I am going to try the IRFD9610 in place of the JFETS to see how that turns out.
Neither octopart.com nor digikey.com list a component called IRFD9610.
Here are all of the components on the DigiKey website, whose part-numbers begin with IRFD: (list).
Perhaps you meant IRFD9010 or maybe IRFD9110 ... ?
Yes Mark, I know.
That's how I build 99% of my projects (including Pearl I with 2sk369).
Question was if anyone else had contemplated a similar idea and potential pitfalls.
Leaving "D" out of the part number, you can find pretty good bargains on octopart.com
For example, this distributor quotes a price of $17.63 for 50 parts. You'll probably get way more than two matched pairs from a bag of 50 units. I've never ordered from these folks so I have no data about their shipping speed or customer service.
For example, this distributor quotes a price of $17.63 for 50 parts. You'll probably get way more than two matched pairs from a bag of 50 units. I've never ordered from these folks so I have no data about their shipping speed or customer service.
Member Gaz2613 thinks that enhancement mode MOSFETs will work in that circuit as replacements for 2SJ74s, and he may very well be right. He proposes to use IRF9610s, which are enhancement mode Pchannel MOSFETs in the TO-220 package.
A pragmatist experimenter might decide, "while I wait and wait and wait for inexpensive 2SJ74s to arrive, I might as well try an enhancement mode MOSFET replacement. If it works, I've got music much sooner. And if it doesn't work, I'm no worse off than when I started."
I've been using the Microchip TP2104 and TN2106 in recent projects. For those considering enhancement mode MOSFET replacements for 2SJ74 JFETs (depletion mode), these might be possibilities.
They're made by Microchip, who has a much stronger than average commitment to thru hole packaging for semiconductors. (Probably because they still sell zillions of PIC microcontrollers in DIP packages). Thousands of these MOSFETs are on the shelf at many different distributors, making them easy to buy internationally as well as within the US. Price is less than USD 0.75 in qty=1. Package is TO-92. Pinout is SGD, which is a simple 180 degree rotation from the Toshiba 2SJ74 (DGS).
here is the datasheet
They're made by Microchip, who has a much stronger than average commitment to thru hole packaging for semiconductors. (Probably because they still sell zillions of PIC microcontrollers in DIP packages). Thousands of these MOSFETs are on the shelf at many different distributors, making them easy to buy internationally as well as within the US. Price is less than USD 0.75 in qty=1. Package is TO-92. Pinout is SGD, which is a simple 180 degree rotation from the Toshiba 2SJ74 (DGS).
here is the datasheet
The front end of ACP+ is practically the same as the front end of an Aleph amp.
Aleph 2/3/4/5/30/60 employed IRF9610, Aleph J used 2SJ109 which is like two SJ74 in a single package.
So enhancement mode IRF9610 (or ZVP3310) and also depletion mode SJ109.
Taking into account the cost of 2 pairs of SJ74 from the store here to my place down under (US$60- / AU$95- ) and the cost of locally sourced either IRF9610, or FQP3P20, or ZVP3310, I know which ones I would prefer to use.
I don't know if there will be some sound quality penalty.
I'm willing to experiment and find out.
Aleph 2/3/4/5/30/60 employed IRF9610, Aleph J used 2SJ109 which is like two SJ74 in a single package.
So enhancement mode IRF9610 (or ZVP3310) and also depletion mode SJ109.
Taking into account the cost of 2 pairs of SJ74 from the store here to my place down under (US$60- / AU$95- ) and the cost of locally sourced either IRF9610, or FQP3P20, or ZVP3310, I know which ones I would prefer to use.
I don't know if there will be some sound quality penalty.
I'm willing to experiment and find out.
to Stanislav #293
Hello Stanislav,
I was thinking something similar like you.
Replacing the two 2SJ74 in the ACP+ with ZETEX ZVP3310.
The ZVP 3310 has a gfs of ca. 50mS and Ciss of ca. 50pF.
Adjusting the CCS (J113) above .... I would run the ZVP3310 at 4-5mA
or perhaps higher.
But you would have to buy a lot of ZVP3310 and match 2 pairs.
Also cost/time - intensive!
My experience is, that the ZVP/ZVN3310 (also from one batch) have a wide spread in their values.
I have built a preamp with ZVN3310 and ZVP3310 running on 32V rails.
(Recipe from Mr. Pass - FIRST WATT - 1998 - DIY Op Amps)
Sounds pretty good. In my opinion a bit 'darker' in the highs.
Could be worth a try to test ZVP3310 in the ACP+?
But you know - that is another recipe - different from that what the 'master-cook' was presenting to us.
In my opinion the active devices in the first stage have a very big influence
on the sound character.
Greets
Dirk
Hello Stanislav,
I was thinking something similar like you.
Replacing the two 2SJ74 in the ACP+ with ZETEX ZVP3310.
The ZVP 3310 has a gfs of ca. 50mS and Ciss of ca. 50pF.
Adjusting the CCS (J113) above .... I would run the ZVP3310 at 4-5mA
or perhaps higher.
But you would have to buy a lot of ZVP3310 and match 2 pairs.
Also cost/time - intensive!
My experience is, that the ZVP/ZVN3310 (also from one batch) have a wide spread in their values.
I have built a preamp with ZVN3310 and ZVP3310 running on 32V rails.
(Recipe from Mr. Pass - FIRST WATT - 1998 - DIY Op Amps)
Sounds pretty good. In my opinion a bit 'darker' in the highs.
Could be worth a try to test ZVP3310 in the ACP+?
But you know - that is another recipe - different from that what the 'master-cook' was presenting to us.
In my opinion the active devices in the first stage have a very big influence
on the sound character.
Greets
Dirk
Hello Stanislav,
I was thinking something similar like you.
Greets
Dirk
Hello Dirk,
Great to read about your experience with ZVP3310. I find it very encouraging.
The thing is I almost never follow recipes to the full, always tweaking with what I've on hand, what I find affordable, and still of good quality.
Like:
MOT instead of Hammond 193
2sk369 instead of 2sk170
12AH7 instead of 6SN7
IRFP150 instead of 240
IRFP9140 instead of 9240
and so on.
I find this much more rewarding than following the recipe to the letter.
Yes, slightly different flavour, but how do you tell which one is better?
Or is there such a thing as better?
As they say beauty is in the eye of the beer holder.
Back to the topic - I think ZVP3310 is a great candidate for an Aleph front end.
Another option is TP2104 as Mark Johnson suggested, even cheaper here from RS.
Matching is a non-issue, plenty of time, dedicated workshop just for electronic matters. Also plenty of devices on hand, don't even have to buy them (but will buy some TP2104 just to try them).
Another thing is I like headphone amps, but only simple ones.
I have ZenLite (@ 48V /0.6 A), E88CC SRPP, ACA (@20V / 1.5A).
So I think ACP+ can be another one and a prelude to a J2 clone with FETs.
Prost
Stan
Recently spoke with Nelson Pass and he said he doesn't object to making of PCBs as described here...
Mark
Mark
Hi Mr. Pass,
JPS64 has also developed a nice layout of the ACP+ to be compatible with the M2X front end module bolt pattern. We will provide the Gerber files here, and also offer the PCBs to the community for cost of manufacturing and shipping/handling. The boards will use some large SMT parts on the underside to keep things compact. Through hole parts on top. Please let us know if you are good with this.
Thank you.
xrk971 & JPS64
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Hi Variac,
Thank you for letting us know that Mr Pass doesn't object.
Thanks,
X
As promised, here are the Gerbers (with pdf schematics and stuffing guides), and BOM in .XLS format so that you can order your own PCB's.
If folks are interested in getting the PCBs, I will put them up in my shop which handles the logistics of getting the boards out efficiently.
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