gepardcv

@kevin gilmore: I assume that a 2U chassis wouldn't provide enough heatsink area?

@tonyxu: Maybe try emailing Bottlehead? It’s local to you. Although it has in-house expertise to do the work, I doubt anyone there will take on this project. That said, the company has been around the Seattle area for many years and might share some contacts. Meanwhile, for safety, please unplug the amp and close the case. The voltages on some of the wires and traces inside are very dangerous (and who knows if that build is safely grounded at all).

Is that a stereo board? I'm trying to wrap my head around how to heatsink it properly.

I wonder if the Audeze-provided EQ is the one from Bob Katz's review of the CRBN (https://positive-feedback.com/reviews/hardware-reviews/audeze-crbn-electrostatic-headphones/ and https://positive-feedback.com/audio-discourse/audeze-crbn-headphones-part-two/). (Spoiler alert: he loves the CRBN, and his EQ is fairly mild.)

A demo tour would be amazing, though TBF it’s unlikely I will buy either.

I personally love the KGST. I haven't checked parts availability lately, though it used to be a reasonably affordable build. You can sometimes get a good deal on a 007 (I paid nowhere near list price for mine), though it definitely does not err towards brightness. Great headphone, though.

In what way?

I would appreciate a bit of advice with regard to mounting non-isolated active devices on heatsinks. While trying to get my feet wet with speaker amps, I bought a Gainclone kit (LM3886-based chipamp). The active devices included all require heatsink mounting, and all are non-isolated (LM3886T in particular instead of the isolated 3886TF). The kit does not include isolation pads, PEEK screws, shoulder washers, or any of the things we use here to attach high-voltage devices. I asked the vendor about this, and he said that I shouldn’t worry about it — he said that the tabs are grounded, and therefore do not need to be isolated from the chassis. I don’t understand this statement, and asked if “grounded” in this case means “the case is connected to safety earth on the inlet”, and if that implies that the amp cannot ever be connected to an outlet without a safety earth line (which I normally think of as necessary to protect against accidental shorts, but not as a hard requirement to prevent electrocution in everyday operation). He replied: “The power supply uses a UL Listed transformer, power entrance, fuse block, and power switch.” This does not sit well with me, but before I push back on the vendor, I thought I’d ask here if I’m just ignorant. Is there something about UL Listed hardware that prevents a high-voltage device which is electrically common with the amplifier case from shocking the user? Is there a grounding scheme that negates this danger?

Exciting! And that amp looks gorgeous. Please post some photos of the interior (if not sensitive, of course).

@Pars: I used an M6, countersunk, to mount an AS-0518 on a Modushop Galaxy 388 base panel, which I believe is thinner than 3mm (supposedly 2mm). Also used FPE and FrontDesign. It turned out fine and looks plenty sturdy to me. I don't think the trafo will fall out.

+/-20V. I should have been clearer.

Right. So with a GRLV destined to output 20V, what’s the right secondary size? 12/12 gives 24V, which I’m wondering if it’s too much. I’m sure 18/18 is too much. I used 22VCT before, which was perfect and ran cool.

I thought that tying two secondary windings together to make a center tap effectively creates a series AC circuit, which adds together the voltages of the windings. So two 12V secondary windings make a 24V center-tapped winding. And 18+18 would turn into 36-0-36, which definitely seems too high for a 20V DC output. Is that wrong?

Question about transformers. I have a GRLV I want to repurpose, and it’s been used with a 22VCT transformer (single bridge rectifier) which for various reasons can’t be reused. I want to use the GRLV now with an Antek dual secondary transformer. I don’t want to change the bridges on the GRLV because it’s one of the earlier PCB versions that has incorrectly sized holes on the rectifier pads and it’s annoying and messy to (un)solder all that. 1. Can I tie the secondaries together and achieve a center-tapped equivalent? This suggests that I can: https://electronics.stackexchange.com/a/571731/59134 2. There is no 11V dual secondary Antek product, but there’s a 12V (https://www.antekinc.com/as-0512-50va-12v-transformer/). This means it’ll be equivalent to 24VCT (if I understand things correctly). Is that okay for a 20V output GRLV, or too high? I guess I could spring for a custom 22VCT transformer, but Anteks are so much cheaper and more convenient to buy.