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Question about Symetrix 501 (Compressor)
Old 17th October 2008
  #1
Lives for gear
 
musicbydesign's Avatar
 
🎧 10 years
Question about Symetrix 501 (Compressor)

Hello, Could someone explain the Symetrix 501 differences between the older and newer units. I have a late 80's with the push button power switch. Thanks for any info.

P.S. I bought it new back then from Thoroughbred Music (Now SamAsh) out of florida around 1989 or 1990. Seems like my salesman was named Brad Trumble or somthing.
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Old 17th October 2008
  #2
Gear Guru
 
AllAboutTone's Avatar
 
🎧 15 years
Not enough to differ about. 501 use to be a go to compressor for a lot of needs, ever since i found a couple Altec compressors i hardly turn my 501s on.
Old 17th October 2008 | Show parent
  #3
Lives for gear
 
🎧 15 years
A big difference is they used crappier IC's in the newer ones. Not a big deal to buy six IC sockets and six 5532 IC's to replace the newer crap IC's. VCA also changed.
Old 17th October 2008 | Show parent
  #4
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Nu-tra's Avatar
The older units with the toggle on and off switch has a valley people vca in it. The newer one has a dbX. I have both they sound the same to me.
Old 17th October 2008 | Show parent
  #5
Lives for gear
 
🎧 15 years
Replacing the opamps, especially the newer ones, makes a big sonic difference. LM4562's sound very good. They've always been great non-colored compressors. The old ones I believe have the IC's socketed, while the newer ones don't.
Old 18th October 2008 | Show parent
  #6
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musicbydesign's Avatar
 
🎧 10 years
Thanks, all for the input. Ive seen a few for sale around and it made me remember I had one packed away. I pulled it out and was just curious since people seem to ask about the powerswitch. Thanks again

-Daniel
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Old 18th October 2008 | Show parent
  #7
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Bob Ross's Avatar
 
🎧 15 years
Quote:
Originally Posted by Nu-tra ➑️
The older units with the toggle on and off switch has a valley people vca in it. The newer one has a dbX. I have both they sound the same to me.
dbx=THAT, no?
Old 18th October 2008 | Show parent
  #8
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Nu-tra's Avatar
Yup
Old 16th November 2008 | Show parent
  #9
Gear Guru
 
18 Reviews written
🎧 15 years
I just ordered a push-button model..

how many sockets/ICs will I need for one of these?

I'll look inside when it gets here but I'd like to order now if anyone knows




is it worthwile to have both the push button and the toggle switch model? if I can find one cheaply I might order its brother
Old 19th November 2008 | Show parent
  #10
Lives for gear
 
🎧 15 years
Read my post above (hint 6) LOL
Old 20th November 2008 | Show parent
  #11
Gear Guru
 
18 Reviews written
🎧 15 years
haha, oops I missed that.

I just got my grey faced pushbutton 501, it's sitting in my lap with the top off

there's actually SEVEN of the C4560C "NEC Japan" (also says 8833D) opamps in this thing

are those the "less good" ones that I should be replacing? and would the 4562 or the 5532 be preferable?



I also notice there are two transformers in this thing... is one of those an output transformer?


from what I read on these forums I was expecting the dbx VCA, but mine clearly says "Valley People Inc. EGC 101"

time to plug this thing in!
Old 20th November 2008 | Show parent
  #12
Lives for gear
 
🎧 15 years
5532's are the originals and then they went cheaper from there. The LM's listed above are modern replacements for the 5532's. I'll have to pop the hood on mine again and do some counting but I remember buying 6 IC sockets for it (have not swapped the IC's in it yet). I do remember a DBX VCA in mine.
Old 27th November 2008 | Show parent
  #13
Gear Guru
 
18 Reviews written
🎧 15 years
ok, I just got my blackface toggle switch 501... once again all the internet rumours are all wrong

this one has LF353N ICs... how do those rate on the desirability scale? they are socketed so it would be easy to swap them. unlike the grey one which has 7, this one has only 5 small opamps

what are those trim pots for? do I need to adjust for new opamps?


secondly, the VCA reads "Allison Research", NOT valley people, and not dbx. how do these rate on the desireability scale?

all I've tried it on so far is bass, but it sounds goood (and different from the greyface valley people one, the black one is crisper, the grey one is warmer and fuzzier, I think?)

lastly, this black face 501 only has one transformer. is that second transformer in the grey one an output tran.?

PS- there's also this big black box soldered on the board of the older black model, I wonder what's in there? it's about 5 times bigger than the VCA, just shiny and black and rectangular, unmarked
Old 4th November 2010 | Show parent
  #14
Gear Guru
 
18 Reviews written
🎧 15 years
just some followup observations for all of you out there in internet-land


I own three visibly different 501s, the black (dark grey) face (toggle), the greenish/grey face (square pushbutton), and the blueface (smaller black knobs, black round pushbuttons)

the character of compression of all is very similar, that sort of "clicky" bright heavily effected (squashed) VCA compression type of tone. My dbx 160X is similar, but just a hair more on the smooth n warm side of things, while still being very "effecty"

the black one has an Allison Research vca, the green has the Valley People vca, and the blue has the DBX vca. op amps were different in all three. there are other internal differences, as well.

I attempted opamp substitution in only the green and black 501s so far. The black one would not tolerate any op amps I tried, leading to kinda quiet, to obnoxiously present buzzing, due to "oscillation." so I ruined several dozen dollars worth of NE5532 and the more expensive ($4 per) ICs mentioned above. I had to go back to the 353 op amps in that one, and the noise is gone.

The green 501 tolerated the LM4652NA and sounds fine with no extraneous noise, and sounds good. I can't really say if there was a definite sonic improvement.

Now that I know about power supply decoupling I might at some point be interested in going back inside these.

besides the compression characteristic, the tonal response of the three different versions are quite varied. The blue face is the most neutral of the three, and similar in response to the DBX 160X, though with the Symetrix sounding compression. The green/grey faced one is a little lighter on the bass than the bypassed sound, and seems to emphasize midrange clarity on a bass guitar quite a bit more than the others, making it a frequent selection. The black one has an exaggerated bass boost compared to the others and the bypass sound, and sort of gives off a vibe of "lushness" to a small degree. This bass boost is often too much for my mixes on bass guitar, but I bet there'll be appropriate times or sources for its use that I have yet to encounter.

As you can tell I've pretty much only used these on bass guitar, but, I have gotten some nice sounds out of them as well when using the limiter sections in stereo on drum room mics, and softsynths. I may be crazy but these sounds ended up "fat" sounding. I'm not always a big fan of compressing kick or snare drums, but the blue 501 sounded pretty nice on kick, if you want that kind of thumpy sound, instead of a more natural uncompressed one.
Old 13th March 2022
  #15
Here for the gear
 
🎧 5 years
Hey all.

I have been trying to fix one of my 501s as the limiter threshold is stuck on full blast and turning the knob does nothing.

So I opened up both of my units (grey push-button) and wow are they different. One has a weird little daughter board in the middle left of the PCB, the other has an extra trim right on the middle of the PCB. I have figured out the right top trim controls the limiter level, and the left bottom trim adjusts the ratio somehow. I have no idea what the other two trims do. They don’t seem to change anything sonically.

Anyway. I am attaching photos so you can see both revs.
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Question about Symetrix 501 (Compressor)-18c39973-42f3-42d5-a259-bba239ea0130.jpeg   Question about Symetrix 501 (Compressor)-bf8b948f-934c-4492-a0f0-0cc4485c151a.jpeg  
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