GSG Build Thread - Questions

[DualTriode]

Well I have had a GSG board for about a year and I am finally planning a build for it. I will probably have plenty of questions along the way. First off, can I use 470K Ohm resistors in R1,R2,R9,R10 in place of 475K without any problem? Also, 3K instead of 3.01K in R5, R6. The brand I want to use doesn't offer the values suggested. If there could be any issues, I will find exact values.

Would this Antek power transformer be OK? - http://www.antekinc.com/details.php?p=730 . I have used Antek units in the past and I really like their quality.

Anybody know a source for James Audio chokes?

Is the James 6112HS or 6113HS preferred?

Answers to these questions will really help me get these items ordered and this amp started.

Thanks in advance

-Madison

[DualTriode]

Or the James 6115HS?

[Shannon Parks]

First off, can I use 470K Ohm resistors in R1,R2,R9,R10 in place of 475K without any problem? Also, 3K instead of 3.01K in R5, R6. The brand I want to use doesn't offer the values suggested. If there could be any issues, I will find exact values.

No problem to sub with these values.

Would this Antek power transformer be OK? - http://www.antekinc.com/details.php?p=730 . I have used Antek units in the past and I really like their quality.

It looks OK, but your filament voltages will probably be on the high side as it is spec'd for 4A on each tap. I guess maybe adjust R19 & R20 to 1 ohm, 3W if needed.

Anybody know a source for James Audio chokes?

Is the James 6112HS or 6113HS preferred?

I don't know about James chokes. Either one of those outputs would work fine - just use the 3.5K tap. Don't use the 6115HS, but that would work OK in a Clementine (5K).

Shannon

[Shannon Parks]

First off, can I use 470K Ohm resistors in R1,R2,R9,R10 in place of 475K without any problem? Also, 3K instead of 3.01K in R5, R6. The brand I want to use doesn't offer the values suggested. If there could be any issues, I will find exact values.

No problem to sub with these values.

Would this Antek power transformer be OK? - http://www.antekinc.com/details.php?p=730 . I have used Antek units in the past and I really like their quality.

It looks OK, but your filament voltages will probably be on the high side as it is spec'd for 4A on each tap. I guess maybe adjust R19 & R20 to 1 ohm, 3W if needed.

Anybody know a source for James Audio chokes?

Is the James 6112HS or 6113HS preferred?

I don't know about James chokes. Either one of those outputs would work fine - just use the 3.5K tap. Don't use the 6115HS, but that would work OK in a Clementine (5K).

Shannon

[kheper]

Would this Antek power transformer be OK? - http://www.antekinc.com/details.php?p=730 . I have used Antek units in the past and I really like their quality.

-Madison

If you want to use a Full Wave, solid state rectifier (instead of the 6AX5GT), the Antek transformers, below, will yield a B+ lower than the PA-774. Less voltage dropping needed, than with the PA-774. Further, they have 3A heater windings, not 4A as with your Antek, and their current capability is the same as or higher than the PA-774.

http://www.antekinc.com/details.php?p=672

or

http://www.antekinc.com/details.php?p=671

or

http://www.antekinc.com/details.php?p=670 (Might be a little shy on voltage for Shannon's circuit.)

To create an "Artificial Center tap" and to lower the heater voltages, see:
http://www.valvewizard.co.uk/heater.html

[DualTriode]

If you want to use a Full Wave, solid state rectifier (instead of the 6AX5GT)

Would this Weber solid state rectifier work as a drop in replacement for 6AX5GT, I would like to be able to use both. The unit is called the 'WAX5' and can be found here http://www.webervst.com/ccap.html.

As far as the power transformer..

I see the PA774 is (330-0-330, 180ma). (6.3 X 2, 2.5 A)

The Antek Unit http://www.antekinc.com/details.php?p=673 seems very close.

[DualTriode]

I am planning on using 2 chokes. Would there be much advantage of using a bit larger chokes? I have seen some use 5H chokes on this build. I am looking at these edcor units.

http://www.edcorusa.com/p/775/xc75-2h-200ma
or
http://www.edcorusa.com/p/783/cxc100-5h-200ma

Thanks in advance

[kheper]

If you want to use a Full Wave, solid state rectifier (instead of the 6AX5GT)

Would this Weber solid state rectifier work as a drop in replacement for 6AX5GT, I would like to be able to use both. The unit is called the 'WAX5' and can be found here http://www.webervst.com/ccap.html.

As far as the power transformer..

I see the PA774 is (330-0-330, 180ma). (6.3 X 2, 2.5 A)

The Antek Unit http://www.antekinc.com/details.php?p=673 seems very close.

You'll get the same 50V voltage drop from the WAX5 as the 6AX5GT. You will need to drop less voltage to match the schematic with the Antek, since it is only a 300-0-300.

The Antek AS-1T300 has less current capacity (170ma) than the PA774 (180ma).

The 6B4Gs appear to be biased at ~60ma per tube and the 6SL7 is biased at .6ma(?). So, you should be able to get away with 170ma, but I'd hold out for a transformer with more current capacity - for better performance.

[kheper]

I am planning on using 2 chokes. Would there be much advantage of using a bit larger chokes? I have seen some use 5H chokes on this build. I am looking at these edcor units.

http://www.edcorusa.com/p/775/xc75-2h-200ma
or
http://www.edcorusa.com/p/783/cxc100-5h-200ma

Thanks in advance

2 smaller chokes seem to smooth out more ripple than one bigger one. http://www.edcorusa.com/p/775/xc75-2h-200ma looks like a nice choke. The other edcor choke appears huge. 2 of the former edor chokes may be what you are looking for.