DaxLiniere

Passive DI = ReAmp = Passive DI???
« on: March 30, 2009, 05:33:26 PM »
Just a thought, assuming you had a good quality passive DI box, couldn't that be used as a reamping unit?
(Modify the unit so it has both male and female XLRs)

Further to that, could 2 good quality passive DI boxes be used end to end (XLR>XLR) to noiselessly extend a guitar line?
Dax Liniere

PUZZLE FACTORY
SOUND STUDIO
Sydney, Aust.

www.puzzlefactory.com.au - now with VR!
 _________________ Warning: Do not look into beam with remaining eye


mattnj

Re: Passive DI = ReAmp = Passive DI???
« Reply #1 on: March 30, 2009, 07:47:28 PM »
Ive used passive DIs for reamping with reasonably good results. As far as line balancing, I don't know although that may be what the radial system does.  Give it a try!

mcfarlane_audio

Re: Passive DI = ReAmp = Passive DI???
« Reply #2 on: March 31, 2009, 10:01:24 AM »
ive done it many times, for reamping (i made myself a "lesbian" adapter cable) and i have also used "piggybacked" di's to extend a guitar signals

good luck!
Quote from: "pucho812"
yeah some guy named OHM invented this law which dictates all the crap we do

tv

Re: Passive DI = ReAmp = Passive DI???
« Reply #3 on: March 31, 2009, 10:07:50 AM »
For back-to-back DI, check that there is pure trafo-trafo connection (i.e. coil-coil direct; no capacitors in the circuit).
If you sprinkle when you tinkle, please be neat and wipe the seat.

DaxLiniere

Re: Passive DI = ReAmp = Passive DI???
« Reply #4 on: March 31, 2009, 06:34:34 PM »
(..no capacitors in the circuit).
AHH, that's the kind of thing I had in mind. Excellent thinking TV!
Dax Liniere

PUZZLE FACTORY
SOUND STUDIO
Sydney, Aust.

www.puzzlefactory.com.au - now with VR!
 _________________ Warning: Do not look into beam with remaining eye

sahib

Re: Passive DI = ReAmp = Passive DI???
« Reply #5 on: March 31, 2009, 07:16:18 PM »
Further to that, could 2 good quality passive DI boxes be used end to end (XLR>XLR) to noiselessly extend a guitar line?

It would only make it better in terms of the noise picked up throught the cable between the effect units and the amp.

The noise that is picked up through the cable between the guitar and effect units, and the additional noise generated by the effect units themselves will still remain.

DaxLiniere

Re: Passive DI = ReAmp = Passive DI???
« Reply #6 on: March 31, 2009, 08:07:05 PM »
Ahh yes, but assuming you have short jack->jack leads on each end of the DI boxes, you'd be fine. Cool.
Thanks Sahib!
Dax Liniere

PUZZLE FACTORY
SOUND STUDIO
Sydney, Aust.

www.puzzlefactory.com.au - now with VR!
 _________________ Warning: Do not look into beam with remaining eye

sahib

Re: Passive DI = ReAmp = Passive DI???
« Reply #7 on: March 31, 2009, 08:12:29 PM »

You are welcome.

Silvas

Re: Passive DI = ReAmp = Passive DI???
« Reply #8 on: April 01, 2009, 08:12:58 PM »
ive done it many times, for reamping (i made myself a "lesbian" adapter cable) and i have also used "piggybacked" di's to extend a guitar signals

good luck!

+1

extremely helpful under difficult studio situations.
Camilo Silva F.
Camilo Silva F. Mastering
Chia, Colombia

Whoops

Re: Passive DI = ReAmp = Passive DI???
« Reply #9 on: April 13, 2009, 09:45:34 PM »
Please correct me if I'm wrong but,

A Reamp-Box converts Line Level Signals to Instrument

A Passive DI used backwards converts Mic Level to Instrument Level

Mic Level has a different impedance than line level, so it works but it's not the same.


 "
Further to that, could 2 good quality passive DI boxes be used end to end (XLR>XLR) to noiselessly extend a guitar line?

to do this properly I think you will need some kind of buffering stage in the Emitter DI. That's what the Radial system has (besides Jensen transformers)


Whoops

Re: Passive DI = ReAmp = Passive DI???
« Reply #10 on: April 13, 2009, 09:49:54 PM »
check this Jensen schematic for a reamp box:

http://www.jensen-transformers.com/as/as092.pdf

DaxLiniere

Re: Passive DI = ReAmp = Passive DI???
« Reply #11 on: April 17, 2009, 05:02:23 AM »
Please correct me if I'm wrong but,

A Reamp-Box converts Line Level Signals to Instrument

A Passive DI used backwards converts Mic Level to Instrument Level

 :'(  Yes, I am a collossal idiot - you are completely correct... (darn, where's the "delete history to cover stupid mistake" button? )

Next time, maybe I'll switch my brain on before posting.
Dax Liniere

PUZZLE FACTORY
SOUND STUDIO
Sydney, Aust.

www.puzzlefactory.com.au - now with VR!
 _________________ Warning: Do not look into beam with remaining eye

Rossi

Re: Passive DI = ReAmp = Passive DI???
« Reply #12 on: April 17, 2009, 06:08:59 AM »
A lot of people seem to believe that passive is always better than active. But when it comes to DI, passive boxes are merely a compromise.

A typical mic input is about 1.5k impedance. A typical passive DI has a 10:1 step down transformer, so the guitar sees an imput impedance of about 150k. That's much lower than is desired (500k-5M) - the guitar pick up will be loaded down and lose part of its presence peak. Of course 150k is still better than a 10k line in but nowhere as good as a "real" instrument input. A guitar amp input is typically 1M, active DI boxes are about the same. The passive DI concept is merely a compromise between impedance increase and level loss. An active DI will give you higher impedance and higher level at the same time. A passive device can't do that. A passive DI will also load down your guitar input, if both are connected in parallel, so your amp tone will suffer to some degree.

Reversing a passive DI for reamping will give you level increase and impedance increase when you really want a somewhat lower level than a typical line out (many converters put out insane levels) and higher impedance (to simulate the guitar PU).

So while a passive box does work both ways, it isn't ideal in either direction. That's not to say you won't like the results. But if you want to capture your guitar signal uncolored, an active DI is the way to go; and if you're heavily into reamping, get aa genuine reamping solution (which can be passive without compromises but it's not just a reversed passive DI)
"I am not a number, I'm a free man!"
"Hahahahaaaaaa!!!!!"

Whoops

Re: Passive DI = ReAmp = Passive DI???
« Reply #13 on: April 17, 2009, 06:42:04 AM »
A typical mic input is about 1.5k impedance. A typical passive DI has a 10:1 step down transformer, so the guitar sees an imput impedance of about 150k. That's much lower than is desired (500k-5M) - the guitar pick up will be loaded down and lose part of its presence peak. Of course 150k is still better than a 10k line in but nowhere as good as a "real" instrument input.

A passive DI will also load down your guitar input, if both are connected in parallel, so your amp tone will suffer to some degree.

Great Post!

I didn't know that a passive DI would give a lower impedance for the guitar than desired.
I normally use a passive DI that I own with Jensen transformer, and to be honest it always sounded much better than all my other Active DI's,
so maybe the difference it's in the Jensen transformer itself and not the fact that it is passive.

What I really don't like, and you are also totally right on that, is when the amp out of a passive DI is a parallel of the input. The amp Tone and the DI tone both seem to suffer quite dramaticly.


dandeurloo

Re: Passive DI = ReAmp = Passive DI???
« Reply #14 on: April 17, 2009, 12:48:57 PM »
I tried to do a search and did see anyone offering a PCB or a kit for Passive or Active Di's.  Are then out there?  Would it be anything would wan to do?  Seems like something everyone needs a number of and would be fun little projects for newbies like me.
PROFESSIONAL CHASSIS AND FRONT PANELS FOR DIY PROJECTS: WWW.COLLECTIVECASES.COM

Dan Deurloo
www.collectivecases.com
www.risendrums.com

Whoops

Re: Passive DI = ReAmp = Passive DI???
« Reply #15 on: April 17, 2009, 07:09:47 PM »
I tried to do a search and did see anyone offering a PCB or a kit for Passive or Active Di's.  Are then out there?  Would it be anything would wan to do?  Seems like something everyone needs a number of and would be fun little projects for newbies like me.

You could use the JLM Fet DI as a standalone project, it sounds great.

http://www.jlmaudio.com/



 

Related Topics

  Subject / Started by Replies Last post
12 Replies
3408 Views
Last post July 20, 2004, 06:06:10 PM
by clintrubber
3 Replies
1386 Views
Last post March 22, 2008, 11:43:18 AM
by plunderpot1
1 Replies
1510 Views
Last post May 03, 2012, 08:06:50 AM
by MrZpliff
7 Replies
674 Views
Last post December 09, 2018, 04:14:20 AM
by ruffrecords