JM Signature Build

[dreric]

Hi Guys

I'm been lurking for too long, I got distracted by guitar making due to a Les Paul junior obsession. Now it's time to get back to amps.

I have all the parts for a JM Signature build. I've been searching through the files and it seem the layout, with SSS name, has some errors and there are several version of Aaron's schematic.

It there a definitive thread on this amp?

Thanks
Eric

[dorrisant]

I think this is the one I used...

[M Fowler]

That's the schematic I used and I did not make any component changes either.

Sold the amp and the owner is very happy with it so we know that schematic will produce a good product, have fun.

Mark

[dreric]

Thanks guys!

[telentubes]

I have all the parts for a 4 X 6L6. Just need to find the time.
Are you planning a 50 Watt or 100 Watt? It will be great to follow your build once it gets rolling.

[dreric]

I'm planning a 4-6V6 version. I'll post pictures as I go.

[Aaron]

Just noticed that I've drawn the speaker outputs wrong.
Obviously the tip doesn't go to earth. Should be parralleled to the ext speaker tip and then to output transformer.
Aaron

[dorrisant]

Just noticed that I've drawn the speaker outputs wrong.
Obviously the tip doesn't go to earth. Should be parralleled to the ext speaker tip and then to output transformer.
Aaron

We should all be smart enough to disregard that one little misplaced dot...

Great drawing... I wonder how many have been built from it.

[dreric]

I'm trying to understand the power supply on the schematic post above. There is an additional secondary that I don't understand and there's a toggle weird thing and two bias pots? Is there something that I'm not understanding?

This older schematic has a PS that I understand and one that seems to match photo's on other builds and the layout.

I must say that I have a love hate relationship to the layout. I appreciate the work that went into it and the sharing. Conceptually it's good but there seems to be a lot of errors and significant omissions.

[dreric]

Here's a few pictures of the PT wiring and the filter board. I'm planning on 4-6V6 so the first stage are 100uf rather than 220uf.

Power Transformer is a MC 40-18005

[Aaron]

I'm trying to understand the power supply on the schematic post above. There is an additional secondary that I don't understand and there's a toggle weird thing and two bias pots? Is there something that I'm not understanding?

This older schematic has a PS that I understand and one that seems to match photo's on other builds and the layout.

The prototype has the hi and low power switch. When switching to the low power the bias would need adjusting, hence the second bias pot.
So switching the hi-low also switches the bias.
Thanks,
Aaron

[martin manning]

The prototype has the hi and low power switch. When switching to the low power the bias would need adjusting, hence the second bias pot. So switching the hi-low also switches the bias.

Aaron, what power transformer did you use, and how much difference is there in B+ in the low power mode? Did you end up staying with that configuration?

[M Fowler]

I went through all the posted schematics and found slight errors which were all addressed in the original post.

The schematics PS are the same.

[Aaron]

Aaron, what power transformer did you use, and how much difference is there in B+ in the low power mode? Did you end up staying with that configuration?

I haven't built it with the dual windings. Only with a standard twin transformer. When I traced it at the time I couldn't find other info on voltages. Hopefully someone who access to the Two Rock dual supply will chime in.

Thanks,
Aaron

[martin manning]

Thanks, Aaron. I think it might more likely be something like this.