D.I. Box ?

ReWired · Jun 24, 2004, 04:00 PM

Probably this question is too stupid...if so, please, excuse me

I don't know what exactly is this hardware D.I. Box and what it does....
Anyway, my question is:
Can this D.I. Box be emulated using the present kX DSP effects? And if yes - which ones will do the job?
Thanks in advance!

**dj_stick** · Jun 24, 2004, 10:39 PM

a D.I. box converts the low signal from a guitar to a line level source for use with mixers and computers. Doing so in the DSP would cause a lot of noise - for about $25US you can pick up a decent behringer one

ReWired · Jun 24, 2004, 11:37 PM

So, this is a preamp, with some sort of noise reduction?

**dj_stick** · Jun 25, 2004, 01:30 AM

it is a pre-amp - but th preamp on the card is very noisy

Tiger M · Jun 25, 2004, 06:21 AM

D.I. Box = Direct Input Box.
They're good for the high input impendance and the balanced low output impendance they produce.
A good cheap pre-amp solution (espetially with the kX DSP where you have full control over the sound, that is you don't need any pre-amp filtering).

NOTE: Some need phantom power.

TravelRec. · Jun 25, 2004, 06:27 AM

Hi!

Sorry guys, but a D.I. box is some different from what you said: it is only a cable converter, not a level-shifter nor a preamp. It can be passive (with a transformer) or active (with OP-Amps). A D.I. box is used to make unsymmetrical signals (just from guitar or mic or a line out of a synth) symmetrical to feed long XLR-lines (stage-boxes with multicore) to a symmetrical mixing unit or similar. What you mean is a preamp that makes a low-level to high-level shifting (to avoid the damned noise of mic-amp). This can be realized with several low-noise OP-Amps like INA 217 or some OPA-types (works also with symmetrical TL 071-074). I plan to offer some circuits to make such things for yourself. I say if it´s finished, okay?!

Greetings!

TravelRec.

Tiger M · Jun 25, 2004, 07:36 AM

>Sorry guys, but a D.I. box is some different from what you said

No, actually I was quite right. There are D.I. Boxes with a pre-amp and I've personally used one.

FAQ:

Q: What is a direct box anyway?
A: A direct box is an impedance matching and signal-balancing device. DI's convert hi-impedance instrument signals to mic-level balanced lines for interface with pro-audio equipment such as mixing consoles. A good direct box will ensure proper electrical signals are maintained throughout the signal chain and allow long cable runs without added noise.

Q: What is the difference between a passive and an active DI?
A: Passive direct boxes use a transformer to convert the electrical signals while active direct boxes use an amplifier circuit. Passive boxes have the advantage of providing isolation which can reduce ground hum in systems.

They are a good addition when plugging your guitar directly through line-in on sound cards, because of the low impendance of some cards and the high impendance of guitars.

Maybe I'm wrong...

Tiger M · Jun 25, 2004, 09:09 AM

btw, TravelRec., you're absolutely right about what you wrote. The only thing is that there are normal D.I. boxes with no additional extras and boxes with a pre-amp or amp-simulation for instance, which are more expensive.

It would be nice if you could provide some circuits.

I was wondering, do you have any schematics for an average to good quality guitar pre-amp (high input impendance) with good s/n ratio. I mean simple stuff with just a level pot or somehing. I just want to get rid of that bulky mixer that I use for pre-amp off my desk.

Thanks.

ReWired · Jun 25, 2004, 04:25 PM

Thanks for all your replies

I will by one DI Box.
Anyway, untill it comes to my door, I will use a preamp (I have one....hidden in the basement

)))

Tiger M · Jun 25, 2004, 04:57 PM

Note that, as Traverec said, most standart DIBoxes are not preamps. Ask before you buy.

ReWired · Jun 25, 2004, 08:52 PM

actually I need a preamp, but always when I asked for this - heard something similar to this "buy a DI Box, try a DI Box, I use DI Box and everything sounds much better with it"...etc.
anyway, this community is great

I am not posting here, because for all my questions someone already answered in the forum

keep working, this project is best free one I ever saw

Lex Nahumury · Jun 26, 2004, 03:26 AM

Quote:

Originally posted by Tiger M
I was wondering, do you have any schematics for an average to good quality guitar pre-amp (high input impendance) with good s/n ratio. I mean simple stuff with just a level pot or somehing. I just want to get rid of that bulky mixer that I use for pre-amp off my desk.
Thanks.

A simple discrete component FET-buffer + amplification stage to bring the guitar signal up to Line Level always worked for me.
BTW; One thing often overlooked in "D.I"-ing an electric guitar is capacitance.
It's not all about 'matching' impendance and amplification.
The guitars pickup's coil inductance + cable capacitance + amp's input impendance
forms a Lopass filter with Resonance peak wich is typical for the "classic" electric guitar -> cable-> guit amp sound.

Using a FET input stage you are 'free' to set the desired impendance by placing a load resistor on it's input.
(Typicly this would be 470 KOhm as used in most guit amps and stomp boxes)
Also; In studio enviroments were guitar cables can get short, cable capacitance will drop, affecting the tone.
Adding a capacitor in paralel with the input resistor can compensate for this.

Making both input impendance and input capacitance of a studio guit pre-amp selectable
via a rotary switch is a nice addition. (and amplification ofcourse)

/LeMury

Tiger M · Jun 26, 2004, 05:16 AM

Thanks for the info.

I found a similar circuit on the web, very simple, but needs a speciffic FET (the author says that most other FATs won't work?) that is hard to find.

I'll try to find it anyway.

**dj_stick** · Jun 26, 2004, 05:20 AM

i'm sure travelrec could help you find an alternative component

Tiger M · Jun 26, 2004, 10:35 AM

He seems to be very experienced with electronics.
I used to be building some effect circuits myself, but them I found in the backyard that pot full of gold...

TravelRec. · Jun 28, 2004, 07:18 PM

Yo!

Guitar amp??? This could also be done with an IC from BurrBrown (TI) called INA217, this is a balanced instrumentation amp with very low noise and quick response. But I have not tested this yet. Will do this when I meet "my" guitarist again in 2 weeks or so. Unfortunately now there is no time for electronics

but I still remember you. The INA 217 here is working as Mic-Amp for condenser mics and it has very good performance in S/N ratio. If you are a bit patient, I will help you with the circuit or I´ll check another one that meets your specifications! Sorry, but I´m not a guitarist, more electronic musician, so I needed other things in the past...

Bye then!

TravelRec.

Jun 24, 2004, 04:00 PM	#1
ReWired HardwareHeaven Lover Join Date: Nov 2003 Posts: 100 Rep Power: 0	D.I. Box ? Probably this question is too stupid...if so, please, excuse me I don't know what exactly is this hardware D.I. Box and what it does.... Anyway, my question is: Can this D.I. Box be emulated using the present kX DSP effects? And if yes - which ones will do the job? Thanks in advance!

Jun 25, 2004, 06:21 AM	#5
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	D.I. Box = Direct Input Box. They're good for the high input impendance and the balanced low output impendance they produce. A good cheap pre-amp solution (espetially with the kX DSP where you have full control over the sound, that is you don't need any pre-amp filtering). NOTE: Some need phantom power. __________________ Miss you, Steve...

Jun 25, 2004, 06:27 AM	#6
TravelRec. Alternative Audioproductions Join Date: Sep 2003 Location: Germany / Sachsen-Anhalt Posts: 1,710 Rep Power: 0	Hi! Sorry guys, but a D.I. box is some different from what you said: it is only a cable converter, not a level-shifter nor a preamp. It can be passive (with a transformer) or active (with OP-Amps). A D.I. box is used to make unsymmetrical signals (just from guitar or mic or a line out of a synth) symmetrical to feed long XLR-lines (stage-boxes with multicore) to a symmetrical mixing unit or similar. What you mean is a preamp that makes a low-level to high-level shifting (to avoid the damned noise of mic-amp). This can be realized with several low-noise OP-Amps like INA 217 or some OPA-types (works also with symmetrical TL 071-074). I plan to offer some circuits to make such things for yourself. I say if it´s finished, okay?! Greetings! TravelRec. __________________ Always take a look behind.

Jun 25, 2004, 07:36 AM	#7
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	>Sorry guys, but a D.I. box is some different from what you said No, actually I was quite right. There are D.I. Boxes with a pre-amp and I've personally used one. FAQ: Q: What is a direct box anyway? A: A direct box is an impedance matching and signal-balancing device. DI's convert hi-impedance instrument signals to mic-level balanced lines for interface with pro-audio equipment such as mixing consoles. A good direct box will ensure proper electrical signals are maintained throughout the signal chain and allow long cable runs without added noise. Q: What is the difference between a passive and an active DI? A: Passive direct boxes use a transformer to convert the electrical signals while active direct boxes use an amplifier circuit. Passive boxes have the advantage of providing isolation which can reduce ground hum in systems. They are a good addition when plugging your guitar directly through line-in on sound cards, because of the low impendance of some cards and the high impendance of guitars. Maybe I'm wrong... __________________ Miss you, Steve...

Jun 25, 2004, 09:09 AM	#8
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	btw, TravelRec., you're absolutely right about what you wrote. The only thing is that there are normal D.I. boxes with no additional extras and boxes with a pre-amp or amp-simulation for instance, which are more expensive. It would be nice if you could provide some circuits. I was wondering, do you have any schematics for an average to good quality guitar pre-amp (high input impendance) with good s/n ratio. I mean simple stuff with just a level pot or somehing. I just want to get rid of that bulky mixer that I use for pre-amp off my desk. Thanks. __________________ Miss you, Steve...

Jun 24, 2004, 11:37 PM	Thread Starter #3
ReWired HardwareHeaven Lover Join Date: Nov 2003 Posts: 100 Rep Power: 0	So, this is a preamp, with some sort of noise reduction?

Jun 25, 2004, 04:25 PM	Thread Starter #9
ReWired HardwareHeaven Lover Join Date: Nov 2003 Posts: 100 Rep Power: 0	Thanks for all your replies I will by one DI Box. Anyway, untill it comes to my door, I will use a preamp (I have one....hidden in the basement)))

Jun 25, 2004, 04:57 PM	#10
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	Note that, as Traverec said, most standart DIBoxes are not preamps. Ask before you buy. __________________ Miss you, Steve...

Jun 25, 2004, 08:52 PM	Thread Starter #11
ReWired HardwareHeaven Lover Join Date: Nov 2003 Posts: 100 Rep Power: 0	actually I need a preamp, but always when I asked for this - heard something similar to this "buy a DI Box, try a DI Box, I use DI Box and everything sounds much better with it"...etc. anyway, this community is great I am not posting here, because for all my questions someone already answered in the forum keep working, this project is best free one I ever saw

Jun 26, 2004, 05:16 AM	#13
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	Thanks for the info. I found a similar circuit on the web, very simple, but needs a speciffic FET (the author says that most other FATs won't work?) that is hard to find. I'll try to find it anyway. __________________ Miss you, Steve...

Jun 26, 2004, 10:35 AM	#15
Tiger M kX user Join Date: Apr 2004 Posts: 851 Rep Power: 0	He seems to be very experienced with electronics. I used to be building some effect circuits myself, but them I found in the backyard that pot full of gold... __________________ Miss you, Steve...

Jun 28, 2004, 07:18 PM	#16
TravelRec. Alternative Audioproductions Join Date: Sep 2003 Location: Germany / Sachsen-Anhalt Posts: 1,710 Rep Power: 0	Yo! Guitar amp??? This could also be done with an IC from BurrBrown (TI) called INA217, this is a balanced instrumentation amp with very low noise and quick response. But I have not tested this yet. Will do this when I meet "my" guitarist again in 2 weeks or so. Unfortunately now there is no time for electronics but I still remember you. The INA 217 here is working as Mic-Amp for condenser mics and it has very good performance in S/N ratio. If you are a bit patient, I will help you with the circuit or I´ll check another one that meets your specifications! Sorry, but I´m not a guitarist, more electronic musician, so I needed other things in the past... Bye then! TravelRec. __________________ Always take a look behind.