New rebuild - 6F12P-6P45S Triode

[kodabmx]

New update: I've changed the output tubes to 6P36S, and installed an AB-Q from Pavel at Audioamp.eu

I'm very impressed with these 6P36S. Definitely a sleeper.

New OP is 350V@60mA, 2k2 Ra-a. They are rated at 12W Pd, but have more metal than a 40W KT88

 

[Junm]

My 6P36S PP amp with same 6F12P concertina driver works great however it's not trioded and have 5k opt. they rocks..

 

[piano3]

Koda, the reason they are a sleeper must be that nonsensical power dissipation rating on the datasheet; they can obviously take at least 25 watts. Plenty around and cheap.

 

[ncc]

New update: I've changed the output tubes to 6P36S, and installed an AB-Q from Pavel at Audioamp.eu

I'm very impressed with these 6P36S. Definitely a sleeper.

New OP is 350V@60mA, 2k2 Ra-a. They are rated at 12W Pd, but have more metal than a 40W KT88

That's great, I have some 6P36S that destine for a new project, can you update us with your latest schematic?

 

[kodabmx]

I got 8 of these tubes "As-is used untested" for $6 plus shipping. I've bid on another lot!

Here's the schematic for the 6P36S triode connected setup.

 

[kodabmx]

A gratuitous photo of the current amp. Not seen in the photo are the 6Z4 tubes sitting between the front and rear 6D22S tubes...

Also a copy of the current power supply schematic. Ignore "one for each output tube" since it's now using the AB-Q module.

Anyone else think those KMH capacitors are fake? They work fine but I'm pretty sure they don't make a KMH at 820uF/450V...

OH! And the idle power consumption is now 300W on the button, and 0.91 PF.

 

[kodabmx]

Ok. I made one more addition. A 0B3/VR90 VR tube to drop -170V to -90V so the amp doesn't take 150 seconds to bias up

Digikey's Scheme It doesn't have a symbol for a VR tube, so I used a zener symbol.

 

[piano3]

Koda, what is an "Amigo" choke?

 

[kodabmx]

Koda, what is an "Amigo" choke?

Made by Amigo. They are probably long gone, but I got them at A1 parts in Toronto. They cost 5 bucks.

 

[piano3]

Yes, they must be gone; I couldn't find anything about them. 5 bucks is good! Are you still liking the 6P36S?

 

[kodabmx]

So far so good. Still testing though...

 

[hendrixgr]

Hi.
How much power they produce and at what anode voltage in triode mode?
I know that in tetrode mode they work fine but the OPT must be about 1.6K anode to anode if i am right.
I just got 10 for 40 dollars and some sockets to use in place of the 829B just for fun!
Chris

 

[kodabmx]

I'm using 350V, 80ma, 2k2 Ra-a. Calculations say they make about 40W.
The 6P45S was running 320V @ 120ma, They were good for 60W, but if you drop the load to 1k3 Ra-a, they make ~ 100W.
Alternatively, if you use 5k5 Ra-a, you make a ~25W class A amp.

 

[hendrixgr]

That is very encouraging information, thank you!
Chris

 

[kodabmx]

Any time

 

[kodabmx]

Thought I'd share a new picture... I swapped the 6P45S for 6P36S and made a new chassis...

 

[Francois G]

Have you modified the circuit or is this still according to the schematic in post #45? I see 6SN7s in the photo, but not in the schematic.

 

[hendrixgr]

Now that's a lovely tube amplifier, i will make one myself!
Thank you Kodamx!.

 

[kodabmx]

Have you modified the circuit or is this still according to the schematic in post #45? I see 6SN7s in the photo, but not in the schematic.

No, sorry. Here is the current schematic.

 

[hendrixgr]

Measurements?
How much power dos it have triode connected?
Output transformer primary impedance?

Chris