Author Topic: Matching fets/Galacticon phaser  (Read 1074 times)

devilsnight

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Matching fets/Galacticon phaser
« on: January 03, 2017, 10:30:27 PM »
 So I built a galacticon phaser tonight. I'm wondering if anyone knows, what is the proper way to set the bias pot? I wouldn't think by ear? It doesn't seem to make any difference where I set it which leads me to question #2..

 I built RG Keens jfet matcher last night. Not realizing there is an Updated jfet matcher also (DOH!) Am I just looking at the VGS numbers to match a set? I have to read his article again on matching fets and let it sink in... The set I matched is  obviously not close enough as the phasing is very slight. I ended up writing off a bag of 5457's I bought from tayda because the readings were so much lower than the rest but, after reading keen's article It seems like those should be fine if there are 2 that are close? I might break down and just buy a matched set. I'd rather figure it out myself though. I dunno, any thoughts greatly appreciated!

Stomptown

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Re: Matching fets/Galacticon phaser
« Reply #1 on: January 03, 2017, 11:49:34 PM »
#1. Yes. Setting the trimmer by ear is the way do do it.  There is a small range on the trim where the phasing will be present and you find the sweet spot within that range.

#2. Yes. You need a pair with matching Vgs. I've had good results with matched pairs above 120Vgs. 


devilsnight

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Re: Matching fets/Galacticon phaser
« Reply #2 on: January 04, 2017, 12:35:08 AM »
Excellent! Thanks for the info.

 For the sake of asking, Are there any reasonably priced fets still available that a person could buy in quantity for matching sets?? Through hole components are getting harder to find these days! Jon had made mention of the 2N5952 as working great in a phaser but again pretty hard to find.. Would the 2N5951 work just as well? I know smallbear and such carries these things but for a price I'd rather not pay.

midwayfair

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Re: Matching fets/Galacticon phaser
« Reply #3 on: January 04, 2017, 09:25:56 AM »
Excellent! Thanks for the info.

 For the sake of asking, Are there any reasonably priced fets still available that a person could buy in quantity for matching sets?? Through hole components are getting harder to find these days! Jon had made mention of the 2N5952 as working great in a phaser but again pretty hard to find.. Would the 2N5951 work just as well? I know smallbear and such carries these things but for a price I'd rather not pay.

Smallbear at 50c each is pretty much the best deal going. You will not find through-hole cheaper and if you do then you should consider that they're likely to be fakes or seconds and you'll probably end up having to buy twice as many to get matches anyway. If for some reason Smallbear's 50c each price is too high for you, I guess you could pay Mouser's 93c each at 10. (If you want a hundred, you only pay 78c!)

If you don't want to buy enough to make your own matched pairs, then they also sell matched sets for ~$5 each. That's consistent with pretty much everyone who makes matched sets for phasers.

The 5951 has some overlap with the 5952 but the top of the bellcurve is quite a bit off. Again, you'd probably have to buy a bunch more to get proper matches.

If you want to take a risk that you might end up with a pile of out-of-spec parts that it's possible won't yield any appropriate matches, then Tayda is a better bet than E-bay. They're 32c each there. If you figure 15 will yield a couple pairs at least but 10 might not yield any and 20 is probably an ideal number when you aren't sure how consistently they will be (hah! consistent FETs!), you will save a grand total of $3.60 to roll the dice.
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flanagan0718

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Re: Matching fets/Galacticon phaser
« Reply #4 on: January 04, 2017, 05:24:51 PM »
Like Jon said you might be better off ordering a pre-matched set. $5 from small bear is pretty cheap. GuitarPCB sells them too, not sure what he charges tho.


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devilsnight

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Re: Matching fets/Galacticon phaser
« Reply #5 on: January 04, 2017, 10:10:28 PM »
Thanks Jon, thats pretty much as I expected... It's not that 50 cents a piece or $5 a pair is unaffordable to me, I'm thinking long term. I would like to do this for awhile! Say I want to build a phaser 2 years from now, are they going to be a dollar a piece/10 for a matched set? Who is to say... It would be nice to "stock up" on some of these components before they are gone for good. I'm going to go shuffle through the rest of my jfets and see if I can find a better match. Will keep you guys posted what I find. Thanks!

Torgoslayer

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Re: Matching fets/Galacticon phaser
« Reply #6 on: January 04, 2017, 11:26:44 PM »
I would like to do this for awhile! Say I want to build a phaser 2 years from now, are they going to be a dollar a piece/10 for a matched set? Who is to say...

There are plenty of great sounding OTA and optical based phaser projects out there too. No matching needed.

devilsnight

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Re: Matching fets/Galacticon phaser
« Reply #7 on: January 04, 2017, 11:37:06 PM »
Ya. I know. My board archive is full of p45 and p90 work alikes though!

midwayfair

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Re: Matching fets/Galacticon phaser
« Reply #8 on: January 05, 2017, 08:44:01 AM »
Thanks Jon, thats pretty much as I expected... It's not that 50 cents a piece or $5 a pair is unaffordable to me, I'm thinking long term. I would like to do this for awhile! Say I want to build a phaser 2 years from now, are they going to be a dollar a piece/10 for a matched set? Who is to say... It would be nice to "stock up" on some of these components before they are gone for good. I'm going to go shuffle through the rest of my jfets and see if I can find a better match. Will keep you guys posted what I find. Thanks!

Long-term, $1 for through-hole transistors of any sort isn't out of the question. They are going the way of the dodo, though we might all be drowned in rising sea waters by the time they dry up. (Look how long Ge transistors from the 50s and 60s have lasted.) You can still use SMD JFETs -- and there's plenty of time, while through-hole is being phased out, to get good at soldering SMD. It's a bit of a pain to solder legs to them to make testing go quicker, but some people have made adapter PCBs (which honestly I think is just as much work). I'm not sure what the equivalent part number is. And though Mouser stopped carrying through-hole for a while, all of a sudden they have them again, and in VERY large numbers, you can get them for less than 50c each right now. Who knows, the price may go back down again.

I know a dollar's a dollar and all that (and believe me when I say that I'm as cheap as they come -- I have literally said out loud "I'd rather have $5 than a meal right now" recently), but I still think that ultimately it's peanuts compared to the overall cost of a single solid build. (Production pedals will just use the SMD parts because they don't have to hand-solder the transistors.) If cost is a sticking point then there are other ways to make a phaser that are marginally cheaper overall (OTA and optical), which was already brought up -- you should try them anyway! The Stage Fright and Mutron II both sound amazing.
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devilsnight

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Re: Matching fets/Galacticon phaser
« Reply #9 on: January 06, 2017, 02:03:44 AM »
Right on! I like that the galactica gives you the option for through hole or smd. That seems like an excellent option at this point. I accidently ordered smd tl072's recently.. I feel like I'll need some kind of magnifying glass rig to get into that, Probly should look into that though, just because. On the other hand my last 2 builds were mb wigl's. Turned out great. I'd been previously somewhat intimidated by optic/vactrols, just for a lack of understanding. Have had great luck building my own though.

 As far as the galactica goes. I need to build the updated jfet matcher and give that a try. I ended up just blindly swaping in transistors. I ended up with really good depth but it's more of a vibe/tremolo sound. Which is really awesome followed by an out of sync tremolo, reverb and delay :) but I do want to get it right. Hope to have some time this weekend