Long distance guitar cable...

[Professor]

So I need the help of some guitarists out there. I want to know how long you can run a guitar cable without losing signal, and if there is a way to juice the signal to run longer before hitting a DI-box.

I have a pair of Avalon U5 direct boxes rackmounted in the control room and I ran 18gauge twisted pair, shielded wire from the studio to the control room to use as instrument lines. The cabling is about 10-15 feet of instrument cable to the wall, about 100-feet through the conduit to the control room patch panel and about 5-feet from the patch panel to the DI box input.

I have run bass both from electrics and uprights through this system without any problem but I had some trouble with an electric guitar that lost alot of its high-end on the trip. I've not tried any other guitars, acoustic or electric, but I would like to know if anyone has ever driven a really long run like that from a guitar. I would like to keep the DI boxes racked for their safety and security, and for ease of access.

So, has anybody done these kinds of lengths before, or does anyone know of a guitar 'line-driver' that could get the signal to the DI? Or was this just a fluke that I will only run into on the odd one or two old axes and that I needn't worry about. It does work on bass and most everyone has liked the bass sounds so far - except for the occasional bass player who was too used to the sound of his crappy bar band amp. But then I was losing the high frequency signals, not the lows.

Thanks in advance.

-Jeremy

[Shawn Simmons]

IMHO, you need the DI's to be out in the room with the musicians. An instument level signal will degrade very quickly the longer you run it. I NEVER run a guitar line longer than say 10 feet and even that is a lot. Get your direct boxes out of the racks and into the room close to the instruments.

Another thing to try to taking a preamp and putting it out in the room so that you can get the signal up to line level and then drive that over a long distance. I do this all the time.

Or just use your mics and no your DI's and you'll be fine.

Shawn

[mrhawkinson]

100 feet is definitely too long for an electric guitar. You could try buffering the guitar by running a short line to a pedal with high input impedance and then the long run after that, but a better bet would be to get the preamp/DI into the room and run a balanced mic or line signal to the control room.

-p

[Professor]

There is no question that the best way to do this would be to put the DI in the studio room. Ideally the guitarist will care enough about his sound to have a nice sounding amp without tons of electrical hum and I could just run a microphone on that. But I would prefer not to toss the U5 out on the floor with a bunch of students in the studio. And I also have instrument inputs on other mic preamps as many folks do. I don't want to unrack the Groove Tubes ViPre to use it as a DI, it's around 40 pounds and takes two people to unrack - but I would love to use its DI input.
So the question isn't should I run a 150 foot guitar cable - it is what do I need to do to preserve the sound over a 150 foot cable. Surely the live sound guys have run into this on big tours. I like the pedal idea, perhaps a visit to the Boss website is in order.

-Jeremy

[kayagum]

http://www.sweetwater.com/insync/04/23/2002/
http://www.sweetwater.com/insync/05/10/2002/

I can vouch for the VHT Valvulator option.

[AGCurry]

It depends on the capacitance of the cable, but 18 feet is the commonly-accepted limit on length of a high-impedance guitar cord. More than that and the high-frequency loss can be noticed. Sorry, dude.

[mrhawkinson]

Jeremy-

You could use a relatively cheap and sturdy DI to run mic level to the fancier inputs you want to use. Or you could play guitar in the control room and send the signal 150' to an amp in the tracking room -- if you're not recording the amp it won't matter if it's hummy or rolled off. Or you could try a wireless. Any of these would work better than trying to send an unbalanced signal 150 feet.

-p

[Professor]

Thanks for the responses all, I do appreciate the help. Honestly I'm a bit surprised the question doesn't come up more often given the overwhelming number of outboard mic-preamps being sold, each with their attractive looking DI connection on the front. By the time one has a few preamps in the rack the DI connections are piling up and remaining unused if the cable can't be extended.
The VHT piece is very much along the lines of what I was looking for - now I just need to find a price, though I'm sure it is high.
Not to leave all of the searching to others, I did some hunting myself and found some possibilities. Honestly I am a bit surprised that ReAmp doesn't have something considering that the ability to record DI feeds really allows the ReAmp to be used.
I did find that Little Labs has this huge guitar distribution box which includes a long length line-driver output on the back side, though the box runs 1100 list. http://www.littlelabs.com/pcp.html I'll be contacting them to see what they have built into the line driver and to see if they will be offering it in a stand-alone box.
I also found these pieces from Pick-Up the World in Colorado and I've already contacted them about the length issue which they say is no problem for their box. http://www.pick-uptheworld.com/preamps.htm This is much more the size and cost I had in mind for the project. I wouldn't mind a transformer isolation, but their mono line driver should do the trick.
I'll also check with some transformer companies and such to see what I can find. I suppose that with a couple of drivers around and a couple re-amps, I can work this exactly the way I was hoping. I'll keep everyone abreast of the results.

-Jeremy

[jajjguy]

My question about the Valvulator is, doesn't it change the way your stompboxes/amp/DI sound? Since it's changing the impedance of your guitar signal, i'd expect that would make it interact differently with everything that comes after it. And wouldn't it eliminate the point of a DI anyway?

Professor, in my (limited) experience, when a guitarist uses a DI, they're in the control room, which might explain why this issue hasn't come up much.

[NewYorkDave]

The usual shielded, twisted-pair for studio use has way too much capacitance for a high-impedance signal like that from an electric guitar. Your typical Belden 8451 or similar type is 30pF or more per foot. Trying to run an unbuffered, high-impedance signal over a long line is usually a losing proposition; however, you might get acceptable results with an AES/EBU compatible shielded twisted pair (10pF per foot typical) or even video coax. The former is similar in composition to a "regular" shielded twisted pair, but much thicker due to more dielectric used between the conductors. That's what gives it lower capacitance.

[soundguy]

I have a little labs pcp and can not live without the thing. I usually use a zvex sho for driving a guitar from the control room into the amp room, which happens just about every day. Fullclone makes a line amp as well, the zvex is the one to get for a variety of reasons...

dave

[Professor]

Conveniently the same microphone patch panel that has the instrument lines also has AES/EBU lines and RG6 video lines pulled to it as well, and I had considered trying the video lines also, but naturally I want to see if I can make the existing setup work before pulling more wire through the conduits.
I will have to check out the zvex and the fullclone pieces as well. And as I mentioned the Pick-up The World guys said that is exactly why they have their line driver. I still need to check out the transformer companies.
Thank you all again.

-Jeremy