[BillinSF]

AHB2 has probably one of the most comprehensive protection setups available so if that was the amp being used it's unlikely the amp.
Still, odd to have the same channel die twice.

Yes GS, some red lights came on the front panel of AHB2. It was weird, because I turned the unit off and the lights did not go off. I think some protections kicked in. But too late for one channel I guess.

Will inform the group as to what Benchmark says. I suspect they'll have a bit of concern. I think HP world is a big part of their marketing channel.

 

[GoldenSound]

Yes GS, some red lights came on the front panel of AHB2. It was weird, because I turned the unit off and the lights did not go off. I think some protections kicked in. But too late for one channel I guess.

Will inform the group as to what Benchmark says. I suspect they'll have a bit of concern. I think HP world is a big part of their marketing channel.

Which lights came on?

The lights give a fair bit of info as to what is causing the fault

 

[Polygonhell]

If there are any tubes in his chain, I'm assuming he's using the WA22 as a preamp, which would bypass the transformer, AFAIK. If the Benchmark amp is DC-coupled, it could still be an issue. The Benchmark could also be generating DC offset. Measuring would be a good first step.

The only step that matters for DC offset is the last one.
Transformer coupled tube amps remove it with the output transformer.
SS amps have 4 possibilities, use an output transformer Ala Macintosh (very rare), use a big capacitor, use a DC servo (which can be poorly done) or very carefully set the output bias to null it out, the latter usually involves trim pots being set at the factory because of variance in individual parts.
The issue with using speaker outs is they don’t have to be as careful with DC offsets, in fact some down facing subwoofers have amps that intentionally run with a small ammount to offset the driver sag caused by gravity.

 

[BillinSF]

Which lights came on?

The lights give a fair bit of info as to what is causing the fault

Gee. I wish I'd taken a photo. I think it was the clip and mute lights on both channels.

 

[Sand Dan Glokta]

@BillinSF

If you have a multimeter, you should measure the DC offset across each pair of speaker terminals on your power amp. That's probably the biggest potential issue when using a speaker amp. OTOH, you may also just have a faulty connector or connection, as opposed to a damaged driver.

Hifiman made me messure the cable pins conected to the amp, before replacing the dead driver.

 

[BillinSF]

I know this is not hi-tech. But.

When I was in college 45 years ago, I had an audiophile setup. Advent speakers. Not the most expensive, but very quality. I had a nice amp.

They could handle a lot of power, but..not noisy power. I jammed with loud music all the time.

Then I loaned them to a friend for a party. Was nervous. He had a cheap amp. Blew both speakers. Noisy power..Grr.

 

[BassicScience]

I know this is not hi-tech. But.

When I was in college 45 years ago, I had an audiophile setup. Advent speakers. Not the most expensive, but very quality. I had a nice amp.

They could handle a lot of power, but..not noisy power. I jammed with loud music all the time.

Then I loaned them to a friend for a party. Was nervous. He had a cheap amp. Blew both speakers. Noisy power..Grr.

Your friend's amp might simply have been underpowered, hence clipping. Noise generally doesn't damage drivers.

 

[Sand Dan Glokta]

Your friend's amp might simply have been underpowered, hence clipping. Noise generally doesn't damage drivers.

A question. I had clipping with a90 susvaras.
I even had with aryas (very loud of course). I thought clipping was because the amp. But a friend says its the hp. Who is right?

 

[BillinSF]

Had a nice chat with Rory at Benchmark re my issue. He's concerned and forwarded this thread to his tech people.

"Yes, of course, less than pristine input into AHB2 could cause problems."

I told him that the fate of his company selling AHB2 to Susvara fans depended on his response. :O

I'll let you know anything more or they'll jump in with input.

 

[GoldenSound]

Had a nice chat with Rory at Benchmark re my issue. He's concerned and forwarded this thread to his tech people.

"Yes, of course, less than pristine input into AHB2 could cause problems."

I told him that the fate of his company selling AHB2 to Susvara fans depended on his response. :O

I'll let you know anything more or they'll jump in with input.

It could be something from the WA22.
iirc the WA22 preamp outputs use a resistor circuit not a transformer and so could pass DC etc

 

[BillinSF]

It could be something from the WA22.
iirc the WA22 preamp outputs use a resistor circuit not a transformer and so could pass DC etc

Yup. Gave him the whole story.

 

[GoldenSound]

Yup. Gave him the whole story.

One thing to check, when you were using the WA22 as a pre, what vol did you have it set to? (And what gain setting do you have the AHB2 on?)

 

[BillinSF]

One thing to check, when you were using the WA22 as a pre, what vol did you have it set to? (And what gain setting do you have the AHB2 on?)

Medium vol on WA22 (hi Noon) low setting on impedance output.. Mid gain level on AHB2.

 

[theveterans]

I am wondering about tubes also giving some kind of deviation(as tubes wears out) in DC offset...in long run can fry headphones. Just a thought. I always measure amp for this.

As already discussed, SET amp should take care of the DC offset. Not sure if a DC input to a SET amp can fry the Susvara

 

[theveterans]

A question. I had clipping with a90 susvaras.
I even had with aryas (very loud of course). I thought clipping was because the amp. But a friend says its the hp. Who is right?

If the Arya clips, it's the amp IMHO. Using 45 or 2A3 or pentodes that are triode strapped on a SET configuration can potentially clip a Susvara on very high SPL though