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DIY Stompboxes => Building your own stompbox => Topic started by: jonnyeye on April 22, 2015, 07:24:30 AM

Title: LM3046/3086 Superfuzz input stage...
Post by: jonnyeye on April 22, 2015, 07:24:30 AM
I've seen bandied about the idea of building a Superfuzz around the LM3046/LM3086, which makes some sense; having a nice matched pair of transistors for the octave up section, the gain spec on the transistors looks pretty good... until you get to Q5 and the restriction that the emitter must be tied to the most negative point in the circuit.  Sadly there is no use for such a transistor in the original Superfuzz circuit - you could just ignore it and use two extra transistors, but that seems wasteful to me, and the desire to get an entire Superfuzz out of one chip is too appealing! Here's one possible workaround - the input stage has been redesigned so the frequency response is really close, the input impedance is similar (at least above 500Hz where it matters more), clipping is likely different... probably close enough for rock and roll. R7 below is the Expander control. Untested at the moment.
(http://i573.photobucket.com/albums/ss171/jonnyeye/superfuzz%20input%20redesign.png~original)
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: antonis on April 22, 2015, 07:34:19 AM
You may call yourself a gang leader if you add a pair of diodes between Collector and Base... :icon_biggrin:
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: duck_arse on April 22, 2015, 08:24:17 AM
jonny - have a look at these threads, there's nuttin this geezer don't know about arrays.

http://www.diystompboxes.com/smfforum/index.php?topic=106531.0
http://www.diystompboxes.com/smfforum/index.php?topic=102477.0
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: digi2t on April 23, 2015, 12:11:08 PM
Quote from: duck_arse on April 22, 2015, 08:24:17 AM
jonny - have a look at these threads, there's nuttin this geezer don't know about arrays.

http://www.diystompboxes.com/smfforum/index.php?topic=106531.0
http://www.diystompboxes.com/smfforum/index.php?topic=102477.0

Well.... that has really made my day. Having the honorary title of "Geezer" bestowed upon me, by the ubiquitous duck_arse no less.

Oh happy man!!  :icon_biggrin:
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: duck_arse on April 23, 2015, 12:14:57 PM
steady, digi, that's a small 'g' geezer ....
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: digi2t on April 23, 2015, 02:12:51 PM
Small is better than none.

twss

;D
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: bool on April 24, 2015, 06:58:07 AM
Quote from: digi2t on April 23, 2015, 02:12:51 PM
Small is better than none.
...

(http://i.kinja-img.com/gawker-media/image/upload/s--qECMa-KQ--/c_fit,fl_progressive,w_636/txx8h3d5tag179bcp1pf.jpg)
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: duck_arse on April 24, 2015, 10:41:27 AM
bool - don't forget commando anna/anya's long arms ....

digi - pardon my ignorance, but twss?
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: digi2t on April 24, 2015, 04:18:28 PM
Quote from: duck_arse on April 24, 2015, 10:41:27 AM
digi - pardon my ignorance, but twss?

that's what she said
Title: Re: LM3046/3086 Superfuzz input stage...
Post by: duck_arse on April 25, 2015, 10:50:20 AM
Quote from: digi2t on April 24, 2015, 04:18:28 PM
Quote from: duck_arse on April 24, 2015, 10:41:27 AM
digi - pardon my ignorance, but twss?

that's what she said

okay, okay, she was igerant too, but what does it mean, digi?