DS-1..... almost where I want it..... info please

[5thumbs]

Thanks for sending the doc. to my email!!!! I was able to download it and open it up. VERY INTERSTING AND INFORMATIVE stuff you got there 5thumbs. After reading the entire document I converted my pedal back to stock and performed the MIJ MONDO mod (leaving the cliiping mods out because I don't have that type of transistor) and the pedal sounds pretty good.  I'm messing again with the high and low pass filters and getting some great results. I'm gonna be tweaking most of the night tonite and see what I end up liking. What other type of transistors can I substitute in the clipping section? I'm not to familiar with transistors so some different models would help. Thanks

You don't need a 2N3859A to do the clipping network in the Mondo-MIJ.  I've used scrap 2SC1815s before (same pinout as the 2N3859A), but really, all you need is a NPN silicon transistor.  2N3904/2N5088/2N5089/2SC2240/2SC945/2SC2458/NTE85/BC549/BC559/etc....all of these and more should work the same in this application.  Just look at the datasheet for the transistor so you can locate the Base and Emitter pins.  Remove the Collector and use the Base as the anode (+) and the Emitter as the cathode (-).  The only silicon transistors I can think of that you should avoid are some of the low-hfe silicon transistors like the 2N3440, as they clip at a much lower voltage than most other silicon transistors.

If you don't want to mess with the clipping network of the Mondo-MIJ, you could use the clippers I put in the VR-MIJ.  (I'm making the doc updates tonight and will send it to you when I'm done.)  I used a BS170 MOSFET with Gate and Drain soldered together, then put a 1N34A diode on the Source (with the line on the diode pointing toward the BS170.)  You use the 1N34A side as the anode (+) and the BS170 G+D as the cathode (-).  You then install it like you would other diodes in D4/D5.  It's a different sound than the Mondo-MIJ clipping network, but it's a lot easier to do.

I've not come across another clipping arrangement (yet) that sounds like the one in the Mondo-MIJ.  The VR-MIJ clipping arrangement sounds really good as well, but different.  (I can see why folks are going nuts over MOSFET clippers.  They're easy to do and sound quite good.)  The clipping network in the Mondo-MIJ sounds "heavier" when pushed hard, but the VR-MIJ sounds more "natural", almost tube-like (to use that overused term.)  You might bear that in mind as you pick your clippers.

[AC30Dirty]

hey 5thumbs, would a MPF102 transistor work well for the clipping section???

[5thumbs]

hey 5thumbs, would a MPF102 transistor work well for the clipping section???

The MPF102 is a n-channel JFET, not a bipolar transistor.  I've only tried NPN bipolar transistors, so I can't offer any advice on how an n-channel JFET would work in the Mondo-MIJ.  With the JFET, you'd tie the Gate and Source together, then use the Drain as the other end of the "diode".  I've never used a JFET as a clipper (yet), so I'm not sure about the polarity of the JFET "diode", but you should be able to figure that out pretty quickly with your DMM.

Another thing to consider is the clipping threshold of the MPF102.  The majority of Si NPN bipolars (Base->Emitter) I tested clipped between 650-700mV.  You might want to test the MPF102 configured as above to see what its clipping threshold is.  If it's different from the 650-700mV of the NPN bipolars, you might end up with a groovy sound, but different than I ended up with.  Let your ears be your guide there. 

[askwho69]

Hi Brett  i read alot of your build your own ds1 . . . i would to ask if you'd tried the lm358n as replacement of m5223al?