QSC K8 Audition & Some Personal Thoughts

[BoB/335]

Originally Posted by geokie8

A comparable 80% increase in the JBL's power would be 396 watts (220 X .8 + 220); therefore, the JBL is definitely a more efficient speaker (i.e., if you put a 500 watt amp in the JBL, theoretically you'd end up with a Max SPL rating closer to 133 dB).

Footnote: The K8 is rated 127 dB, and there will obviously be a falloff in the lower frequencies; however, JBL doesn't make an 8" speaker in that series for comparison.

I'm NOT a techie so I probably have NO IDEA what I am talking about.
I don't think you can look at the comparison in that way (by hyperthetically adding 80% increase in power to the formula) I think you have to take it for what ir IS.
Max SPL of 121 dB - Max SPL of 129 dB

Also there is always a falloff in the lower frequencies with every speaker. The K8 claims it goes down to 66Hz at -6dB. Would it not be safe to say that this speaker will cover the low frequencies of an acoustic guitar? (What does the BagAmp claim?)

[Joseph Hanna]

Originally Posted by Bobby1note

I would challenge anyone to find the actual specs saying "1000w". Not the marketing blurb, but the actual specs.

Bob

Those ARE the actual specs. QSC like many companies are using "Class D & E" Digital Switching power amp sections that provide (here to for) unheard of output spec levels.

That said it's VERY difficult to compare output specs and MUCH more importantly compare sonic impact between Digital Class D amps and Analog A or A/B designs.

Comparing specs between two like and similar products, say for instance, a Crest Class A Power Amp and an Ashley Class A Power Amp has some (albeit limited) sonic value.

Comparing the specs of a new design Class D Digital switching Amp to that of Analog Amp is a road to madness. Absolutely sonically meaningless.

[kramster]

Very good points Mr. Hanna. That whole apples and bananas thing.

[BoB/335]

Originally Posted by tdrake

Just thinking out loud a bit about the usefulness of a really loud, ultra-portable/lightweight, small (8-10") cab for acoustic musicians....

When I need to play to a very large crowd (one that would call for lots of volume) I find that someone else provides the PA, and that PA is very large.

When I play an intimate setting requiring high fidelity for a close-listening audience, I find that a very small amount of amplification goes a long ways, and the less the better because, after all, they showed up to listen to *acoustic* music.

When I play a "normal" show the venue is loud because people are having a good time, and although they'll quiet down for half the toons, they're still there to be entertained rather than be awed by high fidelity.

For all of these reasons, I can really see the benefit of a Solo Amp, Bag Amp or Bose system, though the first two make more economical sense to my personal approach to gear and performance...but I can't really see why I'd need to buy a really expensive small/highly portable, 1000 watt powered speaker.

I mean, if it's a big show, take a big speaker, and if it's a big show, certainly portability isn't a concern.

In other words, this debate about this product seems more academic than applicable to the types of music and shows the acoustic musicians I know really tend to play.

Just my thoughts.

td

I've been dabbling in PA for a few years now with a much larger system. Even though I still don't really know what I am doing, I have found that there is a definite correlation between a pleasing sound and power. The more power, the more clean headroom, the less ear fatigue, the more pleasing the sound is. I know that as a fact using JBL MPro415's with what would be called "adequate power" and driving them with Program Rating. The whole tone of the speaker is different with more power.

I am NOT saying that a powered speaker with more power will sound better than a different speaker with less power. There are design and component values in the equation.

[Joseph Hanna]

Originally Posted by BoB/335

Max SPL of 121 dB - Max SPL of 129 dB

The first thing that comes to mind here is I'd hate to be the poor guy standing in front of a two-way 8'' speaker system at 129dB.

I not sure what ANYONE could get out of this spec especially if they're were attempting to apply this to anything that happens in the real world of club playing.

I had a boss once that could scream at me at 129dB. There were NO redeeming sonic benefits from that talent.

[Joseph Hanna]

Originally Posted by BoB/335

I've been dabbling in PA for a few years now with a much larger system. Even though I still don't really know what I am doing, I have found that there is a definite correlation between a pleasing sound and power. The more power, the more clean headroom, the less ear fatigue, the more pleasing the sound is.

Well......yes and no. Again when comparing well designed, like and similar, power amps the equation of more power=more headroom=less distortion holds up fairly well. Although even then it CAN be misleading as some analog amps are MUCH more efficient than others.

Expecting that equation to hold up when comparing (under designed analog) or Digital Power Amps with well built Analog Power Amps is pointless.

I'm willing to put my money in a 300 watt Crest Power Amp any day, all day, endlessly before I'd EVER entertain some of the cheap, light weight 1000 watt Digital Amps.

[geokie8]

Originally Posted by BoB/335

I don't think you can look at the comparison in that way (by hyperthetically adding 80% increase in power to the formula) I think you have to take it for what ir IS.
Max SPL of 121 dB - Max SPL of 129 dB

The 80% figure does come from comparing the Max SPL (i.e., the K10's output is almost twice as loud as the 510 -- but closer to 80%). The rest was theoretical (hence my use of the term "theoretically)."

FWIW, I was only comparing the QSC to the JBL amp -- precisely because they are similar (both class D digital amps, same size, and used for roughly the same purpose).

In addition, Max SPL ratings are taken at 1 meter's distance and there is a volume dropoff depending upon where the speaker is placed (and no, I wouldn't want to be standing 3 feet away from 129 dB -- or 121 for that matter).

geokie8

[geokie8]

Originally Posted by BoB/335

Also there is always a falloff in the lower frequencies with every speaker. The K8 claims it goes down to 66Hz at -6dB. Would it not be safe to say that this speaker will cover the low frequencies of an acoustic guitar? (What does the BagAmp claim?)

I've read somewhere that the low E of an acoustic guitar is around 82 Kz.

To my knowledge, there are no specs on the BagAmp; however, representatives have stated that it goes down to 60 Hz (in a personal email to me and posted on AGF elsewhere). Irrespective of the veracity of the statement, I really think the BagAmp's response for an acoustic guitar would be fine -- and buy into the statement that keyboard players and bass players probably need to add the sub.

[SpruceTop]

Originally Posted by Joseph Hanna

I'm willing to put my money in a 300 watt Crest Power Amp any day, all day, endlessly before I'd EVER entertain some of the cheap, light weight 1000 watt Digital Amps.

Hi Joseph,

Which is why, I'd assume, that my three-year old Mackie SRM450 active Monitors, with more conventional but heavier power amps: a Class G, Parametric Servo Feedback for low frequency, and Conventional Class AB for high frequency is probably more reliable under varying operating conditions than the new Class D power-amp-Based Mackie SRM450V2. The older SRM450 is 10 lbs. heavier than the newer SRM450V2. Also, the older SRM450 speakers have a conventional magnet in their low-frequency speaker but the new SRM450V2 low-frequency speakers are neodymium-magnet equipped. Maybe some of that extra weight is worth it for the greater reliability of the SRM450 power amps? What do you think? Thanks.

Regards,

SpruceTop

[Joseph Hanna]

Originally Posted by SpruceTop

Hi Joseph,

Which is why, I'd assume, that my three-year old Mackie SRM450 active Monitors, with more conventional but heavier power amps: a Class G, Parametric Servo Feedback for low frequency, and Conventional Class AB for high frequency is probably more reliable under varying operating conditions than the new Class D power-amp-Based Mackie SRM450V2. The older SRM450 is 10 lbs. heavier than the newer SRM450V2. Also, the older SRM450 speakers have a conventional magnet in their low-frequency speaker but the new SRM450V2 low-frequency speakers are neodymium-magnet equipped. Maybe some of that extra weight is worth it for the greater reliability of the SRM450 power amps? What do you think? Thanks.

Regards,

SpruceTop

In audio, particularly live audio, the old adage that "you can't have your cake and eat it to" is a mantra. Light plastic boxes loaded with digital power amps, digital crossovers and neodymium magnet speakers with cheap aluminum frames are unfortunately gonna sound like.......... light plastic boxes loaded with digital power amps, digital crossovers and neodymium magnet speakers with cheap aluminum frames.

I know many who are willing to concede to that because the ability to tote them around with relative ease outweighs the lack of sonic response in their world. I'm good with that as long as we don't start confusing what the specs mean in the real world.

I'm not sure about reliability comparisons. The Digital Amps may well be very reliable. I do know that the market demands the QSC's and The Mackie's and the JBL's be light and powerful. That's what research says you and I want. That said ya just simply can not have light and powerful and concert level cleanliness and tone in one package. Somethings gotta give.

You're NOT gonna see Pink Floyd tour with Digital Power Amps and neodymium loaded turbo packs and for good reason

[geokie8]

What he said.

geokie8

[geokie8]

Originally Posted by Joseph Hanna

You're NOT gonna see Pink Floyd tour with Digital Power Amps and neodymium loaded turbo packs and for good reason

You will see them with a line array -- but it really shouldn't be compared to a SoloAmp (or BagAmp for that matter).

geokie8

[GordonHLau]

Originally Posted by tdrake

For all of these reasons, I can really see the benefit of a Solo Amp, Bag Amp or Bose system, though the first two make more economical sense to my personal approach to gear and performance...but I can't really see why I'd need to buy a really expensive small/highly portable, 1000 watt powered speaker.

Your economical reason is invalid here. A QSC K8 is cheaper than either a Soloamp or Bag Amp. Even throwing in a speaker stand, the K8 is still cheaper than the Bag Amp and several hundreds of dollars cheaper than a Soloamp. Dealers won't discount the Bag Amp either (so they told me) so I can even get a K10 w/speaker stand for less than a Bag Amp.

I still need to compare the K10 to the Bag Amp myself. I compared the BA to the SA and the BA was way better sounding to my ears but I didn't feel it had enough output. If the SQ of the K10 is somewhere in between the SA and BA, I might go for the K10 because of the additional headroom and versatility it will provide me (can use it as a PA, monitor, etc.), plus its not that much heavier than the SA.

GL

[Herb Hunter]

The QSC amplifiers are, I think, analog designs. The letter designation in, Class D, does not stand for digital. I'm reasonably certain that the only true digital power amplifier is the MX-D1 made by Yamaha which costs around $5,000. (It delivers 500 watts per/ch with a distortion rating of 0.003% at 1kHz.)

Using the max SPL speaker specifications of the QSC K series and JBL EON to draw inferences is problematic. One would need to know whether limiters are being used and their characteristics and, and of course, how the max SPL is measured, etc. I have the impression that JBL is more conservative with their specifications than QSC.

[Herb Hunter]

Originally Posted by GordonHLau

Your economical reason is invalid here. A QSC K8 is cheaper than either a Soloamp or Bag Amp. Even throwing in a speaker stand, the K8 is still cheaper than the Bag Amp and several hundreds of dollars cheaper than a Soloamp. Dealers won't discount the Bag Amp either (so they told me) so I can even get a K10 w/speaker stand for less than a Bag Amp.

I still need to compare the K10 to the Bag Amp myself. I compared the BA to the SA and the BA was way better sounding to my ears but I didn't feel it had enough output. If the SQ of the K10 is somewhere in between the SA and BA, I might go for the K10 because of the additional headroom and versatility it will provide me (can use it as a PA, monitor, etc.), plus its not that much heavier than the SA.

GL

How are you determining the headroom of the BagAmp and the K10?