Need help for Szekeres Class A Amp

Hey guys, bought this kit: http://www.ebay.com.au/itm/110722386484?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_8840wt_905 a while ago, based on the parts and schematics its based on Szekeres Class A amp design.

I've just got some questions for those who understand circuit diagrams and a little know how in electrical engineering, instead of any IRF513 or 613 power mosfet's being used, this kit is using the NEC 2SK3455 mosfet, I've got myself some protoboards to make this DIY a little easier and following the easier to read circuit diagram here http://williamneo.blogspot.com/2008/03/class-mosfet-headphone-amplifier.html the question goes if any know what the dgs (drain, source and gate) points for the NEC mosfet are/or direction.

Reading from page 7 on the datasheet here http://pdf1.alldatasheet.com/datasheet-pdf/view/112994/NEC/2SK3455.html, there's two diagrams, one says that pin's 1 2 and 3 are gate, drain and source, but on the diagram "equivalent circuit" next to the first one it shows that it is drain, gate and source? 

I'm a little confused to which pin is which and how I show go by completing the kit without burning the mosfet's.

Thanks

Quote:

Originally Posted by Avro_Arrow 

Use the gate/source/drain as listed in the ebay ad.

 

The 2sk3455 is a terrible mosfet to use for a Szekeres.

The input capacitance is 10x higher than the IRF510

that is usually used. The 2sk3455 will give you severely

rolled off highs.

 

The heat sinks for this kit seem incredibly small.

Thanks for that, what other IRF mosfet's would you recommend that will work with the rest of the ebay kit? In the orginal Szerkere's circuit diagram it uses 1N914 Diode's, 35v 1uf Metal capacitor and the IRF513 mosfet's.

In this ebay kit, the seller has provided IN4148 Diode's, 275v 1uf Metal capacitor and the NEC 2SK3455 Mosfet, would there still be rolled off highs with just 3 different components compared to Szerkeres original schematics?

I don't understand the way the seller on the ebay ad made his amp so I'm following this on a protoboard exactly:

So the question is, is it always D G S for the pinouts of any mosfet's? Because I was just confused from NEC's datasheet having one image say it is G D S and then the image next to it say's its actually D G S. If I mixed drain and gate when soldering would it toast the mosfets?

Yeah those are the heatsinks provided, but I got a bigger black one at home from a graphics card so I don't mind.

Thanks

Quote:

Originally Posted by Avro_Arrow 

MOSFET pinouts vary.

 

The IRF510 is kind of the default MOSFET for the Szekeres now

but there are others that will also work well. IRF630 also comes

to mind...

 

The diodes are there for signal overload protection and in normal use

should not be audible.

 

The "equivalent circuit diagram" does not imply the order of g/s/d.

The pin out in the data sheet is "as seen from above".

When looking at the MOSFET, with the writing facing you, pin 1

is to the left.

Both the ebay ad and the data sheet agree:

1. Gate

2. Drain

3. Source

 

IRF510 also shares this pin out.

 

Good luck with your build!

AH, thanks a million for that I thought so it was G D S/pin 1,2,3 from the datasheet, are the IRN510/630's compatible with this circuit? I don't like the slightly rolled off signature of that of the IRF series which I have in another amp currently.

Thanks

Sorry yeah I meant IRL510/610.

Sounds good to me, I know the the entire IRL range are better then the IRF range because of a simple change I did having IRL630's replace the stock IRF630 in my AU7 tube amp gave huge improvements, so it's good to hear that a simple mosfet can be changed for a different sound signature without affecting the enter circuit, like tube rolling and swapping op-amps.

Do you have any recommendations for transformers to use for Szerkeres amp?

Thanks

Ah yeah, I saw the 3 channel one through headwize's changelog for szerekeres amp, you got any pics of your amp?

EDIT: Just got back, going to start soon on soldering the Mosfet's still little bit confused, can I just solder the exact same as http://cdn.head-fi.org/4/40/4000505f_MosfetHeadphone.jpeg for my NEC mosfets? The D G S points same as the one in the diagram connecting to the different sections? What happens if I mix up on the D G S points soldered to different places?

Ok so I've got everything part of the circuit board done, now I just have to solder and attach the heatsink's, dc power connector, audio pot, headphone jack and 2 rca connectors.

Here's a picture of what is done so far following that circuit diagram and original schematics:

Green wire is ground in case your wondering.

Another question, for the dc connector and headphone jack....

The power connector which one is ground, positive and negative?

And when soldering ground, left channel and right channel, which part of the 6 pins do I solder it onto the headphone jack?

Does the ground on the middle bottom have to be touching the case? Because I'm using a green ethernet wire as my ground at the moment interweaving through the holes on the pcb, do I have to cut off the insulation of the wire in the middle bottom having contact with earth (i.e aluminium case etc)?