And another amp, all indirectly heated

What people are working on at the moment
Post Reply
steve s
Needs to get out more
Posts: 1915
Joined: Wed May 30, 2007 6:19 pm
Location: east yorks

And another amp, all indirectly heated

Post by steve s » Wed Mar 18, 2020 5:01 pm

Just put this together last weekend
It had it's first run on my main speakers today. It sounds very nice
It's not quite the px4 sound, but it's very close. It's a bass monster mainly due to the driver valves. Early ac/hl do have a dark tone. Plays double bass beautifully.
The 2k sowter transformers are a little thicker in the bass too and not quite as airey as the tributes.
It's output valve is the Mazda pp3521 it's sort of an indirectly heated cosser 2p valve, the anode looks identical, 2.3 watts output. The pair you see where part of a group buy around 5 years ago ( thanks paul) and have been quietly awaiting some ac/dc application.
The output valves are on a dc heater supply, the black box on the front right running around 33 volts. It needed an extra cap close to the valves to silence a little hum, the amp is reasonably quiet.. but i could do better with it !!
The power supply is again a single tx split 4 ways.
20200315_220437_copy_1024x768.jpg
Attachments
20200315_233950_copy_768x1024.jpg
20200318_162734_copy_1024x768.jpg
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

User avatar
IslandPink
Oooo, Roberts Radio's sound nice
Posts: 7437
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

Re: And another amp, all indirectly heated

Post by IslandPink » Wed Mar 18, 2020 6:24 pm

Mister you're on fire Mister ! :)
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

steve s
Needs to get out more
Posts: 1915
Joined: Wed May 30, 2007 6:19 pm
Location: east yorks

Re: And another amp, all indirectly heated

Post by steve s » Sat Mar 21, 2020 6:18 pm

Hardly used the hifi this week
Lesley decided we should decorate as we are not going out.. I told her I'm not spending the last couple of months of my life decorating
But I commited to a full week of jobs around the house.
A new roof on the log store, a couple of trees removed and logged and two new radiators fitted in the lounge. Just finished this afternoon.
All jobs I hope to get the benefit of !

Back on with this amplifier today.
The pp3521 valves are really very good. Not alot different to the px4 amp.. all this directly heated is best stuff I've read over the years.. to find its not much different.
Anyway enjoying the amp. I may well build this into a case, it would be good to have.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

User avatar
Ali Tait
Social outcast
Posts: 3756
Joined: Fri Jun 08, 2007 8:10 pm
Location: Dunfermline

Re: And another amp, all indirectly heated

Post by Ali Tait » Sat Mar 21, 2020 6:50 pm

Shoddy!
Image[/img]

User avatar
Dave the bass
Amstrad Tower of Power
Posts: 11252
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

Re: And another amp, all indirectly heated

Post by Dave the bass » Sat Mar 21, 2020 8:05 pm

What comes after Peta-Shoddy?

Exa-Shoddy I think, thats what this is anyway.
"One pound of middle cut pork leg joint,
Stew my foot and call me Brenda".

Post Reply