Kid "safer" PP 6550 amp

[battradio]

Hi Blair ,

A good 3 amp fast switching diode , A Mur4100E is what I use for B+ rectification and as a Flyback diode reverse polaritiy to ground between the two chokes in my 6B4 amps , to clamp off the reverse spikes

[kheper]

http://www.turneraudio.com.au/audiofilterchokes-page2.html

I am looking at this PS site from Patrick Turner (the traditional choke input), and noticed that the 6K bleeders are 30W! Dow these really have to be 30W?

He is figuring (815V * .042A = 34.23W). His power supply is 410-0-410. There are 2 6K resistors in series. A 10W 220K bleeder is more typical.

The other question is that the second choke I have is only rated at 715 WVDC. My supply transformer is 1100VCT. Would a current limiter help the startup spikes? Is it OK to use the 715V choke in the second position?

Thanks!

Blair

You may be safe if the hi-pot is greater than 1500V. Then again, Battradio's snubber is good insurance.

[Blair]

Hi Blair ,

A good 3 amp fast switching diode , A Mur4100E is what I use for B+ rectification and as a Flyback diode reverse polaritiy to ground between the two chokes in my 6B4 amps , to clamp off the reverse spikes

Do you have a schematic if the fly back you use? The ones I find are a loop back around the choke?

[Blair]

I've been soliciting some advice on DIYAUDIO regarding choke inputs. Here is the proposed layout.



Here is the power supply as suggested over there.



Should be a solid pair of monoblocks:)

[kheper]

Nice design. "Is this needed?" The resistors are there for safety and protection. They drain the power supply caps quickly (maybe 10 seconds), so you don't get zapped when fiddling around in the amp before the caps drain normally. Plus, when you turn the power supply off then on before the caps drain enough, you can produce a "voltage doubling effect", frying the power supply caps. Even with the bleeder, I would let the amp off for much longer than 10 seconds before turning it back on. (See my remark above about why Turner chose 30W for the resistors. 35W would have been better. He also is using the resistors to dampen the turn-on spike. See below: "May not be needed if soaring B+ of +815Vdc is OK".)

[Blair]

This project is actually coming to fruition. I had to start cleaning my living room before the holidays:)

Anyway, I just drilled two 9-pin holes for drivers. I think I'm going to go with something like the Poseidon using the 6CG7 vs 12AU7. The issue is I am not a fan of the 12AX7. Any suggestions for a different driver that offers low distortion and sounds a but different than the 12AX7?

Thanks!

Blair

[WA4SWJ]

How about the 5751? Lower gain but more than enough for your application.

Regards,

[Blair]

I had thought about the similar 12AT7, as well as even going all 6CG7.

I suppose I could try to make sure to leave enough space to easily mid the circuit for various tubes to fit my tastes.

Thanks,


Blair

[DeathRex]

If you use a 9AJ base you can switch out between a 6DT8 (6 volt 12AT7), 6BZ8, 6CG7, 6DJ8, 6BQ7, 6N1P, 6N23P, or 6H30.

[Blair]

Here is a top plate with transformers next to a size 12 sandal. Until the power transformer was mounted, they were very deceiving. They a huge!!

[Blair]

http://www.diyaudio.com/forums/tubes-va ... ply-9.html

Kind of a cross post, but different folks hang out here. I'd like to get as much input as I can before bringing this up on a variac:)

Starting around mid-page 8 is where I am. I have a question regarding the HV reference on the secondary side of the Triad.

Thanks for any help!

Blair

[Blair]

Here is a visual. I have it wired the way I drew it on the bottom. I think I need to do it the way it is on the top where I doctored the image.



Am I right?

Thanks!