GTS_t
Mar 17 2003, 08:41 PM
I've recently bought another car and need to fit the speakers rescued from my previous ride. They are Kef 160M midrange, Kef 110M midrange and KU25 tweeters. I previously ran them as passive 3-ways from an MRV1000 using Kef crossovers.The trouble then was they couldn't get very loud and didn't sound particularly good probably due in part to their inefficiency and less than optimal crossover points. This time I intend to use my Alpine DREA500 crossover to run them active but my available amps are only 4x30 and 4x40WRMS V12s which I don't think would drive the Kefs adequately. Maybe if I ran them bridged I would have 2x100 + 2x120WRMS and just run the kefs as 6" 2-ways for now then add the 41/2"s in the kick panels later when I get a new amp.Anyones opinions on my thoughts for this system or any alternative will be appreciated.
thanx.
shiny_car
Mar 18 2003, 01:48 AM
welcome to CAA!
i don't know the KEF splits, only the generally high KEF reputation.
are they renowned for being really, really inefficient as you suggest? what power are they rated to?
only that the 2 alpine MRV-1000 amps i used to own were spec'd to 160/165WRMS per channel at 12V into 4ohm as per the birthsheets. far more power than the rated 100WRMS per channel.
was that not enough power?
or is it possible you did not have the gains tuned properly to yield full power from the amp?
if you run it actively via the alpine xover, another option would be:
*use the F400 to power the tweets and midranges: 4x40WRMS
*use the F300 bridged to power the woofers: 2x100WRMS
that'll provide 180WRMS rated power per channel. and realworld power will be reasonably more, although the 4-channel alpine amps are typically only 20~30% underrated powerwise compared with the 2-channels (like my old ones 60~65% underrated).
is the MRV-1000 not available for the front stage too?
GTS_t
Mar 18 2003, 02:40 AM
shiny_car Thankyou for your reply. The MRV1000 is earmarked to run the sub. The Kef KAR160M is rated 12-100W, KAR110M 5-70W, KAR25U 12-150W. These amplifier recommendations seem quite low but I expect the heavy crossovers are largely responsible for their low efficiency. One reason I couldn't get them loud is that the Kef crossovers have a bulb-like component that presumably protects the tweeter.When I turned it up the bulb glowed too brightly. I was told this indicates D.C. voltage due to the onset of clipping. Drew Stibbard recommended I go active. He sold me the DREA500 and said I should notice a huge difference.
Do you think the alpine amps still sound good bridged?
Thanx
shiny_car
Mar 18 2003, 01:37 PM
QUOTE
Originally posted by GTS_t:
I expect the heavy crossovers are largely responsible for their low efficiency. One reason I couldn't get them loud is that the Kef crossovers have a bulb-like component that presumably protects the tweeter.When I turned it up the bulb glowed too brightly. I was told this indicates D.C. voltage due to the onset of clipping.
ah yes, tweeter protection.
it doesn't necessarily suggest clipping, merely overpowering, which could be clean power or clipped power. but sure, the setup exists to avoid delivering too much power to the speakers...which may suggest that's as loud as they go?
QUOTE
Drew Stibbard recommended I go active. He sold me the DREA500 and said I should notice a huge difference.
for sure, passive xovers consume a reasonable amount of power due to their inefficiencies. the active setup will avoid this, so hopefully deliver slightly more power to the speakers...without the speaker/tweeter protection.
definitely worth a try. dedicated channels to each speaker should improve dynamics and power to each in your situation.
QUOTE
Do you think the alpine amps still sound good bridged?
yes, they do. the series I V12s (that you have) are well-designed around a good internal power supply with plenty of headroom. as such, they won't run out of puff when bridged and continue to deliver a nice gutsy, clean, dynamic signal.
the DRE-A500 is an excellent xover; pity they're no longer available.
so if you initially install a 2-way setup, then try out your plan of running 2 bridged 4-channel amps. if you go 3-way, then consider my proposal of one bridged, the other in 4-channel mode.
good luck
T-Bro
Mar 18 2003, 04:13 PM
i used to have the KEF Uni-Q 160Q coincident speakers in my system, UNBELIEVABLY musical and realistic sounding speakers - but they are unfortunately inefficient and 'quiet', and i was using the KEF matched crossovers for them, giving each 50WRMS which is what they are rated to handle. the clipping bulbs in my crossovers glowed with the music also, which irritated me because i didnt believe i was overdriving them.
so i dont know if more power will help, maybe it will but i think their design is inherently inefficient
GTS_t
Mar 19 2003, 02:21 AM
T-Bro I'll see how efficient they are active. If they don't get loud enough I might get me some of those B.A.Pro 6.5s. I auditioned a pair at Incar and they blew me away.
T-Bro
Mar 19 2003, 12:52 PM
yeah, thats the same process i went through, loved the KEF's but was disappointed with their inefficiency, so went looking for beautiful components and found the boston pro 6.5's
i think KEF got out of car speakers for a reason, they were basically putting delicate home audio technology into an environment they didnt research too well, for example the 160Q's had to have the basket redesigned shortly after release because the stupidly bulky terminals were preventing them being mounted in many doors. this is weird, because KEF also make excellent outdoor speakers, and as a point of interest, you may also wish to consider using those if experimentation and being 'different' dont bother you. i recall hearing of an award winning SQ car in the USA that used the 8" Uni-Q outdoor speakers, so its worth a try if you like the coaxial design (i do).
one caveat, the KEF's can be a little more live and 'real' than the boston pro's (at least the Uni-Q models were), but the bostons are far more versatile in that they work with any music type if they are tuned correctly, imaging is slightly sharper, they DONT break (something the KEF's do) and they are more configurable with their split or axis-mount options.
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