#26 pre amp - Page 147

massimo · 29th December 2011, 07:04 PM

Very nice George, congrats
Just a question: where did you connect SSHV2 sense + and -?
Sense + to the #26 anode and sense - to the star gnd?

vgeorge · 29th December 2011, 07:08 PM

Maybe 170Vdc. Pls, either simulate or make a test. There is going to be some voltage sag.
I like to have higher voltage transformer and adjust B+ with a small capacitor in front of the choke.

vgeorge · 29th December 2011, 07:13 PM

Quote:

Originally Posted by massimo

Very nice George, congrats
Just a question: where did you connect SSHV2 sense + and -?
Sense + to the #26 anode and sense - to the star gnd?

Correct, but as I use a transformer, sense and force + to it' s input, not to anode.

merlin el mago · 29th December 2011, 07:20 PM

Wich dimensions have your chassis?

massimo · 29th December 2011, 07:33 PM

Quote:

Originally Posted by vgeorge

Correct, but as I use a transformer, sense and force + to it' s input, not to anode.

Thank you. I asked this question because I saw a red wire coming out from the SSHV2 going apparently to the tube anode. I was wrong then.

vgeorge · 29th December 2011, 07:52 PM

It's one red wire coming from the transformer. Two red wires leaving SSHV2 going to transformer.

andyjevans · 29th December 2011, 10:03 PM

I think there's a growing bunch of people who see filament bias as the best sound you can get out of the 26. I know most of you don't start with a small cap (220uF) and choke input before the filament reg, but I found this gave a nice increase in sound quality. I use 280mH chokes rated at 2.7A - simply because I bought a few off a dealer. But Hammond chokes are another option.

We seem to be moving towards a "standard" design with filament bias and a Salas reg. LL1660 seems to be the default transformer option, but I'm sure there are some tasty hand made options out there as well, and there are some very skilled winders on this forum.

andy

vgeorge · 30th December 2011, 03:26 PM

Quote:

Originally Posted by merlin el mago

Wich dimensions have your chassis?

43X33cm PS unit 43X26

merlin el mago · 30th December 2011, 03:37 PM

Thanks George have a Happy New Year.

Cheers,
Felipe

albertli · 31st December 2011, 06:55 AM

Quote:

Originally Posted by Rod Coleman

Hi George, Looks like good layout and build!

Voltage Rating for Filament Bias:
With correctly specified C1 and R8, any new kit can be configured to run Filament bias up to 45V or so at the input.

With changes of transistor 200V is possible - though I can't imagine it is needed.
Flexible operating voltage - the beauty of discrete-transistor design! New V4 kits are available for Filament bias.

Hi Rod,

I still have a pair of your boards sitting on the bench of which brought out from you almost 6 months ago. I'm going to cut my chassis and lately found that people have good result on filament bias. Are my boards suitable for the purpose by changing some value of parts ?? Please kindly advise.
Regards

Albert

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29th December 2011, 07:04 PM	#1461
massimo diyAudio Member Join Date: Dec 2002 Location: Milan, Italy	Very nice George, congrats Just a question: where did you connect SSHV2 sense + and -? Sense + to the #26 anode and sense - to the star gnd?

29th December 2011, 07:08 PM	#1462
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	Maybe 170Vdc. Pls, either simulate or make a test. There is going to be some voltage sag. I like to have higher voltage transformer and adjust B+ with a small capacitor in front of the choke.

29th December 2011, 07:20 PM	#1464
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Wich dimensions have your chassis?

29th December 2011, 07:52 PM	#1466
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	It's one red wire coming from the transformer. Two red wires leaving SSHV2 going to transformer.

29th December 2011, 10:03 PM	#1467
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I think there's a growing bunch of people who see filament bias as the best sound you can get out of the 26. I know most of you don't start with a small cap (220uF) and choke input before the filament reg, but I found this gave a nice increase in sound quality. I use 280mH chokes rated at 2.7A - simply because I bought a few off a dealer. But Hammond chokes are another option. We seem to be moving towards a "standard" design with filament bias and a Salas reg. LL1660 seems to be the default transformer option, but I'm sure there are some tasty hand made options out there as well, and there are some very skilled winders on this forum. andy

30th December 2011, 03:37 PM	#1469
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Thanks George have a Happy New Year. Cheers, Felipe