Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: chris s on March 30, 2023, 07:00:13 pm

Title: Small amp suggestion using Peavey Classic 50 parts
Post by: chris s on March 30, 2023, 07:00:13 pm
Hey all I’m looking to build a smaller amp using parts from a peavey classic 50.

Just looking for suggestions where I could use peavey classic power transformer…

Primary:      
      240V            White
      230V            Grey
      0V            Black
 
Secondary:
      320V@250mA      Red
      0V            Red
 
      6,3V@4A            Yellow
      0V            Yellow
 
      22V@300mA      Orange
      0V            Green/Yellow
      22V            Orange

And output transformer…

Primary                  
      A1            BLUE
      B+            RED
      A2            BROWN
                  
Secondary                  
      0 Ohm            BLACK
      8 Ohm            WHITE
      16 Ohm            ORANGE
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: tubeswell on March 30, 2023, 07:33:48 pm
How about something with 2 x EL84s and 3 x 12AX7s?. (The 22V winding might be okay for a relay supply)
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: bmccowan on March 30, 2023, 07:49:51 pm
I believe a P-Classic 50 is 4xEL84. So it depends on your definition of smaller amp? Is 2x6L6 or 2xEL34 smaller? I guess, but not by much. Going smaller than that means scrubbing off a lot of power.
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: chris s on March 31, 2023, 12:53:09 am
Size, I was wondering I’d 5 to 20 watts was possible.
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: bmccowan on March 31, 2023, 07:00:33 am
It's "possible" but not practical or elegant IMO. I suggest thinking about what you want in the end; 5 - 20 watts is a big range, and then come back here for some advice. Certainly its possible to build something like an 18w EL-84 amp, but you'd be wasting a lot of power from that PT. 5 watts? - both the PT and OT are inappropriate for that.
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: DummyLoad on April 01, 2023, 04:12:32 pm
Cathode bias a pair of EL34 strapped as triodes, use the c-50 PT and OT.  Should yield about 20W.


--Pete
Title: Re: Small amp suggestion using Peavey Classic 50 parts
Post by: bmccowan on April 02, 2023, 12:37:07 pm
Quote
Cathode bias a pair of EL34 strapped as triodes, use the c-50 PT and OT.  Should yield about 20W.
When I saw this suggestion for Chris S' dilemma. It occurred to me that it was also an option for a 4xEL84 tranny set I have from a Baldwin Organ. I had been thinking of using that in a standard fare 2x6L6 amp.
In researching the strapped triode idea, I find that a lot of people like it for HiFi, but not so much for guitar amps. This includes a lot of folks who have wired up a pentode/triode switch and abandoned the triode idea.
So before I dismiss the idea, are there triode strapped amps out there that are well liked?