Stupid question - why do some basses have two batteries?

[Woodinblack]

But that doesn't give you any real advantage over a 9v supply, not like an actual 18V where you can use the zero as the centre crossing point.

[Baloney Balderdash]

The preamp in my Aria Pro II Laser Electric Classic, produced in 1986, runs on 2 9V batteries as well.

 

Edited July 31, 2023 by Baloney Balderdash

[ahpook]

1 hour ago, kodiakblair said:

What did you solder ?

 

 

This, bang on.

[LowB_FTW]

@ahpook and @kodiakblair thank you both very much for this exchange.

 

Mark

[ahpook]

8 minutes ago, LowB_FTW said:

@ahpook and @kodiakblair thank you both very much for this exchange.

 

Mark

 

From one Mark to another,  my pleasure !

[kodiakblair]

5 hours ago, Woodinblack said:

But that doesn't give you any real advantage over a 9v supply, not like an actual 18V where you can use the zero as the centre crossing point.

Best tell EMG, they've used that method for years.

[Woodinblack]

23 minutes ago, kodiakblair said:

Best tell EMG, they've used that method for years.

 

That is because it is how they designed their preamp to function - it sounded like you were just taking some preamp designed to run at 9v and running it at 18V.

I guess I just don't get what is trying to be achieved here. or are we trying to extend tonewoods to electronics now?

 

[rwillett]

On 30/07/2023 at 18:36, White Cloud said:

For what it's worth I don't think this was a stupid question at all. 

 

I didn't think it was a stupid question either, what was stupid was me thinking I knew that answer. After reading this thread, I'm not sure I'm that much wiser but I now appreciate it's not as simple as the simple and stupid answer I had thought of. 

 

Always nice to learn something new. 

 

Rob

Edited August 1, 2023 by rwillett

[kodiakblair]

@Woodinblack

 

You convert Tone Monster preamps from 9v to 18v the exact same way.

 

Main reason for running at 18v is longer spells before changing batteries. I've saw the term 'headroom' bandied about but since EMG tell you running at 18v doesn't increase the output, stays the same as 9v, I've no idea what form this headroom takes ; placebo does come to mind 😄

[Woodinblack]

Yeh, but powering something that uses a 9v battery with an 18V battery doesn't make it last twice as long - if you have to make a zero crossing, you have a resistor chain in the middle. An amp is a series of resistor chains and as I = V/R, if you double the V, you double the I going through, so you are using more power in the same circuit. 

If there is any problem with the time a battery lasts in an active bass, its time to find a reason - a battery in a bass pre-amp should last ages.

[Hellzero]

2 minutes ago, Woodinblack said:

Yeh, but powering something that uses a 9v battery with an 18V battery doesn't make it last twice as long - if you have to make a zero crossing, you have a resistor chain in the middle. An amp is a series of resistor chains and as I = V/R, if you double the V, you double the I going through, so you are using more power in the same circuit. 

If there is any problem with the time a battery lasts in an active bass, its time to find a reason - a battery in a bass pre-amp should last ages.

That's why I've always preferred those fake 18 Volts preamps running on 9 Volts, like, for instance the Mike Pope Flexcore.

[NancyJohnson]

I had an EMG active pickup thingie in an old Precision bass, ran it on an 18v loom.  Allusion was that this would (somehow) allow the circuit to boost things.  So of course, we were all running these on two 9v batteries.

 

Uncertain how, if you have a circuit that works at 100% on 9v will work outside of it's specification if you double the input voltage.

[hill76]

22 minutes ago, NancyJohnson said:

I had an EMG active pickup thingie in an old Precision bass, ran it on an 18v loom.  Allusion was that this would (somehow) allow the circuit to boost things.  So of course, we were all running these on two 9v batteries.

 

Uncertain how, if you have a circuit that works at 100% on 9v will work outside of it's specification if you double the input voltage.

Genzler re/Q pedal quotes higher input headroom depending on supply voltage (9-18v).

[NancyJohnson]

9 hours ago, hill76 said:

Genzler re/Q pedal quotes higher input headroom depending on supply voltage (9-18v).

 

Headroom is an odd thing. 

 

If you have a 900w amp (yes) and you only play at 30% of it's perceived output because it's goes so loud (yes), the headroom element is quantified as the unused 70%.  While that 70% demonstrably represents the ability of the amp to go louder, it also leads that at comfortable levels (the 30%) the amplifier isn't being driven so hard that it goes all mushy.

 

Now headroom in pickups/circuit?  If the the pickups work perfectly well at 9v, sticking an additional 9v into the circuit isn't going to realistically provide 'headroom' per se.  Assuming the 18v power is within the capacity of the circuit and doesn't fry anything, the additional voltage isn't going to do anything radical; the circuit cannot perform outside it's designated parameters, it won't go louder or add addition tone as it's limited by design (I didn't really notice any difference when I did it). 

 

I've read up enough on this over the years, people saying when they hit hard the EMGs would distort/clip, whereas with an 18v they wouldn't (resolution, lower the pickups or turn the output pot on the bass and/or learn how to adapt your right hand technique).  Possibly less output noise from the bass (never suffered this with any bass, there's a thing called grounding, or you can drop the earth on a DI box).

 

Thing is we do these tweaks because we're bass players and because we feel we need to.  These things make little or no difference once you're in a full-band context.

[ahpook]

30 minutes ago, NancyJohnson said:

Thing is we do these tweaks because we're bass players and because we feel we need to.  These things make little or no difference once you're in a full-band context.

 

You're missing the whole joy of soldering angle

 

Oh, did I mention that before ?

[NancyJohnson]

18 minutes ago, ahpook said:

 

You're missing the whole joy of soldering angle

 

Oh, did I mention that before ?

 

[ahpook]

2 minutes ago, NancyJohnson said:

 

 

Me, aged 9, if I were a girl

[Woodinblack]

2 hours ago, NancyJohnson said:

 

 

sticking an additional 9v into the circuit isn't going to realistically provide 'headroom' per se.

 

Indeed - and this is what always gets me. If your preamp 'works better' at 18v than 9V, it means it isn't working properly at 9v.

[NancyJohnson]

2 hours ago, Woodinblack said:

 

Indeed - and this is what always gets me. If your preamp 'works better' at 18v than 9V, it means it isn't working properly at 9v.

 

I suppose you could also look at it by saying the circuit was designed to tolerate 18v and should be 18v, but operates okay at 9v and is sold as such.  

 

Oddly - and swerving the thread a little - I have a Geddy Lee Tech21 thing - the DI-2112.  It works fine off a 9v PSU, but it sounds better/fuller with an 18v supply (to quote Tech21 'for increased headroom and clarity').  

[Chienmortbb]

On 29/07/2023 at 23:17, itu said:

No, I haven't been very active with designing circuitry, although some time ago I fell in love with the designs of our own @Passinwind. His work is very interesting. I wish at least one preamp will find its way to the basses I work with.

+1

[bloke_zero]

19 hours ago, NancyJohnson said:

 

I suppose you could also look at it by saying the circuit was designed to tolerate 18v and should be 18v, but operates okay at 9v and is sold as such.  

 

Oddly - and swerving the thread a little - I have a Geddy Lee Tech21 thing - the DI-2112.  It works fine off a 9v PSU, but it sounds better/fuller with an 18v supply (to quote Tech21 'for increased headroom and clarity').  

I've got some EMG's which, to my ears, did sound much clearer and less fuzzy at 18v like you say.

 

In terms of it not working properly at 9v - I guess part of the equation is battery realestate - it's relatively easy to find room for 1 9V (say in the channel from the pickup in a p-bass) but harder to find room for 2 without getting serious with a router.

[BigRedX]

Of course it's simpler to ditch the on-board pre-amp completely, not have to worry about batteries and use the tone controls on your amp that will be running off the voltage supply they were designed for.

[Woodinblack]

I think it is just much simpler to use a preamp that works at the battery voltage provided

[hill76]

On 02/08/2023 at 09:28, NancyJohnson said:

 

Now headroom in pickups/circuit?  If the the pickups work perfectly well at 9v, sticking an additional 9v into the circuit isn't going to realistically provide 'headroom' per se.  Assuming the 18v power is within the capacity of the circuit and doesn't fry anything, the additional voltage isn't going to do anything radical; the circuit cannot perform outside it's designated parameters, it won't go louder or add addition tone as it's limited by design (I didn't really notice any difference when I did it). 

Look at it the other way round - a circuit that is designed to run optimally at 18v can also perform adequately at 9v, but with less headroom. You will find many pedal manufacturers quoting a difference in tone or headroom at different supply voltages.

[tauzero]

Although the headroom should be perfectly adequate at 9V, as the signal is typically around 150mV p-p, maybe as high as 300mV, but still a good margin from the supply voltage.