From Scratch Amp Building Chronicle - 6/13/10 UPDATED!!

[scottosan]

Steve,

Looking at the wire coming off of the left most lugs of the lars/mars MV, I don't see any connection to the -DC bias voltage from lugs. You have the blue lead of the multi conductor cable terminating at the juction of the 82k/100k resistors, which is incorrect. I needs to go to the -DC Voltage at the juction of the 15k/47k juction. looking at a typical marhsall layout the turret at the junction of the 220k bias splitters has a lead connect to -DV bias voltage, it woult terminate there.

 

[Anonymous]

Steve,

Looking at the wire coming off of the left most lugs of the lars/mars MV, I don't see any connection to the -DC bias voltage from lugs. You have the blue lead of the multi conductor cable terminating at the juction of the 82k/100k resistors, which is incorrect. I needs to go to the -DC Voltage at the juction of the 15k/47k juction. looking at a typical marhsall layout the turret at the junction of the 220k bias splitters has a lead connect to -DV bias voltage, it woult terminate there.

Correct! I misread my old Marshall layout. As I said, I still need to go through a bunch of stuff, but good catch!

Steve

 

[Anonymous]

waitaminute..
no external bias adjustment/points....



just kidding...looks marvy

This has already been requested as a future feature, however, I can't imagine where I'd fit it!

Steve

 

[Anonymous]

Fixed the PPIMV problem. I've gotta go back and fix my schematics too - there are several errors...:

Steve

 

[MARK1970]

Nice Steve, I can't wait for the finished product.

 

[Anonymous]

Nice Steve, I can't wait for the finished product.

Thanks man! making some good progress... Is that Alexis Texas in your avatar?

Steve

 

[Anonymous]

Made some more progress here. Wired up the PT, Mains, Standby, filter caps, etc. You can see where I'm showing wires going under the board because they change color when they hit it. Not perfect, but looks pretty good. There may be some mistakes as I didn't double check everything, so bonus to anyone who points 'em out. Now on to the front panel controls, cap under the board and the midi din for the footswitch. Then I'll do the extra board and 6V AC PT for the relay power... Once that is done - double check everything, clean up wires a bit, fix the mistakes on my schem and get on with the build... Anyway... here is the latest:

Steve

 

[mentoneman]

does it have a letekro channel?

 

[Anonymous]

does it have a letekro channel?

You have to purchase the optional flanger mod...

Steve

 

[tweed]

Steve, how's this amp coming along my friend. NAMM is almost here. : )

 

[Anonymous]

Steve, how's this amp coming along my friend. NAMM is almost here. : )

How's the amp coming along? C'mon man, follow along here - I just posted where I am...

Steve

 

[tweed]

Steve, how's this amp coming along my friend. NAMM is almost here. : )

How's the amp coming along? C'mon man, follow along here - I just posted where I am...

Steve

Hehe

I tried to follow along with the pretty pic, but I just don't get it yet Hopefully one of these days the light bulb will go off.

 

[ratter]

Is it too late to request external bias points and pot?

 

[Anonymous]

Is it too late to request external bias points and pot?

It's a good idea and several have brought this up, but with my layout I really do not have any space left for bias points and another pot... I'd have to move away from the concept of keeping this is a Super Lead style head case...

Steve

 

[Anonymous]

Steve, how's this amp coming along my friend. NAMM is almost here. : )

How's the amp coming along? C'mon man, follow along here - I just posted where I am...

Steve

Hehe

I tried to follow along with the pretty pic, but I just don't get it yet Hopefully one of these days the light bulb will go off.

Download the schematics and follow them along with the layout I've posted. You'll figure it out easily if you just look at how the schematic translates to the layout. The power section is basically the same as a '69 Super Lead.

Steve

 

[jerrydyer]

whats that sweet looking heater mod? anti Hum thing? all looks pretty awesome how much of the board is done

 

[Anonymous]

whats that sweet looking heater mod? anti Hum thing? all looks pretty awesome how much of the board is done

Thanks Jerry - that is a DC heater mod for the preamp tubes to reduce hum as you say... I learned about it from Olaf, who posts here and also at metro sometimes...

Steve

 

[Bob Savage]

Is it too late to request external bias points and pot?

It's fair to ask about the external bias point, but pot too? That's illegal, you know.

 

[tweed]

Is it too late to request external bias points and pot?

It's fair to ask about the external bias point, but pot too? That's illegal, you know.

Not if you got a prescription man.

 

[Bob Savage]

Not if you got a prescription man.

To my knowledge, Steve is not a pharmacist, though he does play one on T.V.