# [Tech] HOW TO: The reversible 18v mod!



## darren (Sep 6, 2008)

It's fairly well known that EMG preamps are designed to work with as much as 27 volts. The 18 volt modification is pretty common among bass players, as it offers more dynamic range and greater headroom, reducing the amount of built-in compression that the EMG preamp performs in 9 volt operation. However, on EMG's own advice, there's not much benefit of 27 volts over 18, so i'll focus on the 18 volt mod here.

There are a few scattered threads on the forum asking about the 18v mod, so i thought i'd do one comprehensive writeup incorporating everyone's input on how to do the 18v mod. Of course, you can do this by modifying the guitar's original wiring, but when i saw this idea, i thought it was pretty clever, and 100% reversible without changing your guitar's original wiring. (Making it really easy to switch back if you prefer 9 volt operation of your EMGs.)

The idea is to bump the voltage feeding the EMG preamp to 18 volts in order to increase dynamic headroom. You can run two 9 volt batteries in parallel to double battery life, but that's not the point of this exercise.

All you need is a soldering iron, some electrical tape and/or heat shrink tubing and three 9 volt battery clips from Radio Shack (or somewhere similar).

And, since a picture is worth a thousand words, i'll save you from any further reading by providing a handy diagram which explains it all:







It's also been asked a number of times if the 18 volt mod will benefit other active pickups or preamps. The best advice is to consult the preamp's manufacturer. I believe Bartolini preamps do well with 18 volts. However, Seymour Duncan Blackouts have a preamp that's designed to offer optimum headroom at 9 volts, making the 18 volt mod unnecessary.

*DISCLAIMER: All modifications, including this one, are undertaken at your own risk. If you screw something up and you blow up your guitar, your pickups/electronics, your cables, your pedals, your amp or yourself, it's your own damn fault. You will not hold the author of this post or sevenstring.org liable for any personal injury or loss or damage of personal property that may arise from this modification.*


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## yellowv (Sep 6, 2008)

This has been posted before, but your diagram is better.


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## darren (Sep 6, 2008)

Yes, i know it's been posted before, but the information is really scattered across a few disparate threads that are hard to search for because "EMG" and "18v mod" all fall below the forum's search threshold. 

And my diagram is better. 

I've done a quick A/B test with the EMG 808 in my Agile Intrepid Pro. I played something really simple, clean and distorted to try and get a sense for the differences. I tried to include regular/lighter picking as well as slamming the strings harder in both clean and distorted modes.

In the left channel are the 9v tracks, and in the right channel are the 18v tracks. The cleans are totally unprocessed. Just the guitar into my Line 6 DI, and through GearBox on the "no amp" setting direct into GarageBand. No post-processing was used. The distorted tracks are the same Recto patch i've used on other recordings.

Soundclick: EMG 808 9v vs. 18v

Initial impressions: 

My setup makes it hard to do quick pans between the left and right channels, but there are definitely differences in tone and responsiveness. Essentially, everything that's been said about the 18v mod is true... there are much greater dynamics, which you can hear and also see on the waveforms. There's a lot more "air" in the sound when running 18v. It's more apparent on the cleans than the distorted sound. When playing with a lighter touch, it's quieter, and when really slamming the strings, it's louder. In 9v mode, the amplitude of the signal coming out of the guitar is much more even.

Tonally, i actually like the 9v sound a bit better. It has a bit more depth to it to my ears. The 18v has a touch more "presence" at the super-high end of the sonic spectrum. That said, i'd gladly swap more dynamic range and responsiveness for a minor tonal difference that i can tweak back in with EQ. 

So there it is... my pseudo-scientific comparison of an EMG 808 in 9v and 18v modes.

My apologies for some audio glitching on the tracks... i haven't really got my system optimized for running audio apps, so there's a bit of weirdness at times. Sometimes it makes it into the recordings, other times not.


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## Josh Lawson (Sep 6, 2008)

I added tags to this because I think it is a very important thread for many users. This will hopefully help searches in the future.


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## Elysian (Sep 6, 2008)

hmmm so i could run 4 batteries, a pair in series connected in parallel with a pair in series to double the voltage and battery life?  thatd be crazy battery life.


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## darren (Sep 6, 2008)

Good call on the tagging.


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## darren (Sep 6, 2008)

Elysian said:


> hmmm so i could run 4 batteries, a pair in series connected in parallel with a pair in series to double the voltage and battery life?  thatd be crazy battery life.



You'd pretty much need to route a whole separate compartment just for the batteries! Maybe just stick a lantern battery in there.


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## angus (Sep 7, 2008)

I did a similar thing to one of a friend's studio instruments- a custom EMG. I wired a switch in so he could swap on the fly from 9V to 18V. They sound very different, and it allows you to have a lot more freedom to change the tone on the fly in the studio. Not at all practical for live work, but a very very easy mod. 

Nice diagram, but the way. Love the realistic shading on the batteries!

I don't know about the guitar pickup stuff, but EMG bass preamps can actually be wired up to 45V (I think Seymour Duncan's can, too). Absolutely no reason to, but you can. I can't remember if their active bass pickups go up to 27 or 45V. I've never heard of someone actually going beyond 18 with them, though.


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## neoclassical (Sep 7, 2008)

Hmmm. Never thought it would be that easy. I'll have to try it this week. I've been interested in the difference.

Thanks, 
Adam


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## eleven59 (Sep 7, 2008)

Couldn't you do this with just one extra battery harness? 

Just hook up the positive of one battery and the negative of the other battery to the stock harness, then use the second harness to join the other two poles, and solder and tape the wires on the second harness together?


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## darren (Sep 7, 2008)

Yes, you could do that, too! Smart guy! I forgot about that one. 

This way is a little more idiot-proof, though, and allows one to more easily attach the wiring harness to the two batteries (in my case, they're taped together, as there's only one battery clip in the Intrepid's control cavity) then insert the batteries and hook them up to the stock battery clip. And if you don't have room to put the batteries exactly side-by-side, you can position the second battery wherever you need it, and can adjust the wire lengths to suit.


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## eleven59 (Sep 7, 2008)

Like this:


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## eleven59 (Sep 7, 2008)

darren said:


> Yes, you could do that, too! Smart guy! I forgot about that one.
> 
> This way is a little more idiot-proof, though, and allows one to more easily attach the wiring harness to the two batteries (in my case, they're taped together, as there's only one battery clip in the Intrepid's control cavity) then insert the batteries and hook them up to the stock battery clip. And if you don't have room to put the batteries exactly side-by-side, you can position the second battery wherever you need it, and can adjust the wire lengths to suit.



Ah yeah, valid point. I think if I end up trying this with my Hellraiser, I'll be doing it the way I suggested, with the two batteries taped together and taped into the back of the guitar, as it only has room for one battery in its battery compartment


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## darren (Sep 7, 2008)

Yeah, that kinda sucks. But it's worth trying out, for sure. It's a tough call on 9v vs. 18v for me. The 808 in 9v mode had more girth to the tone, but the dynamics were very even overall. Going to 18v opened it up quite a lot, made the dynamics a lot better, and to the best of my ability to describe it, essentially shifted the "resonant peak" upwards. 

You can especially hear it on the long clean sustained tail in my demo recording. If you listen to the overtones on the 9v tail, it has a slight "oooooh" tonality to it. On the 18v side, it sounds more like an "aaaaah". It's very subtle, but it's there. It's not so much a shift in the fundamental tone of the pickups or the guitar, but a slight difference in the way the pickup/preamp hears the overtones.

Having never been an EMG user before, i'm really impressed with the quietness of them and their sustain. Also their ability to really "hear" the string. Picking softly on a clean channel gives you that Metallica "Enter Sandman" tone instantly. With gain, they're quite articulate and brutal. No surprise, really.


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## st2012 (Sep 7, 2008)

Great diagram! Helpful as always Darren


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## decoy205 (Sep 8, 2008)

This is great. i never knew about this mod before this forum thanks for the information.


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## 7deadlysins666 (Sep 9, 2008)

I just did this to my Schecter C7 which has Duncan Designed active pickups.....you CAN do it with *Duncan Designe*d active humbuckers. Just to let everyone know. Sounds amazing.



eleven59 said:


> Ah yeah, valid point. I think if I end up trying this with my Hellraiser, I'll be doing it the way I suggested, with the two batteries taped together and taped into the back of the guitar, as it only has room for one battery in its battery compartment



I have this problem too. I THINK what im going to do after I tape off the joints I just soldered (can't find my damn electrical tape!!) Im going to rout the wires for the original battery connector back into the control cavity, and just have both batteries in there. That way you don't have to worry about the batteries falling off the back of the guitar etc. I can't seem to find my camera's charger so I can't do a tutorial on it but if you'd like I'll tell you how it works.


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## Groff (Sep 11, 2008)

I have a question.

I'm trying to get a Schecter Loomis hardtail for christmas, and I'm curious to see what the 18v mod can do. I plan on making the reversible harness as you posted as that is VERY easy to do. But I had a thought. Is there ANY way to hook up an on-on toggle switch to the harness so that you can SWITCH between 18v and 9v?


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## angus (Sep 23, 2008)

Of course. 18V power into one input, 9V power into the other input, center output is power out. I actually usually do it with the ground circuit (18V's ground is input 1, 9V ground is input 2, output is chosen ground) as it's technically safer and easier on the circuit, but it really doesn't matter for these currents. Most people do power, hence why I mentioned it first.


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## Metal Ken (Sep 27, 2008)

TheMissing said:


> I have a question.
> 
> I'm trying to get a Schecter Loomis hardtail for christmas, and I'm curious to see what the 18v mod can do. I plan on making the reversible harness as you posted as that is VERY easy to do. But I had a thought. Is there ANY way to hook up an on-on toggle switch to the harness so that you can SWITCH between 18v and 9v?



I was just looking at this thread as i just did the mod to the OFR loomis. If you get solid plastic battery clips, you'll have to mount both batteries in the control cavity (It takes up just a hair too much room to use the main battery compartment using this mod-- Unless you splice off the connector from the stock batteries and soldier the new jack on)

That said, i'm sure the switch is possible, but on the loomis i barely noticed any difference between the two. I sat there and A/B'ed them for about twenty minutes. Its true what darren said about some more dynamics, but the basic tone of the pickup, to my ears, is unchanged. i was just using a practice amp, as my cabinet for my Single Rec is at the band practice space, but in the end, i cant justify spending another 3 dollars to buy another 9 volt so i dont have to use my hellraiser's battery. it really doesnt make too much a difference to me.


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## mmotorsport (Oct 1, 2008)

I just did this mod on my new ec-1000 with dual 81's. I love what it did for the bridge pickup but the neck pickup has seemed to loose all of its jazzy tone. I can barely tell the difference when i switch between the two. any one ever had this happen


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## andreeee (Oct 2, 2008)

mmotorsport said:


> new ec-1000 with dual 81's.


 
i thought the ones with emgs came with a 60 in the neck?


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## mmotorsport (Oct 2, 2008)

the models now do come with 81/60...........the earlier ones came with dual 81's


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## soldierkahn (Oct 3, 2008)

it should be possible to run your bridge pup off of 18v and then wire your neck pup to run off of 9v. i wouldnt dare try to make a diagram for yall, considerin i dont have the right crayons lol

but it should be possible


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## Neil (Oct 22, 2008)

Hey can someone confirm whether this wiring diagram will work.

Its using a push pull pot (DPDT switch) in the middle of the diagram, the advantage of which in 9V the batteries drain equally.







Cheers


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## darren (Mar 25, 2009)

eleven59 said:


> Like this:



I tried this the other day, and 9v battery clips are not wide enough to make the connection between the two batteries placed side-by-side in this fashion. At least not Duracells. I don't know if the dimensions of other 9v batteries may vary a bit, but the terminals were too far apart to connect them like this. I suspect that's partly by design.


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## Prostheta (May 20, 2009)

+1 on the tutorial and the variations. I think that your mileage will vary depending on what you're looking for....the compression in a 9v circuit can be useful just as much as higher dynamic range. My 81/81 ESP Explorer clone build sounds undefined and far too compressed in the bridge position at the moment, so i'm going to see how a tapped 18v bridge and 9v neck compare to a 18v for both versus the current 9v.

I like to roll the tone off for the neck position when soloing, so compression lends itself nicely to that pickup position. I think I know what the result will be, so let's see how it is in practice....


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## xtrustisyoursx (Jul 4, 2009)

Just did this exact thing to my Interceptor with 707s, and I love it. Really opened up the pickups. It kept and enhanced the stuff I liked about EMGs but added the headroom and open sound of passives.


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## Galius (Oct 28, 2009)

Just made my harness, just need to wait until practice to try it on my Intrepid


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## 8string (Dec 8, 2009)

Wonder if this mod will work on my ibanez sdgr 5-string.... active pups, but i don't have any details about them


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## Prostheta (Dec 8, 2009)

Difficult to say. Ibanez pickups are more likely to be an active *circuit* rather than being active *pickups*, despite the distinction being academic in most cases.

EMG actives have the preamp onboard the pickup potted into the epoxy, and these can usually run on 27v supplies (excessive!) but the specific circuit Ibanez use on your bass might not be too happy with higher supply voltages and might fail in the long term. It'll void your warranty for sure!

Find out more about it first....!


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## 8string (Dec 8, 2009)

warranty is long gone anyway, and i've been thinking about getting emg's anyway. I just put in the order


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## Prostheta (Dec 9, 2009)

Want to sell me your pickups? ;-)


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## 8string (Dec 9, 2009)

Sure


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## Prostheta (Dec 9, 2009)

PM me the details of the bass model, what you want for them and i'll have a look at it all. I might be building another bass soon, or I might be GASing :-\
TIA


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## Fred (Dec 9, 2009)

Did this a while back to my Kramer as a temporary measure before I install some other pickups in it (got a Tonezone for the bridge position and I'm going to reconnect the hot rails pups in middle and neck positions to see what they sound like), and it's insanely easy and totally worthwhile. I found the effects far more noticeable with clean tones than distorted ones, perhaps unsurprisingly, but it's worth it for that alone!


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## Fzau (Mar 8, 2010)

Here we go, I opened up my Loomis' control cavity since the battery was dying and I'd like to do the 18V mod 

Problem is I have no idea of what I need(/to do)..
There is not enough room in the battery compartment so I guess I have to put both batteries in the control cavity, right?
If so, do I just cut the original clip in the battery compartment and solder a new one on in the control cavity?
Or can I leave one battery in the battery compartment and one in the control cavity?

Also, is it necessary to tape the batteries with copper tape?
And could I do this over the electronics in the cavity as well or will it not change anything?

I'm a retard when it comes to electronics, so an additional detailed sketch would be nice


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## darren (Mar 8, 2010)

Yes, you can put one battery in the control cavity and leave the other in the battery compartment. 

No, you don't wrap the batteries in copper tape. My illustration shows Duracell batteries.

If you're a retard when it comes to electronics, i would suggest taking your guitar to someone less retarded.


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## Fzau (Mar 8, 2010)

darren said:


> Yes, you can put one battery in the control cavity and leave the other in the battery compartment.
> 
> No, you don't wrap the batteries in copper tape. My illustration shows Duracell batteries.
> 
> If you're a retard when it comes to electronics, i would suggest taking your guitar to someone less retarded.


 
I will 
Thanks a lot man


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## Slide (May 13, 2010)

I did the 9V parallel / 18V series mod to my Hellraiser C-7 a while back. Before that that I just had 18V. I used a mini toggle switch, drilled a hole for it just next to the bridge volume (so that the switch sits right above the knob where my hand usually doesn't touch it). This was just what I needed - more compression on tight riffing with 9V, but also more dynamics with open chords with 18V etc. Well, you get the picture.


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## DUY1337GUITAR (Aug 8, 2010)

Did this on my Schecter Damien Elite 7... I followed the exact diagram, everything was perfect, I even triple checked... But the mod killed my pickups. I tried swapping back to 9V, and nothing.


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## Purist (Aug 14, 2010)

DUY1337GUITAR said:


> Did this on my Schecter Damien Elite 7... I followed the exact diagram, everything was perfect, I even triple checked... But the mod killed my pickups. I tried swapping back to 9V, and nothing.



The mod DID NOT kill your pickups, you probably did something else to damage them...I suggest that you check your wiring(not the battery harness but the actual pickup circuitry) Several people including myself have done the mod successfully. Check out the dudes post above you, he even tried series and parallel 18v mods. I've also seen people try 27v mods(google it), although it didn't provide substantial results, it DID NOT fry their emg preamps. Please refrain on posting such comments, unless you have reproduced the same results with said mod more the ONCE. The 18v mod is great and i hope your comment doesn't turn people away from it. TRY IT PEOPLE, its GREAT!


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## DUY1337GUITAR (Aug 14, 2010)

Purist said:


> The mod DID NOT kill your pickups, you probably did something else to damage them...I suggest that you check your wiring(not the battery harness but the actual pickup circuitry) Several people including myself have done the mod successfully. Check out the dudes post above you, he even tried series and parallel 18v mods. I've also seen people try 27v mods(google it), although it didn't provide substantial results, it DID NOT fry their emg preamps. Please refrain on posting such comments, unless you have reproduced the same results with said mod more the ONCE. The 18v mod is great and i hope your comment doesn't turn people away from it. TRY IT PEOPLE, its GREAT!



Oh, I wasnt trying to scare ppl away from the mod, I know it's great. I'm not saying the mod doesnt work at all, I'm just saying ppl should be careful, I've found some forum posters saying it happened to them, too. 

I know there is nothing wrong with my set up. I bought a new EMG 707 and put it in the bridge position (Guitar Center was doing a $20 off $100 sale). It worked fine, which proves that my previous pickups were actually fried, nothing was wrong with the wiring. 

I think what actually happened was that I probably didn't pay attention to the two battery snaps while I was placing the two batteries and the snaps probably touched in reverse polarity. EMGs dont fry at -9V, since they are reverse-polarity protected at that level. -18V will fry it though, EMG said it themselves. So I'm pretty sure I was really unlucky to have the snaps touch in reverse somehow (=__=)

Oh well, I'm just gonna move on, not gonna waste my time brooding on it. But I am happy that I have the EMG 707 in the bridge, I actually LOVE it. Definitely prefer this pickup than the EMG 81-7.

And of course, the 18V is a great mod, definitely a must-try


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## maxoom (Sep 6, 2010)

I was already to try this bought clips and all as I have two EMG guitars but decided I prefer the thicker fuller tone of 9 V.So I just keeping mine as is.That spread out sound is not what most EMG players are after anyway or they would not have EMG`s.


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## Jedi Pirate (Sep 6, 2010)

I have a small question, I have those 9v battery connectors http://www.industrial-enclosures.com...-Anschluss.JPG , and i was just wondering if i can just cut the wires leading into the battery compartment because it's those small metal plate type of connector for the battery,(or just unsolder them) then just twist on one of the connectors right? and then just work from there


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## Mn3mic (Sep 13, 2010)

Can you guys post some more sound clips? I would really like to hear some differences and improvements in the sound.

It would be great if someone had some before/after sound clips on the same sound setup.

And thx for the great tutorial, I think I'll give this a shot soon...


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## techdeth (Sep 24, 2010)

So easy and so worth it. Thank you very much.


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## darren (Sep 24, 2010)

Mn3mic said:


> Can you guys post some more sound clips? I would really like to hear some differences and improvements in the sound.
> 
> It would be great if someone had some before/after sound clips on the same sound setup.
> 
> And thx for the great tutorial, I think I'll give this a shot soon...



If you go back to the first page, you'll see that i did post a sound clip in my second or third post.


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## sh4z (Oct 10, 2010)

Hi Guys,

I have been discussing with a friend of mine about making up a circuit for switching between batteries 9v and 18v.

Essentially the switch will be 4 way with the following options. 






1. 2 x 9v in Series - 18v mod.
2. 2 x 9v in Parallel; 9v.
3. 1st Battery 9v.
4. 2nd Battery 9v.


Any ideas


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## sh4z (Feb 6, 2011)

I guess thats a no.


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## stevo1 (Feb 20, 2011)

sh4z said:


> Hi Guys,
> 
> I have been discussing with a friend of mine about making up a circuit for switching between batteries 9v and 18v.
> 
> ...



there is really no point for this. you'll only have two sounds. the 9v regular sound and the 18v sound. having two 9v batteries wired in parallel would only increase battery life, and being able to switch from one battery to another is pretty pointless. i would suggest only wiring two of the option mentioned. the regular 9v only 1 and the 18v series thing. but hey. not my choice.


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## sh4z (Mar 9, 2011)

Thanks for the input... any idea how to actually wire it up though? I was hoping to get like a schematic or something.


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## stevo1 (Mar 14, 2011)

sh4z said:


> Thanks for the input... any idea how to actually wire it up though? I was hoping to get like a schematic or something.



i really dont know how to wire the 9v and 18v mod to a toggle switch to change whenever. i know someone has done it, but i havent done it myself. i just stick with th 18v mod. feel free to search for it though! it might even be in this thread


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## TRENCHLORD (Apr 29, 2011)

I tried 18v mod and I preferred the 9v sound. Not a huge difference either way, but definetly noticable. The thing is, when I roll the volume back just a TINY bit when in 9v mode, it sounds almost and feels almost like 18v mod with volume max. I do think the toggle option is perfect solution though. Variety is always a great option.


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## Gothical (Apr 30, 2011)

Just did the 18v mod in my RGA8 with emg 808 and I can safely say that I really prefer the 18v mod. The bass was definitely much more punchier and the highs were more pronounced. By the way Im tuned EBEADGBE so I needed more bass for the E but the pickups didnt seem to handle that too well but now I just couldnt be more happier. Now how the hell do i get rid of the damn buzz


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## stevo1 (May 5, 2011)

TRENCHLORD said:


> I tried 18v mod and I preferred the 9v sound. Not a huge difference either way, but definetly noticable. The thing is, when I roll the volume back just a TINY bit when in 9v mode, it sounds almost and feels almost like 18v mod with volume max. I do think the toggle option is perfect solution though. Variety is always a great option.


what pickups are you using?


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## TRENCHLORD (May 5, 2011)

81/60 combo 9v for me. Although everyone's setup is different, and the string setup(tension/tuning) even makes a difference what will work best.


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## Jaqen (Aug 30, 2011)

In my 707 there was a little more dynamics in clean sounds, distortion sounds are already compressed on their own, so the difference is minimal


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## Chris Migdalski (Oct 23, 2011)

I have been using an 18Volt mod in my Ibanez RG2228 8 string for about a year now and have been very happy with it actually opening up the characteristics of the EMG's tone but I have an idea.....If I wanted to install a push pull volume knob as a switch to say RUN the 18 volt mod as the knob is normally pushed in and then just 9 volts pulled out ...has anybody tried this seems easy enough...just curious on opinions


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## Jesse Zuretti (Oct 31, 2011)

Awesome. Doing this at some point this week!


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## sonicwarrior (Jun 3, 2013)

sh4z said:


> Thanks for the input... any idea how to actually wire it up though? I was hoping to get like a schematic or something.



I made a graphic explanation although it doesn't look as good as the one in the OP as I used LibreOffice Draw.

As the picture says I've not tested it but if you look at a DPDT on-on switch datasheet you can check this yourself: Switch position 1 connects the pins 1 & 2 plus 4 & 5. As pin 4 is connected to the plus pole of the first battery an pin 5 to the minus pole of the second battery and there is nothing connected to pin 1 this is the only connection and equals a serial connection of the batteries which means you get the 18 V.
Switch position 2 connects the pins 2 & 3 plus 5 & 6. Pin 2 is connected to plus on battery no. 2 and pin 3 to plus on battery no. 1. Pin 5 is connected to minus on battery no. 2 and pin 6 to minus on battery no. 1. So this is the parallel aka 9 V mode to safe battery life.

Check with a DMM before connecting to the pickups.
Don't have one? Get one!  A cheap one will be sufficient.


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