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[教學] diy ZVEX Super Hard On

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kelvin_nike 發表於 2011-5-2 23:18:27 | 顯示全部樓層 |閱讀模式
本帖最後由 kelvin_nike 於 2011-5-3 00:02 編輯

Quick And Easy DIY SHO                                                Hey all -

I've heard of numerous attempts from folks building macguyverized SHO's with readily available parts (i.e. Rat Shack).

I just had to try it out myself:

1. To see if it really works
2. To see if it sounds really good

Lo and behold, both 1 and 2 are realities, and you even get the charming "crackle OK" effect as well.

Basically, you just sub a pair of 1 MEG resistors for 10 MEG units (either is adequately high enough to give a good, bright input impedance), a 22K resistor in place of the 5.1K, and a 20K/25K pot in place of the 5K unit.

Also, while the BS170 transistor is anything but unique, you won't find it at Rat Shack. But if your town has an electronics supplies store, it's probably available there. If not, you can usually find a 2N7000 at such stores. If Rat Shack is truly your only option, an IRF510 can be used, but with less gain (but the SHO has so much with the BS170 that it's not much of a factor, IMO). Just make sure you get the gate, source, and drain connected to the right spots, as not all mosfets are laid out in the same sequence.

Granted, to truly macgruberize this build, you need access to a DPDT stomp, but you could actually use a toggle instead. Since many folks leave the thing on all the time, you could even omit it - just make sure that the juice is cut when not in use, with either a dedicated power switch, or stereo jack for the input, to switch the battery off by pulling the input jack.

Then there's the enclosure. Obviously no Hammond boxes at RS. Not to worry - you could get one of their plastic boxes and shield the interior (awesome macguyverization possibilities there). I've also seen pedals built from junction boxes, PVC end caps, small baking pans flipped upside down, etc. Go hog wild, here.

How to build the circuit itself? I'll leave that up to those who are up to the challenge. It's not that challenging to build on a perfboard, in all honesty. Just two capacitors, two diodes, one transistor, four resistors, and one potentiometer is the whole circuit.

Anything else to modify? If you don't like the full spectrum bandpass effect of the SHO, you can cut down the input cap to .01uF-.047uF, and the output cap to .1uF. The stock value of 10uF for the output is overkill, IMO. YMMV.

And if you can build one of these, you can build a Super Duper, or even a Box of Rock. They both use the SHO in a modular fashion. The BOR is basically a BSIAB with mosfets in place of the jfets. I've also heard that the Box of Metal is also modular in fashion. If you're up to a slightly different challenge, you could build Joe Davisson's Obsidian. It's basically a variation of the BOR minus the boost stage and pot crackle. SHO_MAC.jpg
angus 發表於 2011-5-2 23:34:39 | 顯示全部樓層
應該係super hard on~
 樓主| kelvin_nike 發表於 2011-5-3 00:02:26 | 顯示全部樓層
唔可以比人知係一樣lol
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