3080-based compressor builders - Do not despair!

[Mark Hammer]

Searching for a file this evening, I inadvertently stumbled across acan I had of the modules for the old Ibanez UE400 Multi-effects unit.  This unit contains a compressor and, guess what, it doesn't use a CA3080.

Largely similar to both the Dynacomp and Ross units (including the 150k resistor you can convert to an "attack/recovery" control), the circuit uses half an LM13600 - a cheaper and still available chip.  Pleasingly, it also sticks an op-amp gain recovery stage after the OTA which affords an opportunity to custom tailor the tone a bit, including taming hiss and compensating for the usual treble loss.

I've posted the schematic here: http://img.photobucket.com/albums/v474/mhammer/UE400-CP.gif

I also posted the schematic for the phaser from the same rackmount unit:  http://img.photobucket.com/albums/v474/mhammer/UE400-phaser.gif
You will note that the unit - an otherwise standard 4-stager - uses discrepant caps, .047uf for the first two stages and .01uf for the last two.  The watchful eye will also note the use of a ground-leg network in an op-amp in the feedback loop to give a slight treble bump to the regen signal.

Incidentally, if you were looking for something to do with the other unused half of the LM13600, the old Korg NGT-1 Noise Gate also uses half of an LM13600.  That might make a nice one-two combo for dynamic/noise control.  That schematic is here: http://img.photobucket.com/albums/v474/mhammer/NoiseGateNGT-1.gif

Enjoy!

[nelson]

Hey Mark

I cant make out the compressor schematic AT ALL, it looks like a charcoal drawing that has been left in the rain...


btw, your a genius...............


:wink:

[Fp-www.Tonepad.com]

I'm very interested  :shock:


But that schematic is not readable as nelson said.


Fp

[grapefruit]

I wonder why they used a 2SC2785 for the output buffer in the Korg noise gate rather than the LM13600 buffer.....

Stew.

[Bill Bergman]

Save the file and open it in a paint program or powerpoint and set the fill to black. Then you can read the schematic

[Vsat]

Mark,
The UE400/401 schematic collection is part of a set of photocopies I gave you a couple of years ago! I remember you're comment at the time was something like "that distortion module looks like a Tubescreamer but uses an 6552 instead of a 4558"...
Mike

[Fp-www.Tonepad.com]

Holy sh*T Bill!!! how did you figure that out!!!!?



Fp

[TheBigMan]

Here's the schematic for the CP-9: it may not be exactly the same but it certainly uses the same chip and it's legible.

[Dirk_Hendrik]

Good to see my schem still goes around. Exactly what I intended :wink:

Compare it to the schematic of later master and power series Ibanez compressors. They're practically the same other than that another chip is used for the VCA.

[puretube]

http://www.musicianshotline.com/archive/monthly/pedal_power/0605.htm

[bioroids]

I wonder with the don't use the linearizing diodes for a cleaner sound....

Thanks for sharing!

Miguel

[brett]

Do the linearising diodes make much difference?  The only time I used them I thought they didn't make any improvement.  But maybe I was making a ring modulator and the tone was bells and hammered metal anyway.  In a compressor, they might be worth using. Hmmm... The details in memory banks have been deleted...

[Paul Perry (Frostwave)]

http://et.nmsu.edu/~etti/winter98/electronics/grise/wrg.html
top of the pile for Google    linearizing diodes

[Paul Perry (Frostwave)]

Don't know what happened there, don't seem to be able to edit???
anyway just wanted to add this link for another OTA analysis (WARNING: MATH)  stromeko.synth.net/diy/OTA.pdf

[Mark Hammer]

Mark,
The UE400/401 schematic collection is part of a set of photocopies I gave you a couple of years ago! I remember you're comment at the time was something like "that distortion module looks like a Tubescreamer but uses an 6552 instead of a 4558"...
Mike

Sorry about that, Mike.  Meant to stick in a credit line for you but between people bugging me while I was trying to type, and my desire to get off-line and go watch the football game, it slipped my mind.

Incidentally, paid a visit to L-Tronix yesterday and they have stopped carrying semiconductors.  

On the other hand, Reset has now started carrying "surfboards" for adapting SMT/SOIP devices to more standard formats.  Now we can finally do something with those Wavefront chips I got a while back.

[Mark Hammer]

I cant make out the compressor schematic AT ALL, it looks like a charcoal drawing that has been left in the rain...

To save on space, I had that schem saved as a 4-bit (16 colour) GIF.  I'm wondering if the problem is the use of the 4-bit format.  The phaser was in 1-bit (black and white) format, as was the Korg noise gate.

[Vsat]

Mark,
Too bad about L-tronix, parts didn't appear to be their mainstay though.
Mail order becoming more necessary in Ottawa area these days, especially since a litre of gas costs more than the part you want  :

If you are so inclined feel free to put up more  or all of the Ibanez UE40x
schemos. People ask about these now and then, an seem to like the units.
Cheers, Mike

[bioroids]

http://et.nmsu.edu/~etti/winter98/electronics/grise/wrg.html
top of the pile for Google    linearizing diodes

Thanks, thats an interesting link.

I've read somewhere that the linearizing diodes do help to extend the linear region, but changes the characteristic of the distortion as well. So when the linear region is exceeded, the clipping is pretty awfull sounding. At least that was what I understood  :oops:

So the compromise would be more distortion (without the diodes) vs. less distortion but awfull clipping when exceeded (with the diodes)?

I tried this with a SVF using a JRC13600 and sounded in fact cleaner with the diodes, but the breadboard was really a mess so I'm not very confident of the results of the test.

Luck

Miguel

[Paul Perry (Frostwave)]

So the compromise would be more distortion (without the diodes) vs. less distortion but awfull clipping when exceeded (with the diodes)?

If it is so, then maybe we have a new kind of distortion!!!!
just run sig into the LM13700 & adjust the linearising diode current, to change the distortion!
Would combine nicely with another control that runs a variable amount of same signal to the amplifier bias pin, to give variable amounts of second harmonic via multipliction!

[Greenballs]

Do I win a prize for the longest time between the last post and the necro bump?

I'm building the compressor from the schematic linked by the OP. A friend of mine used to own a UE400 and really liked the compressor in it and so asked me if I could build one for him.

I've got the circuit on the breadboard, including an 18v charge pump, with most of the components listed on the schem present and correct barring a few resistor values that I've got on order and a 4558 chip in place of the 6552. The circuit works, but only if I bridge pins 2 and 3 on the 4558, which obviously aren't bridged on the schematic and I noticed that the chip isn't hooked up to the 18v supply via pin 8, rather via a 220k resistor to pin 3. Also, its pretty noisy hiss wise...

Could someone please educate me as to why this section of the circuit, which I assume to be just gain recovery, is designed the way it is? And why doesn't it work properly, for me at least?

I've reattached the schem from the original post. Thanks in advance!