Bass Guitar Level

[grapefruit]

I'm trying to figure out what the maximum peak-peak signal out of a guitar and bass guitar would be. By that I mean the max level out of a high output bass or guitar. I'm trying to determine wether I'll need more than 9V to avoid distortion. Does anyone have a clue or could point me to where I can find out?

Regards,
Stew.

[DDD]

9-Volt battery seems not to be enough to process bass attack decently. Thus there are many bass preamps that require 18 Volts.

[jonathan perez]

really?

[grapefruit]

That's what I thought. I might try either a boost regulator or inverting regulator so I have about 18V overall, and it can be powered from a 9V supply. I was trying to do it with rail-rail op amps from 9V but I'm yet to find an op amp that goes near the rails when used as a non inverting buffer.

Still, does anyone know what the actual peak voltage is?

Cheers,
Stew.

[MartyMart]

Passive single coil pups from 100Mv up, humbuckers nearer 1v and active pups as much a 2.5v !
I think a passive bass pup is around 800Mv, so should be fine with a well setup 9v circuit.
I did some recording with an active Music man bass and it totally overloaded the Sansamp Bass Di !
Just had waaaay too much output, hence the 18v for more headroom argument.
My own Precision bass is fine with the Sansamp and my 9v powered Flipster.

MM.

[Meanderthal]

 OMG, believe me, a 9v device is quite capable of clean throughput for bass. 

It's headroom that gets increased generally with higher voltages, but, really, how mych dynamic range do ya really need on bass? Unlike a guitar, because of the thick strings and all, it'll never exactly be as expressive as a violin or something, it's a BASS.

Are you using active and overloading yer inputs with too much signal? Some active basses are just way too hot... overkill.

Sorry, I don't have a number for ya.  But I can tell ya this- through long experience and some rather expensive trial and error, I now refuse to use an active bass. I can do that with a pedal if I want.   I used my ears to reach this conclusion, not math or some measuring device.

Attenuator?(as in Mr. Clean)

[alextheian-alex]

Depends on the bass, the strings, the player... etc.  If you run a hot active bass into a scope, you can see peak levels exceeding 7-8v. You can use a 9v supply if you are careful about the design,but if you want to be sure, you have to shoot high with the headroom, especially if you are adding any gain... otherwise you will be hitting the rail on peaks.  If you are using opamps, remember that not all of them will swing up to the rails, so if you have a 9v supply, and you lose a couple volts to the opamp, then you have only 7 volts of headroom, so you will clip on peaks with a hot bass.

A few precautions would be to pad the input level a bit, and use a rail to rail opamp.

it is a real problem if you are trying to rig up an active box to record DI bass... last one i did, i just ran it off phanton power since that is a free 48v supply.  but i was just in the studio, and was clipping a Radial j48 active DI... WITH the pad on... with my bass and guitar running EMG's and that box has more headroom than most DI's out there.  i also had to mod all my EMG's for an 18v supply because i was clipping the internal preamp.