Low impedance Ceramic singles + Bartolini TC3?

[Triad]

Hello guys... hope you all had a very good end of the world... uh... end of the year.
I'm actually working on a few new ideas. I've made two low impedance singles with ceramic magnets, using pretty thin wire and winding them with 50% of the usual number of turns. I plan to use them with a bartolini TC3 booster, wired after the usual volume/tone controls with 500k pots. I also plan to put a couple of piezo sensors into the body with an on/off switch (but this one will not be affected by pots, put directly on the output).
I was wondering if there are other/better options to make low Z pickups usable with standard amps. I've read a few articles about mic transformers used for this purpose but I really don't know anything about that stuff... I'd like something that will work with basically every configuration (1 hb, 2 hb, 2 singles) even if they don't have the same output... so I can stock a few and have them available. The Barts TC3 is cheap and pretty easy to wire but I have no idea of how it works with the different impedance of low Z and/or piezo... is anybody here willing to enlight me?

[David Schwab]

The TC3 will work. I've used a TC1 I've had since 1976.

But what I usually use is a JFET preamp based on the Alembic Stratoblaster.

You will need a separate input for the piezos.

[Triad]

Hello David, thanx. Why do you think I'll need a separate input for the piezo? I know piezos are highest impedance systems so... do you think I'd have to run them thru a different booster or thru a buffer? This would make things pretty complicated. I don't need to get the full spectrum out of the piezo, though, but I like the fact it makes the body "drumming" amplified and the crispy hi-mids articulation it adds to the sound of a magnetic. Well, at least to the sound of a high impedance magnetic. Maybe the low z singles won't need the extra sparkle.

[David Schwab]

The piezos absolutely have to be run through a buffer. Otherwise you will get a thin scratchy tone. And you can't just mix them with the low Z pickups. The piezo will overpower the magnetic pickups, and it will sound like crap.

Probably the easiest way is to get one of those piezo/magnetic pickup preamps that mix the two together. Bartolini makes one of those. You may still have to boost the level on the low Z pickups however.

What I was doing was making a seperate buffer for each pickup, and then running the outputs to separate volumes, and summing those together. You could do something like that with the piezo too.

You are making a complicated setup, so that's what it's going to be.

[Triad]

You're right, LOL! Anyway I must say that piezo mixed with high impedance pickups sounds OK. Not soloed, of course, but mixed. I've seen the Bartolini buffer but never used one. I got used to make 90% of the instrument by myself and having to rely on third parts stuff makes me a bit nervous...
But the only way to get that kind of tone out of a high Z pickup is making the pickups with multiple coils, one for each string. That way more wire gets close to the magnet, the sound is clearer and putting everything in series gives a sort of Low Z tone without the low output. Not just the same thing but close. Shame this stuff takes a lot of time and work. So the choice is between relying on third parts products and putting much more work into the pickups. I knew it!

[Mike Sulzer]

winding them with 50% of the usual number of turns.

That really is not all that low an impedance; a mic. preamp would not be good. A transformer only accomplishes anything useful if you put it at the amp end of the cable rather than at the instrument, and the transformer you would need would be non-srtandard

[Triad]

Well, I guess I should have kept the number of turns around 2k for a real low-impedance but since I'm using ceramic magnets I was a bit scared that the sound could be too harsh and brittle... looks like I'll have to experiment with the TC3 after all but still have to find a solution for the piezo stuff. Maybe they'll be pretty balanced, after all. The pickups are huge so the measured resistance isn't low at all, even with the 50% of wire on the coils.

[David King]

Bartolini's MP1 should work here if you can find one. It's specifically for combining magnetic and piezo inputs. Other folks make them, John East in the UK has a nice one and Noll in Germany does as well. In the States all the usual suspects, Fishman, EMG, Barcus Barry, Highlander, RMC, Graphtech and so forth make versions that ought to work for you.
If you want to roll your own there's an open source schematic that was developed years ago by the folks on the MIMF forum.

[Triad]

Thank you, David. Yes, I've seen those schematics but mixing it with the Bartolini TC3 could be messy... and I'd avoid having two outputs. Could be nice for studio works but not for everyday's use.

[David Schwab]

Well, I guess I should have kept the number of turns around 2k for a real low-impedance but since I'm using ceramic magnets I was a bit scared that the sound could be too harsh and brittle... looks like I'll have to experiment with the TC3 after all but still have to find a solution for the piezo stuff. Maybe they'll be pretty balanced, after all. The pickups are huge so the measured resistance isn't low at all, even with the 50% of wire on the coils.

Is this for a guitar or bass? I was making bass pickups wound around 2k with ceramic magnets and steel blades. They sounded very nice, and not brittle at all.

Here's the Bartolini piezo/magnetic preamp:

Bartolini MPB2-918 Piezo-Magnetic Buffer Preamp

It will work with other preamps.

[Triad]

It's a big bass, extended range. I usually prefer to have less instead of more stuff into the electronics routing... so my basses are usually passive and I'm very happy with the sound achieved with the pickups. But there's always room for improvement, right? I thought I should have given a shot to the low Z stuff. I have a semi-hollow (passive) with an AlNiCo5 humbucker (around 15k?) wired to a couple of piezo sensors into the body with an on/off switch... I must admit I like what the piezo adds, even if it's not buffered. It makes you hear everything going on in the instrument acoustically, tapping on the body, strings noise etc. and is nice. Don't know how it would work with the medium Z singles, though... I guess it could be louder? I saw the Bartolini buffer but... still don't know how I'll like these pickups and I certainly prefer to have less parts to buy for a bass... shipping costs and troubles, delays etc. always made me mad.
I could probably leave the piezo unbuffered and connect it directly to the output jack with the on/off switch. In this way it shouldn't be too loud. I'll have to try, looks like it's the only way to find out how it will work in real life. An unbuffered piezo sounds like a bad idea but it's not bad for adding a bit of acoustic sound, high mids and spark to the tone. Of course I'd never do that if it was a piezo-only bass, it would lack lows and would sound ultra-harsh... I tried once.

[David Schwab]

Technically there's no such thing as a passive bass, unless you are talking about an acoustic. There's plenty of circuits in your amp, and they sound good, right? Like Rick Turner has said, it all depends on where the first gain stage is.

Low wind pickups are very full range, with a very extended high frequency response. You will hear every noise your fingers make.

Here's a clip of the pickups I was making. Each pickup was a dual blade humbucker, and run into its own JFET preamp.

SGD lo-z basspickup 05-23-06

The clip was recorded direct into a Roland digital mixer with no EQ.

[Triad]

Very nice... but of course magnetic pickups can't pick up what's going on in the instrument if this doesn't affect the strings. If you knock on the body with your fingertips, for example.
For "Passive" I obviously refer to high impedanze pickups without an onboard preamp.

[David Schwab]

Very nice... but of course magnetic pickups can't pick up what's going on in the instrument if this doesn't affect the strings. If you knock on the body with your fingertips, for example.

Sure they can. On my high impedance bass you can hear my strap lock squeaking when you move the strap. I can also tap on the body and you hear it. And the pickups are not microphonic at all.

But why would you want to hear handling noise anyway? It's just noise. Piezo pickups are more about hearing what the string is doing acoustically directly at the bridge saddle (or where you have them installed).

My point in posting that clip was your comment about low wind pickup with ceramic magnets being brittle, which clearly they aren't. And you can't get that tone passively unless your amp has a lot of gain, which would lead to noise, or you have a transformer at the amp. Obviously you realize that because you wound lower impedance pickups and want to use a TC3. Or are you just trying to be contrary? Passive basses are always losing the true tone of the pickup. It's not a bad tone — I make a lot of passive bass pickups — but it's not totally hi-fi/full range either.

[Triad]

I have more experience with AlNiCo5, that's the magnet type I used most... but good to know that Ceramic magnet works well, it's pretty bright in high impedance pickups too so I thought it could be "too much".
I want to get that "noise" 'cause for some techniques it can be nice... like on acoustic guitars played ala Michael Hedges, the player taps on the body of the instrument to get percussive effects. And with the on/off switch it can be removed, obviously, if the player wants the sound of magnetic pickups only. If the pickups are epoxy potted I don't know how they can pick up noises or other "effects"... if the strings don't move, the pickups have nothing to get, right? If you keep the strings muted and tap on the body how can you get a sound?