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Discussion Starter · #21 ·
Amplifiers

So far, I've covered the driver choices, sound deadening, and the MiniDSP. In this post, I'm going to cover the amplifiers I chose for this job.

Front Stage Amplifiers
For the front stage, I'll be using two separate two-channel amps. These amps are a Coustic Power Logic AMP-160 and AMP-460. The AMP-160 will be used to power the tweeters, and the AMP-460 will be used to power the woofers. These provide 35Wx2 and 100Wx2 respectively @ 4ohms. These amplifiers were built in 1992, work perfectly, and cost me $80 shipped for the pair. I chose these because they meet my needs perfectly for power requirements, and because they are reliable. The fact that they've been running for ~20 years is proof of that reliability. They provide clean power and sound great.




Now, before I continue, I need to clarify some information regarding impedance. Some of you may have noticed that the speakers I chose are 8ohm speakers. This is merely a nominal impedance, which is defined as an approximate impedance across the entire frequency range. Speakers generally have specific impedance curves, through which they present the amplifier with a different load depending on the frequency. Here's a sample of an impedance curve. Note the different impedance measured at different frequencies:



Impedance typically spikes near the resonant frequency of that driver. In my case, the MDT-44 tweeter's impedance is actually ~6ohms from 1300hz on up to 5000hz, hits 7.5ohms at 10,000hz, and 9.5ohms at 20,000hz. One thing to note is that in general, higher frequencies will not need a whole lot of power to get loud. You will notice that people may put 500-1000W through subwoofers when they want to get more volume, yet their tweeters aren't rated for more than 20W RMS. The MDT-44 tweeter I'm using will play 91db at 1W/1M, and tweeters typically don't experience high dynamic peaks like a subwoofer would.

Since I'm using a ~6ohm load on an amplifier that can produce 35W x 2, I can realistically expect a 20% reduction in available power over what it could produce at 4ohms, which gives me ~28W RMS per channel. Across both speakers, I've calculated ~115db SPL at 1 meter (shoved in a corner with boundary loading) with both of these speakers if I reach the amplifier's maximum output, which in all honesty will be louder than I will ever care to listen if I value my hearing.

The AMP-460 will be able to deliver ~75W RMS per channel to the Dayton DA-175, which will also be plenty of power.

This is actually a benefit to me. A higher impedance allows the amplifier to run more efficiently, thus drawing less power and creating less heat. For a given wattage level, an amplifier will run cooler at 8 or 6 ohms than it would at 4 ohms because less energy is being wasted as heat. Higher efficiency also means there will be less stress and load on my electrical system.


Subwoofer Amplifier
To power the IDQ15, I'll be using an Alpine MRP-M1000. I've been using this amp for a while, but I purchased it for $150 last year. Run at a 4 ohm load, I'll have 600W RMS of power available. At this impedance load, this amplifier is 80% efficient, which makes it a great choice for my needs. Since the subwoofer is rated for 400W RMS, I'll have a bit of extra power for heavy dynamic peaks and will ensure that I can provide the subwoofer with distortion-free clean power up to its mechanical excursion limits without sending a clipped signal.

 

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Sit in my 95 Regal and I can guarantee you that you wouldn't ever know that there aren't any back speakers. The truth is that cars have so many reflective surfaces that the sound is always everywhere. If it's designed correctly, it will sound just as rich, full, and immersive.

Describing sound stage is very difficult until you hear it for yourself. In a well designed sound stage, you'll never pinpoint where the sound is coming from because of those reflections, so don't get the impression that you'd be able to identify two separate point sources; that's not what we're doing here.

If you want to pinpoint instruments, you'll need a flat frequency response and good phase and time alignment. I'll describe this briefly. Say you are sitting in front of a home theater speaker, something that looks like my recent design:



Now, say you're 3 feet away from the speaker and everything is at ear level. The woofer and tweeter are equidistant from your ears. Now, put the speaker on the ground and stand 3 feet away from it. What happened? The woofer is now farther away than the tweeter. The critical issue with this is in crossover overlap. In order to prevent a woofer from sounding distorted by playing too high of a frequency, you need to roll off frequencies above that point. In order to protect a tweeter from playing bass frequencies, you need roll off frequencies below a certain point. Here's the crossover sim for the above speakers. Click to enlarge:



The thick black line is the total frequency response. It's pretty **** flat in the usable range. the thick blue line is the woofer's frequency response after the crossover has been applied, and the thick red line is the tweeter's frequency response after the crossover has been applied. Those two overlap from 1000hz to 6000hz in order to "sum" and create the continuous black line. They are time and phase aligned for the sound to reach your ears at the exact same time when you're sitting directly in front of them, aka on-axis. Now, if you are off-axis and the woofer is farther from your ears than the tweeter is, what happens? The sounds from both tweeter and woofer in the "summed" range reach your ears at different times. The result is a sound that is not as clear, crisp, or detailed as one would like.

Now, take this concept and multiply it by 10 and that's the problem you have in car audio. You cannot possibly time and phase align both your front and your back speakers in order to have the same clarity you would in a home theater with two speakers at ear level. Furthermore, the reflections of the back speakers create destructive interferences that actually over-boost some frequencies and cancel out others, creating peaks and dips in the frequency response. The more speakers you have, the worse this problem becomes.

In the end, you're best off using two front speakers. The car's cabin will reflect sound from enough surfaces to create enough ambient noise in the back of the car to make up for what you think you've lost. The result will be the clarity you're looking for.

As for the bass you're looking for, I could spend a LOT of time going over this, but I've written up an explanation before so I'll just forward you to it instead. A lot goes into sub box design that most people have absolutely no clue about. To get that transparent bass you're talking about that just feels right, you need both a well designed sub and a well designed box.
Why sub boxes are important

Sit in my 95 Regal and you won't be able to tell that the sub is in the trunk. It will just be everywhere and it will be tonally precise, accurate, and musical. Now that's a word you have to hear to understand. Hearing a truly musical sub like the Image Dynamics IDQ15 I've chosen for this project will give you one **** of an "aha" moment followed by a "holy sh!t" moment, followed by speechlessness.
I don't know what most of what you say means but I get what you're saying. Thanks for posting links of the products you recommend, definitely be saving and might take you up on the box design when I jump into sound.

Maybe you can post a dumbed up explanation for those of us (ie. me) that don't don't understand all this stereo phonics talk. lol

"Buy this, this and this. Put it together like this. Because Boom!"
 

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love your thread, very informative. I have the upgraded pioner system and it just isnt doing it for me so ive decided to duplicate your setup. The questions that i have so far are what to do with the center channel speaker in the dash and can i use the wire harness going to the factory amp for the aftermarket stuff. id really rather not have to run all new wires to the speakers.
 

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Discussion Starter · #24 ·
I don't know what most of what you say means but I get what you're saying. Thanks for posting links of the products you recommend, definitely be saving and might take you up on the box design when I jump into sound.

Maybe you can post a dumbed up explanation for those of us (ie. me) that don't don't understand all this stereo phonics talk. lol

"Buy this, this and this. Put it together like this. Because Boom!"
Well, for the most part, I can do that, but I'd also like to teach you how things work and why. The MiniDSP really does take car audio to an entirely new level if you know how to do use it, and throughout this project, I'm going to try to explain how to use it to the best of my ability.

Please feel free to ask questions here. Chances are, you're not the only person who has them. It doesn't matter if you think they're elementary, I'll explain them so you can better understand what's going on here.

I'll design you a box for free, just ask. I'd prefer to teach you how to build one, but I also build boxes if you don't have or can't get access to a jigsaw, dremel, or router and some clamps.

love your thread, very informative. I have the upgraded pioner system and it just isnt doing it for me so ive decided to duplicate your setup. The questions that i have so far are what to do with the center channel speaker in the dash and can i use the wire harness going to the factory amp for the aftermarket stuff. id really rather not have to run all new wires to the speakers.
Thanks! I'm glad this is informative. I'm not 100% sure if the PAC harness will work with the Pioneer system, but you could always use a different line out converter if it came down to it. It wouldn't be too difficult to do so.

If you upgrade, the center channel goes bye bye. You could try to keep it and see how it blends with the rest of the speakers, but being a car audio system and not a home theater, I think you'd be better off without it.

I'm fairly certain you can re-use the wiring that already goes to the speakers. Running wiring is the biggest pain in the butt for car audio, so that will save you some time. You'll just need to know which wire is which and you'll have to cut wires and possibly extend them with butt crimp connectors to get them to your aftermarket amp. Personally, I'd just run new 18 gauge wiring, but I've always installed everything from scratch.
 

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im sure the stock center speaker wouldnt blend well at all but that maybe one matched to the new setup would help the sound stage since its closer to ear level. what do you think?

ive searched and havent found to much detail on the upgraded pioner system. With having a nice sub in the trunk should I compleatly remove the 6x9 subs froom the rear deck to help the sound enter the cabin area?
 

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Discussion Starter · #26 ·
im sure the stock center speaker wouldnt blend well at all but that maybe one matched to the new setup would help the sound stage since its closer to ear level. what do you think?

ive searched and havent found to much detail on the upgraded pioner system. With having a nice sub in the trunk should I compleatly remove the 6x9 subs froom the rear deck to help the sound enter the cabin area?
You can try removing the 6x9 subs and seeing how it all sounds.

I personally wouldn't use a center channel either way. You could try it and see how it works, and I can give you a few recommendations for exactly what replacement speaker to use, but I wouldn't be able to guarantee any results. Too many factors at that point to worry about, the least of which is sensitivity and amplification.
 

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Discussion Starter · #29 ·
Thanks X, I think I can get a hold of those things and building your own would be more gratifying.
It sure is. Learning something in the process makes it much better as well. I'll make a good post on building a sub box later in this thread so you'll have an idea of what's involved.
 

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Discussion Starter · #30 ·
ill probably leave the center channel out then. with this setup the rear 6x9's would serve no porpous right?
Well, they add more bass, but you have to make sure it's in-phase with the subwoofer's bass. It also depends on how high you're crossing your subs. I have the impression that the 6x9 subs in the Pioneer system play relatively high, perhaps up to 150hz. There aren't very many subwoofers that can play that high cleanly and with great transient response. Try it with and without the 6x9 subs and see how you like it.
 

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Discussion Starter · #32 ·
good idea, ill do that. Those morel tweets are seeming hard to find what is another option that would have the same quality and responce or better.
You won't get much better response than that tweeter. Believe me, I looked for a while, and the options are very few in the size that will fit behind that door pillar and also have the ability to cross that low. The replacements for that model from Morel are $117 apiece, so you won't be getting that kind of performance for cheap. I got lucky when I got them for $60 shipped for the pair. A fellow over on techtalk.parts-express.com was very generous when he made me the offer after seeing that I was looking for a good tweeter for the Cruze.

That said, I did find this tweeter, which I would consider to be the next best thing. Sensitivity is a tad bit lower, but you should be able to use a relatively low crossover point. Somewhere around 1800-2000 should work for this tweeter.

Morel MDT 12 1-1/8" Neodymium Tweeter 277-060

I'd take the pillar covers off first and measure to make 100% sure that you'll be able to fit it in there. I don't think there will be an issue, but double check before buying.
 

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Tang Band 25-1719S 1" Ceramic Dome Tweeter 264-865

What about those? The frequency response is much lower then the morels. But then so is the RMS and Max power. They Max out around the same as the Dayton woofers. I'm hoping to keep the crossover point around 1000 What do you think?

I'm guessing your plan was to allow the sub amp to control the crossover point for the sub? How much of a difference do you think it would make if I added a DSP to the sub?

What plugins are you using for the mini DSP?
 

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Discussion Starter · #34 ·
Tang Band 25-1719S 1" Ceramic Dome Tweeter 264-865

What about those? The frequency response is much lower then the morels. But then so is the RMS and Max power. They Max out around the same as the Dayton woofers. I'm hoping to keep the crossover point around 1000 What do you think?

I'm guessing your plan was to allow the sub amp to control the crossover point for the sub? How much of a difference do you think it would make if I added a DSP to the sub?

What plugins are you using for the mini DSP?
That tweeter uses a wider faceplate and I don't trust TangBand tweeter frequency response charts. They are almost always horribly inaccurate. I usually have to measure them myself. It's not a bad tweeter, but it won't cross as low as the description would lead you to believe. I also prefer silk dome tweeters for the sound they produce.

Mostly, I don't trust the frequency response so you'd have a harder time dialing it in without a measurement microphone, and you'd have to trim the faceplate as it's wider than the Morel I posted.

I'm using the one titled "Stereo Graphic EQ plug-in."

A crossover point of 1000hz is very optimistic. I don't think I'll even be able to hit that with the Morels I'm using.

I am indeed using the amplifier to set the crossover for the sub. That won't require anywhere near as much precision, so I'll be able to do it without needing a MiniDSP. You won't gain much at all from using the MiniDSP for the sub.
 

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Ok, i orderd the Morels and the Daytons. I didnt think a DSP would make that much of a differnce with the sub. Ive decided that I'm gloing to just run new wire to the front. Might as well do it right if i'm going to do it plus I shouldnt have to cut any stock wires or plugs this way. Any other sugestions for getting the best sound out of this car?
 

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Discussion Starter · #36 · (Edited)
Ok, i orderd the Morels and the Daytons. I didnt think a DSP would make that much of a differnce with the sub. Ive decided that I'm gloing to just run new wire to the front. Might as well do it right if i'm going to do it plus I shouldnt have to cut any stock wires or plugs this way. Any other sugestions for getting the best sound out of this car?
Yeah, see my section on sound deadening. If you're doing anything with speakers, sound deadening is a must. Get it done right and you will be very, very glad you did. I posted Don's contact info over at SDS. Shoot him an email and he'll get you a quote for everything you need. Tell him Andrei sent you.

I also just pulled the trim piece off of the pillar to see how much room is back there. I'll need cut part of the end of my Morel tweeters and make that chamber a tad bit smaller (will probably raise resonant frequency a bit), but the ones I posted should fit without needing to be trimmed. The faceplate might need to be trimmed on the edges and you'll probably end up having to glue it into place.
 

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I always deadin a new vechicle. I loved his write ups. i'll admit that i belonged to the cover everything with soundmatting mindset. Glad I read his work. It explained alot and answered a bunch of questions that I've had. Thanks for all the information and help, My Explorer was the last install I did and that was 7 years ago. I still have it, just couldnt trade it in when i finnaly bought my Cruze last month. I installed an explise AVN-5435 coverd every bit of her in sound matt, sealed her up nice and tight, and put focals front and rear. I did skimp on the sub though, I went with two Alpine 10" type R's. 7 years latter she still sounds good. I hoping to just leave the Cruze stock but its starting to bug me more and more. ohh well. I'm looking forward to reading your sub box how to..
 

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Discussion Starter · #39 ·
I've been looking and I cant find a IDQ15, I have found a few IDQ12 d4 V.3, How would one of those compair against the 15 in this setup?
IDQ15 V2 subs are very hard to find. Actually, IDQ V2 subs of any size are hard to find. Those who have them and know what they've got generally don't let them go. The V3 IDQ drivers are also excellent SQ subs. I'd highly recommend them.

The closest thing you can get to an IDQ V2 driver brand new is an Arc Audio Arc10 or Arc12. Very nice subs. Those were made by Image Dynamics based on the IDQ V2 design, but with a stronger motor and more excursion. I installed on in my buddy's Cobalt and he loves it. Very clean, very tight, very accurate. For the price though if you were getting it new, I'd go with an IDQ V3.
 
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