black ice cube?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by mustangman, Aug 9, 2005.


  1. mustangman

    mustangman Member

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    ever herd of them: http://www.stewmac.com/shop/Electronics,_pickups/Components:_Black_Ice_overdrive.html

    it seems pretty cool. have any of you used one? well anyway my question is how would it be in the second tone pot on a strat, since the second tone pot doesnt work for most settings (with stock wiring) would that mean the OD from the back ice cube would only work on the pickup setings that use the second tone knob? or could i make it work?

    and another question which isnt really guitar but more effect related (dont want to bother people by making another post) if i got a true bypass, say fulltone switch, a output and input jack and a pot, the black ice cube, and some wire and some how wired them all togther. would that work? if so can anyone tell me how?

    thanks in advance.
     
  2. Soapbarstrat

    Soapbarstrat Senior Member

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    I totally lost interest in even experimenting with such a device, when someone on another forum said having one in your guitar will lower the pickup's output *all the time*.

    But, even before I heard that, I saw that so many said it does not sound that good, and needs to be used with pretty hot pickups. And, apparently it's pretty expensive for the few simple parts that it is.
     
  3. John Phillips

    John Phillips Member

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    Exactly. It's nothing more than a couple of diodes and possibly a cap. Total component cost about $1. It doesn't lower the output all the time, only when the tone control is down, but it still doesn't boost the signal at all or add gain or sustain, being totally passive.

    All it does is clip the signal at about .7V, which is roughly the output of a powerful single coil or a humbucker. It isn't 'overdrive' at all... it's a lo-fi fuzz-type tone, quite cool in its own right but not very versatile. The useful range is basically on or off too, so it's a bit of a waste of a rotary control.

    I did experiment with the idea, using various types of diodes - I found the best seemed to be a single old Germanium diode, it gave the most characterful tone and didn't cut the volume too much. That produces asymetrical clipping BTW - if you want symetrical, you need to wire two diodes in reverse parallel. If you want to smooth out the tone a bit, parallel the diode(s) with a small cap... I can't remember what the useful value range was, sorry.

    It would actually be better to put this sort of thing into a pedal IMO. The circuit you need is extremely simple - just two jacks which are connected to each other at all times, a single-pole on/off switch (not even a DPDT, let alone a Fulltone-type switch) which connects between the signal path on one side and the clipping components on the other, which are then connected to ground at the other end. You could build the whole lot for under $20 including the box.

    If you want to try it, start with a couple of 1N4148 diodes (a few cents each) and just connect them - one each way round - between the hot and ground terminals in a cord plug, that will tell you straight away if you think it's worth going further with.
     
  4. GuitslingerTim

    GuitslingerTim Member

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    I bought one--they suck.
     
  5. unclej54

    unclej54 Guest

    i've experimented with them a good bit and while they won't compete with a pedal they're pretty cool at high volume on a guitar with a high output humbucker..not much on a single coil. you can attach the diodes to the output jack and hook them up to a mini-toggle to turn them off.

    but i did make a small, cheap passive pedal that i sell in my shop to kids who can't afford pedals and just want a little different sound. and like john phillips i experimented with about 6 different diodes and found that the batt 41 was the best for me.
     
  6. John Phillips

    John Phillips Member

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    I've just been messing about with a few more combinations, and found that the range of tones you can get with different diodes is quite wide, though not necessarily all useful.

    Best for 'musical', conventional fuzz: pair of OA47s - current production type, not hard to get. Responsive to guitar tone and dynamics, not much top-end loss, and surprisingly little effect on apparent volume.

    Best for lo-fi, dying-wasp ;) tone: single ancient Mullard OA5, salvaged from some old radio or something I had. It sounds like something is broken :). Terrible (ie quite cool in its own way) top-end suck too... two of these back-to-back totally squash the output and almost make pickup selection irrelevant.

    I didn't have any BAT41s, but the forward voltage characteristic is about the same as the OA47 (on paper anyway, though that may not mean much in terms of tone).

    Surprisingly the 1N4148s (which I thought worked last time) give almost no clipping, so ignore the recommendation above! But not so surprising when you see the spec - over double the forward voltage of the OA47. It looks like around .4-.5V is the most useful.
     
  7. unclej54

    unclej54 Guest

    hey john..you might be able to answer a question for me..when i first started playing around with this i took four batt41's, tied two together plus to minus then took another two and did the same thing..then i tied the two sets of two together back to back and when i installed them there was no change from just using two back to back..i would have thought that they had a cumulative effect but evidently they didn't. got any idea why?
     
  8. John Phillips

    John Phillips Member

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    All they're doing is clipping off the signal at the forward voltage drop value, so if you have two (or any number) in parallel it does exactly the same as one - it doesn't reduce the clip point; the reason you have a pair in reverse parallel is to clip both sides of the waveform of course, but further additions don't do anything. The diode's resistance is essentially infinite until the forward voltage threshold is reached, so it won't really make any difference how many there are. I wouldn't have thought that any other characteristics of the diode response itself would affect the tone either, since they'll be acting exactly in unison.

    The only difference you might get is if the diode has a large parastic capacitance (like those old OA5s obviously do) - the more diodes you have, the softer the tone.
     
  9. Soapbarstrat

    Soapbarstrat Senior Member

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    I wish someone who bought one, would use a pair of end-nippers to try to break it apart in a way that would allow the parts inside to be seen (although they probably do the same like on my whirlwind A/B box, and sand all the printed info off the critical components)

    I also assume if I'm using single coils with around 8k resistance, I shouldn't even consider experimenting with this kind of passive device .

    ok, I remembered there was some info about the black Ice in the Stew-Mac 'trade secrets' :

    " This passive overdrive circuit is an easy to install 1/2" cube that replaces the capacitor on a tone control. It lets the guitarist dial in smooth variable distortion and singing sustain. "

    "Try the Black Ice ! There's no easier way to dial in some great "tweed amp" over-drive without batteries. Just be sure your pickups have at least 8K ohms of DC resisitance. "

    Maybe by "tweed amp" they mean an amp from the 50's that's in extreme need of a cap job and new tubes, sort of like John's experiment that sounds like something's wrong ? LOL !

    I actually kind of like the idea of a "something's wrong" effect. Put it in an out-board box and call it : 'F-up Box'
     
  10. John Phillips

    John Phillips Member

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    As you suspect, the single OA5 does sound pretty similar to a Tweed Champ... with a blown speaker ;).


    If they recommend a minimum of 8K they may be using silicon diodes, like the 1N4148s which clip at around 1V. The OA47s (and BAT41s) clip at .45V, which is enough to get an effect with a split Seymour Duncan '59 - only about 4K - although admittedly only just, and I am hitting the guitar pretty hard with 11s on ;)... they don't do much on smooth held-single-note stuff.

    Used as a pair, these diodes do sound quite 'normal', not 'broken' - but it's still nowhere near overdrive (Tweed or any other kind) or smooth distortion, it's definitely a very mild 60s-style fuzz, and does not add any sustain at all, since it's passive! So about 1 out of 10 for an accurate marketing description - and that's only because it is easy to install.

    What might be quite interesting is to build one of those 'F-up boxes' and run it after a clean boost pedal or an overdrive - I doubt you'd blow anything, since that's exactly the way some distortion pedals (eg the RAT, which uses 1N914s) work.

    I'm sure I saw a circuit for one once which used the diodes in series with the guitar signal too, which would produce a very odd output with massive crossover distortion - the ZVex Machine pedal may do something similar.
     
  11. unclej54

    unclej54 Guest

    doh...i should have known that. makes perfect sense when you see someone else write it down..i just couldn't get my brain around it when i was playing with them. thanks!

    soapbarstrat..if you cut one in half you'd find two diodes..nothing more. i don't know what value they are but that's all in the world that's in them. the good part about attaching them to the output jack is that your tone circuit is left untouched. and by the way, i've installed them on the tone pot as per stewmac and it didn't sound any different than on the output jack.

    the most fun i've had with them is installing them in an old beat up sg bass and plugging it into an old tnt-130 amp by peavy..now that's nasty sounding.:dude
     
  12. John Phillips

    John Phillips Member

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    Heehee... I have a friend with - amongst other not exactly modern 'hi fi' bass gear ;) - a '69 Gibson EB-1 (the Felix Pappalardi 'violin' one) and a '72 EB-3.

    I wonder if he'd be interested in this idea... :D
     
  13. unclej54

    unclej54 Guest

    i hadn't thought of this before but you could make up a little jumper with a couple of small aligator clips and the diodes in the middle then you should be able to unscrew the tip of a cord and clip the jumper to the pos and neg and hear what it will sound like without ever opening up the guitar..
     
  14. John Phillips

    John Phillips Member

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    That's basically how I've been testing them...

    Guitar > 4-way parallel splitter box > amp

    Then, using an old plug with screw connections to hold the diodes, just plug them into one of the unused jacks.

    I even have two of the old plugs, so I can directly A/B different combinations.

    :)
     
  15. unclej54

    unclej54 Guest

    well, now you're just showing off..:D
     
  16. Soapbarstrat

    Soapbarstrat Senior Member

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  17. John Phillips

    John Phillips Member

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    You'd have made the switch wiring simpler if you'd just gone top left > middle right > bottom left in the diagram :). No need for the sleeving.

    I must try some BAT41s...


    Given the color of the OA47s, I think I'll call mine "Vanilla Ice". ;)

    ...although it sounds a bit better than the name would imply :p.
     
  18. Soapbarstrat

    Soapbarstrat Senior Member

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    That's just a site I found. I'm much too lazy to actually do something like that, and make a webpage about it in such a short time.
     

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