May 21, 201511 yr Found that there is nothing wrong with the pot. When I saw that the measurements of each section at a particular rotation weren't really far off, it didn't jive with what I was hearing. I found some connection issues; 2 crushed pins on the L out from the pot, and 2 broken wires on the input cable from the L jacks (that were still making some connection). Once fixed, it sounds much better now. This is the first time working with the radio shack rainbow wire (a favorite of rickcr42 from HF, RIP), and I can't say so far that I am a fan, other than it being ribbon and solid core. The insulation absolutely sucks as it melts if a soldering iron looks cross-eyed at it. So, in the words of the immortal Emily Litella, "Nevermind, bitch".
May 22, 201511 yr Pics (iphone) Input jacks with switch for RCA/XLR Amp boards and pot Sigma22 psu and transformer, set for +/- 16.2Vdc (gain resistors still socketed). L channel amp board. Still have the bias resistors (R38/39) socketed, 301R in there currently, resulting in 18-19mA current in the output stage. Also using 2SJ74/2SK170 JFET input. I also didn't populate the 4.7uf Wima caps as I'm not sure there is any point to them being there. Sounds very good, still evaluating compared to my other Dynalo. Dead quiet. I have only tried SE inputs so far, and don't notice any difference between the switch up (- inputs into the amp tied to ground), or down (- inputs wired to XLR but floating). Gain seems sufficient now that I have the input wiring issues sorted. It will be awhile before I case this, so I just mounted it to some scrap veneered plywood I grabbed from home depot for a buck, stained and polyed. EDIT: small pieces of clear tubing used as board standoffs, in case anyone was going to chastise me for mounting them directly to the wood Edited September 3, 20178 yr by Pars
May 22, 201511 yr @pars what are those connectors you're using for PSU and input/output? btw nice airy chassie you have there .... have one almost similar ...please don't comment on my dips Par
May 22, 201511 yr I/O connectors are Molex KK 0.100" such as Mouser 538-22-10-2031. The PSU connectors are Molex SPOX 0.200" such as Mouser 538-10-32-1031. And your sockets...
May 28, 201511 yr where did you get the power supply board? A Taiwanese kit & film cap supplier called ucc http://ucccap.myweb.hinet.net/ mine is older version
May 28, 201511 yr looks like all the parts are available to build that. 2sk170GR, GR only. A board to do that would be pretty trivial if we can't buy in the usa. Still going to cost more than a standard linear I think.
May 28, 201511 yr I have the standard linear stuff, it's just a bit on the large side for the case I pictured earlier. Also more difficult to disassemble than I first thought. Oddly enough I can probably fit some 7x15 -> Jung regulator inside. I agree though, for the prices at which you can get used all-in-one linears they're almost no brainers. http://www.ebay.com/itm/Power-One-HAA15-0-8-A-Regulated-Linear-Power-Supply-HAA1508A-12-OR-15VDC-5VDC-/141677351787?pt=LH_DefaultDomain_0&hash=item20fca0d36b Careful getting these shipped though, they're as dense as they look...as are the people shipping them
May 28, 201511 yr A Taiwanese kit & film cap supplier called ucc http://ucccap.myweb.hinet.net/ mine is older version UCC is a popular DIY supplier and has been around for some time. The dual-rail power supply is available both as a complete kit for roughly $43 US or PCB only for roughly $4 US. I was not able to find the shipping charge to US. It also appears that the store only accepts cash - the buyer is instructed to send cash to the store via registered mail.
May 28, 201511 yr this power supply performs no better than the fully regulated alternate krell ksa5 power supply so it may be easier for people to do that.
May 29, 201511 yr How big are these things? I only ask because I did a half sigma22 layout (only 1 pair of output FETs) and used it in a CD player to power the I/V stage. Board on the right. I didn't bother heatsinking the output FETs on this because of the low current draw.
May 29, 201511 yr this power supply performs no better than the fully regulated alternate krell ksa5 power supply so it may be easier for people to do that. That's the one I was looking at originally, maybe it's time to put in a order. Need some BHSE supplies anyway
May 29, 201511 yr Do they ship internationally? I can't beat that size yes he can do international shipping can contact him by mail
May 29, 201511 yr The alternate krell supply is bigger than it needs to be, because I made it the original size, will look into shrinking it a bunch.
May 29, 201511 yr sounds good, I can send you any extras that bay area throws my way if you want Are they worth using in the NFB preamp too?
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