gepardcv

Clarification: I just observed the following: 1. With nothing connected, the relay clicks about 4-5 seconds after power on. Pins 3 on U1 and U2 show +13.2V before the click, and +12.8V after the click. The 500k resistor always shows -12V, and never flips. 2. With anything connected on the input side, the relay never clicks.

Yes, and here's something odd: I just powered up the amp with all inputs and outputs disconnected from the protect3 board, and the relay clicked. Maybe the board is fine, but I still have a wiring mistake somewhere and it causes a fault.

0.005 V (basically 0) on both pin 7 of U1 and pin 8 of U2. -12 V at the 500k resistor. I should just make another of these boards because this one is fried, yes?

I just tried adding this circuit to my in-progress supersymmetry Dynalo build. First few times I powered it up, I thought I heard the relay clicking, and there was sound on the output. Then the clicking stopped, and I don't get output anymore. The first few times I powered it up, I was fixing wiring mistakes with the amp boards, but I'm pretty sure they're fixed now. Question: is there a simple way to test if I fried the board? I don't see char marks anywhere. The amp boards seem to be fine, since I get sound when I wire their outputs directly to the headphone outputs.

Thanks! Got it. Next question: I brought up the linear power supply (a Bel Power Linear HAA15-0.8-AG), and I can hear a faint buzz from the transformer when it's on. I doubt it'll be audible once music plays, but still: is there anything I can do to reduce the noise?

I'm finally at the point of wiring the amp together, and want to clarify the correct way to handle grounding from the volume pot (I'm using the TKD 601 board to mount the volume pot). Do I run ground wires from the volume pot to the star ground (four in all), or from the volume pot to the amp boards, along with the + and - signal wires (and ignore the ground inputs on the amp boards)?

While we're on this subject, what is the correct wiring for 4-pin XLR headphone output jacks? I found this diagram: http://robrobinette.com/images/Audio/HiFiMAN_Pin_Diagram.gif So pin 1 is L+, 2 is L-, 3 is R+, and 4 is R-. So far so good. But compared to the HeadRoom two 3-pin XLR jack guide, there is no chassis ground. Why not? Am I missing something?

Pardon the ignorant question, but... does using this circuit make any sense with an electrostatic amp, like a KGSSHV or KGST?

I used to feel the same way about Gould's original recording of the Goldbergs. Then I discovered the Zenph re-performance release (see Amazon and HDTracks) — turns out, I just hated the shitty 1955 mono sound. Both the 1955 and 1981 recordings versions are beautiful, just very different. As a side note, when I do my unskilled best to play the Goldbergs, it's awfully hard to find my own sound and not fall into the trap of imitating Gould. PS: Sorry, I know this is totally off-topic on this thread.

Early version of what? The Goldberg Variations?

Damn it. I was planning to wait to get the 007Mk2.9 after I finally finish building the KGST. Now you're tempting me into placing a PJ order sooner rather than later.

Looking at MPSA56 parts on Mouser, and most are discontinued, just like MPSW. This is the only exception. Is that what you guys are using?

I don't have a spare set, but I'm in if there's another group buy. Especially if they're as nice as the previous run. 4oz copper, wasn't it?

Because PJ presumably gets its goods from a dealer in Japan with high inventory turnover?

What does everyone use to run wires along the amp chassis? I was thinking of clamps like these from Mouser, but am wondering if there is something neater. Maybe something with two eye holes instead of just one?

If anyone wants some recent KGSSHV boards, I have two extra sets for the on-board heatsink version. kgsshvamp14mini.zip and almost kgsshvpsminifinal.zip (except it's version 1.0, not 1.1 — I didn't check closely what changed here between the previous final version and the current final version ). Please PM me if you're interested.

I see, thanks, that's really helpful! What IEC inlet model is that? I don't think the ones I have been considering have ground-to-chassis connections through the case mounting screws.

Thanks. I'm trying to figure out the most elegant way to deal with the ground connection on my in-progress builds, and I like your breadboard setup. How did you connect the star ground terminal to the chassis? Just a wire and a locking nut? Did you use the inside rails on the Modushop case for it, or did you drill a separate hole? (A detailed photo would be much appreciated, too.)

So your star ground is the breadboard with terminals on the left?

Is that kgsshvpsminifinal.zip on Kevin's site?

Thanks! Is there any reason to use something like this slightly pricey Ohmite part (SM101031003FE) which seems like a perfect fit, rather than just bend the leads of an ordinary axial resistor for a vertical mount?

1. For the 100uF cap, I measured the leads at 2.5mm, and thought to use 647-UMA1E101MDD from Mouser. Is that adequate? 2. There are 7 short components on the board labeled "100k" left of the terminal blocks, but they don't look like normal resistor silkscreen images (2 by the in block, 3 by the out block, 1 to the right of each row of 1uF caps). Are they just resistors I'm supposed to mount at an angle so they fit?

Looks great! What PSU did you use? Is there any sign of the heatsink fins raising the temperature of the PSU or transformer?

I have some extra boards of http://gilmore.chem.northwestern.edu/boards/kgdynalobal5.zip if anyone needs them. This is the through-hole version of the Dynalo Mk2 which uses discontinued mpsw06 and mpsw56 parts (Mouser may still have some stock, I haven't checked lately).

While I wait for my boards and volume pots to arrive, another question occurred to me. What's the stock gain on this amp? I prefer low gain, since I don't listen to my music very loud, and I like to be able to plug in sensitive IEMs at my desk sometimes. What's the best way to adjust it down if it's relatively high?