6V6 line preamp

[stajo]

Try like a 1000 uF min 50 V on the lower resistor in the divider. Ie between center of divider and ground.

 

[yellowbanana]

did you put an ecap on those voltage dividers lifting the filaments?

Hello Ajt,

I put in a 100uf cap at the lower end of the divider after the first clc filter not the last one... will using a higher value capacitor on the divider and moving it to the last LC help?

Thank you

 

[yellowbanana]

Hello Salas and all,

I very much would like to dc regulate the heaters... Id llike to get rid of the noise...I only have a 5.7 v ac at 2 amp and 6.7 vac at 1.5a winding available... will it still work?

Thank you

 

[yellowbanana]

Try like a 1000 uF min 50 V on the lower resistor in the divider. Ie between center of divider and ground.

I will try as you say... I think I do have that value.. also should I move the divider at the last LC filter of the supply?

I am using clclc supply..

Thank you for the help

 

[stajo]

I will try as you say... I think I do have that value.. also should I move the divider at the last LC filter of the supply?

I am using clclc supply..

Thank you for the help

No. Keep it early in the filter. Otherwise you will get AC on B+

 

[stajo]

Hello Salas and all,

I very much would like to dc regulate the heaters... Id llike to get rid of the noise...I only have a 5.7 v ac at 2 amp and 6.7 vac at 1.5a winding available... will it still work?

Thank you

You can put those in series and you'll have more then enough voltage for regulated DC.

 

[yellowbanana]

You can put those in series and you'll have more then enough voltage for regulated DC.

And just share the single supply for both the heaters?

Ty

 

[stajo]

And just share the single supply for both the heaters?

Ty

Yea. You could use 2 regs on one feed. If your gonna make as Salas 317 CCS I recommend choosing the series settings resistor size very carefully. 6V6 is just a spec and when controling voltage with current different tubes will vary alot.

I did some experiments on that way back in posts.

 

[yellowbanana]

Hello guys,

Is it okay to put a virtual center tap from the heaters to the ground with two matched resistors even if the heaters are elevated?

Thank you...

 

[stajo]

Hello guys,

Is it okay to put a virtual center tap from the heaters to the ground with two matched resistors even if the heaters are elevated?

Thank you...

No. Then you first reference heater center to ground and then to your elevated voltage. You can put the virtual center to your elevated voltage on the divider tho, or just skip the divider/elevating and tie it to ground.

 

[yellowbanana]

Thank you stajo... will do that and report back...

Best regards

 

[stajo]

Thank you stajo... will do that and report back...

Best regards

If it does your thing, one 200 or 220 k from each filament secondary could be upper resistor and the decoupled 10 k could be lower in your voltage divider.

 

[buzzforb]

I am considering trying a 6ax4 graetz PSU for my rebuild. I have the chokes and caps, so why not. Wandering if I am correct in assuming that I will drop about 15-18V across the 6ax4's for about 80-100mA of current needed for dual regulators. Do I need to quadruple this if using a graetz configuration. Here is the schematic I am using.
http://1.bp.blogspot.com/_ZXzBbxBRj...c/i_zXDoVqTHw/s1600/6CB5A-PSU-Graetz-6AX4.jpg

Perhaps a better question. How important is the setup before the SSHV2. Does it negate fancy PSU setups?

 

[Salas]

I don't know about the Graetz 6AX4 drop question out of hand, maybe some other guy knows. Enough SSHV2 users claim when giving feedback in the threads that they can hear even nicer things if good rectification and filtering is feeding it.

 

[buzzforb]

Thanks. I'll start a thread about the 6AX4 V drop. Want to get the right transformer.

 

[vgeorge]

Or get a custom one with a few output voltage taps and have good heat sinking for the SSHV2 just in case you need to drop some more volts.

 

[stajo]

Thanks. I'll start a thread about the 6AX4 V drop. Want to get the right transformer.

Your amp will draw some 30 watts of 6,3 V rectifier filament power. Have a sturdy tranny for that?

Sheet says 32 Vdrop per tube http://frank.pocnet.net/sheets/049/6/6AX4GTB.pdf. My guess is that your drop will be somewhere there.

 

[buzzforb]

Graph at the bottom seems to show that Vdrop is dependent on current through diode, same as with SS. I may be reading it wrong. Two SSHV2 will far roughly 100mA if we go for double the channel bias. That seems to correlate with a 17V drop across the diode/tube. Lundahl 1650 has 4 6.6V windings at 3A. Use two for rectifier, two for 6v6 regs. Also have two Antek toroidal that could provide similar configuration. I want this to be the last time. Have cases designed for main box, just working on PSU box.

 

[stajo]

Dont forget that this Vdrop is from DC to DC. Your going AC to DC. Set a load and measure is what I would have done.

 

[buzzforb]

I'll use what I have on hand to test if I cannot get more info on the forum. I see what you mean now about AC to DC. Thanks for the clarity, Stajo.