PRR-176 REV 4 Build Thread ***Manual up!***1/16/14 - (chk 1st post)
- Thread starter abechap024
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abechap024
Well-known member
ilfungo said:Hi Abe!!!
I've wired the stereo link in old way and all is much better
The channels are anyway better in mono mode.
It's possible to use something other tube best matched like JJ6386?
thanks
Im not sure how to best match them, I guess just by buying a lot. As far as I know only the 6bc8 tube works and its substitutes...6bz8 etc...good thing is these tubes are fairly cheap!
Esoterimix
Well-known member
Hey guys, I need someone to make a quick clarification.... In the stereo linking image Abe posted, it says to link the "CW" on both the attach and release on the right channel.
- What does CW stand for? the only references I've found in general electronic terms have to do with clockwise or counter-clockwise... But, for some reason, I get the feeling it was intended to mean wiper...
Also, I managed to short the AC input at the IEC connector.... After I reset the circuit breaker and went back to testing, it seemed that the toroid has the proper output into the PSU... However, I'm getting absolutely no control of the voltages at the power rail section. I'm assuming I need to replace the regulators but I figured I would at least make sure there isn't something I'm missing. Fuse is good, tried turning the variable resistors as well.... Even the 100V rail isn't giving me anything once it enters the PSU - haven't had time to figure out where it stops. Any input would be great. Thanks guys...
- What does CW stand for? the only references I've found in general electronic terms have to do with clockwise or counter-clockwise... But, for some reason, I get the feeling it was intended to mean wiper...
Also, I managed to short the AC input at the IEC connector.... After I reset the circuit breaker and went back to testing, it seemed that the toroid has the proper output into the PSU... However, I'm getting absolutely no control of the voltages at the power rail section. I'm assuming I need to replace the regulators but I figured I would at least make sure there isn't something I'm missing. Fuse is good, tried turning the variable resistors as well.... Even the 100V rail isn't giving me anything once it enters the PSU - haven't had time to figure out where it stops. Any input would be great. Thanks guys...
ding
Well-known member
Looking forward to the updated build guide to get this thing started. Any idea how soon we can expect it? ;D
berkleystudios
Well-known member
CW stands for "clockwise", regarding the way the pot rotates, the opposite would be CCW or "counter clockwise"Esoterimix said:
regulators may be bad, would also check diode orientation and make sure they are correct
been super busy so I havent made much headway on this project. but I finally got my Orion 32 8) 8) hope to start working on this again soon
boneindian
Well-known member
Hey Abe, any word on those replacement tube pcbs? Deciding whether to drill and mount the tubes on the back of my chassis with wires running to the board in the correct order or hold tight and wait for the new boards I can slap my pc mount sockets on...
druu
Well-known member
Also waiting for replacement tube pcb's and missing DOA's.
abechap024
Well-known member
Yep got them. I will be shipping them out 
Thanks!
Thanks!ding
Well-known member
Finally started on this build!!!! ;D Abe, is a build butler coming soon for this project? It sure is a pain in the butt to find the components in this project. Would love to have a build butler so my eyes would stop crossing trying to read those tiny letters.
boneindian
Well-known member
Could anyone shed any light on exactly how to wire the meters and their LEDs off of the board? There's three connections: G (presumably ground) LED and M+. Are Ground and LED for the positive and negative terminals of the lamp respectively? and M+ goes to the meter itself? It looks like the 18V rail is feeding one of them in the schematic but it seems reversed from the physical layout on the PCB. I have yet to power mine up and I'm trying to figure out what I might need in terms of voltage drop resistors for the lamps. From perusing previous revision threads it seems there wasn't a dedicated LED feed and the lamps were advised to be wired in series...
Hi everyone.
My 176 is working !!! Really beautiful sound, nice compresion. I use two Lundahl transformers in each channel.
I used 470R pads, opamp input option, opamp output option. I use two power transformer for 220Vac. I made both transformers jumpers as shown in Abe's PDF and prh told us. By now, I only calibrate 0dB for meter. I haven't tried link options yet.
At the beginning, tried with ICs in everywhere and checked everything worked. Later, I changed to gar2520 discrete opamp in the first and the last, as Abe told us, leaving 22p caps. The unit sounds even better. Important: I found clearly that there is less distorsion with discrete opamps, much better option.
Thanks to everybody, it is really useful everyone's experience to reach my unit finished.
My 176 is working !!! Really beautiful sound, nice compresion. I use two Lundahl transformers in each channel.
I used 470R pads, opamp input option, opamp output option. I use two power transformer for 220Vac. I made both transformers jumpers as shown in Abe's PDF and prh told us. By now, I only calibrate 0dB for meter. I haven't tried link options yet.
At the beginning, tried with ICs in everywhere and checked everything worked. Later, I changed to gar2520 discrete opamp in the first and the last, as Abe told us, leaving 22p caps. The unit sounds even better. Important: I found clearly that there is less distorsion with discrete opamps, much better option.
Thanks to everybody, it is really useful everyone's experience to reach my unit finished.
boneindian
Well-known member
Having a bit of confusion as to the 120VAC input on the power supply. Of course a dual primary dual secondary 120V/18V transformer like this one
http://www.mouser.com/Search/ProductDetail.aspx?R=VPT36-1390virtualkey55310000virtualkey553-VPT36-1390
which looks just like the one in the wiring diagram only puts out 18V through each of the secondaries. And, although there are four primary wires obviously they need to be jumpered together for parallel operation. How exactly is one supposed to run 120VAC to the board using the type of transformer specified in the BOM? Maybe i'm just not understanding this on a basic level but I'm stumped.
http://www.mouser.com/Search/ProductDetail.aspx?R=VPT36-1390virtualkey55310000virtualkey553-VPT36-1390
which looks just like the one in the wiring diagram only puts out 18V through each of the secondaries. And, although there are four primary wires obviously they need to be jumpered together for parallel operation. How exactly is one supposed to run 120VAC to the board using the type of transformer specified in the BOM? Maybe i'm just not understanding this on a basic level but I'm stumped.
ding
Well-known member
Not to sound too obvious but it is right in the wiring guide. Wire it just like it says. Abe knows what he is talking about.
abechap024 said:
Hi Abe,
where is there THE updated build manual with ALL the errors and corrections for this revsion?
the current build docs for the REV 4 boards aren't complete.
I need to know where all the correct jumpers are meant to go before I switch the damn thing on.
what is the lundahl error written about in the above quote? What is the fix?
Also, can you post a picture of how to connect two transformers in the GYRAFF style for this pSU. I don't want to buy the don audio one!
ding
Well-known member
boneindian said:
I guess I should try to explain better in my own limited way. As far as I understand, the windings do not know if they are primary or secondary. You can use the second primary as a secondary to get 120v. It is not the safest method in the world but if your grounding is good and a fuse is used then it's not the end of the world. From what I understand you will loose half the power so in that transformer you linked to instead of being 18v at 2.something va it will be 18v at 1.something va. Someone with more knowledge can correct me. But that's what Abe is doing here for us in the US. If you are in another part of the world than this is a no go.
boneindian
Well-known member
Hey ding, I did wire it as in the guide but wasn't receiving power on the secondaries or the second set of primaries. When looking at the data sheet for the power trafo it says that, for parallel 120V operation
Parallel – BLUE and BROWN, Jumper BLUE to VIOLET, GRAY to BROWN
This may indicate an ignorance my part of the operation of multiple winding transformers...but that doesn't seem to jibe with what you are suggesting?
Parallel – BLUE and BROWN, Jumper BLUE to VIOLET, GRAY to BROWN
This may indicate an ignorance my part of the operation of multiple winding transformers...but that doesn't seem to jibe with what you are suggesting?
ding
Well-known member
I don't really know what to say. I bought this very same transformer because people building rev1 boards where using this transformer to do exactly that. I haven't got that far yet so I can't speak from experience with this project but if you read thru the rev 1 thread the info is clear.
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