People,

I am in the process of purchasing some 8" mid bass drivers (175WRMS) for my front stage. They will be running with some Kicker Resolution 5" splits (90 WRMS).

My question is I have 2 amps to run the front stage. Them being a Kicker KX300.4 (150WRMS 2CH 4OHM 0.04%THD on board filter to 200Hz) and a Pioneer GMX-944 (250WRMS 2CH 4OHM 0.008%THD on board filter to 120Hz)?

The reason that I mentioned the filters, is that I am going to LPF the 8's with the on board filter and don't know whether I would notice the difference between 120Hz and 200Hz.

Is the THD critical?? Is 0.04% bad for SQ?

Damo

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SILVIA WA
www.silviawa.com

AUDIO COMPONENTS
Pioneer DEH-P7350
Kicker Resolution 6" Mid Driver
Kicker Resolution 1" Titanium Tweeter
Kicker Solobaric 12" Subwoofer S12L7D2
Kicker KX300.4 (fronts)
2xKicker KX400.1 (sub)

You will certainly notice the diff in those filter points, there is a lot of activity in 120~200Hz range. 200Hz would be preferable to get value from the 8s combo IMO.

A THD of 0.04% is FINE for SQ, you will NOT hear any differences with those 2 numbers. The bigger SQ differences will be found in the amplifiers' overall topology/output stages/power supplies.



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Mazda SP20 - NOT yellow,Dynamat Extreme and G Spot in front doors
HU - Alpine CDA-7876RB
Audison VRx 2.150EX front stage amp
JL Audio 500/1 Class D monoblock sub amp
Front Stage - Morel HCW 6.5 woofers, Morel MT2 tweeters, Morel MX2.2 x-overs.
Rear fill - stockies with power from HU (not that they get any)
Sub - Kicker S12L72 in 75 litre 30Hz slot-ported display box.
Stinger cables and connectors etc
TEAM AUDISON SQ WITH ATTITUDE

i'd be giving more power to the 8's. THD is irrelevant, the specs are basically just dreamed up by manufacturers and dont apply in the real world,
i thought the .4 on the end of the kicker model meant that it was 4 channel?

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'96 Mirage, currently resembling a tin can
uninstalled: Rockford RFX9300, Focal 165W3's Vrx 2.150 & 1.500
Power by: HERTZ audison OPTIMA StingerAerpro
TEAM AUDISON

don't worry about THD, that figure is low, it takes quite abit of THD before you start messing up your system. i've done listening demo's in my SQ car and several percent THD is hard to pick up. get to 10% THD though and its pretty easy to notice. so a fraction of a percent is nothing to worry about, certainly do NOT buy amps based on being slightly lower in THD alone as its just not relevent to the human ear.

as for crossover points, i side with critter, midbass easily reaches up to 200hz, even up futher, so the 200hz LP would be the way to go given your setup. if you choose 120hz LP your midbasses will basically be little subs and not fill in the part of the spectrum they are supposed to.

just remember to make sure that the x-over points for the misbass make sense in relation to your midrange/tweeter combo a few quick calculations on some notepaper, and some auditioning tests, will do the trick

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Custom SQ System

Source: Clarion DRX-9675z - Front Stage: Boston Acoustics Pro 6.5's - Centre Channel: Boston Acoustics FS50 Midrange - Ambient Satellites: Boston Acoustics 3/4" Kortec Tweeters - Processors: Audiocontrol EQT's - Subwoofers: Earthquake BR12's - Amplifiers: Kicker IX404's - Power: Stinger 1 Farad HPM Capacitor
Sounding sweet and taking it to the street

quote:

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Originally posted by Mr_Bob:

i thought the .4 on the end of the kicker model meant that it was 4 channel?

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You are correct, but this is the way Kicker works.

Their .2 series (2ch) the WRMS is determined at 2 OHMS. Therefore to get 150WRMS per channel at 4 ohms you need a KX600.2 which is not being brought into Aus, and very expensive (relative to power).

Alternatively you buy the .4 series which is rated @ 2 OHMS. A 300.4 will produce 75x4 at 2 OHMS, 38x4 at 4 OHMS, or 150x2 at 4 OHMS. Alot cheaper and readily available.

Damo



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SILVIA WA
www.silviawa.com

AUDIO COMPONENTS
Pioneer DEH-P7350
Kicker Resolution 6" Mid Driver
Kicker Resolution 1" Titanium Tweeter
Kicker Solobaric 12" Subwoofer S12L7D2
Kicker KX300.4 (fronts)
2xKicker KX400.1 (sub)

quote:

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Originally posted by T-Bro:


as for crossover points, i side with critter, midbass easily reaches up to 200hz, even up futher, so the 200hz LP would be the way to go given your setup. if you choose 120hz LP your midbasses will basically be little subs and not fill in the part of the spectrum they are supposed to.

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I side with critter aswell, but I am still curious if the 5's will run down to 120Hz to cover the 120Hz and above range, so that I can get more power to the 8's.

The reason I ask is that I have also read that for speakers producing above 100Hz, for best staging, should be mounted on axis. I do not have space in the doors to mount the 8's on axis. Am I correct, or completely lost in the world of SQ?



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SILVIA WA
www.silviawa.com

AUDIO COMPONENTS
Pioneer DEH-P7350
Kicker Resolution 6" Mid Driver
Kicker Resolution 1" Titanium Tweeter
Kicker Solobaric 12" Subwoofer S12L7D2
Kicker KX300.4 (fronts)
2xKicker KX400.1 (sub)

I have a Kicker 2 way Active crossover sitting here on my desk (current use = paper-wieght), this could solve alot of your problems. fully configurable, 1 high pass and 1 low pass filter

high pass 40 - 300hz
low pass 40 - 300hz
both with 18db octave

$50 and its yours, im in Perth (Canning Vale)
let me know if your interested

Cheers
Beau Alderson
Prez - HyperWA
www.HyperWA.com

i figured that was the case witht eh kicker amp, either that or (shudder) you had allocated the other 2 channels for rear fill.

Hyper has the solution.
i'd use an external Xover, and use the bigger rated amp for the mids and the weaker one for the splits.

------------------
'96 Mirage, currently resembling a tin can
uninstalled: Rockford RFX9300, Focal 165W3's Vrx 2.150 & 1.500
Power by: HERTZ audison OPTIMA StingerAerpro
TEAM AUDISON

yes, i was going to suggest buying an outboard active xover too. will provide much better flexibility and tuning to help get it right.

of course you'll also need extra RCAs and a power supply to the xover, and mount it somewhere.

BP the 8's using the HP in one amp set to say 70~80Hz, and LPing them via the outboard xover at 300Hz. you could even consider buying a xover that allows a higher LP filter, maybe up to 500Hz.

then HP the splits at a corresponding point to match or maybe overlap slightly the 8" speakers.

maybe compare both amps in each role to find which combo is best: kicker for midbass, pioneer for splits or vice versa.

good luck

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