Power supply upgrades

Increase your filter capacitance, and replace your rectifiers with FREDs. I've done the former in the past(in tube amps) with excellent results. That's one of the first things most tube amp modders address, as it will improve the amp's bottom end performance and, overall, make everything sound more effortless. I just did the latter in both my SS woofer amp, and two Cary monoblocks. The results/improvements are too numerous to list, but the dynamics, slam and resolution you are seeking will be presented "in spades". I used a pair of IXYS VBE 17-06NO7 in my SS amp, and six IXYS DSEI 12-10A each in my Carys. Those are easily obtained from Digi-Key. How I wish that Black Gate was still manufacturing their large filter caps, or that Sanyo had OS-CONs big enough for amplifier power supplies. Al's filter cap/film cap bypass suggestion will also yield improvments. OOPS- I also recently upgraded the power supply in my TacT pre-amp, using FREDs and OS-CONs. Made a whole new beast out of it. I got carried away, talking about the power amp mods. SORRY! =8^) The tubes you choose will make a dramatic difference in your presentation also. Regarding the resistors: See if any of Caddock's will work in your app: (http://www.caddock.com/Online_catalog/Mrktg_Lit/TypeMK.pdf) Read the bottom of the data sheet.

What value bypass caps should those electrolytics be bypassed with?

I don't think it's particularly critical, as long as the bypass caps are of good quality. Anything from 0.1 to several uf strikes me as reasonable. If you find indications of particular values that worked well for people, in the forums you spoke of, go with those, but quality is probably more important than value.

Rodman -- As I think you indicated towards the end of your post, I'm not sure that the improvements you cited, which were mostly with power amps, would be relevant to a phono stage's power supply, where the current load is much more stable as well as much lower.

Regards,
-- Al

If he could find some Black Gates to directly replace the caps he has, there would definitely be an improvement with regards to dynamics. Some of their old suppliers still have the smaller values in stock, although at a premium. Upgrading to Black Gates, or Sanyo OS-CONs will improve dynamics installed in any circuit that provides gain. I believe he could easily find them for his phono pre. If the pre has rectifiers, replacing them with soft recovery FREDs will yield even greater benefits. These things just hold true, regardless of the power supply's application.

Rodman, my problem in replacing caps with Black Gates is firstly their size, the size of the circuit board is seriously limited. My old Cary monoblocks were all point to point wiring, much easier to swap out ps caps. Secondly, Black Gates are mostly lower voltage, 160v highest for 100uf, 350v for .22uf (I suspect enough here). Is the 160v rating high enough in this application?

I have investigated swapping out rectifiers, the problem is severe space limitations. I have two bridge rectifiers, RS804 and BR310, building my own from FREDs looks impossible to fit.

Caddocks are on my list of possible resistor upgrades.

Al, I'm willing to try premium electrolytics, at this point I'm leaning towards trying the bypass solution to begin with, if that works, fine, if not, try the upgrade electrolytics route. At the very least it would be an interesting experiment. What do you think about the 160v rating on 22uf caps, enough?

I've been doing a bit of investigating on the new Takman 'ultra premium' resistors. Sound very promising considering the few who have tried them. These would go in the signal path. Anyone have experience with these?