Kerry

Really nice! What finish did you use on the face plate?

That really looks nice! Great work.

Yes. What Sam said

Nice Eggil. You could also consider putting in blind taps for the standoffs.

Nice

The resistors in the batteries were the ones that were leaking. Make sure whatever you use are well insulated and are lifted off of the board. I originally used the red PRP and had them lifted, but they still caused problems. EDIT: Looks nice so far

^Yes indeed. Enjoy

The Darlington pair should be high hfe. No need to match within the pair. That's all I can think of at the moment.

I'd go for the higher hfe and get them as close as you can.

That knob really does make that amp stand out

Welcome to a wonderful hobby and great community. We apologize in advance to your wallet

Really nice work Craig

Wow. Very nice! Can't wait for your impressions once you get it running.

Nice design Geoff. It really looks beautiful

I think it sounds better upside down I see you did a lot of work on the board since last night. I love it I noticed the serial interface for the drivers. That really simplifies the board. This will fit perfectly in my build.

I've done the test fit for the amp section as well. Here's a better approximation of what it will look like. From underneath (Excuse the mess of wires. I'll fix those up once I'm happy with the fit)... Here's a shot from the top of the amp... I've just been listening for the past hour. Sounds great EDIT: PS. Happy New Year!

Thanks - and yes it does sound great. Kevin - Are you thinking of doing two columns and continuing to use both sides? Could be interesting. It would be nice if it could be soldered by hand too. Maybe trim down the control area a bit too.

I finally got the HV caps and the PS up and running. The voltages look good including bias and pre-reg voltages. I mounted the transformer and board to a temporary wood cutout that I milled. Fit looks good. The wiring is nice and neat... Here you can see the transformer in the steel case mounted to top plate (wood for now)... So far so good

The nice thing with the maxim driver is that I can set all of the pins low/high with one set instruction. It is programmable via a 3 bit address. I'm using an expander to control the address and set/reset. I've designed it so I can control two drivers with one expander, so two expanders and 4 drivers per channel. I've been setting one relay at a time, which is the same as I was doing with the original boards. I think I can get each channel to about 4" x 1.5". I'd like to see them mount one to the other. If we offset the relays this should work fine. Total dimension for balanced would be about 4" x 1.5" x 1".

I used two pins per coil. Here's the tech note I followed: http://www.maximintegrated.com/en/app-notes/index.mvp/id/3288 That's a lot of T2's in the wild

It must nice to have a Birgir for that I've used these relays, G6KU-2F-Y-DC4.5, controlled by the MAX4821EUP in another project. Very simple circuit and works perfectly. The relays are much smaller than the original ones. Going to all SMD parts would help a bit as well.

I've decided I'm going to build a smaller version of Kevin's digital attenuator boards and add an MCU and small OLED display. I already provisioned the 5V on the PSU (instead of my original thought to do 12V). I've got a .333mA transformer and I'm trying to keep it all around 230mA, which I think I can do. I'm also going to add a USB DAC. I'm really liking what AMB is doing with the Zeta1. Since I want balanced output, I can't use the gamma 1.5. The gamma 3 is more than I need for this and much more than I could fit. I'll likely just keep it to USB (no SPDIF). I'm also likely going to use an ASRC (same from the Gamma2). I've already done this in another DAC. I'm also going to build in some isolation for the I2S and I2C (if I decide to go with software mode on the WM8741). I won't be able to cut dual mono not enough space or power. I had a very cool thought that I should also add a built in digital volt meter. Besides being very cool, this could help adjust the bias between the +/- for each channel. I've got a preliminary design and so far it seems to work in LTSpice. It'll have a range of +/-30V, which is more than I need. I'm going to go with a single knob/encoder with a momentary switch for volume control and to run through the menus.

I have some sc4686's that I was going to use but the hfe were 20 or less. The sc3675's that I used were 63. I wanted it to be higher so I went with the latter. I also have some 2sc3840's (I've used these before) that have a small exposed tab like the sa1486's. Might have been a better choice (pin out is reversed so you'd need to flip them). Nopants - I've seen you post these parts before. What is the part number. I don't mind being extra cautious. Edit: The FJPF2145 seems like a good choice.

It's .13" or 3.3mm. That should be plenty. Good guess Marc.

Here's what it will look like in the chassis. This is looking at it from the bottom of the amp.