General Car Audio FAQs

I don't even know whether the factory HU from my 2nd gen has preamp outputs, and it's sitting on a shelf in my garage since I pulled it out years ago.

I'd guess that if there's no factory amp then the factory HU probably doesn't have a preamp output.

Most sources will generally recommend replacing the head unit as a higher priority than upgrading the speakers to improve your sound over the factory system, but I've got no idea how expensive that is for 2-DIN systems with built in nav.

I replaced the factory 2-DIN box (which was having some issues) with a single DIN head unit and an in-dash CB unit and when I want GPS nav, I either just use my phone or the 10 year old Garmin hiking unit that I have a RAM mount for on my A-pillar. One of these days I'll try to get around to upgrading the speakers and maybe adding a power amp/sub to the mix.

 

The factory headunit does not have low level outputs however that amp has speaker level input capability so you don’t “need” an aftermarket headunit in that aspect. You are however limited in tuning capabilities with a factory headunit so if you are looking to get the “most” out of your system an aftermarket headunit (or an external dsp) will allow you more tuning capabilities.

 

Thanks for the responses. Additionally, can you chime in on if it makes more sense to: run the speakers @75 RMS each + the sub @ 250 RMS OR the speakers @100 RMS each + the sub @ 350 RMS. I get confused with the ohm load difference between these two options. The speakers don't support more than 80 RMS each and it's with using an Alpine PDR v75 and a 10" JL audio W3.

Thanks!

 

If the speakers are rated at 80W RMS, then running them at 100 is asking for trouble (or bad sound due to clipping at the very least). Personally, I'd probably use speakers rated at 100W or more on a 75W RMS amp but that might be an abundance of caution on my part since 80W speakers on a 75W circuit should be OK.

If you've already selected the speakers, then altering the impedance would be difficult to accomplish. The specs on that amp mean that if you use 4 Ohm speakers (in my experience, most car speakers are 4 Ohm but you should check what you're using) then it'll drive the 4 channels at 75W each, and if you use 2 Ohm speakers (or pairs of 4 Ohm speakers wired in parallel, which is hard to really do in a car install) then it'll drive at 100W. Same goes for the subwoofer circuit, but I don't know for sure that it'd potentially be safe to use a 2 Ohm subwoofer load with 4 Ohm loads on the mains since that might depend on the internal architecture of the amplifier.

If you have 2 Ohm speakers, it's theoretically possible to increase the circuit impedance by putting an additional 2 Ohm power resistor in series with the speaker, but I've personally never had any success with doing that so I wouldn't recommend trying.

 

I will not be installing the system so I'm pretty confused once you start talking about the ohm loads.

The fronts are a component set that handle up to 80 watts RMS @ 4 ohms
The rears handle 50 watts RMS and Crutchfield doesn't list the ohms
The sub handles 100-400 watts RMS @ 2 ohms or 8 ohms
The amp lists it can run :

• 75 watts RMS x 4 + 250 watts RMS x 1 at 4 ohms
• 100 watts RMS x 4 + 350 watts RMS x 1 at 2 ohms
• 200 watts RMS x 2 bridged at 4 ohms + 350 watts RMS x 1 at 2 ohms

The shop said this exactly, "You can get a 5ch amp to do everything. I have a Alpine PDR-V75 that would give you 100 watts per ch to the door speakers and 350 watts to a sub."

 

That amp will definitely do everything you need for a 4 channel + subwoofer setup, the problem is that your speaker selection isn't entirely suitable for the amp.

If you're going to run 50W speakers on a 75W or 100W amp channel, you'll want to set the Fader heavily to the front, or have the installer turn down the gain on the amp channels going to those speakers (if the amp has gain adjustment for individual channels). That amp would be able to blow those speakers without having the volume up all that high on the head unit if you're not careful. The fronts should be OK, but I wouldn't recommend running at high volume levels frequently or for long with that setup; if it's possible for you to do at this point you should get a different pair of speakers for the rears; overdriven speakers are going to sound like fried hell before they blow entirely, and then they'll sound worse than that.

If you're having a shop do the install, you might want to give them the make/model numbers of all the gear you're using and ask if they see any compatibility issues since they'll likely know where to get specs and how to read them (ask the installer, not the sales staff if possible). If you're paying them for their skills and knowledge in an area that you're not comfortable then you should take advantage of that knowledge to help you choose appropriate components for the system you're looking to set up.

 

I've actually already sent them the list of speakers I have prior to purchase and he said it's fine. What I'm wondering about now is why he states they will be set up to run each speakers at 100 watts. Because as you say this can be an issue, I'm having doubts about the person installing them now. I can easily return the rear speakers to Crutchfield if necessary.

EDIT: I just emailed him and told him bmgreene says you don't know what you're talking about just kidding, I asked if either of those amp output setups will efficiently power the speaker setup I currently have.

 

Whether the amp is running 75 watts or 100 watts depends on the impedance level of the speakers that are connected, I don't think it's a setting on the amp itself.

It's possible that they're already planning to turn down the amp gain on the 50W channels. Looking at the manual for the amp, there are separate crossover and gain setting for channels 1/2 and channels 3/4, so they could dial down the gain so that the 50W speakers aren't being overdriven (you'll probably have a hard time hearing them over the fronts since they'll be quieter and farther away) and they might also set the crossover a little higher to send the low end (which makes up the bulk of the power in any speaker) to the subwoofer, but you also don't want the sub trying to make frequencies that are too high or it's going to sound weird.

If returning the 50W speakers and getting something in the 80-100W RMS range is an option, I'd recommend that since it'll give you a more balanced sounding system that'll be less likely to accidentally break something.

 

I know you're joking with this, but I do want to clarify that my knowledge is limited to personal experience (and a bit of electronics knowledge left over from engineering school). If you're going through a reputable shop, I'm sure the installer knows what they're doing (sales staff can be hit and miss with real knowledge about the tech side of things even at a reputable dealer), but there are definitely ways that they can make things work together even if a slight tweak to the components would allow for a much better sounding end result.

Another aspect of using the lower-power speakers is that there's always a danger of you coming along later and undoing something they did for a reason you don't understand. The main example would be if you decide you don't like the lower volume coming from the rear and have someone who doesn't know those speakers are weak either adjusting up the gain on those channels or showing you how to do it yourself, which could then lead to blowing the speakers (which might then also lead to damaging the amp itself). If the speakers are all robust enough to take the full amplifier output without damage, there's not nearly as much danger of the system eating itself if it's pushed too hard.

 

For sure and I appreciate the advice. I just sent out an email to them for clarification on how this will all be set-up so I understand it as well; it's the only way to learn for myself.. ya know? I may end up exchanging out the rear speakers for something that can handle more wattage though. The fronts can handle 80 RMS, so if they hook the amp up to send 75 RMS it seems closer compatibility wise on paper.

Still unsure if I should get an aftermarket head unit.

 

When I've picked out components for systems with a power amp and sub, I've generally used speakers that are rated for RMS wattage about equal to the peak wattage on the amps, but that's probably a real abundance of caution on my part. As long as the RMS rating on the speakers is any amount above the rating on the amp it shouldn't be possible to over-drive the speakers at max volume.

I've got a habit of over-building almost everything when left to my own devices. I went the DIY route when I wanted to get my home system speakers a bit up off the floor (mostly I just couldn't find any commercial stands in the height that I wanted); now I have what's possibly the world's only pair of 8" tall solid cherry speaker stands.

If you've got the money and can find a unit you like I'd definitely recommend an aftermarket HU. Running off pre-amp outputs makes it easier to use coaxial or shielded cables for the connection, which makes it a lot harder for the system to pick up rf or electromagnetic interference off the engine (ignition coils in particular make a lot of noise), and might make the installer's job a bit easier as well since they might not have to tap into the factory harness except to maybe connect a steering wheel control adapter (I think those cost around $30-50, but it's been a while since I bought one).

 

My apologies if this is redundant as I did not read all of the long posts I saw below!
The load the amp “sees” is dependent on the resistance of the speakers/sub and not “user adjustable”. Since “you” have control of the volume knob the speakers will not “see” 100 watts unless “you” turn it up to that point. In any case I typically run more power than my speakers are rated for (my current speakers are rated 60 watts rms and my amp puts out 100 watts rms) to have a little headroom so the amp doesn’t “crap out” during heavy peaks in certain music and as long as you are careful with the volume knob you will be fine with 100 watts on 80 watt speakers by following this advice...if it sounds distressed it is distressed so turn it down before you blow something up!

BTW, I don’t have time to get on forums much these days but feel free to call me at the number below my screen name if you need any help.

 

Awesome, thanks for the replies on my questions. They have definitely helped me understand audio a lot more.

 

Does anyone have a wiring layout or diagram or ANY INFORMATION AT ALL about the head unit in a Gen 3 Tacoma 2020? I have found no information whatsoever about what the wiring situation is or what the back of the head unit looks like. ********* generally sucks as far as information is concerned and I bought from them in the past - received something that did not work and they would not refund. Live and learn.

I am really annoyed that there does not seem to be ANY wiring diagrams or technical information ANYWHERE about ANYTHING with this truck. I just bought it and I am really disturbed about the dearth of detailed information about everything regarding the vehicle.

 

If it makes you feel better, this is the case for nearly every vehicle made. It takes several years for lots of info to start coming out and enough people have messed around with them and posted pictures. Manufacturers have zero reason whatsoever to post any info about wiring or any other detailed information for that matter.

there are some threads on here where people have posted pictures and diagrams for the 2020. Do some digging and you’ll find them. Not sure of the thread titles off the top of my head

 

Hello, just bought my first ever 2021 TRD Off Road with the JBL speakers and radio. I have been searching the forums for the last two days looking for any guidance about upgrading the stock sub and I haven't had much success at seeing how people are upgrading their systems. I saw the thread with all the sub set ups and that's awesome, but my question is there a guide about adding a JL Fix 86 or an LC7 or something like that to get a strong signal to aftermarket subs? I wanna keep the headunit and don't mind the stock speakers, i really just want to improve the bass a bit. Anyone point me in the right direction or done a build like that already and can share?

 

It is very easy to upgrade the sub in a Jbl system with no need for an external processor. Just get a mono amp that accepts high level inputs and connect to the outputs of the JBL amp to the sub. I’d also recommend an amp with a remote level knob so you can control the sub volume separately.

 

I am also doing same. Use a adapter to speaker wires to RCA? What wires go where?

 

Don’t get too anxious if nobody replies, Man. Last response is a little old.

Big Welcome to TW.

 

Thanks. No problem. Im researching on here insteak of a new old post haha figured its beeen answwerd befo bit kt finding yet