The mystical & magical Zendrive op amp revealed at last (PICS)

Discussion in 'The Stomp Box' started by 11 Gauge, Feb 20, 2014.

  1. 11 Gauge

    11 Gauge Doctor of Teleocity

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    Just as a preamble to what is to follow, I want to point out that these Zendrive pics are of the Lovepedal-produced version - I can make no claims as to how it might differ from the original ones built by Hermida.

    These pics were given to me directly - I did NOT find them on the internet.

    This thread then ties into the following pair of older threads. In one, I made a suggestion to open up a newer Lovepedal Zendrive to see what is now happening with the chip:

    http://www.tdpri.com/forum/stomp-bo...ured-distributed-lovepedal-3.html#post5114129

    ...and another thread, with a specific request as to which op amp to be used, since lots of folks have taken ownership of ZD clones:

    http://www.tdpri.com/forum/stomp-box/443149-what-opamp-zendrive-clone.html

    ...with the crux being that the ZD is a rare example of an op amp/diode clipper pedal where changing the chip can have a sort of profound effect, and Hermida always removed the markings from the op amp. The DIY community has been forced to "guess the magical op amp chip," usually tending towards some ultra-hi-fi component that is rather expensive (3X or more than the cost of what is found in this pedal).

    So, again - this is verification of the op amp as used in the Lovepedal-derived version. I think there is some weight to it, because even though the newly produced ZD's are SMT construction (which you will see), the op amp is a thru-hole part, as are the transistors and at least the 1N34A germanium diode being used. The BAT41 diodes are probably now SMT, the transistors are now sanded, but the op amp chip is socketed, and is clearly a NE5532 - a semi-recent favorite amongst OD stompbox builders of late. AAMOF, when chip substitutions were done in a known ZD clone - the Jetter Gainstage Red - the NE5532 (as subjective as the A/B'ing was) ranked very close to the top with sounding like an actual ZD. The GSR shipped with an OPA2134 IIRC (don't know how this was determined), and it was found to sound "off."

    Even though Hermida very clearly currently has less of a hand (if any) in the actual manufacturing or marketing of his pedals, I can't think he would allow Sean to pop just anything in the latest ZD's. And the choice to use a non-SMT op amp when they are readily available as a SMT NE5532 is an indication to me that there is a stash that is still being used up. There is also visual confirmation that a 1N34A diode is used, which has been claimed to be essential to use in combo with the BAT41 diodes and 2N7000 transistors (as diodes):

    [​IMG]

    So - enough of all that. Pictures of an actual Zendrive with NE5532 op amp:
     

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  2. poiureza

    poiureza Tele-Holic

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    It's quite funny to find a chip socket in a production pedal.
    Doesn't that mean fostering people to try out different op amps ?
     
  3. 11 Gauge

    11 Gauge Doctor of Teleocity

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    BTW - some may want a little more verification that this is an actual LP-manufactured ZD.

    I managed to find a pic of a disassembled one on TGP from some "official Lovepedal thread":

    [​IMG]

    ...and you will note that they now have a blue LED. And - the outer box now has the "Hermida Audio USA" line printed under the pedal name:

    [​IMG]

    And a pic given to me also shows the same thing WRT the top - blue LED, same construction as the disassembled one @ TGP, etc.:
     

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  4. ruger9

    ruger9 Poster Extraordinaire

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    And what's the revelation? Am I missing something? Have we not known all these years what makes a Zendrive tick?
     
  5. 11 Gauge

    11 Gauge Doctor of Teleocity

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    I suppose it could, especially with what is called a "machine socket" used in this instance.

    [​IMG]

    It's more common to find the "dual leaf" style, especially if something is going to be produced in larger numbers, and done with an economical mindset.

    [​IMG]

    I guess if someone has an original Hermida-built ZD, they could A/B this one against it, and then swap a chip out for what they thought was the right one, and possibly witness for themselves the differences, if any.

    It would be sort of funny if folks still concluded that the chip they decided on was the actual correct one. Not that anyone is being duped - just that this is drowned in subjectivity by this point, almost like those who swear that an accurate Klone cannot be made.

    I have no opinion one way or the other. I'm just trying to provide some real world validation in this instance. Sean even said these things would ship with a NE5532 IIRC, but Sean "says lots of things," and I really just want to leave it at that. Here is verification of a NE5532 installed at the factory, signed off by Hermida, in one form or another. So it's as close to the real deal as we are probably going to witness, until someone pulls the glop off an older ZD that didn't have all the markings sanded off the chip (I think that would have happened by now).

    So - it's time for the Pepsi challenge, so to speak. Time to A/B away and come away with some impressions, no matter how subjective.
     
  6. 11 Gauge

    11 Gauge Doctor of Teleocity

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    No. It is a rare instance of the op amp playing a critical role in the sound. This has surprised folks who've analyzed the circuit in painstaking detail - they figured that like most drive boxes with clipping diodes that any characteristics from the chip itself would be masked.

    Even the one thread I linked to has folks with subjective impressions about how different chips will alter the sound a bit. Our own CousinPaul has gigged his ZD clone w/different chips and gotten different results:

    http://www.tdpri.com/forum/stomp-box/443149-what-opamp-zendrive-clone.html

    ...and at that point, it looked like things were leaning to the LM833. Hermida has been known to use that chip in the Tiki Drive, as it wasn't defaced.

    If you go back to what is considered the "de facto" traced schem of the original glopped ZD, the op amp is referred to as being an AD712.

    http://www.mouser.com/ProductDetail...=sGAEpiMZZMvtNjJQt4UgLalm6EXZly/yUkSDRYpZONc=

    That's a $4+ chip. :eek:

    The "suitable substitute" was the OPA2604.

    http://www.mouser.com/ProductDetail...=sGAEpiMZZMtCHixnSjNA6Mrdwin7F8A2umueo293DkI=

    That's a $5+ chip. :eek:

    So like all the other mythological crap that we tend to get bogged down with in all things guitar gear, the world kind of stuck at the two above chips, for the most part.

    After someone did some extensive A/B testing with different chips, something like the TLC2272 was found to be appealing vs. almost all others tested - just seemed to give the best combo of performance.

    So again - this is an instance of a drive box that sonically changes as the chip changes. It's a bit of an anomaly in that way. Something like the Sweet Honey OD is another one - if the OP275 is subbed for something else, the sound changes. Bjorn apparently built the design with the chip specifically chosen from the beginning.

    It kind of signifies how things have changed away from yesteryear - from drive boxes like the TS or even the OCD. Or really so many others. This is kind of borne out with even the chip swapping that folks have done in the Timmy - subtle to no audible difference (their conclusions - not mine).
     
  7. Michael A.

    Michael A. Tele-Afflicted Ad Free Member

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    I would like to buy a ZD clone so I can try this pedal on a budget. Can anyone refer me to one that has a chip socket that would allow different op amps to be tried? Alternatively, if that is unrealistic to find in a cheap pedal, does anyone know one that has the TLC2272 mentioned by 11gauge already fitted? Thanks.
     
  8. cousinpaul

    cousinpaul Friend of Leo's

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    That GE diode looks larger than a 1n34a to me; more like a 1n270. Bad news about the IC. Based on earlier intel, I've been pimping the LM833 as the correct chip. Looking forward to trying the NE5552.
     
  9. stax

    stax Tele-Afflicted

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    I have an AD712 in my clone I also have a bunch I tried inc the LM833 but by the time it takes to swop then in and out I can't really do a proper test so it would be great to get a definitive answer to the best op amp in a Zen question.
    Should I stick the 833 in for now before buying a NE5552 :) I nearly did and then someone on one of the threads linked slagged it off as fizzy so I didn't bother.
     
    Last edited: Feb 20, 2014
  10. MilwMark

    MilwMark Poster Extraordinaire Ad Free Member

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    CBC Pedals The Drive. Used to be $89 before the LP pedals were released IIRC. Now $99. Wonder if that says something about the enthusiasm for the LP version?

    Anyway, seems like a nice guy. Build quality is very high, and the turnaround for me was fast. He sockets the chip. FWIW he uses the AD712. I asked him why and he basically said that it sounded the closest to him, and that he liked it best personally. I had a Hermida ZD and a LP one. Thank goodness you can resell them w/o a loss (or at least I did). I honestly liked the AD712 one best. Can't articulate why. Couldnt' sell the two ZDs fast enough. The CBC has stuck around for a while. Less brash maybe? Smooth w/o being boring?

    Honestly, I think I've concluded the ZD just isn't for me. I'm not a "Dumble" guy - more of a Rat/250 guy I guess. And can never figure out what to do with a 4th control on an OD. Glad I tried it though and may keep it just because it does it's own thing to a degree.
     
  11. 11 Gauge

    11 Gauge Doctor of Teleocity

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    It could be either, or it could be something else. There's a lot of variation WRT appearance with those germies.

    I figured it was the 1N34A because you can clearly see two bands on it, and I've seen 1N34A's like that, as well as some with a green or red band (singular).

    But I tend not to see the 1N270 with a pair of bands - always tend to see a singular band, especially if it's black.

    [​IMG]

    Bear in mind that these things could be getting re-labeled as well. So they could be one or the other, or neither!

    The more important thing with ALL of the diodes and "transistors as diodes" with the ZD IMO is getting the right forward voltages. A germanium diode is going to have a lower Vf in most instances compared to the BAT41 Schottky diode.
     
  12. 11 Gauge

    11 Gauge Doctor of Teleocity

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    I would. It has more in common with the NE5532 than most of the spendy hi-fi application chips that DIY'ers are used to.

    The NE5532 is kind of different in that it has input protection diodes, but the slew rate on the 833 and 5532 are similar - 7V/microsec (833) vs. 9V/microsec (5532). Most of the figures of the two are similar - the NE5532 just seems to expand on the higher-end performance.

    ...And I think it's kind of witnessed in the price, too. The NE5532 is not super expensive compared to most other stuff people have been subbing in the ZD. The 833 is around the cost of the 4558/072/etc. at ~60 cents, and the 5532 is about a buck. If you like the 5532, buy 10 or more and the price usually drops to ~80 cents.

    Even the TLC2272 is kind of spendy at over $2 a pop.

    I have to say - if you look at many pedal builders who have intentions of doing this to make a decent living that very few will go for a pricey chip in a dirt box. Most seem to have experienced that there is no advantage, even if they can get $200+ for a pedal. It's typically the DIY crowd/pedal modders/low-buck cloners who are subbing all this stuff in there, IME.

    And allow me to remind - I really think that in most circumstances, op amp selection in dirt boxes with clipping diodes is steeped in horse puckey beliefs. The ZD is an anomaly that violates this - it's been validated by numerous folks at this point.
     
  13. stax

    stax Tele-Afflicted

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    Thanks 11 Gauge.
     
  14. artdecade

    artdecade Poster Extraordinaire

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    I have no idea what this thread is about - But I do like pictures.
     
  15. ruger9

    ruger9 Poster Extraordinaire

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    I used to sub/swap chips in my ODs... not alot, but several.... I found swapping the opamp almost always made a difference, HOW MUCH of a difference was questionable... I think my Barber LTD (v.1) seemed to change more than other drives I tried to swap chips in... It's so long ago, I don't even remember which other drives I tried this with.
     
  16. JoeNeri

    JoeNeri Friend of Leo's

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    I think it has something to do with how to make sausage, but I'm not really sure.

    Here's a picture, though:

    index.jpg
     
  17. artdecade

    artdecade Poster Extraordinaire

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    Mmmmmm... sausage.
     
  18. surfoverb

    surfoverb Doctor of Teleocity

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    this changes EVERYTHING!




    or not...:lol:
     
  19. Michael A.

    Michael A. Tele-Afflicted Ad Free Member

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    Thanks!

    :confused:

    MilwMark
    I appreciate the referral, but you have almost talked me out of the pedal! I was thinking there might be a $40 Chinese clone.
     
  20. MilwMark

    MilwMark Poster Extraordinaire Ad Free Member

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    Sorry. It's not my intent. Pedal is great. And unique. Just not for me. I think the cheap clone is a Mooer but they seem to retail around $70+ these days. For that I'd rather just pay a few extra bucks and get one handmade. Good luck . . .

    As an aside, I haven't been able to part with it, even though it's not in my top 4. And I'm ruthless about getting rid of pedals that don't work for me. So that says something. It will probably live in my gig bag so I have a drive pedal handy in case one is needed for a quick turn back line amp kind of show. That way I'll have it in reserve and can pull it out once in a while when I get nostalgic or learn something new about my playing, my rig, my ears, etc.
     
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