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Old 28th October 2011, 06:15 PM   #21
nar is offline nar
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Neat design and awsome upgrade idea. Lets us know how it works when done

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Old 28th October 2011, 06:45 PM   #22
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I was always unsure about using Peter's boards. Doesn't seem like there is good separation for heat dissipation. I will be interested to see if it feels like the heat is concentrated on your heat sinks with the middle being warmer than the ends. Looking forward to the results as I never went through with the project.
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Old 28th October 2011, 06:49 PM   #23
6L6 is offline 6L6  United States
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Well, the majority of my power devices will be on their own heatsink, connected to the PCB via an umbilical. (or extension wires, if you want to call them that.) I think the stock configuration of his board would be fine if you had one really big linear heatsink.
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Old 28th October 2011, 06:55 PM   #24
nar is offline nar
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Which spacing is there between the mosfets tightening screws ?
Extra wires should do, but careful with unwanted oscilations (long leads)
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nAr
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Last edited by nar; 28th October 2011 at 06:57 PM.
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Old 28th October 2011, 08:55 PM   #25
tmblack is offline tmblack  United Kingdom
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What is the power supply voltages and current requirements?
Looks like R3 needs to be grounded for single-ended operation.
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Old 28th October 2011, 09:06 PM   #26
6L6 is offline 6L6  United States
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PSU will be a variation of 'Zen Vernacular", which is to say 18v+18v 400va, 2 full wave bridges and CRC with about 120,000uf per rail.

Look at an F5 PSU and double the capacitance. That's the template I'm working from.
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Old 29th October 2011, 12:15 PM   #27
qusp is offline qusp  Australia
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Quote:
Originally Posted by buzzforb View Post
I was always unsure about using Peter's boards. Doesn't seem like there is good separation for heat dissipation. I will be interested to see if it feels like the heat is concentrated on your heat sinks with the middle being warmer than the ends. Looking forward to the results as I never went through with the project.
well its normally built with only 2 pairs, the third is there if you want, but the standard design only has 2 in use
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Old 29th October 2011, 12:54 PM   #28
6L6 is offline 6L6  United States
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That's how I am going to use it - 2 IRF240's for the Aleph current sources and 2 R100's for the output.
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Old 29th October 2011, 01:14 PM   #29
qusp is offline qusp  Australia
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yeah thats what i figured, so there should be no issue with uneven heat dissipation. i have a set of boards stuffed bar the fets with very similar parts: silmics, mills, a couple of zfoils for good luck, prp, caddock but with cornell dubilier smd RF teflon 4.7pf caps in the input filter in place of the ceramic caps.

so i'm watching your build with great interest as i had planned to try and do this myself, but was a little unsure of how to handle the R100 bias. you are building single ended mono blocks though aren't you? i'm trying for x'd so could be a bit more touchy, but setup should be roughly the same. i really do need a scope though i'm realising.
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Old 29th October 2011, 02:48 PM   #30
6L6 is offline 6L6  United States
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qusp -

I'm actually building a stereo amp in the image of the original Aleph.

As for biasing the R100, (I think, and anybody, please correct me if I am wrong) the bias is controlled by the resistor (now shown as a vey badly drawn potentiometer in my schematic) that connects V- to the gates of the R100. The 240's needed about 4v, the R100's about 1.2v .

So hopefully the substitution of that pot is all I need. Perhaps ZenMod or Nelson could chime in and shed a little light on it?
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