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50w Single-Ended BAF2015 Schade Enabled
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Old 6th September 2019, 01:03 AM   #811
vdi_nenna is offline vdi_nenna  United States
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50w Single-Ended BAF2015 Schade Enabled
Default Getting Around to It

Finally made some progress. Put together to see how it all fits. Panels still have plastic coating.
Case is always the toughest part.
Built this one with just a cordless drill.
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Old 6th September 2019, 01:15 AM   #812
dantwomey is offline dantwomey  Canada
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No time right now to read your post but here is my first attempt at part of the input PCB.

Regards,
Dan
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Old 6th September 2019, 01:50 PM   #813
dantwomey is offline dantwomey  Canada
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How much current flows through R9 and R6?

Regards,
Dan
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Old 6th September 2019, 03:50 PM   #814
Zen Mod is offline Zen Mod  Serbia
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50w Single-Ended BAF2015 Schade Enabled
max swing/(R9+R6)=Ipp

say 60Vpp ( just to have round figure)

60Vpp/(220+22)R= 248mA

P=I^2 x R , but you need to translate Ipp to Irms , so to speak (recalculate AC to DC ,effectively) so Ipp/2/1.41 = 87mA

dissipation in resistors:
for 220R= 87mA^2 x 220R=1W69

for 22R = 0W169

so , 220R - use 3Watter

for 22R - use whateverWatter
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Old 7th September 2019, 05:36 AM   #815
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Quote:
Originally Posted by vdi_nenna View Post
Finally made some progress. Put together to see how it all fits. Panels still have plastic coating.
Case is always the toughest part.
Built this one with just a cordless drill.
That amplifier looks like serious business! I like the aluminum plate used for the panels.

You may have talked about this earlier, but are you going to use the heat sinks passively or with fans? I seem to recall dissipation is ~180W a side, a lot for even the biggest passive heat sinks.
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Old 7th September 2019, 09:32 AM   #816
vdi_nenna is offline vdi_nenna  United States
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You may have talked about this earlier, but are you going to use the heat sinks passively or with fans? I seem to recall dissipation is ~180W a side, a lot for even the biggest passive heat sinks.
This is a smaller 25w version.
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Old 7th September 2019, 12:36 PM   #817
dantwomey is offline dantwomey  Canada
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Quote:
Originally Posted by Zen Mod View Post
max swing/(R9+R6)=Ipp

say 60Vpp ( just to have round figure)

60Vpp/(220+22)R= 248mA

P=I^2 x R , but you need to translate Ipp to Irms , so to speak (recalculate AC to DC ,effectively) so Ipp/2/1.41 = 87mA

dissipation in resistors:
for 220R= 87mA^2 x 220R=1W69

for 22R = 0W169

so , 220R - use 3Watter

for 22R - use whateverWatter
Trying to figure this out so I can determine what trace width I need on the PCBs Iím designing.

Regards,
Dan
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Old 10th September 2019, 12:37 AM   #818
vdi_nenna is offline vdi_nenna  United States
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In post #49, Pico mentioned a trim pot might be needed. What are we adjusting for?

Finished the amp today and brought it up slowly with a variac. Nothing blew up or smoked, but getting a few volts under rail voltage at the drain of the lower mosfet. Raising the bias 2 volts didn't change anything. No warm up on heat sink.

Rail - 41v
Volts at drain- ~38V
No change at drain adjusting bias
No change at drain adjusting trimmer above opti-coupler.
Results are same on both channels.

I have a lm317 voltage regulator for bias and grounded it at main circuit ground point. That ok?

Using fairchild irf9140 mosfets.

Ran out of time today but will mark a copy of the schematic with reading when I get a chance.

Thanks

Vince
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Old 10th September 2019, 07:33 AM   #819
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by vdi_nenna View Post
......

Ran out of time today but will mark a copy of the schematic with reading when I get a chance.
....
please
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Old 14th September 2019, 02:06 PM   #820
dantwomey is offline dantwomey  Canada
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Originally Posted by Ben Mah View Post
Not necessarily fixes of flaws, but merely some suggestions - I'm also just a diyer, definitely not educated in electronics but have done some reading, never designed a printed circuit board, but I have wired point to point circuits on boards:

1. Take J2 off the end of resistor R5 instead of off pin 4 of 4N37.

2. You can keep traces on the bottom of the board if you move the trace that is between the IXFN drain (3) and R1. From drain (3), run trace from the lower side of (3) horizontally between (1) and (2), and then turn up to R1 (on the bottom of the board).

3. For +60V power, enter board to the left of R2 and above drain (3), and go directly to (3).

4. It is my understanding that a ground return should be provided next to the power wire (twisted) to minimize loop area and therefore noise. So I suggest you bring your 60V and ground wires twisted together to the board. If all of the circuit traces are on the bottom of the board, you can then put a ground on the top side, entering next to the 60V, then down over the IXFN, and then horizontally across and exit near J2 and J3. You might need to enlarge the space for R4 and R5 anyways so then there is room to bring a wide ground trace across under the resistors to the right side of the board. You can then continue ground wires with the power and signal out wires at J2 and J3, again twisted together to minimize loop area.

This is a good read for minimizing noise. It is by diyAudio member Bonsai:

http://hifisonix.com/wordpress/wp-co...ound-Loops.pdf

It is a long read, but the practical information is towards the end. I have found it very helpful and I try to follow his recommendations. In all my amps I have ground and power wires twisted together, and signal ground wires twisted together, with the goal to minimizing loop areas. All my amplifiers are quiet with my 103 dB speakers.
How's this?

Regards,
Dan
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