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Old 20th April 2009, 08:52 PM   #11
CfM is offline CfM  Germany
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Quote:
Originally posted by cviller
I'll pick up suggestions from you guys before diyAudio puts it into production.
Hi Christian,

nice layout, a few first suggestions after quick look:
- Q203 should be heatsinked, so a bit space around it would be great. I would suggest putting it a little bit down, away from Q202 and the resistors right to it a bit to the right.
- C204 could also use some more space, e.g Wima FKP2 or Vishay KP1830 both have 4.5 mm width.
- C203 is very long but slim. Did you have any special capacitor in mind? Only 2 or 3 mm wider and a MKP10 would fit (20 mm)

Thanks to Nelson for sharing!

Greetings,
Chris
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Old 20th April 2009, 09:30 PM   #12
Variac is offline Variac  United States
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I may be guilty of contributing this idea: The thought was that the cap could hang over the edge and be secured by a wire-tie around the outside of the board and through the hole in the board next to the cap.. This would pull the cap to the outside so maybe the MKP would fit? ....Comments?

I think that these would fit..

26x37mm Jantzen Z-Standard cap $7.16

http://www.parts-express.com/pe/psho...=027-282&DID=7

Ultra premium caps are usually pretty fat, This one is
long and skinny, so fits well.. (and expensive) $44.15
36x107 Jantzen Z-superior
http://www.parts-express.com/pe/psho...=027-497&DID=7
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Old 20th April 2009, 09:35 PM   #13
valo is offline valo  Norway
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Hi

What is the output power of this amp?
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Old 20th April 2009, 09:41 PM   #14
PSz. is offline PSz.  United States
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It starts clipping into 8 ohms at about 25 watts.
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Old 20th April 2009, 10:33 PM   #15
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Is that 25 watts for the four or six output transistor configuration?

25 watts per channel seems low if the amps are dissipating 300 watts per stereo channel and the output stage is drawing 3.5A at 50V. Where are the missing 100 watts?

- Eric
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Old 20th April 2009, 11:42 PM   #16
PSz. is offline PSz.  United States
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Quote:
Originally posted by Eric Weitzman
Is that 25 watts for the four or six output transistor configuration?

Both. It is a voltage limitation.
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Old 21st April 2009, 12:35 AM   #17
Variac is offline Variac  United States
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psz,

Are your outputs all 240 devices- single ended?
So you may build this?

Mark
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Old 21st April 2009, 12:53 AM   #18
PSz. is offline PSz.  United States
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Nope, I've got the big complementary mosfet version. As you already noted, that can be easily changed.

best regards,
psz.
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Old 21st April 2009, 07:37 PM   #19
Variac is offline Variac  United States
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Quote:
25 watts per channel seems low if the amps are dissipating 300 watts per stereo channel
Nelsons article says

Quote:
The power transformer should be rated at 600 VA or more. Two channels of this amp will typically draw in excess of 300 watts, and we allow at least a 2 to 1 transformer margin.
So I think this means that each channel draws 150 watts for 300 total for 2 channels, then you apply the 2 to 1 transformer margin and get 600VA rating for the transformer. The transformer is for both channels

Mark
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Old 21st April 2009, 09:05 PM   #20
CfM is offline CfM  Germany
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Quote:
Originally posted by Variac
I may be guilty of contributing this idea: The thought was that the cap could hang over the edge and be secured by a wire-tie around the outside of the board and through the hole in the board next to the cap.. This would pull the cap to the outside so maybe the MKP would fit? ....Comments?
The idea is ok as long as the boards with capacitor still fit into the cabinets (cviller: "The board is 3" x 3.5", and one of the primary design constraints is that it must be able to fit into the cabinets"). I would expect that if the board with overlapping capacitors fit, it would also be possible to enlarge the board.

As the board is layouted now only axial caps would fit, if the board area is fixed maybe Christian can move the pads a few mm more to the edge so that radial caps would also fit (also hanging over the edge).

Chris
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