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

[tazwolf]

mr Oelberg, you wouldn't have to have a wiring diagram available for that would you ?
I would like to do the same, in so much as I would like, switch down normal, middle- thru circuit but side chain disabled , up - true bypass (with additional relay bypass circuits boards of course).
I was thinking of using a triple throw double pole switch like this - dptt

http://www.seymourduncan.com/blog/the-tone-garage/guitar-wiring-explored-switches-part-3/
was this how you were planning to do it?

/Taz

here is a front panel... in case you like to modify it for your own needs.

my box is going to have a switch for sc bypass and hard (relay based) bypass

send me pm if you lke to get the fpd file

 

[ding]

If anyone finds it useful, here's a Mouser cart for the parts for the 6 DOAs using Abe's PCBs:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b36f41ddbf

I am not including:
2 matched BC550s per DOA
Millmax pins
You can get those from Classic API. I'm using the 2503 output transformers so just getting those from Classic API.

Let me know if I missed something!

Which one are the input transistors that are supposed to be matched? I'm still confused about that. I know its Q1,Q2 but I'm still not too sure where they go.

 

[kakumei47]

If anyone finds it useful, here's a Mouser cart for the parts for the 6 DOAs using Abe's PCBs:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b36f41ddbf

I am not including:
2 matched BC550s per DOA
Millmax pins
You can get those from Classic API. I'm using the 2503 output transformers so just getting those from Classic API.

Let me know if I missed something!

Which one are the input transistors that are supposed to be matched? I'm still confused about that. I know its Q1,Q2 but I'm still not too sure where they go.

I have to check looking at the boards and the schematic, but pretty sure it'll be the two closest to the input pins (the side with two millmax pins), near the 150k resistor

 

[ding]

Do you mean 1 & 3 on my image that I just put up? Can anyone else confirm?

 

[prh]

From a quick check with a continuity meter, I believe that Q1 is 1 on your diagram, Q2 is 3.

 

[ilfungo]

Is sufficient Hfe matching?
another question:
For Hi-pass filter selection, I've bought on/off/on switch
go well?
I've read in forum, use on/on/on.... ???
Thanks

 

[kakumei47]

From a quick check with a continuity meter, I believe that Q1 is 1 on your diagram, Q2 is 3.

That's what I'm seeing as well now that I'm looking at the circuit board. So 1 and 3 in your diagram. Use a small tip for your iron and be careful. Some close points you could easily bridge by accident.

 

[berkleystudios]

abe how can I modify the compression ratio for this build? ie. make it go from whatever the stock compression ratio is to more of a limiter?

 

[abechap024]

abe how can I modify the compression ratio for this build? ie. make it go from whatever the stock compression ratio is to more of a limiter?

I don't really know. I know that it is a vari-mu and they have a very soft-knee, as in the harder you hit it, the more "ratio" you have. Me personally find no need for a ratio, if I want to be gentle stay in the 1-5db GR range, if I want to limit and smash things I hit it harder....very natural and smooth...maybe try it out and go from there?


also:
I would be interested as well, not necessarily to implement it but just to see. I know the 175? had a ratio feature and I believe it did this by essentially changing the threshold?ie just sending more gain to the sidechain. I'm not sure, I'll have to dig up the schematic. You might want to mount the threshold knob of the front of your case, cause messing with that it certainly feels like it controls some sort of rationess. (along with the level/distoriton ect ect..)

 

[abechap024]

Is sufficient Hfe matching?
another question:
For Hi-pass filter selection, I've bought on/off/on switch
go well?
I've read in forum, use on/on/on.... ???
Thanks

Yes HFE matching is good. With the swith, you want the center position not to connect anything.

 

[ding]

Is sufficient Hfe matching?
another question:
For Hi-pass filter selection, I've bought on/off/on switch
go well?
I've read in forum, use on/on/on.... ???
Thanks

Yes HFE matching is good. With the swith, you want the center position not to connect anything.

I have a multi meter that supports hFE and that is what I am planning to do. At $0.14 I would wager I can buy enough BC550's to make it worth my while. At $5 a matched pair from CAPI I think I will take my chances and do it myself. I think buying 100 at $6 would be enough to find 6 matching pairs. I guess I will find out.  My concern is this...
"...if you want to be precise you should measure under the circumstances the transistor will see in his working environment." but I am going to chance it and measure them cold.

 

[berkleystudios]

Is sufficient Hfe matching?
another question:
For Hi-pass filter selection, I've bought on/off/on switch
go well?
I've read in forum, use on/on/on.... ???
Thanks

Yes HFE matching is good. With the swith, you want the center position not to connect anything.

I have a multi meter that supports hFE and that is what I am planning to do. At $0.14 I would wager I can buy enough BC550's to make it worth my while. At $5 a matched pair from CAPI I think I will take my chances and do it myself. I think buying 100 at $6 would be enough to find 6 matching pairs. I guess I will find out.  My concern is this...
"...if you want to be precise you should measure under the circumstances the transistor will see in his working environment." but I am going to chance it and measure them cold.

I bought 100 and had dozens of matches very quickly

 

[berkleystudios]

abe how can I modify the compression ratio for this build? ie. make it go from whatever the stock compression ratio is to more of a limiter?

You might want to mount the threshold knob of the front of your case, cause messing with that it certainly feels like it controls some sort of rationess. (along with the level/distoriton ect ect..)

was already planning on it

 

[abechap024]

Yea, matching is sorta therapeutic too. I just measure them cold also, but I figure if they are all cold they should measure the same right? I've heard people get very technical with how they measure them...as far as having a fan blow or not holding them for too long. But I've found at least in practice doesn't seem to matter that much.

Also I've also heard that you really don't even have to be THAT critical when you match them, I still match mine, but I guess its not *that* important in actual operation. I've never done any tests though.

 

[abechap024]

Also as far as millamax pins for the opamps, if you are using them with the PRR you might as well get some bulk headers and dip-8 sockets off ebay for a fraction of what you would pay for millamax pins...and they will work great. Just a thought, have extra money to go twards cool knobs or something 8) 8)

 

[e.oelberg]

I'm about to start my first test procedures: PSU

what kind of fuse did you choose 220V 160ma=35W or 200ma=45w ?

nicholas

 

[prh]

What is the purpose of the 1k Trim (R50 / R103) marked Output Sym?

I'm also a bit confused about the input set-up - options and jumpers, etc.  Would someone please clarify? 

 

[e.oelberg]

mr Oelberg, you wouldn't have to have a wiring diagram available for that would you ?

here is a front panel... in case you like to modify it for your own needs.

my box is going to have a switch for sc bypass and hard (relay based) bypass

send me pm if you lke to get the fpd file

.

Not yet. But it should be simple. Question is where to get rhe 12 volt for relay switching. I guess i tap the heater supply

 

[ding]

What is everyone using as a dip8 header for the DOA's that doesn't block the other components? It seems like all the ones I find cover the other component holes some how.

 

[abechap024]

What is everyone using as a dip8 header for the DOA's that doesn't block the other components? It seems like all the ones I find cover the other component holes some how.

Just ones like these:

http://www.ebay.com/itm/10x-10pcs-40-Pin-Male-Header-0-1-2-54mm-Tin-Square-Breadboard-Ships-From-USA-/230975161558?pt=LH_DefaultDomain_0&hash=item35c73144d6

I just solder everything else and do those last...seems to work fine for me.