# Review: Kenwood x4r



## tyroneshoes (Mar 21, 2006)

I have had these amps (x4r&x1r) for about a month now so I'm able to give a decent review at this time. 

For those that dont know, this is Kenwoods run at the compact digital full range amp. What makes this amp different is that there is dsp and the most wanted features such as active crossovers, peq and time alignment built in as well. Zapco has this in their dc ref line with even more tuning options but at 3x the price. 

This amp is an answer to people who want a double din unit and also want to go active and for stock headunit users. Or people that just want to be able to choose from any headunit and still have TA and crossovers. I got these to replace a pdx 4.100 and 1.600. I liked those amps but, I had to run an active crossover in line and lacked TA. So I swapped to these.

First thing I will say is they are relatively small. Here's a pic compared to a PDX










aesthetically I like them a lot. Build quality feels solid, quiet fans, lots of aluminum and minimal plastic, connections all on one side. Nice digital readout of amperage drawn, battery voltage and temperature. My trunk does not glow blue. You control the PEQ, delay and crossover through the jog wheel and digital readout on the amp itself, no computer or palm needed. 

This will give you an idea of how the unit is used under the cover. The adjustments are very easy to set.









These are the DSP features, the dsp features are also adjustable for the line out, so you can use the dsp on whatever sub amp you want:


_
Rated Power Output(14.0V)
4Ω 100W x 4
2Ω 150W x 4
Bridged 4Ω 300W x 2
High-Pass Filter Frequency (-24 / -12 dB/oct.)	Low Range30-250Hz
High Range500-5kHz
Low-Pass Filter Frequency (-24 / -12 dB/oct.)	Low Range30-250Hz
High Range500-5kHz
Band Reject Filter	-
Band Reject Filter Frequency	-
Bass Boost Circuit	-
Delay Control	ms - 3.9 ms (.1 ms Step on all channels)
Frequency BAND 1 (Front, Rear)	25/40/60/80/100 Hz
Frequency BAND 2 (Front, Rear)	150/200/300/400/500 Hz
Frequency BAND 3 (Front, Rear)	600/800/1k/1.5/2 kHz
Frequency BAND 4 (Front, Rear)	3/4/5/6.3 kHz
Frequency BAND 5 (Front, Rear)	8/10/12.5/16 kHz
Gain (Boost or Cut)	(-9dB to +9dB)
Quality Factor BAND 1 - BAND 3	1/2/3/5
Quality Factor BAND 4 - BAND 5	2/4/8/10
Phase Inverter	° (Normal) / -180° (Reverse)
Operating Voltage	14.4 V (11 - 16 V Allowable)_

I had my pdx 4.100 switched to get all 4 channels of output from a single rca run, I was glad this amp had the same feature. However, the alpine allowed you to adjust the gain for each channel, the kenwood only allows you to adjust the gain of the input used so if this is used active on a 6.5" and tweet, you really need to use both inputs other wise your tweets will blow your ear off. There is no volume control on each channel like an active crossover or processing deck, you must adjust the gain to match levels. I got some y-adapters and it was fixed and all is well. Just one thing I wasn't too happy about. 

I am using this amp to power 7"s and tweets. The woofer (lotus ref) is lowpassed at 2k 4th order. -This amp does not have bandpass unless you use the subsonic filter which goes as high as 60hz. I used my headunit's 80 hz highpass since I like to crossover around there.

Since the mid is playing 80-2k, only 3 channels of peq were available in the playing range. However, I did use points past the playing range at 4 and 8k to create little notch filters to tame some of the undesirable aspects of the metal cones.

Compared to the PDX, I will say that I did notice a difference in sound. The PDX sounded good, but sounded a little less "dynamic" than the usual class a/b amps I was used to. I know this is a debatable topic but, I found the pdx to sound good, but a little hazy. Nothing that made the amp sound bad, but it sounded unnaturally mellow for my taste. The Kenwoods sound like the typical a/b class amp and cleaner. However, the dsp and digital crossovers can have lots to do with it. I hated the way the pdx amps looked and they really lit up my entire car blue. I could have taped the led but I digress. 

The Kenwoods sound great. I was as most kinda iffy about getting a kenwood product as I haven't thought they made a good product since the PS series of amps but I think they did a great job with these amps. They run very cool and very efficient. I have never seen them warmer than 110 degress on the readout after a long drive. 

I recommend this amp to anyone who is unable to get a headunit with processing or wants a gps/double din. The price is around $250 on ebay/million buy and that a great deal considering all these do. Overall, I'm very pleased.

If youre like me and want matching amps, the x1r is a good sub amp. I feel its a bit overrated at 1200 watts at 2 ohms but its powering my sub with no problem. It has a remote one channel sub level with a selectable q controller like a PG basscube and runs cool. This is nothing new, RF has been doing this for a while, but its nice to have. No real great dsp like the x4r so not as good as a deal IMO but still a good sub amp.


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## skylar112 (Dec 8, 2005)

Very nice review, I'm glad to hear they are decent amps.


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## 3.5max6spd (Jun 29, 2005)

Pretty cool, thanks. Very nice option to the Kicker SX /PDX's of the world. 

Any turn On/Off pops/Thumps?


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## 328iBMW (Aug 16, 2007)

Thanks for the review.


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## red03vette (Sep 3, 2007)

ya thanks for the review. well done. i have been looking at these for a little while. do you think they are capable of making their rated power?  

duce


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## t3sn4f2 (Jan 3, 2007)

the duce said:


> ya thanks for the review. well done. i have been looking at these for a little while. do you think they are capable of making their rated power?
> 
> duce


Why wouldn't they make it. It not a crappy company, pretty complete specs are provided to give a good idea that they can do. Nothing shows that they won't.


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## red03vette (Sep 3, 2007)

t3sn4f2 said:


> Why wouldn't they make it. It not a crappy company, pretty complete specs are provided to give a good idea that they can do. Nothing shows that they won't.





> If youre like me and want matching amps, the x1r is a good sub amp. I feel its a bit overrated at 1200 watts at 2 ohms


this is what may have concerned me a little. i realize it is not the same amp, but it's related.  

duce


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## t3sn4f2 (Jan 3, 2007)

It should do that at 14 volts. Efficient topology amp, with 75 amps of current draw, msrp of $600 on a model line that is not considered expensive. Everything points to that number at least for 2 ohms. It might get picky around at one ohm though at the spec'd power.


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## tyroneshoes (Mar 21, 2006)

3.5max6spd said:


> Pretty cool, thanks. Very nice option to the Kicker SX /PDX's of the world.
> 
> Any turn On/Off pops/Thumps?


No noise what so ever.


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## tyroneshoes (Mar 21, 2006)

the duce said:


> ya thanks for the review. well done. i have been looking at these for a little while. do you think they are capable of making their rated power?
> 
> duce


There is no question in my mind that the x4r produces its rated power. It certainly sounds just as powerful at the 4.100 which was 138 a channel. Oddly, theyre both (x4r, x1r)fused at 75 amps and one is 600 watts and the other 1200. The thing that threw me off is that moving from the pdx 1.600 to the x1r, I should have almost doubled my power as I have a 2 ohm sub. But I noticed very little difference. Of course this is subjective and I dont know how to test an amp without a dummy load which can be costly when youre testing for over 1000 watts. Im no pro though. I do not recommend giving it a 1 ohm load as people have blown it but these people are most likely not that great at adjusting gain. But I have never seen ratings like these before


4 ohm=600watts @ 14v
2 ohm=1200 watts @ 14v
1 ohm= Over 1000 watts @ 14v??

What's that?

Also Ive never had a really powerful amp for a sub, 600 watts was the highest I went before. I expected 1200 watts to really up performance at a lower volume and play loudly without clipping but it sounded exactly the same as the 1.600. I dont really know what to expect. I will tell you this, there is no dimming at all even playing full volume. These are running very cool running and efficient. The current used and temperature read out as well as a digital clipping indicator is a nice touch.


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## red03vette (Sep 3, 2007)

very nice, thanks for answers tyrone and t3! i really like the look of these amps especialy considering the price you can get them for.  

duce


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## DejaWiz (Sep 20, 2007)

Nice amps and great review. Thanks for taking the time to post.

Didn't CA&E mag review this a while back and state it did, in fact, make rated power?


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## LS-N-IT (Mar 5, 2008)

I was just thinking about using these amps as well.. (I have the KAC-X10 to 1-12" dvc sub right now and it gets pretty ridiculous). Im glad to see a good comparison with other good amps.. 

Eventually I may want to try 3 single 4-ohm subs on the X1R (Im starting with two of the CSS SD12s btw), have you tried running it to 1.33 ohms to see if it handles it? 

I did see one note somewhere on the web the X1R kept blowing fuses at 1 ohm, but I would venture to guess they had gains at max and had it in full clipping and then some..


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## tyroneshoes (Mar 21, 2006)

I have only run the amp at 2 ohms and it doesnt break a sweat.


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## dsg74 (Jan 7, 2008)

Anyone try the X4R bridged? I want to run a 4 way system and am considering these amps because of the TA feature. I would be using one X4R for the mids and tweets and one bridged for the midbass and a X1R for either 2 10" or a single 12". It looks like the crossovers would be flexible enough? The PEQ could be enough that I could sell my Orion Concept 97-2 and keep my setup a little less complex.


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## LS-N-IT (Mar 5, 2008)

Download the manual and read the chart that shows which crossovers you can use for the A section, the B section, and the output section and be sure it works for you. (Read closely) 
In my application, the crossovers were not able to bandpass the correct frequencies when bridged (even using the output crossover from another X4R). So I am going to use the amps with a 3sixty.2


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## MaXaZoR (Apr 1, 2007)

How would you bypass the internal crossovers and using external ones from say a Head Unit or external processor (3sixty.2)


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## t3sn4f2 (Jan 3, 2007)

MaXaZoR said:


> How would you bypass the internal crossovers and using external ones from say a Head Unit or external processor (3sixty.2)


Set them the "TH" (through?)


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## lithium (Oct 29, 2008)

LS-N-IT said:


> I was just thinking about using these amps as well.. (I have the KAC-X10 to 1-12" dvc sub right now and it gets pretty ridiculous). Im glad to see a good comparison with other good amps..
> 
> Eventually I may want to try 3 single 4-ohm subs on the X1R (Im starting with two of the CSS SD12s btw), have you tried running it to 1.33 ohms to see if it handles it?
> 
> I did see one note somewhere on the web the X1R kept blowing fuses at 1 ohm, but I would venture to guess they had gains at max and had it in full clipping and then some..


i ran my x10d at 1.33ohms and would assume the x1r would not have a problem. subs where 3 kicker comp 12s sealed and the x10d was tomuch power for them. now im running a AA arsenal at 2ohm. 


to the op, thanks for the review


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## blamus (Mar 9, 2009)

Just a quick question, I'm planning to get the X4R for my front stage 2 way active, and a planetaudio BB150.4 and bridge it to get 600W for the sub. (with the flexibility to go 3way with just these 2 amps in the future)

Now as I was looking at the manual:

1. It says you CAN HP @ 30-250Hz and LP @ 30-5kHz on channel B, i.e. you can band pass above the 60Hz from the infrasonic filter. But you say you can't. Can we clarify this please? 

2. On every site it says its signal to noise ratio is 78dB, which is quite low? Please correct me if I'm wrong but S/N ratio is very important for amps no? But then when I look at the specs on the manual, it says 105db...... so what is it really?

I'm not planning to get the X1R anymore once I found the planet audio. Power wise looks the same, the planet audio is 50% cheaper, and more flexible. Have I missed any advantages for getting the X1R other than the matching looks?


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## tyroneshoes (Mar 21, 2006)

blamus said:


> Just a quick question, I'm planning to get the X4R for my front stage 2 way active, and a planetaudio BB150.4 and bridge it to get 600W for the sub. (with the flexibility to go 3way with just these 2 amps in the future)
> 
> Now as I was looking at the manual:
> 
> ...


1. You can only use either the highpass or the lowpass. Both go from 30-5k. Only way to bandpass is use the infrasonic filter and lowpass but 60 hz is too low for my setup.

2. Different ratings at different levels of output. For all practical purposes, its 105db.

3. Only advantage is more efficiency and smaller size as the planet audio isnt really class d although stated as a "digital amplifier". The PA is a good price so if it does what you want, then go ahead. You can use the line out on the x4r on the pa to add a channel of peq.


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## blamus (Mar 9, 2009)

Ahha, thx for clearing that up for me. 

Where can I find efficiency data for the planet Audio btw? I don't think I've seen its efficiency rated anywhere. But I find it hard to believe its not a class D, or any less efficient than the average class D - simply by looking at the fuses, the size (pretty much the same as the kenwood?), and the reported operating temperature (not hot) - for its power.

But anyway this is a kenwood review, so I'll stay on track and ask one final thing 



tyroneshoes said:


> You can use the line out on the x4r on the pa to add a channel of peq.


How flexible is the lineout? Again, from reading the X and O on the manual (God!) it looks like you can use both the HP and the LP? or maybe not at the same time? And I wonder, if the kenwood works as a line driver (lineout voltage?) if I use the lineout on it instead of the lineout straight from the HU.


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## tyroneshoes (Mar 21, 2006)

blamus said:


> Ahha, thx for clearing that up for me.
> 
> Where can I find efficiency data for the planet Audio btw? I don't think I've seen its efficiency rated anywhere. But I find it hard to believe its not a class D, or any less efficient than the average class D - simply by looking at the fuses, the size (pretty much the same as the kenwood?), and the reported operating temperature (not hot) - for its power.
> 
> ...


The efficiency isnt listed but PA states their mono amps are class d, and do not say the 4 channel amps are class d or a/b. They just call them digital. So if theyre class a/b, efficiency will be much worse.

BB175.4B - Powered By Kayako eSupport 

I actually never used the line out but you pretty much have all the settings of channel 3/4 on it. So you can either high pass or lowpass or bandpass unsing the infrasonic filter and have peq.

I dont think its a line driver, Im not sure, I know it adds some peq but If you have a sublevel on your deck, you would probably prefer to use that.


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## newtitan (Mar 7, 2005)

quick question, as im not sure from the previos posts and reading the manual

a) can I bandpass if I bridge the amp, say 60hz to 400hz? @ 300x2w rms thats is stated in the manual

b) the line out, can you bandpass or ONLY HP OR LP, one at a time?


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## VP Electricity (Apr 11, 2009)

Thanks for the review. Any more info or feedback on the tuning process? The amps must be accessible to tune, correct?


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## tyroneshoes (Mar 21, 2006)

newtitan said:


> quick question, as im not sure from the previos posts and reading the manual
> 
> a) can I bandpass if I bridge the amp, say 60hz to 400hz? @ 300x2w rms thats is stated in the manual
> 
> b) the line out, can you bandpass or ONLY HP OR LP, one at a time?


Channels a and b can only highpass and has no infrasonic filter

channels c and d can bandpass using the infrasonic filter and the lowpass 60hz to 500hz.

It wont work bridged in that setup.

The line out you can only highpass or lowpass and have eq/delay.


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## tyroneshoes (Mar 21, 2006)

VP Electricity said:


> Thanks for the review. Any more info or feedback on the tuning process? The amps must be accessible to tune, correct?


Yeah, you just use the click wheel on the amp and the digital readout also on the amp. Its very easy to set and use. Just be aware of the limitations. Its best for a 2 way active setup or a passive crossover setup and a sub.


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## pylda (Mar 13, 2009)

Any problem with mounting this amp vertically on the back wall of an F150?


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## VP Electricity (Apr 11, 2009)

I am on the phone with Kenwood "tech support" and they don't know squat about their own products... depressing. 

Can't say if the XR4 inputs are differential. Can't say if the XR4S (2009 replacement for XR4) will have DSP still... It's like talking to an 18-year-old at the gap factory outlet store waring a headset in order to talk to a grownup...

EDIT: Per Kenwood, 2009 model with "S" at the end does NOT have DSP, so if you want these, get them now...


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## capnxtreme (Feb 5, 2008)

I have one on the way, so I'll be able to test for sure, but I have heard from a couple sources that the inputs are NOT differential.


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## blamus (Mar 9, 2009)

can someone please explain the significance of 'differential inputs', 'leveled inputs' etc. I have tried looking it up but don't really understand it


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## VP Electricity (Apr 11, 2009)

balanced differential refers to a technique used to prevent inducted noise from being audible. 

Inducted noise in this case is noise picked up by the signal cable on its way from the source unit to the amplifier. It cannot be "filtered out". The cable can act as an antenna, picking up electromagnetic signals which may occur within the audible range. 

Balanced differential signals start with 2 identical signals. One is inverted, so the two signals are mirror images. They are then routed from the source to the destination. If any noise is picked up, ideally the two signal legs - the (+) and the (-) - pick up identical noise on top of their mirror-opposite signals. 

At their destination, one of the signals is re-inverted. At this moment the signals are identical and the noise component is opposite. Then the two signals are re-summed together, and the noise from one cancels out the noise from the other - and you get signal only. 

Balanced differential inputs on RCA amps I had thought were balanced compatible, but shunting half the signal to ground. I had not paid close attention to the differences in these circuits. If I understand what Chad is saying correctly on another thread, the JL amps, and some others (I assume the Arc is like this) is taking the outer shield leg of the RCA input connector, inverting it (which has no effect if it's 0V DC ground), and then adding that signal to the (+) leg connected to the inner pin. 

If the pin is grounded in a traditional common-ground single-ended RCA circuit, nothing bad happens. If the RCA is connected to a true balanced signal, you still get the benefits of balanced, in a two-pin configuration. Also, balanced inputs can take floating-ground speaker-level signals as long as the input sensitivity range is great enough.


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## VP Electricity (Apr 11, 2009)

balanced differential refers to a technique used to prevent inducted noise from being audible. 

Inducted noise in this case is noise picked up by the signal cable on its way from the source unit to the amplifier. It cannot be "filtered out". The cable can act as an antenna, picking up electromagnetic signals which may occur within the audible range. 

Balanced differential signals start with 2 identical signals. One is inverted, so the two signals are mirror images. They are then routed from the source to the destination. If any noise is picked up, ideally the two signal legs - the (+) and the (-) - pick up identical noise on top of their mirror-opposite signals. 

At their destination, one of the signals is re-inverted. At this moment the signals are identical and the noise component is opposite. Then the two signals are re-summed together, and the noise from one cancels out the noise from the other - and you get signal only. 

Balanced differential inputs on RCA amps I had thought were balanced compatible, but shunting half the signal to ground. I had not paid close attention to the differences in these circuits. If I understand what Chad is saying correctly on another thread, the JL amps, and some others (I assume the Arc is like this) is taking the outer shield leg of the RCA input connector, inverting it (which has no effect if it's 0V DC ground), and then adding that signal to the (+) leg connected to the inner pin. 

If the pin is grounded in a traditional common-ground single-ended RCA circuit, nothing bad happens. If the RCA is connected to a true balanced signal, you still get the benefits of balanced, in a two-pin configuration. Also, balanced inputs can take floating-ground speaker-level signals as long as the input sensitivity range is great enough.


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## blamus (Mar 9, 2009)

hmmm. i think I get half of that 

So, the fact that the kenwood amps' inputs are non-differential or unbalanced, does that simply mean that they are more susceptible to noise picked up from poorly shielded cables? Or are there other implications? For example, source/HU compatibility etc?

Are non-differential or unbalanced inputs in car audio amps a big nono or is it common? I.e. should it make a practice difference for me? Should I worry about it?


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## VP Electricity (Apr 11, 2009)

I think you might want to go over to the balanced input thread, but basically, if you have a HU with RCAs and an amp with RCAs, you are compatible regardless.


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## tyroneshoes (Mar 21, 2006)

Just an IME. I was using a rf 360 and pdx amps and had noise issues previously. Replaced them with these and the noise was gone. 

I dont have any noise issues with the kenwoods.



pylda said:


> Any problem with mounting this amp vertically on the back wall of an F150?


I wouldnt think so. Theyre also fan cooled.


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## VP Electricity (Apr 11, 2009)

Apparently these are already disco and the replacement "S" witthout DSP is already shipping. Looks like KW didn't communicate what was cool about these. 

I got a line on 5 units on displays I can get for a good deal - if anyone is interested I can look into it more...


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## blamus (Mar 9, 2009)

well i'm about to get one, and the cheapest i can find is refurb for $180 or something...


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## Xtreme03 (May 27, 2006)

I don't understand why any manufacturer would remove a good feature, like DSP. You would think they would be continuously improving their product, instead of taking a step back. That's what their lower end amps are for. How lame...


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## lithium (Oct 29, 2008)

pylda said:


> Any problem with mounting this amp vertically on the back wall of an F150?


i got my x10d upside down on my rear deck since winter, now that its getting warmer ill watch to make sure its ok but its never ran too warm even after 3hour+ drives.


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## Babs (Jul 6, 2007)

Xtreme03 said:


> I don't understand why any manufacturer would remove a good feature, like DSP. You would think they would be continuously improving their product, instead of taking a step back. That's what their lower end amps are for. How lame...


Didn't sell. Only amp I've seen anywhere near it's pricepoint with such processing.. Didn't catch on unfortunately.

On the X4R's inputs.. I asked Kenwood long ago and got reply they certainly are not differential inputs, just regular RCA.

On non-differential being a no-no... Actually it's much the norm that amp inputs are not differential-balanced. It's the exception to have such a feature.. Not many aftermarket sources apparently feed balanced outs, so they didn't see the usefulness. HOWEVER, for long line runs, balanced is very cool.. One reason Audiocontrol units like to use it.. noise-cancellation when the opposing phase signal is swapped and combined (summed) with the other. There are however, quite a few amps that do have differential in's, JL being the most widely known, then Rockford and apparently the PDX's.. Even some Kicker.. Don't know about Eclipse or other.

Only reason I know this large amount of useless information.. My Si OEM head unit puts out balanced 4-ch flat signals to the OEM amp.. Tapping into those signals to processor/amp with balanced in's would be a cool integration setup. Reason I hoped the X4R was balanced.. Simple 1-box solution.

I wonder though about the 3sixty.2.. I've heard horror stories feeding it balanced signals.. ie. from BMW or Acura OEM heads pre-oem-amp.. I'd love to know for sure though if it would work for a decent oem processor.


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## slowgoer (Feb 16, 2009)

any good price leads before they are gone and i can only get the "S"?


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## Silver2003srt4 (Jan 3, 2009)

Nice I like the look, I would like ot hear how one sounds
Jeremy


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