old thread

[utervo]

Lots of work here for a Champ. Good thing you're not building a Deluxe Reverb

Not much work, just a lot of talk!

[Mark]

http://www.hifitubes.nl/weblog/wp-conte ... -6v6gt.pdf

http://frank.pocnet.net/sheets/049/6/6AQ5A.pdf

http://en.wikipedia.org/wiki/6AQ5

I'd consider the zener voltage reduction circuit instead of VVR.

Are you having any issues with the 6AQ5A?

[utervo]

I'd consider the zener voltage reduction circuit instead of VVR.

Are you having any issues with the 6AQ5A?

No but I am a bit worried it can't take the voltages.

Would 3 24V/5W Zeners in series be ok, can they take the load of a 5F1?

[utervo]

Or maybe 8 pieces of 10v/5W zeners to avoid too much heating per zener?

[utervo]

Gonna try with 15V / 5W Zeners and a 0.1uF cap to suppress noise.

[Mark]

I can't but help think your doing this the hard way. Try putting a 330 ohm or 470 ohm 5 watt resistor between the valve rectifier and the filter caps.

If the 330 ohm resistor drops any more than 40VDC you will need a 10 watt resistor.

Start with the easy fixes and move towards the more complicated options.

[rp]

I'd consider the zener voltage reduction circuit instead of VVR. Are you having any issues with the 6AQ5A?

No but I am a bit worried it can't take the voltages.

I'd do neither and switch to a 6V6. Drill or knock out for an octal assuming you have a base handy and a 6V6. Save money, ordering parts effort and time, save heat and energy, less parts = better reliability. Can always use an EL84 too.

[Mark]

Champs are a funny thing. I've heard plenty of talk about them having 50/60hz hum, though I recently heard some silver face Champ's that were dead quiet.

If the Champ has the typical power supply noise issue then I'd use the extra filtering stage to knock out the hum and to lower the rail voltage.

The hum can be incredibly annoying and you don't need a noise amp when recording.

[Roe]

I added a choke in mine ala 5e1 (although I knocked down the screens voltage a little). its quited and the bass is tighter

[utervo]

Anyone tried a 5v6gt, they are cheap?

[utervo]

Anyone tried a 5v6gt, they are cheap?

Apparently all my available 5V filament amps to to the 5y3gt already.

[rock_mumbles]

If you lower the voltages for the 6AQ5 the amp will get even darker because of the reduced preamp voltages ... one way to brighten up the amp would be to raise the preamp voltages.

You may need to do split power supply instead of having the nodes in series

[rdjones]

Anyone tried a 5v6gt, they are cheap?

Apparently all my available 5V filament amps to to the 5y3gt already.

You don't want to have a tube rectifier share the filaments with any other tubes unless the rectifier has an indirectly heated cathode that is not connected to the filaments.
Otherwise you have B+ on your filaments, and all kinds of problems.

The only way to use the 5V secondary on other tubes is to use SS diodes and isolate the B+ from the winding.

reddog

[utervo]

Thanks, that's good information. B+ isn't something I want anywhere else but where it should be.

[utervo]

Decided if I make new holes to the chassis (stainless), I might as well do more holes, so a complete rebuild reusing the expensive parts (chassis, iron etc.). I never was happy with the wiring anyways.

I have a few Tungsram 12ax7's and Philips 12au7's for this preamp and need to get a good 6v6gt instead of the 6aq6a. I combined the 5e3 preamp section and power supply with the 5f1 poweramp. The spare triode left is used as in 5f1.

I've not included the mods suggested for brightness, but plan to put a cathode cap switches, nfb pot/switch and lower coupling cap capacitance as discussed here.