Can I add an amp to Honda head unit (stereo) ?

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I have a 2006 Accord, I want to keep the factory head unit and add a 2 channel Sony amp from my old car, also install better door/rear speakers.

Is it possible to keep the factory CD player, or do I have to buy an aftermarket head unit ?
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Any suggestions on decent speakers (same size/location) to replace the original speakers.
 
Factory head unit replacement is a PITA in these cars!

What two channels do you want to push with the amp? Obviously, if you want to push the rears and your amp has speaker level inputs it's a really easy install. Otherwise I'm not sure what outputs the factory head unit has if you want to push the fronts.
 
It would be much easier to just get an aftermarket replacement and keep the old parts for when/if you sell it. Of course, I'm sure with some crossovers you could do what you want without an unholy amount of fuss.
 
You should know what kind of output driver your factory head unit has.

Amplifiers capable of driving speakers, i.e. an audio amplifier, are not all the same and are not necessarily compatible with speaker level inputs to typical car stereo amplifiers.

For example, my RX8's head unit amplifier outputs are differential and you'd not want to directly drive speaker level inputs with it. I'd say this isn't the norm, but you'd want to know with your specific case.

On the other hand they might try to sell you what is often unnecessary equipment when you inquire on this subject (like a 300 dollar unit which "flattens" the response of EQ's factory audio systems (EQ'd to keep bass out of cheap speakers???, who knows).
 
Not sure if yours is the same as my '06 TL or not.

If you're just amping a sub, you can tap into the factory sub wire and run it to the high level input of the amp. If you don't have a high level input on the amp you have to run factory speaker output to a line output convertor and then to the amp.

If you're amping the mids and highs, you have to pull the signal at the factory amp behind the passenger kick panel. I used factory wiring for a while but it sounds better with larger wiring especially at higher volumes.

I run two amps, one for the subs and one 6 channel JL amp for the mids/highs. One thing I learned quickly was the class D 1,200 watt amp for the subs pulls much less power at normal volumes than the class AB for the mids/highs. You won't believe how much better the factory speakers will sound with an aftermarket amp.
 
I forgot, if you're upgrading the front stage, check out the Image Dynamics CTX65CS. There is nothing at that price point that comes close. The silk dome tweeters are very detailed but not harsh at all. I can listen to it loud for hours and not get fatigued. The mids look like small subs and deliver excellent midbass. I've listened to many, many competition level cars and these $175 components sound better than some $600 sets. I'm also running 175 watts a piece rms and have even run them full frequency and they handle it just fine.
 
You can always use a line level converter but most of these are cheaply built and noisey! Best to replace the head unit unles it has RCA or some other low level output from the factory you can tie into. Most OEM head units other then the ones that come with navigation built in are usualy around the $25 price point so you almost always get a better tuner and amp and other features in an aftermarket head unit unless you are talking some high end models like Lexus,ROlls Royce etc......Oh and if youneed to lube anything inside I like Swiss single cut watch oils!
 
Originally Posted By: JohnBrowning
You can always use a line level converter but most of these are cheaply built and noisey! Best to replace the head unit unles it has RCA or some other low level output from the factory you can tie into. Most OEM head units other then the ones that come with navigation built in are usualy around the $25 price point so you almost always get a better tuner and amp and other features in an aftermarket head unit unless you are talking some high end models like Lexus,ROlls Royce etc......Oh and if youneed to lube anything inside I like Swiss single cut watch oils!


These stock headunits have extremely good sound quality. We've had a couple guys win SQ competitions with the stock head unit.

I've got a primarily SQ setup and it sounds extermely clean with LOCs. I've heard of other brands having issues with these but not in the TL or Accord. I'm getting ready to try it going straight from the headunit using the low level outputs and no LOCs to see if there's a difference but it's hard to imagine.

Off topic but where did you go?
 
I believe JL Audio makes a OEM interface called the Cleansweep which will allow you to keep the OEM deck but run aftermarket amps, speakers and subs.
 
Originally Posted By: nthach
I believe JL Audio makes a OEM interface called the Cleansweep which will allow you to keep the OEM deck but run aftermarket amps, speakers and subs.


They do. Not a lot of people run it anymore becuase it's not necessary as originally thought to retain HFL and Navi voice. The upper 5% SQ competitors run processors for that little extra but the frequency response of the stock system is nearly flat so it's a great platform to add aftermarket components.
 
Originally Posted By: digitalSniperX1

For example, my RX8's head unit amplifier outputs are differential and you'd not want to directly drive speaker level inputs with it.


Practically all head unit amplifier outputs these days, save for very cheap ones, are differential (push-pull, balanced transformerless, non-common grounded).
 
As you said, and overwhelmingly, most power amplifier outputs are push-pull, two sets of output devices driving opposite sides of the waveform, but NOT simultaneously.

However, in this configuration the outputs are said to be complimentary (not differential....although push pull can be differential).

Differential amplifiers have two output devices also, but they continuously drive in opposing polarities to each other, with what I'll call a "non-physical ground". "assumed ground" or "virtual ground" between them.

The "best" audio amplifiers are class A (and I loosely use the term best as I don't necessarily agree). Class A amplifiers have a maximum efficiency, at the output stages of 25% (the output devices drop considerable voltage while passing considerable current which is power dissipated as heat, not acoustical energy).

Class A can be push-pull, differential, or single ended.

Typical push-pull amplifiers are biased class AB, with a maximum output device efficiency of 78.5%...which is why they are predominant.


Ok, I've beat the dead horse long enough. Hopefully I'm right (its' been a long time).
 
Last edited:
Originally Posted By: digitalSniperX1
As you said, and overwhelmingly, most power amplifier outputs are push-pull, two sets of output devices driving opposite sides of the waveform, but NOT simultaneously.

However, in this configuration the outputs are said to be complimentary (not differential....although push pull can be differential).

Differential amplifiers have two output devices also, but they continuously drive in opposing polarities to each other, with what I'll call a "non-physical ground". "assumed ground" or "virtual ground" between them.

The "best" audio amplifiers are class A (and I loosely use the term best as I don't necessarily agree). Class A amplifiers have a maximum efficiency, at the output stages of 25% (the output devices drop considerable voltage while passing considerable current which is power dissipated as heat, not acoustical energy).

Class A can be push-pull, differential, or single ended.

Typical push-pull amplifiers are biased class AB, with a maximum output device efficiency of 78.5%...which is why they are predominant.


Ok, I've beat the dead horse long enough. Hopefully I'm right (its' been a long time).


Are you sure about the efficiency? The AB I have is hot when it's on whether there's music playing or not. The class D for the subs is always cool. It puts out twice the power of the AB amp yet draws about the same at full volume. I've always heard a class D can't go above 300hz so it's useless as a mid/high amp but it's the most efficient at 90% or greater. I ran an AB for the subs with less power and it dimmed the headlights at less volume. The class D doesn't.
 
Class D has the highest efficiency, no doubt about it. Can be over 90%. The reason is simple if you understand the basics.

A class D amplifer essentially converts the audio signal into a pulse train. That pulse train is used to turn on "hard" (meaning out of the linear region) a pass transistor. By hard I mean it's (the pass transistor) essentially a short circuit across its output terminals so no voltage drop = no power consumed, irrespective (ideally) of load current. That output pulse train is low pass filtered to remove harmonics that are not part of the original input signal.

To understand all the math involved is fairly complex (not overly). But I think what I said is essentially true.

As per the 78.5% efficiency.. this is the MAX efficiency...where the output devices are essentially in class B bias. Typical class AB would probably be significantly less, perhaps 50%.

As an example, I owned an Adcom GFA-5500 which had 5 output devices per complementary side (totalling 20 output transistors). It's idle current (bias or quiescent) current was high. Without a watt delivered to the speakers, it was running some 50 watts of static power dissipation. It's efficiency was probably under 50% at max output power (but certainly over 25%).


Added:

I'm sure the low pass filter design gets a bit more complex (and expensive) in higher frequency class D, but I don't see a reason why a class D amplifier is limited to bass frequencies. Higher frequencies will require the pass transistor to switch at a much faster rate, which will increase power lost in it (switching between off and on takes time and during that transient it will be dropping voltage hence dissipating power). Also, in class D (switching or "digital") the input circuit will dissipate more power as the transistor's gate (input terminal) has considerable capacitance that dumps current (when turned off) into resistive loads (input circuit resistors for example).

Hopefully, I stated this well enough for you to make use of it.
 
Originally Posted By: digitalSniperX1
Class D has the highest efficiency, no doubt about it. Can be over 90%. The reason is simple if you understand the basics.

A class D amplifer essentially converts the audio signal into a pulse train. That pulse train is used to turn on "hard" (meaning out of the linear region) a pass transistor. By hard I mean it's (the pass transistor) essentially a short circuit across its output terminals so no voltage drop = no power consumed, irrespective (ideally) of load current. That output pulse train is low pass filtered to remove harmonics that are not part of the original input signal.

To understand all the math involved is fairly complex (not overly). But I think what I said is essentially true.

As per the 78.5% efficiency.. this is the MAX efficiency...where the output devices are essentially in class B bias. Typical class AB would probably be significantly less, perhaps 50%.

As an example, I owned an Adcom GFA-5500 which had 5 output devices per complementary side (totalling 20 output transistors). It's idle current (bias or quiescent) current was high. Without a watt delivered to the speakers, it was running some 50 watts of static power dissipation. It's efficiency was probably under 50% at max output power (but certainly over 25%).


Added:

I'm sure the low pass filter design gets a bit more complex (and expensive) in higher frequency class D, but I don't see a reason why a class D amplifier is limited to bass frequencies. Higher frequencies will require the pass transistor to switch at a much faster rate, which will increase power lost in it (switching between off and on takes time and during that transient it will be dropping voltage hence dissipating power). Also, in class D (switching or "digital") the input circuit will dissipate more power as the transistor's gate (input terminal) has considerable capacitance that dumps current (when turned off) into resistive loads (input circuit resistors for example).

Hopefully, I stated this well enough for you to make use of it.



Thanks!

I've heard that class D amps are just now becoming capable of higher frequencies or are going to be capable soon. Maybe it was that the SQ wasn't up to par, I can't remember.

Do you know much about sub enclosures? I tried something new, could never get the sealed box to sound right in my car, not to mention the rattles associated with the box firing into the trunk.

I had a bandpass box designed by the JL engineers for my specific car and of course using two of their 12W6 subs. It's ported through the ski pass with a bulkhead to separate it from the trunk, which takes care of the rattle issues. I had heard nothing but negatives about bandpass setups before but this is the absolute best sounding setup I've ever heard. On top of that, it's incredibly efficient. I had to cut the gains back by 1/2. The box gives nearly an 8db gain over the sealed box I had. Of course it's a narrow band but it's perfectly flat from 36hz to 90hz.
 
Hey, no problem!

I've never looked seriously into sub enclosure design but I think it's reasonably straightforward using a set of parameters called Thiele-Small applied to a set of equations. Of course one could get pretty exotic in those designs too...such as finite element analysis on the enclosure in order to design the near perfect bracing for the enclosure. I'd think the best eclosure shape would be cylindrical, or spherical for a number of reasons. Just my intuition.

I came across an excel spreadsheet some time back,
very nicely done I might add, which would do these computations and estimate frequency/phase response. I'll see if I can find that again. I'm sure there is a lot of information available, but this spreadsheet seemed to be pro-quality.

As far as getting rid of rattles, that sounds like a trial and error process. You'd want to tune to different frequencies to find them all (in search of rattling surfaces which have different resonant frequencies).

I'm almost sure the sub in my house here (a SV Sounds 20-39 PC+) is a bandpass design. I can tune it by plugging one of 3 ports. I think it sounds incredible but they are my ears, and they are not perfect.

A couple things interesting about the human ear...which relates to subs, class D designs etc. You may already be aware of this.

It turns out our ears are pretty insensitive to harmonic distortion at low frequencies. This is perhaps one reason why a class D amplifier design is more practical when driving subs vs. the complete audio spectrum. Our ears are sensitive to other waveform "irregularities" at low frequencies and are insensitive to the same irregularities at higher frequencies.

Added:

Haven't found the spreadsheet. These looked pretty good though. I'm on a linux machine here so I can't run these executables so I've not checked them out but again, this guy looks to know what he's talking about.

http://www.audiogrid.com/audio/
 
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