I want to put 2 GSSL compressrs in 1box. The question is about powering them - I feel that I don't need a second power transformer, but do I need to solder regulators and all the stuff on the second pcb (so I make parallel connections from transformer to both pcbs) or I can take voltages from one of the boards (so I don't need to build second voltage regulators section). And btw I'll need a 40VA toroid instead of 20VA, am I right?
2 GSSLs in one box
- Thread starter Ilya
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Help Support GroupDIY Audio Forum:
Infernal_Death
Well-known member
Well depends on the voltage regulators but if you use 1A versions you should be on the safe side to power 2 complete units. Don't know the power consumption of a SSL but shouldn't be more than 0.5A (wait for somebody to confirm this).
Personally i would use voltage regulators on both pcbs and just use a stronger transformer to power them both. Voltage regulators aren't that expensive and if you have a pair of regulators for each of the boards you don't need to "drive" them too hard and thus don't need a headsink.
I am not sure but it could be that if you power both SSL's from one set of regulators you may need heatsinks and the regulators on the ssl board don't have enough space for heatsinks so you would need to mount the regulators off board.
Oh and have you thought about how to mount both SSL's in one case ? Especially on the frontpanel it should get very tight. You want to skip the meters ?
Flo
Personally i would use voltage regulators on both pcbs and just use a stronger transformer to power them both. Voltage regulators aren't that expensive and if you have a pair of regulators for each of the boards you don't need to "drive" them too hard and thus don't need a headsink.
I am not sure but it could be that if you power both SSL's from one set of regulators you may need heatsinks and the regulators on the ssl board don't have enough space for heatsinks so you would need to mount the regulators off board.
Oh and have you thought about how to mount both SSL's in one case ? Especially on the frontpanel it should get very tight. You want to skip the meters ?
Flo
Haven't thought about frontpanel mounting, but I definitely don't want to skip any of meters. It would be a 2U (maybe 3U) case for sure. I wanna collect all parts and then decide the final composition of components. Maybe I would decide to place each unit in separate box.
And are you sure that when I power both units from separate regulators there won't be any voltage shifts or something like that between compressors? I may be wrong, if so, correct me, please :roll:
And are you sure that when I power both units from separate regulators there won't be any voltage shifts or something like that between compressors? I may be wrong, if so, correct me, please :roll:
Kev
Well-known member
one power transformer
one larger Bridge Rectifier
then go to both PCBs minus the on board bridge rectifier with DC.
Use the pads for the bridge rectifier as a new DC power in to the PCBs
one larger Bridge Rectifier
then go to both PCBs minus the on board bridge rectifier with DC.
Use the pads for the bridge rectifier as a new DC power in to the PCBs
1A will do
Kev
Well-known member
yeah
I amp should be fine
BUT
you may end up choosing a unit that is convenient to mount rather than just based on electrical spec.
If you were to make a PCB to mount both the transformer anfd Rectifier than there may be a few choices PO4 and WO4 ... look at some of my boards and you will see my typical round and square units I use. The GSSL has the small round unit.
BUT
if you are to use a toroid and the single bolt to the chasis mounting then it might be easy to use a rectifier with a single hole in the centre as well. Usually quite big but occassionally you can find smaller versions of these at the lower rating.
I amp should be fine
BUT
you may end up choosing a unit that is convenient to mount rather than just based on electrical spec.
If you were to make a PCB to mount both the transformer anfd Rectifier than there may be a few choices PO4 and WO4 ... look at some of my boards and you will see my typical round and square units I use. The GSSL has the small round unit.
BUT
if you are to use a toroid and the single bolt to the chasis mounting then it might be easy to use a rectifier with a single hole in the centre as well. Usually quite big but occassionally you can find smaller versions of these at the lower rating.
Mark Burnley
Well-known member
[quote author="Kev"]one power transformer
one larger Bridge Rectifier
[/quote]
Yep.
I've just done this with a stereo 1176. I built a board with bridge rectifier and caps from a single toroid. Then sent +Ve and -Ve and 0V to Channel 1 and Channel 2. I removed the 4 rectifier diodes off each board.
Things can act a bit weird running two rectifiers off one transformer. I also added series resistors and 220uF capacitors in each sub-feed rail. The resistors have taken the strain off the 7824 and zener regulators.
:thumb:
Mark
one larger Bridge Rectifier
[/quote]
Yep.
I've just done this with a stereo 1176. I built a board with bridge rectifier and caps from a single toroid. Then sent +Ve and -Ve and 0V to Channel 1 and Channel 2. I removed the 4 rectifier diodes off each board.
Things can act a bit weird running two rectifiers off one transformer. I also added series resistors and 220uF capacitors in each sub-feed rail. The resistors have taken the strain off the 7824 and zener regulators.
:thumb:
Mark
> Can you suggest any models of the rectifier?
MUST be rated more than the -transformer-.
What is the raw DC voltage, about 50V total? Then a 50V rectifier is marginal. These days silicon voltage is cheap, and rectifiers are cheaper by the dozen (or 10-bag) so go wild and order enough 400V rectifiers for several projects.
Since you don't need even 1A, gyraf is generally correct. However Kev has a point: sometimes you pick a transformer that is convenient (or cheap) that happens to be "oversized" electrically. If a 2A transformer falls into the project and fits perfect, use 2A rectifier.
The 1A rectifier will work, maybe for a very long time. But at start-up the peak current is all about the transformer, not the load. If the starting surge is too high, it will start 1,000 times or 100 times and then crap-out from repeated stress. And sometimes, rectifiers crap-out dead-short, setting your transformer or line cord on fire (or blowing the fuse you should have!).
It is possible to calculate the exact theoretical surge current, but an "oversize" rectifier is cheaper than the value of your time to do the math. Go at least as high as your transformer, round-up, and look to see if the next larger Amp rating is just pennies more cost.
When I was building and rebuilding power supplies daily, I kept piles of 400V 4A rectifiers handy. Even for 20V 0.05A jobs.
MUST be rated more than the -transformer-.
What is the raw DC voltage, about 50V total? Then a 50V rectifier is marginal. These days silicon voltage is cheap, and rectifiers are cheaper by the dozen (or 10-bag) so go wild and order enough 400V rectifiers for several projects.
Since you don't need even 1A, gyraf is generally correct. However Kev has a point: sometimes you pick a transformer that is convenient (or cheap) that happens to be "oversized" electrically. If a 2A transformer falls into the project and fits perfect, use 2A rectifier.
The 1A rectifier will work, maybe for a very long time. But at start-up the peak current is all about the transformer, not the load. If the starting surge is too high, it will start 1,000 times or 100 times and then crap-out from repeated stress. And sometimes, rectifiers crap-out dead-short, setting your transformer or line cord on fire (or blowing the fuse you should have!).
It is possible to calculate the exact theoretical surge current, but an "oversize" rectifier is cheaper than the value of your time to do the math. Go at least as high as your transformer, round-up, and look to see if the next larger Amp rating is just pennies more cost.
When I was building and rebuilding power supplies daily, I kept piles of 400V 4A rectifiers handy. Even for 20V 0.05A jobs.
Svart
Well-known member
I second PRR on buying and using a lot of the same rectifier. when you start to layout your own designs, this makes it a whole lot easier since you know what you are working with and may have the libraries built up. I can't stand how the other designers at work use whatever they have lying around or whatever cost the least. always causes headaches... but i digress..
:green:
:green:
Ok, I have not followed these recommendations as I was not able to find this thread last night...
And I just hooked up two complete boards and split the AC.
now, what I am curious about is this, I believe I am having a noise floor issue very very similar to what I was having with the pultec in that my noisefloor has shot way up to -50db and it was much lower than that with just one channel, at least I am pretty sure, I have to unplug one channel tonight and and retest, but it wasn't -50db that' for sure.
I 100% duplicated the other channel I had and everything works 100%, tracks 100%, sounds 100%. Just really really NOISY.
So, has anybody crammed two ssl's into one chassis and did you have to
do anything special on the grounding different? right now they are wired as if they were two mono channels in seperate chassis, all except the Y on the ac (so they both get power.)
And I just hooked up two complete boards and split the AC.
now, what I am curious about is this, I believe I am having a noise floor issue very very similar to what I was having with the pultec in that my noisefloor has shot way up to -50db and it was much lower than that with just one channel, at least I am pretty sure, I have to unplug one channel tonight and and retest, but it wasn't -50db that' for sure.
I 100% duplicated the other channel I had and everything works 100%, tracks 100%, sounds 100%. Just really really NOISY.
So, has anybody crammed two ssl's into one chassis and did you have to
do anything special on the grounding different? right now they are wired as if they were two mono channels in seperate chassis, all except the Y on the ac (so they both get power.)
strangeandbouncy
Well-known member
I have 2 G-SSL's, and only one mains transformer. Ever since I blew a black hole in the end of my finger messing about with a Fender Twin(DOH!), i am petrified of high voltages, dc and ac. Hence I built a 15-0-15Vac transformer into one very sturdy die-cast box, with binding posts for connection. Now, I don't have to risk anything. It is plenty big enough for 2 G-SSL's and anything else i am working on.(Currently some Mic-pre's with Neve trannies and Fabio's 2@5@2@0's). I have absolutely NO noise issues. Sorry, I can't help here. Whatever you do, Please Make Sure That Everything is PROPERLY Earthed. And NOT via AUdio Cables! i am no expert, but you cannot be careful enough in my book. Think at least TWICE before powering up. COver your eyes, Goggles are good, a sheet of perspex placed over your project AND goggles even better. Don't get carried away by the heat of the moment. Both of my G-SSL's are super quiet btw.
Someone please correct me if my advice is NOT Sound or incomplete!
Be careful out there . . . .
ANdyP
Someone please correct me if my advice is NOT Sound or incomplete!
Be careful out there . . . .
ANdyP
smallbutfine
Well-known member
From all i know, no audio manufacturer uses more than one rectifier/regulator section per voltage if he has to power some identical boards. I think you get a phase shifting when the ac comes to the single rectifiers and they will interact in the regulation process giving less good results...(ehem...confused :? ?)
(not really sure about this, just a thought...)
Nevertheless i have seen some psu's using a second rectifier in serial (for a worst case failure?), but not paralleling...so that if the first rectifier fails, the powered circuit is saved from ac and the fuse saves the transformer (in the best case :grin: ) from the short and at last the whole circuit before the second rectifier fails...(maybe a good idea for manufacturers who calculate their parts *very close* to the needs)
hope this makes enough sense...i should drink some coffee and get the pocket translator before answering questions like this....and probably reading Halliday/Resnicks "physics" again...
Martin
EDITED: sorry, wrote regulator instead of rectifier, corrected...was late this night...
(not really sure about this, just a thought...)
Nevertheless i have seen some psu's using a second rectifier in serial (for a worst case failure?), but not paralleling...so that if the first rectifier fails, the powered circuit is saved from ac and the fuse saves the transformer (in the best case :grin: ) from the short and at last the whole circuit before the second rectifier fails...(maybe a good idea for manufacturers who calculate their parts *very close* to the needs)
hope this makes enough sense...i should drink some coffee and get the pocket translator before answering questions like this....and probably reading Halliday/Resnicks "physics" again...
Martin
EDITED: sorry, wrote regulator instead of rectifier, corrected...was late this night...
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