Bassman 70 ODS

[guitardude57]

Amp porn.......... Bassman 70 into ODS

Formica preamp board
No relays yet.
Moved OD trim to where footswitch jack was going to go. Have MIDI jack to use for Footswitch........ah, another hole to drill................

Front cab board needs to be resized and recovered with grillcloth. A fan will be installed on this board inside.

Been a fun project!

Marshall 1966A cab is loaded with 2 EVM 12L's

[guitardude57]

More.........................

[guitardude57]

with speaker cab.................

[David Root]

Lookin' gooood! Is it set up to do 70W with one pair? Of what tubes?

I have a NOS Bassman 70 PT which I think could do 100W as a guitar amp PT. Maybe with KT88s.

[guitardude57]

I have Sovtek 6L6wxt's in there............way loud. 508 Volts on the plates.

You will have no probs getting same voltage......SS recto.

[guitardude57]

I guess I need to get the "Dales" in there. Not easily found around Indianoplace.........lol

The clean has almost zero hiss...... the OD has too much. Gain structure definitely at play here.

Maybe shorten the grid leads too. Other than hiss issues, this amp is breaking in very nicely.

Comments and such welcome.
Mike

[Structo]

Mouser carries the Vishay/Dale RN65 resistors.
They are listed as .5 or .6 watt but since they are mil spec they are the same as a 1 watt.

[guitardude57]

Yeah..... I was a goober

We found out why real quiet resistors are used here.........

There are 2 local sources left to check with, after the holiday.

If no gots, we will order from Mouser. Already have an order saved to hit if need be...... Cool to be able to save parts lists under Project names on their site.

Funny, the difference between a 20 cent part, and a 31 cent part.

[Bob-I]

I guess I need to get the "Dales" in there.

Actually HAD didn't use Dales in the high plate amps. I'd grab whatever high quality metal films are available.

[guitardude57]

I replaced the Sovteks with 40 year old RCA 6L6gc's. One of the Sov's didn't like the high plate voltage and shorted out.

Also moved the grid wires around V1 and V2 and lost the hiss/noise. It is quiet now. So, no need to change the preamp plate resistors.

The amp sounds much better now with the RCA's. The OD is more smooth now.

[Structo]

Are you sure you mean the grid wires?

Those are the pins that the resistors are on.

Did you move the cathode wires around?

[guitardude57]

Sorry.....plate and cath moved a little. Grids would be hard to move.....lol
There was interaction happening....hiss.
Just moved a couple wires a 1/4 inch or so......that's all