Tuesday, 10 June 2014

Leegazzy - Carvin Legacy Emulator

Request, layout for the Leegazzy Carvin Legacy emulator by Antonio Pelaez.

I've shown a big axial cap as a filter in this one because there was plenty of space at the top and I have them exactly the size shown, but as always it will work just as well with a radial electrolytic, and you can just solder it between rows 8 and 9 (9V and ground) rather than spanning half the board.






70 comments:

  1. Good morning.
    If a 'stand-up' cap is used, the +leg goes to row 8 and the 'stripe' leg goes to row 9. Correct?
    jeff

    ReplyDelete
    Replies
    1. Leave the positive lead where it is connected, connect the negative lead one row above it.

      Delete
  2. Mark, you're on fire, so many greats circuits to build ! :)
    And on a side note, I like having all the wires on the same side.
    I need to stock on 9mm pots to fit this one in a 1590B box

    ReplyDelete
  3. It'll take up less room in a 125b

    ReplyDelete
    Replies
    1. Actually 1590B is smaller than 125B

      Delete
    2. Oh. That's the smaller box.
      I always use a 125b and put the 9v and in/out jacks up front. It takes up a lot less room.
      I never put a battery jack in em either.
      Can you tell me how to post pix on this sight?

      Delete
    3. It doesn't let you embed in the comments, so I usually just post to photobucket or tinypic and then post the link here

      Delete
  4. lvlark;I dont' know how ya did it but, the last 2 requests i ask for you have on the very next day.you truely amaze me.thank you very much for this and the diefet.How long does it usualy take for you to make up a vero from a schematic?

    ReplyDelete
    Replies
    1. It depends how well the layouts flow. This one took me about an hour, the Diefet a bit longer because it's a bit more complicated. Sometimes if the schematic is complicated I'll do it over several session because after a while things can become clouded, but having a break and then coming back to it I can often think of ways round problems which totally escaped me before.

      These emulation circuits are really easy actually even if they do look quite complicated. They're just like slightly larger Big Muffs and so with the JFETs half way between the 9V and ground rows, it's really easy to place the components without having to overcome any real obstacles. I'm also quite into them at the moment which is why I'm churning them out quickly :o)

      Delete
  5. Wow~! and after checking youtube demos of this one I see this over on the right LOL
    ISP Technologies Theta Guitar Preamp Pedal https://www.youtube.com/watch?v=ztNLNG-LRnc
    AnyWHo!... Leegazzy added to the to do pile :-p

    ReplyDelete
    Replies
    1. the theta pedal is sick sounding. The tone at the beginning has "Satriani's flying in a blue dream" written all over it

      Delete
  6. Presence 2 And volume 2 to output? That's kind of odd, isn't it?

    ReplyDelete
    Replies
    1. The tone stack is slightly odd too in parts. But

      Output > Presence pot > 2n2 > Ground

      just means there is a variable high pass filter at the output

      Delete
  7. Would using 50k trimmers inhibit the performance of this pedal? I chk'd volts changed trannys but still get a 50% power sound out of this. No solder bridges, all parts correct ...is it the trimmers?

    ReplyDelete
    Replies
    1. You need to use your multimeter, positive side to drain, negative to ground, and turn each trimmer until the DC voltage reading you get is around 4.5V. See what the upper and lower voltage is of the trimmer, and as long as you can get around 4.5V then they are big enough.

      Delete
  8. Hopefully building this in the next few days

    ReplyDelete
    Replies
    1. IvIark,

      I as building this using Bourns 1/4" blue trimpots but their footprint is a bit too large and they cover some of needed holes for caps and resistors.

      What trimpots are you using?

      Delete
    2. i had your problem but with a more easy to mod layout.
      so i didn't have to wait for the right trims to come
      but...
      3 days ago i got these in my door!
      http://www.ebay.co.uk/itm/251054168473?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
      very good trimpots.

      Delete
  9. I just finished putting everything together and.. A problem. I can't seem to bias q2 and q3 any lower than about 6v. I'll try some other 5457 transistors, but I don't have many more. I'll also give some j201's a shot.

    ReplyDelete
    Replies
    1. Something is still wrong. I don't know if it's my build or what. I can bias it properly with j201 transistors, but there isn't a lot of gain on tap.. Not like in the demo videos. It doesn't sound saturated at all, more like an overdriven clean channel.

      Any thoughts?

      Delete
    2. No thoughts but I can report back that Ive had a go at making this and I get the same results as you, ie mild overdrive.

      Delete
    3. Hi all.
      I installed the 47u can cap upside down. Before I rebuild the whole thing can anyone tell me if doing that fried anything?
      jeff

      Delete
    4. No, all it could have damaged is the cap itself

      Delete
    5. Thanks Mark.
      Is this verified or am I flying blind?

      Delete
    6. This comment has been removed by the author.

      Delete
  10. Has anyone else had success with this build?

    ReplyDelete
  11. I tried this build tonight using some extra SOT-26 J201s that i had with adapter boards and.... it works! at least it sounds much more like the video than it did before.

    some comments:

    1. presence is backwards. pres 3 should be pres 1.

    2. i can't bias q3 to 4.5V... this might be because of j201 vs 2n5457.

    3. treble and bass act weird. in the last 5-7 degrees of rotation when maxing treble or minimizing bass the signal cuts out completely. not sure what's going on here...

    4. this puppy loves 18V :)

    i'm going to try some SOT26 2n5457 jfets when i get my next mouser order in and see how that works.

    ReplyDelete
  12. Had this one on my list for some time and built it today. Consider it verified :) ! As Tim mentioned above the presence pot is backwards. This one is a really great od/dist, very versatile and dynamic. Thanks again, Mark!

    ReplyDelete
    Replies
    1. Excellent, nice one buddy. Was starting to worry about this one :o)

      Delete
    2. Hi Heiko! Are you running it on 9v?

      Delete
    3. I`m running it at 18V. Works fine at 9V though.... More dynamic and "concrete" at 18V, as (almost) always :)!

      Delete
  13. This circuit can be very trebly, so I recommend a 250K presence pot. And a 1M log treble pot gives a better taper (for me). Oh: this puppy *prays* for 18V.
    For all those, who have issues (not enough drive...): adjust the trimmers by ear and do not stick too much to the 4,5 volts. Jfets can be very dodgy these days ;-)

    ReplyDelete
  14. Well done guys ! I am the one who plays in the video.. I appreciate very much your new optimized layout (mine was not optimized, but the pedal sounded anyway, as you can hear in the video)

    ReplyDelete
  15. Ligazzy and stigazzy ... :-) complimenti Demy !!

    ReplyDelete
  16. My first build ever. It started to produce sound after using 12v supply. With 9v even biased on 4.5 it just sounds like weak overdrive. Biased by ear, the same result.

    If I bias by ear on 12v it sounds like Fuzz pedal with saturated low end.

    ReplyDelete
  17. This comment has been removed by the author.

    ReplyDelete
  18. i wonder if 47k trimpots are sufficient for this circuit.

    ReplyDelete
  19. Guys, please post your modifications if any were made. On 9v it sounds clean to crunch.

    ReplyDelete
  20. This comment has been removed by the author.

    ReplyDelete
  21. Hi guys! Any ideas how to make it 9v workable? :)
    Thank you!

    ReplyDelete
  22. My build woorks fine at 9V, tons of gain! Try adjusting the trimmers by ear, find the spots where the signal is loudest and go on from there. I didn´t measure my voltages but i´m sure they´re far off 4/4,5 volts.....

    ReplyDelete
  23. Thanks Heiko! Any modifications? And what is your power supply ?

    ReplyDelete
    Replies
    1. Only "mod" is a 250K presence pot (less overall treble), stock wallwart (1000mA).

      Delete
    2. Thanks, how about your jfets? Matched with what readings? :)

      Delete
    3. Build another one the last night...the same problem again. Working on 18v. But on 9v its weak overdrive...

      Delete
    4. No, not matched and my readings won´t help you as you have others in your build ;-). Strange.... Your 100R really reads 100R....?

      Delete
    5. Here is a video using my 5th vero build...
      https://www.youtube.com/watch?v=RwNNb7tbvqU&feature=youtu.be
      Powered with 19v power supply from a laptop.
      Having a great problem running it on 9v.
      I hope for some guidance and help!!!

      Delete
  24. I had some time tonight and took another look at mine. i had replaced the jfets and it sounded like shit. I mounted some new SOT-23 j201's on some adapter boards and it sounds good now.

    For those of you having problems with not enough gain, what JFETs are you using and where are they from?



    I still have the issue with the last 10% of travel on the treble pot cuts the volume out compeltely. i tried replacing the pot but i get the same effect. not sure where to look. i checked the board and everything seems ok.

    Q3: i can't bias it to 4.5V with the trimmer. the lowest voltage i can get with it is around 5V. before my problem was with Q2 and Q3. makes me think that if you're going to build this with J201's that you should use 100k trimpots.

    ReplyDelete
    Replies
    1. Hopefully it is from some fake jFets.
      Still trying to learn how to measure them and to calculate the corresponding resistors!

      Delete
  25. Please share your experience! Don't be selfish!
    Peace!
    DImi
    :)

    ReplyDelete
  26. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. This was written after 18 days of reading the forum. And it is not a act of desperation! it is an appeal to the mans who are tired to explain every day the same thing the smallest ones... :)

      Delete
    2. Lastly, I've tested the boards and they sound "great" but from 19v power supply.

      If you know how to modify your current batch of jFets corresponding elements in the each stage, then you will get it working as it should.
      But, again this is not for beginners! :)

      Delete
    3. My build works fine at both 9 and 18V, so:
      A) there is a problem with your build or
      B) your jfets are dodgy...
      You could buy some more trannies from *different* sources, i would send you a bunch, too....

      Delete
    4. Dear Heiko, Thank you for being willing to help!!! Only through experience of trial and suffering can the soul be strengthened, ambition inspired, and success achieved
      Is it possible to upload audio demos of your build, using 9v and 18v.

      It seems you build it, following strictly the layout posted in this full with information blog.

      Big thanks to the author for his enormous work!

      Delete
    5. I've got my trannies from Ebay....Couldn't find any here in my country!

      Delete
    6. Sorry, i have no possibility to do recordings here..... Where are you from? And yes, i build it verbatim to the layout above. You could have a look into the forum (open discussions -> "Bargains") to source some cheap trannies!

      Delete
  27. Looking for real j201 and 2n5457. If someone is willing to help and sell a few please write me! :)

    The transistor I own are all fake....

    A friend of mine measured them.

    Here are 3 of "j201":

    iDss and Vp
    2.7mA / 2.09V

    1.88mA / 1.63V

    2.41mA / 1.92V

    All 10 that I have are like that.

    Dimi

    ReplyDelete
    Replies
    1. Measured from the guide :
      http://runoffgroove.com/fetzervalve.html
      Yeah its typo error. Its negative!

      Delete
  28. This comment has been removed by the author.

    ReplyDelete
  29. Replies
    1. This comment has been removed by the author.

      Delete
    2. Thanks! Any suggestions about the box wiring?
      Ive got some oscillation....

      Delete
  30. Finally my DIY Jfet Carvin Legacy Pedal is ready for boxing. What are your opinion?
    https://soundcloud.com/diminalbantov/carvin-legacy-diy-jfet-pream

    ReplyDelete
  31. Built my Leegazzy, easy to set 2n5457s to 4.5v..
    also built the charge pump to run at 18v,
    plug n play, sounds great.. and thanks again to the vero.
    here some photos: https://goo.gl/photos/rXo7EisJppZA95E7A

    ReplyDelete
  32. F**k this. Already spent something like 20 hours on this circuit. As with all bias-happy JFET circuits, i built two. One with sockets and trimmers and other without them. This method allows me to find the suitable set of FETs, bias them just right and then solder them to the other board with fixed bias resistors. I have old bag of good J201s, tons of newer way off-spec crap J201s, good 2N5457s, 5458s, J310s, J112s, MPF102s, BF244s and BF245s to name a few. No. This piece of s**t just won't bias correctly. With 4,5-5 volts at drains, it's barely unity and gain is next to none. Biasing by ear and some lucky sets takes it closer to the demos, but then there are issues with oscillation.

    Guess i'll have a few more rounds with this before giving up. Thought i'd share my failure though. Just in case some of you can't get it running properly - you are not alone.
    +m

    ReplyDelete