Listener fatigue

[gilesw]

Well an interesting weekend. Went up to London to demo some rega rs7's with my amp and dac with me. Definitely didn't solve my treble problems but nice wide soundstage with those side mounted bass drivers. He had a naim class a amp though so we tried that out and the treble didn't sound harsh so it's definitely the class d amp that is the issue and not the dac, but I kinda already knew that.

He also had some proac d28's which had a totally different sound, even with the class d amp in there the treble sounded fine, at least for the short time I listened to them. So I'm going to have a listen to some d18's to see if they fit the bill. Despite the problems of the top end fatigue I seem to be addicted to the sound of this amp, to my ears it sounded better than the naim. Next week it's resistor time!

[Reid Malenfant]

He had a naim class a amp though so we tried that out and the treble didn't sound harsh so it's definitely the class d amp that is the issue and not the dac

Naim have never built a class A amplifier, so if someone told you that there Naim amp is class A, then they are talking out of the sphincter

While they may well be AB as I believe Mark mentioned earlier, only about 0.1W per channel (or less) is in class A (frankly I haven't often seen many amps with heatsinking quite that small for the power output - maybe 0.1W is being overly generous ). The rest is in class B, though this should be noticeably superior to just about any class D amp in the extreme treble regions.

What you are probably finding is that the lumpiness of the extreme treble which is caused by the reconstruction filter on the output of the class D amp is exciting the breakup modes of the tweeters on your MA speakers.

Far better to use a soft dome with a class D amp than a hard dome, unless it doesn't go into breakup far above the audio band like a Beryllium tweeter would.

[gilesw]

Heya Mark this more my misunderstanding, I just thought all standard hi-fi amps were class a.. Looks like the proacs use a silk dome tweeter. Did like the sound but then again they were 4k's worth of speaker.

[Reid Malenfant]

Hi Giles, no worries... Just look at the size of the heatsinking...

A real 20W class A amp will have a bigger heatsink than a 200W class AB

In fact a 20W class A amp will look like a humungous amount of aluminium fins, no matter which way you look at it...

I'd expect about 4Kg of aluminium heatsinking, which isn't small

[gilesw]

I have some dali zensor 1's in my kitchen so i'll try them out downstairs as they have the same type of tweeter as their floorstanders and they seem to play nicely with my other chip amp.

[The Grand Wazoo]

A real 20W class A amp will have a bigger heatsink than a 200W class AB. In fact a 20W class A amp will look like a humungous amount of aluminium fins.......expect about 4Kg of aluminium heatsinking.....

25 watts of Class A Mark Levinson (and well known for overheating!):

[gilesw]

jeepers that is a beast! I hooked up a free spectral analyser and tried some pink noise last night, wasn't totally flat, 6-7hertz were louder.

[Martinh]

I hooked up a free spectral analyser and tried some pink noise last night, wasn't totally flat, 6-7hertz were louder.

I guess that you mean 6-7 kHz - can you apply EQ to that area to flatten it out and then listen to the results?

I may be wrong (I usually am) but the forward balance may not just be due to the extreme treble. Also, isn't your speaker a 3way? You may be able to reduce the level of the tweeter AND the next one down to address the balance without major surgery.

[icehockeyboy]

I use a class D Lyngdorf semi digital integrated, before that the power amp only version of it, never had any treble problems at all.

[gilesw]

Interesting, you using the Quad 22 L2 listed in your profile? They have fabric tweeters. I'm going to have a chat to some of the people on the US forum that have the same amp I'm using and see what they are running with it..