What are the xover freq. for the stock speakers in a 2001 Dbl Cab TRD ?

I've searched around for quite a while but can't find the answer. What are the stock speaker specifications? In particular, the crossover frequencies? My stock head unit blew and I replaced it with an affordable JVC unit that does have settings for the crossover frequencies. I can also turn it off altogether I believe. Thought I might be able to clean up the sound a little bit or at least set the new HU to do some filtering and save the inline passive filters from doing any more work than need be. Without tearing things apart, I believe I have passive tweeters and no sub. My unit does NOT say JBL on it, so I think it was one of the lower-end audio systems, which did surprise me. Anyway,,,,,, help is appreciated.

2001 Double Cab, V6 TRD

 

i had done the math on my other vehicle with a very similar setup quite a while ago. the tweeters were set up to come in around something ultra high like 12khz or so.

the main issue with the tweeters is the voltage of the capacitor. changing to a higher voltage capacitor with the same uF would offer a boost in usability with most aftermarket units, but is just as much of a hassle as changing them out to any other model that does that already with better lasting components.

otherwise, if you don't have any other modifications to the system, the oem radio just ran full-range to the speakers, and let the tweeters figure themselves out. i typically choose to run a 40-60hz high pass on stock speakers to protect them from me. it offers a little more volume for the drive home, at the consequence of less bass.

 

That is awful high. It's typically around 3-3.5kHz. I doubt the mids in the doors are playing that 3.5-12kHz range very well if at all. I'm probably missing on a lot of sound if it really is 12kHz.

I think what I'll do is simply "listen" to my system (maybe with a stethoscope) while playing with the HU xover settings and I may be able to hear where those tweeter crossovers are at. I'll do the same for the door speakers. Manufacturers typically use around 70Hz for the lower cut off on those so your math seems close on that one.

I imagine the new HU does put out more power than the original stock radio, so I can see the concern in blowing the tweeters. I'll cross that path when it happens.

Thanks for the response.

 

i've got a 2018, but i believe the tweeters are the same. toyota doesn't change much very often. but the difference in frequency response is dealing with oem factory and aftermarket.

this is my tweeter, only mounted in the dash instead of the door, but the same configuration tweeter/woofer setup


i gutted the rear of my tweeters to use as a splice point to power up my door woofers temporarily-permanent, but the pictures have enough detail




in the second picture, i can make out the specifications, which would be what they would've calculated the crossover off of. in the first picture, i can make out that the capacitor used is 2.2uF, @25v (25v is really the part that causes distortion within the design--needs to be at least a 50-100v)

according to this calculator, a 4ohm load would result in the crossover slopes -3db end will be at 18khz.
though, many 4 ohm speakers will measure closer to 3 ohms(like 2x4 lumber is 1.5x3.5), which means that the crossover will end at 24khz.

but that's assuming a tight binning specification on the capacitors. typical binning is 5-10%, meaning the capacitance range within 10% of the target capacitance is acceptable. if we assume 10% binning, that means each 2.2uF capacitor could be anywhere from 1.98uF to 2.42uF. making a possible 4ohm frequency response end point anywhere within 16khz-20khz. with the 3ohm load, that changes to 22khz-27khz. this also doesn't factor in the resonant frequency resistance change, or the end-circuit resistance of the complete circuit, either of which could drastically increase the load the capacitor acts on, which could drastically drop the crossover frequency.

that said, we're also only dealing with a 6db/oct crossover
entering those specifications here, we can see a rough approximation of the response curve
https://speakerwizard.co.uk/calcs/Crossover_Calc_v2.php

-6db response is at 10khz,
-9db response is at 7khz
-12db response is at 5khz

typically, conversation on frequency response/crossover slope stops at -6db most times, with individual output balancing being discussed entirely separately, but i note the -12db response because i'm theorizing the original toyota sound engineers possibly worked to accomplish two goals with a single component design. they're likely controlling the frequency to the speaker, but also controlling the brightness of the speaker, while using the natural roll-off of the oem radio amp chip, and the natural paper cone to control the speaker from sounding too 'bright' at the higher frequencies.


for fun, these are the dash speakers out of my 2014 subaru/toyota brz,which are also wired similarly. difference being that the dash contained 2 pairs of speakers, each with their own crossover.



the tweeter states 4ohm, with a 2.7uF/50v capacitor
the midwoofer measures at about 3.5 ohms(4ohm), with a 10uF/100v capacitor.

the tweeter calculates to 14.5khz @4ohms
the midwoofer calculates to 3.8khz @4ohms

factory speakers just run far higher than one would typically expect, i suspect it's a physical compensation for the low-cost BOM. which is actually really interesting to me how they made do with so much less, which is really the whole point of this deep dive--not at all to correct you, only to document my effort to sate my own curiosity.

 

Soundman, that was some good stuff. I have a degree in Electronics Engineering but it's been awhile since I dealt with analog circuitry. I had to go refresh myself with a few things. I actually built a FM radio one time and had to design a tuning circuit to tune in one of the local radio stations to pass a class. Fun stuff. You don't happen to have an idea on the door speakers frequency range and slope do you? It would be real cool to see the charts on these old speakers. Maybe I can pipe in on the 1st gen thread to see if anyone can get me the model numbers of the speakers. Maybe I can find them. Offhand, I say set the high-pass filter higher than expected to start, maybe 5kHz and work it up from there until it becomes crisp and clear without dropping any sound. Then play with the low-pass filter and do the same. Without knowing the specs on the door speakers, I can't begin to guess how high I can set it without losing that range of sound from the low-end of the tweeters to the top-end of the mids. I thought I read somewhere that some Toyotas have JBL stamped right on their HU. Mine did not, but maybe it was still designed by JBL along with the speakers.

 

this is what i get for being speaker-obsessed i'm not officially trained on any of this. much of it comes from grabbing everything i could from every source i could locate, and then trying things out on trash-bin-revived speaker parts...


on all the vehicles i've fussed with(i used to also frequent junk yards and pull the more premium offerings out of many different models for my own desires), they all have a high pass on the tweeters, and then nothing on the woofers-- the tongue-in-cheek term for that would be 'acoustic filtering'...

all of it comes down to the cost and warranty period. a tweeter without a high pass won't last very long from the bass overheating the voice coil, where an 8khz signal can easily go through a woofer without damage, it just can't reproduce it effectively because of the physical mass of the assembly.

put another way-- the audio signal is effectively a PWM signal. i can easily run a 130v light bulb on 220v if i modulate the PWM rate to it, which is essentially what high frequencies do to woofers.

being that heat and the lack of it's dissipation is ultimately the killer of any speaker--heat eventually breaks down the voice coil, either electrically burning up the copper in tweeters where movement is limited, or where woofers typically fail most often physically is by softening the glue's in the voice coil windings until it de-laminates and the now-loose coil rubs within the magnetic gap and breaks the conductor.

a woofer of any design has a larger motor structure, which means a larger thermal dissipation modes, which means that even though the 8khz example frequency might not be physically reproduceable, the thermal load it creates is far below the limitations of the woofer-- so it absorbs and dissipates the thermal load.

conversely, smaller speakers like tweeters, due to their smaller motor structure mean they have less thermal overhead, and the lower the frequency, the larger the constant voltage(the lower the PWM frequency), meaning there's more thermal load imposed on the motor structure that can't be utilized. with less space, there's less dissipation, which allows for a faster thermal runaway condition--but it's still not all that 'fast'. i've ran '1Watt' speakers full range on 75watts for up to 10 minutes until they fail.


and as far as the JBL stuff
https://www.theautopian.com/the-open-secret-behind-most-premium-car-audio-systems/

none of the non-branded stuff is going to say much-- you can see in my pictures of the speakers i already posted, they don't have any official branding on them. it's odd to even have a speaker with wattage, or ohm labels on it like the tweeters. i've got a few 8" ford subwoofers that were offered in different packages. 2 are fully stickered with specs, the other two are un-labeled, but they're all identical in build, right down to the mold lines. much of the bose stuff only contains the bose name and the part number, and most jbl stuff really only includes the jbl name on the back.