Friday 14 June 2019

Shin Ei / Univox SQ-150 Square Wave





12 comments:

  1. Hello,
    It seems that the image doesn't pop up for a bigger display?
    Did you build it? Does it sound good?

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    Replies
    1. Hi there.
      Image link is now fixed.

      And yes, I built it. If you are into filthy and nasy fuzzes it sure sounds good. Just avoid the ge clippers....silicon is the way to go.

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    2. Hi,
      Thank you Fuzzhead!

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  2. What am I missing... I only see three links

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  3. Well, I built it with the three links I see, and it sounds pretty great!

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    Replies
    1. Thanks for pointing out the typo, it is 3 links indeed.
      Glad you are liking it!:-)

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    2. I think i've read it's fuzz face based ?
      Does it play nicely with bass?
      Is there any impedance issue in the fx chain ?

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    3. Yeah it is fuzz face based with some interesting quircks. A J FET for Q2, output cap blend (Distortion ctrl) and hard clippers.
      I don't find it terribly bassy so for bass some mods might be necessary, like increasing the value of the 100nF input cap. I haven't noticed any impedance issues yet since I haven't stacked with other circuits...

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    4. Thank you, Fuzzhead. I think i'm going to try it at some point (i'm in love with the basic audio artworks, which made me know this stompbox!).

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  4. I'm building it right now (with some mods) :)
    How is the 20k trimmer supposed to be set? With voltge biasing from the transistor, or by ear (or both) ?

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    Replies
    1. Stock, it has a 10k resistor but I replaced it with a 20k trimmer to be able to to experiment with other J FETs. I don't have any recommended votages but it is easy to dial in by ear.

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  5. Hi,
    I just built it, and I can confirm that the layout is verified :)
    With the diodes removed, it sounds great as a warm and loud overdrive.
    I used a J201 for the Jfet, and the 10k stock value seemed the best (I used a trimmer, but it sounded best at half rotation).

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