Low impedance Ceramic singles + Bartolini TC3?

[Mike Sulzer]

S 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

If you think noise from a 12AX7 is a problem when the gain needs to be two or three times higher, then must be using only ultra low noise preamps. In fact it is not a problem. Look how high the gain can be on a guitar amp and the problem is usually hum, not hiss from the first stage.

[David Schwab]

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".

That depends on the design of the pickup. Look how warm and dark some Bartolinis are, and they all use ceramic magnets.

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?

My pickups are epoxy potted, and they are still pretty sensitive to tapping the body. But not as much as a piezo of course.

As I said, I have an annoying squeak from the strap lock on one of my basses. It's bad enough to have made me want to fix it! You don't hear it when the band is playing, but you do if I'm playing by myself.

[David Schwab]

If you think noise from a 12AX7 is a problem when the gain needs to be two or three times higher, then must be using only ultra low noise preamps. In fact it is not a problem. Look how high the gain can be on a guitar amp and the problem is usually hum, not hiss from the first stage.

I'm talking about trough a typical bass amp. Something like a mic pre would work well. With a regular bass amp, to get a 2k pickup loud enough to use you really have to crank the gain up. And it will get noisy. And with a typical amp, you will hear a lot of hiss too. This is from actual experience, and not conjecture.

I was able to record those pickups by plugging into a mixer and cranking up the mic pre pretty high. Obviously that's not an issue for microphones, but they also have balanced lines. It was a much better situation having a simple jfet preamp in the bass.

That sound clip was through the jfet preamp. Different preamps I had, such as the Bartolini TC1, which had a lower input impedance, and a Barcus Berry preamp, gave different tonalities to the pickup. The Bart preamp made it sound almost like a high Z pickup. It didn't have that super extended high end.

[Mike Sulzer]

And it will get noisy. And with a typical amp, you will hear a lot of hiss too. This is from actual experience, and not conjecture.

I see; but I thought we were talking about Triad's pickup which has half the number of turns of a normal pickup; that is a lot more than 2K. Any amp using a 12AX7 front end which has significant noticeable noise with just a factor of two decrease in input level should be trashed. You did get my point about the guitar amp? Gain is turned way up to get over drive and distorted sustain and hiss from the tube is not a problem. And as for other types of noise pickup up between the bass and the amp, the lower impedance of the pickup is an advantage, not a disadvantage. Low impedance pickups do not pick up as much electrostatic noise.

[Triad]

Wow... and Bartolini says "It boosts the signal without affecting the sound" or something like that. I guess I'll have to build a few of those preamps myself in the near future. But I have no experience of that kind of stuff... I've made some crossover for cabs and of course hundreds of pickups but never put together a preamp.

[David Schwab]

I see; but I thought we were talking about Triad's pickup which has half the number of turns of a normal pickup; that is a lot more than 2K. Any amp using a 12AX7 front end which has significant noticeable noise with just a factor of two decrease in input level should be trashed. You did get my point about the guitar amp? Gain is turned way up to get over drive and distorted sustain and hiss from the tube is not a problem. And as for other types of noise pickup up between the bass and the amp, the lower impedance of the pickup is an advantage, not a disadvantage. Low impedance pickups do not pick up as much electrostatic noise.

Does he even have an amp with a 12AX7 front end? In fact, what kind of amp is that Mike? My Hartke LH-500 has a 12AX7 in the preamp, but an op amp front end. My BlueTube pedal has a 12AX7 and an op amp front end. Plus, he's also using a piezo pickup, and wants to blend them. He already asked about the Bartolini TC3 preamp.

"Half the number of turns" as relative to what? Half of 8,000 turns? Half of 4,000 turns? He didn't say. Then take something like an Alembic AXY stacked pickup. It reads about 7-8 k, yet the output is so low, you can't just plug it into an amp. I've tried it. So clearly he's asking about boosting the level of the pickups. Did he try them yet? Probably not. Maybe he doesn't have to, but it's not a bad idea and is pretty common.

[Triad]

Right, I think I should shed some light on the project...
It's a 12 strings Extended range bass, the pickups are two singles with Ceramic magnets. I usually turn them pretty hot as they have a pretty bright top end (around 9k turns). I've made this set with 4k turns and measured each one resistance... around 12k.
The amps I usually use are a Warwick Pro Tube IX (double preamp, one with 12AX7 and one is SS), a Pod XT+power amp and an old Trace Twin Valve (SS preamp on tube power section). I still have to test these pickups as I'm waiting for the strings and hardware to show up.

[Mike Sulzer]

Exactly, so you cannot possibly know whether he needs a preamp or not.

And do not think I am saying that a 12AX7 is super quiet. It is a quiet tube, but there are plenty of solid state devices that are far quieter. Especially for low impedance pickups! A tube, like a FET gives the best noise for audio when the source is transformed to a high impedance/voltage. This is because it has a significant amount of voltage noise, but very little current noise. This should be obvious from the physics of the tube: the grid operates as an electrostatic modulator of the current flow. Junction transistors operate more on current and tend to have very low voltage noise and higher current noise and thus are optimum for SNR when the source is transformed to a lower impedance. The solid state preamp in a bass amp would be good for whatever the guy who designed it wanted. It could be excellent for a low impedance, low voltage pickup, or not. Depending on the device use, the circuit, etc.

So you cannot say that you have to use a preamp for good SNR. There is no reason why the amp might not be just as good. It all depends.

Does he even have an amp with a 12AX7 front end? In fact, what kind of amp is that Mike? My Hartke LH-500 has a 12AX7 in the preamp, but an op amp front end. My BlueTube pedal has a 12AX7 and an op amp front end. Plus, he's also using a piezo pickup, and wants to blend them. He already asked about the Bartolini TC3 preamp.

"Half the number of turns" as relative to what? Half of 8,000 turns? Half of 4,000 turns? He didn't say. Then take something like an Alembic AXY stacked pickup. It reads about 7-8 k, yet the output is so low, you can't just plug it into an amp. I've tried it. So clearly he's asking about boosting the level of the pickups. Did he try them yet? Probably not. Maybe he doesn't have to, but it's not a bad idea and is pretty common.

[Triad]

Well but I'd prefer to have more signal and lower the gain instead of low signal and maybe not enough gain on the amp. I guess that designing a pickups set for a particular rig isn't the way to go, I'm looking more for a "one size fits all" solution

[Mike Sulzer]

And that is a good reason for using a preamp, along with the major one: increased flexibility in controlling the frequency response.

Well but I'd prefer to have more signal and lower the gain instead of low signal and maybe not enough gain on the amp. I guess that designing a pickups set for a particular rig isn't the way to go, I'm looking more for a "one size fits all" solution