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Adding an instrument input to a mic preamp?
Old 15th December 2014
  #1
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elambo's Avatar
Adding an instrument input to a mic preamp?

I have a few mic pres which I like (Avedis MA5, John Hardy Twin-Servo, Neve 1272, among others) and I'm looking for the best way to use these with guitar and bass since they don't have an instrument input. What should I be considering? Radial JDI? Ideally something clean since I'd be picking those particular pres for their own color and wouldn't need/want a tone shift.
Old 15th December 2014
  #2
There are many many DI boxes on the market. I use a Radial J48 and am quite happy with it. You have to choose between active and passive. In either case, look for a box with Jensen transformers, ground lifts, etc. There are also a lot of tube DI's, but those obviously will add color. Sometimes you want that color, other times not.
Old 15th December 2014
  #3
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Indeed the Radials are a sort of standard for this purpose, but if I'm going to buy one I was curious to know if there was something even better, even if a bit more $$. "Better" being more transparent in this case.
Old 15th December 2014
  #4
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Quote:
Originally Posted by elambo View Post
I have a few mic pres which I like (Avedis MA5, John Hardy Twin-Servo, Neve 1272, among others) and I'm looking for the best way to use these with guitar and bass since they don't have an instrument input. What should I be considering? Radial JDI? Ideally something clean since I'd be picking those particular pres for their own color and wouldn't need/want a tone shift.
Get a nice DI. There are many to choose from.
Old 15th December 2014
  #5
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Yes, but I'm hoping to get opinions on what's better than a Radial. Or maybe this is one of those things where there's no reason to look beyond the JDI. I rarely use DIs.
Old 15th December 2014
  #6
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Steele's Avatar
 

I use an "Evil Twin. Tube DI. Great as a Mic Pre as well.
Old 15th December 2014
  #7
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elambo's Avatar
That's a great DI, no doubt, but my pres are already colored (not the Hardy of course) so I think a clean DI will be needed in this case.
Old 15th December 2014
  #8
Quote:
Originally Posted by elambo View Post
Yes, but I'm hoping to get opinions on what's better than a Radial. Or maybe this is one of those things where there's no reason to look beyond the JDI. I rarely use DIs.
Very good info here:
A Direct Box can be in-DI-spensible - Support - Whirlwind

and here:
Q Why are some DI boxes expensive?

The main decision is passive vs active. In my experience active will sound more transparent. Passive can dull the highs a bit, depending on the impedance of the source. Tube DI's can get very expensive and certainly can be worth it if you are going for a certain sound, but in your case you said you want transparent.

Some great tube DI's:
Demeter
Evil Twin (if you can get one, I think they are hand made and hard to get)
Valvotronics
Manley
Old 15th December 2014
  #9
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elambo's Avatar
The chain will be guitar/bass to Lehle Sunday Driver so impedance shouldn't be an issue for a passive design. On the other hand, if I could forgo the Sunday Driver and get an active DI for two-birds-with-one-stone... that could be beneficial, especially when it's not handy to use the Sunday. Is the J48 and active version of the JDI (more or less)?
Old 15th December 2014
  #10
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tekis's Avatar
Retrospec Juice Box is one that I've been using for a long while. It's a tube di but transformerless.

Retrospec Audio
Old 15th December 2014
  #11
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Hi
Active 'DI' units (or inputs) use transistors or valves to give the high impedance characteristic and the 'load' they present to the input is very much resistive (a resistor) so the influence on the frequency response will be about as 'neutral' as you can get. As long as it has been designed properly the distortion produced will also be minimal.
Active DI units tend to have around 'unity gain' unless specified so are essentially impedance conversion devices.
Transformer DI units have a REACTIVE element to them and will have a complex relationship with frequency and depending on the 'quality' of the transformer, distortion. Jensen transformers are usually among the few with very little distortion although they manufacture a large range of units and individual types will be more suited to the application.
Transformers are pretty complex devices once you get past their apparent 'simplicity'. They must be correctly specified for input characteristics, output characteristics, the frequency range required, the distortion permitted and the signal LEVEL that is expected. MIC transformers are quite different to LINE transformers which are different again to power transformers. Any transformer which has say 1:3 ratio will be essentially similar from these 3 main 'groupings' but when tried in your application only one design will manage to fulfill all the requirements properly.
Passive transformer DI units 'trade' a medium voltage at 'high impedance' for a lower voltage at lower impedance. It is the low impedance characteristic that allows longer cables to be used without influencing the frequency response. You 'pay' for this benefit by having to apply more gain with the preamplifier.
Matt S
Old 15th December 2014
  #12
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For acoustic GTR's, Bass and piezo's on violins I use active DI's.
For syths a passive DI is fine. Plus a passive DI is useful as an (extra) reampbox.

So I would recommend: get at least one of each.
Or more if you tend to do stereo stuff.

As an active DI the Klark Teknik DN100 is great and cheap.
For passive go for a Radial Engineering ProDI.

Anything cheaper is stupid anything more expensive is a waste of money.
Old 15th December 2014
  #13
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Woodwindy's Avatar
These would be great choices:
http://youtu.be/IvJwQay_7eI
Old 15th December 2014
  #14
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elambo's Avatar
Clean is key. No tubes, at least not those with audible effects. As mentioned, I already have plenty of options with character.

I'm going to see how the Sunday Driver (which I already have) responds when connected directly to these pres. I'll let you know how it goes.
Old 15th December 2014
  #15
Try out a NPNG "Diehlio" Active Direct box.
Old 15th December 2014
  #16
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elambo's Avatar
Quote:
Originally Posted by Doc Mixwell View Post
Try out a NPNG "Diehlio" Active Direct box.
I didn't realize he made a DI. Interesting. Checking that out now...
Old 15th December 2014
  #17
Here are the specs
price is $250, it is two isolated channels
Attached Thumbnails
Adding an instrument input to a mic preamp?-diehlio_spec_final.jpg  
Old 15th December 2014
  #18
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The Hamptone HPDI is great too
Old 15th December 2014
  #19
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Quote:
Originally Posted by elambo View Post
Yes, but I'm hoping to get opinions on what's better than a Radial.
Just get the Jensen transformer and make your own. From what I read, Radial stopped using the Jensen anyway.
Old 15th December 2014
  #20
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elambo's Avatar
Quote:
Originally Posted by Kronos147 View Post
Just get the Jensen transformer and make your own. From what I read, Radial stopped using the Jensen anyway.
I remember that rumor going around, and maybe they even switched a few models for awhile, but Radial is still using the Jensen today. That was something I checked on.
Old 15th December 2014
  #21
Quote:
Originally Posted by elambo View Post
I remember that rumor going around, and maybe they even switched a few models for awhile, but Radial is still using the Jensen today. That was something I checked on.
Radial actually bought the Jensen company so that they could ensure their supply:

Jensen Transformers Acquired by Radial Engineering - Article from CE Pro
Old 15th December 2014
  #22
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Kronos147's Avatar
Quote:
Originally Posted by elambo View Post
I remember that rumor going around, and maybe they even switched a few models for awhile, but Radial is still using the Jensen today. That was something I checked on.
My bad, here is what I was thinking:
"The heart of the ProDI is a custom wound Radial transformer."

Radial ProDI™ - Passive Direct Box

I seem to recall a period of time that Radial considered moving away from Jensen. That's not the case anymore!

Eric
Old 15th December 2014
  #23
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avare's Avatar
 

Quote:
Originally Posted by Kronos147 View Post
My bad, here is what I was thinking:
"The heart of the ProDI is a custom wound Radial transformer."

Radial ProDI™ - Passive Direct Box

I seem to recall a period of time that Radial considered moving away from Jensen. That's not the case anymore!

Eric
I am not clear on what you are meaning and the appropriateness to the topic. The JDI uses Jensen transformers. Radial's lower priced products do not. The OP wants as clean a sound as possible, so an active DI will be a better topology for him.
Old 15th December 2014
  #24
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elambo's Avatar
Quote:
Originally Posted by Kronos147 View Post
I seem to recall a period of time that Radial considered moving away from Jensen. That's not the case anymore!
That's true, and a lot of people weren't excited about that idea. Thankfully, Radial is one of those companies which listens to their customers.
Old 16th December 2014
  #25
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Quote:
Originally Posted by avare View Post
I am not clear on what you are meaning and the appropriateness to the topic.
Regarding the appropriateness, in an earlier post I made the assertion:

Quote:
Originally Posted by Kronos147 View Post
Just get the Jensen transformer and make your own. From what I read, Radial stopped using the Jensen anyway.
To which I was told:

Quote:
Originally Posted by elambo View Post
I remember that rumor going around, and maybe they even switched a few models for awhile, but Radial is still using the Jensen today. That was something I checked on.
Followed by:

Quote:
Originally Posted by jweisbin View Post
Radial actually bought the Jensen company so that they could ensure their supply:

Jensen Transformers Acquired by Radial Engineering - Article from CE Pro
I read the information, realized the error of my ways, which is why I posted:

Quote:
Originally Posted by Kronos147 View Post
My bad, here is what I was thinking:
"The heart of the ProDI is a custom wound Radial transformer."

Radial ProDI™ - Passive Direct Box
Bottom line, I was wrong, I copped to it, and instead of deleting my post to cover up my error I wanted to make sure if someone reads all the way through they get the real 411.

Eric
Old 16th December 2014
  #26
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avare's Avatar
 

Quote:
Originally Posted by Kronos147 View Post
I read the information, realized the error of my ways, which is why I posted:



Bottom line, I was wrong, I copped to it, and instead of deleting my post to cover up my error I wanted to make sure if someone reads all the way through they get the real 411.
My apologies. You did superbly.

Andre
Old 16th December 2014
  #27
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bash's Avatar
 

Back on topic, the Empirical Labs EL500 rack features a DI for 500 series preamps without Hi-Z inputs.

EL500
Old 16th December 2014
  #28
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elambo's Avatar
Quote:
Originally Posted by bash View Post
Back on topic, the Empirical Labs EL500 rack features a DI.

EL500
I saw that recently, and if I were diving into more 500-series pres that's probably what I'd get. I'm actually surprised that that's the only one (that I know of) that has a DI. Seems like a handy option - maybe it'll catch on. Or maybe they figure everyone and their mother already has a DI so why bother.

My current pres aren't 500-series (one is but it's already happily racked) so I'm leaning toward the NPNG cuz he makes top-shelf stuff and $125/channel is a helluva good deal.
Old 16th December 2014
  #29
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Kronos147's Avatar
Quote:
Originally Posted by avare View Post
My apologies.

Andre
No apologies required. No offense was taken. Rock on!
Old 16th December 2014
  #30
Quote:
Originally Posted by elambo View Post
I'm leaning toward the NPNG cuz he makes top-shelf stuff and $125/channel is a helluva good deal.
Here is an internal gut shot! This DI was designed for capturing an instrument direct, VERY clean, no coloration, no harshness either!
just your instrument and whatever preamp ya like!
Attached Thumbnails
Adding an instrument input to a mic preamp?-diehlio_spec_final2.jpg  
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