Ohm/watt ratings for stock speakers/head unit

[swarb]

I am planning on upgrading the stock speakers(and possibly add an amp) and would like to know how they are wired/powered by stock wiring so I don't overload/underload the factory amp for reasonably balanced sound/power. This is for a 2015 Brz with the factory head unit.

1. Ohms for each specific speaker?
2. How are they wired?
3. Watts each specific channel? (so I can select a speaker with low rms/high sensitivity)
4. How to get a signal for amp? headunit have rca's or should I use line output converter? or find an amp with line level inputs?
5. Are there any crossovers on factory setup?

[cjd]

I don't have answers for any of this specifically without searching (and I know I've read just about all the answers before here so you can find the info) but...

Don't bother trying to match RMS output with power handling. You're more likely to burn out a driver at the max amp output level (even RMS) than you are driving it well below the amp max but at the driver's limit. Distortion destroys (your ears as well as drivers) - most power ratings are thermal limits anyway. It's more complicated than that.

If there's a crossover, it won't work well with anything else (assuming it works well with the stock parts, and my ears tell me otherwise.)

You only have to be sure to stay above the minimum impedance supported by the amp stage - though of course it's wise to stay close because power ratings aren't likely so linear...

good luck.

[wparsons]

Originally Posted by cjd

Don't bother trying to match RMS output with power handling. You're more likely to burn out a driver at the max amp output level (even RMS) than you are driving it well below the amp max but at the driver's limit. Distortion destroys (your ears as well as drivers) - most power ratings are thermal limits anyway. It's more complicated than that.

Not an expert, but don't speakers for higher output need more input?

ie: if they can handle 100w RMS they'll produce less output on 25w RMS than a speaker that can handle 50w RMS?

[babydriver]

Originally Posted by wparsons

Not an expert, but don't speakers for higher output need more input?

ie: if they can handle 100w RMS they'll produce less output on 25w RMS than a speaker that can handle 50w RMS?

Not necessarily. You have to consider the efficiency of the speaker. This is rated in dB at 1 watt input. IOW, how much loudness is present with a 1 watt input? The rating is usually somewhere between 88 dB and 94 dB. Two speakers with the same efficiency will produce exactly the same amount of volume at 25 watts, regardless of what their power handling is. As someone else has said, power handling is almost always a function of how much current the voice coil can absorb without being destroyed.

That's not really the limiting factor, though; distortion is. If your speaker doesn't have a long enough excursion with good control of the cone then more power will simply bottom it out and destroy the voice coil. Long before then, though, the sound will crap out because the cone is no longer traveling in a linear (piston-like) fashion. If a speaker is designed to work best with 15 watts and you drive it with 50, the peaks will be badly distorted and the system will sound bad.

I suspect that the FR-S speakers are high efficiency and the sound system is low power output. Increasing power will probably just overdrive the existing speakers into distortion.

Alas, there is no free (or even cheap) lunch!

Added: Bear in mind also that the majority of the time, the audio signal is probably below 1 watt! Only on the peaks (drum beats, note attacks, etc.) will the power exceed this low level. Of course, it can exceed it by a lot, which is why having more power is a good thing generally. Still, if the speakers don't have enough excursion to handle the extra movement of the cone, any extra power is wasted.

[cjd]

Originally Posted by wparsons

Not an expert, but don't speakers for higher output need more input?

ie: if they can handle 100w RMS they'll produce less output on 25w RMS than a speaker that can handle 50w RMS?

No. That's all about sensitivity, typically rated at 1W - when done well, at 2.83V (which is 1W@8ohm) - if you want louder on less power, look for higher output ratings; know you'll probably give up bass response, and in a cheap driver, power handling.

For example, in the home driver market you may see a driver with thermal limits between 80W and 100W but 89dB@2.83v - a pro driver may be 1000W rated and 96dB@2.83v. Other properties change, however.

The subwoofer setup I have in my home theater has a 700W pro amp on it, but is excursion limited to only ~200W (it'll reach to ~12Hz pretty comfortably.) It's thermally limited to something like 3000W, though I'm not checking my numbers so that may be off.

You choose the parameters you want in the system and build toward it - assuming you're doing that kind of work. But you probably need to understand how this works to be successful that way. I'll be embarking on a fully custom setup soon, probably a bit different than the usual since I do a lot of custom work for home setups and have different priorities...

If you want insane drivers in the door, look no further than the Anarchy... but it's not all that sensitive. They're fun to push HARD, and I haven't destroyed one yet...

C

[babydriver]

Originally Posted by swarb

I am planning on upgrading the stock speakers(and possibly add an amp) and would like to know how they are wired/powered by stock wiring so I don't overload/underload the factory amp for reasonably balanced sound/power. This is for a 2015 Brz with the factory head unit.

1. Ohms for each specific speaker?
2. How are they wired?
3. Watts each specific channel? (so I can select a speaker with low rms/high sensitivity)
4. How to get a signal for amp? headunit have rca's or should I use line output converter? or find an amp with line level inputs?
5. Are there any crossovers on factory setup?

1. The ohm rating is probably 4, but just look at the back of the speaker magnet. It should be provided there. Or, get an ohmmeter and measure it directly across the terminals. Technically, you need to be measuring impedance rather than resistance, but in most cases it will be "close enough for jazz." Standard values are 2, 4, 6 and 8 ohms. It is not a big deal to raise speaker impedance (go from 4 to 8), but you will halve your power output. To go the other way, say from 4 to 2 ohms, you run the risk of frying the output transistors on your amp since they may not be able to handle the additional current.

2. They are wired with each speaker being driven by its own channel amplifier within the sound system and they should be phased the same. (Red+ to red+, black- to black- for all speakers.) No interaction should be occurring if each has its own channel amp.

3. I don't have this information. Sorry.

4. All of these could work; just choose what is best (or easiest) for your setup. I have not had the head unit out of the FR-S dashboard, so I can't say if it has RCA's or not. It is entirely possible that the outputs go directly from the power amps to the speakers, with all connections internal and no access at line level. In that case, you will have to go with speaker level inputs on the amp. Not the best way, though, because any upstream head amp noise (thermal noise, hum) will also be amplified by the downstream power amp.

5. The crossover is probably passive and if so, is tailored to the speaker
itself. You could not use it on a different speaker. Sometimes, it is nothing but a capacitor on the tweeter. Hopefully, there will be some sort of inductor on the mid/woofer at least to limit its bandwidth in addition to the cap on the tweeter.

The good news is that the crossover ought to be attached to the speaker or accessible so a changeout is possible. Make sure the new crossover is tailored to the new speakers.

I strongly suspect that it would be easier to ditch the head unit, but don't know who makes a suitable substitute unit. It's not a great unit, that's for sure.

[babydriver]

I found this link:

http://www.scion.com/BeSpoke/features/

It provides some of the information that the OP wanted.

"Six 2.4-volt pre-amplified RCA outputs for front, rear and sub-speakers, allowing owners to add external amps to boost power and expand the sound field for a truly custom speaker system"

(2.4 volts is the maximum output level that will drive the inputs on the power amp.)

[babydriver]

Actually, I'm not sure what Scion means by "expand the sound field". It will be exactly the same size, dependent on speaker placement. Marketing BS.

[cjd]

Originally Posted by babydriver

Actually, I'm not sure what Scion means by "expand the sound field". It will be exactly the same size, dependent on speaker placement. Marketing BS.

Not necessarily, though exactly what is the baseline which is expanded might be questioned. You can do some funky things with proper phase mixing, and that can be post-processed. Placement is absolutely a part of the equation though.

[swarb]

Originally Posted by cjd

snip*

Don't bother trying to match RMS output with power handling. You're more likely to burn out a driver at the max amp output level (even RMS) than you are driving it well below the amp max but at the driver's limit. Distortion destroys (your ears as well as drivers) - most power ratings are thermal limits anyway. It's more complicated than that.

snipped*

I don't understand what you are trying to explain, can you word it a little more simple? Are you trying to say I am more likely to burn out a driver underpowered than an overpowered driver?

I am mainly looking for a budget upgrade. I don't like how the door speakers distort/muddyup very easily(probably because of low hz). The dash speakers seem ok at best but I can't hear them clearly with the door speakers farting.

I do know that power of the stock amps are very very low, probably 15-25watts rms and 40-50watts max. With that low power, I should be looking mainly for low rms and high sensitivity drivers. With those drivers I think a "max rating" of about ~75+ watts will be good if I decide to install an amp later on.

Somebody suggested these on another thread but I am worried about the 2ohm rating. http://www.onlinecarstereo.com/CarAu...BL_GTO328.aspx
and these, 93db sensitivity.
http://www.crutchfield.com/S-ecHe0ov...ce-6032cf.html

So stock, its an 8 channel system?
All powered by the amps in the rear? or?
2 ways fronts+ stock tweeter sound ok? or should I look into components? or just eliminate the stock tweeter?
Suggestions for drivers?
Thanks!

[Chimera]

The dash speakers are 4 ohm speakers wired in parallel and driven off the hu. They yield a 2 ohm load. Doors are also 2 ohm and driven off factory amp alone. Rears are 2 ohm and are driven off the hu. Every speaker has a built-in in line crossover. The dash tweeters mount splits signal to the 3.5. Removing the tweeter also disables the 3.5

Best bang for your buck on a budget is probably a hu. Alpine, Pioneer, etc. They have higher quality signal amps in the units. Start at the root imo.

[babydriver]

Originally Posted by Chimera

The dash speakers are 4 ohm speakers wired in parallel and driven off the hu. They yield a 2 ohm load. Doors are also 2 ohm and driven off factory amp alone. Rears are 2 ohm and are driven off the hu. Every speaker has a built-in in line crossover. The dash tweeters mount splits signal to the 3.5. Removing the tweeter also disables the 3.5

Best bang for your buck on a budget is probably a hu. Alpine, Pioneer, etc. They have higher quality signal amps in the units. Start at the root imo.

Do you know of a manufacturer that can provide a head unit that will still allow the use of the LED screen? I have the navigation system installed and don't want to lose that function.

Thanks.

[babydriver]

Originally Posted by swarb

I don't understand what you are trying to explain, can you word it a little more simple? Are you trying to say I am more likely to burn out a driver underpowered than an overpowered driver?

There are two failure modes for loudspeakers, thermal overload (due to too much current/power) and excessive excursion (due to too much cone movement, again due to too much power.) Excessive excursion can lead to mechanical damage if the voice coil is driven so far that it leaves the gap and jams against it or becomes off center (scraping noise).

An amplifier is ultimately limited in power by the amount of current it can deliver. So a 15 watt amp may clip like an SOB, but the thermal load is not excessive at the voice coil if the coil is rated for, say, 50 watts. Still, who wants to listen to 50 percent distortion?

The best solution is a larger amp and a speaker that is efficient (90 dB or higher) plus has a high power handling capacity due to a larger voice coil. Also, the longer the excursion the better. These are all specified on the speaker data sheet, BTW.

A better head unit will definitely improve the sound, but bear in mind that the distortion level of an overdriven loudspeaker will greatly exceed that of even a moderately priced HU. As long as the amp is not driven into hard clipping, that is.

[Chimera]

I did not have stock nav (and have not jumped for after market either actually..) I don't know. TBH my expectation would be that the money you would spend on an adapter would be better spent on an after market solution. Hate to say it but google maps seems to totally dominate all other solutions I have even personally seen. not that I have looked a lot on that specific topic.

Originally Posted by babydriver

Do you know of a manufacturer that can provide a head unit that will still allow the use of the LED screen? I have the navigation system installed and don't want to lose that function.

Thanks.