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Dan's Mazda Miata meets the Alpine KTP-445A Power Pack

A compact amp for any car

Dan and his Miatas

Dan, a Crutchfield web designer, managed to perform a major sound upgrade in his 1991 Mazda Miata (the silver one in front there).

Increasing power by adding an amplifier always improves the sound quality of a car’s stereo system. It allows your music to play loudly and clearly over wind and road noise — which is especially beneficial in a convertible. But many people worry that they don’t have enough room inside their car to install an amplifier. Putting in a small, compact amp solves this problem handily, as we demonstrate in a tiny Mazda Miata sports car.

A Crutchfield web designer's Miatas

When he’s not designing web pages for Crutchfield, Dan likes to race his Miata. He actually owns two of them and although he’s not a professional driver, he enjoys pushing his racer to the limit around a couple of open-to-the-public race courses in the state. While he wouldn’t think of wasting resources by putting a new stereo in his racing car, he wanted some higher-quality sound for his everyday ride, a 1991 Miata. He already had an Alpine receiver he wanted to install in the dash.

When we heard what he was planning, we knew it’d sound even better if we added an Alpine KTP-445A compact amplifier to his system. Dan was excited about the prospect.

Connecting the power pack's wiring

The Alpine power pack fit right under the passenger seat. We used existing slits in the carpet to get the wiring to the amp.

An amp that plugs in and plays

Alpine designed the KTP-445A Power Pack to simply plug into one of their receivers for power and input, and into the vehicle’s stereo harness for its output. On top of that, it's tiny — just over 8 inches long, 3 inches wide, and only an inch and a half tall — yet still puts out 45 watts RMS, which is plenty for a small car like the Miata.

Finding a mounting location

In a typical passenger car, the Power Pack often fits in tight spots, such as behind the dash or in the glovebox. The Miata, however, proved a little more challenging, due to its severely limited space. Luckily, we found just enough space under the passenger seat.

The amp’s harnesses were long enough to run the connections from behind the receiver in the dash, under the carpet, and on to the mounting location. No other wiring was necessary. We only had to remove four bolts, and the seat came right out, giving us plenty of room to work. We used self-adhesive strips of velcro to keep the amp from sliding.

Feeding power to a new set of speakers

A new stereo and amp weren't going to do Dan much good if he didn't replace his factory speakers. After 23 years of duty, there really wasn't much left of them. It's a wonder they still played at all. Not surprisingly, the Miata presented a few spatial challenges here, too. This limited the models we could choose from since Dan didn't want to modify his car too much. 

Factory and Polk speakers

Dan's factory speakers were completely falling apart. It's an understatement to say that the new Polk dbs made a huge difference.

We ended up replacing the factory disasters with a set of shallow-mount Polk Audio db speakers, which dropped right in, and didn't interfere with his windows rolling down. Dan had to remove the factory speaker grilles to accommodate the new speakers (which is not unusual with a Miata), but that simply lets him show off the distinctive copper Polk woofer cones. Luckily, the dbs come with grilles, so they're protected from the dangers of stray feet.


The Alpine CDE-HD149BT in the Miata's dash

The Alpine CDE-HD149BT receiver looks fantastic in Dan's dash

How he likes it now

Dan loves the sound now. He reports that “there’s finally a bottom end and the highs are much crisper. I can also turn the volume way up without losing sound quality. Now cruising with the top down, I can actually hear the music.”  And it doesn't hurt that the final result looks fantastic, too.

Your turn

Do you have a compact car with a sound system you'd like to upgrade? Just need more power? Check out our line of compact amps. And give us a call at 1-888-955-6000 if you'd like some advice on the finding the best gear for your ride.

Dan in the Miata
  • Buck Pomerantz from Crutchfield

    Posted on 9/9/2016

    Aaron, The Alpine KTP-445A's harness plugs into an Alpine receiver and gets its power and ground connections from there.

  • Aaron

    Posted on 9/9/2016

    This placement is great unless you have leather seats - they are just slightly lower and the amp is just tall enough to get in the way. If you rarely move the seat, you'll be fine :-)

  • Aaron

    Posted on 9/8/2016

    ('97 Miata STO with Apline CDE-124) I'm about to install the KTP-445A as Dan has done. The harnesses are all quite useful and easy, but to where did he connect the power and ground?

  • Buck Pomerantz from Crutchfield

    Posted on 10/12/2015

    Derek, As far as we can tell, no amplifier was included in the Miata Special Edition. This means the amp you're seeing in your trunk is an aftermarket amp added by a previous owner.

  • Derek from Houston

    Posted on 10/7/2015

    John, I have a 91 Miata BRG Special Edition, just got it and sorting out the audio so thanks for this article. Do you or Dan know what the amp in the trunk is? It is direct wired into the factory wiring harness, might have been part of a stereo upgrade option?

  • Buck Pomerantz from Crutchfield

    Posted on 7/17/2015

    Martin, Dan installed an Alpine CDE-HD149BT receiver, a pair of Polk Audio db651s shallow-mount speakers, and an Alpine KTP-445A compact 4-channel amplifier in his '91 Miata. The fitment for your 1990 model may be different. You can use our vehicle selector to find out what gear fits your car and get some info on what else is needed for the installation. Or, you can give one of our Sales Advisors a call at the toll-free number listed at the top of this page.

  • Martin Haynes from Sierra Vista, AZ

    Posted on 7/17/2015

    I like Dan's set up in his Mazda. I would appreciate knowing what model of Alpine Radio or Alpine Radio's this would work with this set up including the type and model of speakers and also the model of the amp used. I have a 90 Mazda Miata with removable hard top. Thank you, Marty Haynes

  • Buck Pomerantz from Crutchfield

    Posted on 6/29/2015

    Sean, The headrest speakers in the Miata act like tweeters - 3-1/2" speakers crossed over at 2500 Hz. Crutchfield's research notes point out that the headrest speakers in the '91-92 Miatas are extremely difficult to get to, that you would need to fabricate a custom mounting bracket, and hard wire the new speaker to the factory wiring. This is why Dan and a lot of people just disconnect the headrest speakers and enjoy the stereo sound coming from front speakers alone.

  • Sean from Weirton wv

    Posted on 6/26/2015

    How about speakers for the headrests. Cant seem to find that item. Any ideas. Thanks. For a friends car that i already pit in radio and frt spks. Rear spks dry rotted and sound really bad now.

  • Buck Pomerantz from Crutchfield

    Posted on 6/25/2015

    John, I am so sorry I didn't describe the headrest speakers and what Dan did with his. The headrest speakers in the Miata are really just tweeters - 3-1/2" speakers filtered to only play 2500 Hz and up. If I recall, three of the four were blown, Dan didn't want the soundstage broken up the way they made it sound, so he disconnected them.

  • John from United States

    Posted on 6/24/2015

    Hi, great article, but you made no mention of the seat headrest speakers...did Dan upgrade them?


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