Driver Advice

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clonman123
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Joined: Tue Sep 25, 2018 2:00 am

Driver Advice

#1 Post by clonman123 » Wed Oct 31, 2018 2:52 pm

Hiya :)
So Im building 2x Tuba24's for a bicycle trailer based 12v sound system.
I'm looking at getting the Eminence Kappalite 10" drivers....but I'm still not sure which is the best option to get in terms of impedence.
These drivers come in 4ohm and 8ohm: http://www.eminence.com/pdf/KL3010LF_8.pdf
I'm looking to power two drivers in parallel with one of these amps: https://www.rockvilleaudio.com/db15/ https://www.rockvilleaudio.com/db14/

Which would be the best option in terms of performance, reliability, dependability etc?

Grant Bunter
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Re: Driver Advice

#2 Post by Grant Bunter » Wed Oct 31, 2018 3:34 pm

You don't need the db15, according to it's specs, the db14 will put out 63V @ 4ohms, more than enough to blow your drivers.

2 x 8ohm KL3010lf's in parallel will present a 4 ohm load to the amplifier.
Any amp running at 4 ohms will have a lower power draw than the same amp running at 2 ohms.
Since you want to run off battery, that's the most efficient, more dependable and reliable...
Last edited by Grant Bunter on Wed Oct 31, 2018 4:37 pm, edited 1 time in total.
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

ACUA
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Re: Driver Advice

#3 Post by ACUA » Wed Oct 31, 2018 3:52 pm

the 4 ohm paralleled set would get you a 3ohm load to the amp, the 8ohm paralleled set would get you 5ohms to the amp. if they are not blowing smoke the smaller of the two amps is going to be capable of 44volts and the bigger 54volts, not sure what the limits needs to be with those Kappalites. my guess is the smaller amp will suite you fine with two of the 4 ohm drivers. for more performance, reliability and dependability get the bigger amp and just don't over power the drivers!!!
Advanced concepts underground audio

ACUA
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Re: Driver Advice

#4 Post by ACUA » Wed Oct 31, 2018 3:55 pm

those amps do 1000w and 1500w respectively at the 1% thd not quite as much as they so boldly advertise. you have to read the description to see their trickery. I agree with Grant, get the bigger amp and the higher impedance drivers for best results!!!
Advanced concepts underground audio

CoronaOperator
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Re: Driver Advice

#5 Post by CoronaOperator » Wed Oct 31, 2018 4:07 pm

Those ratings are most likely at 14.4 volts. I would x 0.75 to get the ratings at 11.8 volts which is about what your battery would put out under load.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

Grant Bunter
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Re: Driver Advice

#6 Post by Grant Bunter » Wed Oct 31, 2018 4:36 pm

ACUA wrote:
Wed Oct 31, 2018 3:55 pm
those amps do 1000w and 1500w respectively at the 1% thd not quite as much as they so boldly advertise. you have to read the description to see their trickery. I agree with Grant, get the bigger amp and the higher impedance drivers for best results!!!
Your two posts contradict each other.

:confused: I suggested the smaller amp :confused:
CoronaOperator wrote:
Wed Oct 31, 2018 4:07 pm
Those ratings are most likely at 14.4 volts. I would x 0.75 to get the ratings at 11.8 volts which is about what your battery would put out under load.
Good catch CO 8)
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

ACUA
Posts: 353
Joined: Sun Sep 25, 2016 6:21 pm

Re: Driver Advice

#7 Post by ACUA » Wed Oct 31, 2018 5:21 pm

I did not see your post until after I had posted my first initial post. You did not account for impedance raise of the cabs,

I would personally run the smaller amp on the lower 4ohm drivers. To save moneys.

I thought Grant had suggested running the bigger amp off a higher impededance, if money is no object it’s the better way to go
Advanced concepts underground audio

Grant Bunter
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Re: Driver Advice

#8 Post by Grant Bunter » Thu Nov 01, 2018 4:16 am

ACUA wrote:
Wed Oct 31, 2018 5:21 pm
I did not see your post until after I had posted my first initial post. You did not account for impedance raise of the cabs,

I would personally run the smaller amp on the lower 4ohm drivers. To save moneys.

I thought Grant had suggested running the bigger amp off a higher impededance, if money is no object it’s the better way to go
I am Grant :)

You're right, I didn't account for the impedance raise of the enclosure itself, very much on purpose.

The impedance raise due to the enclosure is 2dB in acoustic impedance, not electrical impedance.
While both acoustic and electrical impedance are a function of frequency (ie "impedance is frequency dependant"), as far as I'm aware, raising acoustic impedance doesn't alter electrical impedance.
As far as the driver in one of these designs goes, when considering electrical impedance, an 8 ohm driver is an 8 ohm driver, for example.
Particularly when trying to pair an amplifier and a driver together, I believe it's best to treat the driver alone as the sole consideration...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: Driver Advice

#9 Post by Bill Fitzmaurice » Thu Nov 01, 2018 6:54 am

There is a rise in electrical impedance, caused by the high impedance of the horn air mass load. The only impedance measurements I take are electrical, as the acoustical impedance is of no concern. Still, I would not mess around trying to run as low an impedance possible trying to get another 3dB of sensitivity to allow using an undersized amp.

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