phase 45 opamps

[Fndr8875]

i know opamps are interchangeable in alot of situations, i always see tl072 as opamp listed for phasers, mxrs at least. I know the script/original phase 90 used 6 lm741s. I have some lm1458s (dual lm741s) are these interchangeable with the tl072s for a phase 45,  is a fet based opamp required? i guess i dont know since the originals used lm741s. Also im about to order some matced fets, are matched fets usable in any situation that calls for matched fets, or do they have to be matched in a certain range differently if it is a phaser vs say a tremolo or other modulation pedal that calls for matched fets. ive read stuff on matching fets and i dont really understand all the formulas and everything, i think matched fets are matched fets, but not sure if the fet based opamp is required, when originals didnt use them. i know they used different fets anyway, makes my head spin with all the info there is and so just looking for some advice. Also the veroboard site that im basing build off of shows 500k linear pot taper, i know (or least think) that 500k C pot is used, which taper would be better , using the linear taper or 500k audio pot wired in reverse? thanks for any replies ive got a ton of pots , resistors, opamps, everything but seems like when i want to build something specific im always missing a key component. I do my best to research and breadboard things , but like in this situation i dont have any matched fets so i couldnt even begin to test it out.

[smallbearelec]

I have some lm1458s (dual lm741s) are these interchangeable with the tl072s for a phase 45

Yes.

are matched fets usable in any situation that calls for matched fets, or do they have to be matched in a certain range differently if it is a phaser

The seller should tell you what they are matched for. The key parameter is the Vp, the voltage that turns the device off. You want this to be well under half the supply voltage (R. G. Keen suggested -3.5 volts max when I asked his advice), and the Vp of the two devices should match within 10 millivolts.

which taper would be better, using the linear taper or 500k audio pot wired in reverse?

Linear taper will be "tight" at the clockwise (high speed) end. Audio will give you better control, but the direction of control will be reversed. Wiring an audio taper pot in reverse will not be ideal; if you want good control of speed and natural direction of control, order a reverse audio (C taper) pot.

[Fndr8875]

well i ordered a matched set, plus 1 2n5457 from 1776 effects, it is for their cardinal tremolo, was 7 bucks shipped and at about 1 apiece i couldnt justify spending 20 bucks or whatever and then having to build a little circuit to match them, escpecially with my limited knowledge. I was skeptical because they have the DOD reiissue phaser on sale from 100 bucks to 39 bucks at muscians friends, which i think itll end up costing me 30 for the parts and i really enjoy building but ive been overding it( keep reading about my last eqd hummingbird build) and just want a working phaser...... this is from the build doc about the matched fets:


➤ Important: Q2 and Q3 must be MATCHED so that they can be trimmed to the same
voltage for correct harmonics and amplification. You want to find two 2N5457s that will
bias to approximately 6V with the same amount of resistance on the drain. The final
drain voltage will be set using the bias trim pots, so you don't need to worry about any
other characteristics. The easiest thing to do is socket at least one of the transistors (or
breadboard Q2, R5, R6, and use a 2.7K in place of the trimpot), set the trimpot to
halfway, and measure the drain voltage. Then you simply have to swap transistors until
you find any two that have the same drain voltage. Anything within a few tenths of a volt
is fine. If you simply don't have access to enough FETs to match a pair closely enough,
in a pinch you can adjust R7 (use a socket) to set the gain of the treble band.

I guess i need to email them to get the specs. I thought that if they were matched they would work in the circuit, then you would use the 250k trimpot , and set 500k pot to mid way and turn trimmer slowly until you get an even rise and fall.

I wish you had c500k pots in 12mm,  but its not like ill be hurting for room its a madbean smoothie made for 1590a , and i just recieved a 1590b for this build. the hammond black ones have a little different finish than the other colored ones and it came with black screws. guess ill be making an order for a c500k pot, and the Large boss type know in Orange plus a 250k trim pot from smallbear. I wish you had some larger pics of ur knobs, that Orange fluted knobs looks sweet. Oh i got that EQD perc trem working with 2n2646 i ordered from you. ugh, man, i became obsessed with getting it to work kept getting tiny solder bridges  bc the 20589 and 2n5457 were laid out in a straight row wiht the smallest sliver of space between pads, so 8 etched boards later its working haha. my soldering skills leave a lot to be desired

really appreciate your input on the opamps(i ordered those from you as well so i know theyll be on point) i didnt see any matched fets on your site or i would have just ordered them from you seeing as i need the trimmer, c500k pot, and most importantly Big orange knob haha.