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Discussion Starter · #1 ·
Ok all of you audio experts. I'm going to get an amp and sub. I have some amp questions that I'm hoping someone can answer for me. I have searched the web and can't find any definitive answers.

I have read several places about the differences between class D and class AB amps. I haven't found anywhere that explains which is better in what circumstances (at least in terms that I can understand).

Also, how does getting a dedicated sub amp compare to buying a 2 channel amp and bridging it.

Assuming it matters, I prefer sound quality to sheer volume. I expect to be looking in the 300 watt area. I'm not looking to rattle the doors, just take some of the work off my door speakers and fill in the bass.
 

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The class of amplifier is really what percent of the sign wave is reproduced by the output transisters. If you have a class A amp. the input signwave is reproduced just like the output signwave. All 360 degrees of the signal is amplified, in a class B, it something like 75% of the original signwave is reproduced. The class D is something like 25%.
The higher the class, (A) being the highest, the more heat and power you will burn. The lower class, like (D), the less heat and power it will burn. Both have advantages and disadvantages, but most companies are now using class D's or even less to power subs. These will draw less current at a given wattage, requires a smaller power supply and produce less heat keeping the amp cooler.
 

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I got the MTX Terminator sub/amp combo. The amp is a mono one and honestly man it slams hard with the subs. I used to think I needed a stronger amp but I had the people who hooked it up re-wire it with better wiring and wow, amazing. I honestly can't see having a more powerful amp, the car might start falling apart from the mega bass. This is what I have right now.

Amazon.com: MTX TNP212D2 Dual 12" Subwoofer And Amplifier: Car Electronics
 

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Discussion Starter · #4 ·
The class of amplifier is really what percent of the sign wave is reproduced by the output transisters. If you have a class A amp. the input signwave is reproduced just like the output signwave. All 360 degrees of the signal is amplified, in a class B, it something like 75% of the original signwave is reproduced. The class D is something like 25%.
The higher the class, (A) being the highest, the more heat and power you will burn. The lower class, like (D), the less heat and power it will burn. Both have advantages and disadvantages, but most companies are now using class D's or even less to power subs. These will draw less current at a given wattage, requires a smaller power supply and produce less heat keeping the amp cooler.
So what about sound quality then? Or is there no real rule I can follow because it varies from amp to amp. I was reading a review of a smaller Boston Acoustics amp that was class D and the reviewer said that it didn't have a lot of the distortion that is common to many class D amps. I was surprised to read that since most sub amps tend to be class D. Maybe that is just a quality issue for cheaper brands though.

Unfortunately, I didn't win the Boston. Crutchfield recommended a JL jx250/1 which is class AB. I asked about bridging vs. monoblock because I saw a Polk PA330 (also class AB) open box for cheap at a local BestBuy.

I guess my question boils down to this. Given 2 amps from respected manufacturers that have similar power and cost should I use class D vs AB as a deciding factor or don't worry about it. Should I also include bridgeable 2 channel amps in my search or just focus on monoblocks?
 

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So what about sound quality then? Or is there no real rule I can follow because it varies from amp to amp. I was reading a review of a smaller Boston Acoustics amp that was class D and the reviewer said that it didn't have a lot of the distortion that is common to many class D amps. I was surprised to read that since most sub amps tend to be class D. Maybe that is just a quality issue for cheaper brands though.

Unfortunately, I didn't win the Boston. Crutchfield recommended a JL jx250/1 which is class AB. I asked about bridging vs. monoblock because I saw a Polk PA330 (also class AB) open box for cheap at a local BestBuy.

I guess my question boils down to this. Given 2 amps from respected manufacturers that have similar power and cost should I use class D vs AB as a deciding factor or don't worry about it. Should I also include bridgeable 2 channel amps in my search or just focus on monoblocks?
I would just go Class D (Digital). You won't have to worry about changing your alternator or adding a battery. It all really comes down to budget. Give me a budget and what speaker you plan to run then I will recommend something.
 

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Discussion Starter · #6 ·
What I have in my Xb now is the stock Pioneer Avic 900bt headunit, a Polk PA660 4-channel (I think 75-80 watts rms) with lower end Boston Acoustic 6.5" components in front with Alpine coax. in the rear doors. As I said, I don't want to shake anything apart or wake the neighbors. I do like to turn it up when I'm in the car alone though. I'm mostly listening to rock from 60's to current.

My biggest problem is I like to buy quality brands that will work well and last, but I have a tight wallet. So I end up buying entry level or used equipment. I'd like to be able to get by spending a few hundred if possible.

Crutchfield recommended an Infinity basslink. I don't want a box sitting in my cargo area. I've also read of reliability issues with the basslink. When I asked for components, they suggested the JL JX250/1 and an Infinity 1062w sub. That would set me back about $300 which I can live with. I plan to either build a sealed box for under the passenger seat (will that be uncomfortable for the person sitting over it?) or I may try my hand at building a fiberglass enclosure for the passenger side cavity in the cargo area (where the JL stealthbox would go).

I see a ton of Alpine MRP-M500's on eBay going for about $85. I'm a little suspicious of their reliability/quality though since everyone seems to the selling theirs!

Any suggestions would be greatly appreciated.

BTW I saw the picts of your build and am in AWE! Spectacular work!
 

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What I have in my Xb now is the stock Pioneer Avic 900bt headunit, a Polk PA660 4-channel (I think 75-80 watts rms) with lower end Boston Acoustic 6.5" components in front with Alpine coax. in the rear doors. As I said, I don't want to shake anything apart or wake the neighbors. I do like to turn it up when I'm in the car alone though. I'm mostly listening to rock from 60's to current.

My biggest problem is I like to buy quality brands that will work well and last, but I have a tight wallet. So I end up buying entry level or used equipment. I'd like to be able to get by spending a few hundred if possible.

Crutchfield recommended an Infinity basslink. I don't want a box sitting in my cargo area. I've also read of reliability issues with the basslink. When I asked for components, they suggested the JL JX250/1 and an Infinity 1062w sub. That would set me back about $300 which I can live with. I plan to either build a sealed box for under the passenger seat (will that be uncomfortable for the person sitting over it?) or I may try my hand at building a fiberglass enclosure for the passenger side cavity in the cargo area (where the JL stealthbox would go).

I see a ton of Alpine MRP-M500's on eBay going for about $85. I'm a little suspicious of their reliability/quality though since everyone seems to the selling theirs!

Any suggestions would be greatly appreciated.

BTW I saw the picts of your build and am in AWE! Spectacular work!
Thanks...

What do you listen to?
 

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Discussion Starter · #8 ·
I listen to rock anything from the 60's to today (beatles, stones, bowie, ac/dc, greenday, U2, Cage the Elephant, afi, ...)
 

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Discussion Starter · #10 ·
I've bought from sonicelectronix before. The do have really good prices. Thanks for the recommendation!
 

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I've bought from sonicelectronix before. The do have really good prices. Thanks for the recommendation!
The bass will not bother the passenger under the seat.... You really cant go wrong with the XD series...they stay cool, very reliable, sound great, they don't draw too much power and they are tiny.
 
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