Metropoulos Forum

With all of the interest in earlier 100 watts lately, I thought a diagram might help. This is the circuit and layout in my '67.


George

Here's a smaller copy of the jpg.

George

Is that 68k in parallel with the 10uf normal?

Thank You for the layout George.
Thats gonna help me bigtime.

Pat

thats for biasing correct?
stan

I though the mix resistors were 270K in 67?

The 68k is for biasing.

My late '67 has 470k mix resistors, but they should be 270k earlier in '67.

George

Thanks George.

5150loveeddie wrote:I though the mix resistors were 270K in 67?

Those were in the JTM's
Ralle

George,

You sure you don't have a 10k/1watt resistor in series with that 8k2/1watt resistor on the H.T. line? I know the earlier '67 amps had just the one 8k2 resistor, but I thought your amp was a slighly later '67 amp.

Ralle 500 wrote:

5150loveeddie wrote:I though the mix resistors were 270K in 67?

Those were in the JTM's
Ralle

Yeah?

I read an article somewhere specifically about those mixer resistors. It said you can date marshalls by the presence of 470k mixers because they started in early 67. If the amp has 270k that doesnt mean its pre 67 because they still showed up in amps after the 470k's but the 470k's started being used at a specific ttime.

I remember that too but I don't remember where I read it.

What would be the differences between the 270ks and the 470ks? Anyone knows, more gain with the 270Ks mix resistors??

no. More high end less gain. 270k has less resistance between the mixer and the unused/opposite channels volume pot ground. In other words the volume controls are more interactive with each other.