All things Green Pre

[Phrazemaster]

Success! 

I replaced all the components suggested on my PSU: the regulators and the bridge - and also reworked some wiring. Took me all night. I had previously failed to install insulators between my heatsinks and my regulators and *something* blew.

So, after replacing said components meticulously...it works!!!! Thanks Peter and Harpo for your suggestions; I'm burning in the PSU now just to make sure all is *reall* well but the output voltages are fine and the heatsinks are actually cooler...

So, thanks everyone!!

Mike

 

[sunyata]

Hi,
has anyone experimented with stacked op-amps?
I've tried it in guitar pedals, where the tone gets punchier/fatter.

/Lars

 

[Phrazemaster]

Hi gang, I want to get a scope but I know I'm not going to use it for much other than setting things like the green pre finalizations. I found a little tiny scope, at the link below. Would this work for testing/callibrating the green and possibly other audio projects? Or is this too insignificant a scope to bother with?

http://www.seeedstudio.com/depot/dso-nano-v2-p-681.html?cPath=174

Also it says it has a signal generator; any knowledge if this would suffice or would I still need another box for that as well? It looks like it only has a square wave; Peter's doc calls for a sine so I'm assuming I still need a signal generator.

Edit: I found this signal generator for a pretty good price on eBay; this should do the trick, right?

http://www.ebay.com/itm/2MHz-DDS-Signal-Generator-Sweep-Function-Tester-AD9850-AD9851-Digital-/320770379189?pt=BI_Signal_Sources&hash=item4aaf678db5#ht_7461wt_1396

It doesn't say the minimum voltage pp; it only says the max is 10vpp but I assume it would probably go as low as 1vpp as required in Peter's specs...any thoughts?

I also found these other two, but the one above seemed the sweet spot...

* http://www.ebay.com/itm/5MHz-DDS-Digital-Signal-Generator-Module-Sweep-Function-CPLD-STM32-NEW-/320774544820?pt=BI_Signal_Sources&hash=item4aafa71db4#ht_6604wt_1396

* http://www.ebay.com/itm/BK-Precision-3001-Audio-Generator-/320767169052?pt=BI_Signal_Sources&hash=item4aaf36921c#ht_1473wt_1163

Thanks,

Mike

 

[Phrazemaster]

bump for previous post on signal gen and oscilloscope?

 

[Phrazemaster]

Just a little gift as a thank-you for this amazing project. What you have here is the original parts layout diagram color-coded for the resistors...It took me forever to find where everything went.

Where the resistors are 1-offs, I just left them white with black surroundings. Hope this saves someone some time in the build.

Mike

 

[Phrazemaster]

Bump bump...previous post on oscilloscopes and signal generator? I want to get my pre callibrated and the build is finally going really fast...any thoughts?

 

[Phrazemaster]

Hi, I have some multi-turn ferrite beads (photo attached). Can I use these for the green, or should I get the simpler version with no turns? I was about to solder these babies in and I thought, uh oh, they might have too high an impedance, etc.

http://search.digikey.com/scripts/DkSearch/dksus.dll?x=0&y=0&lang=en&site=us&KeyWords=240-2493-nd

 

[peterc]

Those ferrites will probably work.

If there is any HF roll off, take out the extra turns of wire & run a single wire through there. this will reduce the inductance.

Peter

 

[Phrazemaster]

Thank-you Peter!

 

[Phrazemaster]

Hi gang, just thought I would post a couple pix of a pre/post jumper for the metering on the green. I just drilled a couple small holes about .100" apart next to the top connection, then took the connections in wires under the board so I can just jumper how I want the meters to work.

Might be a nice option Peter if you do another version of the board (mine's v.14).

 

[Phrazemaster]

Just a pic of the underside of the board. Yeah, I know those connections almost look they are touching; they are close! But no shorts. I used a dremel to sand off the right half of the board connector just to make sure

 

[sunyata]

Hi everybody,
My 4 channel Green Pre just became a 5 channel, going on 8 channels... :
This thing needs some extra channels. Does anybody have any kits for sale?

Best regards

/Lars

 

[Phrazemaster]

Looking terrific!

 

[sunyata]

Hi gang, I want to get a scope but I know I'm not going to use it for much other than setting things like the green pre finalizations. I found a little tiny scope, at the link below. Would this work for testing/callibrating the green and possibly other audio projects? Or is this too insignificant a scope to bother with?

http://www.seeedstudio.com/depot/dso-nano-v2-p-681.html?cPath=174

Also it says it has a signal generator; any knowledge if this would suffice or would I still need another box for that as well? It looks like it only has a square wave; Peter's doc calls for a sine so I'm assuming I still need a signal generator.

Edit: I found this signal generator for a pretty good price on eBay; this should do the trick, right?

http://www.ebay.com/itm/2MHz-DDS-Signal-Generator-Sweep-Function-Tester-AD9850-AD9851-Digital-/320770379189?pt=BI_Signal_Sources&hash=item4aaf678db5#ht_7461wt_1396

It doesn't say the minimum voltage pp; it only says the max is 10vpp but I assume it would probably go as low as 1vpp as required in Peter's specs...any thoughts?

I also found these other two, but the one above seemed the sweet spot...

* http://www.ebay.com/itm/5MHz-DDS-Digital-Signal-Generator-Module-Sweep-Function-CPLD-STM32-NEW-/320774544820?pt=BI_Signal_Sources&hash=item4aafa71db4#ht_6604wt_1396

* http://www.ebay.com/itm/BK-Precision-3001-Audio-Generator-/320767169052?pt=BI_Signal_Sources&hash=item4aaf36921c#ht_1473wt_1163

Thanks,

Mike

I found this one. I might buy it.

http://www.velleman.eu/products/view/?id=384636

 

[sunyata]

Looking terrific!

Thanks!

 

[Phrazemaster]

Hi gang, I'm happy to report...my green "rough draft"...is finished!

That means all the parts and bits and bobs in place!

NOW...getting some strange voltages lol! Including some voltages on some of the IC legs that drop over time - methinks perhaps a bad capacitor or two?

Only thing I can come up with is the silver mica caps I used were NOS; I didn't have a cap tester before I installed them (I'm getting one), so I'm going to wait until ebay delivers the cap tester before going further. That and/or I fried something! Hey, I'm a newbie, it's expected, right? lol!

I'm determined to get 4 solid channels working beautifully! So thanks in advance to the patient geniuses here who I know will assist in making this thing rock!

Happy New Year!

 

[Phrazemaster]

OK I'm gonna post some voltage readings - I highlited in red the voltages I think are off. I know that this will give clues as to what's wrong on my boards, and I'm thinking the problems are cumulative - something wrong in one part affects parts elsewhere...I really was very careful in assembly (it has taken me since 2007 to get my act together (eyeroll!!!).

Any charitable geniuses willing to give their expert eyes a look-see at these voltages? Any suggestions - besides test the caps which I will do in a week or two when my cap tester gets here - are most welcome!

Oh and one more thing; the LED's light up on all boards except my last channel (the "green" channel go figure!). Not sure why I would get no LED's lighting at all on that board, but again, that's why I R a newbie!

For reference, my PSU puts out: +48.4v Phantom, -15.25v, +15.1v

Note, I have not installed the IC's yet because I don't want to blow them up! Thanks in advance!!

 

[Phrazemaster]

Update:

Tracked down the Green channel's LED's not lighting...tested each LED, good; tested the board's output and compared voltages to the working boards; good...tested my wiring harness...good...

hmmm...only thing left is, a bad connection on my plugins...well that was it for the LED's; they now work on my Green and all channels!

Regarding the really errant voltages in my Green channel, I did try replacing the BC560 and 2 of the diodes in the metering section to see if that would help; didn't help a bit. However, rechecking all voltages after the LED's were lit (after fixing above problem) yielded the same voltages as the other 3 channels. I'm putting a pic of the voltages for IC 5 here; are the voltages in red a problem?

I still have the issues with the other voltages in all channels dropping and not matching the reference voltages; however all 4 channels have pretty much the exact same "wrong" voltages so...any thoughts?

I'm attaching a pic of the updated voltages for IC 5; see my previous post for all other IC voltages (no IC's installed yet!).

Please give me a pointer or two where to look; other than blindly replacing all transistors and diodes and zeners?

Thanks gang!

Mike

 

[Harpo]

I'm attaching a pic of the updated voltages for IC 5; see my previous post for all other IC voltages (no IC's installed yet!).
Please give me a pointer or two where to look; other than blindly replacing all transistors and diodes and zeners?

no IC's installed yet 

 

[peterc]

I'm attaching a pic of the updated voltages for IC 5; see my previous post for all other IC voltages (no IC's installed yet!).

Should be OK