I need a bigger bottom... end

[octafish]

I have been jamming with a couple of mates (guitar and drums) and we are thinking of getting a couple of gigs. With two guitars and a stripped back kit we are missing a bit of bottom. I need a temporary bass boost for a coupla songs.
Any circuits you can recommend?
Will the Rocktave or Shocktave handle power chords politely?
Any other tricks you can recomend? I could probably borrow a bass amp would that help?
I could tune my acoustic right down (I saw Bob Log III a while back he was tuned down to the ground sounded kinda cool). Didn't really be swapping guitars too much cos I would like to switch it in/out in the middle of songs.  
I guess the question I am skirting round is: Does anyone know what effect Jack White uses to give his guitar a bass kick when he plays live? Is there a DIY work around?

[cd]

I can't remember the guy or the band (might have been "Local H") but the guitarist in that band had a similar problem.  He got a tech to swap out the E and A strings for really big bass strings, and installed a P-Bass pickup so it only sensed the two increased low strings.  With a stereo output jack, the two low strings went to a bass amp and the other four strings went to a guitar amp.

[cd]

OK, my faded memory was right, it is the band Local H.  See here:

http://www.themusicedge.com/cgi-bin/moxiebin/bm_tools.cgi?print=384;s=4_5;site=1

[octafish]

Yeah I got Pack up the Cats floating around somewhere. Seems a bit extreme though. I might start looking for a cheapo strat though. Also I saw this when looking for a schem for a Prescription Experience
http://www.slinkp.com/pw_toys/gass . Was looking for something a bit easier/modular though. Thanks.

[Steve C]

I realize this is a little much, but it might be something to think about.  I had this friend that would use a splitter to split the signal then to get the low end he'd run it into an octave down pedal, then into a crossover, and bass amp.  Just for some ideas, hope it helps.

[bwanasonic]

There are the two factors of generating a low fundamental and also of being able to amplify it properly. An octave divider might work if the amp you're using can handle and project those frequencies. My guess is it would involve a minimum of a two amp setup and an A/B/Y switch.  Not sure how much of a factor tuning of the drums is in this equation, but it's something to consider.

see also: The Cramps, Sleater-Kinney

Kerry M

[Mark Hammer]

Octave dividers of the usual analog variety are MONOphonic and only respond suitably to single notes.  If you try and play chords through them, they WILL misbehave.  That may well be what you're looking for, but if it isn't you are hereby warned.

Having said that, I pulled apart the old dbx subharmonic synthesizer I bought 3 years ago (and only plugged in for about 20 minutes since then) and was surprised to find that it too relied on the same 4013 flip-flop chip/approach to produce suboctaves.  

So how can such a unit be applied to a stereo multi-source signal, typical of what comes from a phono cartridge, tape deck or CD?  Without looking at a schematic, it would seem from the boards that dbx simply filtered the bejeezus out of the signal such that only the very very low material would be sent to the flip-flop divider.  Given that the very low end of any music source is much more likely to be single notes, the stuff that is polyphonic goes unprocessed, and the stuff that does get processed tends to be more to the octave-division process's liking.

If you think about it, this is almost the complete mirror opposite of "exciter" circuits.  At their heart, they ARE distortion units.  So how is it that you can run an acoustic guitar through what is ostensibly a fuzz an make it sound "more acoustic"?  By selective filtering.  If you clip fundamentals or lower order harmonics, it WILL sound like a fuzz, but if you clip just upper-mid harmonics and above, it just sounds like sibilance and "air".  Similarly, if you frequency-divide the entire audible spectrum, it will sound ugly, but if you just frequency-divide that which is *intended* to be low, it comes out as more robust low.

What this means is that IF you made or got your hands on an octave-divider, you would want to use it to effect and blend in only the low content with the normal signal.  That is: guitar goes to splitter, path A goes where guitar normally goes, path B goes through 18db/oct or steeper lowpassfilter set to 150hz or so, filter output goes to octaver, and octaver output gets blended in with already processed gutar signal at last possible juncture.  Tricky and complicated.

Another approach is something I've suggested a few times here and there, which is the realm of subwoofers.  Most guitar rigs seem almost explicitly designed to ignore content in the <150hz zone.  Some commercial companies (e.g., Rivera) have tinkered with the addition of subwoofers to make them more "7-string-friendly", but it hasn't spread like wildfire.  Consider getting yourself a 10" subwoofer in one of those MDF+carpetting enclosures you find in trucks and pickups, and feeding it with a 50W or so clean solid-state power amp off the line/headphone out of you main amplifier (passing through an appropriate LPF first).  The advantage of doing it this way, is the same advantage touted for bi-amped/tri-amped systems generally, and that is that big transients at the very low end will not interfere with functioning above that range, leaving everybody plenty of headroom.  The alternative - cranking up the bass end of the main amp with EQ-ing - generally doesn't deliver as much thump and also introduces distortion when large speaker excursions occur in response to low transients.

The added advantage here is that: a) you'll have a speaker deliberately designed to deliver ultra low-end and ignore top end (which means you get to keep whatever gutar sound you have and like now), b) bass "thrust" can be adjusted separately by simply setting the subwoofer-amp's level (which means no impact on your current EQ settings or tonestack), c) the subwoofer arrangement is inherently polyphonic so power chords are valid currency, d) you can easily go back to a "just guitar" sound and rig when you want to.

[octafish]

Thanks for the replies. At the moment I am cluydging something together with a passive a/b box line router to my amp and a bass amp. I am also using heavy strings and tuning down an octave ala Bob Log III. The guitar line uses a trebly booster with a BMP tone control plus all the other stuff tremolo/fuzz/etc. The bass line makes do with a AMZ mini booster and electra distortion (caps modded). I like the idea of the subwoofer setup. I could probably buy all the bits I needed from a car wreckers using a bridged amp to drive the subs. If we persist with this line up much more it might be worth considering. The drum kit has been further stripped back to just highhat, snare and kick, no toms. A lotta Sonics, Cramps, Mojo Nixon and Rev Horton Heat covers at the moment but we have written a few hotrod tunes of our own. Echo on all the mics, tremolo on guitars hootin' and hollerin' havin' fun!

[bwanasonic]

A lotta Sonics, Cramps, Mojo Nixon and Rev Horton Heat covers at the moment

All near and dear to my heart! I request a Gun Club tune.

Kerry M

[downweverything]

Ive done sound for local H quite a few times, what i remember was he just had a normal guitar and played mostly power chords ran through a splitter with one end to a guitar amp and the other through a boss octave pedal connected to an ampeg svt bass amp.

http://www.ottosdekalb.com/Assets/Photos/Local_H/P5.jpg

thats the back of my head at the monitor desk.

[StephenGiles]

Octafish, this is what you need:
http://www.rolls.com/data/rp221man.pdf
Stephen

[Greg Moss]

I believe jon spencer's soundguy used a cheap pa crossover at the front of house console to split the guitar signal into two board channels, and he'd tinker with the sound from there.  I believe spencer also used an octave as well.

Todd Rittman of US Maple uses modified guitars which send the neck pickup out one jack to a bass amp, and the bridge to a guitar amp.  He uses bass strings for the low two strings.  He uses a finger picking style that sounds like separate bass and guitar players.

The metal band Meshuggah has eliminated their bass player, and now the remaining string palyers use 8-string guitars.  I'm not sure what the amp setup is (I think a bunch of line six stuff, but I could be wrong).

For bass I used to use 2 channel amps which would allow selection between a/b or both.  I would split the signal before the amp, and run all the effects into channel A, and eq much of the low end out of it, I fed the clean signal into channel B, and took the highs out.  Besides keeping the lows clean, this setup allowed some interested tone variations on the fly - dubby rumbly bass (with the "highs" channel off) and fake guitar (the "lows" off).

Right now I'm in a bassless band, and I'm tuning the low string down to C, and using a .65 bass string.  Playing through a bass amp, and sounding pretty good so far......

Good luck, I'm curious to see if you come up with any good tricks I can steal!  

Greg