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Old 26th October 2012, 01:29 AM   #481
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Sorry, I only built one channel. give me a day or three.

I'd like to bring up another potential problem, ground. Many of the laptop supplys I looked at had the power line safety ground connected to the minus side of the output. One naked OEM 24V PCB supply didn't have that ground and the supply for my Toshiba only has a two wire line cord. What type supply is shipping with the kits?
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Old 26th October 2012, 02:57 AM   #482
winslow is offline winslow  United States
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I know nothing about designing amps, but could you parallel a pair rather than bridge them?
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Old 26th October 2012, 11:47 AM   #483
Zen Mod is offline Zen Mod  Serbia
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yes , you can

paralleling - when you need Ampers

bridging - when you need Volts
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Old 26th October 2012, 01:11 PM   #484
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Quote:
Originally Posted by Zen Mod View Post
yes , you can

paralleling - when you need Ampers

bridging - when you need Volts

Zen Mod and winslow. You have a Eureka. Parallel 2 ACAs [the kits c/o Variac] and bridge them with another pair of ACAs. This way you'll overcome the limitations we spoke of earlier:
  • Have 2 A idle per pair.
  • Have adequate power supplies
  • Have enough heat sink
  • No need to modify the original circuits.
  • Get 20 W output power into 8 Ohm. A parallel pair of ACAs will still give 5 W into 8 Ohms by comparison.
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Old 26th October 2012, 06:20 PM   #485
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Quote:
Originally Posted by Antoinel View Post
Zen Mod and winslow. You have a Eureka. Parallel 2 ACAs [the kits c/o Variac] and bridge them with another pair of ACAs. This way you'll overcome the limitations we spoke of earlier:
  • Have 2 A idle per pair.
  • Have adequate power supplies
  • Have enough heat sink
  • No need to modify the original circuits.
  • Get 20 W output power into 8 Ohm. A parallel pair of ACAs will still give 5 W into 8 Ohms by comparison.


winslow: Most probably you'll ask; how does one pair up two ACAs? The attached file [bridgeACA3.pdf] shows a proposed diagram which [I hope] Pass, Zen Mod, Loudthud, and janneman [plus others] will frisk it and give us their blessing [with modifications where needed] for its feasibilty.
  • I show an ACA#1 upper, and an ACA#2 upper.
  • I am using the numbering protocol of the components used in the published schematic of ACA by Mr. Pass.
  • The identical diagram applies for the partner pair in the bridge configuration [ not shown]. Same discussion applies fully.
  • I show the passive approach to generate the out of phase input signals with the JENSEN transformer.
  • An allowance for the approach by janneman is shown in ACA#1; at the drain of the front end FET [2SK170].
  • The output of the upper ACAs are joined at their existing output [in kit].
  • ACA#1 is completely assembled as recommended in the article by Mr. Pass.
  • ACA#2 is partially assembled. Leave out R11, C3, R12, R10, VR1, the front end FET [2SK170] and R9.
  • Connect a shielded signal line from the source of 2SK170 [junction R9 and R6] of ACA#1 to R6 in ACA#2. Hopefully, Q1 [output MOSFET] in both ACAs are matched to some extent so as to not disturb centering each ACAs output to ~10 VDC with VR1.
  • Repeat the above for the partner pair of the bridge.
Attached Files
File Type: pdf bridgeACA3.pdf (41.0 KB, 118 views)
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Old 26th October 2012, 06:48 PM   #486
billyk is offline billyk  United States
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Not to sidetrack this...

I finished my pair Monday and they have been playing since then. They sound very nice, lots of detail and very musical to my poor old ears. Hooked up to some NHT Super Ones on one side and PassDIY B-1 on the other, playing through my PC's digital out to a CAL Sigma DAC.
Thanks to Nelson ans Variac and everyone else that made these little wonders so easily attainable!!
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Old 26th October 2012, 07:45 PM   #487
kikko is offline kikko  Italy
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My ACA kit arrived yesterday!
I needed to celebrate the event... so i created the last fashion in diy themed T-shirt...
That t-shirt can keep you warm while soldering or be used as reminder to the ACA circuit schematics....

Thank you diyaudio!
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Old 26th October 2012, 08:05 PM   #488
tinitus is offline tinitus  Europe
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now that is real dedication
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Old 26th October 2012, 08:52 PM   #489
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Quote:
Originally Posted by kikko View Post
I needed to celebrate the event... so i created the last fashion in diy themed T-shirt...That t-shirt can keep you warm while soldering or be used as reminder to the ACA circuit schematics....
I want one!!!! That should be in the apparel section of the DIYAudio store!! I'd like to order one in xlarge please
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Old 26th October 2012, 10:36 PM   #490
Variac is offline Variac  United States
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Hmmm I think that might be a good idea..
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