Guitar Amp to DI cable question?

Douglas R. Allen

Douglas R. Allen

Sophomore
Jan 11, 2011
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15
18
Maine USA
I working with a different band tonight. The guitar player says he uses a DI box with a Pad to take his speaker level and convert it to XLR mic level. I have no problem with doing it but my question is this.
What is the correct cable to use between the amp and DI? The amp has a 1/4 speaker out. The amp is also loaded to a cabinet but he wants to use the DI as well as a microphone for recording.
Should it be an unbalanced 1/4 to 1/4 shielded cable? Or a regular speaker cable.
I realize because of the DI impedance load a high power speaker cable is not needed but which would be correct?
Maybe it won't matter at all?

Thanks for any input.
Douglas R. Allen
 
Re: Guitar Amp to DI cable question?

you're right, it won't matter. the signal level is hot enough that it doesn't really need to be shielded, and the load that the DI presents is low enough that it doesn't need to be heavy gauge..

Jason
 
Re: Guitar Amp to DI cable question?

In general speaker cords are twisted pair and not shielded. An amplifier that is not happy with a capacitive load may not like a long shielded cable so that is one consideration.

Some studio DB actually load the amp, but live boxes generally don't so wire gauge is not an issue.

JR
 
Re: Guitar Amp to DI cable question?

Show went ok.

He had his own 1/4 - 1/4 shielded cable.
Signal was not overly hot. About average input.
I did try it live and ended up putting a 7k and above high cut as well as a 80 hz low cut.
On clean patches I used it the most.
Compared to the 609 on the cabinet I thought it was not too bad. Lacked "something" but will have to listen to the tracks later to see.

Thanks;

Douglas R. Allen
 
Re: Guitar Amp to DI cable question?

Guitar amp speakers and cabinets are far from attempting to linearly reproduce the amp output voltages they receive, so a flat DI from that point will lose most of that cabinet/driver's intentional designed in voicing.

I have seen dedicated DI for this application that included some simple EQ to tweak the dry DI signal to be a somewhat better representation of the amp sound. Guitar amps are part of the musician's sound so flat DI is less realistic than putting the amp in an isolation box or room offstage and micing that.

JR
 
Re: Guitar Amp to DI cable question?

In most any tube amp (Fender, etc) the speaker outputs are designed for a specific load. Running one output to the speaker and the other to the DI is a bad idea as the amp will not see the DI load, it would look like an open, but it is now running on a different transformer tap because they use switching jacks on the back. They use different taps for 8 ohm, 4 ohm, 16 ohm, etc. None of this would matter much with a solid state amp. I have also, when I was 19, melted a guitar cable that was used on a bass rig between the DI and amp. That head apparently didn't like shieded 22gauge. Live and learn. There is no chance of picking up buzz from the use of a speaker cable in this situation. Never had an issue just going amp to di to speaker (using Countryman, BSS, and Whirlwind) using a speaker cable. Be sure to use the PAD on the DI for your console feed.

I just thought it might be important to note the amp itself may not be happy in this arrangement. Not saying it'll smoke on your gig though.
 
Re: Guitar Amp to DI cable question?

John Roberts said:
Guitar amp speakers and cabinets are far from attempting to linearly reproduce the amp output voltages they receive, so a flat DI from that point will lose most of that cabinet/driver's intentional designed in voicing.

I have seen dedicated DI for this application that included some simple EQ to tweak the dry DI signal to be a somewhat better representation of the amp sound. Guitar amps are part of the musician's sound so flat DI is less realistic than putting the amp in an isolation box or room offstage and micing that.

JR
Click to expand...

"Like"

And "Sansamp" might be the word you were looking for (at least back in the day) although I think Line 6 has made a whole line of amp emulators too and may make a DI.
 
Re: Guitar Amp to DI cable question?

hbrilljr said:
"Like"

And "Sansamp" might be the word you were looking for (at least back in the day) although I think Line 6 has made a whole line of amp emulators too and may make a DI.
Click to expand...

No I know the brand I was thinking about, but it's boring to keep saying Peavey made one of these too.... :-) But yeah, peavey made one of those and that's where I saw it.

JR
 
Re: Guitar Amp to DI cable question?

John Roberts said:
No I know the brand I was thinking about, but it's boring to keep saying Peavey made one of these too.... :-) But yeah, peavey made one of those and that's where I saw it.

JR
Click to expand...

Peavey called theirs EDI if IIRC. I had one back in the 80's, worked ok.
 
Re: Guitar Amp to DI cable question?

Yup sounds about right,, there was an active DI I designed called the EDB (IIRC) and a passive transformer with EQ DI called the EDI (equalized direct injection ?) or something like that. The transformer in the EDI was small, sized for mic level signal output after a resistor pad on it's input... My EDB (electronic direct box) with no transformer at all, was more of a studio box designed for high impedance wide bandwidth instrument feeds for AMR recording products division, but a Peavey version got sold and used in live SR, and IIRC i tweaked the design a little (the amount of pad on the output) to be a little more happy in live SR applications based on feedback from users. But this was all so long ago I don't even recall the exact tweak I made.

JR
 
Re: Guitar Amp to DI cable question?

Bennett Prescott said:
Just don't run the signal for the speaker through the DI! Split it, or put the DI after the speaker.
Click to expand...

Why?

My experience is very limited so any info on why one way is better than another is appreciated.

fwiw,The one time I used a DI pushed by an amps output was a guy who put his H & K Redbox, between his amp and speaker and insisted I use that.
Luckily for me, it sounded pretty good.
 
Re: Guitar Amp to DI cable question?

Steve Hurt said:
Why?

My experience is very limited so any info on why one way is better than another is appreciated.

fwiw,The one time I used a DI pushed by an amps output was a guy who put his H & K Redbox, between his amp and speaker and insisted I use that.
Luckily for me, it sounded pretty good.
Click to expand...
1/4" plugs and jacks and the resultant connection between then is a pretty lousy current conductor.

So by adding the extra 2 connections (4 if you count the tip and the sleeve) between the amp and the loudspeaker-there is possible loss.

With the DI after the amp-there is very (call it none) current flowing into the connections between the DI and the loudspeaker-due to the high impedance of the DI box.
 
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Re: Guitar Amp to DI cable question?

I understand the 1/4" being a crummy connection. Makes sense.


When you say
... (call it none) current ..
Click to expand...
wouldn't than mean much lower output at the speaker?
(like a power soak)
 
Re: Guitar Amp to DI cable question?

Steve Hurt said:
I understand the 1/4" being a crummy connection. Makes sense.


When you say wouldn't than mean much lower output at the speaker?
(like a power soak)
Click to expand...

I believe his point is that the loudspeakers will be drawing amperes and the DB milliamps. In general running the higher current path through an extra set of 1/4" connections is providing another opportunity for a bad connection. Even an apparently working speaker level connection can have enough series resistance to heat up and degrade further over time.

FWIW, there are dedicated high current 1/4" speaker jacks with dual tip contacts and higher contact pressure to deliver lower contact resistance more reliably. Many 1/4" jacks designed for signal level current, are not as robust and may be unreliable passing high current.

JR
 
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Re: Guitar Amp to DI cable question?

Reliability is important and that sounds like the preferred way to do it (separate 1/4" jacks powering each)

Just trying to understand if there was a sonic difference (assuming everything is working correctly at the moment)
 
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