fets for aleph P1.7

potepuh · 17th August 2006, 12:06 PM

I am colecting parts for my new project Aleph P1.7. I was wondering hoew many fets to i need to buy to get enough matche mosftets for a stereo version(4*IRF610 and 2*IRf9610 for mono) do i need to match also the ZTX 450/550?

Regards

Mad_K · 17th August 2006, 12:51 PM

I don't think you have to match anything

folkeb · 17th August 2006, 06:23 PM

From what I've heard you don't need to match the ZTXs, but you need to match the IRF610s and the IRF9610 as pairs. You should be able to buy pairs here on the forum

Makes it a lot easier...

Good luck!

Mad_K · 17th August 2006, 07:19 PM

Why would they need matching?

potepuh · 18th August 2006, 01:40 PM

Now I am a bit confused. Why not matched? Can I realy use unmatched fets?

Babowana · 18th August 2006, 01:53 PM

Quote:

Originally posted by potepuh

Now I am a bit confused. Why not matched?

A1.7 has output coupling caps, i.e. the output nodes see only AC.
So . . . we do not need to worry about the DC offset voltages at the outputs.
No one would blaim your matching MOSFETs.
No one would warn you about your unmatching MOSFETs, either.
Either way you could go unpon your free choice.

flg · 19th August 2006, 07:22 PM

Let me try to convey 2 cents. Someone can certainly straiten me out, if I'm confused. The diffamp/balanced topology needs a + and - side doing exactly the same thing to perform at it's best. The current sources will not provide the same current without the source R's and Vth and bipolars Vbe and even Beta being exactly the same. The bias level of the gain transistors, I beleive, is set in an area of the curve, that would also complement each other's opposite action with signal present. Not operating with the same current, side for side, will also effect their gain and balanced behaviour. Yes the DC output is protected by caps for the load but the more ideal both sides are, the better the performance!

wim · 19th August 2006, 07:43 PM

Much bigger broblem is to get the 10uF caps! I spent a lot of time on internet (google). In do not know were to buy them, conforming the BOM, with a leadspeace of 27,5 mm.

A groupbuy mayby??

folkeb · 19th August 2006, 07:46 PM

I had no problem fitting BG N caps into the pcb holes.

wim · 19th August 2006, 07:53 PM

Thanks for your quick answer mr. folkeb.

I know to use the alternative BG-N caps, bit suppose you want to fit the 1 uF caps, were to buy them (for a good price).

17th August 2006, 12:06 PM	#1
potepuh diyAudio Member Join Date: Feb 2004 Location: SLOVENIA	fets for aleph P1.7 I am colecting parts for my new project Aleph P1.7. I was wondering hoew many fets to i need to buy to get enough matche mosftets for a stereo version(4IRF610 and 2IRf9610 for mono) do i need to match also the ZTX 450/550? Regards

17th August 2006, 12:51 PM	#2
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	I don't think you have to match anything __________________ Mads K

17th August 2006, 07:19 PM	#4
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	Why would they need matching? __________________ Mads K

19th August 2006, 07:43 PM	#8
wim diyAudio Member Join Date: Sep 2003 Location: Nootdorp, Netherlands	Much bigger broblem is to get the 10uF caps! I spent a lot of time on internet (google). In do not know were to buy them, conforming the BOM, with a leadspeace of 27,5 mm. A groupbuy mayby?? __________________ Als er "X" artikelen benodigd zijn, blijken er "X" - 1 in voorraad te zijn.

19th August 2006, 07:53 PM	#10
wim diyAudio Member Join Date: Sep 2003 Location: Nootdorp, Netherlands	Thanks for your quick answer mr. folkeb. I know to use the alternative BG-N caps, bit suppose you want to fit the 1 uF caps, were to buy them (for a good price). __________________ Als er "X" artikelen benodigd zijn, blijken er "X" - 1 in voorraad te zijn.


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17th August 2006, 06:23 PM	#3
folkeb diyAudio Member Join Date: Jan 2006 Location: Trondheim	From what I've heard you don't need to match the ZTXs, but you need to match the IRF610s and the IRF9610 as pairs. You should be able to buy pairs here on the forum Makes it a lot easier... Good luck!

18th August 2006, 01:40 PM	#5
potepuh diyAudio Member Join Date: Feb 2004 Location: SLOVENIA	Now I am a bit confused. Why not matched? Can I realy use unmatched fets?

19th August 2006, 07:22 PM	#7
flg diyAudio Member Join Date: Jul 2005 Location: North East	Let me try to convey 2 cents. Someone can certainly straiten me out, if I'm confused. The diffamp/balanced topology needs a + and - side doing exactly the same thing to perform at it's best. The current sources will not provide the same current without the source R's and Vth and bipolars Vbe and even Beta being exactly the same. The bias level of the gain transistors, I beleive, is set in an area of the curve, that would also complement each other's opposite action with signal present. Not operating with the same current, side for side, will also effect their gain and balanced behaviour. Yes the DC output is protected by caps for the load but the more ideal both sides are, the better the performance!

19th August 2006, 07:46 PM	#9
folkeb diyAudio Member Join Date: Jan 2006 Location: Trondheim	I had no problem fitting BG N caps into the pcb holes.

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