That seems like a very good way to complete your projects. I don't have the patience to do it on paper first! 
The Modushop enclosures are very attractive, your build will be gorgeous.
A question - do you think there will be any hum/grounding issues making it in 3 enclosures? I am wondering because of a turntable's separate grounding wire. You might need to bring the grounds together, but you won't know until it's built.
Taking with Wayne about grounding he suggests that you insulate and float all the signal connections from the chassis in the beginning. (Obviously not the Mains safety earth...) Sometimes it's very quiet that way. That is how it looks in your diagram that you are planning it, hopefully it's successful.
My Pearl (original) has all the signal connections floating, the turntable grounding lead as tied to the chassis as well as the center grounds on the PCB
As for bleeders, I see no reason why you can't use them. I have many of the 2.2k 3W resistors left over from my F5 build, and will use them in my Pearl 2 supply. You could also use a different (more ohm) value with lesser dissipation if you have those on hand. It's not a critical value.
The Modushop enclosures are very attractive, your build will be gorgeous.
A question - do you think there will be any hum/grounding issues making it in 3 enclosures? I am wondering because of a turntable's separate grounding wire. You might need to bring the grounds together, but you won't know until it's built.
Taking with Wayne about grounding he suggests that you insulate and float all the signal connections from the chassis in the beginning. (Obviously not the Mains safety earth...) Sometimes it's very quiet that way. That is how it looks in your diagram that you are planning it, hopefully it's successful.
My Pearl (original) has all the signal connections floating, the turntable grounding lead as tied to the chassis as well as the center grounds on the PCB
As for bleeders, I see no reason why you can't use them. I have many of the 2.2k 3W resistors left over from my F5 build, and will use them in my Pearl 2 supply. You could also use a different (more ohm) value with lesser dissipation if you have those on hand. It's not a critical value.
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The cinch connectors are insulated, so ground is floating. Both channel boxes are connected to the PSU box by a shielded cable, with shield going to chassis at both ends.
I have heard about ground loops (newbie, so no actual experience with them), but assume these will not occur because there is only one path from anywhere to earth (i.e. no "loop"). I was considering adding a small switch in each channel box to optionally connect signal ground to chassis (in the channel box) but decided not to as it would introduce potential ground loops.
As you said, I'll have to wait till it's built. Perhaps it will be best to ground the turntable at the power supply box?! We'll see.
Albert
PS I think I might as well add the 2k2 bleeders. I also have some left over!
The 35 amp rectifier is a ground-loop breaker, to isolate the PSU/circuit from the mains noise, but still big enough to pass a bunch of current if there is an actual mains fault. You only need one, attached to the PSU ground, although having another might be useful, if you have hum problems in the circuit chassis.
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The bleeders are there to discharge the capacitors when the system is switched off. I only just realised today that they were not in the original schematic (see my earlier post).
I understand that you need a total of 3 bridge rectifiers:
- 1 for the - rail
- 1 for the + rail
- 1 for the chassis/ground connection
I will use 200V/35A throughout, but according to the Pearl II paper the two rail bridge rectifiers can be smaller (1A) versions.
The F4/F5 power supplies use a thermistor instead of a brdige rectifier to link ground to earth/chassis. Could show that Nelson and Wayne each have a different way of solving the same problem. Perhaps one is better suited for high-current circuits and the other better for low-current circuits?
==> Wayne/Nelson/someone_else: is that the case?
Hope this helps.
Albert
35A for the PSU is sever overkill, and, more importantly, you can't really get high-speed, soft-recovery diodes in packaged bridges.
As for the thermistor vs. diode bridge question, my understanding is (if I remember the conversation with Wayne correctly) is that the bridge is quieter, and more suited to a line-level device.
As for the thermistor vs. diode bridge question, my understanding is (if I remember the conversation with Wayne correctly) is that the bridge is quieter, and more suited to a line-level device.
Hi 6L6,
I read that nAr used a packaged bridge: http://www.diyaudio.com/forums/pass-labs/156397-pearl-two-51.html#post2302517 Could very well be that the one he uses is a lot better than the one I use, but I have no idea.
(I just saw his is cheaper. Cheaper is always better!)I just now checked the specs of the one nAr uses http://www.diodes.com/datasheets/ds21227.pdf and the one I am using http://www.vishay.com/docs/88612/gbpc12.pdf but I have no idea what I am looking for so am no wiser.
I will use what I have and read some more about the subject. The good thing about DIY is you can always upgrade
Interesting BTW about the bridge vs. thermistor grouding. Again something to read about in order to understand why one is better suited for some circuits than the other.
Nar - a question... Where are you inserting the power from your regulator? (From the regulator board to the Pearl 2 circuit board)
Also, what components native to the Pearl 2 board are you removing?
I want to try a discrete regulator in the future, and am interested how it could be implemented.
Also, what components native to the Pearl 2 board are you removing?
I want to try a discrete regulator in the future, and am interested how it could be implemented.
Hi 6L6,
I read that nAr used a packaged bridge: http://www.diyaudio.com/forums/pass-labs/156397-pearl-two-51.html#post2302517 Could very well be that the one he uses is a lot better than the one I use, but I have no idea.
I just now checked the specs of the one nAr uses http://www.diodes.com/datasheets/ds21227.pdf and the one I am using http://www.vishay.com/docs/88612/gbpc12.pdf but I have no idea what I am looking for so am no wiser.
I will use what I have and read some more about the subject. The good thing about DIY is you can always upgrade
Interesting BTW about the bridge vs. thermistor grouding. Again something to read about in order to understand why one is better suited for some circuits than the other.
In actual PSU I just throwed out some basic components. If you can, try some high speed audio grade diodes, better, for the recovery question, use some soft ones if datasheet specifies, or use some RC snubbers across.
For the Ground component, yes try the diode bridge, should fit better than a thermistor in that small signal unit
That's pretty simple : for now PSU is unreg. and feeds the 2 channels. The umbilical has 4 wires : V+ GND V- and EARTH to chassis. Audio Ground floats from chassis.
When I'll implement the new regulation, I'll have one PSU from each channel. So umbilical will go to 7 wires : the 2 PSU + EARTH. Now, for good performance, I also will remove the 7824 and 7924. On board, old + Unreg and + Reg points will be linked with a jumper.
A better thing would be add the the regulation part of the boards I show in my previous post, to get regs closer to boards, and the transformer / diodes / 1st round of capacitors away from the circuit. The hi-fi-2000 chassis I have is too small for this, however, so I'll end up having the regulations a couple of feets away. I don't think it will degrade things however, as Pearl II has built in RC filters on board, it should stay pretty stable
As I said earlier, a good discrete reg. should enhance sound quality. The utmost is maybe the shunt reg path, like Salas ones which seem damn good. Should bring you the "gooood soooound", even if you must be ready to waiste about 10 times the consumed power of the circuit itself in the shunt reg. But it should be fine, as Pearl II isn't that greedy, so maybe a good thing to try ... As I had total satisfaction with the UGS PSUs, I was so tempted to use them thorough
Best,
nAr
Thanks 6 ,
there is a lot of buzz about alternatives ,but I need to keep it simple and do as I'm told .
1 rectifier is what I'll use . This is not to say I'm dismissing the input of Nar and Albert ,merely that I need to work within my limitations . I can only follow one design, but it is exciting to see how much fun others, with more knowledge , are having . It keeps me going through my mistakes. I'll get there someday .
Thanks all for your input , Rich
Yes, those are the '1 amp' rectifiers. There is one bank of discrete MUR820 in the (+) rail, forming a bridge, giving full-wave rectification for that rail.
There is an identical assemble in the (-) rail, so there are 2 bridges necessary to rectify the AC from the secondary side of the transformer, and make the V+/V- power supply.
The big single-package 35A bridge is not being used for rectification in the PSU. It is there to isolate the signal ground from the chassis from the Mains earth. The big bridge looks like a floating ground (and hopefully quiet) to the signal, but if there is a genuine problem (a mains short circuit or other bad problem) in the the PSU, it will still conduct the mains voltage to earth, keeping the chassis from going 'hot'
How critical is the Wattage or VA ? ...... Am I creating too many problems
using this .... ?
MULTICOMP|MCFE050/25|TRANSFORMER, 50VA, 2 X 25V | Farnell United Kingdom
or this .... http://uk.farnell.com/block/rk40-22/transformer-40va-2-x-22v/dp/1419543
using this .... ?
MULTICOMP|MCFE050/25|TRANSFORMER, 50VA, 2 X 25V | Farnell United Kingdom
or this .... http://uk.farnell.com/block/rk40-22/transformer-40va-2-x-22v/dp/1419543
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