QSC K10 Polarity Modification

count_chocolat

count_chocolat

Experienced
I have a question about this mod. I use the QSC K10 as a monitor coming from the board (Aux out), I usually have vocals & guitar coming though it. Not understanding most of the technical verbage and charts in the sticky in this forum, how will the proposed modification affect or improve what I will be hearing on stage?
 
If both your vocals and guitar are coming from the same Aux send, my guess is that there is some EQ on the signal so that your vocals won’t feedback. This may or may not be affecting your guitar signal in a way that you won’t like. Some people don’t mind this. Depending on the circumstances, I can live with it.

But, there is an advantage with the K series, since the speaker has 2 inputs. If I were you, I would run your second output from the Axe Fx right into the second input of the K-10. Your guitar signal will be bypassing your vocal EQ and be completely flat. Plus you’ll have immediate control over your guitars stage volume without messing with FOH. I was doing this when I was using the K-10.
 
count_chocolat said:
I have a question about this mod. I use the QSC K10 as a monitor coming from the board (Aux out), I usually have vocals & guitar coming though it. Not understanding most of the technical verbage and charts in the sticky in this forum, how will the proposed modification affect or improve what I will be hearing on stage?
Click to expand...

Per my understanding, with this Mod, your speaker should be 'closer' to being flat.

This is thought to be optimal no matter what you are running through it.
 
It's not just a flatter frequency response (when standing off-axis from the tweeter), it's also a more faithful dynamic response in the high end due to the tweeter being in phase with the woofer.
 
count_chocolat said:
I have a question about this mod. I use the QSC K10 as a monitor coming from the board (Aux out), I usually have vocals & guitar coming though it. Not understanding most of the technical verbage and charts in the sticky in this forum, how will the proposed modification affect or improve what I will be hearing on stage?
Click to expand...

Basically, the idea behind this mod is incorrect. Look at the graphs, after applying the mod you have a 30db dip in the midrange response! If you want a 30db dip in your midrange response, there are other ways to acheive it, but generally it is not a good idea. Whoever suggested this mod fails to understand the basic differences betweeen electrical and acoustic phase .. and has seemingly forgotten that the HF and bass units are not in the same vertical plane. Theres a reason the phase was reversed electrically, and that is to correct the acoustic phase at the crossover point ...

In short, it was fine the way it was designed, and built. This mod will actually make a large hole in the mid range and make an acoustic phase error at the crossover point. If you want to spend some money, put a digital delay in the bass circuit and bi-amp it which will sort out the impulse response and the phasing ... if you just want it to work correctly at minimal cost, just leave it as the manufacturer made it.
 
CrazyTrainer said:
Whoever suggested this mod fails to understand the basic differences betweeen electrical and acoustic phase .. and has seemingly forgotten that the HF and bass units are not in the same vertical plane. Theres a reason the phase was reversed electrically, and that is to correct the acoustic phase at the crossover point ...
Click to expand...

Well....it's a pretty reputable source.
Link shows the detail behind the suggestion:

http://forum.fractalaudio.com/amps-cabs/37266-qcs-k10-tips.html
 
CrazyTrainer said:
Whoever suggested this mod fails to understand the basic differences betweeen electrical and acoustic phase .. and has seemingly forgotten that the HF and bass units are not in the same vertical plane. Theres a reason the phase was reversed electrically, and that is to correct the acoustic phase at the crossover point ...
Click to expand...
Somehow I doubt that Jay doesn't understand the difference between electrical and acoustic phase, but he's not here to defend himself.
In short, it was fine the way it was designed, and built. This mod will actually make a large hole in the mid range and make an acoustic phase error at the crossover point. If you want to spend some money, put a digital delay in the bass circuit and bi-amp it which will sort out the impulse response and the phasing ... if you just want it to work correctly at minimal cost, just leave it as the manufacturer made it.
Click to expand...
If I'm reading the graphs right, with the mod, if you position yourself +10 degrees off-axis, the response is essentially flat, plus the tweeter and woofer signals are in phase. What I perceived after doing the mod was an increased directness to my pick attack. Before it seemed to get swallowed up at odd moments, probably depending on where I was standing. YMMV.
 
BBN said:
Well....it's a pretty reputable source.
Link shows the detail behind the suggestion:

http://forum.fractalaudio.com/amps-cabs/37266-qcs-k10-tips.html
Click to expand...


Link shows a 20db deep notch at 2KHz on axis ... if thats the effect you are looking for, be my guest.

As I said, the only way to really align the two units is to use a delay in the bass, the compromise is to invert the phase on the tweeter, not an ideal solution, but very very commonly used ... putting the tweeter phase back "correct" may improve the IR, but will give you that nasty on-axis hole ... to my eye, the modified graph with the hole and the corresponding phase error look worse not better.
 
You must log in or register to reply here.
Back
Top Bottom