PS help

[Blooze]

I've been playing around with PSUD a little trying to learn it and have this PSU design for a 5965 Darling amp I'm in the process of building. I have most everything except the iron. This is using a Hammond 270DAZ and I haven't been able to get the DCR for this from Hammond so it's just a guess. All the PS parts I put in because that is what I have. BTW, I also have another Hammond 158M choke, FWIW. If anyone could make a few suggestions I'd sure appreciate it.


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[EWBrown]

I think I have a 270DAZ at home, if I do, I'll check the DCR for you.

/ed B in NH

[Blooze]

That'd be great. I was thinking this trannie might work instead of the 270FX. The FX would be larger and the DAZ has the different mounting scheme, which might go better as far as asthetics on the Darling might go since all the tubes are small. Looks are a secondary concern at this point, but I always like to keep it in the back of my mind.

[EWBrown]

The Hammond 270DAX measures in at 156 ohms DCR, one side of CT is 76 ohms, the other side is 80 ohms (typical "unbalance" of layer-wound transformers). FWIW, the DCR of the primary is 3.5 ohms.

HV secondary is 260-0-260 @ 90 mA.

I have this transformer for a yet to be started "Univox 45" clone. 12AX7 and two 6BM8s.

/ed B in NH

[Blooze]

Thanks!

When I plug the DCR into the equation the B+ goes to heck. I'm gonna have to rework the design or go to a different trannie.

I really would like to use a CLC or CLCLC PS design with another RC going to the driver to lower the B+ to 250V from the 270V I need at the 1626 and to also smooth things a little more for the driver.

The choke in the design above I have two of and I have the 25uF motor runs, but have not got any of the other caps for the PS until I decide on a trannie.

Help?

[Shannon Parks]

Hi Blooze,

The 260VAC number you have plugged in at the power transformer is probably too low. I seem to recall that Duncan says to put the unloaded secondary VAC in that location which will be higher since there will be no voltage drop across the secondary's DCR. I would guess that rated current times half the DCR would give us the magic number: 90mA * 80 ohms = 7VAC, but lets just make it 270VAC. That should get you a little closer. You can also try different rectifiers in there, too.

Before you lose too much hope in the 270DAX, I think your simulations show you are close enough that you should do a mock up of it and see what you get. I think +/-5% your target voltage will be fine.

[Blooze]

I haven't given up on it, but I don't have a PT in my possesion yet. I'm trying to narrow down what I need balanced with the overall size of the amp before I drop the cash. The 270DAZ would go well as far as the size of the Darling amp goes as 1/2 of it will be under the chassis.

Also, I noticed the DAZ is a 117V trannie, so the output voltage should be a little higher as our wall AC tends to run a minimum of 121V.

Any suggestions would be most welcome!!!!

[Blooze]

Here's another PS design that my friend and I have been thinking about. Same chokes. Any comments or suggestions would be great. The power trannie in this version is a Hammond 273X.

[sorenj07]

:D I'm on to you
http://www.audioasylum.com/forums/tubed ... 11610.html
http://www.diyaudio.com/forums/showthre ... ost1050973

[Blooze]

Yep. I like to get multiple feedback on my questions about things as I try to learn. I find that most the forums have a handful of people that seem have extensive experience and can give me answers to my simple questions.