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Driver Advice

Posted: Wed Oct 31, 2018 2:52 pm
by clonman123
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?

Re: Driver Advice

Posted: Wed Oct 31, 2018 3:34 pm
by Grant Bunter
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...

Re: Driver Advice

Posted: Wed Oct 31, 2018 3:52 pm
by ACUA
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!!!

Re: Driver Advice

Posted: Wed Oct 31, 2018 3:55 pm
by ACUA
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!!!

Re: Driver Advice

Posted: Wed Oct 31, 2018 4:07 pm
by CoronaOperator
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.

Re: Driver Advice

Posted: Wed Oct 31, 2018 4:36 pm
by Grant Bunter
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)

Re: Driver Advice

Posted: Wed Oct 31, 2018 5:21 pm
by ACUA
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

Re: Driver Advice

Posted: Thu Nov 01, 2018 4:16 am
by Grant Bunter
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...

Re: Driver Advice

Posted: Thu Nov 01, 2018 6:54 am
by Bill Fitzmaurice
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.