The K10

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Important disclaimers:

1. My suggestions were developed to the K10 only. That is the speaker I tested. There is no reason to assume that the same suggestions would be helpful on some other speaker - including the K12. I refuse to speculate. Please do not ask about another device. I do not know the answer.

2. Polarity is determined by testing, not by inspection of the leads connected to the transducers.

3. Correcting reversed polarity is not an automatic net positive. The effect of such a correction must be evaluated by testing before it is clear whether it is beneficial.

4. A notch or dip at the crossover frequency is not indicative of reverse-polarity driver connection. In non-coincident loudspeakers, there must always be amplitude response notches somewhere, regardless of driver polarities.

To summarize: my suggestions are not blanket recommendations for whatever speaker you might be using. If you have a K10, I believe you will find them helpful.
 
BigD1977 said:
With a hard surface, the proximity of the driver to it causes low end reflections,
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For low-frequency sound waves, the term "hard" includes a carpeted floor. The distance between the speaker and a reflective surface and the relative position of the listener together determine the time relationship between the first (direct) arrival and the arrival of the reflection from the surface, which in turn establishes which frequencies are reinforced and which are cancelled.

meaning an increase in perceived bass.
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Not automatically. Depending on the various physical relationships, there can actually be some cancellation of low frequencies.

HOWEVER.... the surface the speaker is resting on may result in low frequency resonances from the vibration of the cabinet, depending on the mass and resonance of the material the surface is made from, and in this case, decoupling can result in lessened perceived bass frequencies.
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Or more. A room boundary surfaces that vibrates sympathetically - far more likely with drywall than with any common flooring material - actually reduces bass via a mechanism known as diaphragmatic absorption.
 
1. Would you expect any significant variations from one K10 to the next?
2. If I wanted to have a speaker evaluated, how would I locate a suitable testing facility, what are the important measurements, how difficult is it to interpret the results in practical terms?

It might be interesting to have this done for another popular speaker, such as the Verve 12Ma. It might be possible to find a testing facility that is local for one of the owners to simplify logistics.
 
Thanks to Jay and Scotts.

FWIW
I returned the K10 I had on rent and decided not to buy it.
I had wanted to get into FRFR, but at the price I'm willing to pay for an FRFR monitor there doesn't seem to be anything out there that I can live with.
The K10 just sounded too much unlike a guitar amp to me, no matter what IR I tried or how I used EQ.
The top-end was particularly annoying.
It's not worth it to me to buy a K10, do the phase mod on the tweeter and then see if it's any better.
But if anybody in Toronto has a K10 that they've done this mod to, I'd love to hear it some time.

FWIW
The Axe sounds way more musical through my old crappy NS10s.
So I can see that with the right monitor playing FRFR *will* be cool.
Just doesn't seem like the K10 is the right monitor.
It was better ultimately than the Yorkville E10P though, to my ears.
For now, I'm sticking to my EVM-12Ls.
 
Jay Mitchell said:
For low-frequency sound waves, the term "hard" includes a carpeted floor. The distance between the speaker and a reflective surface and the relative position of the listener together determine the time relationship between the first (direct) arrival and the arrival of the reflection from the surface, which in turn establishes which frequencies are reinforced and which are cancelled.

Not automatically. Depending on the various physical relationships, there can actually be some cancellation of low frequencies.

Or more. A room boundary surfaces that vibrates sympathetically - far more likely with drywall than with any common flooring material - actually reduces bass via a mechanism known as diaphragmatic absorption.
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Agreed. My point is that dismissing coupling is not accurate, especially when placing the speaker on a riser which may be resonant. Granted, there will be constructive and destructive interference in the acoustic space, which I regarded as outside the original point, which stated that "...there is no such thing as speaker coupling with the ground.". This is false.
 
BigD1977 said:
Agreed. My point is that dismissing coupling is not accurate, especially when placing the speaker on a riser which may be resonant.
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This essentially misses the point, which perhaps Scott did not communicate as accurately as he could have. It is the notion that boundary-loading effects have anything to do with mechanical coupling that is mythology.
 
Jay Mitchell said:
This essentially misses the point, which perhaps Scott did not communicate as accurately as he could have. It is the notion that boundary-loading effects have anything to do with mechanical coupling that is mythology.
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Agreed. Both are separate phenomena, and are frequently confused, one dealing with vibration and the other with panel/airborne acoustic interaction. What was communicated was a dismissal of speaker coupling, which when combined with the good work done on the rest of the post, may lead people to dismiss mechanical coupling altogether.
 
What if Scott's K10 just happened to leave the factory with the tweeter's leads reversed (i.e. a quality control problem) and most K10's have correct phase on the tweeters?
I guess that can't be ruled out unless you test each individual K10.
Or, if you don't like the sound as much after the mod I guess it's easy enough to reverse.
 
Jay, where should I set the Bass switch when I use it as a wedge? Still in the Ext.Sub position + applying the -3db shelf at 700Hz?

Thanx,
Peter
 
joegold said:
What if Scott's K10 just happened to leave the factory with the tweeter's leads reversed (i.e. a quality control problem) and most K10's have correct phase on the tweeters?
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It didn't.

Polarity reversal of one element in a two-way system is a widely employed - but fundamentally flawed - design practice. It is used as a Band-Aid to eliminate a notch in the on-axis amplitude response at crossover. The thinking, such as it is, behind the practice ignores the fact that, in any non-coincident speaker, the inversion doesn't eliminate the notch, it simply moves it to some other set of locations. The practice also ignores the fact that it is often preferable to tolerate a response notch on axis in return for flatter response for a greater number of listeners. It solves nothing - at best it just moves the problem locations - but it always compromises the transient response of a speaker in ways that are audible.

I guess that can't be ruled out
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I am personally acquainted with technical and marketing personnel at QSC. From those acquaintances - and from the fact that the wiring color codes clearly indicated as-intended connection - I can and do rule it out.

Or, if you don't like the sound as much after the mod I guess it's easy enough to reverse.
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Yes.
 
Why would one choose the K10 over the K12? I've been interested in the QSC's but I've always just looked at the K12's. Have I been looking at the wrong speaker? Also, if I am only able to afford 1 speaker at this point - is it still advised to move forward or wait until I can get two?
 
I'm interested in boxes with 10" drivers because of portability.
12" boxes are simply too big and too heavy for the types of things I'll be using it for.
But I'm not a metal player who needs a thundering back-line on stage with me.
 
brianoc said:
Why would one choose the K10 over the K12? I've been interested in the QSC's but I've always just looked at the K12's. Have I been looking at the wrong speaker? Also, if I am only able to afford 1 speaker at this point - is it still advised to move forward or wait until I can get two?
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Horses for courses. You should get the 12 if you need the added power of the 12. If you don't, get the the 10 or the 8. The important thing is to get the one that meets your needs easily. Don't get a K10 if you know you'll need to push it near it's max to meet your needs. If you push these too far, they no longer operate as intended and you can forget clarity and flat response.

D
 
dk_ace said:
Horses for courses. You should get the 12 if you need the added power of the 12. If you don't, get the the 10 or the 8. The important thing is to get the one that meets your needs easily. Don't get a K10 if you know you'll need to push it near it's max to meet your needs. If you push these too far, they no longer operate as intended and you can forget clarity and flat response.

D
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Power is the same. They're all 1000w. The differences are going to be in size, weight, and freq. response.
 
I would love to know similar information regarding the FBT Verve 12ma, but I lack the knowledge and experience to do it myself. I'll have to google around a bit to see if anyone has looked into that speaker. I know one of the users here created an IR to flatten out the FBT Verve, but his unit is in for factory repair, so I'm not sure it'd be the best idea for me to use that IR. The other problem with looking at other people's tests on google is putting the same trust in accuracy in their tests as you would with Jay's tests.

Which basically means I should just practice my ability to play guitar instead of messing with it. :)
 
bkrumme said:
Jay, if it's not too much to ask, how would one test to determine polarity?
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My guess is that one measures the impulse or step response of the low and high freq drivers and if the initial response heads in a different direction than the other driver, then the polarity of one of the two is swapped.
 
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