SET Distortion at higher volumes?

@dhcod 

Is this the same issue that prompted your other thread regarding 20 watt or higher amplifier options?

Charles

Not idea really. Swapped in a new arm and it went away. I'm just glad it went away.

@dhcod 

Very pleased to hear your issue is solved.

But I am very intrigued by tonearm originated distortion that presents at high volume but not at low volume.  Can you elaborate please?

We can tolerate lots of even order tube generated harmonic distortion before sound becomes obviously distorted. Lots of digital pop and rock recordings are mastered using tube compressors or other tube signal processors that generat harmonic distortion in to make them sound fatter and more "analogue".

The problem was traced to the tonearm. The amplifier is not the culprit.

Charles

Tube dampers dull the sound for me.

Spatial Audio Labs make a very nice open baffle that's very efficient 

and has powered Bass . Which work great with SET amps.

using the excellent Beyma midrange tweeter amp driver + Bass .

Depending on what you have many lower priced  amps have sheet metal cases that ring ,vs say a Ayon  brand which is machined aluminum .

your tubes need dampers Herbies tube dampers on All tubes especially power tubes vibrate and ring , if you tap your chassis and can hear it through your speakers you have bad microphonic issues start with the tube dampers. 

SET amps are most linear when they are operated at 25% of their rated power: ie 2 watts for an 8 watt 300B. Distortion rises rapidly after that. I have three: a 45, a 2A3 and a 6BG6. They await a suitable speaker after I sold my Heresy's.

@dhcod glad to hear your found a problem and it wasn't a head scratcher.  your amp distorting with 96dB speakers would have been, assuming non-concert volumes.

Always wanted to try an SET amp/amps.

@dhcod

Problem solved. Tonearm issue. Thanks, these responses directed me elsewhere.

I am happy that you sorted it out. As with other posters here I was skeptical about assuming it’s the SET amplifier at the heart of the issue. I use an 8 watt SET amplifier paired with 94 db (14 ohm) speakers. The sonic strengths of this are the purity, naturalness and ease. Yet at the same time very lively, engaging with good dynamic contrast.

Charles

Problem solved. Tonearm issue. Thanks, these responses directed me elsewhere.

It would help to know a lot more specific details, like the amp in question, the speakers, how large the room, how loud you are trying to play the system, whether you tested the system with a different amp, etc.  Just knowing that a speaker is rated as 96 db/w does not give enough detail on how suitable is the speaker for SET use.  For example, the Wilson WP 6 had a quite high efficiency rating but it was very difficult to drive and was not suitable with many amps, particularly low and medium-powered tube amps.  Is this a problem in both channels playing a mono source?  Do you have a way to test the tubes or swap in a different set of tubes?

Severe distortion from being pushed to hard could indeed sound like mis-tracking.  But, long before you get to that point you should be able to hear the onset of such problems.  First, SET amps will start to compress—the music will stop getting louder even as the volume is turned up.  The sound will also become a bit muddled and lacking in clarity.

Good luck on solving this problem.

I'm using a 300b and it is almost always using a watt or less with most material.  

I’m playing with a 1.8 watt 45 SET with my 96 dB rated speakers and I can’t turn it up high enough to distort. Amps vary, speaker ratings vary. What tube are you running and what speakers?

The OP can change to Klipsch Khorns (104db sensitivity) but then he will have to suffer with their infamous sound colorations.

How much power is the amp? I run Lamm ML2- 18 watts each, but speakers are nominally 104db at 1 meter. Never have a problem, I don’t listen at jet take off levels but call it 80db with some higher peaks, C weighted. Could also be other things- mistracking if a phono is involved for example.