[holland]

You're very welcome, runeight. It was interesting and a pleasure.

 

[dBel84]

You mean there will be no more changes

always a pleasure

..dB

 

[kostalex]

When the kits will be available?

 

[FallenAngel]

So do I take out Q1P or leave it in?

 

[holland]

I left it.

 

[wiatrob]

Runeight - you are entirely welcome, it has been quite an edifying experience.

Many thanks to you for your contributions to the hobby...

 

[onform]

Can we play now???

 

[wiatrob]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif So do I take out Q1P or leave it in?

Just to confuse matters - I took it out, I blew up about four during HV PS tweaks and the pads were in pretty bad shape. I think you are OK either way...

 

[runeight]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif So do I take out Q1P or leave it in?

My amp is back to its original PS section, but when I tested the new HV supply I took out the Q1 section, including the cap and resistor. Just like in the schematic.

Q1 doesn't really add anything to the PS when the regulator is in use and actually may be somewhat detrimental to the PS behavior. Hence its removal in the final design.

 

[holland]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif actually may be somewhat detrimental to the PS behavior. Hence its removal in the final design.

I think I missed that. Can you expound on it? Thanks.

 

[runeight]

Quote:

Originally Posted by holland /img/forum/go_quote.gif I think I missed that. Can you expound on it? Thanks.

It's not a big deal, but just a matter of tuning everything as best we can.

The ripple reduction from the regulator and the two final cap mulitpliers is enough for the B+ supply. However, each BJT that is added contributes some amount of noise to the B+. Q1 contributes some noise and so it's better to leave it out.

 

[holland]

Ah. That's understood. I thought you were going to say something about the cap multiplier interacting with the reg in a negative manner.

At least now I don't have to open up and fix that.

 

[pabbi1]

Anyone try any different opamps, or is it just not worth bothering? And, I haven't seen any discussion about solder vs socket on the opamps - any recommendations on the _correct_ Dip8 sockets?

I'm also reading a lot here about heat - will substantial bottom and top plate holes be sufficient for the Hammond 1455T2202? Standard config, 6.3v heaters, 5963 tubes mounted on the board.

 

[holland]

Not worth it. It's a servo.

Sure. I'm not exactly sure what you mean by substantial, but if you look at my case, I think it's fine with the amount of venting. I'm running 12.6v.

 

[runeight]

as holland says, opamps are just a servo. however, you can sub any high beta jfet input opamp with the same pinouts. if you happen to have some lying around. if you don't, however, just use the opa134s.

i recommend sockets though, just in case you have a problem and you accidentally destroy one of the opamps. this is unlikely in this amp, but it can happen with the right kind of short. almost any good quality 8 pin dip socket will work.

i think that 5963s are the best sound in my amp. they are 12.6V tubes, so the jumpers should be set to 12.6V. the tubes will run with heaters in parallel. if you use 6922s and similar, you'll set the jumpers to 6.3V so the tubes can run in series.