To Toshiba or to Fairchild?

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dewdrop

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Joined 2004
I did try to search the forum for answers but couldn't find one.

I am building the F5T amp, and collecting the parts.

2 questions, should I invest in:
1. the NOS Toshiba 2SK170-BL/2SJ74-BL or the LINEAR SYSTEMS MATCHED LSJ74/LSK170 JFET PAIRS (GRADE B)?

2. The Toshiba 2SJ201-Y / 2SK1530-Y Grade A N/P Matched Octa or just go for the Fairchilds IRFP240/IRFP9240?

TIA!
 
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ColinA123

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Joined 2017
I.M.H.O.
If you can buy from a reputable source, (like Spencer.)
Then use Toshiba.
If you are unsure of the source or the grade, for simplicity use LS from the store.

With such a low part count and most of the money in the transformer and case
it seems silly to me to scrimp on Jfet quality.
 
EUVL

EUVL

Member
Joined 2003
xen-audio.com
> If you are building quite a few amps using mosfets, then buy both back have a direct comparison .....

We did, Nelson did, as did quite a few others for sure ......

http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1516.html#post4786961
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-147.html#post1567486
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1519.html#post4793601

http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html#post1993284
http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html#post1994725


Patrick
 
H

Hikari1

Member
Joined 2012
I've had all 3 mosfets in my f5...but it wasn't really a fair comparison since the toshibas were dual pairs bs single pairs for the Fairchild and IRF.

For most people IRFs are the only choice considering the availability of the toshiba and Fairchild parts is so low.

I do remember the difference between Fairchild and IRF was not as large as I expected...
 
EUVL

EUVL

Member
Joined 2003
xen-audio.com
> For most people IRFs are the only choice

As long as they are still available, and they are, I do not see the logic of saving money on one of the most important components that determines SQ.
Especially when considering the money one has to spend on Tx, Caps, cases ' heat sinks, connectors, .... for a Class A power amp.


Patrick
 
mpmarino

mpmarino

Member
Joined 2004
EUVL said:
As long as they are still available, and they are, I do not see the logic of saving money on one of the most important components that determines SQ.
Especially when considering the money one has to spend on Tx, Caps, cases ' heat sinks, connectors, .... for a Class A power amp.


Patrick
Click to expand...

I don't doubt that the Toshiba devices sound better. It's probably the way to go.....

But at that point it isn't the F5 in the proper sense. Technically the commercial F5 was built with the Fairchild Q-fets, correct? In the states, for a newcomer sourcing the Toshibas is a daunting task, not to mention the Fairchild devices becoming more and more scarce.

I'm only saying this, as it would be a shame if the amp were not built because people were intimidated by device availability. I haven't built the F5 yet so I'm just blabbing, but can we say that the Toshiba devices are the ultimate upgrade path for the F5, and don't let the lack of availability or cost of ownership hold things up?

Rochester still has a ton of the Fairchilds at a decent cost, but you have to buy a TON.

I heard that there is a mad scientist on the West coast that is holding the world's supply of these thingies. His plan is working MUHAHAHAHAAAAA :)
 
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