Build some speakers using 4ohm 75w car speakers and a 4-8ohm amp??

[admin_exported]

This query may well have some audiophiles in a frenzy but I'm curious to whether I can make this work:

I have a pair of Kenwood 6x8 75watt RMS 4ohm car speakers and have removed them from my old car. I am also in the process of buying a budget amp and speakers for around 100-200GBP each (my pund sign doesnt work in this window for some reason). I was wondering if I could buy a Marantz PM4001 amp and make some fairly decent speaker boxes out of MDF and install my car speakers. The Marantz amp can switch to operate at 4ohms. Will I get a fairly decent sound out of them without damaging any equipment? Im not an audiophile myself so my ears probably arent as fine tuned as others.

Thanks

N

 

[Andrew Everard]

Well, they'd work, and the amp would probably have no problems driving them, although I'd suggest you go a bit easy on the volume level: car audio amps tend to have better protection against clipping if you push them too hard, and it might be possible to damage a hi-fi amp if you crank the levels too high. The rule of thumb is 'first sign of distortion, back off on the level.

But there are a few qualifiers to the above statement. First, you've got to build some fairly decent speaker boxes, as you put it, and this will involve calculating the correct volume and dimensions to get an even balance from the speakers. It looks like the kenwoods you have are something like the custom-fit KFC-6880s, which are a slightly shrunken version of the more usual 6x9s, in this case designed for the likes of the Mondeo, Focus and some Mazdas, so finding out much about them to put into the usual cabinet design programs is going to be tricky.
There are some specs here - at least if we're talking about the same speakers - but they're not much help in terms of the usual parameters required by cabinet design programs such as WinISD, which is available in beta form for you to download and try. But such software might give you some idea of enclosure sizes and porting, and would certainly be better than just slapping together a box and hoping.
To give you some idea of enclosures that work with speakers of this kind of size and design, have a look at this site - as you'll see, the enclosures aren't exactly small!
If all this is sounding like quite a lot of work for unpredictable results, I'd have to agree - especially when there are very competitive small-box speakers available for £100 or less, which will give much more predictable performance. I'm thinking Tangent Evo, Q Acoustics 1010 or Cambridge S30 here.
I'm not in any way trying to dissuade you from some experimentation - after all, it's how most people in the audio industry started out - just trying to avoid you doing a lot of work and being disappointed.
Hope all that helps