Anderton '64 reissue JTM145 - any info?

[Littlewyan]

1. I can't see very well but basically the two wires that go from the 12AU7 to the Output Transformer. Try swapping those.

2. Ah I see now.

3. Actually that could be possible, scrap that idea.

[Matec]

Well

Finally we come to this last item.

There are 5 capacitors in my schema that I could not read the exact values ​​in JTM1.

They are C6, C9, C19, C24 and C201.

The values ​​that are in the scheme have been tested by me. I did tests with them and found that their values ​​were acceptable. But I do not know if they are correct. I expected to come fixes anyone who has seen values. Still awaiting the actual confirmation of these values ​​and some more details to the PCBs - (JCM1).

So all suggestions and mods that are made in the values ​​of the scheme, will be welcome.
And comments about them too.

The RC filter on the plates of the output tubes is simple. And it is very effective.
But the resistor value should not be changed. Small values ​​can cause large swings as well.

The capacitor is less critical. Higher values ​​attenuate even lower frequencies. Small values ​​operate at higher frequencies. The value I used seemed good.

Perhaps for the sake of the speaker, other values ​​can be tested.

Have fun

Matec.

PS. Damn! The value of C202 in the scheme is wrong. He always was 220pF. I must be going crazy!

I'll make a correction and post here later. Sorry!

[Littlewyan]

Well even though you estimated those values Matec the amp still sounded pretty dam good in Smokebreak's clip. So you can't be far off. Either that or you've improved it . Looking at my simulation the amp doesn't have as much bass as a JTM45 should so Smokebreak's clip sounded more like a 1987 50w, but thats not a bad thing

[Matec]

arjepsen

The values ​​of the voltages you measured, are good. Similar to what I'm measuring here. For more accurate they are the valves, there are always large tolerances in the plate voltages.

Littlewyan

It would be nice that I always make amplifiers that were better than the originals. Sometimes they look good.

[arjepsen]

It's still quite bright, but I think I'm starting to live with it now
Another problem I'm working at, is some hum.
It's actually not surprising that I have hum, considering how cramped I made it...
I have two 100R's going from both heater wires to ground. I tried connecting them to the cathode instead of ground, but that only gave some weird sort of oscilation sound when I cranked the amp.
Right now, I've connected them to a 200k going to b+2, and also connected to a 47k and 10µF going to ground, thus elevating the heaters. It helped a bit, but it's still there.
Any suggestions on getting it further down?

[Littlewyan]

Are the heaters wired in phase? So are pins 4/5 on each socket connected together on one wire and pin.....9 I think it is on the other wire?

Also did you try swapping the output transformer wires? As if the NFB isn't working then you'll get issues like this.

[arjepsen]

Yes, the heaters are wired in phase.
Also, I tried changing the ot primaries around. Didn't really change anything.

[Smokebreak]

I would try and figure out why it's oscillating when connected to cathode. 100r from each leg to cathode is the method I always use. It should work just fine

[Littlewyan]

Does the amp hum with the volume on 0?

[arjepsen]

Yes, it does hum with volume on 0, and it also gets louder when turning up the volume - even without a guitar plugged in.

[Littlewyan]

Does it hum if you remove V1?

[arjepsen]

yes, it hums even if I remove the first tube.
Not as much as if I turn up the gain, of course, but the same as if the gain is turned down.

[Littlewyan]

Hmm we could be dealing with more than one source of hum here. What is that resistor you have in series with the heater between the valve socket and tag strip? I cant see where you have two 100R resistors from the heaters to ground.

[arjepsen]

It's a 0,22R resistor, to bring down the heater voltage a bit.
Actually the 100R's aren't connected to ground anymore, I elevated them.
Here's a few updated pics.

[arjepsen]

Oh, and again: How much voltage swing will the 220pf in the tonestack see?
I got a 160V thingie in there, and worrying a bit about whether it's enough.