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Ultimate 4U 500mm Chassis - Who is interested?
Ultimate 4U 500mm Chassis - Who is interested?
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View Poll Results: Base Plate Option
Standard Aluminium 3mm or 4mm 5 23.81%
Aluminium + Custom Perforated Steel Base Plate 470mm to 480mm 16 76.19%
Voters: 21. You may not vote on this poll

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Old 28th February 2021, 03:17 PM   #1151
Zen Mod is offline Zen Mod  Serbia
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Ultimate 4U 500mm Chassis - Who is interested?
making TIG welder?

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Old 28th February 2021, 03:33 PM   #1152
HeyBill is offline HeyBill  United States
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Ultimate 4U 500mm Chassis - Who is interested?
Amp plus TIG. Great idea. Listen while you work.
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Old 28th February 2021, 04:35 PM   #1153
AlexRivera is offline AlexRivera  United States
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For some reason I thought we could fit two 8 pairs PCBs per side so 16 pairs total but now I realize the maximum is 12 pairs per side
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Old 28th February 2021, 04:39 PM   #1154
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Ultimate 4U 500mm Chassis - Who is interested?
Ozorfis - Thanks! Look for a PM. I think I have the switch sorted, but I don't think I've ever been so paranoid. Plus, I don't really want to order "mini-PCBs" for the DIP switch, so...

ZM - A guy's gotta do, what a guy's gotta do. No purpose other than to learn, and b/c I can. I admit it hurt a bit to take apart the other amp, but...

HeyBill -

I gotta admit, just looking at them makes me smile. That's enough for now to keep me going.

Edited to add - AlexRivera - you can put 24 with no extra tapping ... depending on the layout of the PCB.
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Last edited by ItsAllInMyHead; 28th February 2021 at 04:41 PM.
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Old 28th February 2021, 04:59 PM   #1155
AlexRivera is offline AlexRivera  United States
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Quote:
Originally Posted by ItsAllInMyHead View Post
AlexRivera - you can put 24 with no extra tapping ... depending on the layout of the PCB.

You are right, itís just a matter of using an aluminum bar across the transistors to fix the ones without a screw, that may work for Class A/B, for pure Class A 12 pairs may me more that what the heathsink can dissipate, isnít it?
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Old 28th February 2021, 05:15 PM   #1156
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Ultimate 4U 500mm Chassis - Who is interested?
Quote:
Originally Posted by AlexRivera View Post
You are right, it’s just a matter of using an aluminum bar across the transistors to fix the ones without a screw, that may work for Class A/B, for pure Class A 12 pairs may me more that what the heathsink can dissipate, isn’t it?
Sorry for poor description. I was talking about just in theory vs. amps I know of that can take advantage of it.

If someone designed an amp with a set of PCBs that had 12 devices on the "upper" side of the board and 12 on the "lower" side of the board, they'd fit in like a treat with the UMS. There's 12 "unused holes" in mine. Think F5 Turbo layout with MOSFETs up and down. Otherwise, I've seen creative builders have their PCBs perpendicular to the heatsinks and "back to back" for BA builds. Itsmee should get credit for passing that idea along to me when I was going to do this in a 5U/400. Now that I have this chassis, there is no need.

Your second piece is the "real" piece that probably matters most. Heat. It would depend on the amp, the devices used, and the bias. A BA-3 with 24 devices, even with my "low" 24V rails and biased to 0A75 per device would still be 432W to dissipate. I biased my "6 device" BA-3 to 1A0 per device in the 5U/400 just to test it out, and thermals were okay. So, I feel pretty good that getting to 0A5 with 12 per side with these sinks should be fine.

Someone should check my math though... not my strongest suit.
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Last edited by ItsAllInMyHead; 28th February 2021 at 05:24 PM.
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Old 28th February 2021, 05:16 PM   #1157
ozorfis is offline ozorfis  Germany
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Just in case you change your mind. Attached is the solution of somebody else, that I found on this forum. I will do something similiar with my toshiba versions. I resoldered the gnd connection a couple of times already and one time I might end up burning my caps like 6L6 did.

Good luck and best of wishes
Ozo

Quote:
Originally Posted by ItsAllInMyHead View Post
Ozorfis - Thanks! Look for a PM. I think I have the switch sorted, but I don't think I've ever been so paranoid. Plus, I don't really want to order "mini-PCBs" for the DIP switch, so...

ZM - A guy's gotta do, what a guy's gotta do. No purpose other than to learn, and b/c I can. I admit it hurt a bit to take apart the other amp, but...

HeyBill -

I gotta admit, just looking at them makes me smile. That's enough for now to keep me going.

Edited to add - AlexRivera - you can put 24 with no extra tapping ... depending on the layout of the PCB.
Attached Images
File Type: jpg ba3fe.jpg (522.9 KB, 189 views)
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Old 28th February 2021, 05:42 PM   #1158
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Ultimate 4U 500mm Chassis - Who is interested?
That's exactly what I was looking at. See PM. Don't want to get this group too OT.

Thanks!
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Old 2nd March 2021, 03:58 AM   #1159
Mrdrewk is offline Mrdrewk  United States
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Default XLR RCA or both?

Is it a bad idea to wire up both rca and xlr connectors?

Is an XLR with rca adapter on it way worse? I was thinking of doing some future proofing here.
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Old 2nd March 2021, 06:41 AM   #1160
ozorfis is offline ozorfis  Germany
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I soldered both XLR and RCA inputs together with shielded cables and had no ill effect. Soon I will try with unshielded cables.

Noise Figures:

- inputs open : around 0,35 mV
- inputs shorted: around 0,15 mV
- RCA open and XLR cable connected to DAC: 0,15 mV

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