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Old 1st April 2012, 02:11 PM   #1931
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Above 10W or so there can't be too much difference as it's starting to get "loud".

Undoubtedly above 25W the Class AB, Class B and above come into their own.

Where the Class A is in its own league is at normal listening levels, unless you have no friends.

I started with a 30W Class A amp and the Aleph 4 at 100W Class A is definitely superior. Wether or not this was down to different designs we will never know. The 30 Watter did run out of steam at high volume.

If you chase the threads there is a strong contigent that just love the JLH and Hiraga 10W Class A designs.

The BEST Class A/B designs use Class A at the crossover point, what they do with the remainder of the power curve is what makes them unique.

Last edited by KatieandDad; 1st April 2012 at 02:17 PM.
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Old 1st April 2012, 04:12 PM   #1932
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Quote:
Originally Posted by limono View Post
keeping the layout as is how big is the risk of oscilations
BIG.

It's not just the inductance of the wiring going back and forth, but also the proximity of the MOSFETs to the big heatsinks.
(aka Apoo made a real poo-poo of the GM, as bad as it gets)
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Old 1st April 2012, 04:29 PM   #1933
limono is offline limono  United States
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Quote:
Originally Posted by jacco vermeulen View Post
BIG.

It's not just the inductance of the wiring going back and forth, but also the proximity of the MOSFETs to the big heatsinks.
(aka Apoo made a real poo-poo of the GM, as bad as it gets)
OK, than what do you suggest? If I use L alu bracket on the back and position transistors to align with the holes on PCB and attach bracket to the back of chassis will there it be enough heat sinking in this arrangement? Regards, L
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Old 1st April 2012, 10:08 PM   #1934
Liliya is offline Liliya  Norway
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Limono

If your heatsink is long enough to house GM board, this is the way I would done it. If you look at the original GM, the heatsink they use, is not that big.

Use the second heatsink from your cabinet to another prosject

Eivind Stillingen
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Old 1st April 2012, 11:00 PM   #1935
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Quote:
Originally Posted by limono View Post
If I use L alu bracket on the back and position transistors to align with the holes on PCB and attach bracket to the back of chassis will there it be enough heat sinking in this arrangement ?
Nope.

How many inches are left between the board and the front panel ?
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Old 2nd April 2012, 01:15 PM   #1936
limono is offline limono  United States
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Well, There are only 6" (14cm) behind the board to fit transformer. In this chassis there is no other choice than
A) cluster transistors close together on both side of the heatsinks and hook it up with wire.
B) attach small L brackets to both sides of heatsinks with 3 transistors each and run the wires to the board.
There is no space inside to position the board any other way and fit transformer
except maybe positioning the board side way with transistors facing heatsink and using two small 200V-250 transformers on each monoblock or scraping the chassis and building a different one.
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Old 2nd April 2012, 02:56 PM   #1937
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What i would do :

- rotate the board in the amp case, output stage facing the transformer.
- saw the output stage part of the board.
- Tilt it at a 90 degree angle off the main board.
- mount it on an L-angle (0.2" minimum thickness), other flange facing up.
- attach the L-angle to an aluminum square bar that fits like a glove inbetween the heatsinks (1.5" x 1.5" or preferably 2" x 2")
- attach the square bar to the heatsinks on both sides (threaded holes and allen bolts, or with a small bracket on opposite sides of the bar, plenty thermal paste)

Connections between both boards with drilled holes and wire links.

Refurbishing cost of $50-$75 tops. You could cover up the holes in the heatsinks with an alloy strip.
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Old 2nd April 2012, 03:22 PM   #1938
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hmmm, rotating the pcb is a good idea but you might not need to saw the pcb, just attach the L angle to the board attach the L angle to a square bar and attach square bar to heatsinks.

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Old 2nd April 2012, 03:27 PM   #1939
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Goldmund works perfectly and the sound is best I've heard.
I currently Aleph2, Aleph5, F5, F5balanced, AEM6500.
Goldmund 9.2 for me is the top.
Very fast, very balanced and superb dynamics with very good bass.
I do not get enough of it
We used all components after original scheme.
Goldmund is very stable.
I 3mV output;
bias - 90mA per transistor;
AC - 60V (+82 V,-80V);
DC - 70 V.
The picture signal to 1kHz,10kHz,100kHz.
Now working on the case, I'll come back with more results.

I want to thank very much to Nikos, Alex mm and Liliya for help and advice.
Thank you!
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Last edited by vitalica; 2nd April 2012 at 03:41 PM.
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Old 2nd April 2012, 03:33 PM   #1940
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Quote:
Originally Posted by apoopoo999 View Post
hmmm
Wrong (again) !
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