The Amp Garage

I'll take you up on that Jim!

Somehow me thinks it will be a while before that happens though

Scumback Speakers wrote: ↑Thu Apr 30, 2020 8:38 pm Hey Kurt! We can always stuff your gut with lasagna next time you're in So Cal! I'll get around to that article in the next few days. Thanks for the link!

Jim

Hi Jim

Hope you're well. Been a long time mate!

Try this resource:

https://www.ampbooks.com/mobile/classic ... ldano-slo/

It's great write up for understanding the preamp section of the legendary SLO.

Cheers

Kurt

studiodunn wrote: ↑Thu Jul 18, 2019 5:15 pm Does anyone know what the Raw Bias voltage should be on a MCI 100w? I have rebuilt the bias circuit to 2203 specs and am sitting @ -44v. Does that seem low?

I would just stick the E34Ls and see whether it biases up. I'll check what mine is next time on the bench.

What is your plate voltage?

Good observations!! KDMay, is that a 47nF PI decoupling cap across the second grid resistor and tail resistor? Standard Marshall value would read 100nF, although it should not make a huge difference. Also, on the infamous handdrawn schematic it says the presence cap value is 470nF instead of the "st...

studiodunn wrote: ↑Tue Jun 04, 2019 10:41 pmThanks, I assumed so and just went ahead and used a 2203 layout, but used a 21k pot resistor. All seems well now.

Hey while you have it on the bench, can you please verify that the lead boost function brings in both bypass caps on the 1st and 2nd gain stages?

It would just be a standard Marshall bias circuit

Colossal wrote: ↑Sun May 19, 2019 8:44 pm Excellent! Thanks for updating the board layout.

No worries. Good to have people check it over

Colossal wrote: ↑Sun May 19, 2019 12:36 am Is the PI tail really 4k7?

Good pickup - that should be 10k!! There is a 4k7 to ground, like this.

I personally believe that the OT variations he offers are steel type, not primary impedance changes. But this is personal view. I've already done an MC2 layout, but I had a power supply board with rectifier and switching supply already, so this is the preamp section only. You might find it useful. I...

Regarding the bright controls; if you wired them up, did you find them useful? If they are fairly effective, it could make the amp a lot more usable with singlecoil guitars I reckon. The bright controls I find very useful (I only have the lead channel connected). I ended up actually putting in a br...

[quote="chief mushroom cloud" post_id=397727 time=1556724621 user_id=54] [quote=kdmay post_id=397613 time=1556499639 user_id=9465] Quick question: can 2 of these chips be used simultaneously for 8 channels? Wondering how the flip/flop reset would work in this instance [/quote] Yes. We used this circ...

Great project!

I’ve had some of these made and in the next few weeks will incorporate into a 4 channel amp, so will report back.

Quick question: can 2 of these chips be used simultaneously for 8 channels? Wondering how the flip/flop reset would work in this instance

Cheers

He just uses the standard SBE715P Orange Drops. No Mallory PVC mojo here! LOL The Lead channel differences from the MC1 to the MC2 AFAIK are the bright control only. That's the difference between the hand written and computer drawn one. The Rhythm channel are very different in both amps. MC1 is 2 st...

People only describe them as Hiwatt Marshall hybrids because of the feel. They are very big and open sounding amps, which I guess is like a Hiwatt in some ways. But it really shares nothing with a Hiwatt, as Roe says. It achieves this sound from a huge plate voltage (520vdc on the plates) and the pl...

I should also add that the MC and MC2 apparently bypasses both the 1st and 2nd stages for their boost. I have tried this in the past and didn’t like the unboosted mode and found the 1st stage bypassed permanently with he 2nd stage bypass as the boost a better option. Hence we drew it that way