Accuton 3-ways ?

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Jussi

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Joined 2003
#1
Hi,

Got a new project coming up and one strong candidate to midrange duty is C95-11 Accuton, two on each side in MTM configuration. Already have Dynaudio T330D Esotars for treble and thought to use single large woofer on each side in separated compartment for bass.

Bass is going to be dipole config. With separated enclosure I can turn them separately from mains and search best accuracy in room. Mains are going to have so called acoustic resistance cabinet and radiation pattern something between cardioid and hypercardioid.

As midrange I've looked up some candidates. Itself proven W18EX Excel is one, C95-11 another. Also considering some Peerless HDS and Seas standard models for budget variations. Crossover frequences around 100-150Hz and 2-2,5Khz.

Linkwitz didn't consider C92 that good in his tests before Phoenix project. Linear distorsion shows some energy storage. I assume this is a problem with suspension. C95 has somewhat different suspension. Rms is lower and Qms higher.

Does anyone have experience and maybe reliable response and distorsion measurements from this Accuton model?

Other comments, advices and recommendation are also very welcome.

Best regards,

Jussi
 
#2
I've heard the Esotars several times.. and they are not really suited to the accutons.

Instead look for a paper or carbon driver with an fs of at least 50 Hz..

Considering the Esotar's character and the desire to use 2 drivers (but keep the cost reasonable..) this is the driver I'd probably choose:

http://www.madisound.com/pdf/audax/hm130c0.pdf

They should complement the Esotars perfectly.

Note though that Audax is pulling out, so get'em while they are available.
 
#4
Jussi said:
Hi Scott,

What kind of character Esotars have? What about Accutons? Would W18EX be better match with Eso?

Thanks!

Jussi
Click to expand...


Sorry its taken me so long to reply (..computer down).

I've found the character is a bit softer (less of a sibilant "edge"), while still being quite transparent. (Its a fantastic driver.)

Neither the Accutons or the Seas (METAL) drivers should be used. You could use a Seas paper design or their poly coated paper (but see what I've written below).

For instance I've heard an older Kharma loudspeaker (3-way) that used the scan speak revelator (similar in sound character to the esotar - though less transparent) with an accuton midrange. There was an audible discontinuity to the speaker both in terms of transparency and tonality (..and I'm pretty sure the difference in tonality was not due to freq. response problems) between the two drivers.

Now the Convergent Audio Technology (CAT) reference speaker I've heard specifically uses the esotar while using either a poly only (or a poly coated) seas driver with the excel driver assembly for the midrange (in an MTM). This was considerably better, however the seas was just a little less transparent and overdamped tonally in comparison to the esotar.

Again, I think the better driver match would be the Audax I linked to. Combine this driver in parallel (the M & M of the MTM) with inductors (in the crossover) that have a bit of resistance, (smaller guage wire), to not only raise the impeadance of the midrange back up to esotar, but to also decrease the midrange's gain in effeciency down to the esotar.
 
#5
An important note:

If you do use the Audax's, do NOT place damping material anywhere near the driver except for possibly a minor amount on the driver's frame and magnet.

FAR preferable would be to use a silicone borscillate paint - both on the driver's frame and magnet and on surface interiors of the box in MULTIPLE coats. (essentially a latex paint with ceramic micro-spheres that absorb sound.)

Here is the additive:

http://www.hytechsales.com/insulating_paint_additives.html

..you could combine it with any paint, but considering the price and favorable porosity of primer paint, I'd use a latex primer with it.

CAE also makes it as paint called TempCoat, but it costs more and you don't get to vary the concentration of micro-spheres (..more is better up to a point.).
 
#11
I have an Accuton C90 and the Esotar tweeters. They are both wonderful drivers: transparent, detailed, distorsion free, 93+db sensitivity, ...
But I think that they are not made to be used together. The Esotar performs really better with a more full bodied mid or midbass (Audiotechnology for Rockport, Scanspeak for Merlin, Morel for EgglestonWorks) where the whole sound is capped by its delicaticy and airiness.
I am also in the search of the best matched tweeter for Accuton mid. I have tried ribbons (LCY): better but not perfect (but I am only at the beginning). I also search infos on the Accuton C13.
Someone mentions the Mundorf AMT (http://www.mundorf.com/downloads/info-news/MUNDORF-News.1-2005.pdf) but I have no report at this time.
Christophe
 
#12
Jussi said:
Hi Scott,

What about general recommendations of SOTA MTM 7" + dome tweeter?

Thanks !

Jussi
Click to expand...


This depends on how steep the filter is and what the freq. of the cross-point is.

I'd say LR 4th order just under 2 kHz would be a decent general recommendation for such a large diameter (when considering off-axis behaviour and cone "break-up").

________________________________________

The accuton is more transparent. The "material" tonal difference is the driver's diaphram and its relationship between propagation velocity and internal loss. Poly has a low propagation velocity and high internal loss. Corundum (the accuton material) is esentially the opposite - it has a high propagation velocity and a moderatly low internal loss.

When you include the modulus of rigidity with propagation velocity, carbon fiber is more like the silk driver of the esotar (which also has high rigidity in its structural configuration).

For instance: carbon fiber has about half of the internal loss of poly, BUT it has almost 10 TIMES the propagation velocity (when factoring rigidity). Standard paper (vs. carbon fiber) is almost the same with regard to internal loss (slight less though), but it is only about a quarter of the propagation velocity. When comparing magnesium to carbon fiber, carbon fiber has only a slightly higher propagation velocity (and rigidity) vs. magnesium, BUT it has an internal loss that is more than 6 times as high.

Of course diaphram material is NOT the only factor (not by a long shot), but in general drivers with similar diaphram parameters have similar tonal qualities.

So long story short.. No I don't think that Kharma was poorly executed, but their driver selection was flawed (..at least tonally).
 
#13
cyclo said:
I have an Accuton C90 and the Esotar tweeters. They are both wonderful drivers: transparent, detailed, distorsion free, 93+db sensitivity, ...
But I think that they are not made to be used together. The Esotar performs really better with a more full bodied mid or midbass (Audiotechnology for Rockport, Scanspeak for Merlin, Morel for EgglestonWorks) where the whole sound is capped by its delicaticy and airiness.
I am also in the search of the best matched tweeter for Accuton mid. I have tried ribbons (LCY): better but not perfect (but I am only at the beginning). I also search infos on the Accuton C13.
Someone mentions the Mundorf AMT (http://www.mundorf.com/downloads/info-news/MUNDORF-News.1-2005.pdf) but I have no report at this time.
Christophe
Click to expand...


The LCY ribbon (if crossed over correctly), would be near perfect..

if:

they had matching eff.s (member Zaph found that it was 5-6 db lower than spec.), and

you had a steep low crossover (say LR 4th 3kHz), and

you had a amplifier with a high ouput impeadance (at least 8 ohms, but better at 14-15 ohms).
 
#15
I agree: the LCY is transparent and lively and performs well with the accuton sound. But it lacks the refinement and delicacy of the Esotar. The sensitivity is really low for a ribbon and I have founded that the frequency response is far from flat (especially if you look at the published one!). But I have to admit that I am only working with it for only 2 weeks (now crossed at 4 kHz 4th order Butterworth).
Christophe
 
#16
cyclo said:
But it lacks the refinement and delicacy of the Esotar.
Click to expand...

This is where traditional "damping factor" comes in.. or in otherwords my last statment on needing an amplifier with a high output impeadance. High damping factors with ribbons also "rob" imaging of "palpability" or "density" and make the locus of imaging too "tight" and "pin-point" in nature.
 
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