SSL Clone compressor ratio measurements
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SSLtech
Well-known member
Sounds logical to me... if you want two channels processed similarly then you'd want the same ratio as a fundamental requirement, don'tcha think?
-If you wanted different settings on the two chanels, you'd probably not want the compressor in stereo... that's my take. (Oh, I konw there could be a theoretical argument made against it, but I reckon that the likelihood of someone acidentally setting the switches wrong outweighs the need to acommodate such an unlikely use)
YMMV
Keith
-If you wanted different settings on the two chanels, you'd probably not want the compressor in stereo... that's my take. (Oh, I konw there could be a theoretical argument made against it, but I reckon that the likelihood of someone acidentally setting the switches wrong outweighs the need to acommodate such an unlikely use)
YMMV
Keith
while the compressor is working, i set the reference level....
at 2:1 when i raise it 10dB, i get 4dB of Rise
at 4:1 when i raise it 10dB, i get 2dB of Rise
at 10:1 when i raise it 10dB, i get 0dB of Rise.. and when i raise it further than 10db (about 14dB and higher)... the output acutally goes down a little. is this what you mean by goes "Past-Infinity" Keith?
at 2:1 when i raise it 10dB, i get 4dB of Rise
at 4:1 when i raise it 10dB, i get 2dB of Rise
at 10:1 when i raise it 10dB, i get 0dB of Rise.. and when i raise it further than 10db (about 14dB and higher)... the output acutally goes down a little. is this what you mean by goes "Past-Infinity" Keith?
SSLtech
Well-known member
[quote author="quadwould"]while the compressor is working, i set the reference level....
at 2:1 when i raise it 10dB, i get 4dB of Rise
at 4:1 when i raise it 10dB, i get 2dB of Rise
at 10:1 when i raise it 10dB, i get 0dB of Rise.. and when i raise it further than 10db (about 14dB and higher)... the output acutally goes down a little. is this what you mean by goes "Past-Infinity" Keith?[/quote]
Zak Lee.
Your ratios are too high, a little resistive adjustment will bring pleasure.
(you could also add a switch to give you 2:1/4:1/10:1 in one position and 2.5:1/5:1 and infinity in the other, if you so wish) :thumb:
Keef
at 2:1 when i raise it 10dB, i get 4dB of Rise
at 4:1 when i raise it 10dB, i get 2dB of Rise
at 10:1 when i raise it 10dB, i get 0dB of Rise.. and when i raise it further than 10db (about 14dB and higher)... the output acutally goes down a little. is this what you mean by goes "Past-Infinity" Keith?[/quote]
Zak Lee.
Your ratios are too high, a little resistive adjustment will bring pleasure.
(you could also add a switch to give you 2:1/4:1/10:1 in one position and 2.5:1/5:1 and infinity in the other, if you so wish) :thumb:
Keef
chrissugar
Well-known member
quadwould
Read what I posted about this at page four in this thread:
http://www.groupdiy.com/index.php?topic=944&postdays=0&postorder=asc&start=45
chrissugar
Read what I posted about this at page four in this thread:
http://www.groupdiy.com/index.php?topic=944&postdays=0&postorder=asc&start=45
chrissugar
[quote author="SSLtech"]
Zak Lee.
Your ratios are too high, a little resistive adjustment will bring pleasure.
(you could also add a switch to give you 2:1/4:1/10:1 in one position and 2.5:1/5:1 and infinity in the other, if you so wish) :thumb:
Keef[/quote]
yep a little adjustment is right. 120K works. its suprising how fine a line there is between 10:1 and Infinity/reverse ... i wonder if one could alter the resistive setting to make the 3 ratios something like [ 5:1, 20:1 and Ducking] that would be interesting. the 5:1 would be nice for alot of applications whena little punh is needed.. (sorta DBX like) the 20:1.. Slam mode (all buttons) comes to mind.... and Ducking.. well for cool effects...... hmmmmm :idea:
cheers Chrissugar for that reminder. :guinness:
Zak Lee.
Your ratios are too high, a little resistive adjustment will bring pleasure.
(you could also add a switch to give you 2:1/4:1/10:1 in one position and 2.5:1/5:1 and infinity in the other, if you so wish) :thumb:
Keef[/quote]
yep a little adjustment is right. 120K works. its suprising how fine a line there is between 10:1 and Infinity/reverse ... i wonder if one could alter the resistive setting to make the 3 ratios something like [ 5:1, 20:1 and Ducking] that would be interesting. the 5:1 would be nice for alot of applications whena little punh is needed.. (sorta DBX like) the 20:1.. Slam mode (all buttons) comes to mind.... and Ducking.. well for cool effects...... hmmmmm :idea:
cheers Chrissugar for that reminder. :guinness:
dufo
Well-known member
[quote author="Emperor-TK"]EUREKA! This thread helped me solve my GSSL problem! My ear told me there was something wrong with my build. There was distortion, particularly on the lower frequencies. Also, the compressor just wasn't responding right. It just sounded bad, and I couldn't quite put my finger on it. It was a choked and strained sound.
After buying Audiotester, I went to work. I benchedmarked the GSSL vs. my RNC and Behringer compressors using the FFT and looking at the relative harmonic to fundamental ratios. The GSSL was definitely putting out more distortion than the others. Also, the RNC in "normal" mode has a similar amount of low end distortion. And I already knew that I hated that compressor for any low end material (except in "super nice" mode). So my ears weren't lying. Still though, my GSSL didn't sound as good as the RNC, which has too much low end distortion, but doesn't sound choked.
The solution was in the VCA inputs, as discussed in this thread. I also used Audiotester to measure the compressors response as described by SSLtech. 2:1 gave me 3.5:1, 4:1 gave me infinity, and 10:1 gave me an inverse response (greater than infinity). Originally, I had used the DBX c1252h2 VCA's. I changed those out to THAT2180LA's (thanks Zach) and the distortion went away. I played around with the resistor feeding the negative input of the TL072 just before the CV inputs (as suggested by Steffen). I needed a 122K resistor here and I am now getting normal ratios. No more choked response!
Can anyone comment on what the pro's and cons might be of changing the input resistor to the op-amp vs. the input resistors to the VCA CV's? The one thing I can see is that the make-up gain won't be effected with the op-amp input resistor (which is good I think). On the down side, I now need to tweak the resistor feeding the meter so that it shows the correct amount of gain reduction, but that should be easy.
Anyway, I am VERY excited now. Cheers to Jakob, Steffen, SSLtech, Gus, and everyone that has shared their general expertise and experience on the GSSL.
:guinness: :sam: :guinness: :sam: :green: :thumb:
-Chris[/quote]
Sorry for the stupid question, but...
Ok, so you say you had to re calibrate the GR on the meter.
Say if your threshold is set to show 8db of GR, as Keith suggests...
Then at 2:1, you increase the input by 10db, ideally for a 5db increase at output...
the meter should show 13db of GR ?? Is this the way to calibrate it ??
Trying to understand.
After buying Audiotester, I went to work. I benchedmarked the GSSL vs. my RNC and Behringer compressors using the FFT and looking at the relative harmonic to fundamental ratios. The GSSL was definitely putting out more distortion than the others. Also, the RNC in "normal" mode has a similar amount of low end distortion. And I already knew that I hated that compressor for any low end material (except in "super nice" mode). So my ears weren't lying. Still though, my GSSL didn't sound as good as the RNC, which has too much low end distortion, but doesn't sound choked.
The solution was in the VCA inputs, as discussed in this thread. I also used Audiotester to measure the compressors response as described by SSLtech. 2:1 gave me 3.5:1, 4:1 gave me infinity, and 10:1 gave me an inverse response (greater than infinity). Originally, I had used the DBX c1252h2 VCA's. I changed those out to THAT2180LA's (thanks Zach) and the distortion went away. I played around with the resistor feeding the negative input of the TL072 just before the CV inputs (as suggested by Steffen). I needed a 122K resistor here and I am now getting normal ratios. No more choked response!
Can anyone comment on what the pro's and cons might be of changing the input resistor to the op-amp vs. the input resistors to the VCA CV's? The one thing I can see is that the make-up gain won't be effected with the op-amp input resistor (which is good I think). On the down side, I now need to tweak the resistor feeding the meter so that it shows the correct amount of gain reduction, but that should be easy.
Anyway, I am VERY excited now. Cheers to Jakob, Steffen, SSLtech, Gus, and everyone that has shared their general expertise and experience on the GSSL.
:guinness: :sam: :guinness: :sam: :green: :thumb:
-Chris[/quote]
Sorry for the stupid question, but...
Ok, so you say you had to re calibrate the GR on the meter.
Say if your threshold is set to show 8db of GR, as Keith suggests...
Then at 2:1, you increase the input by 10db, ideally for a 5db increase at output...
the meter should show 13db of GR ?? Is this the way to calibrate it ??
Trying to understand.
dufo
Well-known member
Anyone ?? :grin:
Emperor-TK
Well-known member
Dufo, you basically need to have a way to measure both your input and output voltages/volumes. There are several ways to do this (Audiotester, Wavelab, scope, etc). The last time I did it I just used my EMU1820M audio card. I used the built in mixer to send a sine wave into the SSL and then back into the audio card. Peak meters were availible on both inputs and outputs. I set the makeup gain to get unity at -50dBFS and stepped up in 2dB increments and made notes of the output level. I did this for three different thresholds. This pretty much maps out the compressor's steady-state response, i.e. the ratio and knee shape. Here is a plot of the data in Excel:
To trim the meter, find a setting where you know the difference between the input and output and trim the feeder resistor so that your meter matches that value. i.e., if you are sending -10dBFS into the ssl and getting -15dBFS out, trim the feeder resistor until your meter reads "5". It doesn't matter what the input, threshold, attack, release, or ratio is, but you do need to make sure that the makeup is at unity (otherwise you are getting a constant offset for both below threshold and above threshold signals, and this offset doesn't show up on the GR meter).
Hope this helps,
Chris
To trim the meter, find a setting where you know the difference between the input and output and trim the feeder resistor so that your meter matches that value. i.e., if you are sending -10dBFS into the ssl and getting -15dBFS out, trim the feeder resistor until your meter reads "5". It doesn't matter what the input, threshold, attack, release, or ratio is, but you do need to make sure that the makeup is at unity (otherwise you are getting a constant offset for both below threshold and above threshold signals, and this offset doesn't show up on the GR meter).
Hope this helps,
Chris
dufo
Well-known member
Thanks alot Chris!
Im trying to get my head round that,
In the meantime, Ill just feed the in level amount you suggested, and change resistance till I get 5 on the meter.
Actually understanding may take a while! :grin:
Thanks again.
Im trying to get my head round that,
In the meantime, Ill just feed the in level amount you suggested, and change resistance till I get 5 on the meter.
Actually understanding may take a while! :grin:
Thanks again.
dufo
Well-known member
Doing the ratio test, after Stefens resistor mod, I got the following
2:1 -Increase input 10dB, output increases by 4.5dB.
4:1 -Increase input 10dB, output increases by 2.75dB.
10:1 -Increase input 10dB, output increases by 1dB.
This was with 120K replacing the 100K.
How do you translate those results to actual ratio's?
Has anyonge got any closer than this? Is it worth trying to get closer? thanks
2:1 -Increase input 10dB, output increases by 4.5dB.
4:1 -Increase input 10dB, output increases by 2.75dB.
10:1 -Increase input 10dB, output increases by 1dB.
This was with 120K replacing the 100K.
How do you translate those results to actual ratio's?
Has anyonge got any closer than this? Is it worth trying to get closer? thanks
deveng
Well-known member
Does anyone know of an inexpensive application that will do plots? I'm specifially looking for one that can ramp a single frequency to plot threshold/ratio settings for compressors. I'd like to verify ratio and threshold settings without doing repeatative set and measure. Too time consuming.
By the way, I have built my version of the S*M*A*R*T C1 and it works like a charm! Uses THAT 2151's and is dual mono and stereo. Used great parts, EAO's, 1% metal film R's, low ESR caps, sealed 24v relays, beefed up power supply with Linear Tech's low-dropout regulators and Hexfreds. Added balanced outputs with NE5532AN's. So far it's spec'd very nicely and all controls appear to be accurate, including threshold! But...I'd like to plot to make sure.
Regards,
Jeff
By the way, I have built my version of the S*M*A*R*T C1 and it works like a charm! Uses THAT 2151's and is dual mono and stereo. Used great parts, EAO's, 1% metal film R's, low ESR caps, sealed 24v relays, beefed up power supply with Linear Tech's low-dropout regulators and Hexfreds. Added balanced outputs with NE5532AN's. So far it's spec'd very nicely and all controls appear to be accurate, including threshold! But...I'd like to plot to make sure.
Regards,
Jeff
peeceebee
Active member
My GSSL with dbx 2151's had the extreme ratios, inverse on 10/1, etc.
About 240R right before the two 1k resistors feeding the vca cv inputs put it just about spot on-
A nice place to add the resistance is at the jumper wire just before the first 1k resistor, next to the 1meg resistor- Don't need to pull the board to try different values-
Now the unit sounds great!
About 240R right before the two 1k resistors feeding the vca cv inputs put it just about spot on-
A nice place to add the resistance is at the jumper wire just before the first 1k resistor, next to the 1meg resistor- Don't need to pull the board to try different values-
Now the unit sounds great!
khstudio
Well-known member
Has anyone ever tested a 'Real" SSL buss comp to see how it responds?
Maybe a dumb question but I?m curious how accurate they are... the current design doesn't look that off from the original so I wonder if they have similar issues & also adjust each unit.
The reason I'm asking is I tried this method on my Distressor, starting @ about -10db gain reduction on the meter to stay away from knee & it was no where near your recommendations for being correct. Am I off here? Anybody ever test other comps to see what they do?
Do you guys find that making these adjustments is really that much of an improvement?
Maybe a dumb question but I?m curious how accurate they are... the current design doesn't look that off from the original so I wonder if they have similar issues & also adjust each unit.
The reason I'm asking is I tried this method on my Distressor, starting @ about -10db gain reduction on the meter to stay away from knee & it was no where near your recommendations for being correct. Am I off here? Anybody ever test other comps to see what they do?
Do you guys find that making these adjustments is really that much of an improvement?
khstudio
Well-known member
[quote author="Peter"]So the closest ratio to the design comes fromm the 2180 la? Better than the 2181? Is the discrepency in ratios soley caused by the vca chosen, or do the percentage of the resistors have a roll to play?
Peter[/quote]
[quote author="mesmer"]The 2181 specs a helluva lot better. How close does it come to meeting the ratios?
Peter[/quote]
Is this true... does the 2181 spec better than the 2180?
Found this earlier in this thread & would like to know since I have both VCA's & don't understand some of the data on the spec sheets.
Peter[/quote]
[quote author="mesmer"]The 2181 specs a helluva lot better. How close does it come to meeting the ratios?
Peter[/quote]
Is this true... does the 2181 spec better than the 2180?
Found this earlier in this thread & would like to know since I have both VCA's & don't understand some of the data on the spec sheets.
martthie_08
Well-known member
You "can" adjust the 2181 to spec better than the 2180, which is pre-trimmed. That said, when using the 2180 you will have to leave some stuff off the board, i.e. the trim pot and some other things. But also with the 2181 there are some adjustments with regards to the 2150, but it is all detailed on the THAT corp. website, have a look at their technical documents. I think some time ago I did a little webpage that details some stuff about the 2181, it might still be around.
And yes, it makes a big difference to adjust the ratios correctly, at least in my world. In fact, my GSSL did not sound too great, when I first got it up running. But it was a combination of different things: hum from AC mains, incorrect ratios, threshold not very well adjusted, cheap caps... in my opinion you really have to take your time with the project, as in: build it up - listen, adjust something - listen, modify - listen. All the info is in the forum or on the manufacturers websites. That said, my unit sounds excellent now, we finished our new album and the GSSL was on the mix bus on 9 out of 12 songs (and we had plenty of options that we auditioned).
Cheers, martthie_08
And yes, it makes a big difference to adjust the ratios correctly, at least in my world. In fact, my GSSL did not sound too great, when I first got it up running. But it was a combination of different things: hum from AC mains, incorrect ratios, threshold not very well adjusted, cheap caps... in my opinion you really have to take your time with the project, as in: build it up - listen, adjust something - listen, modify - listen. All the info is in the forum or on the manufacturers websites. That said, my unit sounds excellent now, we finished our new album and the GSSL was on the mix bus on 9 out of 12 songs (and we had plenty of options that we auditioned).
Cheers, martthie_08
Purusha
Well-known member
I just ordered 25 pcs of THAT 2181LBs for 12 G-SSLs I am building with my friends. Can someone explain in few words what are the precise changes which we need to make to get our G-SSL's ratios working properly with 2181LBs?
Thanks.
Thanks.
Greg
Well-known member
Purusha:
I'm unsure of your question. You simply need to do the procedure described at the beginning of this thread by SSLTech. Do this on one of your SSLs, then just use the new resistor value in the other 11.
I'm unsure of your question. You simply need to do the procedure described at the beginning of this thread by SSLTech. Do this on one of your SSLs, then just use the new resistor value in the other 11.
Purusha
Well-known member
I am just trying to cut corners here :grin:
I will do this when everything is soldered. I was thinking to get some answer like: if you have THAT2181LB than you just change the resistor X with resistor Y and you are set.
I will do this when everything is soldered. I was thinking to get some answer like: if you have THAT2181LB than you just change the resistor X with resistor Y and you are set.
