Some thoughts on tube emulation.

[Bill Mountain]

I have spent some time trying to capture the "tube" sound and my results have been less than stellar.  After some experiments with tube overdrives I have concluded that I don't like them because they are too harsh (I play a high output bass and run into all sorts of problems with the low end and such).   I have been looking at a couple of BJT fuzz and booster circuits that I had originally dismissed because they were too harsh sounding as well.  Then I had an epiphany (a new idea to me but might be old news to some of you) that in most great tube amp designs the preamp tubes actually clip quite harshly and it is the power tubes job to smooth that out when they overdrive.  So now I'm looking at some of my BJT circuits that while they may have sounded harsh they did at least sound organic.  My plan is to work up a nice BJT boost or fuzz and run that into a smoother power amp sym type of circuit.

This leads me to my question.  Where would you guys go next?  Jfet Muamp, Mosfet overdrive (maybe 2 x SHO's), or some sort of hi voltage power transistor!  The sky is the limit.  I'm just looking for some ideas I haven't tried.

Peace!

[Earthscum]

I'd try jfets and mosfets. Maybe try a CMOS OD or something... check out some of the stuff at http://www.runoffgroove.com/articles.html

Remember that if you come across a good drive, but you want more of the clean, it's usually easy to implement a clean blend knob. I keep finding, though, that most designs that already incorporate clean blend usually do it BEFORE the filter, and this drives me absolutely crazy. IF you want to put any filtering on the clean side, you'd want to have it independent of the distortion side, otherwise you only get a good mix under certain circumstances.  Pet peeve of mine, along with a single cap change and calling it a "Bass" version.

I did find a trick with Jfets and diodes... I'll hit at it tomorrow morning and see if I can make it work with J201's. It basically compresses a signal, at lower signal inputs it acts totally tube-like in how it mellows out higher velocity portions of the signal, and as the signal gets bigger... well, without actually scoping it, it sounded like a perfect dub when I hit it with a 5V square wave. It acts tube-like, BUT it won't distort. Basically, you put the distortion in front and let the circuit tame it.

It works with 2SK117GR's... I just have to throw it back on the board, make sure it works right, and convert it to work with a J201, and probably just make it work with any fet, I guess. lol. I'll try to get it posted up by tomorrow night at the latest.

[Bill Mountain]

That's quite generous of you.  I can't wait to hear about your results.  I actually just got some J201's in.  I've been using MPF102's and they seem to be quite limited in applications.

Today I'm gonna bread board an Electra into a SHO and see if this will take me in the right direction.  I plan to try experiment with diode placements.  I'm sure it's been done but I've never seen a mosfet with diodes in the feedback path so I'm interested to see if that works out well.  Sort of like a Muff stage with a mosfet.

Thanks!

[esdiezy28]

J201s are godsends. I mainly use my MPF102s as discrete buffers, though I heard you can use them in an Orange Squeezer Compressor to replace the 2N5457s. What is a SHO? Hope you achieve success. ToNy

[Bill Mountain]

J201s are godsends. I mainly use my MPF102s as discrete buffers, though I heard you can use them in an Orange Squeezer Compressor to replace the 2N5457s. What is a SHO? Hope you achieve success. ToNy

SHO is a Zvex "Super Hard On".  It's a mosfet boost.

[esdiezy28]

Thank you! I've seen that (SHO) mentioned in several threads and never had any idea what it meant. Always a good learning experience around here!