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I'd like a clear answer, please: DO DI BOXES DIVIDE YOUR SIGNAL Direct Injection & Re-amp Boxes
Old 31st August 2011
  #1
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Cursed Lemon's Avatar
I'd like a clear answer, please: DO DI BOXES DIVIDE YOUR SIGNAL

If you are using the thru-put and the balanced output of a DI unit, is your signal degraded/lowered in amplitude?

If not, how is this avoided?
Old 31st August 2011
  #2
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Seb RIOU's Avatar
 

No DI boxes don't divide or degrade your signal.
It adapts it to different interfaces.

The "thru" output is a parrallel circuit of the "normal" input, properly buffered you lose absolutely no "amplitude"( in fact voltage ) of your input signal.

BUT , if you compare this signal of the balanced output, you sure find a difference : Input is Instrument level, High Impedance (that's what you get with the "Thru" out, which is in fact, an In, got me bro ?)
Output is Low impedance, Mic level.

The two are separated by an active circuit, or a transformer in case of Passive DI's.

The problem if you want to use the "thru" output as a Line or Mic signal, is not so much the level , but Impedance mismatch. That out is dedicated to an instrument device, such as a guitar Amp, or stompbox.


Don't know if I'm clear, though ..anyway
Old 31st August 2011
  #3
There's no single answer because there are different kinds of direct boxes.

Suffice it to say, however, that however one feels about the changes, if you run your signal through an active circuit or a transformer, that signal will be changed to some, perhaps very small (perhaps not so small) degree.

Also, with regard to splitting signal, signal level, and impedance with regard to passive boxes, it should be clear that you don't get something for nothing. If you split a signal, the amount of actual energy being transmitted will be split between the outputs -- and some energy will end up converted to other energy forms, primarily heat. Whether that will make a significant difference depends on the devices on either side of the DB.
Old 31st August 2011
  #4
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I do know that DIs will color the sound to a miniscule degree. But if plug my guitar straight into the DI on my Mbox, check the average levels, then I plug my guitar into a DI box and check the level again while going out the thru-put, am I going to be getting the same output level?

My reason for asking is because amplifiers are obviously level-dependent in regards to their coloration and overdrive.
Old 31st August 2011
  #5
Registered User
With a passive transformer DI, using the Thru and the normal balanced output together will definately place a greater load on the input. Probably not a problem if you are running active pups which are already buffered - but I AVOID if using passive pups.

If using an active box, these seperate outputs may (or may not) be buffered and it should be ok to use them (or not).

This is why some people suggest passive DI for active pups, and active DI for passive pups. Personally - I like to use passive with passive (Radial JDI) but I never use the Thru from the DI - I use a spare output from my preamp, and then use a Reamp box to knock that down to guitar level. I'm now hearing a different tone, but essentially the same tone I will get if I Reamp later. I consider it as a high class booster and make it part of the solution instead of a problem.

Look at the circuit for your particular DI (it's often published in a simplified flow chart diagram).

Or use your ears. If it works and you are happy, just do it.
Old 31st August 2011
  #6
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When you say "buffered," what do you mean precisely?

I'm mostly electronics-illiterate, mind you.
Old 31st August 2011
  #7
Registered User
A electronic 'buffer' is basically any audio amplifier stage - which has the effect of making the input more or less independant of the output.

Look at it this way: an audio source has limited Power. Power (milliWatts in this case) is the factor of Volts and Amps. Especially with passive pickups or microphones, the available power is very small.

If you place a greater load on a small power source, it drags it down or can even strangle it completely. You can compare this to a garden hose - with the nozzel blocked with your finger, pressure is as high as it can be. As you release your finger, the water can flow (current) - but the more you allow the water to flow, the more pressure you lose. This is why you can squirt a smaller amount of water a greater distance, or just let the water fall out with little pressure.

Energy is conserved - so you can't gain one without losing the other.

However - with an Amplifier stage, we are adding Energy from a power supply. We can add as much as we like (depends on the size and quality of the power supply).

That's basically 'buffering' ... typically would refer to a Unity gain amp stage. Unity gain means Voltage in = Voltage out, but the reason for having an Unity gain amp is basically to preserve current/amps.
Old 31st August 2011
  #8
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This is one of those questions that makes perfect sense theoretically, but is a non-issue in practice. It is quite easy to listen to your signal directly into your amp, and then from a DI's "thru" into your amp. If you are happy with the latter, it's a non issue. Adding 5' of patch chord to a hiZ signal will probably make more of a tonal difference than using a proper DI's thru output.
Old 31st August 2011
  #9
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Actually that's a good explanation of what buffering is, but not why it has such a huge effect. Your guitar pickups form a resonant circuit, a little like a wah, between the pickups, the controls and the input to the next thing along the way. If the input impedance (or resistance) of the next stage is too low, the resonant peak will be dragged down and your guitar will sound dull or muffled. You can prevent this with a buffer before you split the signal, so that the guitar only sees the one, high impedance input. If you plug guitar into DI, then out from DI to amp, the guitar is seeing two output devices and the impedance is 1/2. It's also important to realize that studio gear often does well with an input impedance of 500 kohms, but guitars are happier at 1 megohm, so a DI that's perfectly fine for a keyboard may make a guitar sound dull and lifeless. That's why many mixers/interfaces have a special input for guitar/bass.
Old 31st August 2011
  #10
Registered User
Basically saying the same thing with different words.

The English word Impede means to put up an obstruction, or restriction. When we are talking about High or Low Impedance, we are talking about a high "obstruction" or a low "obstruction" to the flow of electrical current.

Very much like putting your finger over a hose.

If we connect two loads onto a source, that's basically adding another path, or effectively removing some of the obstruction. Think about thousands of people trying to get off a crowded motorway - more exits make it easier for the traffic flow.

Current is more important for bass.
Voltage is more important for highs.

So different impedance loads can affect the frequency response.

The musical effect has to be judged by your ears. If it sounds good, it's good.
Old 31st August 2011
  #11
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Quote:
Originally Posted by Kiwi View Post
I use a spare output from my preamp, and then use a Reamp box to knock that down to guitar level.
Coincidence! I'm doing the same thing with my GTQ2 pre and Little Labs RedEye Phantom 3D.
Old 1st September 2011
  #12
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Seb RIOU's Avatar
 

Quote:
Originally Posted by mtl777 View Post
Coincidence! I'm doing the same thing with my GTQ2 pre and Little Labs RedEye Phantom 3D.
As high is my opinion of Jonathan Little's and Aurora gear, I'd be more concerned for the integrity of my signal to go HiZ/LoZ/HiZ, than to split it via my JDI
Old 1st September 2011
  #13
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The beauty of hi/lo/hi is that you're hearing how the reamp will sound
Old 1st September 2011
  #14
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Quote:
Originally Posted by Seb RIOU View Post
As high is my opinion of Jonathan Little's and Aurora gear, I'd be more concerned for the integrity of my signal to go HiZ/LoZ/HiZ, than to split it via my JDI
Quote:
Originally Posted by wxyz View Post
The beauty of hi/lo/hi is that you're hearing how the reamp will sound
+1 And I also love the sound of the GTQ2 DI. It imparts a nice flavor to the amp'd sound that I wouldn't get if I went straight to the amp. In the end, what sounds good to me is all that matters.
Old 2nd September 2011
  #15
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Fair enough
Old 2nd September 2011
  #16
A quality passive DI like the Jensen transformer will present a 180 k load on the pasive pickups. That will damp the tops a bit. It's the parallel load that matters. Add to that the 250 k load of a fender volume pot or a 500k pot for Gibsons and that lowers further.

Active instruments work great into those passive DI boxes. Active DI designs usually have higher input impedance, usually 1 meg ohms or higher. Still, feeding a tele with 1 meg volume pots will cut that load by 1/2 and present a 500 k ohm input impedance, all of these loads affect the pickup's frequency response and the amount of damping of the pickup's resonant peak.
Old 4th November 2011
  #17
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Stefbossa's Avatar
 

Quote:
Originally Posted by Jim Williams View Post
A quality passive DI like the Jensen transformer will present a 180 k load on the pasive pickups. That will damp the tops a bit. It's the parallel load that matters. Add to that the 250 k load of a fender volume pot or a 500k pot for Gibsons and that lowers further.

Active instruments work great into those passive DI boxes. Active DI designs usually have higher input impedance, usually 1 meg ohms or higher. Still, feeding a tele with 1 meg volume pots will cut that load by 1/2 and present a 500 k ohm input impedance, all of these loads affect the pickup's frequency response and the amount of damping of the pickup's resonant peak.
Great info!

Jim, what do you recommand to use for DI with passive pickup instruments since there is a lost of high frequencies with classic passive DIs (Radial, etc)?
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