Audio Innovations P2

Does anyone know the valve positions V1 through to V8 and what each valve should be on the original Audio Innovations P2. I’m just checking that the positions that they are currently in are correct.

This is how they are currently set -

V1 - ecc82
V2 - ecc82
V3 - ecc83
V4- - ez80
V5 - 5687
V6 - ecc82
V7 - oa2
V8. - oa2

I find the lack of symmetry offensive.


That’s excellent ! So they are all set out ok. Thanks Murray Johnson. :smiley:

It’s a phono stage. You try to keep noisy stuff ie transformers and chokes, far away from low level circuitry.


I’ve changed out all the valves except the 5687 as I can’t find one at the moment and I still get get like a intermittent russle sound like a dodgy valve, if I take out the ez80 completely it disappears anybody got a clue? Before I send it to someone to be checked over.

Bad contact somewhere? - dirty or skinny pins maybe, or worse, bad solder joint.

There are also a couple of little trimmer pots in the power supply near the 5687 which could be showing their (30 year) age.

In my (worthless) experience it’s ALWAYS the fucking valve, even when it measures perfectly and works fine in other people’s amps…

God I hate valves… :poop:

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Can I have yours ?

Oh, hang on …


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Thanks guys, I can do valve swaps and tests on them etc, but I can’t track / trace faults, so I think it is off to guy who can, I’ll give him your wise words on the matter, except for Maureen as he hates valves. :rofl:

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Closer to the truth.


I’ll give the sockets a clean as a last resort. I might get lucky.

On one channel or both?

It you take out the ez80 you have efeectively switched it off, so it will be quiet then

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I think it was both, I’ll have to check again tomorrow, I know it was definitely on the left channel.

Noisy OA2 were the biggest problem i had when using a similar psu design

I’ll do another valve test on these again tomorrow.

I learned from the best mate :ok_hand:

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Anyone have a schematic for a Audio Innovations P2 ? Seems to be very hard to find one anywhere. Noisy on left channel only, sounds like a valve but all valves check out fine. The 5687 valve gets very hot fast compared to the rest, is this normal.

I have a PDF of an article by Peter Willenswaard about modifying the P2, but I can’t upload it to the site.

it includes this:

He prefers it without the 5687 or OA2s in circuit

copy of it here:

he talks more about the shunt psu part in the article about the L2 here:

both on AN UK website btw