Active bass impedance converter?

[matta]

Has anyone attempted an active bass impedance converter?

Obviously the impedance from and ACTIVE bass is great for many a thing... running them into a fuzz pedal is not one of them and seems to overload the input stage of a pedal expecting to be seeing a high impedance source ala a 1Meg Passive Pickup... any ideas on simple, effect solution to convert an active bass signal to be more pedal friendly?

Cheers

Matt

 

[JohnRoberts]

You can always use a simple resistive pad to scrape off too much level, and you could select the values to raise the source impedance to be whatever you want, while I see less benefit from that.

JR

 

[matta]

Thanks John, I thought of that but the PAD seems to really suck the tone out of things... wondering if a FET wouldn't be a better choice? Also some pedals CAN handle the level, but the source impedance smears the tone, or maybe I'm just being overly critical of the PAD.

Cheers

Matt

 

[Gus]

The fuzz face fuzz type circuit has a summing input so the source z feeding it is a part of setting the first gain stage gain this also causes a EQ.

Think of it like a inverting opamp setup the bass mess is the input R

100K 47K etc / the input R along with the limited gain of the first transistor stage(why you select that transistor)

A active bass circuit often has a low output R and the coolness of the bass mess (pickups caps pots) interaction is taken away with an FF type circuit.

It can be as simple as a fet opamp stage with a 1meg or so input setup as a buffer and the you can look at NS app notes and make a 2 or 3 band EQ etc after it.

 

[recnsci]

[quote author="Gus"]The fuzz face fuzz type circuit has a summing input so the source z feeding it is a part of setting the first gain stage gain this also causes a EQ.
[/quote]

Yup. Take cheapest guitar pickup you can find and
put it in series with fussfase type circuit, that should do it.

Passive attenuators come with either noise penalty, tone penalty or
both.

Keep in mind two things: even passive pickup bass guitars have "hotter"
outputs than guitars (volt or two when hard strummed), so you should
take that into equation. Also, IMHO fuzzing bass guitar sounds much nicer
if you put 12dB/oct HPF in front of distrotion unit (cutoff at 'round 200Hz).

cheerz
urosh

 

[12afael]

mmm you don`t want something like a tech 21 bass driver? you can by pass the voicing/overdrive part.

I did a pcb for that project some time ago it should still be here in the forum. if not, let me know.

cheers
Rafael

 

[clintrubber]

[quote author="recnsci"]Keep in mind two things: even passive pickup bass guitars have "hotter"
outputs than guitars (volt or two when hard strummed),[/quote]
We had some talk about this before on these pages... 2V is a conservative estimation I'd say. IIRC 10Vpp on a good day :wink:

Also, IMHO fuzzing bass guitar sounds much nicer
if you put 12dB/oct HPF in front of distrotion unit (cutoff at 'round 200Hz).

Maybe an active bass would need this filtering even more, as these can have that hi-fi crispness that you could not use then, especially then.

Bye,

Peter

 

[tv]

try inserting a 100k trimpot between input jack (hot) and the input of your fuzzface circuit (the cap) - wired as a rheostat, not potentiometer (!) possibly you will have to replace the input electrolytic with a smaller capacitor. ymmv.

maybe: better find something like this http://www.ratdistortion.com/juggernaut.htm ??

 

[AMZ-FX]

[quote author="matta"]Has anyone attempted an active bass impedance converter?

Obviously the impedance from and ACTIVE bass is great for many a thing... running them into a fuzz pedal is not one of them and seems to overload the input stage of a pedal expecting to be seeing a high impedance source ala a 1Meg Passive Pickup... any ideas on simple, effect solution to convert an active bass signal to be more pedal friendly?
[/quote]

I wrote about something similar to this:

http://www.muzique.com/lab/pickups.htm

It has previously been used on bass by some builders, though I'm not sure if it is what you need. You might start out with a more simple pad like this:

The capacitor will preserve some of the highs and you may need to tweak its value.

regards, Jack