Being Mojo free. Is it a good thing???

[Bill Mountain]

I pride myself in being mojo free in my designs.  But sometimes I think I take this motto a little too far.  For example:

Do you guys consider Ge diodes as a mojo component?  What about JRC 4558's?  I'm working on a pedal that sounds great with Ge diodes and the 4558 but my no mojo credo has me putting TL072's and 4148's instead.  Both sound fine but I wonder if I'm doing myself a disservice by not even considering "mojo" components.  Does it sound better with the GE and the 4558?  Maybe or maybe not.  But to me it is almost not worth it so I can keep my motto.  Now I understand that certain "mojo" parts have particular characteristics that are desirable (like clipping thresholds in diodes) but you can almost always find a modern or cheaper part (schottky diodes instead of Ge) to use in it's place.

Why do I have parts I consider "mojo" parts if i don't use them?  We'll it's always worth trying but I have only once found a situation where the part really did matter.  That was when a NTE 938 (LM308 substitution) stomped all over a 741 in a simple dirt box.  But. with more filtering or in a live setting, I probably wouldn't have noticed.

This also expends to high end parts as well.  I tried some 833's and Burr Brown chips and while it sounded great (maybe too much lowend) it didn't seem worth it either.

Am I crazy???  Does anyone else feel this way?

[Pablo1234]

I don't consider thoughts like that. When I build something I look at specs and cost. Though experimentation to make your own mind up on a part is critical to developing your understanding on subjects. Mojo too me just signifies that the part has a spec that people are not aware of like diodes sound different due to their internal resistance and capacitance from one too another. Once you understand the spec you can simulate it with different parts and have more control over the outcome.

[Bill Mountain]

I don't consider thoughts like that. When I build something I look at specs and cost. Though experimentation to make your own mind up on a part is critical to developing your understanding on subjects. Mojo too me just signifies that the part has a spec that people are not aware of like diodes sound different due to their internal resistance and capacitance from one too another. Once you understand the spec you can simulate it with different parts and have more control over the outcome.

But why go through the trouble to simulate if the mojo part sounds fine to begin with?

This is the question I've been asking myself.  I take a hard stance against designing with obsolete parts because I want to know that I could always build another one in the future if I want to revisit a design but some parts are still wildly available decades after production.

[CurtisWCole]

I say that you're thoughts are spot on...as long as you're LED's are blue. 

Curtis

[Seljer]

I don't buy the mojo with opamps, my philosophy is that what matters here is noise/current use/headroom, the bandwidth of most opamps is waaaay past audio, whatever famous sound you get is from circuity around it (I'm going to link this awesome demonstration here: http://www.youtube.com/watch?v=bpTv2jAree8)

Diodes however do vary, germanium diodes to have a certain characteristic that makes them different for clipping from say regular 1n4148... but I don't believe that warrants digging up boxes of NOS germianium diodes from the 60s.

[fpaul]

I think for very few dollars you could stock enough ge diodes to cover future production.  A few dollars more would cover the 4558s.

Personally I would put a premium on what sounds good but I build pedals to use not sale. 

[Earthscum]

IMO, "mojo" parts are there for bragging rights. "Ge Fuzz" is not mojo, unless you start touting "features military spec NOS CVxxx transistors!" then becomes mojo.

4558 makes different sounds in certain circuits, nothing "mojo". If you have a choice between chips, and they sound the same and function the same, just use the more common chip and save the 4558 or whatever for where it can be better utilized.

Take the Rat, for example. If you build it with an LM308, there's nothing "mojo" about it. Just compare the 308 against any other chip and you'll see there's no mojo, just pure "Doing What it's Doing". Mojo is "metrosexual". Mojo is "Flambouyant Gay". Mojo is "Jersey Wannabe Tough Guy". Mojo is just image, not about the particular part. Don't NOT use a 4558 because of a fear that it may be "mojo". If it sounds good, use it. If it looks pretty, then consider the circumstances... does it sound good? lol.

BTW, Ge, Si, and Schottky diodes all have their individual characteristics. Schottky works great when you need the low Vf of the Ge, but you aren't worried about (or you desire) the sharper sonic qualities. Ge works wherever you want or need it to, low Vf and "fuzzier" clipping than Si. No mojo in it at all. As a matter of fact, I have some OA85 NOS diodes that sound totally different than any of the Ge's I've bought online. I've been using them in a "Zen" circuit with Schottky's and 2N5458 fets and 4558's. They are a bit too soft for my taste, but they add just a bit of fizz to the underlying tones and sound great with guitar. I tried 3 different Ge diodes, and these were the only ones that gave me a sound that I couldn't get just by swapping out a Ge/Schottky with a regular Si diode. So, in that particular circuit, I use a couple "mojo" items, but it's simply for the sound.

ETA: I'd have more space without the horse pill diode, but it just sounds good! Also, went through TL072, NE5532, LM358, and 4558. 4558 sounded the best. 5532 was too "bright", let way more distortion from the upper spectrum come through. TL072 sounded too "soft", and the 358 just sounded like the 5532, for the most part (if you A/B them, you can hear the difference, but it's not enough, IMHO, to nitpick on).

[Bill Mountain]

Just to add to my level of commitment to "No Mojo".  I use cheap ceramic caps for anything under .47uf.  Why?  Because I have a boat load of them!

[LucifersTrip]

...but I wonder if I'm doing myself a disservice by not even considering "mojo" components.

yes, of course you are. your main concern is that is sounds good...so use anything at your disposal to that end.

[R.G.]

In Texas, we have a saying: if it's true, it ain't braggin'.

If a part does what you want, and really, truly has some difference that's measurable and repeatable, just because other people li..., er - claim non-measurable and uniformly good, if non-specific benefits from it does not automatically make it wrong to use it.  If you're only putting it in because it makes good advertising copy and other people blather about it, that's li... er, attributing magical powers it doesn't have.

Mandrake/mandragora root does/did have medical uses quite beyond its use as a mojo hand. Using it for a love potion is nonsensical at best.

If it works, use it.

[digi2t]

Little known fact about mojo; Like honey, it lasts forever without preservatives.

I have a jar of mojo in my pantry. It's just right of the sky hook, behind the bucket of steam.

[CynicalMan]

Little known fact about mojo; Like honey, it lasts forever without preservatives.

I have a jar of mojo in my pantry. It's just right of the sky hook, behind the bucket of steam.

I buy it by the gallon:

[Earthscum]

I buy it by the gallon:

Damn! Find that on Ebay? How does the lot test? That's not blacktopped Mojo you bought, isi it?

[MoltenVoltage]

I'm just waiting for someone to start selling relic'd transistors that have been run hot then dunked in whiskey.

[darron]

the opamp would be a bit of mojo. but the GE diodes would be preference. it's measurable. the forward voltage is much less than regular silicon (so, more clipping, less volume) and a bit higher than a schotkky. clipping on a scope even behaves differently (so maybe even some frequencies are compressing differently too? important for a distortion).

i like this description for the opamps, they will all do "the same sort of thing". however, they are different functioning opamps for different situations. the tl072 has a FET buffer, so if you're building a true bypass TS (as oppose to a buffered bypass factory mod) then maybe it WILL effect the tone. then again, haven't tested.

i don't think using solid core cloth covered wire compared to stranded thin copper you ripped out of a gameboy will make a difference here though...

i did a write-up on my thoughts on this matter a while ago: http://www.dazatronyx.com/tech/quality/

[markeebee]

Mojo is "metrosexual".

Damn right. Old components often look nicer. More interesting. Cool shapes/colours/text.

Even to the uninitiated, mojotastic stuff is more visually pleasing than 'standard' plastic stuff, I reckon. Probably doesn't ever sound different enough to justify the extra few pennies but it just looks nicer.

That's me waving at you from the shallow end of the pool.

[digi2t]

Little known fact about mojo; Like honey, it lasts forever without preservatives.

I have a jar of mojo in my pantry. It's just right of the sky hook, behind the bucket of steam.

I buy it by the gallon:

+1 

[slacker]

The JRC4558 only has any mojo when used in a Tube Screamer, anywhere else it's just A. N. Other opamp. Deliberately not using it in a TS is just admitting that it has mojo, it's inverted mojo. Like inverted snobbery, inverted mojo is just as bad as mojo  

[frank_p]

The JRC4558 only has any mojo when used in a Tube Screamer.

Huh    The 4558 attracts chicks only in the tubesceamer ?

[Colonel Angus]

Just 2c here, but I just got my GE diodes and have comparing them to an asymmetrically clipped set of (2 3mm red LEDs and 1 1n4001) in my Kay Fuzz-Clone. The difference is audible and definitely a different character. More colors for the palette is a good thing.