Sunday 3 February 2013

Ibanez MT10 Mostortion

Request, without in/out butffers.



15 comments:

  1. The 3260 is a tough find. I just ordered two from eBay at 7.50. And that looks like a Bogo price. I will build this when they come in. I am thinking this would be nice in the same box as a timmy with a 3pdt switch to switch the order of the affects.

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  3. Only relatively suitable alternatives i found are MC33502 and AD882. There's also CA5360 which should be suitable.
    You could check out the reference guide: http://www.allxref.com/ad/ad822.htm

    But i think nothing will sound the same as CA3260.
    +m

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    1. ..although, the pinout is common with all the basic dual opamps, so i guess those should work equally well. But that means that it's not really MOStortion...
      +m

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    2. Hmmm, so that means with the ca3260 you could make a MOScreamer too...

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  4. Just finished this and it works so you can verify it after fixing just a couple things. The Treble knob works backwards so switch 1 and 3 on that. Also looking at the schematic it looks like that 4.7k should be another 47k I believe. And lastly there is 1 trace cut that didn't make it from the full image to the just the cuts and jumper image. It's the cut upper right of the 1uf electo.

    It's late here so I only tried it with my noisy crickett (build from your layout!) and it seems a little brighter than I remember this pedal being and the bass knob doesn't seem to do much, but my noisy crickett has a 5in speaker in it so....

    I put a 4558 chip in it and plan to do some more swapping in the morning when I can be loud again. Many thanks!!!

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    1. Fixed. Thanks for letting me know. And of course, for verifying!
      +m

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  5. Anyone know if there's a general problem with the Ibanez 10-series pedals? I have two; the MS-10 Metal Charger and the BS-10 Bass Stack that both seem to have a similar problem. Seems like a loose connection or something; sometimes the pedal loses alot of the signal and cuts really low. Both the bypassed signal and the effect. You think it's the jacks that's been worn out or is some part in the input stage gone bad?

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  6. I've just finishes it, with a CA3260, and it seems to work good, excepting one problem: when I replaced the 4 diodes 1N4148 with 2 diodes BAT41, I've heard a lot of clean signal and, very weak, a distorted signal (something like a Gretsch Controfuzz)!!! After that, I put 2 blue diffused LEDs and it sounded better, but the clean signal remains...I have this problem for almost all combinations of diodes that I tried...when I put the 1N4148s back, it sounded OK again:)

    I've built over 50 different overdrives/fuzzes/distortions until now, but this is the first time when I have this problem...anyone has any ideea why?

    Best regards and thank you for all your fabulous work!

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    1. I rechecked the layout against the schematic and I found some mistakes in it:
      1. the 220nF cap (after the 2.7K resistor) it's wired to ground, instead of Vb (this thing can be very easy repaired: move the bottom pin of the cap one strip above)
      2. the volume 1 is wired to ground, instead of Vb, too (this thing can be repaired easy, too...)

      After I repaired it, it sounded very good :)

      Moreover, the input and output caps are NP in the layout, while in the schematic are electrolytics, but I think that isn't a problem.

      Best regards!

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    2. Fixed the gain setter 220n. That was my bad. Thanks for noticing!

      But. Your circuit shouldn't work at all with volume 1 to vref. Without the output buffer and volume 1 to vref - you're amp will see ~4.5V of voltage instead of the signal. That's why the volume 1 always goes to ground if there's no output cap or a buffer after it. Schematic has volume 1 to vref - but it also has a buffer after the volume control.
      +m

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    3. Thank you very much mirosol!
      I did the mods which I posted above at 1 AM, so I tested the results at a very low volume, using 2 diodes BAT41, but I am sure that all pots worked...the volume was the first, of course :)
      Now I am in a holiday, but when I will come back, I will do more tests.

      Best regards!

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    5. Very strange thing: with Volume 1 to Vref the circuit works very well, but it has too much output and it goes to feedback very fast...in conclusion, I rewired the Volume 1 to ground, as you said.

      The main problems remains that if I use 2 BAT41, I have a lot of clean signal at the output!!! Why??? Is something special with this CA3260? I never heard something like this before!!!

      Thank you all!

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    6. I recheck all, using other op amps and the problem remains...the same strong clean signal is present after the first stage, before the tone stack (when I use BAT41)...maybe the missing buffers is the source of this behaviour?

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