Using Headphone Jack As Output?

[chatfd]

Just a thought, using my QSC, I've seldom had a volume issue. I usual go thru a small mixer then to the QSC-K-12.
I Have to be careful I don't blow my own ears off. And at times, the guitarist has asked me to turn down!

I credit the QSC!!

Also, where I've volume issue, it is with some of the samples. SELDOM, if ever, with pianos or the B3. But a few if those samples need a boost! Those samples don't stay on my electro long!

[Chilitopper]

Since am using 2 QSC 10's for monitors, my plan is to use a splitter out of the headphones jack to give me two mono channels to run to each QSC so I'll have a true stereo field in the monitors. The whole reason to use the headphone out and not the line outs is to include whatever I have plugged into the monitor in jack on the back of the Electro. According to the manual, the monitor in signal only goes to the headphone jack and not line outs.

I use monitor in for mp3 players both live and to rehearse.

I'm also wondering if I can use the monitor in for a second keyboard. I'd have to reduce that keyboards outputs to a mini plug. I guess I'm trying to avoid using a mixer and make the setup simple. Does reducing a signal to a miniplug affect the quality of the audio? And is it still stereo?

[pablomastodon]

Hi Chili,

Using the headphone output will necessarily affect the quality of your sound in an adverse way. This effect may not rise to the level of being unusable, but your QSC's inputs are not designed to accept signal level being output by the Nord's headphone outs.

Reducing an instrument's 1/4" output to an 1/8" plug will not necessarily affect the quality of the audio (although in my experience 1/8" connectors are lots more finicky and sometimes cause problems). However, using the mp3 player input circuit as a keyboard mixer will certainly affect your sound quality.

The impulse to want to connect things in that way is understandable, but counterproductive. Why spend good money on a keyboard for its high quality sound and then instantly degrade that sound quality by doing these things to it? A quality mixer if the best way to go, but if you're not yet ready to cough up that price tag (my Ashly is ~$400), you can always get one of those cheapo Behringers and work it for a year or two (which is about as long as it will last before beginning to fail in my experience), by which time your keyboard rig will have earned you enough to afford something better.

Just my two centavos...

Pablo

[Chilitopper]

Thanks for the quick answer Pablo. That's good info and makes sense. I'll have to get a small mixer mostly to use with my second keyboard. Or maybe a DI box that will accept a stereo line input as well as a second mono signal. Then I could send the DI outputs into the QSC's. Anything wrong with that idea?

[pablomastodon]

There are multi-channel DIs out there, but I'm not aware of one which mixes signals. I think I might have seen some powered speakers which actually have multi-channel inputs, but I don't recall who made them. Also, I don't guess you're trying to change out your QSCs (which are, by most accounts, pretty nice).

My Ashly is no longer in use (and I don't mind to part with it -- 8 stereos channels in 1U) since I have migrated to Presonus. I got the 16.0.2 a year ago and have gone so head over heels that I just added 1818VSL. Eight mono channels (drag) in 1U and you need a computer to drive it (also drag), but it gives HUGE EQ, F/X, compression, etc. possibilities/flexibilities.

Small mixer is way to go.

Pablo

[pterm]

Using the headphone output will necessarily affect the quality of your sound in an adverse way. This effect may not rise to the level of being unusable, but your QSC's inputs are not designed to accept signal level being output by the Nord's headphone outs.
Pablo

Pablo, I want to understand this better, but I don't know how you reached this conclusion:

I am uncertain how the headphone output necessarily affects the quality of the sound adversely: I compared the gain stages of the output amplifiers from the Electro 2 Service manual schematics (http://www.workhousepoets.com/NE2%20Ser ... matics.pdf). These schematics show that the Line Out amplifier and and Headphone Out amplifier share a common source. That is, the Left channel goes to both Headphone amplifier and the Line Out amplifier (and similar for Right channel) . I calculated that the Headphone amplifier provides about 2.3X the gain of the Line Out amplifier. So, the Headphone voltage should be no more than 2.3X the Line Out voltage into the same input impedance.

The K-Series specification (http://www.qscaudio.com/products/speake ... ations.php) shows RCA-Jack input impedance of 10Kohm. Since this is a resistive load, it should only affect signal level, but not the frequency response of the Headphone Amplifier when connected to the load (the K-series, in this case).

Subsequently, the only way I can think of to introduce distortion is too exceed the input voltage range of the input device, causing clipping of the signal (introduces harmonic distortion).

Now, the K-series specifications don't specify their permitted input signal levels explicitly, so looking at wikipedia (http://en.wikipedia.org/wiki/Line_level#Nominal_levels), I see two different definitions for "Line Level":

Professional audio +4 dBu =1.736 Vpeak
Consumer audio -10 dBV =0.447 Vpeak

If we assume that the QSC supports Professional Line Level, then it would be safe with Consumer Line Level outs. If Nord specifies Consumer Line Level, then even with 2.3X more gain in the headphone path, it could be safe.
THIS IS A HUGE ASSUMPTION: CONNECTING YOUR HEADPHONE OUT TO LINE-IN RISKS DAMAGING YOUR NORD and WHAT YOU CONNECT IT TO. DO SO AT YOUR PERIL!

If you can shed some light on the cause or mechanism of the degradation of sound quality I'd appreciate it. I enjoy noodling through the electronics, but my understanding of pro audio is lacking.
Thanks,
Peter

Look, let me go back in there and face the peril.

No, it's too perilous.

[pablomastodon]

Hi Peter,

"the only way I can think of to introduce distortion is too exceed the input voltage range of the input device, causing clipping of the signal (introduces harmonic distortion)"

I think that pretty much sums it up. From that point your post ventures off to make some assumptions which may or may not be valid. Overdriving an input is likely to cause distortion. With special care it may be possible to run that way without overdriving, but many less sophisticated users may not be sensitive to this. Better to not even open that door and eliminate the possibility entirely, and to use things in a manner consistent with the purpose for which they were designed.

Pablo

[mjbrands]

What you say makes sense. Yet I've also seen situations where I would get a deteriorated signal via the headphone when compared to a line-out; in both cases I had a standard PC sound card connected. This was years ago and not on a Nord (or other synth for that matter).

Now I may have just been driving the head phone output to 'hot'; I didn't have a scope back then I can can imagine that if I'd used a scope to match the levels on both outputs that I'd have gotten exactly the same quality signal.

Now that I'm thinking about it; would the noise floor me the same on both? In both cases noise coming into the amplifier would be reproduces, but wouldn't the amp itself also contribute slightly, regardless of volume/gain level? With the headphone output, wouldn't that have a higher amplitude?

Look, let me go back in there and face the peril.

No, it's too perilous.

Ha ha, that made me laugh.

[mfish]

I usually don't respond but thought I might add my two cents. I wanted to run a separate monitor system from the house and talked with several technicians on this subject. The quick solution that I've been using for the last year on an Electro 3 is to run the DI from the line outputs to the house and then run a headphone stereo splitter cable from the headphone output into a radial stage bug DI into a EV ZXA90 mic input. The two reasons for this is, plugging the Electro directly into an EV is just too low volume and running the Electro in stereo gives it a little more fullness. The Stagebug sums the stereo headphone signal and allows me enough extra gain to drive the EV. I was amazed the first time we tried this because it didn't add any noise (EV already had a little hiss) and the EV sounded very natural and loud. This is the perfect setup for me because I can now throw the electro gig bag and EV gig bag over my shoulders and show up for rehearsal. I wanted my own monitor system because the pianos through the House JBL floor monitors sounded harsh and the EV at 19lbs is light enough to carry to all the performances. I've been looking for the perfect sound system and I know a lot of my friends use the QSC K10s but to my ears the EVs are more natural sounding for acoustic piano patches and way lighter. This setup was more for the smaller gigs when I wanted the best piano sound and the ability to carry everything in one trip from the car, because on large gigs I have to bring my Korg Kronos and Roland RD700 to cover all the parts, so I use a Mackie mixer. P.S. according to Radial, plugging into the Stagebug will give the sound a warm tube like quality which although very slight does make a difference when playing loud. Just my two cents.

[anotherscott]

I know a lot of my friends use the QSC K10s but to my ears the EVs are more natural sounding for acoustic piano patches and way lighter.

I agree, the EV is great. I A/B'd it against the QSC K8 and had the same reaction, pianos sounds much more natural through the EV (though the QSC will go louder, and has more input flexibility). I liked the lighter weight, and that it can naturally be used in floor wedge position if desired as well, which the K8 cannot (but the K10 can).