Dumb question about "matched transistors"

[MichaelW]

I've heard people mention from time to time about needing "matched quad set" of transistors for certain builds.

I just ordered the XC Phase board and it calls for 4x 2N5952's, do these "need" to be matched for this build?
What happens if they aren't matched?

Also, what spec am I matching?

TIA!!

 

[fig]

Vgs-off. The closer they are, the better it sounds...IMO.

Oh, and never a dumb question.

 

[Harry Klippton]

Every question is a dumb question

 

[MichaelW]

Ok follow up dumb question Alex, Ok to sub 5457's or J201's in this build? I have SMD's in both and more likely to be able to match.

 

[Deperduci]

you can, just know that they pinout is reversed, IE if you had the through holes the curve on the transistior would face the flat of the silk screen, think it was in the build notes of both MBP's and aionfx's phasers for substitutions...

 

[fig]

Every question is a dumb question

Really?

 

[Harry Klippton]

Really?

Some more so than others

 

[BryGuy]

So

Vgs-off. The closer they are, the better it sounds...IMO.

Oh, and never a dumb question.

So how do you measure Vgs-off? Seen some stuff about needing to build a circuit but can't remember where.

 

[BryGuy]

Well found this but still need to digest it.

http://geofex.com/Article_Folders/fetmatch/fetmatch.htm

Is there anything else one should know about matching jfets? Assuming there isn't an easier way to do it?

 

[Robert]

The easiest way would be to buy a matched quad set, but who wants to do that?

The next easiest way would be to use a DCA75... No jig needed, just connect to the transistor, hit TEST, and view the Vgs(off) voltage on the screen.

Either way (jig or DCA75) you'll basically just test a handful (or more) and hope to find a set with similar readings.

 

[fig]

I have a few sets laying about leftover from a couple of contests. Shoot me a message if needed.

 

[MichaelW]

I have a few sets laying about leftover from a couple of contests. Shoot me a message if needed.

Santa Fig at it again

 

[Feral Feline]

If you're subbing out the 5952 trans, I'd go with the 5457s rather than the J201s.

Not because I know what I'm talking about and have any experience, just simply because I've seen 5457s in phaser threads and advertised by vendors in matched sets... can't recall matched sets of J201s offered by anybody, though I may have seen a J201 in somebody's phaser build.

 

[Coda]

If you're subbing out the 5952 trans, I'd go with the 5457s rather than the J201s.

Not because I know what I'm talking about and have any experience, just simply because I've seen 5457s in phaser threads and advertised by vendors in matched sets... can't recall matched sets of J201s offered by anybody, though I may have seen a J201 in somebody's phaser build.

I think I got a matched set of J201’s from Aion for my PH-1r (Aion Emerald), SMD…

 

[Robert]

I've used J201 in a phaser prototype (unmatched, at that). They worked.

I can't comment on how they compared to 5952 or other transistors, so I'm not recommending you use them (matched or otherwise), but they did "work" ...

 

[jimilee]

In my experience with phasers, they have a higher output, so you will probably need to change your calibration trimmer pot to a higher value if there is one. Of course, I was working on an obscure phasor, and nothing else was working.

 

[Deperduci]

I knew from building a mxr 90 clone from mbp I ONLY decided to build after finding a matched set from different place for 5457s. They supposedly work with the same kind of trans, but sound like crap until they get closer tosimilar readings. I'm curious how many sets Mike will find with how many he acquired(I book marked that seller btwj being general acceptance fora set or w to come from tesing around 20-30....

 

[jimilee]

I knew from building a mxr 90 clone from mbp I ONLY decided to build after finding a matched set from different place for 5457s. They supposedly work with the same kind of trans, but sound like crap until they get closer tosimilar readings. I'm curious how many sets Mike will find with how many he acquired(I book marked that seller btwj being general acceptance fora set or w to come from tesing around 20-30....

Barry at Guitarpcb.com will put them on sale frequently for as low as .79 each. You can quickly stock up and measure them yourself. Just get in the mailing list,

 

[Deperduci]

Barry at Guitarpcb.com will put them on sale frequently for as low as .79 each. You can quickly stock up and measure them yourself. Just get in the mailing list,

it was when he last matched them I got mine.

 

[MichaelW]

I have a couple JFet Matcher boards from RullyWow. I've built one of them so far but it doesn't seem to work. Everything I've stuck in there measures 4.35v. So unless my WHOLE stash of JFETS are actually extremely closely matched and I could retire selling them as matched sets or my borked the build somehow. I'm going to try building it again with some of the spares I got.