A New Take on the Classic Pass Labs D1 with an ESS Dac

[NicMac]

Ok. so like for the v-reg's we have a floating ground for the caps. Then we only have to deal with the difference between rectified DC and 45V adjusted. A 35V rating should do the job and I will use some 35V/2200uF Pana Fc that I already have. For the digital rail I have some 25V/2200uf Pana AM that should do fine.
I hope I will not pick up some real ground somewhere....... it would make a lot of smoke !!!
b.t.w. does the fet's and power resistors (Caddoc's) have to be isolated (electrically) from the chassis?
Thanks,
Nic

[opc]

Hi Guys,

I've been feeling a little under the weather today, so I haven't been on, but I just caught some of the capacitor talk.

All those electrolytic caps are indeed subject to high voltage, so you do need to use the proper voltage for them.

C1, C2, C4, C5 need to be 63VDC minimum or possibly higher depending on your transformer selection and line voltage. I'm using the 40VAC Antek transformers which gives me about 51VDC before the regs, so 63VDC caps are more than enough. I'm using Nichicon 63V, 2200uF PW series because they're very good caps.

C23, C24, C26, C27 need to be rated at whatever you decide to run your rails at. I would suggest using the same 63V parts here since 50V caps would be cutting it very close. Again, I'm using the same Nichicons as above.

The output coupling caps C28, C29, C51, C52 need to be rated for at least 35VDC.

There seems to be some confusion about floating grounds with the regs, but this circuit is no different than any standard regulator circuit. The ground is not floating, it's just run in a dual mono manner to prevent hum and ground loops. All grounds are tied together at the pins of the Buffalo.

If we look at the regulator, things will maybe make a little more sense. The input pin of the reg is at 51VDC, The adjust pin is around 44VDC and the output pin is at 45VDC. There's no more than a 7V differential on the regulator because no part of it is actually connected to ground. The caps on the other hand are definitely tied to ground! Every cap in that circuit sees at least 44VDC, so it's very important to use an adequate voltage rating.

I hope nobody has blown anything up!

As for isolation on the heatsink, most of the resistors are already isolated, but the fets absolutely need to be isolated with proper pads or mica. The absolute best thing to use here would be a slightly thicker thermal pad. It would allow for some wiggle room in the height of the parts and still give good conductivity.

res07njc:

I don't see any reason you couldn't do this, as long as you can find room to jimmy it all in. They will all need to be isolated though, but this applies to the on-board sinks as well.

I think I'll probably write up a little document when I get a few minutes of some of the key points during assembly. It might help avoid confusion in the future.

Cheers,
Owen

[qusp]

ermm but the regulators are floating, they do not have a ground reference, how can they be anything but floating? I admit I havent even been looking at the regulator circuit, so i'll just buy out of giving any advice, because I do not plan on using it either. if they had a ground reference they would die in this circuit. I did mean to specify 1000/50 regardless though, but probably best at 63.

OMG owen, sorry man thats terrible, note to self, never give out advice other than from or to do with personal experience on a forum at 4am, I was taking this as a floating bridge circuit due to all the talk of a floating supply earlier in the thread. very sorry guys, hope everything is OK. have printed everything out including the PSU circuit now

[flocchini]

Originally Posted by qusp

oh and yeah this



**** I hadnt thought of that...... best match highest gm quads are for myself and Flocchini, you guys really oughta thank this man too for making this all possible. it was just a fleeting idea I had and was hesitating about, until he offered to buy some and send them over. so I will either be thanking him for the angels coming down to my listening room from above and visiting upon me as I weep tears of joy, or cursing his name as I wake sweating in my bed, with nightmares of 5 decimal place LCDs 10 years from now

I hear the angels singing

[yoke]

Hi
Is there any chance for second GB ?
or is there any kit's left,as I would like to buy it. (haven't been around for some time so I miss this tread )

[qusp]

well only if there us enough interest and if opc is up for it, organizing things like this takes its toll. no boards left AFAIK all the no shows have been snapped up

[qusp]

Originally Posted by flocchini

I hear the angels singing

hehe we'll see

[opc]

Yoke,

I sent you a PM last night... check your messages.

Cheers,
Owen

[merlin el mago]

Owen,

You have PM

Cheers,
Felipe

[qusp]

anyone got any pics of the blank PCBs? comeon some eye candy. resistors are shipping today