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Re Symetrix 501 technical question
Old 23rd February 2011
  #1
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Re Symetrix 501 technical question

maybe this is nothing to be concerned about...

I recently bought a second 501, this one has the toggle switch on/off and the Valley People VCA. The other one I have has the grey push button and probably the DBX VCA.

Here's my question/concern. I was curious how the 2 would compare sonically so I ran some casual tests by running a bass through them. What I noticed is that even with the comp OFF the toggle version passed a much stronger signal with the output knob at 0 than the grey push button version at 0. If you are familiar with the 501 you know it does not have a true bypass just a COMP In or Out button and the Output knob still works when Comp is Out. In order to get their gains to match better I have to lower the toggle Output by at least 6db (as read on the knob). I think there is a similar discrepancy in the Threshold knob as well.

Should I be concerned about this? I'm not sure if I can stereo link them anyway because of the different VCAs and circuits but if I could this discrepancy would make the units out of sync wouldn't it?

Thanks
JN
Old 5th October 2012
  #2
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Just curious if you ever got an answer for this question as I just ordered my first Symetrix 501..

Could you just turn the Valley People PCA one down to where their levels are even and go from there? Or are they that different of units?

Thanks.
Old 5th October 2012
  #3
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never got an answer - I've been using it as-is.
Old 5th October 2012 | Show parent
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Quote:
Originally Posted by John N ➑️
never got an answer - I've been using it as-is.
So I'm really curious about how the two different versions sound. Are they quite different beasts?...Is The Valley one really superior to the dBX one as is often stated by users in forums, or are they similar?
Old 5th October 2012 | Show parent
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Quote:
Originally Posted by rocksure ➑️
So I'm really curious about how the two different versions sound. Are they quite different beasts?...Is The Valley one really superior to the dBX one as is often stated by users in forums, or are they similar?
I have wondered the same thing. I have read more than once that the Valley People version is the one to get--but is this because it is more 'collectible' or does it actually sound more pleasing to the human ear? I don't buy the stuff to collect, but rather to use, so this is a point worth knowing if I ever got my hands on one of these.
Old 5th October 2012
  #6
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I had the non-toggle version first as I found a good deal on one in very good condition. A year or so later I found a decent deal on a toggle version and picked it up. So for a little while I had both and was very curious to see how big a difference there was. I only compared them on bass guitar since that is where the 501 rep lies and found there was not a huge difference between them really. Not enough to justify spending significantly more on the toggle version. I ended up selling the non-toggle mainly because of the myth of the toggle's being more desirable and because I had also picked up some other comps. To be honest I have not tried either 501 on other sources so I should see how it fares on snare, elec guitar, etc. Be that as it may, shortly after I sold the non-toggle I noticed that if I tried to engage the limiter section on the toggle 501 that I kept the output would cut out completely - no sound if I engaged the limiter - lol.

Anyway, I am a bit of a simpleton when it comes to compressors and I find the parameters as marked on the 501's attack and release to be baffling. You have to use your ears, experiment and get used to them. Although for many sources, if you want just basic compression, its hard to get better settings manually than the 'Auto' setting.

jn
Old 7th October 2012
  #7
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I own three different versions of the 501, I like them for some reason

Greenish-grey military sorta color front, rectangular push button - Valley People VCA - my favorite and most used. I upgraded to some fancier OP Amps (a real bitch of a modification) just to see what would happen, it did not make a drastic change, but it still sounds nice. There's also some kind of additional transformer in this one. I find that it has a fat and articulate midrange, and good balance. It's sort of a go-to on bass guitar for me.

Dark grey/blackish toggle switch - Allison Research VCA (early Valley People company name I think) - second most used. I put some NE5532 in here because it fried the OPA style ones I put in the other one from oscillation due to speed (or some such thing), would need additional modification to support those. I hear that the real benefit comes not just from the op amp swapping, but, by adding bypass capacitors to each one, and maybe some other things I'm not sure about too. This one seems darker and kind of bass heavy to me (on bass guitar, which I always try these on). I should probably try it again on various things, but so far I've found it a bit too heavy toned compared to the green one, at least for bass git. It works fine though and I probably still use it in some mixes on other things. The compression character is similar to the green one, but the EQ is different. No extra transformer in this one.

Blue, circular push button with the newer logo and different knobs - THAT 2150A VCA - probably least used to date. The compression character is slightly different on this one, hard to describe with adjectives. This one seems the most "middle of the road" of all of them, having fairly neutral sonics all around. I want to compare it to the DBX 160 but I guess it's sort of its own thing. They do not sound the same. Seems like it would work out for general uses, I liked it pretty well on a snare drum track I tried. I actually haven't used it much since I've had it, but I don't want to get rid of it.
Old 7th October 2012 | Show parent
  #8
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Quote:
Originally Posted by monkeyxx ➑️
I own three different versions of the 501, I like them for some reason

Greenish-grey military sorta color front, rectangular push button - Valley People VCA - my favorite and most used. I upgraded to some fancier OP Amps (a real bitch of a modification) just to see what would happen, it did not make a drastic change, but it still sounds nice. There's also some kind of additional transformer in this one. I find that it has a fat and articulate midrange, and good balance. It's sort of a go-to on bass guitar for me.

Dark grey/blackish toggle switch - Allison Research VCA (early Valley People company name I think) - second most used. I put some NE5532 in here because it fried the OPA style ones I put in the other one from oscillation due to speed (or some such thing), would need additional modification to support those. I hear that the real benefit comes not just from the op amp swapping, but, by adding bypass capacitors to each one, and maybe some other things I'm not sure about too. This one seems darker and kind of bass heavy to me (on bass guitar, which I always try these on). I should probably try it again on various things, but so far I've found it a bit too heavy toned compared to the green one, at least for bass git. It works fine though and I probably still use it in some mixes on other things. The compression character is similar to the green one, but the EQ is different. No extra transformer in this one.

Blue, circular push button with the newer logo and different knobs - THAT 2150A VCA - probably least used to date. The compression character is slightly different on this one, hard to describe with adjectives. This one seems the most "middle of the road" of all of them, having fairly neutral sonics all around. I want to compare it to the DBX 160 but I guess it's sort of its own thing. They do not sound the same. Seems like it would work out for general uses, I liked it pretty well on a snare drum track I tried. I actually haven't used it much since I've had it, but I don't want to get rid of it.
Hmm! very curious. I love mine and I have no idea which VCA it has. I also own a Valley Dynamite, which sounds completely different and a couple of DBX160x's which are a fair bit darker sounding. Mine has the smoothness of the DBX but with a seemingly much cleaner signal path.
I think I may have to pop the hood on the unit and compare notes with a few users. Great comps at a very cheap price though.
Old 7th October 2012 | Show parent
  #9
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Quote:
Originally Posted by monkeyxx ➑️
I own three different versions of the 501, I like them for some reason

Greenish-grey military sorta color front, rectangular push button - Valley People VCA - my favorite and most used. I upgraded to some fancier OP Amps (a real bitch of a modification) just to see what would happen, it did not make a drastic change, but it still sounds nice. There's also some kind of additional transformer in this one. I find that it has a fat and articulate midrange, and good balance. It's sort of a go-to on bass guitar for me.

My green unit with rectangle, has the Valley People VCA and is fantastically go-to fat on bass guitar and very usable for some electric guitar tones. It has a certain gummy texture to it, in a good way. Thanks monkeyxx for the most comprehensive review on the various 501 out there.

This is a great sub 300 dollar piece to get on ebay, unless you have to buy from flower pot guy.

John N. the funked up gain structure on the push button model is similar to the way my unit is set up as well. It may just be an anomaly between different production models (toggle vs. push button). That is a good question that you wondered, regarding linking those two units. As you speculated, it may not be possible. Anyway, even non linked and trying to match... other than a sound shootout, it would be unusual to find a scenario where one would need a stereo pair of a couple of 501s. It really is not that type of a comp.
Old 7th October 2012 | Show parent
  #10
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Quote:
Originally Posted by monkeyxx ➑️
I own three different versions of the 501, I like them for some reason

Greenish-grey military sorta color front, rectangular push button - Valley People VCA - my favorite and most used. I upgraded to some fancier OP Amps (a real bitch of a modification) just to see what would happen, it did not make a drastic change, but it still sounds nice. There's also some kind of additional transformer in this one. I find that it has a fat and articulate midrange, and good balance. It's sort of a go-to on bass guitar for me.

Dark grey/blackish toggle switch - Allison Research VCA (early Valley People company name I think) - second most used. I put some NE5532 in here because it fried the OPA style ones I put in the other one from oscillation due to speed (or some such thing), would need additional modification to support those. I hear that the real benefit comes not just from the op amp swapping, but, by adding bypass capacitors to each one, and maybe some other things I'm not sure about too. This one seems darker and kind of bass heavy to me (on bass guitar, which I always try these on). I should probably try it again on various things, but so far I've found it a bit too heavy toned compared to the green one, at least for bass git. It works fine though and I probably still use it in some mixes on other things. The compression character is similar to the green one, but the EQ is different. No extra transformer in this one.

Blue, circular push button with the newer logo and different knobs - THAT 2150A VCA - probably least used to date. The compression character is slightly different on this one, hard to describe with adjectives. This one seems the most "middle of the road" of all of them, having fairly neutral sonics all around. I want to compare it to the DBX 160 but I guess it's sort of its own thing. They do not sound the same. Seems like it would work out for general uses, I liked it pretty well on a snare drum track I tried. I actually haven't used it much since I've had it, but I don't want to get rid of it.
This is a great bit of information...thanks for posting it. It would be interesting to see pictures of the various units.
Old 7th October 2012 | Show parent
  #11
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Quote:
Originally Posted by rocksure ➑️
This is a great bit of information...thanks for posting it. It would be interesting to see pictures of the various units.
I'd like to give more impressions of a bunch of compressors on different sources, but I haven't been mixing out of the box in a while and I sold off half of them. I think if I fill out the rack with more goodies I'll probably use it a lot more. I've been in a mostly songwriting/demo mode for a good while now which is all about speed and efficiency which is where software rules. I really do enjoy using outboard vs. VSTs, it's a worthwhile pursuit.

I like the limiter on the 501s, too, I've used those a few times with good results.

here they all are nestled together in my rack
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Re Symetrix 501 technical question-compressors-001.jpg  
Old 7th October 2012 | Show parent
  #12
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Quote:
Originally Posted by monkeyxx ➑️
I'd like to give more impressions of a bunch of compressors on different sources, but I haven't been mixing out of the box in a while and I sold off half of them. I think if I fill out the rack with more goodies I'll probably use it a lot more. I've been in a mostly songwriting/demo mode for a good while now which is all about speed and efficiency which is where software rules. I really do enjoy using outboard vs. VSTs, it's a worthwhile pursuit.

I like the limiter on the 501s, too, I've used those a few times with good results.

here they all are nestled together in my rack
Cool thanks for posting the picture...it is now easy to visualize the different models. By the way you are right in saying Allison Research was the early name for Valley People ( I think Allison was the name of founder Paul Buff's wife).
Old 8th October 2012
  #13
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I had the blackface 501 for years and loved it. It has very little color to it so I can use it on vocals, guitars, bass, pretty much anything.

I bought one of the ones with the push-in switch so I could have another one but it sounded awful. Got rid of it. It had the dbx/THAT VCA in it. Luckily was able to find a couple more of the good ones with the Allison/Valley VCA.

Regarding the problem of different levels with two different units. I suspect that one has the transformer option. If you are using the 1/4" outs, they are electronically balanced so a non-TRS connector will only give you have the signal. Hope that helps.

Using the two different versions in a stereo link? No, the circuits are too different between the two to get reliable stereo operation.
Old 9th October 2012 | Show parent
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Quote:
Originally Posted by monkeyxx ➑️
I'd like to give more impressions of a bunch of compressors on different sources, but I haven't been mixing out of the box in a while and I sold off half of them. I think if I fill out the rack with more goodies I'll probably use it a lot more. I've been in a mostly songwriting/demo mode for a good while now which is all about speed and efficiency which is where software rules. I really do enjoy using outboard vs. VSTs, it's a worthwhile pursuit.

I like the limiter on the 501s, too, I've used those a few times with good results.

here they all are nestled together in my rack
Noticed you have a 651 there as well. How does it compare to the 501?
Old 9th October 2012 | Show parent
  #15
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Quote:
Originally Posted by David_Kessler ➑️
Noticed you have a 651 there as well. How does it compare to the 501?
I'd say the 501s are a bit more obvious in compression, and the 651 is a bit more "transparent," the 'can be almost invisible' type, like an RNC but I like it better. It still has a bit of a "tone" to it though, what I've heard someone describe as a "slight grain" which I've heard becomes more pronounced when driven hard (haven't tested this). In some kind of way I associate this tone with NE5532 op amps to some degree, which I think is what's in these. It's quite nice, wish I had a pair to mess with.
Old 16th October 2012
  #16
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Thanks Monkey for the review on each of the units.

Just got the green/grey toggle switch 501 off ebay and I'm loving the crunch it gives bass when I overdrive it a bit.

-Ari
Old 16th October 2012 | Show parent
  #17
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Quote:
Originally Posted by Ari.Ausar ➑️
Thanks Monkey for the review on each of the units.

Just got the green/grey toggle switch 501 off ebay and I'm loving the crunch it gives bass when I overdrive it a bit.

-Ari
glad to hear it! yeah, I think crunch is the right word for it. I heard from Joel Hamilton that you can really push these into overdrive with the output gain knob, but I haven't tried it yet. I think you'd have to pad the output if running into a digital input, like I am.
Old 24th December 2012
  #18
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Symetrix 501 Versions

Hi Folks.
I was involved as a tech at the Symetrix factory from 1987-1994. Here are some facts I know about the 501 evolution:

1. monkeyxx's blackface 501 is the earliest model I know of - with an anodized or painted aluminum front panel, and a very different company logo; about the same vintage as the CL-100.
Rick Chinn - care to chime in?

2. Next came a version that still had toggle switches for power on, but had an aluminum front panel with a lexan graphic overlay glued to it. The print looked nice and sharp, but the lexan is fragile - be careful not to wrinkle or tear the lexan if you change pots! The company logo changed to a common font style, and to my knowledge, this was the primary era for the green-colored, square-shaped Valley People TA-101 VCA's.

3. Next came the grey-painted steel front panel, with white lettering sillk-screened on top of the grey undercoat. These actually had two different VCA's during their respective sub-era.
--A) The blue, rectangular Valley People EGC-101;
--B) A transition period that may have had a DBX 2150A mounted on a "daughter board" PCB that plugged into (was soldered onto) the motherboard;
--C) The (closer to final) revision that had the DBX 2150A directly mounted on the motherboard.

Of interest about sub-era 3 (B): many other units in the 500 Series product line went through this transition phase, I remember having to hand-solder a few daughterboard DBX 2150A's into model# 528's, possibly into 525's as well (basically anything that had a EGC-101 VCA in it).

It's possible that Dane Butcher, James Husted, or Gordon Doucette might remember some of these early changes better than I.

Bill
Old 24th December 2012 | Show parent
  #19
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Quote:
Originally Posted by Ari.Ausar ➑️
Just curious if you ever got an answer for this question as I just ordered my first Symetrix 501..

Could you just turn the Valley People PCA one down to where their levels are even and go from there? Or are they that different of units?

Thanks.
Have you contacted Symetrix? They are super easy to get ahold of.
Old 25th December 2012 | Show parent
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Quote:
Originally Posted by brainditch ➑️
Hi Folks.
I was involved as a tech at the Symetrix factory from 1987-1994. Here are some facts I know about the 501 evolution:

1. monkeyxx's blackface 501 is the earliest model I know of - with an anodized or painted aluminum front panel, and a very different company logo; about the same vintage as the CL-100.
Rick Chinn - care to chime in?

2. Next came a version that still had toggle switches for power on, but had an aluminum front panel with a lexan graphic overlay glued to it. The print looked nice and sharp, but the lexan is fragile - be careful not to wrinkle or tear the lexan if you change pots! The company logo changed to a common font style, and to my knowledge, this was the primary era for the green-colored, square-shaped Valley People TA-101 VCA's.

3. Next came the grey-painted steel front panel, with white lettering sillk-screened on top of the grey undercoat. These actually had two different VCA's during their respective sub-era.
--A) The blue, rectangular Valley People EGC-101;
--B) A transition period that may have had a DBX 2150A mounted on a "daughter board" PCB that plugged into (was soldered onto) the motherboard;
--C) The (closer to final) revision that had the DBX 2150A directly mounted on the motherboard.

Of interest about sub-era 3 (B): many other units in the 500 Series product line went through this transition phase, I remember having to hand-solder a few daughterboard DBX 2150A's into model# 528's, possibly into 525's as well (basically anything that had a EGC-101 VCA in it).

It's possible that Dane Butcher, James Husted, or Gordon Doucette might remember some of these early changes better than I.

Bill
And THIS is the kind of stuff that makes me LOVE Gearslutz!!!
Old 14th September 2014
  #21
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Resurrecting an old yet chock-full thread of Symetrix 501 info. I just scoffed one of these for low coin, but it needs some TLC before I can judge its performance. However...

My unit has the grey faceplate w/rectangle power button and blue Valley People ECG-101 VCA. Can anyone (perhaps Monkeyxx) comment on whether or not there are sonic differences between the earlier green Valley TA-101 VCA vs. the later blue ECG-101?

Also, I'm curious to know if anyone's interested in starting up a simple S/N based registry? Just for revision comparasions and such.

Last edited by Analok; 14th September 2014 at 07:30 PM.. Reason: P/N Correction
Old 14th September 2014
  #22
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🎧 10 years
Some Compressor Info

First off, the TA in TA-101 stands for Transconductance Amplifier, the EGC in EGC-101 stands for Electronic Gain Control.

As for tonal differences, it's been years since I did a shoot-out between them all, but if memory serves the TA module had a little more warmth and distortion, the EGC had a crisper, cleaner sound, the DBX-2150 was quieter than the other two, but perhaps a little blander. That would be comparing the sounds with NO COMPRESSION engaged!
The 501's never had a "Hard-wire bypass" to my knowledge, the audio signal always ran through the VCA, it was the Sidechain that was in fact switched in or out.

What few realize about these compressors, (and most compressors in general) is that
most of the obvious sonic magic doesn't come from the VCA's at all (maybe 5-10% contribution to the sound), but comes from the detection/control side of the circuitry- otherwise known as the Sidechain.

In these units (Symetrix 501's, 525's, 528's, etc.) the Sidechain was implemented as a "feed-forward" design, rather than "feed-back" design, meaning that the signal was split into two parallel paths after the input amp: the audio chain, which went directly into the VCA, and the Sidechain. In a "feed-back" design (such as exists, I believe in the Aphex Compellor) the output of the VCA is returned to the Sidechain input.
In the Sidechain, a great deal of math-related Mojo occured (many times these circuits are described as Analog Computers). The signal is first Rectified (giving an Absolute Value) and Log-to-Linear converted (converting a logarithmically changing input to a linear millivolts per dB output), fed to a Threshold Detector (signal passes when it excedes a stable reference voltage) then the real magic starts: a series of complex Low Pass filters of this changing DC signal smooth it's response, and act as a sort of Value Accumulator (like an Analog Memory) that attempts to "Average" the signal level so that the compression action will be more representative of the slower "Loudness Envelope", and less about the "Harmonic Envelope". In a sense, this filter section is like an ADSR Envelope Generator circuit in a synth- in fact in the "better" (i.e., more user controllable) compressors like the 501, the Attack and Release knobs do just that, although in a logical inversion of the way a synth ADSR works.

In a sound-generating synth, the Attack control directly changes the "sharpness" of the sound's onset, the faster the attack, the "quicker" the sound appears, but with a compressor's Attack control, the faster the sidechain responds, the fewer Peaks will sneak-through to the output, making for a "smoother" sound. The Release control is likewise logically inverted compared to a synth's ADSR.

What many people describe in the sound of compressors as "grainy" or "distorted" is not "Saturation Distortion" (like clipping the front end of an amp), but rather what I choose to call "Heterodyning Distortion", which is more like Intermodulation Distortion.
This is usually caused by the Attack/Release circuits in the Sidechain being set too fast for the program material, which imposes modulation onto the "Harmonic Envelope" rather than the "Loudness Envelope" of the signal. The differences between the two envelopes are really just a question of timescale, with "Loudness Envelope" being psychoacoustically perceived in the realm of the very low and sub-sonic frequencies and periodicities.

As far as a Serial Number database, i'm not sure if the Service Department or Engineering has any of those records after all these years. I kept a repair log of units I worked on in the Final Test phase of production for a few years, but that may have been discarded in one of the many household moves I've made.

Anyway, hope this rather long post helps to elucidate!

Bill
Old 15th September 2014
  #23
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Lol! Elucidate -Yes!! Thank You, Bill. This was all quite heady but very interesting! Transconductance Amplifier, eh? Good to know! And, all the magic lies within the sidechain...hmmm. So, would you say that the op amps played a greater role in the sonic qualities of each revision change? If I'm not mistaken, my unit is filled with socketed Rohm BA4560s. Not much comment here over their musicality (everyone is "Burr-Brown" this & "Burr-Brown" that). I assume
they're just 'run of the mill' components.
As for the registery, I wasn't looking to document every unit out there, just what might be lingering about within our 'click'. Something that might buck the myth that a toggle switch makes all the difference.
Old 15th September 2014
  #24
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So, to put it all into perspective, the Rohm BA 4560's weren't the fastest op-amps out there (the LF 353's used in some of the Symetrix parametric EQ circuits were faster, but with a bit more noise and DC offset if memory serves), but they had descent current driving capabilities, and more importantly, were better than the 741's, (which were closer to 1st generation for op-amps in general). Could they be considered vanilla op-amps with today's advances? Yes, but to re-state things- they contributed maybe 2%-3% to the sound of the 501's.

Very little needed to be done in order to maximize or tweak the audio path circuits to their full potential, and most of the benefit would actually be heard by modifying those of them in the audio path only. Changing the feedback (compensation) capacitors from the Symetrix standard of 47pf to as little as 10 pf helped increase the bandwidth a little (done with great care to avoid oscillation instability), and only on the input and output op-amps. Also, bypassing an electrolytic DC blocking cap with a smaller value in parallel may have helped the highs a little.

The main point about all this is that from the standpoint of passing a signal cleanly (more like a straight wire), the Symetrix 501 topology was already excellent; just input amp, VCA, and output amp(s). I was regularly amazed that without mods the 501's could pass 50 kHz sine waves with relatively little phase shift, and of course extremely low harmonic distortion (THD).

There again the sidechain still held most of the magic, and with only a couple of ideas implemented could have held its own with some of the best compressors in the world subjectively (in a proper double-blind test) for a majority of users. Because of the tasks being asked of the Sidechain, much less would be gained by going to exotic components and part-type substitutions, but instead would require component value and topology-level changes to have the greatest impact on final audio quality IMHO.

Would Burr-Brown (and other exotic modern op-amps) help? Possibly, but with ever decreasing magnitude of results, and with an exponential increase in cost. I'd love to have time and resources to try some of these out, but I'm sure the results would be extremely subtle, if not barely perceptible. Don't get me wrong, I'm fully supportive of careful experimentation, and would love to hear about the results of mods to these venerable old circuits.

I like your idea of a database of revisions for the 501's (and other Symetrix pieces) if for no other reason than to uncloud the historical record for posterity. I'm not sure how much I can help there, however, as most of the 501's & CL-150's I own are ones I personally resurrected from the "dogpile" (our term in production for difficult-to-fix/troubleshoot circuit and other defects) and bought at the yearly internal "firesale", without proper serial number coding (as I had to match the chassis metalwork up to PCB's that were possibly from a different revision level, etc.).

Thanks for the interest, Analok

Bill
Old 17th September 2014
  #25
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Thanks again, Bill. With all you've stated above I'm pretty fixed on believeing that Symetrix did their homework on this design, and that any mods towards it would prove of little benefit. And the timeline you'd posted earlier in the thread is extremely helpful. I'd always thought it to be bizzarre in selecting a piece of gear soley by the type of power switch it had!! Transitional units will always exist from all manufacturers. But it's these units that hold collectability, in addition to their sonic signatures. This was what I was aiming towards in starting up a registry, in hopes of discovering whereabouts a key component was truly phasing out in lieu of an alternate. Thus, a certain signature could be better assumed from the earlier units in the series by means of a serial number study. Perhaps I'm overthinking this. I mean after all, it's just a compressor!
Old 22nd December 2014
  #26
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Hi guys, i have been reading this thread because i just bought a 501, gray paint, white buttons, rectangular push button, serial 73422.
The information you offered here is amazing!

I have 2 questions that you may resolver for me, first is if the 501 can be configured to work at 220v without an adapter, and second, i read somewhere that this units are very old and will benefit from a recap to work well... how do i know if this is necessary?
Old 22nd December 2014
  #27
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🎧 15 years
A recap would be done mainly if you are having excessive hiss and noise, from old electrolytics drying up I think.

Sorry I can't advise on a 220V modification, I've never messed with that.
Old 22nd December 2014
  #28
Lives for gear
 
Mertmo's Avatar
 
🎧 15 years
Quote:
2. Next came a version that still had toggle switches for power on, but had an aluminum front panel with a lexan graphic overlay glued to it. The print looked nice and sharp, but the lexan is fragile - be careful not to wrinkle or tear the lexan if you change pots! The company logo changed to a common font style, and to my knowledge, this was the primary era for the green-colored, square-shaped Valley People TA-101 VCA's.
This is the one I have. Sounds good, strong and slightly dark.
My limiter section never worked, gonna have to fix that someday...
Old 22nd December 2014
  #29
Gear Addict
 
blueNan's Avatar
 
🎧 5 years
Thank you monkeyxx... looking forward to receive it and check!
Old 23rd December 2014
  #30
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Analok's Avatar
 
4 Reviews written
🎧 10 years
If I'm not mistaken, the 501's power supply has an internal switch to configure it for either 115V or 220v. Simply slide it to where the required mains voltage is shown. Easy. As for the limiter section, it needs a strong incoming signal to trigger it, and if your crushing the signal at the compression end it'll hold the signal back from triggering the limiter to some extent. Sometimes a DI box doesn't cut it, especially if your pushing single coil pups. Putting a Rane MS1b at the front end cleanly solves all your wimpy gain issues. My $0.02.

Last edited by Analok; 23rd December 2014 at 02:02 AM.. Reason: Added content
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