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Old 4th July 2013, 12:52 PM   #811
naf is offline naf  Indonesia
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Shaan, please ada optional compesation cap. on vas incase somebody want to use ksa/ksc/sa/sc transistor.
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Old 4th July 2013, 12:55 PM   #812
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Quote:
Originally Posted by shaan View Post
This is my plan...

Dimension: 4.3" x 2"

Please comment.

Thanks.

shaan



edit: Underboard FET mount.
I like it very much. Nice and compact and I like the power connections together like you have done.

Any comment on the idea of bootstrapping the IPS and VAS to get a PeeCeeBee to swing closer to the rail? Simulation suggests getting about 5V closer to the rails. With 40V rails and no bootstrap clipping occurs at 68W (33Vp into 8 ohm) and with bootstrap clipping begins at 90W (38Vp into 8 ohm). Doesn't sound like much, but headroom is headroom and only takes a few passive components to get it.
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Old 4th July 2013, 02:29 PM   #813
PMI is offline PMI  United States
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Very nice, and clean layout!
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Old 4th July 2013, 02:37 PM   #814
shaan is offline shaan  India
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Quote:
Originally Posted by naf View Post
Shaan, please ada optional compesation cap. on vas incase somebody want to use ksa/ksc/sa/sc transistor.
Okay.

Quote:
Originally Posted by jkuetemann View Post
I like it very much. Nice and compact and I like the power connections together like you have done.
Thanks.

Quote:
Any comment on the idea of bootstrapping the IPS and VAS to get a PeeCeeBee to swing closer to the rail? Simulation suggests getting about 5V closer to the rails.
I haven't tried the bootstrap config you posted so can't make solid comments. However, there are two more diodes in each rail demanding their own switch-off noise to be atennuated - one more capacitor per rail. Also, being a positive feedback node the bootstrap is prone to invite oscilation, if not implemented correctly, meaning we need scopes.

That aside, it's great to see new possibilities explored.

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Old 4th July 2013, 02:55 PM   #815
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Shaan what is , other than price and availability, choosing 2 // latfet per rail than a double die as ALFET ALF16N16W with background off place saving and no matching needed?

Marc
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Old 4th July 2013, 03:28 PM   #816
shaan is offline shaan  India
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Shaan what is , other than price and availability, choosing 2 // latfet per rail than a double die as ALFET ALF16N16W with background off place saving and no matching needed?

Marc
Better dissipation, more space between FET leads, ease of drawing amateur layouts, peace of mind etc. You know, we average diy-ers often make bad thermal coupling and demand most from the least. Makes us different.
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Old 4th July 2013, 03:36 PM   #817
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Shaan what is , other than price and availability, choosing 2 // latfet per rail than a double die as ALFET ALF16N16W with background off place saving and no matching needed?

Marc
It seems that the Exicons are a slightly different package/pin spacing than the Renesas parts. I am planning to make a small revision of my circuit board, and I was hoping to accomodate that package, but there is another small issue. As far as I know, those parts do not have internal protection diodes, so those should probably be added to any layout.

I believe that those parts, just like the Alfets, are intended to be used with a faster pair of drivers (at least the Profusion web site seems to suggest that), so I think that would also mean compensation resistors, and carefully chosen gate resistor values. I have done some of that on my board already, but it seems not to be necessary if one is to follow Shaan's schematic and logic in chosing parts.

The boards I have build with close to the component selection published at the beginning of this thread seem to have identical sound to the second set, which uses "better" parts. (Even when I have taken the amp to a couple friends with better speakers).

I see some differences on the o-scope, but not much with my ears. I plan to compare to LC's modules as soon as I have a suitable "home" for them...

Exicons and Alfets do not seem to be easily available in the US from conventional distributors - If you or anyone else has an idea where to get them, plese post it or pm me, thanks...
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Old 4th July 2013, 04:03 PM   #818
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Yes PMI
- renesas => TO3P package
- ALF16N16 => TO264 package same as MJL bipo; bigger than To247

Marc
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Old 4th July 2013, 04:54 PM   #819
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...we average diy-ers often make bad thermal coupling and demand most from the least. Makes us different.
Hey! I may have made bad thermal coupling decisions in the past (well, I am pretty sure of it), but I am "in recovery" now. ...and btw, I am quite proud of my 12-dollar heatsinks. I'll be a bit sad when I finally have them anodized, it will spoil the industrial look...

I would also say that even though I have made a few changes to my test board set over the last few weeks, the version I listen to almost every day is pretty close to the original schematic published here, and with a smaller heatsink than the one shown below.

I plan to use the same heatsink, 0.65C/Watt with the VSSA modules from Lazy Cat. Although the chassis may look slightly different, the heatsink corner pieces allow it to be thermally coupled to the front and back, so the overall dissipation will be about what LC specified, despite the compact chassis and smaller/cheaper heatsinks.
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File Type: jpg VSSA_heatsink1.jpg (230.4 KB, 285 views)
File Type: jpg VSSA_heatsink2.jpg (233.2 KB, 246 views)
File Type: jpg VSSA_psu2.jpg (258.4 KB, 236 views)
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Old 4th July 2013, 05:07 PM   #820
PMI is offline PMI  United States
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Originally Posted by Idefixes View Post
Yes PMI
- renesas => TO3P package
- ALF16N16 => TO264 package same as MJL bipo; bigger than To247

Marc
Looks like the board would have to be extended about 5 mm on either side, even if everything else stays the same.
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File Type: jpg VSSA1Bassy6.jpg (214.6 KB, 228 views)
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