how to connect a bass with two outputs with different volumes to an amp?

Musicfreak1988 · #1 09-18-2009, 01:44 PM

Okay you electronics-guru's...

I'm doing the final specs on a custom bass with 2 magnetic pickups and a piezo in the bridge. The piezo needs an active circuit which is fine by me, but since I want to be able to run the magnetics in passive AND use the piezo simultaneously, routing both signals to one output would give some impandance problems, I was told. So, the bass is probably getting two mono outputs. One for the magnetics, one for the piezo.

Here comes my question/problem: my amp only has one input. I could send the passive signal to a pre and both signals to a mixer, but I'd really like to have only one box (which can match both signals in volume) in between the bass and the amp and I'd like that device to be as small, lightweight etc... as possible.

After a search I've stumbled upon small mixers, but mixers with two mono channels often have a bunch of other functions I don't need/want. After a while I came across the ART Macro Mix (http://www.artproaudio.com/products....0&cat=13&id=71) which seemed perfect to me 'cause it's small, has 2 jack inputs and a mono (!!) output, which is very nice for use with a bass guitar. To be sure it would serve my needs, I contacted them. Sad enough, they told me that the Macro Mix isn't made for use with instruments (I'm guessing the internal preamp isn't strong enough).

So, does anyone know about a device that would suit my needs or can maybe give me a different solution (as of now, the bass is still in the pre-building phase).

Thanks in advance!

Addison · #2 09-18-2009, 02:24 PM

A Radial Bassbone would more than likely be exactly what you need.

http://www.tonebone.com/tb-bassbone.htm

Addison · #3 09-18-2009, 02:41 PM

Actually, after rereading your post, it lookslike the Radial PZ-Pre would better fit what you're trying to do.

http://www.tonebone.com/tb-pzpre-features.htm

The PZ-Pre allows you to mix both input signals, while I think that the Bassbone only allows you to use one channel at a time.

newbold · #4 09-18-2009, 04:33 PM

EBS MicrobassII??

Steveaux · #5 09-18-2009, 05:23 PM

If you go with an onboard preamp for the piezo, and have room for the controls, a simple A-B-Y switch would work.

Musicfreak1988 · #6 09-19-2009, 11:56 AM

Thanks for the help all, but I'm really looking for a smaller device (and if possible, cheaper) device than those above.

Stevaux, thanks for the suggestion, but an ABY doesn't allow me to match the levels of the two outputs (active piezo and passive magnetics). A true-bypass ABY with seperate level controls for each input (which are powerful enough to match the passive to the active signal) would be the thing I need, I think.

ehque · #7 09-19-2009, 12:17 PM

What's the point of insisting on passive, then requiring a preamp to bump the signal up to match the active piezo? I was just wondering.

Anyway, you probably won't find something THAT cheap, but a standard Boss LS-2 or a Barge Concepts VB-jr would work.

Musicfreak1988 · #8 09-19-2009, 12:36 PM

The initial idea was that I'd like to be able to run the magnetics and the piezo at the same time, but I like a rather organic tone, so I want to keep the signal as passive as possible. I realize that needing to bump the passive signal makes it active, technically speaking, but then every signal is active, 'cause you need to turn the gain knob on your amp when switching between active and passive basses. The idea is to maintain as much as possible of the passive character of the tone of the magnetics, merged with the active signal of the piezo. Without a box in between, the piezo will be 'twice as loud' as the magnetics...

Musicfreak1988 · #9 09-20-2009, 07:05 AM

I just stumbled onto this: http://www.kksound.com/pdf/dualchannelpro.pdf... Would this work? I have no idea if 1 Mega Ohm inputs and 10 Kilo Ohm outputs are the standard or if they're usable with an active piezo and a passive magnetic signal...

SGD Lutherie · #10 09-20-2009, 01:20 PM

If you are going to run the passive pickup signal to a mixer or preamp, than a much better solution would be to have that mixer built into the bass. You need to buffer the passive pickups to mix them with the piezo preamp, so you are going to either do it after the bass, or you can do it right in the bass. Either way, you have to make the passive pickups "active" before mixing the two.

It's going to be the same situation.. there's no way to mix passive high Z signals with active low Z signals.

I'd prefer to do away without an extra gadget in the signal chain, and two patch cords, and mix them right in the bass, which is the usual way to do it.

Bassman203 · #11 09-20-2009, 01:24 PM

I would just use a y-cable splitter

SGD Lutherie · #12 09-20-2009, 01:26 PM

Quote:

Originally Posted by Musicfreak1988

Without a box in between, the piezo will be 'twice as loud' as the magnetics...

Besides that, the low Z output of the piezo buffer will load down the passive if you try to passively mix them. That will make the magnetics low output and dull sounding.

So you have to make them active somewhere. If you keep the input impedance lower on the magnetic's amp, they will sound more passive.

Passive pickups are not more organic sounding, they just have less highs and a lower resonant peak than when you buffer them. But that's easy to fix with some resistors and maybe a cap.

SGD Lutherie · #13 09-20-2009, 01:26 PM

Quote:

Originally Posted by Bassman203

I would just use a y-cable splitter

You can't because of loading... read my post above.

walterw · #14 09-20-2009, 02:31 PM

i know there are onboard guitar preamps (and so i assume bass preamps as well) that automatically mix magnetic and piezo sources onboard when a mono cable is plugged in, but spit the outputs into passive magnetic and active piezo when a stereo cable is inserted.

this would let you run the mags passive into one amp and the piezo active into another, or blend them both (active, the only way as has been pointed out) into one amp.

SGD Lutherie · #15 09-20-2009, 02:43 PM

Quote:

Originally Posted by walterw

i know there are onboard guitar preamps (and so i assume bass preamps as well) that automatically mix magnetic and piezo sources onboard when a mono cable is plugged in, but spit the outputs into passive magnetic and active piezo when a stereo cable is inserted.

this would let you run the mags passive into one amp and the piezo active into another, or blend them both (active, the only way as has been pointed out) into one amp.

That's a good suggestion. I think his initial idea was to not run the magnetic pickups into a preamp, and do it externally. But as I mentioned, that seems cumbersome for little to no added benefit.

SebbyNC · #16 09-20-2009, 03:00 PM

Yes, the GraphTech Acousti-Phonic preamp allows you to either have 2 separate channels if you plug a stereo jack, or a mixed magnetic-piezo sound. There's a trimpot on the mainboard to adjust the level of piezo with regards to magnetic output signal. Worth to check it out I think (starts à $70 with the basic kit).