Keeley Compressor C4 [gut shot]  [traced]

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Re: Keeley Compressor C4 [gut shot]

Postby guycapuano » 30 Jul 2012, 14:32

So how important are the tant capacitors to the tone of this pedal? Do you think it truely makes a difference?
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Re: Keeley Compressor C4 [gut shot]

Postby IvIark » 30 Jul 2012, 15:19

Well someone on my blog made it with and without tants and said there were differences and it sounded much better with tants, but I haven't tried it myself yet. My aluminium electrolytics seem to have much greater tolerances than tantalums, with some electros having -20% and +80% tolerances listed which is really poor. My tantalums all seem to have 10% tolerances and if the same is true with other peoples then the difference in capacitance could account for some differences. But I'll be certainly trying it when I build one to see for myself with matched components.
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Re: Keeley Compressor C4 [gut shot]

Postby guycapuano » 30 Jul 2012, 20:04

IvIark wrote:Well someone on my blog made it with and without tants and said there were differences and it sounded much better with tants, but I haven't tried it myself yet. My aluminium electrolytics seem to have much greater tolerances than tantalums, with some electros having -20% and +80% tolerances listed which is really poor. My tantalums all seem to have 10% tolerances and if the same is true with other peoples then the difference in capacitance could account for some differences. But I'll be certainly trying it when I build one to see for myself with matched components.


Yeah I saw that, but hes the only DIY guy I have ever heard say it made any difference.
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Re: Keeley Compressor C4 [gut shot]

Postby IvIark » 30 Jul 2012, 20:13

Well you can either try for yourself and see whether they make any difference to your ears, or just use normal electros if you're not bothered. That's the beauty of building your own pedals, you can do whatever you want to do.
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Re: Keeley Compressor C4

Postby Fix_Metal » 05 Nov 2012, 15:27

vietpham wrote:Hi all, attached is the guts of the Keeley C4. I've tried to draw as much as I can and though there are still some part missing. It's pretty much the same as a Ross Compressor. Hope this be of little help. This is a double sided circuit. White line is the front, red line is the back trace.

Rgds

V

Any infos bout the original transistors? Seems to me they are MPSA18 (at least for what I think I'm reading on the lower corner BJT).
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Re: Keeley Compressor C4 [gut shot]

Postby Fix_Metal » 11 Nov 2012, 11:38

2SC1849 had been used in the old revisions of the pedal (no solder mask/silk screen on pcb, just etched, ~2003).
Stated here and confirmed by this pic (it's a little hard to read though)
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Re: Keeley Compressor C4 [gut shot]

Postby andromeda » 26 Feb 2013, 18:45

hy guys,are there many differences between ca3080 metal case and ca3080n?
i've completed this compressor with ic metal case (to99) rca,and voltages are good,but it don't work has it should... suppose that the problem is just in ca3080. :cry
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Re: Keeley Compressor C4 [gut shot]

Postby mictester » 26 Feb 2013, 23:58

andromeda wrote:hy guys,are there many differences between ca3080 metal case and ca3080n?
i've completed this compressor with ic metal case (to99) rca,and voltages are good,but it don't work has it should... suppose that the problem is just in ca3080. :cry


What's wrong with it? "Don't work as it should" doesn't give us much to go on!

There should be no difference between the 8-pin DIL and the metal can octal versions of the IC - they are specified identically. The only difference is the metal can version is ancient, usually from the early 70s, so has a bogus "mojo" value. That's why I've seen this $0.35 IC advertised to the gullible for $85.00!

Anyone want some genuine JRC 4558 ICs? As used in the original Tubescreamers. Only $44.99 each, posted to anywhere in the world.
I'll bet I'll get some takers.....
"Why is it humming?" "Because it doesn't know the words!"
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Re: Keeley Compressor C4 [gut shot]

Postby andromeda » 27 Feb 2013, 05:36

mictester wrote:
andromeda wrote:hy guys,are there many differences between ca3080 metal case and ca3080n?
i've completed this compressor with ic metal case (to99) rca,and voltages are good,but it don't work has it should... suppose that the problem is just in ca3080. :cry


What's wrong with it? "Don't work as it should" doesn't give us much to go on!

There should be no difference between the 8-pin DIL and the metal can octal versions of the IC - they are specified identically. The only difference is the metal can version is ancient, usually from the early 70s, so has a bogus "mojo" value. That's why I've seen this $0.35 IC advertised to the gullible for $85.00!

Anyone want some genuine JRC 4558 ICs? As used in the original Tubescreamers. Only $44.99 each, posted to anywhere in the world.
I'll bet I'll get some takers.....


I mean that the sound output, it is little compression .... almost imperceptible.
if set to maximum volume control, the sound distorts.
I used all 2N3904
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Re: Keeley Compressor C4 [gut shot]

Postby mictester » 27 Feb 2013, 07:16

Look at the DC voltage going to pin 5 of the 3080. Does it vary with each note played?
"Why is it humming?" "Because it doesn't know the words!"
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Re: Keeley Compressor C4 [gut shot]

Postby andromeda » 02 Mar 2013, 17:04

:secret: i ve reduce the gain problem with a 29k resistor to a pin 5 of 3080....thx...but the compression effect is very impercetbile,the sound is very clean but not very compressed...
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Re: Keeley Compressor C4 [gut shot]

Postby andromeda » 03 Mar 2013, 19:59

this the project..
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mr coffee (28 Jan 2018, 17:27), Nicht Bernd (16 Oct 2013, 09:29), pedalgrinder (04 Mar 2013, 07:06), rocklander (03 Mar 2013, 20:58)
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Re: Keeley Compressor C4 [gut shot]

Postby agoldoor » 19 Mar 2013, 19:37

Hey guys... what did y'all do in terms of the 150K pots? I have been searching for someone who answered this question, but I didn't find anyone answering it.
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Re: Keeley Compressor C4 [gut shot]

Postby agoldoor » 19 Mar 2013, 21:36

EDIT: I should add... what did y'all do in terms of the 150K pots that you found satisfactory? Because obviously I could create a pot with a max of 150k with a resistor across a 500k... but would the sweep then be satisfactory?
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Re: Keeley Compressor C4 [gut shot]

Postby bufferbrad » 16 Oct 2013, 00:23

Hey guys,
So im building this 4 knob version of the keeley for a school project. What I was wondering about is the clipping linear/log pot issue. Im confused as to what you guys mean. Any help would be appreciated as im going for best sound (obviously).

Also im implementing a blend control based around a 741.

Very Excited about this project
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Re: Keeley Compressor C4 [gut shot]

Postby mictester » 16 Oct 2013, 06:40

bufferbrad wrote:Also I'm implementing a blend control based around a 741.


Don't! The 741 is a noisy old current hog. Use a TL071 instead - low noise, low current and the same pinout as the 741.
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Re: Keeley Compressor C4 [gut shot]

Postby tiococo » 13 Jan 2018, 18:14

mictester wrote:A massive improvement can be obtained by duplicating the transistor that's connected to the output of the CA3080. The one that's there already (with the equal emitter and collector resistors) can continue to be used just as a phase splitter to feed the two recifier circuits. The additional transistor has its base connected to the base of the existing transistor, and has 10k from emitter to ground and 10k from collector to the supply rail. The output is then taken from the emitter of the additional transistor. This prevents the clipping that can occur at the emitter of the original device due to the action of the rectifier appearing in the output - this is meant to be a "clean" sustainer, after all!

I'll post an amended diagram later...


MicTester
Did you meant this? Isolating the output from the rectifiers?
[img]c4cleanmod.png[/img]
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Re: Keeley Compressor C4 [gut shot]

Postby tiococo » 14 Jan 2018, 14:14

Ok! Confirmed the mod by mictester I'm finishing the layout today to start soldering. If its all ok I'll post it here :)
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