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All Mullard or GEC, I'll check at the weekend to see what I've got, I didn't have time to research them all. There were only two 12AX7's and one EF86, the rest I didn't recognise and had odd designations.
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
Pinouts are totally different but the electrical characteristics look virtually identical to the ECC83/12AX7? I would use a B9A plug and valveholder and make an adaptor, hold the valve in a tool clip.
Dave.
http://www.ebay.co.uk/itm/1pc-Gold-12AX7-TO-6EU7-tube-converter-adapter-Brass-metal-case-/191812104990?tfrom=201123876948&tpos=top&ttype=price&talgo=undefined
Well! Who would have thought it! ^
Dave.
Not trying to be funny!
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
To be honest I don't think valves have ever been cheaper than they are now, in real terms. You can get a perfectly decent 12AX7 for under a tenner, which is actually less in plain numbers than they were 20 years ago, let alone accounting for inflation.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
There's good deals to be had on old tubes on ebay if you look around
Cheap, yes. I recall testing valves for customers because they were costly. They brought them in out of their radio or (worse!) telly and I had the job of running the Avo tester. I got so I remembered the numbers for the Paxolin cards for all the common types, EF80, ECL80,ECH33,6V6 etc. Cost them sixpence a pop (2.5p) but that was waived if they bought a new valve.
Of course! When they got home they would invariably fit them back in the wrong positions (despite there almost always be a diagram in the radio/tv . Don't get THOSE these days!) blow the bugger up and come back with it next day!
Jeeez! The STUFF I could/should have salted away!!
Dave.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Before you do that, you can short the valves control grid to ground to see where the noise if being injected.
Did you try changing the V1 grid stoppers (68k?) I had similar problems with an amp very hissy, changed all the usual suspects. Didn't think that those resistors would have an impact, read that they can and reducing the value can help, changed them to 20k .... no more hiss (well, very little) and still no RF with that value.
All resistors generate Johnson noise. The higher their value the more noise they produce.
Reducing grid stopper will reduce noise.
If RF breakthrough is a problem then a small cap can be put on the input.
You can easily identify the contribution of noise from the grid stoppers by shorting the control grid to ground an listening to how much the noise goes down.
Yes.
They should be on the valve pins.
Part of the reason for adding the grid stops is to isolate the input capacitance of the valves from the lead inductance.
The combined lead inductance and input capacitance can form a resonant circuit that can pick up RF.
Here's a practical example of the effect of placement of grid stoppers:
http://jpfamps.com/fender-tonemaster-tone-master-guitar-amp-repair/