jwzhan

no extra windings. just two secondary windings with 72VCT @ 2A each. Even if you want to have the lower voltage rail to work for the digital attenuator, you should have it in another transfo, because you need to have the controller module on 24/7 for it to remember your settings, so the transfo for those rails should be separated from the transfo that provides power to the amp. You don't want to turn-off the controller with the amp and come back to find that all your settings are restored to default because the cap that's sipposed to be providing power to memorize the settings ran out of juice. If you are not using a digital attenuator... just leave the lower voltage section unpopulated and save some money.

transfo for Dynahi is as I described. 160VA for two amp boards are fine... as long as you only drive headphones. I would still use the one I said earlier. 72VCT@2A (148VA) per channel... Make it a two windings in one or just get a 72VCT@4A and it shouldn't cost much more than a [email protected] transfo if you are getting a custom one. overkill is always good. I think Kevin mentioned some where in the dynalo project page that the opamp is only able to offset something like 10%.. so some careful parts matching are definatedly needed. EDIT: to be more precise.. a transformer with 2 x 72VCT @ 2A (or 1 x 72VCT @ 4A) for the entire balanced dynahi amp is recommended.

oh sorry man... I was talking the Dynahi PSU.. because this is the dynahi build thread, so I assumed... forgot that you are building the KGSSHV (or are you building both at the same time?) One PSU board for both channel in KGSSHV's case. Those specs for the KGSSHV transformer are fine. You can up the output current for the HV winding to... say 200mA (instead of 125mA,) and raise the output current of the amp. This will add some heat, but should make the amp sound even better. Extra heat should be no problem with off-board version, because those heatsinks are way overkill. (mine runs at sub 40C level with default current output) But don't do it if you are building the on-board version, because that runs plenty hot with default output. John raised the output current and he is very satisfied. Details are in the KGSSHV thread.

72VCT@2A per channel. Better to use two PSUs if you intend to push the amp board to the limit, so you will need two separate windings in that case.

bdent is a mess right now. Search function is only half working (and that may be overrated,) so I wouldn't trust the result. If you really want to know... get a rep, ask him in person, and hopefully their inventory system is not as screwed up as their website.

I have some 2sj74 and 2sk170, but they are only matched pairs not quads.

855-C90-3102R14S-6S 855-C90-3106F14S-6P amphenol connectors are great, but the plugs for cable are just insanely expensive, often more than $100 each. Harwin will work just as good. Also, you should use female chassis mount for PSU; not that it really matters, because it's not HV, but it doesn't hurt.

Definately two 2U400mm cases. I decided to go full out and to use KG attenuator+LCDuino. I think this will be THE dynamic amp I will have, so heck, why not.

Thanks for the answer! I did miss the info on page 3 about the omitting of 15V regulators. I'm going with 445 then. The cost for the amp is rising very fast... and has already exceeded the cost of KGSSHV, which I didn't expect; but I'm sure it will all be worth the money and effort at the end, when it makes music.

I did some adjustment to the dynahi amp and PSU BOM. I'll make more adjustments as I finish stuffing the board. I'm wondering the difference between OPA445 and OPA27 as servo. I know the spec differences, but do these differences make one better than the other as servo?

I also have a somewhat updated BOM based on lil knight's. I have not finished stuffing the boards, so I don't know if there are more wrong parts or missing parts in it.

wtf

Happy Birthday!

Definately interested if it can out perform all the stax amps currently in production (which I'm sure it will.)

Mouser will have 3000+ 4170G in a week, so you can order it right now and just wait for it. Didn't check digikey.

the longer version (4170G) should be fine. I'm using it, and it's just as good.

Thanks for the answer! Great. Heat is not such a big prblem after all then. Maybe I should build an on-board one just like eggil to save some space...

just don't get the Fluke's base model, because those meters' input impedance is too damn low. I have a cheap $50 Weller station.. it doesn't have enough juice for soldering heatsinks from time to time, but other than that it served all my need.. A solder station with Temp feedback and control would be much nicer for a novice builder, because guess the best Temp for solder can be a little difficult...

Mine is off-board, same as your first one... so they should be very similar... I don't have a temp measuring tool, but it feels like some where between 60 and 70. Finger can only stay on there for like 2~3 sec. The covering plate right above those sinks are like 45 (very good hand warmer,) and the big sinks for the amp output devices are like 40 (can barely feel the heat with my hand.) I don't want to imagine having all those heat in one enclore with some vent holes and only a few on-board sinks for heat dissipation. I really can see the case itself getting very very warm to the touch, especially during summer... Can anyone with a finished on-board one case KGSSHV comment on it?

That's actually very cool for on-board. Were those measured with enclosed case or just open? Because the heatsink on PSU definately feels a lot hotter with the case enclosed... (that's without the amp output devices adding to it.)

those 4686 parts are gone already?! damn they went fast.... luckily I have enough of them as spares... and 2705 too? I barely have enough to build a balanced Dynahi.. need to stock pile all the parts I can get my hands on... this is just crazy..

Tran just did another board production, so he should have plenty for sale. very nice! definately takes up much less space than the off-board or two cases. Any comment on the temp of the heatsinks?

not really getting what you are saying about the cap and 20K, but I don't believe any wires are needed. The small pads above the caps are through plated so the top and bottom layers of traces can connect, and it should serve no other purposes. CCS choice has nothing to do with Global or Local feedback, so nothing needs to be changed. Just jump G or L (which ever you desire) to the center pad. Or use quick connect method, so you can switch between G and L if you so desire. Just wondering.. what benefit does the servo provide in this case? I'm sure off-board with servo is coming some time, because there are still plenty of unused space on the PCB to cram in additional circuit!

That clears everything up. I was just wondering what the L and G stood for. Thanks.

I just realized that there are some changes to the v0.6 board... Can someone explain to me what these changes are for?