Is there a 3-way switch for: passive mag or piezo w/pre or both..into one jack ?

jibreel · #1 10-20-2009, 09:14 AM

Greetings,

I am installing a Villex passive magnetic pickup in my Carvin AC-50 which already has piezo with the Carvin pre. I do not want to install a new pre which could blend them.

So... is there a 3-way switch that I could install that would let me choose from mag pickup only or piezo pickup only or both? And could this send the signal to one jack?

Any wiring diagrams?

Thanks

ebassotti · #2 10-20-2009, 09:35 AM

Have you considered replacing the mono jack with a stereo one, with the piezo preamp output on the tip, the magnetic pickup on the ring, and shared ground on the sleeve? That would give you flexibility for external blending or even stereo/bi-amping, and would be fully reversible in case it should turn out you don't want it after all.

Just a thought.

jibreel · #3 10-20-2009, 10:45 AM

Thanks for the idea.

Since I will have seperate volume and tone controls for both the mag and the piezo on the bass, it would be nice to have the three switch option for easier control. But I am open to all suggestions !

**line6man** · #4 10-20-2009, 01:10 PM

Are both pickups (piezo and magnetic) feeding the preamp?
It wouldn't be a good idea to use one with the preamp and one passive, as you would be combining high and low impedances.

fullrangebass · #5 10-20-2009, 01:58 PM

IIRC there are DI boxes that allow for 2 basses to be plugged in. I am not aware if they allow a mix between the two, but for sure they will be able to offer a choice of the two signals offered by the bass

walterw · #6 10-20-2009, 07:11 PM

you can not mix a passive magnetic with a passive piezo, they're like oil and water electronically (one's an inductor, one's a capacitor). you also will have little luck trying to mix a passive mag with an active anything; all you'd hear would be the active part.

either the magnetic gets its own path down a stereo cable to its own amp, or it gets preamped and then mixed with an also-preamped piezo. for combining, those are your choices.

jibreel · #7 10-20-2009, 08:26 PM

Thanks all. Looks like I will just run the mag pup and the piezo into seperate channels on my amp.

walterw · #8 10-20-2009, 08:57 PM

Quote:

Originally Posted by jibreel

Thanks all. Looks like I will just run the mag pup and the piezo into seperate channels on my amp.

actual separate amp channels with separate volumes, or multiple inputs into the same channel? because the latter wouldn't work either.

HogieWan · #9 10-20-2009, 09:10 PM

just put a simple impedance matching buffer on the passive output and then blend. It's the same type of circuit you get at the front of a stompbox or the front of an amp.

jibreel · #10 10-20-2009, 09:37 PM

Quote:

Originally Posted by walterw

actual separate amp channels with separate volumes, or multiple inputs into the same channel? because the latter wouldn't work either.

My main Acoustic Image amp has two seperate channels. So I would just run the signals seperately into the two channels. I will have on board volume and tone controls for each pickup. The original Carvin V/T/T premap for the piezo pickup and the Villex will have Volume and his mid-control along with his passive rotary tone booster.

HogieWan · #11 10-22-2009, 07:33 AM

Another option might be tape-wound strings. They are rounds with the nylon wrapping. They sound very much like rounds through magnetic pickups (obviously not the same, but close, even with a pick), but they are very thumpy over a piezo because of the softer material touching the bridge. This may give you a good mix of tones. LaBella tapes can be had relatively cheap at carvin.com

jibreel · #12 10-24-2009, 04:52 AM

Found a DPDT stereo jack. I had forgotten abou the battery needing to be turned on for the piezo preamp.

Then I will just use a stereo cable and a stereo to mono Y-adapter and use my two channel Acoustic Image.

Thanks all

http://www.guitarelectronics.com/pro...DT_Switch.html

bassbenj · #13 10-24-2009, 10:51 PM

Quote:

Originally Posted by jibreel

Found a DPDT stereo jack. I had forgotten abou the battery needing to be turned on for the piezo preamp.

Then I will just use a stereo cable and a stereo to mono Y-adapter and use my two channel Acoustic Image.

Thanks all

http://www.guitarelectronics.com/pro...DT_Switch.html

I'd like to add a magnetic pickup to my AC50 as well. It's the ONE thing that bass really needs. Mixing the two is a nightmare. I have a guitar with magnetic and piezo pickups and I did the stereo jack thing. I use a stereo cable and I built a small box that takes a stereo cable in and has two mono jacks out. You just put two ordinary guitar cords into those and run to two inputs (or two amps...which can sound amazing!).

Another thing to try would be a passive mixer. Just insert a 20k or so resistor in series with each output (piezo and magnetic) and then tie the two far ends together as the output point to the amp. This will reduce the overall signal level but should mix without a problem. A series switch that selectively turns off (opens up) each output can add control. So long as you can live with the reduced signal this may work.

I'd like to know what you do because I want to mod my AC 50 with a magnetic pup too!

zorf · #14 10-27-2009, 11:35 AM

you can not mix a passive magnetic with a passive piezo, they're like oil and water electronically (one's an inductor, one's a capacitor). you also will have little luck trying to mix a passive mag with an active anything; all you'd hear would be the active part.

I respectfully disagree.

I like just blending two together to a simple mono out.

One blend pot and one volume.

The mag is alway much hotter, but you learn where the taper is on the pot.

For me, simpler is better.

bassbenj · #15 10-28-2009, 01:10 AM

Quote:

Originally Posted by zorf

you can not mix a passive magnetic with a passive piezo, they're like oil and water electronically (one's an inductor, one's a capacitor). you also will have little luck trying to mix a passive mag with an active anything; all you'd hear would be the active part.

I respectfully disagree.

I like just blending two together to a simple mono out.

One blend pot and one volume.

The mag is alway much hotter, but you learn where the taper is on the pot.

For me, simpler is better.

As Einstein said: "Things should be as simple as possible, but not simpler!"

You are correct that one can hear the piezo fine, but it does not work well on bass. I have a simple passive magnetic-piezo setup I built for a resonator guitar and it's fine. A 1 meg pot mixes in the Piezo.

But here's the Oil and Water story. A piezo is a VERY high impedance device. If you feed it into a low impedance (low here meaning 100k like a typical amp input) it loses all it's low frequency output. On a guitar that doesn't much matter. On a bass it's critical. Hence bass piezos usually have some kind of active preamp with a very high impedance input (1 meg is minimum and 10 meg is better) where you use the OUTPUT from that preamp to mix with the magnetic pickup output.

In the case of a Carvin AC 50 the piezo pre is already there. I'm guessing that a 25k resistor in series with each output and tie together at the amp would mix them fine.

Justyn · #16 11-06-2009, 11:28 AM

Not to hijack the thread, but my bass has a passive pickup mated to a buffered piezo with a vol-vol-tone setup and I get a sharp dip in volume when I start to back off the magnetic volume. It (the volume) comes back, but could this be caused by the dreaded oil/water combo of un-preamped magnetic and buffered piezo setup?

Thanks,
J.