[n_maher]

As promised, updated pictures...

Pete is reviewing the final schematic along with the last few questions that I had. I've also managed to dial out the last bit of noise on the inputs. I've got a temporary fix in place and will be adding a permanent solution at some point that will involve a ground lift switch on the inputs. Bottom line, with it in place I'm more likely to hear the fridge running two rooms away through a closed door than I am to hear noise in the background of the amp. :dance:

the amp guts

amp top panel

ps guts

ps top

I expect to have the schematic in the next couple of days and I'll post it up as soon as I do.

Listening again tonight, but with different tubes. 5U4GB's/RCA 6SN7/Cetron 5998s - sounds outstanding good to me.

 

[pabbi1]

You are a gentleman, and a scholar, taught by a master. Can't wait.

 

[naamanf]

Very nice Nate! I think I will need to add this to my list of amps to make.


<-Adds Menace to list of amps to make. Looks at wallet and time available and cries.

 

[n_maher]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif You are a gentleman, and a scholar, taught by a master. Can't wait.

One out of three ain't bad.

Quote:

Originally Posted by naamanf /img/forum/go_quote.gif Very nice Nate! I think I will need to add this to my list of amps to make. <-Adds Menace to list of amps to make. Looks at wallet and time available and cries.

Just wait till you start buying tubes... first you'll realize that you need a tube tester if you're really going to buy tubes and feel good about it. Then you'll realize that, geez, ya know, it really makes sense to have backups for your favorite pairs. And wait, there's those exotic hard to find pairs. My wife caught site of my tube stash for the first time this weekend and it was not good. Between rectifiers, inputs and outputs I'd say I'm up around 50 now.

And of course, thanks for the kind words. I put more than just a little bit of thought into both the physical and circuit layout and how I wanted the chassis to come together. There was still a bit of luck in pulling it off as close to my original vision as I did but it wasn't entirely be accident.

 

[naamanf]

Thank god my wife understands this insanity. Or at least she puts up with it. There are a couple local stores that have a large NOS and used tube collection with a tester.

 

[n_maher]

WARNING: The following schematics depicts a project that involves working with high voltages. Use of this schematic is permitted with the understanding that if you're not careful, this thing can kill you. Not only are you working with line voltages but the HV (B+) supply has a lot more current capacity than your typical tube project and should be treated with a great deal of respect. Getting hit by ~300V is no fun, assuming you live to tell the tale. That said with proper respect and care there's nothing exceptionally complex about this amp or power supply.

C3 Mistake: the first posted version of the schematic had the incorrect value for C3. If C3 and C4 don't show the same value for you you're still seeing the old schematic and need to clear the old image out of your browser's cache.


Schematic (updated 5/20)

Amp

PS

More information contained in post #2 of this thread.

 

[grawk]

this is a heck of a gift to the community you guys are giving.

 

[n_maher]

It was always Pete and I's goal to publish the design for private use so I'm glad - now I'm just hoping there's someone else crazy enough to build it! Also, if there's someone really crazy I'll provide information about an alternate power supply configuration that uses damper diodes instead of the rectifier types shown here. This disadvantage to that PS is that it would require an additional filament supply but it has other advantages that are worth considering.

 

[n_maher]

One quick correction - C3 on the amp schematic is supposed to be the same 10uF/400V cap used for C4. Please don't anyone build this w/ a 50V cap, that'd be a bad thing!

 

[grawk]

but capacitors make great firecrackers.

ref. first take on the balanced mosfet

 

[n_maher]

Quote:

Originally Posted by grawk /img/forum/go_quote.gif but capacitors make great firecrackers. ref. first take on the balanced mosfet

Except that this might make what happened in your PS look like childs play, instead of 2x the rated voltage we'd be looking at ~5x or more. I'm going to try hacking the jpg file this afternoon to see if I can fix it. It's been a bad Monday in the office though so for now the warning is the best that I can do!

 

[Ferrari]

Thanks for sharing the schematics with the DIY community. Looks good!

Dr. van Waarde amp concept is clearly visible: cathode follower (via grid stopper resistor), but with 2-halves of a 6AS7G in parallel, feeding by higher B+ voltage.

 

[n_maher]

I've updated the schematic to fix the C3 mistake - however it may require folks to clear their browser cache to see the correct image file. I did a direct replacement of the image file so that I didn't have to change links so the old image may show up for some folks for a while.

 

[Skylab]

I have to confess this looks like one helluva amp!

 

[grawk]

It sounds better than it looks, and I think it looks great.