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In the boot of her Roadster, forward of the fuel filler area, theres a wasted space that looks like it could take a smallish two channel amplifier. Anyone fitted one in there?
Ive not had the cover plate bit off yet to look properly, but Im hoping one, or perhaps two smaller, bridged amps might go in there,

She isnt after huge amounts of power, just a bit of poke for when the roof is down along with her foot and after sorting speakers, dampening the doors etc, she/I am on a roll.

Any thoughts on that little boot corner space?
 

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Not answering your question I know,but if you fit an Alpine radio they do a plug and play amp that boosts it to 4x100w,and just plugs straight onto the radio loom,then fits behind the dash with no fixing or extra wiring. I have it in my mk2 and it's in the gap between radio and glove box. Brilliant solution and sounds great with none of the hassle.
Alpine KTP-445 is the model if I remember rightly,and is around £100
 

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Not answering your question I know,but if you fit an Alpine radio they do a plug and play amp that boosts it to 4x100w,and just plugs straight onto the radio loom,then fits behind the dash with no fixing or extra wiring. I have it in my mk2 and it's in the gap between radio and glove box. Brilliant solution and sounds great with none of the hassle.
Alpine KTP-445 is the model if I remember rightly,and is around £100
I have voltage drop concerns. If it's a 100w high efficiency design it will need just short of 10 amps rms. I have seen the wiring and the fuses in a mk1, It won't give it's best.

They claim it's 180w rms. That would just blow the fuse in most cars. It's probably some phillips tda chips really.

Them chips are quite good at lower power levels like this. It is a pitty that manufacturers generally stick them in big boxs to add value, as it's a tiny design that could be used if the packaging was right. Like alpine probably have here, and ford did with there scorpio amps.

I do like this alpine offering, but I feel it's priced high as it saves fitting costs. The fact it won't meet it's spec makes me want to ring the law, but it's to be expected. There just keeping up with the jones's. It's about 3db up on the headunit. A noticeable margin.

If I had one I would check it's permanent 14.2v l was present, and what it drops to when you turn it up. I reckon it wants a wire from the battery.

I have a small amp (240w) to go in that space, but it will sit at 45 degree's. Who's going to see though, if you have boot carpet. Not as nice as it fixing to a flat surface but it can be bracketed in with some mechano or something.
iirc the gap is about 6.5" and amps start at around 8"
 

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I guess it depends what you want from your amp. There wasn't enough power to punch my speakers I put in due to the head unit not having enough balls,with the amp it's transformed it,with only 2/3 volume level they're performing as they should.
Could you not put an amp in the big empty space under the rear shelf? I was amazed how much space is in there when I fitted my rear speakers,with a lot of scope for sound deadening whilst In there too if fitting rears
 

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Discussion Starter · #6 ·
Thanks for the replies. Ill have to get that cover off in the boot and have a measure up over the weekend.

That little Alpine KTP-445... its got bold claims, and Im sure it does boost the output a little, but Id feel ripped off if not getting its full potential due to a lack of power getting to it, never mind blowing the odd fuse.
Wouldnt taking the power from the cig lighter socket be an idea? Surely that runs at a fair few amps more than the stereo circuit? I only use the socket for sat navs/phone chargers, so I cant see it getting overloaded.

Either way, ill report back with my boot findings.
 

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It's plug and play and goes in the loom midpoint. Packs a hefty punch in comparison to the head unit without it. Runs very loud most of the time in my car,never gets hot,never blown a fuse. It's only 4x50w,the same as the head unit,but adds onto the 4x50 of that to give the 4x100. No idea where you're based,but if youre ever near me you're welcome to see it working if you have second thoughts.
 

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There's a good review of the Alpine KTP-445 on Talk Audio <clicky>. The review is very positive and worth reading.

The amp is rated at 4x100 max, 4x45 RMS and is class D (making it more efficient than the usual class C amps). What you should bear in mind is that it has a 15amp in-line fuse and that the power wire for it isn't capable of handling any more than that. A bit of simple physics tells you that 12V at 15amps gives 180watts (which, if you divide it by 4, gives 45watts), so even if you assume 100% efficiency you're not going to get more than 4x45W.

The head units speaker output (comically claimed by most manufacturers to be 4x50W but more likely to be 4x25~30RMS) is now just acting as an input signal to the Alpine amp. The speaker will only ever see the output of the Alpine amp because that's what it's wired to, so you can't just say that bolting a 4x50 amp onto a 4x50 headunit now gives you 4x100 because it's simply not true (and can't possibly hold true because the cars wiring loom is protected by a 15amp fuse).
 

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Discussion Starter · #9 ·
Thanks for the review link, Roadster 2.5. I thought this thread was going to dive after the 50w + 50w thing, no offense to anyone, but theres a lot of bunkum around re stereos and numbers.

Ive been looking at the newer KTP-445U as its definitely bridgeable, will take pre-out or high level outputs and also has hi-pass filters which would help lose low end rattle and give more power to the frequencies the door speakers are happier to play.
The S/N ratio is a bit worrying, we are used to Genesis amplifiers and Dynaudio speakers, but with higher volume only really needed with the roof down hopefully this wouldnt be an issue should she buy the wee amp.

I read that the 15amp stereo live feed is the same feed as the cig lighter, so my thoughts on taking power from there are pointless if the info is correct?

Anyway, she has been for a blast in the car today with roof up and down. Reports are that with the roof up, the music is brilliant now with new speakers etc, but with the roof down not so clever... looks like that little amp is on the cards. Im fairly pleased as the Rainbow speakers I fitted love a bit of poke, as does the missus.
Id rather stuff something in that little hole in her boot and get some higher quality sounds though.
 

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I stand corrected if I've not got my stats right.wasnt aware there wa an older model actually. Mine is the 445u. Part of me thinks figures etc are not that relevant anyway,if it sounds good then happy days.
I have Pioneer 8" 3ways in my door,Sony tweeters up top,and 6"pioneers in rear deck.loads and loads of Dynamat,with Alpinew213 and KTP445u. It's bloody loud with roof down at 80.1000 miles round Europe in the summer and it excelled at all times. Same set up was poor before the amp.It drives the fronts superbly,with some in reserve,and I have been asked more than once where the sub is (I don't have one)
Anyone who thinks I'm exaggerating my results,please come and listen!
 

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Discussion Starter · #11 ·
if it sounds good then happy days.


Might be worth bridging it to the front speakers and running the rears off the head unit if youre anything like me and like music coming from in front of you and just a bit of "rear fill".

Thats what we are looking at doing anyway, not got rear speakers, just the headrest ones which are set really low and not noticed until theyre faded right off and then theres something missing from the sound, so theyd be run from the head unit still.

I know what you mean re "wheres the sub?" I get the same in my crx (when the sub is out) just from 6.5" Dynaudios and well damped doors. Although theyre seeing well over 120 real watts each.


Its up to her to buy one now, Ive spent enough on the car and need to tend to mine. Ill pop back and post how we found with it as its a simple and ideal solution for an MX5.
 

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Discussion Starter · #13 ·
In that case Id definitely take the time to bridge the amp to the front speakers, run the rears direct from the stereo and find a spot on the fader that matches the sound as it is now - itd boost the front speakers a lot, especially at the low end.

But as long as youre happy, thats all that matters.
 

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With a fabric hood and a loud system I don't need it any louder with the music I listen to! Lol
I was aware of this sat at some lights for a couple of minutes at a junction just yesterday and turned it down as I was aware of what I was listening to and I got more than one look.
(I'm not an attention seeker or chavvy boy racer!)
 

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Volvo use an alpine Class D (130w X five) with dynaudio's.
 

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Discussion Starter · #17 ·
Where they should have used Genesis and steered clear of class D for decent quality mids and highs. Their system sounds good, yes, but it could be better.

All in my personal preference and opinion, of course.
 

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Genesis are designer gear. Hand made in fancy boxs. I doubt they could meet demand.

The very best factory supplied audio system is the B&O one that uses class D amplification.

Oddly both alpine and B&O are using the phrase ICEpower amplifier and saying it is there own. Last I looked alpine were pioneer.

I find it odd that class D amps are the croutons bobbing on top of this car audio soup. Thing is though, it is a vehicle. Thats why signal to noise is quite unimportant. Your only going to get the charicter of the music. It will never be a live concert with the restraints a vehicle offers.

I scrapped my class A amp project because of this. Most never even started such a project because of the excess heat and power consumption which goes in hand with size and weight. My 50+50 was going to fill half a cubic foot and give 400W of heat off. I thought of an a-b compromise but that turned towards modding a basic blaupunkt, then the fact you can pull an amp from an old volvo thats second best in the world. A 50+50 class D might only give off 10w of heat and fit in a typical small amplifier box. That kind of efficiency can play very loud for decent periods of time without the engine running. My 50+50 class A would of lasted a toasty 45mins.

I should really get my audio project off the ground again. I have morels to go in. There a dyn woofer made under licencee, using morels own tweeter in a coaxial design. A compromise that will give me the right charicter, but might aswell be class D driven. It is good enough for them. I just hope Im not left searching for a british amp afterwards. We are being very demanding though, thinking that wont be good enough.
 

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Genesis are designer gear. Hand made in fancy boxs. I doubt they could meet demand.

The very best factory supplied audio system is the B&O one that uses class D amplification.
To say that Genesis is designer gear in fancy boxes (which I don't disagree with in isolation) and then follow up with B&O being the vey best is a joke right?
 

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The veyron uses B&O and thats about £1,000,000

Oh I had a whole post worked out before I saw that signature. Now I can't complete a sentance without looking again.

Something about subjective and factory supplied.
 
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