Spector Tonepump specs, questions, wirings..

[grendle]

What Phat said.....

 

[grendle]

It would seem that Spector uses at least three different preamps. You have this one, then there is the US HAZ Labs preamp, and then this one from G&B in Korea:

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So you have at least three different circuit designs. There's nothing wrong with op amps, and when used properly they are better than JFETs as far as lack of distortion.

I think the thing to realize is if you are a manufacture of instruments, if you don't make your own electronics, you have to buy it from someone else. Then you are left to what the manufacturer of the electronics lists as their specs.

A lot of passive tone stacks are not flat when set on flat. The Fender style circuits only boost the bass and treble, and only cuts the mids. But they are highly interactive controls. Because of some insertion loss, you often have to boost the highs and lows slightly for flat.

I wouldn't worry about flat settings. Just dial in something that sounds good.

Yeah there's a lot of different pre's especially over the years, the HAZ (us 9v) , a Korean haz copy, a cz haz copy, emg BT, usa 18v, tone pump jr, tonepump, obp1, and I'm sure there's more. There a small shop and worry more about the basses than the info. The new site has a ton of good up to date info and historical info also.

The tone pump is probably the most misunderstood and underestimated pre they have had. It's a great pre, especially at 18v. The closest to the us 9v imo, but with a little more grit and bottom end available.

 

[PhatBasstard]

You should have a trim pot on the tone pump that controls the output (unless you have an early tonepump) . They come almost maxed out from the factory usually. There's a sweet spot around 3-4. That will bring the output down to normal levels. Any scratchy noise is not normal and is probably a dirty pot or possible bad solder joont, usually on the jack.

He said his bass is an '04. That would make it a non-trim TP (started in 2008) unless it's not original.

 

[SGD Lutherie]

This is an old thread, but reading the text in the first post from the preamp manufacturer:

Operational amplifiers, when they're overloaded- which is on beginning of nearly every tone, are saturated. When they're saturated, there is a short recovery time(about several milliseconds) and whole circuit doesn't work in this short time. The result is, that we lose signal- beginning of the tone, its attack. Valve(and this preamp) doesn't behave like this and when it's overloaded, it softly distorts second harmonical, which is octave, which doesn't matter to the sound. And the first signal after peak is immediately played.

Op-amplifiers based preamps often solve this problem using two 9V batteries. But the problem is not solved, it is just delayed and this peak could be problematic in signal chain in amplifiers, mixing consoles etc.

The result of JFETs using is, that instrument „articulates“ (because there's no loss on the beginning of the tone). Instrument is cutting through very good in the mix in low volumes, too, and tone is clear in every EQ setting, in studio or live situations.

This is absolute nonsense IMO. What they are referring to is slew rate, and in any op amp is fast enough for any bass signal. The worst you will get is a slight bending of the waveform that you will never hear. No properly designed preamp will ever saturate when you pluck a note. You would clearly hear that as distortion.

Some op amp based preamps distort on purpose, such as the SansAmp gear. And players love them.

JFETs tend to distort more like tubes, so they are often used for that purpose. But no onboard bass preamp is made to distort, so the point is moot. JFETs are used because they have a high input impedance, but when op amps are used, they are often JFET based op amps.

An op amp is actually a bunch of transistors on one die.

Also, you bass amp is filled with op amps, and has no problems with transients. Depending on the design of the onboard preamp it might work better on 18v to preserve transients.

 

[vgbob]

Anyone have any information on how to modify a Tonepump equipped bass with an active/passive switch? I have a Rebop I would like to have the option of running it in passive mode. Looking at the wiring it does not look like it is possible to insert a switch in the circuit to do this, as the preamp is between the volume and tone pots, so just bypassing the pre would disable the tone controls. Although if the Tonepump is like some other preamps there may be a way to do this, just
haven't found any reference so far.