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9 volts vs. 18 volts

#21
VODFleisch said:
EMG recommends the 18v config in the wiring instructions of the BTS system. Unless they cut a side deal with Duracell.....
Click to expand...

It seems that EMGs do have more of a need for 18 volts than other manufacturers. Someone mentioned 'gain staging' and there is also the fact that if you have a complete EMG system with active pickups and active preamp, the pickups themselves will draw about 1.5 volts from the battery, leaving just 7.5 for the pre, meaning a lot less headroom to deal with the probably quite high output from the pickups.

Bartolinis are nearly all passive and pretty low output so maybe my experiences I posted about earlier aren't so relevant. With EMGs I can see why 18 would make sense. Although it wouldn't actually be 18, would it? More like 16.5. If the pickups are drawing off some current.

Or am I completely wrong? Can anyone tell me what would be the difference in voltage use between an active EMG pickup with no active preamp and an active EMG pickup with an active preamp? Would you ever need 18 volts for an EMG if you were just using a passive preamp?
 
#23
Belka said:
I don't quite understand what you're trying to say and I'm no expert but I found the following from the Bartolini website:

In 9 volt operation the NTBTG uses approximately 750 microamperes of current from 1 - 9 volt battery. This means 1 month of continuous duty or more than 6 months of average usage. In 18 volt operation the NTBT-918 uses approximately 1000 microamperes of current from 2 - 9 volt batteries. This means more than 3 weeks of continuous duty or more than 4 months of average usage.
Click to expand...

Because preamps are Ohmic devices, increasing supply voltage also increases current. But those numbers don't make much sense. 9V at 0.75mA is a resistance of 12k Ohms. 18V at 12k Ohms is 1.5mA, not 1mA.
 
#24
I have a question about farting out. If I run straight in to the amps, no farting out. If I run in to my WTDI straight to the PA I have to pull the bass volume down to 1/4 or it will fart out in the PA. This is with my '95 Pedulla Thunderbolt (9v system). It does not do this with my passive Fender. I would have thought an 18v system would increase the farting due to increased voltage.
 
#25
Running at 18v doesn't increase the out put, it only gives the pickups and pre more voltage and current to work with. When you hit the string you generally don't get that momentary overload / distortion from the pickup at 18v. The extra voltage and available current let the pickup's preamp ( EMG's internal preamp) process the note and attack more cleanly and fully. What you get with them is more fidelity ( you hear every part of the attack more clearly and undistorted) and more headroom ( you can hit the string as hard as you like and not have any of the overload effect). It does not increase the output signal or make it any hotter. 18v is for the preamp inside the pickup, not the basses onboard preamp generally.

Think of it as if you have a generator powering a bunch of light bulbs. Turn them all on one at a time and they all work , but get just a little dimmer every time another is turned on. Replace the generator with a bigger one and do the same, the bulbs all still work but are brighter than with the smaller generator. Same idea basically. That's for EMG's I don't have experience with any others at 18v so ymmv. But it works great in both basses and guitars. Think EMG 81's are cool? Try running an 85 at 18v! Eats its lunch. Lol
 
#27
AdamR said:
My Schecter C1 has a 81/65 combo in it. Never thought to try it at 18V
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More noticeable on the guitar pickups IMO. The chunk on the bottom end becomes more defined and you'll get more articulation. I run a single 85 in my esp (ex) at 18v and its a beast distorted, but the cleans are even better. You don't get that harsh pick attack on the cleans. Just nice crisp articulation. ;)
 
#28
Swipter said:
I have a question about farting out. If I run straight in to the amps, no farting out. If I run in to my WTDI straight to the PA I have to pull the bass volume down to 1/4 or it will fart out in the PA. This is with my '95 Pedulla Thunderbolt (9v system). It does not do this with my passive Fender. I would have thought an 18v system would increase the farting due to increased voltage.
Click to expand...

The 9V fartout problem with EMG's is strictly related to the way their internal gain-staging works. Supply voltage should not be confused with how many volts a preamp can swing at the output.

A 9V preamp designed for maximum output can theoretically pass peaks of at least 6 or 7 volts, and an 18V EMG system does NOT output an 18V signal! That would be ridiculous, as it would blow the face off even a pro power amp. They are typically set up to give full output on a 2 volt sine wave.

Anyway, we were originally talking about internal clipping, before the output from your bass hits the rest of your signal chain. That doesn't mean that you can't also have issues with pedals or amps that have limited headroom.

While running EMG's at 18V doesn't increase the gain or give you more average level, it does allow your onboard electronics to pass bigger peaks. If you're slapping the heck out of your bass, for example, you will be passing transients that would have been suppressed at 9V.

Your WTDI (like the WTX micro amps that it's based on) has a well-known achilles heel: a compressor/limiter that sounds bad when pushed too hard. In that particular situation, a lower-output passive bass will sound better for the simple reason that it doesn't trigger the Eden's weak spot.
 
#29
I'm resurrecting a year old thread here ... but I made this today. I shortened a 2xAAA battery holder by cutting out a section in the middle and then wrapping the back and sides with carbon fiber so the glue joint would be strong enough to hold together. two 12 volt A23 batteries for 24 volts in a small package.

note the battery connector must be reversed since it's coming FROM the battery not going to one -- also, I had to trim away any carbon from the area where the black and red leads connect, the carbon was conducting current and getting hot. Once that was done, it works great - just don't test it with your tongue like you do a 9volt -- haha -- don't ask me how I know.
24volt_CarbonFront.jpg

24volt_CarbonBack.jpg
 
#30
Double check with the manufacturer of your preamp before you run it at anything more than 9 volts. Especially if it's an old MM 2-band or something. You'll almost certainly cook the electrolytic caps. If it's an old discrete fet circuit (like sadowsky) there's also a chance you'll also excede the max voltage across the transistors. (Silent bass, with burning plastic smell.)

the carbon was conducting current and getting hot.
Click to expand...

I've driven across Australia a few times in prototype solar-electric vehicles made almost entirely of carbon fibre. In torrential rain, things can get a bit, umm, tingly... :wideyed:
 
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#32
Belka said:
It seems that EMGs do have more of a need for 18 volts than other manufacturers. Someone mentioned 'gain staging' and there is also the fact that if you have a complete EMG system with active pickups and active preamp, the pickups themselves will draw about 1.5 volts from the battery, leaving just 7.5 for the pre, meaning a lot less headroom to deal with the probably quite high output from the pickups.

....
Or am I completely wrong? ...
Click to expand...
Yes you are completely wrong, the voltage is not "shared" between the pickup/s and the pre, they will both receive whatever the battery voltage is.
 
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#33
delta7fred said:
Yes you are completely wrong, the voltage is not "shared" between the pickup/s and the pre, they will both receive whatever the battery voltage is.
Click to expand...

Yeah, that's not how electricity works, at all.

Belka said:
Or am I completely wrong? Can anyone tell me what would be the difference in voltage use between an active EMG pickup with no active preamp and an active EMG pickup with an active preamp? Would you ever need 18 volts for an EMG if you were just using a passive preamp?
Click to expand...

Pickups and preamps don't change the supply voltage. While it is possible to place a tremendous load on a battery that causes voltage to drop, you are drawing so little current that the battery really doesn't even know that it's supplying power to the circuit.
 
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#36
I've tried 9 vs 18v in my EMG basses with BQC and BTC pres, and I've been less than impressed with the results, to be honest. About the only difference I heard was they don't engage limiting quite as much when you dig in super hard. Which is nice, but the limiting you get at 9v isn't very much at all, and for me it wasn't worth the effort. Plus one of my basses with the BQC has no room for a second battery anyway. So I'm perfectly fine with only one battery.
 
#37
So from the battery box to the battery clip you wire red to black and black to red?
Thx!
Barry

AndyPanda said:
I'm resurrecting a year old thread here ... but I made this today. I shortened a 2xAAA battery holder by cutting out a section in the middle and then wrapping the back and sides with carbon fiber so the glue joint would be strong enough to hold together. two 12 volt A23 batteries for 24 volts in a small package.

note the battery connector must be reversed since it's coming FROM the battery not going to one -- also, I had to trim away any carbon from the area where the black and red leads connect, the carbon was conducting current and getting hot. Once that was done, it works great - just don't test it with your tongue like you do a 9volt -- haha -- don't ask me how I know.
View attachment 450285
View attachment 450287
Click to expand...
 
#38
bazzanderson said:
So from the battery box to the battery clip you wire red to black and black to red?
Thx!
Barry
Click to expand...
For the device I made, yes, that is how I had to do it. But I believe you can simply buy ready made battery holders that already have the clips correct. I wasn't aware anything like that already existed to be purchased so I made my own.

Also ... in other threads I recorded same bass, played as hard as I could play it, at 9V and at 24V and compared waveforms ... I couldn't see any indication of clipping or compression at 9V so IMO the higher voltage doesn't buy you anything.
 
#39
Thanks for the info. I went with 18volt in my Dixie bass (double EMG PXs) with no active preamp. I did notice a slight bump in volume (slight) but the change to the notes....just their expressive, faster nature (quicker attack) was definitely noticeable. I was going to do the 18volt mod to my Gibson Thunderbird (EMG DC and CS, again...with no preamp) but there's not enough room for two 9volt batteries so I'm thinking I'm going to do the 24volt mod. I did find a few pre-made 24volt mod / boxes on Ebay so I think I'm going to go that route. Did the basses you tried it on have active preamps? I'm wondering if the bump in volume I noticed is because it's just a volume, volume, tone set up with no preamp?

AndyPanda said:
For the device I made, yes, that is how I had to do it. But I believe you can simply buy ready made battery holders that already have the clips correct. I wasn't aware anything like that already existed to be purchased so I made my own.

Also ... in other threads I recorded same bass, played as hard as I could play it, at 9V and at 24V and compared waveforms ... I couldn't see any indication of clipping or compression at 9V so IMO the higher voltage doesn't buy you anything.
Click to expand...
 
#40
My bass had two EMG (P-J) pickups and the EMG preamp with bass/treble and blend. I've had no trouble with it since making that little 24v battery pack. But I did check the specs from EMG first to make sure it could take that much voltage. Some other brands may not like that high a voltage (mainly depends on the voltage ratings of any electrolytic capacitors they use)
 

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