18v and 9v active circuit

[flyfisher]

[quote name='BigRedX' post='954380' date='Sep 13 2010, 09:16 AM']And while we're on the subject of on-board pre-amps maybe someone with a good knowledge of electronics (flyfisher?) can explain the attraction to me. I already have tone controls on the pre-amp in my rack, and I would have thought that it's much easier to build a good noise-free tone-shaping circuit when you don't have to worry about getting it small enough to fit into the control cavity of a bass and having to be powered by batteries?[/quote]

Well, the only technical justification I can think of is that an on-board preamp will minimise the length of cable that a very small signal has to travel along, which will (theoretically) reduces the susceptibility to noise pick-up on the way to the main amp or rack-based preamp.

But we all know that passive basses don't really suffer from inherent noise problems, or none that make them unacceptable otherwise there would be no passive basses, which is why I qualified the above with "theoretically" lest we descend into the realm of hi-fi voodoo and start discussing the merits of gold-plated mains plugs.

I agree there are ergonomic and physical issues that are probably more important, which is exactly what I meant with my earlier comment that 'engineering is the art of the compromise'.

There are lots of different ways of making a vibrating length of metal make a very loud noise and different people will inevitably choose different set-ups. Ultimately, if you like the tone that comes out of your rig then it will suit you, no matter how it has been created.

[EBS_freak]

I'm an expert on active circuits, lol jk. I'm strictly a passive man.

[stingrayPete1977]

[quote name='EBS_freak' post='954779' date='Sep 13 2010, 02:14 PM']I'm an expert on active circuits, lol jk. I'm strictly a passive man.[/quote]
Haha!

[tauzero]

I remain completely unconvinced about the headroom explanation. The signal coming from a bass is of the order of 100-200mV p-p, which is considerably smaller than the supply voltage. It's like saying that you run less risk of banging your head if you jump up and down in the Vertical Assembly Building than if you jump up and down in St Paul's Cathedral.

[Dood]

[quote name='tauzero' post='957083' date='Sep 15 2010, 12:13 PM']I remain completely unconvinced about the headroom explanation. The signal coming from a bass is of the order of 100-200mV p-p, which is considerably smaller than the supply voltage. It's like saying that you run less risk of banging your head if you jump up and down in the Vertical Assembly Building than if you jump up and down in St Paul's Cathedral.[/quote]

I'm 6ft 3! If I jump in my front room I will bang my head!

[BottomEndian]

[quote name='tauzero' post='957083' date='Sep 15 2010, 12:13 PM']The signal coming from a bass is of the order of 100-200mV p-p[/quote]
[url="http://www.bassplayer.com/article/rick-turner-piezo/mar-05/3368"]According to Rick Turner[/url], a piezo pickup can have transients exceeding 12V. Don't know how true that is, but I can certainly push the 9V onboard pre in my Skelf into distortion if I really dig the hell in.

[flyfisher]

[quote name='tauzero' post='957083' date='Sep 15 2010, 12:13 PM']I remain completely unconvinced about the headroom explanation. The signal coming from a bass is of the order of 100-200mV p-p, which is considerably smaller than the supply voltage. It's like saying that you run less risk of banging your head if you jump up and down in the Vertical Assembly Building than if you jump up and down in St Paul's Cathedral.[/quote]

A lovely analogy that could be applied to all manner of things, especially in the hi-fi and car worlds.

[tauzero]

[quote name='BottomEndian' post='957125' date='Sep 15 2010, 12:53 PM'][url="http://www.bassplayer.com/article/rick-turner-piezo/mar-05/3368"]According to Rick Turner[/url], a piezo pickup can have transients exceeding 12V. Don't know how true that is, but I can certainly push the 9V onboard pre in my Skelf into distortion if I really dig the hell in.[/quote]
I had to increase the gain on the preamp of my Ashbory because the output (after going through a Baxandall-type network which IIRC has a gain of 1/3, then through an op-amp gain stage with a gain of between 3 and 4, frequency-dependent) was less than half that of my active basses, and even further down compared to my passive Peavey Grind. You'd need to hook your bass up to a scope to see whether you were actually hitting the limits or if it was mechanical distortion.

[BottomEndian]

[quote name='tauzero' post='957252' date='Sep 15 2010, 02:52 PM']mechanical distortion.[/quote]
Taking the piezo material itself beyond its working limit? Now there's something I hadn't considered. These piezo things are still kind of voodoo to me.

[tauzero]

[quote name='BottomEndian' post='957266' date='Sep 15 2010, 03:08 PM']Taking the piezo material itself beyond its working limit? Now there's something I hadn't considered. These piezo things are still kind of voodoo to me.[/quote]
Or possibly bouncing the string on the bridge saddle, or maybe even the string rattling against the fretboard.

EDIT: Just to clarify, by mechanical, I meant anything involved in the physical side of the string's causing the piezo to distort and thus generate the signal, rather than the electrical, which is any distortion caused to the signal by the circuitry that it travels through.

Edited September 15, 2010 by tauzero

[BottomEndian]

[quote name='tauzero' post='957276' date='Sep 15 2010, 03:13 PM']Or possibly bouncing the string on the bridge saddle, or maybe even the string rattling against the fretboard.

EDIT: Just to clarify, by mechanical, I meant anything involved in the physical side of the string's causing the piezo to distort and thus generate the signal, rather than the electrical, which is any distortion caused to the signal by the circuitry that it travels through.[/quote]
Yep, I get you. Although in my case, the string rattling against the fingerboard is generally a [i]good[/i] thing. Mwaaaaaaahhh!