Using a pedalboard power supply with an active bass

[kesslari]

I did some searching and saw some folks using a TRS cable and an additional box to power their onboard preamps.
Would it work (and why would it be a good/bad idea) to put a boss-style power jack in the control plate cover and wire that into the circuit so you could power the electronics from something like an MXR Iso-Brick?
My bass is on a stand which eliminates the "it will come out when I move around" issue.

 

[Warpeg]

The concept sounds solid, although the TRS cable concept makes more sense to me.

 

[Matt Liebenau]

To me, at least, the TRS cable makes more sense. Only one cord going into the bass. One less thing to hook up or step on.

The downside with either system is you're married to that. If the cable gets damaged, lost, forgotten, etc you're stuck. I'd probably make up 2 or 3 of them to have in my bag but I'm wierd that way.

 

[Killed_by_Death]

Seems like you'd have to re-wire your bass internally as well, which would make it only useable with the external power source.
You'd have to connect the ring of the jack to the preamp's + Volts in & ground the (-) side of the preamp.

As stated, if you lost that power cable with the TRS connector, you're out of luck.
unless your bass has a passive/active switch

 

[John Burgess]

A battery is a very quiet fully floating voltage source. It solves more problems than it causes.

You would have to be careful how a particular DC power supply is referenced to your signal earth. Coupled with the fact that you will likely be using a switchmode supply, noise will probably be an issue to some extent.

 

[Killed_by_Death]

Yeah, you'd need a pretty good power supply not to induce A/C ripple into the signal.

 

[kesslari]

A battery is a very quiet fully floating voltage source. It solves more problems than it causes.

You would have to be careful how a particular DC power supply is referenced to your signal earth. Coupled with the fact that you will likely be using a switchmode supply, noise will probably be an issue to some extent.

Curious as to why this would be more of a problem for a preamp in the bass than for a preamp on a pedal board.

 

[kesslari]

@Passinwind any thoughts?

 

[Matt Liebenau]

Curious as to why this would be more of a problem for a preamp in the bass than for a preamp on a pedal board.

Not an expert but my guess is that many or most pedals have some degree of filtering on their power input and onboard bass preamps don’t.

 

[Passinwind]

@Passinwind any thoughts?

I ran a two cord system for quite a few years. It was a riff on the Alembic thing, with +/- 15 volt rails. Eventually I moved to a single 4 conductor cable, but that locked me into having a proprietary cable and no good fail safe if the power supply died. It sounded great though. Nowadays my own onboard designs all draw less than 1mA though, so replacing a battery twice a year or less doesn't really bother me.

The amount of supply filtering that I've seen in commercial onboard designs has been all over the map. It's generally good practice to include a fair amount of capacitance, which helps compensate for the rising internal resistance as a battery drains. Not all onboards have reverse polarity protection either, which is just one more "gotcha" to watch out for. But in general, I think that not using batteries is a worthy goal, and a properly shielded quiet outboard supply can and should work quite well in many cases.

 

[ELynx]

My two cents, but with TRS plug be sure to see how contact is made during insert/remove of plug.
I think that there might be a moment when plug tip is connected to jack ring and plug ring is connected to jack sleeve. This way you have power on ground (sleeve) and connection through signal, I think.
Just try it with some cable tester, it will show you what connections were made. In my experience plugging TRS anything will cause some "temporary" connections.

 

[Turxile]

It's not a bad idea, but it's not a good idea either. I'm saying that because I don't see the problem it fixes. Batteries are not hard to handle, they last a long time, and they work.
My guitarist is using a mobile phone power bank to power his small board, with a usb cable. If that works then a decent power supply will as well.

 

[kesslari]

It's not a bad idea, but it's not a good idea either. I'm saying that because I don't see the problem it fixes. Batteries are not hard to handle, they last a long time, and they work.

My Bart pre - I’d agree. My filter pre goes through a battery in about 30 hours and that’s getting to be a hassle. Sure sounds great though

 

[96tbird]

Its a cool idea but i would personally go with a full on battery run pedal board and run the trs from that because that’s me.

My guitarist is using a mobile phone power bank to power his small board, with a usb cable. If that works then a decent power supply will as well.

^Fun stuff. I used some RC lithium 11.1v batteries and put together a power box with a voltage buck and volt meter on my wee tuner/ab switch board just so I didn't have more wires on stage or have to use inernal battery on my tuner. 3000 mah batteries run my tuner for a very long time: about 200 hours. Would be fun to set it up to power an active. Put a trs jack in the power box and a signal out out jack and bobs yer uncle

 

[Matt Liebenau]

That's a thought. Something like the Big Joe battery/power supply might work for something along those lines.

 

[kesslari]

This wound up being much easier than I thought, with a 12v power supply bought here on TB, a TRS cable, and a battery "jumper" to clip on the battery lead. No rewiring required.
If I forget the power supply or have a problem, unclip the jumper and clip in a battery.

Again, if it was my old Bart preamp I'd have left it alone, but I love this pre and it eats batteries. No more!
Plus it sounds GREAT at 12 v.

 

[Matt Liebenau]

Nice. Glad it worked out.

 

[richntiff]

I read stuff like this and then I realize maybe ignorance is bliss? I play active 18v basses into preamp pedals and compressors into stacked combo amps - I think my tone is killer. Honestly - am I missing something ???

 

[kesslari]

I read stuff like this and then I realize maybe ignorance is bliss? I play active 18v basses into preamp pedals and compressors into stacked combo amps - I think my tone is killer. Honestly - am I missing something ???

If your tone is killer, you're good! For me - the rate at which this new preamp was going through batteries was enough of a hassle that I wanted an alternative.

 

[richntiff]

If your tone is killer, you're good! For me - the rate at which this new preamp was going through batteries was enough of a hassle that I wanted an alternative.

I re-read my post, and it sounds snarky - it really wasn't meant that way at all. I just meant that sometimes I feel like I should spend more time understanding the electric/techie side of this stuff.