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SSM2166 compressor build

Started by armstrom, September 30, 2010, 12:22:48 PM

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armstrom

September 30, 2010, 12:22:48 PM
I thought I would create a new topic for my compressor build. It's insipred by the Q&D compressor from Jack Ormon's site. I added some changes that Mark Hammer had suggested in various threads over the years as well as a few of my own. I've posted information on this build in a few other threads but thought I would give it a thread of its own in case people want to search for it at some point in the future.



Sound Clip (Warning ~3MB clip!):
http://www.mr2-power.com/cramit_test.mp3
Compression at maximum, noise gate turned down all the way (no gating), fast mode, half gain.. And most importantly NOT my playing!

Here's a PDF with the schematic and PCB:
http://www.mr2-power.com/compressor.pdf

Enjoy!



askwho69

#1
October 16, 2010, 06:33:52 AM
how about use as booster...? i it no hiss? is this Chip cheap and common
?
"To live is to die"

Mark Hammer

#2
October 16, 2010, 03:35:30 PM
Can it boost?  Yes.  VERY large amplitude output available.  Some might say too much.

As chips go, it is costly and not all that common.  But for the extra few dollars that the chip costs, you get a very easily-built and top-quality compressor with built-in noise-reduction.  The extra few dollars is a very wise investment, if you ask me.  Besides, the chassis and switch will cost you more.

Govmnt_Lacky

#3
October 16, 2010, 03:41:57 PM
I guess I don't have the "magic ear" that some people do. Can someone please explain what the effect is doing when it is engaged? What "difference" should I be hearing?  ???
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Mark Hammer

#4
October 16, 2010, 04:18:35 PM
Do you mean this one, or any compressor?

The tone will not seem that different, but the difference in volume between when you strum softly and when you dig in with the pick will largely disappear.

Govmnt_Lacky

#5
October 16, 2010, 04:22:01 PM
Mark,

Well, I must say it is ANY compressor that I have heard. So if I understand you correctly, a compressor is much like a volume leveling circuit? In that, it will raise the lower volume audio and lower the higher volume audio to a happy medium that is set by the controls?
I guess I am in need of a remedial Compressor lesson. Any idea where I can read about it?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

.Mike

#6
October 16, 2010, 06:10:12 PM Last Edit: October 16, 2010, 06:13:29 PM by .Mike
Quote from: Govmnt_Lacky on October 16, 2010, 04:22:01 PMI guess I am in need of a remedial Compressor lesson. Any idea where I can read about it?

I think that this is one of the best primers on compression. It covers some controls that are rarely seen on stompbox compressors, but are still relevant. Since it's from DBX, it also covers some features found on their compressors that are totally irrelevant.

Still, it's easy to understand. :)

Mike
If you're not doing it for yourself, it's not DIY. ;)

My effects site: Just one more build... | My website: America's Debate.

Govmnt_Lacky

#7
October 16, 2010, 06:20:23 PM
Thanks Mike!  ;) That was very informative however, I tried looking at the MXR compressor at Tonepad and the controls on that one are Level and Sustain. Which do these corespond to in the DBX essay?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

.Mike

#8
October 16, 2010, 06:42:14 PM
The Level control is just an output volume control, referred to as the Output in the DBX document. It's used for makeup gain after the compression has been applied. According to the manual, the Sustain control (called Sensitivity on an actual MXR), sets the Ratio, but the manual also says it sets the sensitivity. Maybe someone more familiar with the circuit can answer better-- I mostly use rack compressors.

I use compression all the time for spoken word (internet radio), and it took me a long time to fully understand what it was doing. It helped to record a guitar sample of single notes and chords, and then pull it into a multi-track audio editor. Duplicate the audio on a few different tracks. Apply compression with different settings to some of the samples, and then A/B the resulting sound and the visual waveform against the original and against each other.

Mike

If you're not doing it for yourself, it's not DIY. ;)

My effects site: Just one more build... | My website: America's Debate.

Govmnt_Lacky

#9
October 16, 2010, 06:58:08 PM
I just looked up the info for the SSM2166 (Only offered by Analog Devices).

It appears that this chip is only offered in the SOIC format. Is this what the circuit was designed around? It does not appear, according to the datasheet, that this was offered in a PDIP casing.

http://www.analog.com/en/audiovideo-products/audio-signal-processors/ssm2166/products/product.html#ppa_print_table

Can someone provide a link to where I can find the PDIP version of the chip as the PDF layout appears to support the PDIP version.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Mark Hammer

#10
October 16, 2010, 07:38:02 PM
Small Bear carries them.  $8.75 may seem like a big price tag for a chip, but its good, its rare, and it is a bonehead simple build.  You'll end up with an extremely good compressor for a total of probably $40 of parts at the absolute maximum.

The Sustain control on the Dynacomp is properly described as a Gain-reduction sensitivity control.  That is, as you turn it up the unit is more likely to reduce the gain more when you pick harder.

Govmnt_Lacky

#11
October 16, 2010, 07:45:34 PM
Quote from: Mark Hammer on October 16, 2010, 07:38:02 PM
Small Bear carries them.  $8.75 may seem like a big price tag for a chip, but its good, its rare, and it is a bonehead simple build.  You'll end up with an extremely good compressor for a total of probably $40 of parts at the absolute maximum.

Thanks Mark. I saw that shortly after I posted however, it still does not clarify if it is an SOIC or a PDIP. I have to assume that since Analog Devices ONLY offers them in SOIC format that Steve also sells the SOIC chip. I have searched for a while and found no evidence that the chip WAS EVER made in PDIP casing.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Mark Hammer

#12
October 16, 2010, 08:11:21 PM
I bought 3 of them in DIP form, and my compressor uses one of them.  Analog Devices stopped making them in DIP form, but they produced enough before then to keep us folks here happy....for a few dollars more.

Govmnt_Lacky

#13
October 16, 2010, 08:25:18 PM
 :icon_cry:
Ok so I guess the question is this.... Should I put up the money to order a PDIP and go the easy route OR should I get the SOIC for FREE and deal with the soldering hassle?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

askwho69

#14
October 16, 2010, 09:06:37 PM
Wow this chip is very expensive!
"To live is to die"

Mark Hammer

#15
October 16, 2010, 09:20:16 PM
Yes....it is.  But the thing basically requires a handful of components from the pins to ground, for the most part.  You can perf this thing in less than an hour, and have a working full featured top notch compressor.  Isn't that worth something to you?  It's not like the passive components needed are all that expensive.

Govmnt_Lacky

#16
October 16, 2010, 09:20:27 PM
Not TOO bad when compared to other obselete chips (MN3007 is a good one...around $10-12!)

However, the fact that I can get the SOIC version for FREE keeps the cheapo side of me in the fight.  :icon_rolleyes:
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

askwho69

#17
October 16, 2010, 09:57:01 PM
Quote from: Govmnt_Lacky on October 16, 2010, 09:20:27 PM
Not TOO bad when compared to other obselete chips (MN3007 is a good one...around $10-12!)

However, the fact that I can get the SOIC version for FREE keeps the cheapo side of me in the fight.  :icon_rolleyes:

Which Chip, you can get it free? soic is so small :)
"To live is to die"

Govmnt_Lacky

#18
October 17, 2010, 02:45:18 PM
Quote from: askwho69 on October 16, 2010, 09:57:01 PM
Which Chip, you can get it free? soic is so small :)

I can get the SOIC version of the chip for free since it is still in production however, I cannot get the obsolete PDIP version without forking out some dough!  ;)
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

armstrom

#19
October 18, 2010, 11:38:53 AM
If you're etching a board then SOIC is easy enough to deal with, just make sure you account for the "flipped" pin layout you get by soldering to the bottom (copper side) of the board. If you use a program like ExpressPCB then it will take that into account for you. Another option is to get a SOIC to DIP adapter board, but that's likely to cost more than just buying the DIP version from small bear :)
-Matt

PS. I'll be posting a revised version of the layout soon. I have run into some issues getting my initial board layout to fit cleanly inside a standard stompbox enclosure so I reduced the board footprint and simplified the connections.
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