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Got this working, think it was floating input causing the problem. I dug up a pair of 12V regulators and put them in, but no joy. Turns out the positive reg was an ST Micro (probably one of the pair that I had problems with) and only put out 11.05V (vs. -11.9+V on the neg regulator, not ST Micro), which had the effect of unbalancing the reference voltage divider. Ref voltages were +0.05V and -1.01V, which didn't work so well Went back to just the bench PSU and it started working. I'll have to grab some more 12V regulators... have all sorts of 15V etc. but no 12V other than LM317/337s.

I only had 2 of the outputs tied together, but the inputs were floating (just a single 100k resistor). I'll tie both of these to ground. I am running this from a +/- bench supply and noticed the 100k/500k combo only ohmed out at 8k or so in series with the bench supply connected. Removing it and the resistance went up to 22k or so, which makes sense since the reference voltage divider is in parallel and is 23k. I may dig up some 12V regulators and wire them up to isolate the circuit from the bench supply. I also threw a 10uf film cap in in place of the electrolytic to no avail.

Have a version of this breadboarded right now and something doesn't seem right. I was going to modify this to put in a manual mute switch and a pair of LEDs. I only have a pair of inputs wired up to the LM339 (single right now), and at the junction of the 1K/100K/500K resistors and the cap, I am seeing -9V or so, feeding the gate of the FET. Relay is off. Since the relay is connected to signal using the NO contacts, I should think with no signal in, it should be ON and conducting the input signals to the output? I am using a 47uf electrolytic cap currently, with the - on V- and the + at the resistor juncture. I do not have the protection diodes in on the 2 inputs I have wired. The outputs of the LM339 are sitting at ~ V- unless I overload using a 9V battery. I've never used the LM339 before, particularly on dual supplies.

Try posts 312, 315 and 319 and around that area. You do realize that a single balanced dynahi board is 1 channel (+ and -)? Hope you got two boards...

Jocko seems to know his shit with digital/RF. Enjoy it, and mod carefully. Shouldn't be a problem to add a power switch, though this might be best left on. Some of Pass' preamps don't have a power switch (Aleph P for instance). And you can contact Jocko on diyhifi.org, though he is,umm, cantankerous

Happy Birthday!

I was thinking RN60s also, but for some reason they weren't coming up in my search on Mouser. I should have directly looked for them. Also, I have a couple of RN65s and they aren't that huge that with creative lead bending they couldn't work. Though I suppose at these voltages, you don't want to give anything an excuse to arc

Last fall, both HBO and Showtime announced unbundled services would be offered in 2015. It looks like HBO is available (HBO Now). Not sure when Showtime will be. http://www.fool.com/investing/general/2014/11/16/hbo-cbs-and-showtime-are-helping-you-cut-the-cord.aspx I guess if your HBO Go is working, run with it

Yeah, probably a little big current wise as well. They do make 8A also IIRC, but if you need an insulated package, then I guess the parts you guys have identified are the ones to go with. As for > .25W resistors, Mouser does stock Dale RN65 in a 178K, .5W, 350V. I couldn't find the schematic for that particular PSU either, but I only looked briefly.

I've never used their diodes, but just avoid their regulators. This is one I might think about using, unless someone sees something that doesn't meet the parameters required here. 512-RHRP30120

I also avoid ST Micro parts like the plaque. Had some negative regulators from them that didn't work right. National and On Semi parts worked just fine. Diodes I like Fairchild personally, depends on the individual rectifier diode I am looking for.

Happy belated Birthday!

Happy Birthday!

That was pretty much my understanding as well; the cable shield is part of the chassis ground, which may or may not be the same as signal ground. I also recall ground loop interupters, such is what is used on my headamp Gilmore refererence board. Basically a low value resistor (4.7 ohms?) and a cap, tieing board ground to chassis. I don't see this done much anymore, unless I haven't been paying attention. GND LOOP CAPACITOR 1 DIGIKEY EF4104 GND LOOP RESISTOR 1 MOUSER 280-CR5-4.7 EDIT: probably shouldn't have made the topic so cryptic

Yeah, those. From the Neutrik description: Wired according to IEC 268-12: Pin 2: signal Pin 1 and 3: connected to ground

Does the Hosa RCA/XLR adapter short the L/R - signals to ground? On a differential input, those need to be grounded when going SE. I know Kevin recommended the Neutrik adapters for the multiamp, which do this.

Mine might even be the prior gen.; refurb from Apple store. No issues in 2 years?

the older one isn't?

Yet Another XLR Question... Building my first balanced amp, some connection questions: What do you do with the shield? Reading the RANE app notes seems not appropriate for parts of this, since I am using 4-pin XLR, and the 3-pin standard has pin 1 as ground. I am reworking the previous 4-conductore rewiring my phones right now, and chopped the previously wired 1/4" plug cable part way to wire in a 4-pin female/4-pin male (the male will be the main phone connector into a 4-pin female on the amp), turning this cable portion into an adapter for when I want to use the phones from an SE amp. The main cable terminates at the phones in a 4-pin mini XLR, in which the shield is not terminated. I assume use the telescoping shield philosophy and terminate the shield to the connector body on both std. 4-pin XLRs at the mid point? For 3-pin XLR balanced amp inputs, just follow the RANE notes? Describe how YOU did things Also, on the balanced Dynahi SS thread, I see one amp using a male 4 pin XLR for the jack? Seems like a bad idea, and that the standard is (or should be), Male for inputs, Female for outputs?

Happy Birthday Doug!

Some people claim they can hear servos. I'm not one of them. Since they normally operate well below 1Hz, and having the servo can protect you from bad things happening, I see no downside to using it, even if the circuit is stable without it.

Happy Birthday Doug!

The LSK389 is an N-channel device while the SJ devices are P-channel. Here is a thread on diyaudio discussing at least the 2SK147 compared to the 2SK389 / 2SK170, etc. http://www.diyaudio.com/forums/solid-state/23954-2sk170bl-2sk369-mc-stage.html

I think most people are using the ON Semi parts. They released an EOL notice last fall that apparently their Korean packaging subcontractor would no longer do TO92s . Mouser still has some in stock, so I'd buy what you think you will need now.

Probable stupid question time: I was playing around with board #1 and ran a test signal into it using a Discman (SE, I- tied to gnd). On the outputs, I was seeing 2 signals (O+ and O-) that were each around 2.5Vpp, 180 degrees out of phase. The input signal was from the line out. With a gain of 6 in SE mode, I would have expected the output signals to be larger? Or do I need a load resistor across the outputs (O+ to O-)? Or is this potential loading of the input impedance? Gain resistors are the stock 5K and 25K. This is the first time for me playing around with balanced signals also.