[FallenAngel]

The maximum 1st capacitor size after the rectifier tube is 50uf. So if you mean two 100uf in series, resulting in an effective capacitance of 50uf, that should work. 

I was talking about the amplifier board, output caps. I also meant in parallel.

 

[ericj]

Sure. Go nuts. 

 

[FallenAngel]

Still trying to figure out the layout.

 

[FallenAngel]

Hey tube amp guys,

Layout design help please if you could spare the time.

 

[Johnthurston]

Is this going to be a fully enclosed chassis? That is, front-mounted controls with everything inside the case and nothing protruding? If so, those caps are going to make it pretty tall, aren't they?

 

[FallenAngel]

  Is this going to be a fully enclosed chassis? That is, front-mounted controls with everything inside the case and nothing protruding? If so, those caps are going to make it pretty tall, aren't they?

 
Yep, fully enclosed. The chassis is 6" tall.
 
I'm kind of sticking to the layout in the photo.

 

[FallenAngel]

Wiring layout. What do you guys think?

 

[FallenAngel]

Just a quick and simple question : 6N6P-i or 6N6P?
 
Looks like 6N6P is fine.

 

[FallenAngel]

Another question : C5/C6 - can I drop it down to 200V?
 
Looks like it's possible, but highly not recommended.

 

[FallenAngel]

Bizarre initial setup...
 
Left channel LED is on, but the sound is nothing but buzz.
Right channel LED is off, but the sound is good.
 
I'm looking into what's going on. Change of 6N6P tubes does nothing.
 
3 tequila drinks at lunch isn't helping my concentration and I can't see anything wrong with the board...

 

[FallenAngel]

"Progress" - one step forward one step back.
 
I had a solder joint between R1 and pins 6 and 7 on V1 (6922 tube) by a little solder splatter when I was doing the wiring in the chassis. No more LED light issues, heaters all work - around 6.9VAC.
 
The amp plays music and sounds "OK, I guess", but here's the issue. The PSU is set to 250VDC output without the amp boards connected. When I plug in the amp boards though, it drops down to around 130V.
 
With such a huge drop in B+, it's not realistic to check the voltage points on the amp board because it would all be skewed.
 
I'll look around closer today and update. Any initial thoughts would be appreciated though.
 
I'm using EZ81 rectifier, 6922 input and 6N6P output tubes.
 
Thanks!

 

[FallenAngel]

It looks like it takes a few seconds to stabilize at 250V on the PSU. It holds voltage consistently.

Once I connect either board, B+ drops to 140-150v and with both amp boards connected it shows 115v.

Resistor values on both boards should be correct. Before I start checking every component by hand separately, sent ideas?

Thanks

UPDATE : After many hours of reading through about half of this entire thread, I've answered a lot of my questions (as above).

Next up is to check if I fried my MOSFETs with a 100KOhm test load and confirm that they can just be replaced.

One thing I'm still not clear on is what characteristics of a MOSFET I should look for when selecting one for this application. After pouring through datasheets of the two recommended ones, I don't see why I can't just throw an IRF820 in there instead of the IRF820B.

 

[FallenAngel]

Update:
 
Tested the PSU with a 100K load resistor and after a bit of back and forth for about 30 seconds, it stabilized at 250V. Still the same issue exists when connecting the amp boards.
 
I'll try to replace the IRF820B with some IRF840 tomorrow and see what happens, but other than that, I'm out of ideas.

 

[FallenAngel]

Just as I thought thanks to the copious amounts of knowledge in this thread, blown IRF820. Replaced with IRF840 and she sings like an angel.

 

[dBel84]

Home sick today and browsing all sorts of fun things - glad to hear you got this sorted. Looks like an impressive iteration of an old favourite..dB