Tayda OP07CPs?

[mkstewartesq]

Now, I remember reading right when I joined this forum to avoid ICs from Tayda - so while I did order some before I joined this forum, I immediately segregated them as “last resort” ICs and only use ICs purchased from Smallbear, StompboxParts, GuitarPCB, etc.

But I was building a verified stripboard Fat Rat and needed an OP07 so threw a few OP07CPs in my Tayda cart because they were relatively inexpensive and I was ordering a lot of other stuff at the same time. That build ended up sounding like shit (honky, kind of like a half cocked wah, sputtery in the decay, and not much gain to start with and less and less gain the higher you moved in the frequency range/up the neck). I chalked that up to maybe me screwing something up in the build.

So I did a stripboard build based on the JHS Triad Distortion, which is basically a Rat, and got the exact same results. I double checked all my values and placement (I’m actually a nerd who checks all the values on the multimeter BEFORE I even put them on the board) and I’ve sawed between the tracks to eliminate possible shorts so much that I can now roll up the board like a bamboo mat.

So I tried putting a TLO71 since it is at least pin-compatible, and actually got some really good sounds, and at least about the level of gain and distortion I would expect from a Rat, even if not the exact sound. But none of my OP07s sound good at all.

I’m resigned to giving up on the stripboard and will just buy a Muroidea or Triad board and buy some OP07s from Robert then or elsewhere if I’m placing an order. But has anyone had any issues with these chips from Tayda, or any suggestions on how I can test them so that if they are in fact bad I can let Hugo know?

Mike

 

[Cybercow]

I've had issues with chips from Tayda and no longer rely on Tayda as a source for any sort of chip. They apparently make bulk chip purchases from questionable sources.

Likely the OP07s from unreliable chip sellers are often rebranded LM741s, LM748s, LM201s, LM301s or similar. I've found only genuine OP07s or LM308s to reproduce an authentic Rat sound. 741s, 201s & 301s sounded like you described - honky, sputtery and/or farty. And while a TL071 will work, its slew rate (0.3V/µs) is much than that of an OP07 or 308 (0.5V/µs). The TL07x series are FET input devices with a very high input impedance; while the OP07 & 308 are low impedance BJT input devices. And as far as I can make out from reading and testing, the human ear cannot detect the effect of slew rate differences on opamps above about 0.35V/µs. IMO, the Rat circuit obtains a good portion of its unique sound from the 0.3V/µs slew rate where the higher audio frequencies are less defined and obsequiously distorted.

FWIW, here is my growing list of PIN-FOR-PIN Replacements for single opamps:
LF351N - Slew = 13V/µs; FET
LF356 - Slew = 12V/µs; FET
LM201 - Slew = variable; BJT
LM301 - Slew = variable; BJT
LM308 - Slew = 0.3V/µs; BJT
LM148 - Slew = ~0.5V/µs;BJT
LM4250 - Slew = variable; BJT
LM709 - Slew = 0.25V/µs; BJT
LM741 - Slew = 0.5V/µs; BJT
LM748 - Slew = 0.5V/µs; BJT
MC1439 - Slew = ~6V/µs; BJT
MC33171N - Slew = 2.1V/µs; BJT
MCP601 - Slew = 2.3V/µs; MOSFET (In & Out; 6v MAX)
MCP603 - Slew = 2.3V/µs; FET
MUSES03 - Slew = 35V/µs; FET (very expensive)
NE5534 - Slew = 13V/µs; BJT
NJU7031 - Slew = 3.5V/μs; FET
OP07CP - Slew = 0.3V/µs; BJT
OPA134 - Slew = 20V/µs; FET
OPA1642 - Slew = 20V/µs; FET
OPA205 - Slew = 4.0V/µs; FET
OPA602 - Slew = 20V/µs; FET
OPA604AP - Slew = 25V/µs; FET
OPA1641 - Slew = 20V/µs; FET
TL061 - Slew = 3.5V/µs; FET
TL070 - Slew = 18V/µs; FET
TL071 - Slew = 13V/µs; FET

 

[owlexifry]

has anyone had any issues with these chips from Tayda

i’ve bought a couple OP07s from tayda about a year ago or so.

first rat build a while ago sounded fine.
then i got some NOS LM308HZ opamps to try out.
built a rat circuit on a breadboard to test them out and i compared them against the tayda-sourced OP07 - it didn’t sound that drastically different from the LM308HZ, so i assume there was nothing wrong with those OP07s.

(sorry, i don’t have any advice on how to objectively test/measure for specific parameters)

tayda-sourced opamps seem to be hit and miss, ive not encountered any problems yet, but im now starting to source all my opamps and transistors from mouser for ease of mind.

 

[darwin999]

But has anyone ... any suggestions on how I can test them so that if they are in fact bad I can let Hugo know?

Very nice of you to let Hugo know.

For one, check the datasheet from that manufacturer, and look at the printing and case for possible differences. Hopefully you can tell the manufacturer from the text or logo. Logo lookup is here:

https://how-to.fandom.com/wiki/How_to_identify_integrated_circuit_(chip)_manufacturers_by_their_logos/all_logos

IC Identifizierung Schaltkreise

IC Identifizierung nach Hersteller

info.electronicwerkstatt.de

IC Logos of manufacturers | Elnec

IC Logos of devices supported by Elnec programmers. Logos of IC manufacturers.

www.elnec.com

If you can't figure out who the mfr is, email a pic to Hugo and ask him.

Next, you could look for basic quantities that could be measured, such as input impedance. TI's datasheet for the OP07 (https://www.ti.com/lit/ds/symlink/op07.pdf?ts=1742266797138&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FOP07) lists the input resistance as being ≥7Mohm and typically 33 Mohm. Other basic quantities might include quiescent current draw (put it on a breadboard and short the inputs, measure current on supply line(s). Etc. And likely others here (including Mr. Bones) will have good or better recommendations.

Good luck!

In my experience, I've had good luck with Tayda for transistors and ICs, although if I can get fancier ICs from an official supplier like Mouser/Robert/etc I definitely prefer to do so.

edited: small tweak on wording...

 

[Paradox916]

I built a parentheses ( EQD life) about 3 years ago using an OP07 I sourced at the time from tayda and later A/B it WTH a NOS 308 I got, there was an audible difference but it wasn’t much, possibly even perceived, like @owlexifry Didn’t take any measurements just by ear, it’s still in that pedal and I still think it sounds just as good as my rat clone with the NOS 308… but of course YMMV, that said I there is a fair chance it would work just fine.

 

[Cybercow]

". . .how I can test them . . ."

Mike

I found this a few years ago. (Took me hours to find where I copied it.) An OP07 should test/measure similarly.

 

[finebyfine]

I’ve stopped buying ICs from Tayda. LCSC has plenty of cheap options of industry standard op amps made by various chinese manufacturers but I implicitly trust them more because they aren’t pretending to be the original manufacturer. I’ve had no issues with them whatsoever. I’ve bought various OP07s even. YMMV for cleaner circuits

 

[jimilee]

I get all my parts from @StompBoxParts almost exclusively. I no longer order from Tayda. I get other parts from @PedalPCB.

 

[Erik S]

I get all my ICs from Tayda

 

[jwin615]

I found this a few years ago. (Took me hours to find where I copied it.) An OP07 should test/measure similarly.

View attachment 92551

No connection on pin 5 isn't true for an OP07 iirc.

 

[Cybercow]

No connection on pin 5 isn't true for an OP07 iirc.

 

[mkstewartesq]

Thanks all for your help so far.

@Cybercow - I have a tester but does that diagram mean that I need to insert components two or between certain pins (like the reference to a diode and resistor to pin 7)? I don’t have a bread board or anything like that.

Also, to all, just FYI – Tayda just list the manufacturer as “various“ and I don’t see any logos on the chip – attached is a picture of one I received. There is a very faint possibly heart shaped design to the left of the number but it is so faint I honestly can’t tell if it’s a logo or just the pebbled surface of the chip.

Thanks again!

Edit to add – I know it looks like the chip isn’t pushed all the way into the socket – it normally is, I just hadn’t yet pushed it all the way back in when I put it back in place after testing the TLO71.

 

[owlexifry]

Thanks all for your help so far.

@Cybercow - I have a tester but does that diagram mean that I need to insert components two or between certain pins (like the reference to a diode and resistor to pin 7)? I don’t have a bread board or anything like that.

Also, to all, just FYI – Tayda just list the manufacturer as “various“ and I don’t see any logos on the chip – attached is a picture of one I received. There is a very faint possibly heart shaped design to the left of the number but it is so faint I honestly can’t tell if it’s a logo or just the pebbled surface of the chip.

Thanks again!

Edit to add – I know it looks like the chip isn’t pushed all the way into the socket – it normally is, I just hadn’t yet pushed it all the way back in when I put it back in place after testing the TLO71.

View attachment 92559

without a manufacturer marking, might be suspect…

this the one that went in my first rat build

tayda sourced, clearly marked as made by texas instruments

 

[jwin615]

View attachment 92558

I meant electrically, but I was wrong. So. IIDRC?
Was thinking about this video

I'll note. I've measured real 308s that measure differently than his his measurements. BUT, this is a good way to see if you have a rebadged 741 etc

 

[mkstewartesq]

I meant electrically, but I was wrong. So. IIDRC?
Was thinking about this video

View attachment 92576
I'll note. I've measured real 308s that measure differently than his his measurements. BUT, this is a good way to see if you have a rebadged 741 etc

Thanks for this. I used it and, like you, while my numbers didn't match exactly, it did confirm that pin 5 is disconnected from the other 7 pins.

I ordered some OP07s from StompBoxParts (along with a lot of other stuff I didn't really need, just to justify the shipping cost) so we'll see if they make a difference. If not, and this issue arises somewhere else in my builds (weird, since the same issue with two different layouts), well, then I'll have a shitload of OP07s when I only needed 1.

M

 

[Cybercow]

Thanks all for your help so far.

@Cybercow - I have a tester but does that diagram mean that I need to insert components two or between certain pins (like the reference to a diode and resistor to pin 7)? I don’t have a bread board or anything like that.

The diodes that appear in that diagram are just to show what sort of behavior should be expected when measuring with a DMM (or GM328) in Diode mode. The numbers next to them is the approximate Vdd between the chip's pins.

 

[mkstewartesq]

The diodes that appear in that diagram are just to show what sort of behavior should be expected when measuring with a DMM (or GM328) in Diode mode. The numbers next to them is the approximate Vdd between the chip's pins.

Thanks. Assuming I'm even doing it right (a big assumption), when testing pair of pins using my multimeter in diode mode, most of my readings for my OP07 seem to be about half of those shown in your diagram for the LM308.

 

[jessenator]

I got some in 2023 and they look legit. Sound legit anyway. Sorry you got a bad batch… I couldn't quite make out the whole of your chip. I had to take photos at an extreme angle with "flashlight mode" turned on.

Here is the marking on my TI specimens:

Much more coherent than the fake TL072s I bought.

Compared to a vtg version (courtesy of jwin):

obviously a different marking method (silkscreen) entirely.

Other, contemporary (to the first one) TI markings (TL072 is for sure from Mouser):





Like I said, if it's a fake, it's much better than the others I accumulated:

 

[mkstewartesq]

I got some in 2023 and they look legit. Sound legit anyway. Sorry you got a bad batch… I couldn't quite make out the whole of your chip. I had to take photos at an extreme angle with "flashlight mode" turned on.

Actually, that’s a great suggestion. The lettering on my chip is engraved but not filled in with any colored ink – but here’s what shows when taking a picture with flash at an extreme angle so that the light catches in the engravings.

 

[mkstewartesq]

I’m just following up to say that I got my OP07s from StompBoxParts and, whatever the issue is with my build, it ain’t the Tayda OP07s.

The chips from StompBoxParts definitely look a lot more legit – the markings on the chip are clear, bright and easily readable. But the sound of the pedal has improved only marginally and even that might be my imagination. So I don’t know where to go from here – I’ve checked the values and placement about 50 times now, triple cleared for possible shorts, etc. with no improvement. So while I can’t say obviously for sure that there are no issues with the Tayda chips, I have to assume they are legit because other of the same chips from trusted sources don’t sound any better in this build. So apologies if I created apprehension on anyone’s part about buying this chip from Tayda.

So I’ll just ditch the strip board and buy a PCB from Robert this weekend – and pray that it sounds world’s better than my strip board build, otherwise I’ve been mishearing what a Rat sounds like for 40 years.