# Dumb question about "matched transistors"



## MichaelW (Sep 3, 2022)

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!!


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## fig (Sep 3, 2022)

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

Oh, and never a dumb question.


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## Harry Klippton (Sep 3, 2022)

_Every_ question is a dumb question 😉


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## MichaelW (Sep 3, 2022)

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.


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## Deperduci (Sep 3, 2022)

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...


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## fig (Sep 3, 2022)

Harry Klippton said:


> _Every_ question is a dumb question 😉


Really?


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## Harry Klippton (Sep 3, 2022)

fig said:


> Really?


Some more so than others


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## BryGuy (Sep 3, 2022)

So


fig said:


> 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.


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## BryGuy (Sep 3, 2022)

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?


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## Robert (Sep 3, 2022)

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.


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## fig (Sep 3, 2022)

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


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## MichaelW (Sep 3, 2022)

fig said:


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


Santa Fig at it again


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## Feral Feline (Sep 3, 2022)

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.


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## Coda (Sep 3, 2022)

Feral Feline said:


> 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…


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## Robert (Sep 3, 2022)

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" ...


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## jimilee (Sep 3, 2022)

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.


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## Deperduci (Sep 3, 2022)

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....


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## jimilee (Sep 3, 2022)

Deperduci said:


> 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,


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## Deperduci (Sep 4, 2022)

jimilee said:


> 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.


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## MichaelW (Sep 4, 2022)

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.


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## Deperduci (Sep 4, 2022)

have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?


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## Kroars (Sep 4, 2022)

MichaelW said:


> 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?
> ...


Just in case:









						2N5952 Quad Set for Phasers - GuitarPCB
					

N-channel Jfet 2N5952 Quad Set - Hand Matched - Genuine Fairchild Tested.




					guitarpcb.com
				




They are out of stock now, but he often updates his stock.   I believe I have two sets coming to me, should be delivered in a week or less.  I only need one set now, so if you want to send me a message I’d happily send you a set if you need for the cost I bought them for.  

Happy building!


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## MichaelW (Sep 4, 2022)

Kroars said:


> Just in case:
> 
> 
> 
> ...


Yah, there's a couple places that is selling matched sets, most are out of stock. I'm pretty well loaded up on MMBF5457's, I think I'll try to get my JFet Matcher working right and find a matched set out of my inventory.


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## MichaelW (Sep 4, 2022)

Deperduci said:


> have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?


I think I've tried them. The board clearly makes DSG spots and I matched those. I haven't spent too much time trying to troubleshoot. But I guess now's as good a time as any I had to order 3 boards from Oshpark. I'm going to try to build out another one.


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## BryGuy (Sep 4, 2022)

I might try these from Aion since I don’t have much of a stash of jfets to sort currently.









						2SK208-GR JFET (matched set of 4)
					

This is a matched set of 4 2SK208-GR JFETs for use in phasers such as the BOSS PH-1r, pre-soldered to adapter boards for through-hole applications.




					aionfx.com


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## spi (Sep 4, 2022)

I use the ROG technique to measure my jfets.



			A closer look at the Fetzer Valve


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## Coda (Sep 4, 2022)

spi said:


> I use the ROG technique to measure my jfets.
> 
> 
> 
> A closer look at the Fetzer Valve



Yep. Works good.


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## fig (Sep 5, 2022)

MichaelW said:


> 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.





spi said:


> I use the ROG technique to measure my jfets.
> 
> 
> 
> A closer look at the Fetzer Valve


I believe that’s what the jFET Matcher Michael has is based on, though there are a few versions (improved, greatly improved, cheetah-supreme). It’s not too deep of math and was fun to work out _once_, but the online calc is killer. I now use a Peak thingy and it does everything but solder the little bugger for me.


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## jimilee (Sep 5, 2022)

Tagboard has some great jfet matcher circuits.


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## Chuck D. Bones (Sep 5, 2022)

It's not enough that they are matched.  Vgs,off needs to be in the correct range for the phaser to work.  2N5457 has a HUGE Vgs,off range and the ones at the high end won't work.  The Vgs,off range for 2N5952 is -1.3V to -3.5V.  If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.


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## fig (Sep 5, 2022)

Chuck D. Bones said:


> It's not enough that they are matched.  Vgs,off needs to be in the correct range for the phaser to work.  2N5457 has a HUGE Vgs,off range and the ones at the high end won't work.  The Vgs,off range for 2N5952 is -1.3V to -3.5V.  If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.


Remember those 2N5248s? I still have all of those matched quads. I never did try any in the Phase 90, but I will now!


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## Chuck D. Bones (Sep 5, 2022)

I think you mean 2N5246.  Good option.  Pick ones with the higher Vgs,off.


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## fig (Sep 5, 2022)

Chuck D. Bones said:


> I think you mean 2N5246.  Good option.  Pick ones with the higher Vgs,off.


I came back to correct myself and here you've taken care of me. Will do 😘


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## MichaelW (Sep 15, 2022)

Chuck D. Bones said:


> It's not enough that they are matched.  Vgs,off needs to be in the correct range for the phaser to work.  2N5457 has a HUGE Vgs,off range and the ones at the high end won't work.  The Vgs,off range for 2N5952 is -1.3V to -3.5V.  If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.


Hey @Chuck D. Bones, I've managed to come up with 4 matched MMBF5457's but they're a bit higher than your suggested range.
-1.19, -1.19, -1.19, -1.34

Think these will work in a Phase 90?

I've got a crap ton more MMBF547's but they're not mounted on adapters. Got a suggestion on how to test those little suckers?
I can't get my micro clips to stay on the legs. 

I suppose to could mount a dozen of them and see if I get any better ones....


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## MichaelW (Sep 15, 2022)

Ok, I made a little jig to test SMD JFETs...

I pulled 10 MMBF5457's and unfortunately none of them were close. VGs off measured in the -.5-.7 range on all 10.

I wonder if its because they were MMBF5457*LT1*'s. I'm not completely sure what the LT1 designation denotes.


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## MichaelW (Sep 15, 2022)

Broke down and bought a matched quad from Barry, he had them on sale. 

I'm planning to socket and test them against my matched set of 5457's as well as some random J201's.


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## swyse (Sep 15, 2022)

MichaelW said:


> Broke down and bought a matched quad from Barry, he had them on sale.
> 
> I'm planning to socket and test them against my matched set of 5457's as well as some random J201's.


I'm interested to see the results of your experimenting, I'd like to build a phaser at some point but am not excited about matching jfets.


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## MichaelW (Sep 15, 2022)

swyse said:


> I'm interested to see the results of your experimenting, I'd like to build a phaser at some point but am not excited about matching jfets.


I'll update this thread when I get to building. But you can build the Phase II and skip all this crap 😄


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## MichaelW (Sep 15, 2022)

Deperduci said:


> have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?


Incidentally, I'm an idiot, I did have them in the wrong way . There was nothing wrong with the first matcher I built.


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## Deperduci (Sep 15, 2022)

MichaelW said:


> Incidentally, I'm an idiot, I did have them in the wrong way . There was nothing wrong with the first matcher I built.


cool, I'm going try to build that on perfboard, got a small stack of mounted 5457's I hope I can find a pair for to make a 45, and I agree find a mu-tron LED based phaser if you don't want the QA dance finding sets🤪


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## swyse (Sep 15, 2022)

MichaelW said:


> I'll update this thread when I get to building. But you can build the Phase II and skip all this crap 😄


I appreciate the recommendation, this wasn't on my radar at all. I just checked that out, and I think I prefer the more subtle phasers, so after seeing it had 6 stages I jumped down the rabbit hole and after a video I found I liked the 2 stage phase 45 more it turns out, but then I saw people comparing it to the univibe and now I don't even know what I want.


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## Chuck D. Bones (Sep 15, 2022)

You can always stagger-tune each phase-shift stage à la the UniVibe.  I could describe the sonic difference between a UniVibe & Phase 90 and effect of stagger-tuning, but it's out of scope for this discussion.  Maybe I'll write something about it in The Boneyard.


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## MichaelW (Sep 15, 2022)

swyse said:


> I appreciate the recommendation, this wasn't on my radar at all. I just checked that out, and I think I prefer the more subtle phasers, so after seeing it had 6 stages I jumped down the rabbit hole and after a video I found I liked the 2 stage phase 45 more it turns out, but then I saw people comparing it to the univibe and now I don't even know what I want.


It's definitely different sound than the Phase 90/45. But I found that I could get a less "squishy" effect with the Depth knob. I used it on the first solo on my Pink Floyd demo. It's definitely there and it's a more filtered sound than the MXR. Which is why I'm building the XC I want the options hahah.


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## Robert (Sep 15, 2022)

MichaelW said:


> Ok, I made a little jig to test SMD JFETs...
> 
> I pulled 10 MMBF5457's and unfortunately none of them were close. VGs off measured in the -.5-.7 range on all 10.
> 
> I wonder if its because they were MMBF5457*LT1*'s. I'm not completely sure what the LT1 designation denotes.



The ones you sent me test around -1.4

How are you attaching them to the through-hole adapter?


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## MichaelW (Sep 15, 2022)

Robert said:


> The ones you sent me test around -1.4
> 
> How are you attaching them to the through-hole adapter?


I'm laying them on the pads then pressing down on them lightly with a pencil eraser.

What are you testing them on?


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## Robert (Sep 15, 2022)

I'm using a DCA75 with SMD adapter.

I tested a few MMBFJ201s similar to how you did it, then tested them again with the SMD adapter and got completely different measurements.


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## fig (Sep 15, 2022)

I have matched sets if needed.


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## MichaelW (Sep 15, 2022)

Robert said:


> I'm using a DCA75 with SMD adapter.
> 
> I tested a few MMBFJ201s similar to how you did it, then tested them again with the SMD adapter and got completely different measurements.


arrrghhhh....that means my numbers are useless...heh....

wait did you solder them then test them?

Or is there some gizmo to hold one of those little jumping beans down?


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## MichaelW (Sep 15, 2022)

fig said:


> I have matched sets if needed.


I have a matched set on the way. But I'm invested, committed, deep down the rabbit hole trying to figure this out hahahah....

But THANK YOU AS AWAYS!


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## MichaelW (Sep 15, 2022)

MichaelW said:


> arrrghhhh....that means my numbers are useless...heh....
> 
> wait did you solder them then test them?
> 
> Or is there some gizmo to hold one of those little jumping beans down?




Ahhh is it one of these gizmos?


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## fig (Sep 15, 2022)

That's the one.



			https://forum.pedalpcb.com/threads/guess-how-many-iv.10997/post-111043


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## Robert (Sep 15, 2022)

Your numbers _might_ be correct, but considering they're a bit out the expected range (and from what I measured on a few from the same batch) they _could_ be incorrect.

Yep, that's the gadget.


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## Locrian99 (Sep 15, 2022)

Not sure if I was just incredibly lucky but I purchased 10 2n5457's from Stompboxparts and got 2 matched sets of quads.   1 set was Incredibly well matched.   I would go this route again rather than buying a matched set.   Theres a vero layout for doing the matching over at tagboardeffects very easy to toss on a breadboard the link to it is in the phase 90 build.


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## MichaelW (Sep 16, 2022)

Robert said:


> Your numbers _might_ be correct, but considering they're a bit out the expected range (and from what I measured on a few from the same batch) they _could_ be incorrect.
> 
> Yep, that's the gadget.


Ok, on the hunt for one that's NOT $50......heh


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## MichaelW (Sep 16, 2022)

fig said:


> That's the one.
> 
> 
> 
> https://forum.pedalpcb.com/threads/guess-how-many-iv.10997/post-111043


I can't keep track of all the contests......


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## HamishR (Sep 16, 2022)

Reading all of this makes me grateful I don't like phasers.


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## fig (Sep 16, 2022)

HamishR said:


> Reading all of this makes me grateful I don't like phasers.


It can become a real FET-ish


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## andare (Sep 16, 2022)

Just found this video helpful


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## Robert (Sep 16, 2022)

MichaelW said:


> Ok, on the hunt for one that's NOT $50......heh



DigiKey has it for $31, you probably won't find one for a much better price than that.    I paid $23 for the socket alone, no PCB included.


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## MichaelW (Sep 16, 2022)

Robert said:


> DigiKey has it for $31, you probably won't find one for a much better price than that.    I paid $23 for the socket alone, no PCB included.


I found it at a couple places for around that but it's the shipping that gets you. Of course now I have to look for some other stuff to make the shipping worthwhile


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## Locrian99 (Sep 16, 2022)

It’s always the shipping…


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## BryGuy (Sep 16, 2022)

andare said:


> Just found this video helpful


Haven’t seen one of Paul’s videos in a while. He seems to have stopped posting them for whatever reason. Really good stuff though.


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## andare (Sep 17, 2022)

BryGuy said:


> Haven’t seen one of Paul’s videos in a while. He seems to have stopped posting them for whatever reason. Really good stuff though.


Yes, so much so that that's Eric, the other owner of the company who's been making videos on the channel instead of Paul. Something about Paul needing to take care of other parts of the business and Eric being more knowledgeable on technical matters.
This channel was my gateway drug into pedal making. I hope Paul resurfaces soon.


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## MichaelW (Sep 17, 2022)

Robert said:


> I'm using a DCA75 with SMD adapter.
> 
> I tested a few MMBFJ201s similar to how you did it, then tested them again with the SMD adapter and got completely different measurements.


Ok, so I have another dumb question.

I soldered 8 of the 10 MMBF2n5457's I had tested earlier with my "pencil eraser" jig (same batch as the ones I sent you) on adapter boards and measured them. Not getting anything close to -1.4v. They were all in the positive numbers....around .4xx to .8xx range.

I'm a bit confused about this JFET matcher board.

This is what the board looks like. Note that it only has 2 unmarked "DMM Test Points".





Here's the schematic...





Again, it only says DMM1 and DMM2.

I've been assuming that DMM 1 is where I should have the COM lead of my meter and DMM2 is where I am measuring the voltage with the red lead of my DMM. Obviously, flipping them gives me negative readings.

Now I'm confused, do I have this backwards?


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## fig (Sep 17, 2022)

I think you need 2 DMMs No, that’s another method, sorry.

I think you my have the leads reversed yes. You are reading the voltage/current from the opamp output that is trying to look like a 10kΩ .


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## MichaelW (Sep 17, 2022)

Ok, I think I may be doing this backwards. Looking again at RG Keen's article and also looking at tagboard effects layouts for a Vero based matcher, I think COM or negative lead of my DMM should be at the DMM2 testpoint of the schematic above. Ugh....stretching my brain here about stuff I don't understand.  Can someone confirm? TIA!


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## Deperduci (Sep 17, 2022)

I see where you might be getting confused, the pin 3 of IC ALSO being listed as positive.. other than the +/_ are the numbers the same when you test either way? If you're getting the same readings numerically but only pos/neg are swapped.. I wouldn't worry to much, the last time I built a pge board I clipped my negative to the "hot" pin of the power jack and the numbers still matched regardless of the +/- inidcator, but that might be my odd ball luck 🤪


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## MichaelW (Sep 17, 2022)

Yah that’s what’s confusing me. But I think I got it now after looking at some of the other tag board layouts.


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## MichaelW (Sep 17, 2022)

Ok just for sh*ts and giggles, I built it out today. Tried the MMBF5457's, didn't work, very light phasing.
Then I tried 4 random MMBFJ201's, slightly more phasing (I think) but still doesn't work.
Sigh, guess I'll have to wait for the matched set. Oh well......
(This was with a 200k trimmer, I couldn't find a 250k.)


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## MichaelW (Sep 18, 2022)

ok, more dumbassery abounds.....I forgot that the 2n5952 pinout was reverse from the 5457's and J201's. 
I turned the 201's around and it works now. Actually pretty decent phasing. (Randomly chosen MMBFJ201's)
I'll try the MMBF5457's again oriented correctly later today and compare.


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