Which Pass Amp to build F5/F6/Or anything else?

[Dennis Hui]

Consider getting these:

Toshiba 2SJ74 LAB MATCHED QUAD to 0.03mA / 4mV ("B" "BL" 7-9mA Range) | eBay

 

[hanair]

Great coincidence! I was just going through the offers from that seller!

He also has a pack of 20 for the same price but not matched. My thinking was if I could find matching ones myself, I could use the remaining for other projects.

 

[bergy]

improved Aleph J

In no particular order, BA-3, Aleph J, M2x.

You cannot go wrong with any of the Pass designs in general.

it would be a dream have the possibility to build an amplifier, that sounded like an Aleph J, adding it the woofer control and dynamic bass capacity of an old KRELL KSA... would become a legend

 

[Dennis Hui]

hanair,

I looked at Punkydawgs' other listings and I found one for 20 pcs of 2sj74GR (for $50)
and another for 20 pcs of 2sj74BL (for $75). For the Aleph J, the standard
recommendation is to use BL parts.

The Idss range of the BL parts is between 6mA and 12mA. So with 20 of them
you are guaranteed to get a couple pairs each matched within say 0.4mA. This is
better than the recommended 1mA tolerance mentioned here:

JFET matching information – diyAudio Store

 

[hanair]

Unless of course the seller is selling left over from the matching process in these bundles.

 

[Dennis Hui]

It doesn't matter. If you have 20 parts with Idss in that range then you can always find pairs meeting these limits. There's no guarantee the pairs are close to each other but they are there.

 

[nr12]

I ordered 20 of those
QTY 20 - 2sj74bl Toshiba J-FET "B"/"Bl" Klasse-Authentic-Brand Neu (6-12ma) | eBay


two weeks ago. Should be here in two weeks (still stuck in california...)
I will measure them and report my findings.

 

[hanair]

Where do you source the signal transformer for M2x?

 

[zman01]

hanair,

The transformer is made by Edcor.

 

[airborne11b]

Where do you source the signal transformer for M2x?

Edcoreusa.com

 

[hanair]

Thanks zman01! I found it!
EDCOR - PC600/15K

(built to order; 10-12 weeks!)

 

[Nelson Pass]

If you are paralleling the Mosfets they must be matched, generally for Vgs within .1V

Other applications, the matching is not so important, although is does cater to
the audiophile craving for perfect symmetry.

 

[Zen Mod]

That's why I invented Feet mounted on both amp lids/covers

besides flipping it for phase reasons, now I can choose should I heat or fridge my room



next stage of invention is random rotation of amp Fascia, for amusing increase of user's confusion

 

[zman01]

next stage of invention is random rotation of amp Fascia, for amusing increase of user's confusion

Hmm... ZM now entering digital era, wants to change "themes" of the device like teenagers do with their phones?

Or still old-school - just change the cover?

 

[Zen Mod]

naah

it's as (intentionally confusing) addendum to major part of Invention - you never know how amp is oriented, what phase is, and is it heating or cooling your room

 

[zman01]

ZM is always teenager - teenager with amps!

Amps are much better looking than phones anyways... (and bigger too)

 

[Zen Mod]

though about implementing Lazy Susan in Invention, still not being able to solve cables issue

 

[woody]

Hanair, with a lot of us ordering those transformers it might very well take that long wait time. But I and several others here have ordered them when the wait time was posted as probably 8 weeks and been pleasantly surprised when we got them in about 2 weeks.

 

[zman01]

And if you are feeling impatient, the F6 parts kit with transformers is available at the diyAudio Store.

 

[hanair]

Already ordered 2SJ74BL!