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Input Impedance, active DI box

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Input Impedance, active DI box

Postby damartin » Mon Sep 21, 2020 7:45 am

Hello guys, again with a technical question.

I inted to buy an inexpensive active DI box (Behringer DI 100 https://www.behringer.com/product.html?modelCode=P0062). I am a little confused about the specifications, especially by the input impedance. it reads ">250kOhm". What does this mean? the input impedance is variable in active DIs? I surveyed the marked and I've encountered active DI boxes with 1MOhm input impedance. I plan to use my DI box for my guitar into a Xenyx802 mixer (for example). It's seems that 250kOhm is almost the minimun for a guitar. For example my Behringer UMC202HD audio interface has the input impedance for instrument around 1MOhms. So, once again why “>“ and not “=“ in DI100 specifications. Thanks!
Martin
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Re: Input Impedance, active DI box

Postby Kwackman » Mon Sep 21, 2020 8:52 am

Hopefully someone with more knowledge will be along shortly, but what sort of guitar are you plugging in?
If it's an electric, I believe the at least 1MΩ is the rule.
But for acoustic guitars (active electronics) the requirements aren't the same.
That DI box you linked to has no reference to electric guitar, so probably not fit for that purpose.
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Re: Input Impedance, active DI box

Postby blinddrew » Mon Sep 21, 2020 9:25 am

Behringer make a lot of good products these days, the DI100 isn't one of them though. I'd definitely suggest looking at something else. Or anything else.
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Re: Input Impedance, active DI box

Postby damartin » Mon Sep 21, 2020 9:34 am

Thanks!
PS: Indeed, I intend to plug in an electric guitar (humbuckers)
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Re: Input Impedance, active DI box

Postby The Elf » Mon Sep 21, 2020 9:58 am

Seriously, those Behringer DIs are utter junk. Invest a smudge more and get something that doesn't ruin your audio by covering it all in noise. A lot of folks here recommend Orchid - I don't have a DI of theirs, but I know they make good kit.
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Re: Input Impedance, active DI box

Postby Sam Spoons » Mon Sep 21, 2020 10:40 am

Yup, Berry DI100 and DI120, utterly horrible bits of kit. Buy an Orchid Classic DI for £39 (or, if money is really tight and you don't need battery power or a link output, the Micro DI for £28)

http://orchid-electronics.co.uk/classic_DI.htm

http://orchid-electronics.co.uk/micro.htm
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Re: Input Impedance, active DI box

Postby blinddrew » Mon Sep 21, 2020 11:40 am

Sorry, thought I'd put this in my previous reply but I appear to have managed to delete it, but another +1 for Orchid DIs. I have two. :)
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Re: Input Impedance, active DI box

Postby Luke W » Mon Sep 21, 2020 11:51 am

Another vote against the DI100 here. It's not uncommon to see a lot of hate towards Behringer and a lot of their perfectly decent kit can get unfairly slated. That said, every DI box of theirs I've ever encountered has sounded like a wasp in a coke can.
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Re: Input Impedance, active DI box

Postby ef37a » Mon Sep 21, 2020 1:12 pm

Yes the Behringer DIs are pretty universally known to be noisy junk so go Orchid.

But, in the matter of the input impedance this is not AS important as is often made out.

Yes, the 'Magic Meg' is often quoted as being the bizz but that is largely a hangover from valve radio days! Then, DI boxes invariably have a parallel jack to feed an amplifier so you can mix in a microphone, jack in an amp the load is now 0.5meg! I have never heard or read of anyone being bothered or noticing a change of tone when an amp is slaved to a DI box?

They are all about a meg these days but only a few years ago the instrument input of many AIs was less than 1M and in some cases as low as 100k Ohms. Again I never read of a single complaint nor even a mention of it in a review.

The source impedance of even a basic electric guitar is complex, at least two pickups as a rule, tone and volume pots and stuff switched in and out (and out of phase!) That lot interacts with the cable capacitance (and not to give a simple 'Top Loss' in many cases) the load at the end has only a marginal effect unless very low. A 10k line input will give a gross signal loss as well as tonal changes.

The situation with piezo passive acoustics is rather different. They need to see 5, better 10 megs or they lack bass.

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Re: Input Impedance, active DI box

Postby damartin » Mon Sep 21, 2020 1:41 pm

Thanks you all for replying.
I really like this Forum. Got really informative and helpful answers especially that I am a newbie to this world.
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Re: Input Impedance, active DI box

Postby Alba » Mon Sep 21, 2020 3:15 pm

If money is tight and you're handy with a soldering iron you could make one of these.

http://www.till.com/articles/GuitarPreamp/

There's a veroboard version here...

http://tagboardeffects.blogspot.com/201 ... llman.html
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Re: Input Impedance, active DI box

Postby ef37a » Mon Sep 21, 2020 4:00 pm

Alba wrote:If money is tight and you're handy with a soldering iron you could make one of these.

http://www.till.com/articles/GuitarPreamp/

There's a veroboard version here...

http://tagboardeffects.blogspot.com/201 ... llman.html

Yes, useful little circuit I have used in the past but if like me you have TL072s handy, bit of a waste of time. The guy is entitled to his opinion but is largely talking bllx about op amps.

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Re: Input Impedance, active DI box

Postby shufflebeat » Mon Sep 21, 2020 4:10 pm

ef37a wrote:Yes, the 'Magic Meg' is often quoted as being the bizz...

She certainly is.

I have no idea why those Behringer boxes still exist. They could have been improved over the years, possibly with flight feathers to make them easier to aim, or a built in cigarette lighter, but they keep pooping them out and people apparently still buy them.

I wonder if there's a message in all this.

+1 for Orchid, I have 3x 2ch boxes.
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Re: Input Impedance, active DI box

Postby twotoedsloth » Mon Sep 21, 2020 5:25 pm

I would also highly recommend the Orchid DIs. What's particularly great is if you have a specific need, they will make exactly what you're looking for. Just tell him what you want. I bought a DI with a -50db pad to knock a relatively hot line output down to mic level. Most of the off the shelf options only did -20db. I also bought a transformer isolator with XLR ins and outs. Really great gear, and reasonably priced.
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Re: Input Impedance, active DI box

Postby Dan LB » Mon Sep 21, 2020 7:11 pm

Another +1 for Orchid. I have 4 of their Micro DIs and they are excellent. Used to have a Behringer or 2 many moons ago and I can confirm they are utter sh1te! They do make some great bits of kit these days but as Drew says, their DIs are not in that category.
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