Anyone using a Class D amp w/ribbon tweeters?

@1graber2 

I am using ICEpower 25 ASP based mono blocks. One under each speaker. Literally. :) 

My ribbons are from Mundorf. Sound fabulous, but electrically VERY different than a ribbon.

Ribbons tend to be very low impedance, and need a matching transformer.

AMT's have no need for a transformer, and are almost purely resistors (relative to most drivers). 

Best,

E

@mapman 
interesting what you say about the Bel Canto C5i (same for the C7?), 
that has been on my list of "all in one" units to pick up 
and play with as an extra system in another room. 
I was worried that it might have some upper end grain.

@aolmrd1241 
Yeesh, this Merrill Class D monos are ridiculous! (aka awesome),
as described on the Merrill site, 

"Start with a 66 pound of Aircraft grade 6061 solid aluminum block. Delicately machine the chassis from this solid block isolation chambers to limit any sonic interference and minimize vibrations. Keep the walls 1 inches thick, to limit and absorb vibration. The result is a ..."

and I hear no top end sibilance

What I’ve heard is either two things in the upper/mid highs from Class-D, either sibilance as mapman mentions or an opaque whiteness.

This to me comes from "high power the low order switching noise output filters" either "set too high" which lets through too much of the switching noise (sibilant) and some audio band phase shifts, or "set too low" which hacks out most of the switching noise but also hacks into the audio frequencies upper mids ,highs (opaqueness) and creates not only attenuation but even larger phase shifts than the "too high" filter does.

The only way to fix this to me is to raise the switching frequencies much higher so the "high power low order output filter" can do it’s job properly without any effects down into the audio band. As Technics have started to do with the flagship SE-R1 with more twice the switching frequency of today, but at $30k aud and limited supply.

BTW you can see this switching frequency noise on Class-D amps in Stereophile bench tests that sits on the 10khz square waves, like a buzz saw across the top of the square wave. https://www.stereo.net.au/forums/uploads/monthly_2016_12/583f6e91157f6_Class-Dsquarewaveringing..jpg...

But last year or so Stereophile have introduced a special filter (Audio Precision’s AUX-0025 passive low-pass filter) that goes between the the Class-D amp and the test measuring equipment that gets rid of the buzz saw, just for Class-D tests purposes, they always say they use it somewhere slightly hidden in the bench test reports. ( Belcanto with AUX-0025 filter applied https://cdn.head-fi.org/a/1862061_thumb.jpg) Still to me a disgusting looking 10khz square wave, but better than the buzz saw with the special filter.
This is what a proper Linear Class-A/B amp square wave looks like. https://cdn.head-fi.org/a/1862052.jpg


Cheers George

I ran BelCanto with Magnapan 1.6s for years. 

It was pure sex.