Are microphonic valves always bad? PSVane Treasures 6SN7’s

[lilmountain]

Hi all,

In relation to my Cayin CS-150a I’ve had a run of bad luck with 6SN7’s. I’ve tried to buy a matched pair of PSVane Treasures twice now from a UK supplier and right now a Chinese supplier. The first pair one was microphonic, the second pair both are. Now when I’m playing music they sound amazing, not that I have the most sophisticated ears but when I don’t play music and tap them the clearly ring through the speakers.

They’re plugged into the input stage with a pair of Sophia Electrics in the output stage. The latter do not come through the speakers when tapped.

So the question is, am I right in saying they’re microphonic and if so is it always bad? They’re not cheap at £150 a pair new so should I return them in principle?

Thanks in advance for any responses.

 

[THOMO]

The cheap Russian 6SN8s [6SN7 equivalent] black base are microphonic but sound really good.

 

[Lawrence001]

Do you need to tap them though? I usually just tap my foot. Also you'll burn your fingers.

 

[pmcuk]

Microphonic valves can sound wonderful. Many of the old DHTs were microphonic, especially those with low current filament supplies.

 

[lostwin]

The cheap Russian 6SN8s [6SN7 equivalent] black base are microphonic but sound really good.

I've tried these, but don't rate them for SQ with the implementation in my amp. To be fair, maybe I didn't give them enough time to burn in - I pulled them out after a couple of days as they were pretty underwhelming. Red base Sylvania GTA's are my preferred choice.

 

[garn63]

If you like the sound of anything, I would leave it in.

 

[audio_PHIL_e]

I've been told that if a valve goes microphonic you can still use it as a phase inverter.

 

[Jules_S]

You could try some of those damper rings to see if it helps?

 

[Burdy]

I suspect a lot of valves will transmit the sound of a direct tap. It's only a problem if you can hear anything like that under normal listening conditions. A test I heard about was to lightly tap the amp casing or chassis. If you don't hear anything caused by that, you are fine.

 

[pmcuk]

If you want good 6SN7s look for the NOS ones with angled plates/anodes. They always sounded the best to me. Anodes are at 45 degrees to each other. Any make is good.

 

[Jazid]

If you tap small signal valves, and there is a 'tink' from the speakers than that is more or less normal. If its a 'tiiiinnnng' then that's personal preference: if they sound good they stay kinda territory.

If you tap them hard and there's a 'buzz, crack, bang' noise then that's not so good.

 

[bencat]

Given my usual heavy handed clumsiness if I tap them they go crack and break they never sound that good after this .

 

[lilmountain]

Thank you all, this is really helpful. As a complete beginner to valves it's useful to get all of this together, can be a bit of a nightmare trying to research all of this alone! I'll do some serious listening tonight, try the tap the amp test and make my decision from there. I suspected some of the advice would be around trusting my own taste and ears but wanted to make sure being microphonic wasn't a sign of a faulty valve that would deteriorate quickly. If it's simply a matter of how it sounds then that makes it all a lot simpler.

Thanks!

 

[Lawrence001]

Some valves are more microphonic than others. Eg I have read (but it may not be true) that long plate ECC83s are more so than the short plate versions, and the latter are better in high gain phono stages but that could just be BS.

 

[Psilonaught]

Hands down best 6SN7 is the Linlai Global Elite E-6SN7.

Seek out comments on various forums.

I have a pair and they work flawlessly. They also benefit from having a warranty as they are not NOS.

 

[Jazid]

Hands down best 6SN7 is the Linlai Global Elite E-6SN7.

Seek out comments on various forums.

I have a pair and they work flawlessly. They also benefit from having a warranty as they are not NOS.

Or, for less money, you could get a NOS pair of 5692. They were developed as low noise, low microphonics, for professional use. Still a fair few around. Just sayin..

 

[lostwin]

Or, for less money, you could get a NOS pair of 5692. They were developed as low noise, low microphonics, for professional use. Still a fair few around. Just sayin..

Look to be at least £100 each though, unless you can point me in the right direction.

 

[Psilonaught]

I've tried various nos 6SN7 tubes and I always seem to find new ones superior sounding.

Are NOS tubes really better than the very best new...

I tried various old globe DHT tubes for example but the modern EML 45 beat them all.

NOS is overrated although the rolling part is fun I admit.

Or, for less money, you could get a NOS pair of 5692. They were developed as low noise, low microphonics, for professional use. Still a fair few around. Just sayin..

 

[Nagraboy]

My Croft pre has started ringing via the speakers when I tap the chassis, flip the switches or tap the interconnects attached to it. Just received a new pair of RCA 12BH7A valves and will see if they solve it.

 

[Jazid]

I've tried various nos 6SN7 tubes and I always seem to find new ones superior sounding.

Are NOS tubes really better than the very best new...

I tried various old globe DHT tubes for example but the modern EML 45 beat them all.

NOS is overrated although the rolling part is fun I admit.

I haven't tried the CV181 if that was what you refer to, but then it's an ECC32, not a 6SN7, at least the original was.

Yes, I agree that new tubes can sound great, loads better than some of the half-knackered reject stock that gets peddled on the 'bay and such. And a cheap manufacturer's old stock valves mightn't be a match for a' 'price no object' premium modern design. But modern manufacturers can't compete with the quality of old stick simply because of the scales involved. Modern metallurgy and the vacuum forming process are not as good because the market volume simply doesn't support the production of such expensive components and machines. As a result, typically, a new production valve won't last near as long as its NOS equivalents.

So saying, EML make very robust valves that are often tweaked versions of the originals. They inspire confidence. I haven't heard the 45 but had some 300b which looked the part but sadly were trumped sonically by other makes, in my amp at least.

I suggest that a modern manufacturer can and does tweak the curves of their products to deliver, for example, a slightly higher gain or transconductance or power output, and as a result the valve may sound better in an amp. In the past manufacturers had to be compliant to datasheet performance because the valves might be put to use in very different situations than just audio. This is not an issue now, they simply won't be.

So no, NOS is not overrated at all. But if you prefer modern then excellent, fill yer boots!