PRR-176 REV 4 Build Thread ***Manual up!***1/16/14 - (chk 1st post)

[muffy1975]

But,

mine is up and running and sounds cool.

the link is daft however and I can't get my meters to work. they are fully deflected when there is  no signal??????

 

[prh]

I have the Don Audio transformer.

One of the 18V windings is 1.2A, the other 18V winding is 0.4A.

Is the 1.2A winding used for the tube heaters?

 

[muffy1975]

yes I believe so.

0.4 amps is about right for 8 Ic opamps.

 

[abechap024]

But,

mine is up and running and sounds cool.

the link is daft however and I can't get my meters to work. they are fully deflected when there is  no signal??????

They are supposed to be fully deflected (or at "0") and come down with compression.

Yes the power supply for the opamps and heaters, possibly a 12V power transformer is a better bet if you have too high voltage before the regulators. The power supply double the voltage for the opamps so it has enough juice to run the bipolar rails, so you want to have it under load to drop the voltage a bit.

 

[boneindian]

Hey abe could you share what power trafo you're using for the reference of us American builders?  Under load I'm at 49-50V before the regulator which means I'm dropping 33-34V to get it to 16V.  Most of the regulators are spec'd to drop a max of 35V so I'm right at the top tolerance but not over...I'd prefer to not have to get another toroidal but at 50ish Volts under load it does seem the power supply is nearly tripling the voltage as opposed to doubling it?

 

[boneindian]

I've also been working under the assumption that the power ins on the board can be used interchangeably...is this correct?  I'm going in through the OPT IN because my power supply board is to the left of the main board.

(The answer to this is yes, I don't know if I was feeling brain dead or lazy  but a continuity check cleared that right up)

 

[johnnyscotch]

I'm interested in sourcing a power trafo as well.

Will Gustav's work?
https://pcbgrinder.com/index.php?route=product/product&path=94_97&product_id=103

 

[shot]

I have one thing that confuses me when collecting parts for my build.

Since I'm in europe, I have 230 VAC lines.

If I get a transformer from Don Audio http://www.don-audio.com/prr-176-power-trafo-sec-18v-18v-120v
then I will have to go with 1K 2watt resistors on PSU, just like in regular BOM

Am I right that those 3K9 5W resistors noted for european buliders are only meant to be used with 230V primary to 230V secondary isolating transformer (1:1)?

 

[ilfungo]

Hi Shot
I've used Don Audio transformer ( I'm in Italy) and 2k2 3w resistor....
For me all is ok!
I don't have used DOA's but Ic's ( LM317-337 too much hot with DOA's)
Ciao!

 

[shot]

Ilfungo,

Huh, ok, thats new for me! 2K2 was never mentioned. But I trust you. I'll get those and see how it works.

Today I found out that a local manufacturer can make me identical torroids as those from Don Audio but for lower price so I'll get those. I hope it will work the same. Just in case I'll order both 2K2 and 1K to see how it performs. 2K2 will be my first try and hopefully it'll stay.

 

[johnnyscotch]

I'm interested in sourcing a power trafo as well.

Will Gustav's work?
https://pcbgrinder.com/index.php?route=product/product&path=94_97&product_id=103

 

[AntoineQ]

Hi,
I finished my unit, works fine and sounds good!
I used Don Audio transformer, 4 Abe's DOA and +/-18V regs (LM317/337) are getting very hot too.
So will a replacement by a LM350 and a LM318 solve this?

 

[Sylvain D.]

...and what about this one for 120ac mains?

http://www.digikey.ca/product-detail/en/VPT36-1390/237-1334-ND/2090072

Seems to do the gig...?

 

[berkleystudios]

Hi,
I finished my unit, works fine and sounds good!
I used Don Audio transformer, 4 Abe's DOA and +/-18V regs (LM317/337) are getting very hot too.
So will a replacement by a LM350 and a LM318 solve this?

That's a tastey build man! Wouldn't happen to have a mouser cart for those DOAs would ya?

 

[Sylvain D.]

Hey Adam,

If AntoineQ used the one a few pages back, here it is.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b36f41ddbf

I also suggest you checkout Abes' Build Buttler. You'll find a link  on the first post of this thread.

Cheers.

BTW AntoineQ, nice build!

 

[Sylvain D.]

AntoineQ,

Can I ask where your front pannel comes from?

 

[AntoineQ]

I didnt buy the DOAs parts on Mouser but on a german store which is cheaper (for Europe at least), I only bought BC550s matched pairs to Jeffrey from ClassicAPI.
For the front panel, I designed it and got it made from frontpanels.de

 

[Sylvain D.]

Understood.
Nice job!

 

[AntoineQ]

Here is my Front Panel Designer file (change .txt for .fpd) for the front panel if some are interested...

 

[AntoineQ]

and the vumeter scale reversed for Hairball 8027 ;-)