Hissing far more in one channel!

[SMEagol]

Firstly Hi All, I've read with interest this forum, and decided it was worth joining - so here I am!

I've bought an old Trilogy VTi integrated amplifier. Its beautifully made and I love the sound yet one thing bugs me , at low volume ther is a noticable hiss, which is very pronounced in the left channel. My speaker is quite close to the amp on that side so I swapped speaker cables round at the back on the channels to see if it was interference. Then the hiss came out of the right. so its definitely something to do with the left channel. This amp uses a pair of E34L and ECC83 valves on each side. It has recently arrived in transit, so I'm wondering if it got drop-kicked from London. I had a look at the walrus forum, and stuck a mains filter on to no avail - any clues? Thanks!

 

[SMEagol]

hiss on the left side ...still...

bump!

sorry but its driving me mad!

 

[Gregm]

Fm yr description it looks like a valve thing. CAREFULLY swap places on the 83s (i.e. switch off, let it all cool off a bit, then move the valves, wait a bit, switch on again, etc). If no change, try the output ones (34)
Good luck

 

[zanash]

yes I agree .....

try gently tapping the ecc83 with a rubber ended pencil ..with low volume and see if one is more microphonic than the other ...

As a matter of course I always fit an identical set of new vales to both channels when I get a second hand valve amp ....you just never know how long they have been used for.

 

[bottleneck]

Hi Smeagol

Welcome to ZG. Hope you enjoy it here.

I'd reccomend getting some new input valves (ECC83's by the sound of it).

If you do this, get the least microphonic ones you can. Watford Valves have a special machine to test microphony. They sell these valves at a slight premium. I think this is what you might be hearing.

Further reductions can be made with special 'O' rings around the valves. Zanash and others (or a forum search) will tell you about DIY ones.

I've never gone this route, careful shopping for less microphonic valves fixed me.

Cheers,
Chris.

NB
Dont forget to put posts in the kit page, it's a good start.

 

[SMEagol]

Thanks!

Greg, Zanash and Bottleneck

Thanks so much for the advice, someone I spoke to thought it was the input stage valves. I spoke to a valve retailer and he said get a quad matched set of ECC83's. He told me to get the lid off and swap the tubes over to see if the problem shifts to the other channel as Greg said ...If its not the input valves, repeat with the E34L's. Zanash your method sounds like a nice quick test, I'll look for a rubber ended pencil rather than a screwdriver!.

Watford seems a great source if the test shows up a dicky one, I've found a lot of valve suppliers out there Bottleneck, prices vary a heck of a lot between brands.

I have used Chelmer Valve company before who were superb. If my memory serves me well they send you a quote from your requirements. I'll stick with JJ's as the original spec, one thing I am doing is switching the input valves to 803s's. I talked to Nick at Voc Rock valves, and he sings the praises about these having larger plates and being particularly suitable for hifi.

The lids coming off - in daylight - this weekend! Thanks all. Chris.

 

[SMEagol]

The advice was bang on.
I swapped all the valves for brand new ones, channel hiss issue has gone, I thought I'd give the new buyer a nice new set of valves into the bargain. It'll need a little breaking in as they are fresh out of the box but its sounding good already. It will be up for grabs on ebay, I'd keep it but I need the money! Ken Kessler loved it and so did I!