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I finally finished my 811 se integrated. Used Valve World's schematic, but didn't want a pentode in the front, because I didn't want global feedback. I started with 6AQ7s, but they didn't have quite enough gain, so I switched to 6SN7s cascaded. Getting about 10 watts out.

My firsts for this amp:
first DHT
first time using 6BD5GT (have to see how long they last) did have a used one that was gassy
first time veneering
first swirl pattern on aluminum

The big transformer is the 6.3 volt filament for the 811s.
There are additionally a power transformer, and 3 chokes underneath.
The lowest hum I could get down to was 8mvpp. With the volume pot in front of the 6AQ7s, hum was at 10mvpp. With the volume pot in front of the 6SN7s, I was getting 20mvpp. I tried putting DC on the filaments and everything else, just couldn't get it down. Even with DC on the filaments of the 811s, the 50 ohm adjustment pot is very touchy.

DeathRex wrote:The big transformer is the 6.3 volt filament for the 811s.
There are additionally a power transformer, and 3 chokes underneath.The lowest hum I could get down to was 8mvpp. With the volume pot in front of the 6AQ7s, hum was at 10mvpp. With the volume pot in front of the 6SN7s, I was getting 20mvpp. I tried putting DC on the filaments and everything else, just couldn't get it down. Even with DC on the filaments of the 811s, the 50 ohm adjustment pot is very touchy.

If there is room underneath, you could put chokes on the filament supplies. You might get away with one choke if you paralleled the secondaries and lost the hum-pots. Make sure the filament diodes can handle the current.

Nice retro-deco style on the wood and metal. The amp would have a more stunning appearance if you re-painted the old transformers.

Sweet!

Is the hum balance pot a multi-turn?

You can likely also reduce hum with a resistor loading the grid. 5-10K-ish.

Cheers!

kheper wrote:If there is room underneath, you could put chokes on the filament supplies. You might get away with one choke if you paralleled the secondaries and lost the hum-pots. Make sure the filament diodes can handle the current.

Nice retro-deco style on the wood and metal. The amp would have a more stunning appearance if you re-painted the old transformers.

Like the lady said working at the hotel during the democratic convention in New Orleans "Aint got no more room." The diodes are 17 amp schottkys. With most of my amps, I wanted a old and used look. Didn't want a old and then new look. And I like the diagram on front of the Triad.

Geek wrote:Sweet!

Is the hum balance pot a multi-turn?

You can likely also reduce hum with a resistor loading the grid. 5-10K-ish.

Cheers!

Nope just a single wire wound Alpha. You can adjust it and see the waveform change on the oscope. I just turned it to minimum. I can't hear the hum and better yet there is no hiss. I guess 8mvpp is about 2.8 mv rms. When you first turn it on, the 6BD5GT has ALOT of 60 Hz on it, in a perfect sinewave. It took me a while to figure out it would since there is no load on it. I had to really lower that second B+ to bias the 811s, I didn't know what would happen if I did add a load onto the cathode, so I didn't.

I wanted a old and used look. Didn't want a old and then new look. And I like the diagram on front of the Triad.

Love the Art Deco look. Where did you get the inlaid front piece?

Made it, got some veneer from ebay, cut it, and contact cemented down. The sides are cherry.

I think I'll try some linseed oil on the transfomers to liven them up. And adjust the white balance on the camera.

DeathRex wrote:Made it, got some veneer from ebay, cut it, and contact cemented down. The sides are cherry.

I think I'll try some linseed oil on the transfomers to liven them up. And adjust the white balance on the camera.

WOW. Great job on getting those 3 center pieces to join up. Did you use a scalpel on those cross-grain cuts?

Guillotine paper cutter.

Great job.

Not easy to do symmetrical veneer. Inside corners are tough.

John

DeathRex wrote:Guillotine paper cutter.

THAT is something I'd not thought of. Nice tip!

I thought those things were for cutting aluminum?

Here's a post lineeded pic with Oreo.

You KNOW you have a winner when it's kitty approved!

Gregg, is that a Hammarlund? Looks an awful lot like the HQ180 I have.

DeathRex wrote:Gregg, is that a Hammarlund? Looks an awful lot like the HQ180 I have.

Yup! HQ-170