Already have the kit.....but I think I will do Sissysit first, bought required SITS from Pras....before its over with I will build both. I have entirely too many projects going! 2 preamps, two power amps covering work table now!!! Plus "part boxes" for numerous others. Wayne's 2018 pre, DCG3 pre and Sissysit first....F7 clone needing chassis/sinks and ditto J2 clone, boxes of several others still collecting, BBA3 mono blocks, F4, Vfet etc. Yes, I am a Pass horder.
Russellc
For those cheapskates like me who thought about shoehorning one of these into a Deluxe 4 from the store (and worrying about cooling by fans later) I think it is the case that the board as configured, with the outputs in the designated spots, doesn't actually fit in the chassis using the UMS predrilled holes. I could be wrong, but I've fiddled with it for a bit, and it appears that the M25 in the Deluxe 4 (300mm) chassis would require flying leads on the board to one of the (repositioned) output fets, if avoiding drilling and tapping are your priorities.
The 400 mm deep (non deluxe) chassis is same depth as Deluxe 5. A while back, they provided a member with one pre drilled, but he had to find 4 be others as it required 5 to be ordered. Don't know if it is a "thing" now or not, and if not if they would do another 5. Anyway, just drilling and tapping only the heat sinks isn't that big of a deal.
Russellc
I have the boards and a few amps in deluxe 4, I will have a look. For my $$$, I had as soon just go with Deluxe 5.
Russellc
Russellc
I had a Deluxe 5 years ago, probably for an F4 that I had planned, but sold the parts and the chassis. Mistake. If someone is going to read this forum on an ongoing basis, it's probably best never to sell any parts that are Pass related, or that might possibly be Pass related in the future.
well , it's always possible that I made a mistake, but it looked as mosfets are well positioned on half height row
Ach, I was looking at the wrong row. Of course you didn't make a mistake. 😉
Now comes my least favorite part - desoldering the Sissy parts and installing the M25 parts
Speaking of parts, I have somehow lost my Q1 and Q2, the BD139-140s. I know I can find some in the basement, but do I need to match them?
For paralleling devices, would the entire output stage need to be paralleled, so that each N-P pair has its own optocoupler? Without degeneration, it would seem that the only way to effectively share current between parallel devices - which cannot be matched perfectly - is to control the bias points of each N-P pair individually.
wouldn't play with that
don't use force, use a bigger hammer ........ in other words - if you need more power, build bigger amp
this one is pretty much already insane - ok , it is 25W/8R , but on 4R load , it is 50W of which 40 is in A Class
don't use force, use a bigger hammer ........ in other words - if you need more power, build bigger amp
this one is pretty much already insane - ok , it is 25W/8R , but on 4R load , it is 50W of which 40 is in A Class
I don't plan on it, it was just a matter of curiosity - I noted that there was at least one prototype in the F4 Beast thread that used parallel IRFP devices without degeneration to avoid having to use the hockey pucks, and this seemed like one way to add some reliability. The little hall sensors and optocouplers would add up $$ though in a paralleled design.
I wouldn't parallel them in any way without source resistors
having biasing network for each parallel pair could be just another recipe for disaster, at least as it looks for me
disclaimer - someone smarter maybe is having a way for that, but I'm chicken
pucks are way to go, for another Berserking level
having biasing network for each parallel pair could be just another recipe for disaster, at least as it looks for me
disclaimer - someone smarter maybe is having a way for that, but I'm chicken
pucks are way to go, for another Berserking level
Has anyone done a SissySit-Zilla yet? At least +/– 30V on the rails, 2.5 to 3 Amps bias?
Though we do seem to be heading into SIT-Zilla territory with the Singing Bush discussions.
Though we do seem to be heading into SIT-Zilla territory with the Singing Bush discussions.
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