how noisy is your SSL clone?
- Thread starter Svart
- Start date
Help Support GroupDIY Audio Forum:
svart-
I had a console with unbalanced sends, I used to feed them to line amps for balancing and color and then off to a limiter or whatever. this might not exactly address your specific thing with the gssl, but it will make your big picture a LOT cooler sounding. IF you plan on holding on to that console for a while and dont have a patch bay to patch around using unbalanced sends, you might be stoked if your next few projects were some balancing line amps, that made all the difference for me back in the day.
dave
I had a console with unbalanced sends, I used to feed them to line amps for balancing and color and then off to a limiter or whatever. this might not exactly address your specific thing with the gssl, but it will make your big picture a LOT cooler sounding. IF you plan on holding on to that console for a while and dont have a patch bay to patch around using unbalanced sends, you might be stoked if your next few projects were some balancing line amps, that made all the difference for me back in the day.
dave
Svart
Well-known member
thanks soundguy. that is indeed one of my next projects!
I find it also weird how the group outs are unbalanced but just about everything else IS balanced on this thing.
I'd like to figure out how the console switches between +4 and -10 on the mono channels, maybe i could make that work for the group outs too..?
anyone know an easy way to convert from -10 to +4?
I find it also weird how the group outs are unbalanced but just about everything else IS balanced on this thing.
I'd like to figure out how the console switches between +4 and -10 on the mono channels, maybe i could make that work for the group outs too..?
anyone know an easy way to convert from -10 to +4?
NewYorkDave
Well-known member
Any low-noise op-amp set up for a gain of 4 (12dB) will do the trick.
-10dBV is equal to -8dBU, so boosting to +4dBU requires 12dB of gain.
You can either use a balanced-output stage with a gain of 12dB, or a single-ended 12dB gain stage driving a transformer, to go from -8dBU unbalanced to +4dBU balanced.
-10dBV is equal to -8dBU, so boosting to +4dBU requires 12dB of gain.
You can either use a balanced-output stage with a gain of 12dB, or a single-ended 12dB gain stage driving a transformer, to go from -8dBU unbalanced to +4dBU balanced.
Svart
Well-known member
most of the i/o is driven from tl072/82 or 5532s.. maybe i could up the gain on those outputs? however i don't know what they are running at currently so i'd have to figure that out...
Svart
Well-known member
problem solved.
turns out that it was my own fault. During the build up I asked many questions about how to hook these units up as UN-balanced units. A number of people answered to leave the inverted inputs unconnected(floating). Without testing, I did just that.
Since then, I have studied op-amps and their designs and learned that most op-amps need the unused inputs grounded. I thought about what my problems were.. signal 12db lower than it should have been, having to turn the output to max, having to turn the threshold down really far.. seemed like the input signal was weak. measured the insert sends, they ARE +4, or whatever I set the channel as apparently. the only thing it could be was the input section of the GSSL.
I shunted the inverted inputs to ground.
signal level became normal, makeup is usable at unity now, and best of all, the noise floor is where it seems right, -80db.
so the unit was not noisy, I just had to turn the sucker up too much to get audio and that also amplified the floating input and the noise floor.
cheers!
turns out that it was my own fault. During the build up I asked many questions about how to hook these units up as UN-balanced units. A number of people answered to leave the inverted inputs unconnected(floating). Without testing, I did just that.
Since then, I have studied op-amps and their designs and learned that most op-amps need the unused inputs grounded. I thought about what my problems were.. signal 12db lower than it should have been, having to turn the output to max, having to turn the threshold down really far.. seemed like the input signal was weak. measured the insert sends, they ARE +4, or whatever I set the channel as apparently. the only thing it could be was the input section of the GSSL.
I shunted the inverted inputs to ground.
signal level became normal, makeup is usable at unity now, and best of all, the noise floor is where it seems right, -80db.
so the unit was not noisy, I just had to turn the sucker up too much to get audio and that also amplified the floating input and the noise floor.
cheers!
Great that you got that one sorted out!
:thumb:
Jakob E.
:thumb:
Jakob E.
DrFrankencopter
Well-known member
FWIW, the one you want to float for un-balanced operation is OUTPUT pin. The SSL has an active balanced output and things will likely get nasty (and toasty) if you drive that into ground.
Cheers,
Kris
Cheers,
Kris
Svart
Well-known member
thanks, I knew enough not to do that at the time! I think when i was asking about grounding unused inputs someone must have thought I meant outputs or something...? dunno, but i hope this experience will help others.
Svart
Well-known member
yeah, I was kinda sweating it and hoping it wasn't a problem with my console.
clintrubber
Well-known member
from Kris:
I was worried about that myself too since my unit will see unbalanced use as well.
However, I don't think shorting the inverting output will do much harm - the 5532 can take it and since this output doesn't serve as the input for the other output amp at the same time (it's just the other way around) I think all will be OK. Leaving it unconnected will of course be 'better' (less current consumption etc) but as long as the supply is OK & firm I don't think there will be a difference in sound.
Peter
I was worried about that myself too since my unit will see unbalanced use as well.
However, I don't think shorting the inverting output will do much harm - the 5532 can take it and since this output doesn't serve as the input for the other output amp at the same time (it's just the other way around) I think all will be OK. Leaving it unconnected will of course be 'better' (less current consumption etc) but as long as the supply is OK & firm I don't think there will be a difference in sound.
Peter
Svart
Well-known member
hmmm, i'm sure just leaving the inv output open and floating won't have any effect on the sound will it?
clintrubber
Well-known member
Correct, open is OK
...but shorting the inv. output wouldn't give problems either (e.g. in case you're using TRS-jacks and a mono jack plug).
Shorting outputs like this happens all the time (for instance in mixers like the Mackie MS1202: the output is balanced on TRS but eats TS-jacks as well. The series output resistor takes care of it).
Hope I didn't make it confusing ! :wink:
Bye,
Peter
Still, it's a good idea to leave the non-used output hanging in stead of grounding it...
Jakob E.
Jakob E.
Svart
Well-known member
thanks Gyraf, was planning on leaving those floating anyway.
T
tubejay
Guest
Why not just build it with balanced i/o, and then make four cables that tie the low and ground pins together? That way if you upgrade to a balanced system in the future, all you have to do is change cables? Doesn't making a balanced to unbalanced connector essentially do the same thing, or does that affect the input/output levels?
Luny Tune
Well-known member
Hi there.
Great forum! Great bunch of helpful people. I hope I'll be able to help in the future too. I'm an experienced engineer, but new to building my own equipment, therefore...:
My desk has unbalanced mixbus inserts meant to be used with insertcables like this: Tip=Return, Ring=Send. (It's a Soundtracs MIDI PC console)
I will of course not mess with the SSL itself as it's designed as it should be, but at this point I'd like to use it unbalanced.
As far as I can tell by the posts here, what I need to do is to leave a pin on the output unconnected and a pin on the input grounded.
But which pins are you talking about? Which ones are the the inverted ones?
I hope it can all be done with the cable I'm gonna make for use between the unit and the mixbus insert.
Which pins on the input XLR should I short to ground the inverted input?
Which pin on the output XLR should I not connect at all to leave the inverted output floating?
Great forum! Great bunch of helpful people. I hope I'll be able to help in the future too. I'm an experienced engineer, but new to building my own equipment, therefore...:
My desk has unbalanced mixbus inserts meant to be used with insertcables like this: Tip=Return, Ring=Send. (It's a Soundtracs MIDI PC console)
I will of course not mess with the SSL itself as it's designed as it should be, but at this point I'd like to use it unbalanced.
As far as I can tell by the posts here, what I need to do is to leave a pin on the output unconnected and a pin on the input grounded.
But which pins are you talking about? Which ones are the the inverted ones?
I hope it can all be done with the cable I'm gonna make for use between the unit and the mixbus insert.
Which pins on the input XLR should I short to ground the inverted input?
Which pin on the output XLR should I not connect at all to leave the inverted output floating?
Luny Tune
Well-known member
Brilliant! Thanks.
Similar threads
