My studio Mic compressor build

[jfrabat]

For those new to my posts, for several reasons (slow PC, entertainment factor, and just because!) I decided to make myself some hardware for my home studio.  Among the stuff I intend to make are:

• 4 Band Semi-Parametric EQ
• Compressor
• Tube Preamp
• Solid State Transformer Preamp
• De-esser

Some work is already advanced; for example, here is the finished EQ:




You can read more about that one here and here.

And here is how the Solid State Transformer pre-amp looks like as of today (it is a kit from Five Fish Audio, which I modified to have an OLED VU Meter; waiting for some connectors to arrive to continue the build):



More about the mod for that one here.

And here is the Tube Preamp (also a kit I am modifying; waiting for some parts to arrive to define where everything goes so that I can continue the build):



As for the De-Esser, I intend to start working on that one once I finish everything else (too much on my plate!).  But that story is here, and I intend to build this one.

But the one that got the ball really rolling is the compressor.  If you are interested, you can follow that story here and here.

But to sumarize the story, I was looking for a good vocal compressor, and it was suggested to me to build an old design published in an article of Electronics Today (DEC 1985) magazine.  Well, that schematic had some issues, but with LOTS of help from this forum, it was figured out.  So, I got myself some boards made, and started getting my parts ready.  Well, the board finally arrived, and the build is finally started.

First of all, this will be my (external) power supply (+/-15VDC):





And this is the board I got today:



And here is today's progress:



Regarding the transistors, I typically prefer to use sockets, and I originally did on this one as well, but they were so loose, I decided to just solder them directly to avoid issues down the line.  All ICs are socketed.

Tomorrow I will start connecting all the off-board components (jacks, switches and pots) and will try to test it out this weekend (if all goes well).  Will also try to get the enclosure done this weekend (already got the waterslide decals done).  Anyway, no questions or troubleshooting requests (YET!), but I am excited about the progress and wanted to share with you all here!

Felipe

PS: The two names I dedicate this board to are my son and daughter.  And Pipe is pronounced Pipeh in Spanish (which is a nickname for people named Felipe).  Nothing to do with anything else (have already been asked about that!).

[11-90-an]

No pitch shifter or envelope filter...

That already said...
Kudos to you, Felipe! Talk about determination... 

[aron]

Looks incredible! How did you make the front panel graphics/labels???

[jfrabat]

No pitch shifter or envelope filter...

That already said...
Kudos to you, Felipe! Talk about determination... 

Give me time...  I will probably get bored at some pont and start something like this.  The I will be asking for your help because I bit off more than I can chew!!!   

Thanks, by the way!

Looks incredible! How did you make the front panel graphics/labels???

Transparent inkjet waterslide stickers.  Have been using them for years in my pedals, but look AMAZING with the brushed aluminum finish!

[aron]

Is there any brand of the inkjet stickers you are getting? That looks incredible!

[jfrabat]

Mine are World Paper Clear Ink Jet Water Slide paper.  I bought mine off Amazon years ago.  Just looked for it now, and could not find the same brand.  But I doubt the vary much.  Just be sure to buy the right one for your printer (Laser or Inkjet) and be sure they are transparent and not white.  There was a learning curve to getting them to turn out good, but good they do turn out.  If you do it wrong, the sticker will stretch, and nothing will line up, which is a real PITA.  Use a rubber squeegee to finalize the placing (be 100% sure it is in the right place!  Trying to pull it after the squeegee will also stretch it!).  Also, let them dry for 24 hours before cutting out any holes (first drill all holes, then lay down the sticker, then cut the holes with an X-Acto with a fresh blade).

Just timing, I guess, but I JUST finished putting on the ones for the compressor on the face plate (although I think I will need to order a 1402D because the 1402B is not deep enough; both have the same size of face plate, so no issues there).  I still need to do the rear of the compressor and the EQ.  EQ I had to take the one I had off, as I put it on backwards (DOH!), so I ended up with the IN where the AC comes in and AC where the input is.  The new one is made and ready to go on (just need to take apart the EQ to do it); for the compressor, I took it out of the water and noticed I wrote IN twice instead of IN and OUT; so back to the printer!

[jfrabat]

Just to update.  Finished the front and rear panel (finish and artwork).  Already got some switches soldered, and will move on to the pots tomorrow.  Not sure I will get to finish the jacks on the back in time (I also need a stereo switched jack, which has not arrived yet).  Here is what it looks like as of today:

Front:

Imagine the difused LED's sticking out of the holes to get a completed image.  Power will be red, compressor will be green, green, yellow, red, and gate is a red/amber/green single LED.

Rear:

The power connector (left side hole) is just sitting behind the hole.  It will be MUCH closer once installed.  External trigger jack needs to be replaced with a switched one, and all the bolts are not yet installed for the power or XLR connectors.

It matches nicely the EQ...  At the very least, it looks like part of a set.  I am very happy so far with how it is looking.  Just hopes it works!!!

[jfrabat]

Rear:

The power connector (left side hole) is just sitting behind the hole.  It will be MUCH closer once installed.  External trigger jack needs to be replaced with a switched one, and all the bolts are not yet installed for the power or XLR connectors.

Well, there you go...  I did it again...  I made the panel backwards!  Darned dyslexia!!! Now I am in the process of inverting it (new sticker and a couple of new holes).

[jfrabat]

Updating the status.  This is as far as I got today...

Corrected the back plate issue.  All pots and switches are wired.  XLR's are also wired, as are some jacks, but I am still pending to wire 4 (one of them is switched, and has not yet arrived).  All LED's still pending to be wired up.  And also waiting for the new (longer) enclosure (face plates are the same, so I will use the ones I already made).  Also ran out of M3 nuts, so need to go to the hardware store tomorrow.  Need to get some M2 nuts and bolts as well for the power jack.

[StephenGiles]

Looks very good!!

[jfrabat]

Today's update.

The new enclosure arrived.  It fits VERY NICELY!  I could not help myself and threw the whole thing together for a casting session!  LOL!

Here is the internal fit.  Not the that LED's are just set for the photo shoot and not soldered on yet.  I am also waiting on the switched jack to arrive.



And the rear with the power connector (it will be a custom 4 pin connector to have +/-15V and GND - And YES, I did write +/-12V in the sticker by mistake!):



And, OF COURSE, I had to place it next to the EQ to do some shots of that!

[Marcos - Munky]

They both looks amazing!

[jfrabat]

I am dying to test it, but the darn cable to make the power supply connection has not yet arrived!  I feel like a kid on December 23rd...  Can time actually move slower???

By the way, LEDs are now soldered in.  Nothing else I can do now but wait...

[jfrabat]

Well, cable and connectors arrived, so I did what a normal person would do...  Get the power supply hooked up, and fire it up!

However, I may have taken that a little too literal!  I smoked (literally!) an IC.  IC2 started smoking as soon as I flipped the power button.  LED's started dancing around, and IC2 went up in smoke.  I immediately flipped the switch back to off, took the IC out and started troubleshooting.  I then noticed that pins 3 and 4 had continuity, so I thought I had a solder bridge under the socket.  Took out the socket, put in a fresh NE5532, and flicked the switch.  LED went nuts again, then... Puff!  More smoke.  Flicked it back off.  Rechecked that ground was in fact rounded, and now there was no connectivity between V+ and GND.

Took out the IC, and powered it up again.  No LED's going nuts (only power and gate turned on), and no smoke.  Took voltage readings from the socket.  This is what I am getting from IC2:

1: -3.47V
2: -3.51V
3: 0V (supposed to be connected to GND, so we are good here)
4: 15.13V (fine, as it is supposed to be connected to V+)
5: 0V (supposed to be connected to GND, so we are good here)
6: 0.205V
7: 0.395V
8: -14.91V (supposed to be connected to V-, we are good)

I don't get it.  What is going on here?  Why is this NE5532 burning up? The data sheet says it should be able to handle +/-22V, and I am only using +/-15V!

EDIT: Here is the schematic:



NOTES:  AG is Audio Ground and CD is Circuit Ground.  They are kept separate, and only meet at the beginning of the circuit where the ground comes into the board.

[11-90-an]

hold on.. shouldn't pin 4 be negative voltage and pin 8 the positive?
try turning the ic 180 degrees and see what happens...

EDIT: and now I realize that your schematic says otherwise.... 

why is your NE5532 oriented that way? I never understood why it's like that...


so IC1 is fine also?

[bluebunny]

Am I missing something here?  (Only had one coffee so far...)  The NE5532 is the same as any other dual opamp: V_CC+ on pin 8 and V_CC- on pin 4.

[jfrabat]

Oh, crap!  You are right.  I flipped + and -....  that means the whole frikking board is wrong!  I am surprised the other one did not burn as well!

[kraal]

Oh, crap!  You are right.  I flipped + and -....  that means the whole frikking board is wrong!  I am surprised the other one did not burn as well!

Shit happens. :-/

Suggested workaround: take a new socket, fold VCC+ and - pins, solder wires to the folded pins, place the socket in the existing socket, solder the wires to the pre-existing socket (VCC+ to VCC- and VCC- to VCC+), repeat for all  sockets needing it.

[11-90-an]

Oh, crap!  You are right.  I flipped + and -....  that means the whole frikking board is wrong!  I am surprised the other one did not burn as well!

Shit happens. :-/

Suggested workaround: take a new socket, fold VCC+ and - pins, solder wires to the folded pins, place the socket in the existing socket, solder the wires to the pre-existing socket (VCC+ to VCC- and VCC- to VCC+), repeat for all  sockets needing it.

I checked the schem, it seems that only your NE5532s have the wrong +/- pinouts.

Can you try pulling IC1 out and post some voltages?

[jfrabat]

Shit happens. :-/

Suggested workaround: take a new socket, fold VCC+ and - pins, solder wires to the folded pins, place the socket in the existing socket, solder the wires to the pre-existing socket (VCC+ to VCC- and VCC- to VCC+), repeat for all  sockets needing it.

I was actually thinking of cutting a socket so that no pin 4 or pin 8 remained (2 sockets now?), and using wire (I have still a small amount of it left) to connect the pins to the right hole.  May try yours, as it may look better...

I checked the schem, it seems that only your NE5532s have the wrong +/- pinouts.

Can you try pulling IC1 out and post some voltages?

I will recheck when I get home.  But from what I can see in the schematic, IC1, which is a TL072, has Pin 4 as + and Pin 8 as - in my schematic.  If google is not failing me, it should be Pin 4 - and Pin 8 +, right? 

Now, I should point out that IC1 did not burn up, smoke, or even get hot (I touched all the other ICs when IC2 burned up), and when I took IC2 out, I connected the circuit for much longer periods, and nothing burned up, so you could be right...  But I do think it is backwards.