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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
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Old 13th June 2019, 02:11 AM   #11
jwjarch is offline jwjarch  United States
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Asuslover, yes, these are NOT passive heatsinks. They need a constant flow of air. A 92x92mm computer case fan would fit well. Noctua and Arctic have silent fan models and an additional resistor can be added to slow the fan down and make it even quieter. Just be careful not to add too much resistance and stall the fan out.
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Old 13th June 2019, 02:17 AM   #12
carlthess40 is offline carlthess40  United States
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What’s the price and where in the USA do we buy all the parts or is this GB come complete with all parts but the case and rca’s and stuff. Just what’s needed for the broads
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Old 13th June 2019, 05:02 AM   #13
xrk971 is offline xrk971  United States
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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
Depending on level of interest, the pricing will be circa $60/pair, as boards will be 2mm thick, 2oz copper, and ENIG finish. Projects from Aksa/JPS64/jhofland/xrk971 are typically just well documented and tested/verified PCBs with a detailed BOM. Oftentimes, Vunce or Zman01 will be kind enough to work up a completed Mouser/Digikey/Arrow shopping cart so ordering parts is easy. It's not a "kit", as you have to do some homework. However, the ABBB is a complete amp minus the chassis, CPU coolers, and power transformer. All you need to do is hook up the trafo, the speakers, the RCA input, and chassis ground. You also need to mount the power transistors onto suitable heatsinks or CPU coolers. Look in the original Alpha 20/BB thread to get ideas on active cooling with CPU coolers and PWM fans. It is a compact, low-cost way to remove up to 160w per active safely and easily. One other important point is that the ABBB amp section is adjustment free. The cap Mx portion has an adjustment pot to set the level of voltage dropout (and hence level of ripple control vs voltage dropout). We recommend about a 3v drop and for most purposes, that might be something we can set in stone with a fixed resistor vs using a trimmer pot to make the ABBB truly "adjustment free". I bring this up because many Class A amps have 2, sometimes 3 trimmers that have to be adjusted simulatneously and over a long period to allow thermal equilibrium, and there is a procedure. No such thing with the Alpha amps.
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Last edited by xrk971; 13th June 2019 at 05:08 AM.
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Old 13th June 2019, 11:04 AM   #14
gary s is offline gary s  Australia
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Thanks for the update X, any move to get rid of trimmer pots and make it all adjustment free is good. Even the best multi turn trimmer pots are not the most reliable of components in the long term.
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Old 13th June 2019, 02:17 PM   #15
xrk971 is offline xrk971  United States
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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
I totally agree with eliminating all trimmers on ABBB - Aksa, Jhofland, JPS64, Vunce, and myself will discuss merits - also, option to put in a second set of pads for a fixed resistor vs a trimmer.
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Old 13th June 2019, 02:46 PM   #16
shattered_dream is offline shattered_dream  Germany
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gary s - 2 boards
jwjarch - 2 boards
Vunce - 2 boards
meanie - 2 boards
shattered_dream - 2 boards
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Old 13th June 2019, 03:05 PM   #17
marc brown is offline marc brown  United States
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What size chassis do you recommend for a stereo build? Chassis to contain 2 boards and trafos.
thanks!
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Old 13th June 2019, 03:25 PM   #18
yoaudio is offline yoaudio  United States
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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
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gary s - 2 boards
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Old 13th June 2019, 04:13 PM   #19
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by jwjarch View Post
Thanks for the info Hugh. That's a pretty slick DC protect system. Very hi-tech! Well done you guys!

Good to know there’s no unobtanium parts once again.

I have 8 of these guys to put to use. I've posted this info on the Alpha thread before, but if anyone needs a cheap cooler here you go. They were made to dissipate at least 130W on Xeon servers and have large copper pads on the bottom. Should be able to handle one mosfet per cooler I would think. Need 4 for an ABBB. I used these to test out my Alpha 20 build and they worked really well.

HP ProLiant CPU Heatsink DL580 DL980 G7 LGA1567 570259-001 591207-001 | eBay
Can you provide some rough dimensions of the copper pad on the bottom of these? Also, can that be drilled? I assume only a blind hole would work and a thru hole would compromise the heat pipes?

If they cannot be drilled, how to you secure the device to the sink?
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Old 13th June 2019, 04:19 PM   #20
xrk971 is offline xrk971  United States
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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB
Quote:
Originally Posted by marc brown View Post
What size chassis do you recommend for a stereo build? Chassis to contain 2 boards and trafos.
thanks!
As the board contains the bridge rectifier, CRC, Cap Mx, amp proper, SSR protection circuit, it saves a lot of real estate. All you need room for is the trafo. Assuming you are using a 500VA toroid from Antek AN-5428, they are about 6in dia and 3in high. I don't have exact size of the amp board, but about 7in to 8in wide x about 5in deep. Add 1 in clearance on all sides, so 10in wide x 14in deep x 6in high per channel. This does not include the CPU heatsinks, which will sit on top in the open and depending on model are 6in wide x 4in deep x 6in to 8in tall ea. You could put them front to back like Vunce did here to give you an idea (this was for Alpha 20):
Click the image to open in full size.

So, for stereo, make twice as wide or 22in wide x 14in deep x 6in high. This is too wide and I think you may want to play with placing PCB above trafo or mounting trafo standing on edge. Personally, I think two monoblocks is a better way to go size wise and it won't be so heavy.

AN-5428 - 500VA 28V Transformer - AnTek Products Corp
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