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-   -   2sk1058 mosfet amp (http://www.diyaudio.com/forums/solid-state/170502-2sk1058-mosfet-amp.html)

tubem 20th July 2010 03:17 AM

2sk1058 mosfet amp
 
Hi this is my first thread, I have just completed a very nice version of Mark Houston 2sk1058 mosfet amplifier. It sounds excellent and looks real nice too. I hope to have pictures of it posted on the solid state projects page soon, that would be nice.:rolleyes:

doctortube 21st July 2010 02:22 AM

Welcome to the forum .I am looking forward to viewing the images of your project .

doctortube 21st July 2010 02:59 AM

Pic.
 
2 Attachment(s)
Thanks for the pics . Could you show the inside .

larryldspkr 25th July 2010 02:10 PM

sweet sounding amp!
 
I listened to this amp for about 9 hours, it sounded very nice...good dynamics...smooth...way bigger than its 5 watts!! It drove my Tannoy's with room to spare. I want one!!

tubem 27th July 2010 12:38 AM

inside pic
 
1 Attachment(s)
inside pic as per your request.

wabun 27th July 2010 01:01 AM

can share the schematic ah ?

taj 27th July 2010 01:26 AM

What a curious amp. Can we see the schematic?

..Todd

tubem 27th July 2010 01:31 AM

It's Mark Houston's
 
1 Attachment(s)
It's Mark Houston's
Class-A 2SK1058 MOSFET Amplifier

doctortube 27th July 2010 03:39 AM

Nice amp tubem ! The choke looks as big as the tranny Nice point to point wiring .What are you going to build next ?

ilimzn 27th July 2010 01:21 PM

It has the classical error of misunderstanding maximum output swing.
In the positive direction, this would be (Vdd-Vq)Rl/(Rd+Rl)
In the negative direction, this is a bit more complex and depends on how far you want to go into saturation with the MOSFET, but it will be about Vq-2V,
where Vq is the quiscent voltage on the MOSFET drain (adjusted by the pot, this also changes idle current), Vdd is the power supply, i.e. 24V, Rd is the 15 ohm drain resistor and Rl is the load. Assuming an 8 ohm load, you get about 4.17V in the positive direction, and about 9-10V in the negative direction, which results in very asymertical clipping and quite serious reduction in maximum output power before clipping - only about 1W into 8 ohms.
Although it is possible to calculate maximum swing, it involves a compromise regarding distortion, so your best bet would be to measure with a scope, adjusting for symetrical clipping on a triangle waveform, while observing the linearity of the triangle. Themn listen, and fine-tune as needed.
In general, you will have to adjust a larger idle current, and Vq will be less than half Vdd, about 7-8V!
Keep in mind that this adjustment is heavily dependant on the intended load, so this is another thing that must be optimized for.
You ight also want to relocate the power resistors to the main heatsink. As it is, the amount of heat generated on them is exactly tehs ame as that on the MOSFET, so it is not logical to give them a smaller heatsink. In the output-swing optimized condition, the restsors develop more heat then the MOSFET, so the more logical it is to put them on the larger sink.


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