Building a 5 channel BLS
Right, as part of my ongoing efforts to build my ultimate Hi-Fi/HT rig I need to get 5 channels of unbalanced pre balanced to feed into my active crossovers. As I have a 300VA 55-0-55 traffo and lots of other suitable bits in my spares box, I obviously thought of breaking my PassLabs virginity and building a BLS.
So, the questions-
1) Would I be better building a psu stage for each pair of amps, as per the normal design, or can I upgrade the existing PSU to provide the required power?
2) Is there any benefit in providing more capacitance on the PSU rails, or is 10000uf more than sufficient.
3) I was looking at the Onsemi website a few days ago, and I noticed they have a new range of mosfets, has anyone used them yet? I'm just wondering if they would sound any better.
4) Anyone got any specific component recommendations for the BLS?
Thanks a lot:)
1) 1 psu (in your case regulator; just one toroid right?) per channel is best (the pass transistors gets HOT). Or you can scale it (ZV3.pdf)
2) 10000uF is what I use for C101/102 (really overkill, I know..) and 1000uF for C103-105, else as original , as I recall Nelson recommends to double all C's.
3) try the IRF510 -very nice.
4) 750/1500 ohm: Caddock MP915/930. Good, low impedance C's. Ultrasoft diodes. Elna/DACT I/P selector, DACT attenuators/homebrew with Elma/ 0,1% resistors.
Thanks for the reply K:)
So, I need to build a reg stage for each channel, fair enough, it probably keeps the isolation between channels.
But, do I need the bridge and the big caps per channel, or can I have a big reservoir bank and feed the seperate pass regulators on their own boards. I know what the purist answer would be, but I am not well off at the moment, and I need to be in the Frugalphile (tm) frame of mind!;)
whoops! sorry for late answer, but I didn't notice your reply until now. I would make one (dual) bridge and a pair of bigguns (or better CRC or CLC). Then you make one reg per channel (without b101/b102). I would recommend to toss in a 10-220uF for c101/b102 though.
I would take: toroid, dual rectifiers (StealthTM from Fairchild), CRC (10000uF*/10 Ohm 5W (wirewound)/10000uF*(=Rifa PEH200, 100V), and 1000uF* for C101-106, but this is overkill.
Having a reg for each channel helps to minimize crosstalk between channels.
Project is temporarily on hold due to possible house move, and therefore shortage of funds, but it is high up the list for when I get settled down again.
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