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

[druu]

Also still waiting for tube adapters and DOA's.

 

[DIY-solder]

I have a few questions:

ATT/REL  which direction is FASTER preset?

HPF  middle toggle position is NO HPF, right? What about the other 2?

 

[tazwolf]

Hi
just got my tube mount pcbs and opamp pcbs here in Sweden (the mounts and opamp pcb fell out of the envelope when it split on its way).
Just a question there is no connection to the heater pins on the tube socket pcbs and I cannot see in the manual that we are supposed to
wire them manually, are we supposed to wire the heaters manually, or have I misunderstood something?

Regards
/Taz

 

[anvl]

If I remember well, attack and release controls are slower in clockwise.  And also HPF positions are "no hpf" left, de-esser middle and "200Hz" right.  I will check.

 

[Jeremy.Starseed]

A few details to aid in the design of front panels would be appreciated, I'm certain.

Here's where I'm at so far. Attack & Release times as well as the aforementioned hpf switch orientation is what I personally require.

Finally found the build manual and gave it a quick read. Bravo, well done! Muchly appreciated!

 

[shot]

Just got replacement tube mount pcbs!
Thanks Abe!

 

[taliska]

Hey all,

A while back I was obsessing over the various power transformer options for EU builders and reached the conclusion that EU builders can't finish the build in anything less than 2U. This is because the required power transformer options for EU builders won't fit inside collectivecase's PRR 176 case which is 1U.

Anyway, I was just having another think about things as I'd like to actually get this thing built soon, and I realised that I could just build the power pcb +  transformer in a separate case? Perhaps one of the little microphone power supply cases that everyone uses?

Obviously, a nine pin connector of some sort would have to be used, and I'd have to find a way to adapt the IEC cutout in the case for the nine pin connector, but I feel like it could be a good solution that would allow us EU guys to fit in the standard 1U case. Also would reduce noise for those who are using edcors I guess? (not an issue for me as I'm using Lundahls).

Thoughts? Issues? Can anyone point me to a suitable nine pin connector on mouser?

<edit>
Well...to answer my own question: there are amphenol mil spec connectors that could do the job, but they're not cheap and those plus the external case end up expensive enough that it's worth getting a custom case done instead.

I did a test layout in my G9 case that is in progress, which I believe is deeper than the cc PRR 176 case, and TBH I couldn't see a way to fit two transformers layed out flat and side by side. If a 2U case is used then obviously they can be mounted to the side of the case, but that's quite a tight fit as well I think.

I'm now thinking that a deep 1U case should get the job done. Modushop does a 350mm deep case (my G9 is about 250mm which comes out greater than 9" which is the depth of the PRR 176 case) and all of the transformers should have a diameter less than 100mm so that should be enough room.

Generic cases (apparently some customisation is possible with dxf files):

http://www.modushop.biz/ecommerce/cat038_l2.php?n=1

In the other PRR 176 thread, Kingston mentioned some transformers to use for the gyraf trick, both from here:

http://www.rapidonline.com/electrical-power/115-230v-toroidal-transformers-dual-primary-82719

And he said in his original message:

You need two transformers, widely available all over the place: one roughly 50VA 2X24VAC (or perhaps 18-24VAC) and another with maybe 5-10VA 2X15 (or maybe 12VAC).

Then I guess I'm going to have to get a front panel made from here:

http://www.frontpanels.de

Does anyone have a 1U layout/fpd file I could use as a starting point?

</edit>
Cheers,

Kaz

P.S. My tube mounts arrived as well! Thanks Abe!

 

[abechap024]

Well the heat sinks solved the 12.6V rail dying...Put one on another 317 i had around but it went as soon as I hooked it to the main board as well. That there power supply gets reeeaaal warm.  Definitely get beefy heat sinks for all your regs. Gonna have to wait for the higher voltage rated 317s from Digikey.

Under load my 100V rail has dropped from 110 to 74V.  I'm up to 3k3 3W resistors to get it down to 110V before it's hooked to the board ( I originally wanted to get all the voltages in line before doing that) but what conditions should the 100V rail be measured under?  Should I just go back to 1K and see if it's closer to 100V when hooked to the main board? I think it was about 136V before I started upping the resistor values...which means I dropped it 26V. Which is exactly what it is below 100V when actually feeding the main board...

I don't think this has been discussed, I have been following this thread post by post for 5 months though so I MAY HAVE MISSED SOMETHING.

Yes use heat sinks. Also you might not be doing the regulators any favors by turning the voltage down, that just creates more current they have to drop, as depending on what voltage power transformer you use there is a fair amount to drop. I use heatsinks on mine and they are ok. But I'm not going crazy with discrete opamps either...BUT you could probably get away with a dual 12V transformer if it was hefty enough, for the heaters and +/- regulators.

Also LM350 is drop in replacement for LM317 and LM333 drop in replacement for LM337 both have double the current capacity...so maybe a good idea if you are planning on using a lot of discrete chips..

 

[Sylvain D.]

Hi all,

Don't know if I missed it, but I have'nt found exact dimensions of the boards anywhere.
It would be helpfull in chosing a case.

 

[muffy1975]

Also,

am i right in thinking that,

if you have a 2u case, you can use the original messed up tube/valve pcbs. They connect with the tube/valve facing upright? vertically??

Or is this a problem too?

Michael

 

[berkleystudios]

Also,

am i right in thinking that,

if you have a 2u case, you can use the original messed up tube/valve pcbs. They connect with the tube/valve facing upright? vertically??

Or is this a problem too?

Michael

yes it just make the tube vertical, the board works fine

 

[muffy1975]

Thanks Adam,
the only thing wrong must be the 100v rail.


maybe the reversed 6VA Tx is not enough.

I have had to swap all the resistors on the 100V rail to 47R. They were 1Ks in this position but i was loosing to much voltage.

Maybe 94V is not enough???

Is 94V loaded enough juice for valves?

 

[muffy1975]

Do the 1MA meter fully deflect without any sound and then reduce from full deflection when metering gain reduction?

My 1MA meters seem fully pegged. The trimmer brings this down very slightly

Also, the stereo link switch which disables the attack and release of channel two seems weird. It changes the threshold and sound.

That can't be right.

what to do????

Michael

 

[ding]

AFAIK stereo linking will change the compression/threshold. http://en.wikipedia.org/wiki/Dynamic_range_compression#Stereo_Linking How much is your sound changing? How did you end up soldering the tube pcbs? I'm thinking of doing mine upright as well. Got any pictures?

 

[muffy1975]

I did my mine upright using the legs of used capacitors ( cut ) as connectors covered in heat shrink.

There is only one way of doing it vertically.

I lined up the heater connections.

the rest i presume follow in order unless that tube pcb is a real disaster.


What about the meters??  Should they fully deflect with no signal??

My unit is  compressing fine i think.

i have matched tubes ( at least that is what i was told )

 

[ding]

no. maybe you have them wired in reverse?

 

[muffy1975]

Wow,

surely it would not work at all in reverse as the heaters would not be connected to the right pins.

Does 1 on the main pcb go to PIN 1 of the valve?

Michael

 

[muffy1975]

Pin 4 and pin 5 of the valve are the heaters right?

I've checked with Ave and I have the valves connected properly

Michael

 

[boneindian]

Well I still haven't gotten mine up and running but I wanted to share a couple issues I've had in the interest of gathering opinions and just continuing to lay some troubleshooting tracks in the thread.

Last week, after switching to the higher voltage spec'd regulators everything was up and on for awhile but I couldn't get audio past R5 R6 R59 and R60.  I figured maybe I had fried my 5532 or something with all of my power issues so I powered it down for the weekend since I had some 600 ohm T-pad attenuators on the way from Hairball anyway.  After getting those wired in I powered it up again yesterday hoping to get some sound moving through it but over the course of an hour my new HVT 337 and 317 both stopped passing voltage, first the positive then the negative rail.  I've ordered some lm350 and a comparable(?) negative regulator the LT1033 (The lm333 seems nearly impossible to procure stateside and does not look like a drop in replacement?)

My concern is that, on the side of my dead regulators that is getting the voltage from the transformer I'm reading around 40V and there is no regulator that can handle 3A of output current and also handle more than 35V of input voltage.  Is my reading just that high because it's not under load?  I'm also only using DOAs on the output stage right now so should the current draw really be frying my regs?  I had hoped to eventually have them on all or at least the input and output...

 

[muffy1975]

yeah this PSU is possibly not well designed.

My heatsinks are boiling, but they stay on. BOILING

I measure 60v before the rgs. How? I know. I must be referencing the wrong point. you must be too.

I'm using an 18 18v TX with 50VA.