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Pass Zen V8 (Jfet) [message #10369] Sat, 21 January 2006 11:37 Go to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
In the group build thread below, Manualblock mentions the JFET
article by Nelson Pass in Audio Express. This article is also
available on the passdiy.com site. I have an order in on the
group buy for the Lowvoltec JFETs. Look at
diyAudio Forums > Top >Market Place >Group Buys
for this. Evidently the minimum quantity on these is huge, hence
the group buy. I've ordered more than I need, I will have a few
extra, should you need them.

I hope to build several variants on this and would be happy to
work with anyone here who is doing likewise. We can each make
half the mistakes that way.

Skip Pack

Re: Pass Zen V8 (Jfet) [message #10370 is a reply to message #10369] Sat, 21 January 2006 15:39 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
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Registered: May 2009
Illuminati (13th Degree)
Say Skip Pack; is that amp the J3 that is listed on Nelson's site?

Re: Pass Zen V8 (Jfet) [message #10371 is a reply to message #10370] Sat, 21 January 2006 17:00 Go to previous messageGo to next message
Skip is currently offline  Skip
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Chancellor
Hello,

The amp I'm talking about is at the following
URL.

http://www.passdiy.com/pdf/ZV8_power_jfet.pdf

He is also selling the Firstwatt F3, which
I understand is a much fancier implementation.
This ZV8 (the one in the Audioexpress article) is
so much like a tube amp that it would be easy to
explore lots of configurations that I can understand
because I have been paying more attention to tube
basics.

Skip

Re: Pass Zen V8 (Jfet) [message #10372 is a reply to message #10371] Sat, 21 January 2006 17:39 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Yes I understand the particular piece you mean; I thought maybe he was marketing one of his own. As a tube guy what do you think of the chip amps?

Re: Pass Zen V8 (Jfet) [message #10373 is a reply to message #10372] Sat, 21 January 2006 20:56 Go to previous messageGo to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
I don't have a tube power amp, though I do have a
Foreplay II which I have enjoyed for a good while.
I was going to start putting together tube amps when
the gainclone thing started. I heard the 47 Labs
Gaincard(s) at Yoshi Segoshi's home around 2002 and was
impressed. Once I became aware of the gainclones
emergence, I built some, and have been consistently
impressed.

At the Lonestar Bottlehead's meeting a week ago, I
listened to my gainclone followed by Wardsweb's Sex
amp. I thought the sex amp was the better amp up to
volumes louder that I ever listen at. It wasn't
radically better, but clearly better. I tend to
think that well done tube amps are usually better
than SS, but that SS is catching up. As you know,
you could easily put together a good gainclone for
$150, including an attractive chassis/box. Mine
is a standard version 1.0, single transformer from
Brian Bell. I think I can put together a much better
gainclone with Carlos Felipe's snubberized supply
and seperate powersupplies.

I suspect that the Jfet amps could be very good. Hope
to see/hear if that's true.

Skip

Re: Pass Zen V8 (Jfet) [message #10374 is a reply to message #10373] Sun, 22 January 2006 07:39 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Yes; I heard the 47 labs at a meeting of the audio society here and they used a pair of Audio Physics loudspeakers that ran about 6K$. It sounded good.
Your point about the price is well taken not to mention the hassle of tubes. I have always wanted equipment with the ease of use of SS but there has never been the quality and musicality you get with tubes. Even Nelson will admitt that.
That being said; the GC is definately listenable and this new concept,( actually New/old concept), sounds really good.
Can you say a little more about the group build you mentioned?
It looks so simple it is hard to believe it can work.

Re: Pass Zen V8 (Jfet) [message #10375 is a reply to message #10374] Sun, 22 January 2006 09:32 Go to previous messageGo to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
I assume that you are referring to the ZV8 as far as building.
I wasn't aiming at a formal group build, but more toward
communicating while building with others doing the same
thing. I'm not anywhere knowlegeable enough to do anything more
than put together the design as shown, and then, maybe,
embroider around the edges. The group buy is underway with
plenty of the JFETs available:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=71633&perpage=10&pagenumber=1

The rest of the items are very much off the shelf, junkbox
to boutique. The only difficult thing would appear to be
heatsinking the less common package of the JFET.

Discussion of the JFET amp

http://www.diyaudio.com/forums/showthread.php?s=&threadid=64292

This thing intrigues me because it looks like you could easily
choke load it (if you could find the high-current choke), or
use two modules in push-pull. Maybe even feed two modules with
a center-tap-primary transformer just like a PP tube amp. It
all seems approachable if you're willing to stand way back
when you power it up in the middle of your back yard.

Skip

Re: Pass Zen V8 (Jfet) [message #10379 is a reply to message #10375] Mon, 23 January 2006 19:09 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
BTW just read your post on recording recomendations in the other forum and thanks; we don't get much in the way of music recommendations here so when someone offers something new it's greatly appreciated.
On the DIY forum I find the thread discussing the JFET amp but no offering of a joint buy for parts. I know I am missing something in your earlier post regarding that.
Just follow that link exactly as written and there should be info there is that right?
The JFET is a nice idea because I like the Class A amps almost as much as tubes and they are a lot less high maintenence; are you going ahead with the project if I may ask?

Re: Pass Zen V8 (Jfet) [message #10380 is a reply to message #10379] Mon, 23 January 2006 20:22 Go to previous messageGo to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
Maybe my last post contained a confused reference. You can get to the
group buy by going to www.diyaudio.com, then to 'Market Place' then
to 'Group Buys'. Finally, look at the thread titled 'Lovoltech LU1014D
power JFET'. That has all the information. The fellow doing the work,
Grey Rollins, has a huge number of JFETS on hand and is welcoming more
orders. I think I will do the project, how fast, I don't know. My first
step are experiments on a power supply with some surplus finds (I don't
know if they are actually finds yet). I think I will breadboard the
whole thing first. I've never done that before, and it sure offers
some advantages.

Re: Pass Zen V8 (Jfet) [message #10381 is a reply to message #10380] Tue, 24 January 2006 06:00 Go to previous messageGo to previous message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Excellent; thanks. Did you build the GC; I think you mentioned that?

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