DI Box and other basic questions.

[timwat]

Agreed there is always a "best practice" (which sometimes feels like an excuse to sell you gear), and the real world.

 

I still remember Eddie Jobson touring UK, running the entire rig of multiple VAX77 controllers into a MacBook Pro, having a redundant MacBook Pro, and using the headphone out of both laptops for all sound to FOH.

 

And that tour sounded just glorious. 

[Reezekeys]

The MacBook Pro's headphone port has had very decent audio specs for a long time. I'm not sure what year/model these are from, but I think it's typical of the range. This is copied from an Apple support page:

 

Maximum output voltage: 2 VRMS (+8.24 dBu)
Output impedance: < 24 Ω
Frequency response: 20 Hz to 20 kHz, +0.5 dB/-3 dB
Signal-to-noise ratio (SNR): > 90 dB
Total harmonic distortion + noise (THD+N): < -80 dB (0.01%)
Channel separation: > 75 dB

 

The new M1 MBPs tout a redesigned headphone amplifier capable of driving high impedance headphones, so the specs listed above may not apply - but seeing as the change is being sold as a way to connect expensive audiophile headphones (which presumably have higher impedances), I'm guessing the overall specs are the same if not better.

 

I just checked and my QSC K8's input impedance is 20K. So, I'm obviously driving a higher-impedance input from a low impedance output. Not sure what that means in terms of sound quality, but I've been happily doing it this way on four different Mac laptops starting with a 500Mhz Titanium G4 in 2001. That's over twenty years of "doing it wrong", I suppose! 🙂 

[KuruPrionz]

I've taken a different path, no dings on Radial and their excellent products. 

My favorite DI is the Tech 21 Q-Strip. It's an active DI that runs on either a 9v battery or phantom power if the lines from the mixer aren't too long. 

Straight DI with a parallel output on the panel with the input, your choice of XLR mic or line or you can go 1/4" TRS if you're running into an onstage mixer that will accept that (I use that to record sometimes, different topic). There are buttons with attenuation so you can switch between using mic or line level output and also a switch to allow phantom power or use the battery. 

4 great sounding tone controls - Bass, quasi parametric Low and High Mids and Treble. Whether you need a small tweak or a bit larger shift in EQ, the bands have a smooth curve so nothing sounds spikey or obnoxious. Very low noise, built to last. 

 

Since "one is none and two is one" you could pick up a used Whirlwind  IMP 2 DI for a few bucks as a backup. It's way better than not having a DI. Cheap, sounds pretty OK and virtually indestructible. I've used it a couple of times but it's sort of a security blanket, small, light, cheap and reliable. 

[Al Coda]

8 hours ago, Reezekeys said:

I've never heard a headphone output called "line level" - it's always hotter. Try connecting typical headphones to a -10 or even +4 signal - I don't think you're going to get much volume.

 

On my Lenovo workstation laptop I use for VST, the 1/8" TS output is a combined phones/ line output.

"Line" is -10dB.

Obviously, Windows 10 autodetects headphones connected,- and there are audio settings available specifying what´s connected,- active speakers OR headphones.

Currently here @home and using a single cable, I go directly into the 1/8" TS input of my mobile pair of Presonus active "Studio" monitors I´ve set up in the living room and have the A-800 Pro connected to do some homework.

No hum, no hiss, plenty of power for that purpose.

When I wanted the balanced TRS jacks on the back,- a line level shifter would be helpfull,- a DI box wouldn´t,- just because there´s no MIC INPUT available.

In my former post above I didn´t say headphones level is -10dB,- instead I said, consumer line level on 1/8" TS and/or cinch output is -10dB,- and it IS.

And keyboards´ unbalanced TS line outputs are typically -10dB also,- and I´ve seen -20dB too in the past.

 

According to the damn mic-level output DIs being designed to convert a low level guitar´s or bass´ electromagnetic pickup signal into a balanced mic level signal/ 600 Ohm load,- it´s backward usage when it comes to modern keyboard instruments and modern PA gear.

In fact, I cannot remember when I´ve seen an analog FOH console providing Mic-Inputs only and combined w/ an analog stagebox and multicore for the last time.

It´s all digital since what ? 2 decades ?

Every digital FOH console and digital stage box (which is nothing else than a complete mixer w/o haptics and screen) offers balanced combined XLR/TRS Mic-/LIne inputs,- the signals traveling thru CAT5 etc..

So, it´s not only unnecessary,- it´s idiotic bringing down any hot line signal, unbalanced or balanced, down to mic level.

 

And just only because "old fart" and "experienced" FOH "engineer" does the same since half of a century or more,- I don´t accept he does.

His and his hands´ "experience" and "engineering" is typically setting up a PA w/ console and siderack in mono, stack tube amp heads and 4x12 cabs, use unbalanced guitar/instrument cables into amp and speaker cable into cab, then place a mic and plug into analog stagebox.

And they always hate electronic keyboards and technically skilled keyboardplayers recognizing how dumb they are.

He´s a service provider and not my boss,- last but no least because he doesn´t pay me.

It´s my gear and I tell how to deal with,- period.

When they don´t like, they are free renting everything and I leave mine @home.

Fine,- another reason not to invest in DI boxes !

 

 

A.C.

[Julius D Majestic Studios]

Here is a link to the thread I referenced.

 

https://forums.musicplayer.com/topic/182647-radial-dis-how-do-you-feel-about-them-studiolive-or-dis-in-general/#comment-2903417

[MotiDave]

On 10/5/2022 at 5:40 AM, Reezekeys said:

 

Of course you must have a stereo DI box to get a line from a stereo source! This is an actual sound company still in business?

I’ve played lots of festivals where all they have is a big stack of mono DIs - they just connect two to my stereo outputs.  

 

I’m like the rest here - I’ve never had a festival say they didn’t have DIs or get annoyed to connect stereo.  They never object to stereo either.  Only time I get asked to play mono is the smallest of shitty dive bars or when I want to plug into the lead singer’s crap home PA in a garage lol.  Even small dive bars, if they have a sound engineer he’ll almost always connect stereo.

 

I always bring my own DIs.  I have a Radial D2 stereo and a Samson that can combine stereo in’s to mono XLR while passing thru the two stereo to monitors (if house insists on mono FOH but I have stereo stage monitors).

 

Key-Largo looks bitchin, i don’t run multiple keyboards or thats what I’d get.

 

OP’s starting of this tread talked about more than one keyboard.  In that case I recommend he have a small mixer.  Key-Largo isn’t the only option but it looks really cool with tiny footprint and lots of channels - plus you get Radial’s known quality circuitry and DI protection.  But OP could use any of a number of small 4 channel mixers if preferred.  FOH MAY get annoyed with a keyboardist who expects them to run 3 different stereo keyboards (6 channels both in FOH as well as their monitor system.  Thats expecting too much. 

 

Mix yourself down to two stereo outs to FOH and you should be fine.

ALWAYS have a DI between your boards and FOH.  thats why I always have my own in gig bag just in case.  But if he has his own, i leave mine stored in the bag - once less thing to pack up and don’t have to worry about stage crew taking it on accident.

[Outkaster]

As a follow up.  I ended up with a gig at a small venue where the soundguy didn't have enough boxes.  I picked these up yesterday just in case the situation happens again:

 

https://www.sweetwater.com/store/detail/IMP2--whirlwind-imp-2-1-channel-passive-instrument-direct-box