Are you referring to low level resistance of the moving parts (forgot the official term)?
The TL1603 plots look good...
However, plots only tell one part of the story > not necessarily related to sound quality in the upper band of the range.
Mms is way too high relative to BL and the ribbed, fairly straight cone + accordion surround indicates high amounts of 'self damping'.
Which is confirmed by the gentle, early roll off, similar to some JBL's. There's a rising response, which is good, though I'd hesitate to use it up to 800-1000 Hz. There's a good chance the woofer sounds rather musty > 500 Hz.
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To put it simply: how logical is it to couple a mid/high driver with an ultra stiff and strong (tensile strength) diaphragm of only 1 gram with a very powerful motor structure 'seamlessly' to a heavy, spongy cone that also is driven by relatively weak motor?
The TD40.. compression drivers are ultra efficient, while the TL1603 is relatively inefficient (1.81%).
There are all kinds of theoretical physics explanations to 'legitimize' this, but the problem is that the drivers have been developed in isolation. A loudspeaker system is more than the sum of its parts.
The TD40.. compression drivers are ultra efficient, while the TL1603 is relatively inefficient (1.81%).
There are all kinds of theoretical physics explanations to 'legitimize' this, but the problem is that the drivers have been developed in isolation. A loudspeaker system is more than the sum of its parts.
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Is it really the efficienty or the way the drivers fire into the impedance of air : The big cone drivers fire directly in air while many horns with deepness enough have a progressive air impedance load via the horn maybe ! It is maybe a first mismatch, no ?
I know very little but perhaps there should be always a 3 ways with compression drivers where the middle way is a horn loaded mid-bass to make the transition between, say the two or three first octave and th ecompression tweeter ?
However I am not sur OS wave guide suffer of the same mismatch ?
Maybe Dr Our great Dr Earl G. could enligth us ?
Anyway if I had a 15" or a 16" , I would not go further than 400 hz and 300 hz just by psychorigidity. The Altec A5 and A7 were specials with their wave guide and kicked in the mid-bass area (perhaps also because the way the vented load was setuped with no really low bass extension?)
I know very little but perhaps there should be always a 3 ways with compression drivers where the middle way is a horn loaded mid-bass to make the transition between, say the two or three first octave and th ecompression tweeter ?
However I am not sur OS wave guide suffer of the same mismatch ?
Maybe Dr Our great Dr Earl G. could enligth us ?
Anyway if I had a 15" or a 16" , I would not go further than 400 hz and 300 hz just by psychorigidity. The Altec A5 and A7 were specials with their wave guide and kicked in the mid-bass area (perhaps also because the way the vented load was setuped with no really low bass extension?)
There are some as good no ? One or two Davis Acoustics or at Fostex that copied the T&S. Look also at EMS drivers in France ; (Electro magnet System), maybe one Audax was near, certainly the big Focal W should be better ! I dunno if B&W eated the feets of the Altec in term of acoustic qualities !
I'm not really sure what you are asking.
I would agree that the region that you are talking about is critical and one that has to be paid attention to when using a large driver. That does not mean that it can't be done. The first thing that I looked at in a LF/Mid driver was how it "broke-up" - since they all do. I pretty much stopped looking past those specs as the others are all insignificant in comparison. My goal was one crossover above say 150 Hz. That means very wideband passbands and made the crossover choice rather high. But still it was doable despite being difficult.
No, sorry you are wrong. none of your listed drivers comes close to the qualities of an altec 416 in the a7. what a 416 possesses in midrange qualities is unique and unrivaled.
it was an open question as I haven't benchmarked them myself, if you had, you are a lucky one.
Also the Altec had magnet agging weakness problem due to the poor quality of their suppliers, I had read in Japan or a french forum, dunno remember...
Also the Altec had magnet agging weakness problem due to the poor quality of their suppliers, I had read in Japan or a french forum, dunno remember...
There is plenty to find in other threads.
There're no absolutes in this regard and I am merely sharing my personal view and not preaching gospel.
Many people are intensely happy with their Dynaudio compact 2-way monitors, while within 10 sec. I'm fed up with the overdamped port tuning.
The same goes for most speakers with plastic cones. And so on.
Moreover, many of these aspects fall outside the standard R&D domain.
Drivers today are developed with different objectives compared to, say, 80, 40, or even 20 years ago.
Earlier in this thread I quoted some examples of B&C drivers you're familiar with.
In terms of performance, there's actually no direct replacement for the DE500 within the current B&C range.
The same applies to the DE25.
A quote from ‘Loudspeakers, for music recording and reproduction’ by Philip Newell and Keith Holland:
“Some manufacturers have tried to sacrifice system sensitivity by lowering the magnet flux in order to lower the system Q. There is a strong ‘amplifier power in cheap’ lobby, who believe that lower efficiency systems can exhibit higher Qs, and hence can be extended in their low frequency range. What they often seem to fail to realise is that a heavier current in the voice coil and a lower power magnet will drastically alter the ratio of the fixed magnetic field to the variable magnet field. The much higher variable field due to the voice coil current can severely distort the position of the flux lines of the weak, permanent magnet, and give rise to loss of low level detail in the sound and increased levels of intermodulation distortion.”
An obvious solution then seems to lie in an overengineered magnet structure including modulation rings etc.
Fact is that a low Fs in a compact cabinet requires a heavy cone and a lot of Xmax...
Theoretically, such a woofer may be optimised, but practically and cost-wise this is not feasible.
Imo, flux density is an indicator of midrange quality along with efficiency, in remembrance of Josef Anton Hofmann.
“Some manufacturers have tried to sacrifice system sensitivity by lowering the magnet flux in order to lower the system Q. There is a strong ‘amplifier power in cheap’ lobby, who believe that lower efficiency systems can exhibit higher Qs, and hence can be extended in their low frequency range. What they often seem to fail to realise is that a heavier current in the voice coil and a lower power magnet will drastically alter the ratio of the fixed magnetic field to the variable magnet field. The much higher variable field due to the voice coil current can severely distort the position of the flux lines of the weak, permanent magnet, and give rise to loss of low level detail in the sound and increased levels of intermodulation distortion.”
An obvious solution then seems to lie in an overengineered magnet structure including modulation rings etc.
Fact is that a low Fs in a compact cabinet requires a heavy cone and a lot of Xmax...
Theoretically, such a woofer may be optimised, but practically and cost-wise this is not feasible.
Imo, flux density is an indicator of midrange quality along with efficiency, in remembrance of Josef Anton Hofmann.
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I thought that we were talking about mi/woofers?
And I agree with the above (Newell and Holland), low efficiency woofers are not a good choice. With multiple subs LF extension is not an issue.
And the DE250 was a very good replacement for the DE25 - that's what it was designed to do. I liked the DE500, but it did not have the HF extension of the DE250. (Not an issue with active Xover, like it is for passive.)
Perhaps because compression drivers are usually combined with woofers and it might be useful to give a few examples in the context of 'matching'?
The first generation DE250 perhaps, the later (post 2010) production is clearly less good/consistent.
This has been observed by both you and others in the past.