Di Box or Preamp

[Lenny13]

Hi,

I just received my Saffire Pro 24 DSP and I must tell that I love it. Bought it for the nice preamp and the VRM feature.

I have a slight problem : I plug my guitar directly into the interface and select the Inst input inside the Saffire MixControl. Problem is that I must set the gain to 1 or 0 to prevent from clipping. And even with that, I don't have enough headroom. I have two Dimarzio on my guitar : One Evolution and a Steve Special.
I read somewhere that it is quite common with this interface.

Will a DI Box fix my problem ? Which one should I choose ?
I also read about the ART Tube Mp Studio. I could have then a cheap valve preamp with this solution but will Art Tube works as a preamp and a DI Box ?

Thanks.

 

[ArthurD]

Use the pad switch or buy a real DI (radial, countryman, etc)

 

[Lenny13]

Thank you. Unfortunatly there is no pad switch on the interface. Maybe a Radial will do the job.

 

[Scottxx]

I never had a problem like that. But I like to use a cheap Behringer MIC200 preamp with a changed valve. It adds that lost valve tone for use with any amp sim. The sound is great.

 

[Lenny13]

Thank you Scottxx. Someone said on a different forum that it might help to lower the pickups. I will try that first Do you have a Saffire Pro 24 DSP too ? If yes, what pickups do you use and how much is the gain when you plug your guitar without the preamp ?

 

[deLuther]

Art Tube MP clones (like mentioned Behringer) only add "tube" mudness, they use valve on low voltage, so it mostly only looks cool, recorded DIs can suffer from boosted sub lows, so you need some high-pass filter afterwards... Swapped my Art Tube for loacally made mic/line/inst preamp, there was significant improvement, but there no international alternatives. Have some old DI samples of art and my pre. One good point of Art - it can handle large input level, but you should carefully set input gain to prevent internal clipping, than you can set output gain to needed level. Behringes clones handle lower input levels.

 

[TheWinterSnow]

There was a thread not too long ago that had the same problem. Designers of instrument input interfaces are designing these circuits with the old school assumption that the hottest pickups put out 100mV at best. That is about -18dBu. The reality most high output passive and active pickups put out way more than that, orders of magnitude greater, try as high as +12dBu. Instrument inputs on interfaces weren't designed to do handle that.

The professional, or more accurately, the industry standard because it still is not fully correct electrically is to use a DI which steps the voltage down to mic level, or realistically somewhat close to mic signal so that you can plug into a mic preamp and use that to get your line level signal. In the case of an onboard preamp on the saffire the DI would just go into the a mic channel and that would be the end of the day. You set the gain on the mic preamp to adjust your signal strength and you have more wiggle room to get proper tracking levels.

There is one problem though. There is a tradeoff when it comes to using a transformer based DI, they cannot stepdown enough to get a proper load on the pickup. In passive pickups that meas a shift in frequency response, you loose highs. If you were to get a stepdown low enough you loose even more highs and some bass as well. The typical solution is to go to an active DI because they have the same effect on passives and actives and closely approximate what a guitar amp would act on a pickup.

In the quality range of DI's you have Countryman Type 85, Little Labs Redeye, Radial J48 and the less known Corvus Audio DI+.

 

[deLuther]

In the quality range of DI's you have Countryman Type 85, Little Labs Redeye, Radial J48 and the less known Corvus Audio DI+.

Russians just use Digilab SPM-100, for around of 150$ you get Mic/Line/Instrument preamp with low THD even at +22 dbu level because of +/-15 V bipolar power supply, schematics is very simple and it works.
In case of classic DI boxes result is also depends on quality of mic pre.
One example is Presonus 44VSL it has very good line inputs, but crappy preamp inputs, so using some kind of instrument preamp (i.e. without level reduction to mic level) into line inputs can give significantly better results.

 

[Lenny13]

Thanks to both of you. Planning to get a Radial J48 soon.

 

[Lenny13]

Quick update. Just received my Radial J48. Same problem Input Gain on 1 and not enough headroom. There is a 15dB Pad. When activated, I can crank up the input gain to 6. Just a question : when I turn the 15dB pad on, do I get the same quality signal as with the pad turned off ? Sorry for the noob questions guys.

 

[Uros]

I have 24 DSP, a sevenstring guitar (so higher output comparing to 6string) and high output humbacker (SD Distortion), and my input gain is set at ~9 o'clock, and I get no clipping (highest peaks are close to -6 dBFS). I have Redeye, but don't use it.

You should have similar quality with Radial J48, since it's an active DI Box. There shouldn't be any frequency response change. Try it out yourself.

 

[Lenny13]

Thanks for the reply. Do you plug your guitar directly into the 24 DSP ? Do you select Inst or Line ?

 

[Uros]

Instrument input of course. Evolution is hotter pickup comparing to Distortion though, so I guess that you will have to use the pad switch on J48. But don't sweat it, it's there for a reason.

 

[Lenny13]

Thank you so much.

 

[Uros]

;-)

 

[deLuther]

Pad switch on most DI boxes reduces impedance, but J48 seems does not have such Pad behaviour, i.e. impedance stays the same 220k (too low, for my opinion).
Still Radial claims that it has +10 dbu maximum input level:
http://radialeng.com/j48-specs.php