F5 power amplifier

[labjr]

You don't need to match the outputs if you're using a single pair.

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[Rixsta]

Thanks what about the other Fets?

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[labjr]

The JFET inputs need to be matched.

 

[Rixsta]

Can I match transistors with RS ? Otherwise I better buy my Transistors from Diyaudio store unless anyone can recommend a member I get them from.
Also do I need low ids ?

Cheers

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[Sangram]

I think it was Patrick that found that matched Idss Jfets do not have matched transfer curves.

And Nelson mentioned somewhere that the Pch Jfet should have Idss 80% of Nch, for close transfer curve.

In any case, given that the output devices will have different Vgs causing the input devices operating at different points anyway, and the presence of P3, input devices should be from the same Idss bin but not necessarily matched. I build with matched parts as well as unmatched, and cannot reliably identify any difference.

RS/Darnell do not offer matched devices or matching services.

 

[ColinA]

I think a lot build with mosfet output devices just "off the shelf." I did with no problem. (from Digikey)

Jfets, it is most important to make sure that they are genuine.
Purchase from store, or Spencer on here to be sure. Not E-bay from China.

I have seen "little diode" in the UK mentioned but no one states their quality.

 

[Rixsta]

Thanks for the info people ill stay away from China for sure even though sometimes good prices.
I guess I'm safe with diyaudio shipped to UK nice and easy.

I plan to make a really nice sounding amp to beat my Jean Hiraga 20w with smps.

Will be powering this amp with SMPS..

Thanks for the help.

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[Bksabath]

Spencer
Yes !

 

[Rixsta]

Can someone send me to his page because it seems hard to do on this Tapatalk

Also what grade Ids would be good for F5

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[Rixsta]

Think I found him. Looks like he's from China

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[ColinA]

Spencer
diyAudio - View Profile: spencer

You must E-mail him for prices.
skcheung68@hotmail.com

 

[Dennis Hui]

C
Also what grade Ids would be good for F5

Per Papa's post here, ask for 8+ mA Idss:

http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-64.html#post1504253

Dennis

 

[AudioSan]

Spencer do have a webshop.
Shop FET Audio | Hi-End Audio Projects

 

[Rixsta]

Looks like Spencer does have in that ma but how about this ?
Should be fine ?

http://diyaudiostore.com/collections/parts/products/linear-systems-matched-jfet-pairs-grade-b



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[gadut]

Spencer already increased jfet price, i think that it will be around $19/pair. I have bought from alweit for my previous build, which is $14/pair, hopefully he will not increase it too. I paid same price in this month for 4pairs.

diyAudio - View Profile: alweit

 

[AndrewT]

Makes the LSK170 B grade matched pair that I sold seem like peanuts in comparison to those vastly inflated prices.

I still have lots of LSK170 A and C grade matched pairs. Properly matched pairs !

 

[2 picoDumbs]

Makes the LSK170 B grade matched pair that I sold seem like peanuts in comparison to those vastly inflated prices.

I still have lots of LSK170 A and C grade matched pairs. Properly matched pairs !

Do you have lsk170 with idss around 15mA

 

[AndrewT]

Yes, I have 1pr @15.4mA, 1pr @ 15.6mA and 1pr @ 15.9mA

Prices in swap meet.
But you are not in the UK.
Foreign postage is a big hassle since I don't live near a post office.

 

[jeanie21]

With a tight budget I never hesitate buying components from China using eBay. There are a number of well established vendors with a track record.

 

[ColinA]

With a tight budget I never hesitate buying components from China using eBay. There are a number of well established vendors with a track record.

Might be of more use to people if you named names.
Blanket "some are ok" does not help purchasers.