add chopped glass fibers in the mix too for structural integrity.
George
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