Hello all. I'm visiting from Range Rover forums. I'm doing an experiment with a stock amp that came from a 2011 XJ that I have installed in my 2016 Rand Rover Sport that has a miserable base 8 speaker system that sounds like 20 watts per channel to me. After researching the Range Rover forums and channel on YouTube, I see that upgraded amps are somewhat interchangeable between some of the Land Rovers and Jaguars. He listed some tested amplifiers that worked with both brands but the amp I have is not one that was tested in their experiment, but looks identical. To make a long story short, the amp I have works. But I would like to know about the specs of the original system. I was hoping someone could run the VIN or the engineering number of the amp to tell me what it was originally rated for, how many speakers the XJ had connected and configuration, or even better, if you know how many watts per channel this amp is supposed to be putting out. I would like to get the best match for replacement door speakers. Here's the info I have for the car it came from:

2011 Jaguar XJ, VIN: SAJWA1CB4BLV14351
Amp Eng#: AW93-19C164-AR

This amp did come with both connectors for mid range and subwoofer and surround speakers but I'm not sure what speakers were connected originally. The label on the amp says "High 12" which is believed to be a 600 watt, 12 speaker system but this is not always the case. Additionally, the subwoofer output is the main piece of information that I need. I have a stock, under passenger seat, dual coil subwoofer that came in high line spec Land Rovers and has two 2 ohm coils. Not sure if this amp is looking for two 4 ohm or 2 ohm coils/speakers. With my sub connected, it's very low output but door speakers get plenty of power.

I know it's a long shot, but if anyone has gone down this path of stereo upgrades, your input would be greatly appreciated.

 

shaundh, I have done my fair share of stereo work. I am not finding anything that says what the specific power outputs are for each channel. So, I am going to make an educated guess based on what my experience with building stereos and also my numerous years of working in the electronics field.

Based on what you are saying, you have the 600 watt amplifier. So, that would be 600 watts peak. If it was 600 watts RMS, it would specify RMS in the power rating. With this being said, 600 watts peak based on modern day power ratings for amps, you are looking at about 300 watts RMS. Yes, in theory 1 watt RMS is equal to 1.414 watts peak, but manufacturers love to play with the numbers ot make their amps appear bigger than they really are and I find a 2:1 relationship is closer to reality. So, your 12 channel amp, if all was divided equally (more on this in a minute), would leave you with 50 watts peak/25 watts RMS for each channel. But, because you have 2 channels reserved for subwoofers, those are going ot need a lot more power than the other channels. I am guessing that they are going to be around 100 watts peak/50 watts RMS each. So, this is going to leave you 400 watts for the remaining 10 channels, or 40 watts peak/20 watts RMS. I could be wrong here as most amps are rated based on 4 ohm speakers being used on each of the outputs. But, some amps are designed to handle a lower resistance speaker and not get damaged which will normally allow for more power output. But, I doubt this is the case as the manufacturers want the highest number that they can get to make things seem bigger and you are getting more for your money. So, if Jaguar/LR is saying it is a 600 watt amp, it is maxed out at 600 watts peak.

Now, for the actual design of the system. Each front door is getting 120 watts peak total that is being split between 3 speakers (each getting 40 watts peak). The rear is getting 80 watts peak to each door (2 speakers each getting 40 watts). So, for the front doors, you have a tweeter, a mid range, and a mid-sub speaker for your 3 speakers. The rear doors get a tweeter and mid range speaker. So, the tweeter is going to only output 40 watts peak for the sounds at/above 3000 hz (something in that range). the mid range is going to output 40 watts peak for sounds between 600 hz and 3000 hz. Then your mid-sub speaker is going to cover say 200-600 hz at 40 watts peak. So, in reality, for the 200 Hz to 20K Hz range, you are only ever putting out 40 watts peak at most. The same is true for the rear where the tweeter is going to cover the 3000+ Hz range at 40 watts peak and the mid range is going to cover the 200 Hz to 3000 Hz range. You then have your subs running from 200 Hz on down at 100 watts peak each. This would give you a fairly well rounded sound. Reading your post, there is some confusion as to whether the subs are running at 1 ohm or 4 ohm (due to being dual 2 ohm speakers). The best advice I can tell you is to put a multimeter on a speaker. A 1 ohm sub is going to read about 0.9 ohms and a 4 ohm speakers is going ot be around 3.6 to 3.8 ohms. If you are running 4 ohm subs and you find them to be very quiet, then it is very possible that the factory amps are running at 1 ohm load. None of the information I have says what the speakers are rated for.

the frequencies that I call out are my best guesses. Depending on the maker of the speaker, they may have different "recommended numbers" for the min/max frequencies of a speaker. But, based on the speakers in my car, these numbers are going to be fairly close to what is actually happening. If you are into car stereo and understand the terms, then this will make a lot more sense for me to say that the amplifier is really an active 12 channel crossover with static amplifier outputs. Personally, for ease, I would have done a 5 channel setup using passive crossovers for the front and rear doors using a 1 inch tweeter and a 5-1/4" speaker. then use a quality 10 inch infinite baffle sub for the low range. Get the same sound, fewer components and a lot more volume for the given power. But, that would only be 9 speakers on 5 channels, not 12 speakers on 12 channels. gotta love marketing.

If you have more questions, please let me know. I will see what I can find and go from there.

 

Awesome info man! Thank you so much. I have an electronics background as well (although rusty) so I can follow you for the most part. All I know is I can get output from each of the pairs of wires from the amp that goes to the sub when I connect one of my uninstalled mid speakers to said channels. But when I connect it to the installed underseat sub, I can't tell if it's working at all. The sub has 4 wires, a pair for right and left channel sw1 and sw2 positive and negative. Each pair measures approximately 2 ohms. I need to make sure the sub is not defective - I just assumed it would work since I got the correct ohm ratings. Either way, I'll post back my findings.

 

shaundh, if you are wiring the new amp to the DVC sub, make sure that the polarity is correct on the 2 voice coils. If you wire one of the voice coils backwards (ie, amp positive to the negative terminal of the speaker and vice versa), but you have the other wired correctly (amp positive to speaker positive), the 2 signals will be opposite of each other inside the speaker and that will result in low volume from the speaker. In short, as 1 side of the amp tries to push the speaker out, it will push the speaker out, but the second side is going ot be attempting to also push the speaker out, but because it is wired backwards, it will be pushing in. So, your 2 voice coils are going to be fighting each other due to one pushing and one pulling, cancelling each other out. I would start there if you are having a low volume out of the sub.

 

Thank you so much for the tip. Good news. I got everything working! I found that the pinouts to the sub were wrong. I purchased a factory underseat sub but it did not come with the other connector from the wiring harness. So I had to purchase a separate WPT688 connector. This connector just had black wires and was numbered 1 thru 4 but the numbering did not match the subs numbering, I guess. This was key because the colors of the wires coming from the subwoofer are different from the wires coming from the wiring harness to the amp. So I found the attached picture and this helped me figure out what was wrong and how to wire it correctly. As soon as I powered it up, the sub was working!

So, your advice was spot on! Thank you. The bass response is so much better and I'm glad I did not have to take up space in the rear with a box. Very clean.
Now I just have to finish installing the door speakers. I've verified that all the other speaker connection work and sound is better already.