Dropping B+ to simulate the equivalent of a 5Y3, sans sag?

[Structo]

I used a 25 watt Zener, then tacked a .01uf ceramic cap right on the side of it with the other lead to the conductor.
No noise.

And it dropped exactly the voltage it was rated at.

[M Fowler]

http://www.sourceresearch.com/nte/Zener ... 0-Watt.cfm

Mark

[dehughes]

Wow...that's expensive for one Zener.

[M Fowler]

I would get the correct PT and use the old one for another project or sell it.

Mark

[dehughes]

I would get the correct PT and use the old one for another project or sell it.

Mark

Yeah, that's what I'm thinking... I just don't have the chassis space for a large Zener, or even a small zener and a voltage regulator. I hate to go back to where I started from, but...sometimes you just have to cut and start over.

As for the "correct PT"...I'm not sure what that'd be, as I essentially have a cathode biased Brown Deluxe but with one channel being a 6SN7 (which draws more current, both heather and plate, than a 12AX7). Any suggestions?

[Firestorm]

The Hammond 272BX would do the trick (300 - 0 - 300 VAC secondary, 5V@2A and 6.3V@3A) but it's available only in X mount. You might contact Moose and see if he has any of the Heyboer transformers he has made for the Express amps in a Z mount. These have 300 - 0 - 300 secondaries and 5V and 6.3V windings (both with more current capacity than you'll ever use). As with the Hammonds, you'll have to check the size.

Out of curiousity, have you considered converting to fixed bias? The rectifier tube will sag the power supply anyway, so cathode bias sag may not be needed. And you could adjust the output tubes' operation for your existing plate voltage. Just a thought. The 6G3 was fixed bias, wasn't it?

[dehughes]

The Hammond 272BX would do the trick (300 - 0 - 300 VAC secondary, 5V@2A and 6.3V@3A) but it's available only in X mount. You might contact Moose and see if he has any of the Heyboer transformers he has made for the Express amps in a Z mount. These have 300 - 0 - 300 secondaries and 5V and 6.3V windings (both with more current capacity than you'll ever use). As with the Hammonds, you'll have to check the size.

Out of curiousity, have you considered converting to fixed bias? The rectifier tube will sag the power supply anyway, so cathode bias sag may not be needed. And you could adjust the output tubes' operation for your existing plate voltage. Just a thought. The 6G3 was fixed bias, wasn't it?

You know, I had actually considered converting it to a fixed/cathode bias (switchable...) setup, but opted for installing a negative feedback switch instead. I find that I prefer the vibe of a non-negative feedback, cathode biased amp over a fixed bias amp with feedback. As well, I have a particular goal in mind with this setup (compress-y, saggy, gainy cranked sounds but with big, soft, airy low volume cleans) so I think I'll see what Moose has lying about.

Thanks for the ideas! Much appreciated...