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200 ohm or 600 ohm output impedance in DI Box?
Old 4 days ago
  #1
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Thread Starter
200 ohm or 600 ohm output impedance in DI Box?

Radial J48 has 600 ohm output impedance, but I chose another DI Box that has 200 ohm output impedance. I want to record electric guitar in my audio interface through DI box. Which impedance is better?
also, how it is that 20$ behringer DI box sounds exactly the same as 200$ Radial J48? Here is comparison test recordings:
https://www.youtube.com/watch?v=VcKvf6bKPbA
Old 4 days ago
  #2

Well, the 200 ohm one should have just a little less noise (hiss). But, both are sufficiently low to work fine for guitar into nearly any modern mic pre-amp...

As for the quality of the cheaper unit: Guitars are easy. The bandwidth doesn't go very high or low and the inductive nature of the pickups combined with the low signal level are easy for transformers to deal with...

Try plugging a hot analog synth doing bass patches into each box - you'll probably hear a difference there.



-tINY

Old 4 days ago
  #3
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Thread Starter
Quote:
Originally Posted by tINY View Post

Well, the 200 ohm one should have just a little less noise (hiss). But, both are sufficiently low to work fine for guitar into nearly any modern mic pre-amp...

As for the quality of the cheaper unit: Guitars are easy. The bandwidth doesn't go very high or low and the inductive nature of the pickups combined with the low signal level are easy for transformers to deal with...

Try plugging a hot analog synth doing bass patches into each box - you'll probably hear a difference there.



-tINY

Thanks for answer. So there is no such thing as too low output impedance? First I thought that 200 ohm are worse than 600 ohm, since most DI boxes have 600 ohm output.
Also is it true that if I connect DI box to my interface with phantom power on, then I wil not be able to use Ground Lift knob?
Old 4 days ago
  #4

IT depends. On the good one, there is a coupling cap on the secondaries which will prevent DC current from flowing. The cheap one... maybe.

But, the DC resistance of the secondaries is not 200/600 ohms. Those ratings are the reflected AC impedance if the primary is loaded as indicated. So, a typical 10k/600ohm DI transformer is 300 ohms output impedance with 5k source on the other end. Additionally, the phantom power should have limiting resistors and most mic pre-amps are designed to survive a direct short....

Finally, the ground lift should only dis/connect the 'low" side of the primary to ground (pin 1 on the XLR). So, it won't make any difference on the output side.



-tINY

Old 4 days ago
  #5
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Thread Starter
Quote:
Originally Posted by tINY View Post

IT depends. On the good one, there is a coupling cap on the secondaries which will prevent DC current from flowing. The cheap one... maybe.

But, the DC resistance of the secondaries is not 200/600 ohms. Those ratings are the reflected AC impedance if the primary is loaded as indicated. So, a typical 10k/600ohm DI transformer is 300 ohms output impedance with 5k source on the other end. Additionally, the phantom power should have limiting resistors and most mic pre-amps are designed to survive a direct short....

Finally, the ground lift should only dis/connect the 'low" side of the primary to ground (pin 1 on the XLR). So, it won't make any difference on the output side.



-tINY

My audio intreface Steinberg ur242 actually has one input that has Hi-Z knob, specially for guitars and bases. But I still find my guitar sounding very noisy. That means that there is not as good convertion of Hi-Z impedance as in separate DI box?
Will DI box help to clean DI signal of my guitar? even if my interface has build in Hi-Z knob?
Old 4 days ago
  #6

Depends how good that Hi-Z input is... I'd start with the cheap DI - it probably has a more limited frequency response - which helps keep noise down.

The other trick to try with that Hi-Z input is to roll your tone knob back slightly....




-tINY

Old 4 days ago
  #7
Quote:
Originally Posted by KenjiMax View Post
Radial J48 has 600 ohm output impedance, but I chose another DI Box that has 200 ohm output impedance. I want to record electric guitar in my audio interface through DI box. Which impedance is better?
also, how it is that 20$ behringer DI box sounds exactly the same as 200$ Radial J48? Here is comparison test recordings:
https://www.youtube.com/watch?v=VcKvf6bKPbA
It depends on the input impedance of the mic input you're using and whether it's transformer or transformerless. It also depends on the true impedance (NOT DC resistance) of the pickup.The 200 ohm box might work better with some transformer inputs.

Note the emphasis on "might" and "some".

I have no interest in your Youtube "comparison". as YT's lossy encoding and other processing makes any real comparison impossible.
Old 4 days ago
  #8
Quote:
Originally Posted by KenjiMax View Post
Thanks for answer. So there is no such thing as too low output impedance? First I thought that 200 ohm are worse than 600 ohm, since most DI boxes have 600 ohm output.
Also is it true that if I connect DI box to my interface with phantom power on, then I wil not be able to use Ground Lift knob?
If it's an active box running on phantom you'll probably need the ground, yes. It depends on how sophisticated the powering circuit is.

As to the rest of it - it's a pretty complicated subject. I'm considering copying a post from another site I'm on where some real heavies hang out, but it would likely just increase your confusion.
Old 2 days ago
  #9
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Thread Starter
Quote:
Originally Posted by tINY View Post

Well, the 200 ohm one should have just a little less noise (hiss). But, both are sufficiently low to work fine for guitar into nearly any modern mic pre-amp...

As for the quality of the cheaper unit: Guitars are easy. The bandwidth doesn't go very high or low and the inductive nature of the pickups combined with the low signal level are easy for transformers to deal with...

Try plugging a hot analog synth doing bass patches into each box - you'll probably hear a difference there.



-tINY

So if my goal is just to record guitars and basses with passive pickups direcly to audio interface then any DI Box will make job done well? I was choosing between expensive Radial j48 (200$) or cheap Samson MDA1 for 40$. I want as cleanest signal as possible to record and put plugins on it. Or somehow more expensive DI box will have cleaner signal?
Old 1 day ago
  #10
Quote:
Originally Posted by KenjiMax View Post
So if my goal is just to record guitars and basses with passive pickups direcly to audio interface then any DI Box will make job done well? I was choosing between expensive Radial j48 (200$) or cheap Samson MDA1 for 40$. I want as cleanest signal as possible to record and put plugins on it. Or somehow more expensive DI box will have cleaner signal?

The more expensive passive DI will generally have a better transformer. For bass or for harsh electrical environments (like factory floors and aircraft), the better transformers often work better. You need the low-end and the isolation.

For guitar, the limited bandwidth doesn't require as good a transformer - and the studio is usually a noise-free electrical environment.



-tINY

Old 1 day ago
  #11
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Thread Starter
Quote:
Originally Posted by tINY View Post

The more expensive passive DI will generally have a better transformer. For bass or for harsh electrical environments (like factory floors and aircraft), the better transformers often work better. You need the low-end and the isolation.

For guitar, the limited bandwidth doesn't require as good a transformer - and the studio is usually a noise-free electrical environment.



-tINY

But for passive pickups it is better to get an active DI box right?
Old 1 day ago
  #12
Quote:
Originally Posted by KenjiMax View Post
So if my goal is just to record guitars and basses with passive pickups direcly to audio interface then any DI Box will make job done well? I was choosing between expensive Radial j48 (200$) or cheap Samson MDA1 for 40$. I want as cleanest signal as possible to record and put plugins on it. Or somehow more expensive DI box will have cleaner signal?
To begin with, the Radial j48 is not a passive DI, it's active. As such it's suitable for use with pretty much any type of pickup or electronic instrument without any adverse effects on the tone, level, or pickup loading.

The Samson MDA-1 is also an active box. It boasts most of the same general "features" as the Radial. This just goes to show how much good the "feature" lists in sales literature are.

Both boxes use an output transformer for isolation from ground loops and providing a balanced signal. However you could buy two of the Samson boxes for the cost of one of the transformers in the Radial. Good transformers are expensive and they make all the difference to sound quality. Also, the Samson runs on 9 volts internally, while the Radial uses a special internal power supply to boost the rail voltage, which provides much greater headroom. The Radial also uses much higher quality circuitry in general.

If you're actually interested in a passive box, I'd suggest the Radial JDI, which runs around $100.
Old 1 day ago
  #13
Quote:
Originally Posted by KenjiMax View Post
But for passive pickups it is better to get an active DI box right?
With cheap-ass boxes, yes. For quality boxes it's less cut and dried. High quality passive boxes can be very good indeed, and some players prefer them tonally. Low quality passive boxes are fraught with problems.

Since Radial owns Jensen Transformers they are able to sell the JDI for approximately the same money that the transformer in it sells for separately.

It is very tricky to design and build a good passive DI transformer.
Old 1 day ago
  #14
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Just from my experience with microphones, lower is better.
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