valve problem?

[philv]

I have a jolida fx2 dac.

Just bought some raytheon 5575 valves off these forums and adaptors off ebay.

Used for first time today.

1) Left channel - has bad hum increasing with volume.
Right channel - sounds good.

I swap over the valves (not the adapters).

2) Left channel - sounds good.
Right channel - no sound at all from speaker.

I swap valves back and forth.
Each time i swap, it goes 1) 2) 1) 2).....etc (above)

There seems to be one good valve.

The other valve seems to have problems as when in one channel it hums, and when in the other channel it looses sound altogether.

I have repeated this 6 times.

Valve problem?

Or am i missing something?

Thank you.

[Ali Tait]

No, send em back.

[philv]

The seller on aos was very nice and refunded.

I'll revisit the 5575 when the world is the right way up again.

Thanks for the replies.

[Ali Tait]

It’s rare but it does happen. NOS will always be a punt. Small valves are usually reliable though, can’t recall one ever letting me down.

[philv]

What baffled me was the act that the bad one would hum in one converter and not work at all in the other.

Would love to know why.

[Blackdog]

Do you mean 5751 tubes? 5575 is not a compatible tube.
As to why one spot hums and the other is dead, is that the two triodes inside each are used opposite each other in each channel.

[philv]

Do you mean 5751 tubes? 5575 is not a compatible tube.
As to why one spot hums and the other is dead, is that the two triodes inside each are used opposite each other in each channel.

5755
Would like to know why the differing behaviour.

[Blackdog]

As i said before, these tubes are dual triodes. The two triodes are used differently. They are probably reversed in purpose between the channels.
Your dac uses 12ax7 tubes does it not?
The 5755 is not compatible. You may actually damage the tube or your dac using them.

[enrae8]

I have a Glass FX DAC - I ran it for quite some time with 5755 valves no problem at all

I used Harma Cryo for a long time really enjoyed them
I now use Brimar 12AX7 Long black plate square getters (I didn't realise I had them stuffed in a box) very nice:)

[Blackdog]

Are you using a socket convertor?

[philv]

Are you using a socket convertor?

Yes.

OK....i understand now about the dual triode part.
Thanks.

[enrae8]

I used a socket converter - they are highly recommended valves for the Glass FX - the Jolida importer at the time Highly recommended them - perhaps he'll comment here if he comes across the thread - or perhaps PM him -OpenDoor on here Robert is a great guy to deal with

[enrae8]

Ignore me - I think I've got the wrong end of the thread:eyebrows:

[Blackdog]

Yes.

OK....i understand now about the dual triode part.
Thanks.

Now I get it. They should have worked. Just bad tubes.

[Open Door]

A suggestion to try :)

Usually NOS 12AX7 type tubes have thicker pins than new issues. The 5755 adaptors have quite thin pins in comparison. So if they are replacing NOS tubes, there could be bad contact. Try move/shift the 5755 tubes (in their adaptors) gently when in the dac to see if that makes better contact and eliminates the problem.

5755’s are usually extremely reliable.

[Lawrence001]

A suggestion to try :)

Usually NOS 12AX7 type tubes have thicker pins than new issues. The 5755 adaptors have quite thin pins in comparison. So if they are replacing NOS tubes, there could be bad contact. Try move/shift the 5755 tubes (in their adaptors) gently when in the dac to see if that makes better contact and eliminates the problem.

5755’s are usually extremely reliable.I had a problem with a valve socket years ago, I thought it was a faulty valve crackling but another one has the same problem and it was worse when I wiggled it. I used a pin to force the metal grips tighter in the sockets and the valve was good after that.