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Discussion Starter #1
Ok so I am not an audiophile by ANY means, but I would like to add some low end kick to my CRX without using up much room and as cheap as possible.

As a baseline for my goals, I would be happy if my system could sound as good as my wifes 2007 ford escape hybrid with the factory mach speaker system, including the single 8" sub. She has this aftermarket head unit: Digital Media Receiver - KD-X250BT - Introduction. So I dont think this goal is super lofty.

So I figure I will need a bit more power to sound as good as her car, since obviously my CRX has a lot more road noise. I think I can mount 8" subs in the factory rear speaker locations and enclose them and throw in some filling for a sealed box. I currently have the same head unit as my wife.

I was considering 2 of these subs:
https://www.amazon.com/gp/product/B00IVEHFNC/ref=ox_sc_sfl_title_3?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

They are dirt cheap, have decent reviews, and they are not made of paper and foam, which was a concern of mine since CRXs do leak sometimes, and I wanted a sub that wasnt going to come apart with a little dampness or humidity.

I was considering this amp, because it is also cheap and has decent reviews, and seems like the power output is about right for 2 of the above subs running at 2ohms: https://www.amazon.com/gp/product/B004S4XNEO/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

And I would wire them like this:


So I realize this is all completely below the grade of what most people here would consider, but keep in mind my budget and goals are extremely modest.

Assuming I can make decent enclosures out of the stock rear speaker locations, are there any other glaring problems with my plan? Or ideas for how it could be substantially better without spending much more money?
 

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the power ratings on all of that equipment is absolute bogus.

You'll ave a hard time making enclosures for anything bigger than a 6.5 in the stock rear speaker locations.

Hell, I'd sell ya the Alpine MRV-M500 I have sitting around for a decent price that would blow that Boss amp away in every aspect. You'd just have to decide what you want to do about drivers. A bass tube like a Bazooka actually works really well for an Easy Button solution,but they do take up some space.

You can probably get some decent drivers from Parts Direct in all honesty.
 

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the artist formerly known as drexelstudent11
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the rated power output on cheap amps is usually about as accurate as lawnmower horsepower ratings were 10 years ago - meaningless.

I like how that "1100" watt amp has a 15amp fuse - 14.1vx15a=211.5 watts at 100% efficiency - it's really a 150watt amp with a really optimistic rating.


the first review even breaks it down!
Style Name: 1100 watt Class A/B Monoblock Verified Purchase
I'm an electronics engineer so I care about specifications. This amplifier is a low cost item which offers reasonable value, but I wish they would be more honest with their claims.

My measurements show 21.5V rms continuous into 4 ohms at the onset of clipping with a 14.12V supply. This is 115W rms.
With no load it gives 23.9V with 14.12V supply. This corresponds to 142W rms peak.

So, essentially it is a 100-150W amp (4 ohms), or at best 200-300W (probably less) into 2 ohms. The claims of 250W into 4 ohms or 1100W into 2 ohms are at best ridiculously optimistic.

I would suggest that it is worth paying a bit more to get something better.
I've got one of these in my s2000, and it does alright, but it's behind the passenger seat in a really compromised install.

https://www.amazon.com/Rockville-RW8CA-Profile-Under-Seat-Subwoofer/dp/B019Z3RFGY/ref=sr_1_15?s=car&ie=UTF8&qid=1473122520&sr=1-15&keywords=rockville+8"

if I had more space, I'd definitely have gone with this one:
https://www.amazon.com/Rockville-RW10CA-Profile-Powered-Subwoofer/dp/B019Z3R582/ref=sr_1_3?s=car&ie=UTF8&qid=1473122576&sr=1-3&keywords=rockville+10"

what's nice about those is they include the install kit which is ~$20 by itself, and it's decent quality. They're also fairly small so you don't have a huge box taking up limited space.
 

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the artist formerly known as drexelstudent11
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oh, also always look for CEA 2006 compliance on any amp you're looking at - it means it was tested by a 3rd party so they can't bullshit the ratings like the boss/lanzar/planet audio/soundstorm/pyle garbage does
 

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Discussion Starter #5
the power ratings on all of that equipment is absolute bogus.
the rated power output on cheap amps is usually about as accurate as lawnmower horsepower ratings were 10 years ago - meaningless.
Yea, I understand that they are wildly overestimating the power output of those cheap components, but I was kind of depending on that. I figured the "1100W" amp and the 2 "1200W" subs would probably be ok with each other, and like you said, probably pull about 200 watts, which is about all I would ask from my stock alternator.

As a side point though, and forgive me because my understanding of how class A/B or D amps works is shady at best, but I thought class D amps were often rated higher than their actual output, because the way they function is so much more efficient than class A/B amps. It was my understanding that class D amps are often rated at what a class A/B amp that puts of the same volume on the same drivers would be rated at, so consumers would be able to compare equivelent amps. Much in the same way that LED or compact flourescent bulbs include a wattage rating that is far higher than their actual draw, so you can compare the light output to much less efficient incandecent bulbs.

That could all be total BS though, as I said I am by no means an expert on this stuff.


Hell, I'd sell ya the Alpine MRV-M500 I have sitting around for a decent price that would blow that Boss amp away in every aspect.
If you are thinking around $50 I might very well take you up on that.

I've got one of these in my s2000, and it does alright, but it's behind the passenger seat in a really compromised install.

https://www.amazon.com/Rockville-RW8CA-Profile-Under-Seat-Subwoofer/dp/B019Z3RFGY/ref=sr_1_15?s=car&ie=UTF8&qid=1473122520&sr=1-15&keywords=rockville+8"

if I had more space, I'd definitely have gone with this one:
https://www.amazon.com/Rockville-RW10CA-Profile-Powered-Subwoofer/dp/B019Z3R582/ref=sr_1_3?s=car&ie=UTF8&qid=1473122576&sr=1-3&keywords=rockville+10"

what's nice about those is they include the install kit which is ~$20 by itself, and it's decent quality. They're also fairly small so you don't have a huge box taking up limited space.
I do really like the look of those, and I had no idea they existed, so thanks for bringing them to my attention! I will have to go out to the CRX with a tape measure soon and look and see what I could cram in there somewhere out of the way.

Thanks guys, you have definately given me some stuff to think about!
 

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Yea, I understand that they are wildly overestimating the power output of those cheap components, but I was kind of depending on that. I figured the "1100W" amp and the 2 "1200W" subs would probably be ok with each other, and like you said, probably pull about 200 watts, which is about all I would ask from my stock alternator.

As a side point though, and forgive me because my understanding of how class A/B or D amps works is shady at best, but I thought class D amps were often rated higher than their actual output, because the way they function is so much more efficient than class A/B amps. It was my understanding that class D amps are often rated at what a class A/B amp that puts of the same volume on the same drivers would be rated at, so consumers would be able to compare equivelent amps. Much in the same way that LED or compact flourescent bulbs include a wattage rating that is far higher than their actual draw, so you can compare the light output to much less efficient incandecent bulbs.

That could all be total BS though, as I said I am by no means an expert on this stuff.
It's BS.

D class amplifiers are vastly more efficient, but the output volume of a given driver is directly related to the input power. D class architecture doesn't break the rules of electrical power.

If you only have 211 watts of available input power, the you only have a maximum of 211 watts available for output power. Otherwise you would be breaking the law of conservation of energy or the amplifier somehow uses an endothermic process that pulls heat from the surroundings and creates more power.

1100 watts of burst power would require 78 amps of current. I don't think a standard 15 amp fuse can withstand that even for a short burst.

If you are thinking around $50 I might very well take you up on that
Yeah, not really looking to let it go quite that cheap.
 

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Discussion Starter #7
You are talking about a fixed output, but when you get into PWM stuff, that isnt always how it works. In some circumstances being on 50% of the time can have a similar effect to being on 100% of the time if the cycles are fast enough.

Not saying you are wrong about those numbers being based far more on marketing than anything to do with reality.
 

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I haven't looked into the specifics of why class D are more efficient than A/B amps, but I have owned both and D's draw much less current than it's equivalent a/b. The A/B class will push the power, but at a greater inefficiency. ( and this is from a electrical engineer)
 

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Rockford Fosgate makes a budget amp. called the prime series. not as expensive as the punch series but still has the same reliability and power output as its big brothers. I have the 500 watt mono amp and it's rated at 642 watts rms @2 ohms. Came with a certificate showing actual power output as all Fosgate amps do. it's closer to 300 rms at 4ohms. check my crv audio build thread. also I only spent 120 bucks to buy it.
 

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Discussion Starter #10
I haven't looked into the specifics of why class D are more efficient than A/B amps, but I have owned both and D's draw much less current than it's equivalent a/b. The A/B class will push the power, but at a greater inefficiency. ( and this is from a electrical engineer)
As I said, I am NOT an expert, but from my understanding Class A amps are basically on at full power all the time, where as class Class D amplifiers rapidly switch output on and off via PWM.

For me I think of it like lights switches, a Class A would be a bulb cover, so the bulb is always lit, but the light is only visible when uncovered. Whereas a Class D would be an actual switch that turns off the power when the light is not needed.
 

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Discussion Starter #12
I would suggest reading these if you actually want a basic understanding of the difference between different audio power amplifier types.

A primer on audio power amplifier classes.


Class A amplifier operation primer.
"Class A Amplifier To achieve high linearity and gain, the output stage of a class A amplifier is biased “ON” (conducting) all the time. Then for an amplifier to be classified as “Class A” the zero signal idle current in the output stage must be equal to or greater than the maximum load current (usually a loudspeaker) required to produce the largest output signal."

"Class D Amplifier A Class D audio amplifier is basically a non-linear switching amplifier or PWM amplifier."

I feel that is pretty much what I said in my last post.
 

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Discussion Starter #14 (Edited)
I am not trying to be snarky or anything, as I said before I really dont claim to know this stuff that well, so if what I said was wrong or I am not understanding it correctly I am always open to correction.

However, since we were discussing how class D amps work differently than more traditional amps, I would suggest that the article you linked is a poor choice for that comparison, as they plainly state their bias:

"The most commonly constructed amplifier classes are those that are used as audio amplifiers, mainly class A, B, AB and C and to keep things simple, it is these types of amplifier classes we will look at here in more detail."

Since they dont even feel class D amps are a valid audio amplifier choice, they dont do more than talk about them in passing, which I assume means that is a fairly old article, although I didnt see a date on the mobile version of it to confirm.
 

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If you are looking for cheap, what I have set up currently may work alright.

I have a '91 CRX, and am using a $99.00 Dual 300W powered (amp built in) 10" subwoofer, with a $30 set of 6.5" Sony Xplodes in the rear, powered by a $60 Dual 600W amplifier.

Not insanely expensive, nor is it all that powerful. It does bring a little bit of bass to my small car. The $60 amp only serves to allow me to turn my stereo up without the speakers distorting. Otherwise, my set up is nothing fancy, and doesn't even sound as good as more expensive ones. But, it works for me.
 

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I'm still rockin a Treo 10" competiton sub powered by a logic 500w amp. All in a prefab ported box and the sound is awesome, with room to really push it if I ever felt the need to. Didn't break the bank and sounds awesome some 7 years later!
 

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Discussion Starter #17 (Edited)
I have to set aside the bass for right now, with my new car I need some 6.5" door speakers. Any suggestions in the sub $40 range on amazon? I want something fairly weather resistant, because water can definately get into CRX doors, so definately no paper cones or foam surrounds, possibly even marine speakers.

These will be driven ampless directly off my head unit, so efficency is more important than power handling, 20 watts RMS, 50 watts max is my jvc head unit.
 

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Discussion Starter #18 (Edited)
Here is some of the ones I am looking at on amazon, any thoughts or opinions on any of these? as I said these will be driven off a 20w RMS 50w max JVC head unit into the forseeable future, although I might get an amp down the road:

$22: https://www.amazon.com/Kenwood-KFC-1665S-300-Watt-6-5-Inch-Speakers/dp/B00HZVHA1E/ref=sr_1_1?ie=UTF8&qid=1474287897&sr=8-1&keywords=KFC-1665S

$35: https://www.amazon.com/DUB-DUBs265-6-5-Inch-Coaxial-Speaker/dp/B00UZP6U0O/ref=sr_1_1?ie=UTF8&qid=1474287877&sr=8-1&keywords=DUBS265

$40: https://www.amazon.com/Clarion-SRG1623R-80-Watt-6-5-Inch-Speakers-Set/dp/B00I9RLO24/ref=sr_1_1?ie=UTF8&qid=1474287916&sr=8-1&keywords=SRG1623R

$40: https://www.amazon.com/Pioneer-TS-A1676R-6-5-Inch-3-Way-Speaker/dp/B014Z7ILY0/ref=sr_1_1?ie=UTF8&qid=1474288125&sr=8-1&keywords=TS-A1676R

$37: https://www.amazon.com/Sony-XSFB1630-Audio-Speaker-Black/dp/B00TM98RWI

Those last Sonys have some pretty good package deals too:

$58 for 4 x 6.5" : https://www.amazon.com/Sony-XS-FB1630-Speakers-Stereo-XSFB1630/dp/B00UT3SKBY/ref=sr_1_2?ie=UTF8&qid=1474287943&sr=8-2&keywords=XS-FB1630

$69 for 2 x 6.5" and 2 x 6x9": https://www.amazon.com/Sony-XS-FB1630-6-5-Inch-6-9-Inch-Speakers/dp/B016IN0WEG/ref=sr_1_3?ie=UTF8&qid=1474287943&sr=8-3&keywords=XS-FB1630

Unless I can find something better, I will also likely be getting one of the 10" Rockville subs when I can afford it: https://www.amazon.com/Rockville-RW10CA-Profile-Powered-Subwoofer/dp/B019Z3R582/ref=sr_1_3?s=car&ie=UTF8&qid=1473122576&sr=1-3&keywords=rockville 10"&tag=vs-auto-convert-amazon-20


EDIT: Here are the links for the same speakers off Crutchfield with the actual specs:

Kenwood: http://www.crutchfield.com/p_1131665S/Kenwood-KFC-1665S.html?nvpair=YCSpeaker_Size|6+1/2&nvpair=FFSensitivity|[rank3]90+-+91dB&nvpair=FFSensitivity|[rank4]Over+91dB

Jensen: http://www.crutchfield.com/p_110DUBS265/Jensen-DUBS265.html?nvpair=YCSpeaker_Size|6+1/2&nvpair=FFSensitivity|[rank3]90+-+91dB&nvpair=FFSensitivity|[rank4]Over+91dB

Clarion: http://www.crutchfield.com/p_020SRG1623/Clarion-SRG1623R.html?nvpair=YCSpeaker_Size|6+1/2&nvpair=FFSensitivity|[rank3]90+-+91dB&nvpair=FFSensitivity|[rank4]Over+91dB

Pioneer: http://www.crutchfield.com/p_130TA1676R/Pioneer-TS-A1676R.html?nvpair=YCSpeaker_Size|6+1/2&nvpair=FFSensitivity|[rank3]90+-+91dB&nvpair=FFSensitivity|[rank4]Over+91dB

Sony: http://www.crutchfield.com/p_158FB1630/Sony-XS-FB1630.html?nvpair=YCSpeaker_Size|6+1/2&nvpair=FFSensitivity|[rank3]90+-+91dB&nvpair=FFSensitivity|[rank4]Over+91dB
 
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