ta7136 substitution

Some of the System 700 modules use Toshiba TA7136 SIP opamps (datasheet), which are long obsolete and semi-sought after by DIY guitar types because it was used to apparently pleasing effect in a Boss distortion pedal. An eBay seller is trying to get the best part of twenty quid for one.

A while back I bought a bunch from Utsource, and when I eventually got round to making a board to test them I found they were fake…

TA7136 vs fake

…booo.

I made up this adapter for an alternative op amp, ‘cos I don’t think using this particular chip is that important (for now, anyway).

TA7136 to TL071

Here’s a strangely moody photo of the resulting stripboard.

TA7136 > TL071 stripboard adapter

After this I cut one chunk out of one side of the board to indicate pin 1.

I’ve had this working in the 708 noise/ring mod and the 711 output module, and it works fine, although I’ve not had a chance to compare it directly to the 7136.

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12 comments

  1. 1st January 2019Arri says:

    Just curious do you think this could be used in a CE1?

  2. 1st January 2019ua726 says:

    Can’t see any electrical reason why it wouldn’t, though it might be a bit tall to fit in the enclosure? Dunno.

  3. 4th January 2019Arri says:

    I’m actually trying to make a clone of one.
    I was just gonna copy the original PCB and populate it.
    My only worry was the fact that pin 1 and 5 aren’t going anywhere.
    Thanks for the reply!

  4. 4th January 2019ua726 says:

    Nice, good luck with the cloning! If you write it up would love to see a link in the comments here.

  5. 11th January 2019Arri says:

    I’ll probaby write it up when I’m done. 🙂
    I’m planning to use it as a test bed of sorts to see if I can get other more common ICs to play nicely with it.
    If I clone it will you strip-board it hahahaha.

  6. 27th January 2019Steve says:

    Also building a CE-1, planning to use this as a low noise alternative to the Ta7136.

    How can i etch this on a pcb to save space?

    Thanks!

  7. 27th January 2019ua726 says:

    CE-1 frenzy! Well, two of you anyway

    There’s someone who has made an adapter board for the 7136-to-other-op-amp, and it’s available on eBay, but they’re in Idaho in the US, and they’re not super cheap.

    Etching your own boards has always been something I’ve avoided ‘cos of having to deal with the chemicals.

    I imagine you could draw out the schematic from the pin-out I’ve posted, do a layout in Kicad/Eagle/something-else (maybe using a surface-mount footprint for the op-amp to save space) and have ten of them made up in China for the same cost as those other boards, although it might take a while with the impending new year holiday. And then you could sell the ones you don’t need to other Boss chorus pedal fetishists.

    I might even have a go at some stage, I’ve got a couple of things built up that could do with this – if I get round to it I’ll post it here. Don’t hold your breath though.

  8. 20th December 2021Stefan says:

    I didn’t know these were used in the boss distortion.

    I have an Inkel Sherwood mixer that uses these as input stages. I’ve always liked how this mixer distorts when you overload the inputs.

    It all makes sense now 🙂

  9. 7th April 2024Tomo says:

    Nice and simple board, I am going to use it with NE5534 in the output of AIWA ST-9700…Hope for good result.

  10. 14th November 2024Gerd says:

    I cloned the Boss DS-1 several times and tried around a dozen different single opamps in there and must say only the TA7136 gives the right sound. There is a big audible difference between the TA and all the substitutes and little difference between the substitute opamps besides the fact that some need the connection of the TRIM pins to void strange behaviour. It is hard to discribe what I hear but the TA7136 gives a nice hissy throaty quality to the sound. Not only in the overdriven/clipped sounds but also in the low gain clean settings. Anyone, my friends, my partner and probably my dog can hear the difference clearly in the DS-1 circuit. I have no technical explenation and have no idea of what to expect in a system 700 clone. When you build the DS-1 with a TL071 I can imagine you are happy with the result because the pedal will work just fine. Only the ears will judge in favor of the TA if you truely compare. I use the DS-1 clone as a always on pedal on my heavy modded Madamp M15 MK1 now. And yes I am also a huge DIY synth guy that populated hundreds of kits and own designs. Usually opamp types don’t change anything audible. I say if you do a system 700 at least try a real TA7136 even if you have to hunt one down on a very expensive reliable NOS components dealer.

  11. 14th November 2024ua726 says:

    I’m sure this is why there are only 50 or so System 700s left in the world – everyone’s been stripping them for TA7136s to make Boss DS-1s.

    But yeah, I take the point. To be clear, I was going for a functional replacement rather than trying to ape the special distortion qualities of the elderly Toshiba part.

    For what it’s worth, it’s used in the noise generator of the 708 module, and at the end of the phaser and spring reverb sections in the 711 output module on the System 700. It’s also used on the end of the VCF in the SH-5, and on the end of the System 100 VCA.

    From there on I don’t think it makes any more appearances in Roland synths. My current obsession, the System 100M from 1979, doesn’t have any.

    I have got one original floating round the house somewhere. I don’t remember making it much difference either way when I tried it on the end of the spring reverb, but I can imagine it makes all the difference in a distortion circuit where you’re pushing it outside of its design parameters, looking for the idiosyncracies.

    But now you mention it, since the datasheet is available, and there’s even a handy schematic in there – is it tempting to try and make an actual clone?

    Seven dual transistors (with one left over) and a few resistors splatted about, so it might be a bit chunky. Someone on diy-audio has even guessed at the resistor values.

    If nothing else it might make some spectacularly splattery noises.

  12. 19th November 2024Gerd says:

    “Difference in a distortion circuit where you’re pushing it outside of its design parameters”:
    Not only overdriving the preamp but feeding the output signal trough a 150pF directly into pin 1 wich is a trim input that behaves uniquely for these chips.

    So it is even theoretically different from other opamp use cases. Feeding audio in a trim! crazy Japanese Boss designers, wonder if they found that by accident

    The strip layout you made leaves pin 1 non connected and u use self balancing opamps.

    If you go that route my ears liked the PMI OP37GP with pin 1 connected to pin 1 and pin 8 from the opamp connected to pin 5 of the SIL footprint (in a DS-1) but you might want to experiment with that technique especially if the Roland designers drew that in the service manuals.

    “If nothing else it might make some spectacularly splattery noises.” A slightly splattery gain stage with a drippy reverb tank is all the wetness a sound can take. I read you!

    Thanks for the reply,

    Gerd

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