QuestionI need some help in checking the compatibility or alternately choosing a subwoofer for the Harman Kardon CA470 amplifier whose specs are as follows
Type : 4-Channel
Amplification : Class AB
RMS Power @ 4Ohms : 4 x 85W
RMS Power @ 2Ohms : 4 x 135W
The amplifier will be powering the cars rear speakers infinity Kappa 693.9i 3 way with the following specs
Power Handling, RMS - 110 Watts
Sensitivity - 96dB
Frequency Response - 35Hz - 30kHz
Impedance - 2 Ohms
Now I need to choose the subwoofer and am confused due to the single / dual voice coils as to what would be the appropriate subwoofer because of the impedances. I want to use one subwoofer and the specs for the subwoofer are as follows for the amp mentioned above
IDQ12V2.D4 - Image Dynamics 12" IDQ Dual 4 Ohm Subwoofer
Voice Coils: Dual 4 Ohm
RMS Power Handling: 350 Watts
or
would this subwoofer be more appropriate
IDQ12V2.D2 - Image Dynamics 12" IDQ Dual 2 Ohm Subwoofer
Voice Coils: Dual 2 Ohm
RMS Power Handling: 350 Watts
Any help in choosing the right amp for the above configuration would be highly appreciated.Am confused with the dual voice coils at 2 Ohms and 4 Ohms as to what the output will be in ralation to the output of the amplifier
Thanks a lot in advance
Michael
AnswerThe Kappa's should perform superbly, just be sure to set the amplifier level and crossover point properly since this will be about 25 watts above their recommended power.
Choosing from one of those two speakers (with no doubt) go with the D2 sub.
Wire the two voice coils (VC) in series for a FOUR Ohm load on the two, bridged-mono amplifier channels. HK allows a minimum of 2 ohms PER channel.. so when bridging the two channels for a sub.. that is all you get, so 2+2 (stereo channels) = FOUR Ohms minimum in bridge-mono. ok?
That is how we arrive at 270 watts in bridged mono.
Just so you know, you can wire a single D4 Sub at 2 Ohms (parallel) or 8 Ohms (series). You can wire the D2 at 1 or 4 Ohms.
Up to a certain point, (price associated) most amplifiers will increase the RMS power rating when you decrease the impedance load placed on them. Never place an impedance load on an amp which is lower than it is rated to run or it will melt.
Here is a fine link to show you how to wire the coils in various ways (as well as SERIES, which you will be using on that D2).
http://www.crutchfield.com/learn/learningcenter/car/subwoofers_wiring.html
Bookmark that link!!
You will get about 270 watts RMS across the D2 speaker this way. If the sub has a good enclosure this combo will pound.
The H/K amp appears to be quite capable, but you might want to look at something like a ZX.700 5 channel, remanufactured Kicker amp since you are still shopping.
They will run 210 watts RMS at 4 Ohms or 420 at 2 Ohms (mono) so the D4 might work better with the kicker.
I have seen the ZX700 on ebay for about 200.00 :O
Here is a new one for a little over 300.00:
http://cgi.ebay.com/NEW-KICKER-08ZX700-5-AMPLIFIER-ZX700-5-AMP-5-CHANNEL_W0QQite...
In short, what you have selected should work pretty well.
A lot of factors can be taken into account like expectations and budget but your vehicle charging system must be able to handle either one of these amps.
Notes:
Set the LowPass crossover for the sub at least 1/2 octave from the maximum lower range of the speaker.
Match (tune) the amplifier levels to the systems' weakest link and Good Luck.
If you have any more questions (and you certainly may at this point), please let me know, Michael.
JM
