[Avro_Arrow]

What are you using for a power supply?
The hum could be due to not enough power supply filtering.
 
I agree that ethernet wire is a poor choice for wiring.
Even some stranded 18 gauge from Radio Shack would be better...
 
Compare the working side to the non-working side for any difference.
It is possible the MOSFET is blown on that side.

 

[DefQon]

Quote:

What are you using for a power supply?
The hum could be due to not enough power supply filtering.
 
I agree that ethernet wire is a poor choice for wiring.
Even some stranded 18 gauge from Radio Shack would be better...
 
Compare the working side to the non-working side for any difference.
It is possible the MOSFET is blown on that side.

I don't think the mosfet is blown up, a mate of mine who is a electrical engineer brought his multimeter and checked the contacts on the circuit I soldered together, the mosfet was reading 0.0v so it must've been a dud, anyway I've emailed the ebay seller yesterday and told him about my situation, kindly enough he is sending two more mosfets today via airmail which I should receive in a week or two.
 
As with the humming, now that you've mentioned that it could be insufficient power, I think this may be the case because it does say on the ebay ad and Szerkeres original project page that a regulated power transformer of 9-15v with 2amp's or more is required, 4amps being optimum. My current transformer is a 12v 0.8amps, or 800milliamps, so it is a bit underpowered.
 
Since now I know my amp works, I will be replacing the ethernet cable with a thick clear insulated 20 awg silver plated copper wire, I got a 30 meter spool and it was intended to be used for the home theater system, but heck I got plenty left so bit of it won't hurt on the amount I will have left.
 
Just another question, with the audio pot can I solder it with contacts leading from left/right out and any ground point? Since left/right out would be the sound output into a headphone/earphone.
 
Thanks
 

 

[Avro_Arrow]

Yes, you can use any ground point for now, but if you
rebuild this one or build a new one you want to try and
lay it out to have a "star ground". What this means is
that all of the ground connections come to one point.
If you can see it in the picture of my amp, the star ground
point is near the middle of the board.
 
Once you get the amp working properly, you can work on
getting rid of any hum from the power supply. 

 

[DefQon]

Ok, just started working on this again, oddly enough with the new mosfet's in, only one of the mosfet's get warm to hot, but the amp will only work if i bridge the two connections from each side on the headphone jack, if I don't bridge the left and right channel the amp doesn't work and the mosfet's won't heat up. Although with both mosfets replaced by the replacement while ago, both channels now work with the exception of the mildly loud humming noise in the background music probably due to the current ripple in the transformer which I need to replace with a 15V 2amp+ transformer.

 

[jsvilla93]

Hello, all i also bought the skeezer amp on ebay and looking to replace mosfet can anyone give me an idea as to which mosfets are the best sounding.
Joe

 

[Avro_Arrow]

IRF510 is commonly used in Szekeres.
 

 

[jsvilla93]

Quote:

IRF510 is commonly used in Szekeres.
 

Thanks for the info i currently have the IRF510 and IRF610 but i hear some say the highs are quite rolled off.Comparing to what mosfets i dont know? but ive ordered some IRL510 and IRL610 because ive read there better. Currently ive built the ebay version but changed resistors to dale and used IRF610 mosfets everything worked when powered up but my problems are the volume is low and it takes up to 16 volts or more to produce sound which isn't very good. Sounds distorted. Any ideas could it be the gate resistor? Thank you everyone for the help.
Joe

 

[Avro_Arrow]

If you add a JFET buffer in front of the MOSFET, you can get rid of the roll off all together.
 
Gate resistor values should be in the range of 100 to 220 ohms, but you can experiment
to find the best value. I run my Szekeres off a 20 volt power supply with 150mA of
bias.
 
The Szekeres is not really an amplifier, it has a gain less than one, typically .95 dB
 
The link above also links to the original Szekeres project so you can check that for
troubleshooting.

 

[DefQon]

I eventually changed my IRF630 to a IRL510. Sounds great slightly more treble without being rolled off. More sparkled ends.