QSC Kseries Freq Response Charts

[larico]

I came upon some frequency response charts for the K and KW series speakers from QSC. Since there are quite a few of us that use these, I thought I would post where I saw the info.

 

http://forum.qscaudio.com/forum/viewtopic.php?f=4&t=3548&sid=d755a1382fad4dc6e3c53ee9d6577197

 

If this is old news to y'all, forgive me. I just got a couple of K12s around Thanksgiving time. Been looking around for info on them. They were an unexpected gift from my wife and I am trying to get familiar with them.

 

I realize the data shown on the charts was probably gathered under lab conditions with specialized equipment.

 

I have a question - is there a practical way to use the info on the charts to make a keyboard rig sound better?

 

Richard

 

 

[ksoper]

 

I realize the data shown on the charts was probably gathered under lab conditions with specialized equipment.

 

I have a question - is there a practical way to use the info on the charts to make a keyboard rig sound better?

 

Richard

 

 

My gut feeling is that specs generated in a chamber are just that--specs. They have little bearing on what your ears will tell you as you move the cabinet from room to room. What will make your keyboard rig sound better is to make sure that there are no weak links in the signal chain, from the instrument to the effects, to the mixer, to the amplifier, etc.

 

And then you must not suck. That'll make any keyboard rig sound better.

[JeffLearman]

I don't believe the K8 and K10 graphs could be so similar -- they look *identical* to me. I suspect a mixup there.

 

In any case, they look reasonably flat, which is great. I'd agree that your ears would be the best judge, but for K8 or K10 (whichever that graph is really for) I'd consider a 3dB boost at 8K, with fairly narrow Q.

 

Another thing to consider is that response may vary somewhat from speaker to speaker. You're better off measuring your own, which you can do with an inexpensive calibration mic, a noise generator, and any DAW with a good FFT plugin. There are also programs like RoomEQ to help the process.

 

Q: If calibration mics are flat and inexpensive, why don't we use them for recording?

A: Transient response stinks.

[MoodyBluesKeys]

And then you must not suck. That'll make any keyboard rig sound better.

 

QOTW Material !!!

[kanker.]

I don't believe the K8 and K10 graphs could be so similar -- they look *identical* to me. I suspect a mixup there.

Yeah, I looked at them from point to point and they are identical, which is basically impossible. Musta been a mix up, although looking at that curve compared to the K12 curve, I wouldn't expect a very large deviation from the two curves they did post for the K series

[larico]

Yep, I was just curious. Like I posted, was wondering if there is a "practical" way to use the info. For instance, I have a dual 15 band EQ between my mixer and speakers. I could look at the chart, pick out points that deviate from flat response the most and boost or cut accordingly. Then, listen to my gear and see if it improved the sound at all.

 

Not an audio engineer, but I would think these charts would change a bit (or a lot) just moving the speaker(s) from one room or club or stage to another. Even small changes in how you set up the test gear could change those charts significantly.

 

I will ultimately let my ears tell me what sounds best and adjust accordingly. Just wondered if the data was a something that could be used to make things a little better as a starting point to setting up a keyboard system?

 

Richard

[mate stubb]

All the data tells you is how flat the response is in an ideal echoless environment, which translates to how much EQ you need to apply in a real room.

 

Generally, a flatter response is good because your EQ only has to overcome room deficiencies, not room AND speaker response deficiencies.

 

It's not too surprising that the 2 cabs would be very close in response in the treble end - identical amps and treble drivers and all that.

 

But I would expect the bass response to be noticeably different.

[Jazzwee]

It didn't look identical. There were differences in the low end. But suprisingly, not that much, which is very interesting.

[kanker.]

It didn't look identical. There were differences in the low end. But suprisingly, not that much, which is very interesting.

Look at the K8 and K10 charts again - they are exactly the same, point to point. Again, it's probably just an error on their part.

[Jazzwee]

Yeah - you're right on K8 and K10. Just goes to show that you might as well get the K8 if you're looking at K10. Or skip to K12. Either that or it's an error.

[Joe Muscara]

I'd like to argue that maybe it is because the measurements were taken at a certain distance and angle from each of the speakers and the real-world difference is in the dispersion, but I can't. There's just No Way the curves would be exactly the same. Similar, maybe, but not identical. Look at how similar, yet slightly different the K12 curve is. I would expect K8/K10 to vary like that.

 

This brings me to my next problem with these curves. Many of us know one of the major differences between the three models is the dispersion, yet that is not shown here. I would think you'd want a response vs. angle chart similar to what you see for a mic polar pattern, with a different line for straight on and two or three angles.

[J. Dan]

I would bet that even if you measured 2 different K10's, you'd see variation in their responses...there is a wide tolerance in speaker manufacturing.

[JeffLearman]

I would bet that even if you measured 2 different K10's, you'd see variation in their responses...there is a wide tolerance in speaker manufacturing.

+1

 

I wonder whether the posted graph is for the K10 or K8, and I'd bet it's from the K10. The difference in bass cutoff is remarkably low between K10 and K12 but still measureable -- too small a difference to be from the K8. I'd expect even more difference between K10 and K8.