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Guitars; Passive Or Active?


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I know this one's been chewed over 'till there's nothing left but gristle, but I need convincing. I've been playing bass for years, but finally got my own electric guitar and my 'knee jerk' response is to pop in a preamp. Bass players are much more likely to have active circuitry in their axes than guitar players. If you think about it, basses need all the frequencies they can get, especially if you play using slapping and harmonics and shenanigans. A preamp makes good sense in a bass, I put one in one of my early handbuilds during the mid 70's. That axe sounded so good, a fan followed my band around for three years offering me more and more for it each time I saw him. Yes, I did finally relent. Asked him only the price of materials, cuz I'm so nice.

Now here I am with my new guitar. It's a modified strat (grizzly kit) with vintage sounding low impedance (5.5k ish) alnico 5 mag pickups. I recently moved the middle pickup over by the bridge (slantbucker) and rewired it to get 13 combinations, 9 of which involve all three pickups. It really sounds great. So, why put a preamp in it if I'm happy, right? There's more.

As primarily a bass and keyboard player, I don't have a real guitar amp. I was thinking to kill two birds with one stone and install some sort of overdrive or tube distortion circuit into the guitar that would also serve as a buffer. That way, I could play through one of my clean amps and get all the grit I want right in the guitar. I know, I know. That's what pedals are for. But, it seems to me that, with electric guitars, some sort of overdrive is an almost universal need. I could borrow some pedals from one of my shreddy friends to audition the sounds first. One even has one of those 'legendary' older 808 tube screamers that there are circuit boards available for. Is this a ridiculous idea?

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dugg - we should chat. I have been tempted myself to add a circuit right to the guitar but have this fear (knowing electronics) that if the bypass fails I'm in constant shred mode (some may like that). Theoretically - it's a logical idea, in reality I'm very curious. I'm actually looking at a bass right now that I'm thinking of testing this on. Why? Seems that in a world of so-so amps and house PA systems, that would be a way to ensure the appropriate growl that we all play bass for. :D Just a thought

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prostheta, thanks for the warning. I was planning to install a preamp in the usual way, which would be zero gain, so that switching it in and out will not cause a volume change. That would be especially important if I used a distortion circuit. Don't want to have to readjust volume after switching it in.

As I undertstand it the main function of a preamp is to buffer the guitar circuitry against the instrument cord which is an unbalanced line. An unbalanced line has much more metal on one side than the other because the negative side is a big shield. More metal means that side has more capacitance, which adds to the cap you already have on your tone control and cuts more highs (and some lows to my ear) than you want. Put a really long cord on a passive guitar and you not only lose highs, but you start to get a sort of flabby sound. I keep saying guitar, but my experiences 'till now have been only with electric basses. It seems to me that the issue of preamps in basses has been pretty well established in the years since I first put one in mine, but I don't see the same enthusiasm in the guitar camp. I'm thinking there's more to it than I know now? GFS has some tempting looking stomp box circuits that are adapted for onboard installation. They even have one that copies that 'tube screamer' one everyone uses.

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prostheta, thanks for the warning. I was planning to install a preamp in the usual way, which would be zero gain, so that switching it in and out will not cause a volume change. That would be especially important if I used a distortion circuit. Don't want to have to readjust volume after switching it in.

As I undertstand it the main function of a preamp is to buffer the guitar circuitry against the instrument cord which is an unbalanced line. An unbalanced line has much more metal on one side than the other because the negative side is a big shield. More metal means that side has more capacitance, which adds to the cap you already have on your tone control and cuts more highs (and some lows to my ear) than you want. Put a really long cord on a passive guitar and you not only lose highs, but you start to get a sort of flabby sound. I keep saying guitar, but my experiences 'till now have been only with electric basses. It seems to me that the issue of preamps in basses has been pretty well established in the years since I first put one in mine, but I don't see the same enthusiasm in the guitar camp. I'm thinking there's more to it than I know now? GFS has some tempting looking stomp box circuits that are adapted for onboard installation. They even have one that copies that 'tube screamer' one everyone uses.

Pretty much the case, yeah! Basses benefit from preamps on the basis (no joke intended) that they benefit from the added oomph to handle high low (?!) frequency transients they produce in comparison to instruments in the guitar spectrum. A simple unity gain (gain of one....zero is silent!) preamp buffer sorts out cable capacitance issues, although cables seem to lose higher frequencies than the lower ones. Weirds.

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Thanks again Prostheta. I'm thinking I'm going to dive in and preamp my modded strat. I can easily wire a bypass switch so I don't offend the purists. Only thing I haven't decided is whether to build my own circuit or buy a premade one. I've built other boards before, so it's not a matter of a hurdle to jump. My main consideration for building my own would be to get a circuit that would otherwise be unavailable, like one of those legendary ampeg octave, ring distorto-whatever it was that they only made a thousand of.... I s'pose this is veering off topic, but does anyone have any suggestions on their favorite distortion stomp?

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