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

[ilfungo]

"7) tried log or lin 10k pots on output the result is really the same... big changes only on last positions... with a rev log big changes only on first postitons?"

Yes and for me seems to work very well....

"Ilfungo, do you use 470R pads?"

Yes

"3) stereo link increases compression a lot! We can match unit with threshold trim,"

I would not be wrong but it seems that the problem is that even stereo threshold trimmer are linked ...
It also seems that the compressor becomes much faster (it is as if the two pots are in parallel by changing the value of the pot)
Maybe I said something stupid?

 

[mrdarwin]

for bypass: spdt bypass is wired with 3 wires. Identify which wire is connected to ground, it is the third, from left to right, and disconnect from spdt. the sidechain circuit is now open but not connected to ground when in bypass. I hope it's clear

you re right, stereo link sounds like attack and threshold "added"...so not very musical. I didnt have impression that threshold trimmer were linked...

"calibration": no 470r pads, 1khz 0dbu, input to middle, no stereo link, threshold to make unit 3dB compression. You can choose how your unit will react, hard or soft compression, with "relation" between input and threshold. .. I dont know if its clear ???
Tried several 6bc8, 0.1dB difference between two channel, keep this pair.

 

[ding]

On previous versions when you put it in stereo link only one side would control much of the parameters (attack,release). Maybe there is something going on with that in this revision. I believe that in this revision even when in stereo all controls function the same as in mono.

 

[ilfungo]

look at this


manley uses this for a greater simplicity in channel matching....

http://www.manley.com/tech_page.php?product_type=pro&product_code=mslc&tech_page=Special_T-Bar_Modification

 

[mrdarwin]

hell!!
hum is from toroidal transformer! have to mount it off rack....
Don Audio's transformer users, have you the same issue???

 

[ilfungo]

Hi mrdarwin
I've Don Audio toroidal and no problem with Lundhal
I think your problem comes from Edcore (poor shielding)

On rev 2 with Edcor I had same problem....

 

[mrdarwin]

You're certainly right...
a little by little, things become clear.
Did you test my bypass option?

 

[ilfungo]

Yes and work perfectly!!!
Thanks

 

[ding]

Can someone who has soldered the DOA's with dip-8 pins post a close up picture of how you soldered the pins on without getting in the way of the other components? Thanks. 

 

[ding]

hell!!
hum is from toroidal transformer! have to mount it off rack....
Don Audio's transformer users, have you the same issue???

you can try wrapping transformer in copper tape like reply #4 below.

http://groupdiy.com/index.php?topic=32024.0

 

[mrdarwin]

Can someone who has soldered the DOA's with dip-8 pins post a close up picture of how you soldered the pins on without getting in the way of the other components? Thanks. 

Are you talking about others discrete opamps, because abe's opamp don't need to be upside down... ?
If so, I can't help you, I use these.
Thanks for the idea! But copper foil are harder to find for me than building an external psu... is it working with aluminium foil?

 

[ding]

I was referring to Abe's DOA's but I just realized I can just pull out the pins from the black plastic and solder them individually. Is that how you did it? I have not fired mine up yet so I don't know if I will need it but copper tape can be found online pretty cheap.

 

[mrdarwin]

I use this:
http://fr.farnell.com/harwin/h3161-05/douille-ci-1-0mm-or/dp/149319
http://www.banzaimusic.com/Vogt-1364D-Z-100-pieces.html
1) solder socket
2) mount 6 pins
3) put doa pcb on pins
4) solder pins on doa pcb

you have to solder pins on doa pcb before solderr anything... that's like I do.
anyone with a better technic?

 

[ding]

Abe was saying to just use the dip-8 footprint instead of the discrete footprint. I was just curious if anyone has gone that route and would share some pics.

 

[e.oelberg]

yes me, but I soldered the dip 8 first.
If I would do it again. I'd do the resistors in the middle first, than the dip8 and than the rest

 

[ding]

yes me, but I soldered the dip 8 first.
If I would do it again. I'd do the resistors in the middle first, than the dip8 and than the rest

Did you pull the pins out of the black plastic or did you leave the plastic on them? Can you post a quick image? Thanks.

 

[ilfungo]

Hi
I've a strange problem:
R channel Vu meter is reading correct
L channel vu is out of abiut 1.5 db
I've tried series and parallel trimmer but didn't work
Suggestions?
Thanks

 

[e.oelberg]

I left it in the plastic. I got the golden round ones, they just fit perfect

 

[abechap024]

hi Guys,
Working on the build manual but thought I would quickly address the stereo link option. The way originally specified in the wiring picture is sub optimal. There will be 2 different stereo linking options to choose from. This being the 1st one. This keeps both att/release controls active and sums the information of both channels via the dc control voltage. The second option will be ala Rev 1 and Rev 2 which only the left channels control the att/release which makes it a breeze for stereo matching but they both have pros and cons. Will have more info as I do more testing. Here is the option 1:

Notice that the right channels 2 stereo link pads are always bridged.

 

[abechap024]

Abe was saying to just use the dip-8 footprint instead of the discrete footprint. I was just curious if anyone has gone that route and would share some pics.

You solder the pins on the bottom of the pcb...so you don't need to clear any parts..I know you probably realize that but just wanted to throw that out there...