If I put a resistor inline with a speaker will it affect the dynamic impedence of the speaker? As in a 4 ohm resistor with a 4 ohm speaker make an 8 ohm load?
I'm wondering cause partsexpress has one hell of a deal on buyout Onkyo car speakers (read not great speakers, but damn cheap), but the one I was looking at was 2 ohms, and I don't think my stock head unit would like so much.
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=269-727
figured if it worked than a 50 cent resistor and $2.27 speaker would be a good deal
I'm wondering cause partsexpress has one hell of a deal on buyout Onkyo car speakers (read not great speakers, but damn cheap), but the one I was looking at was 2 ohms, and I don't think my stock head unit would like so much.
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=269-727
figured if it worked than a 50 cent resistor and $2.27 speaker would be a good deal
The benefit would be that your stereo amp will see an 8 Ohm load and be happy. The tradeoff is the output power through the speaker will be only 1/4, or 6dB less than, what you would have with a regular 8 Ohm speaker, assuming equal efficiency of the speakers. That may be a problem because that 2 Ohm speaker may not be efficient. And, you would probably be less concerned that an inline resistor lowers the damping factor acting on the speaker, muddying the response. 
Since these are car speakers and you mention "stock head unit", I assume you mean to put these into your car. In that case you want to raise the impedance to around 4 ohms. For that, you need a 3 ohm resistor.
If:
X = impedance of the speaker
R = resistance of the resistor
The impedance of the total unit will be given by the following formula:
square root of (X squared + R squared) =
square root of (2 squared + 3 squared) = 3.6 ohms. Close enough to 4 ohms.
The speaker has a Qts of near 1. Put that resistor in series, and your Q will go way up. So instead of being near the midpoint around 65 Hz-which is the Fs-the speaker will boom quite a bit near there. It will be about 4 or 6 dB up or higher around 65 Hz. You might not like that, or maybe you will. Maybe you have an equalizer on board that you can take that down. On the other hand, a lot of people simply like to crank the bass up on their car speakers anyway, so your halfway there to start with.
The following chart gives response shapes for systems with final Q numbers. With the resostor, your Qtc will be either 1.5, 2.0, or higher. You can see how it booms over the midpoint.
http://www.diyaudio.com/forums/showthread.php?threadid=5669&highlight=chart+Qtc
Bass might be emphasized, but it will NOT be lean and tight. Rather boomy. But again, maybe you might like it.
If you can find a place in the car to hook up a second pair that you have wired in series, then you don't have to worry about any of that. The speakers will play just as they are supposed to, and your car's head unit will see a nice 4 ohm load without any resistors necessary.
In short, hook up the resistor and it will play safely. Whether you like the sound or not is open to question. At these prices, you can afford to experiment.
If:
X = impedance of the speaker
R = resistance of the resistor
The impedance of the total unit will be given by the following formula:
square root of (X squared + R squared) =
square root of (2 squared + 3 squared) = 3.6 ohms. Close enough to 4 ohms.
The speaker has a Qts of near 1. Put that resistor in series, and your Q will go way up. So instead of being near the midpoint around 65 Hz-which is the Fs-the speaker will boom quite a bit near there. It will be about 4 or 6 dB up or higher around 65 Hz. You might not like that, or maybe you will. Maybe you have an equalizer on board that you can take that down. On the other hand, a lot of people simply like to crank the bass up on their car speakers anyway, so your halfway there to start with.
The following chart gives response shapes for systems with final Q numbers. With the resostor, your Qtc will be either 1.5, 2.0, or higher. You can see how it booms over the midpoint.
http://www.diyaudio.com/forums/showthread.php?threadid=5669&highlight=chart+Qtc
Bass might be emphasized, but it will NOT be lean and tight. Rather boomy. But again, maybe you might like it.
If you can find a place in the car to hook up a second pair that you have wired in series, then you don't have to worry about any of that. The speakers will play just as they are supposed to, and your car's head unit will see a nice 4 ohm load without any resistors necessary.
In short, hook up the resistor and it will play safely. Whether you like the sound or not is open to question. At these prices, you can afford to experiment.
Thanks for the info. I dont really care about the fidelity in car stereo, so if it has a little accented bass in the rear (these would go in the rear deck), then I can either live with it or fade forward a little. But even so a 65 hz boom is much more acceptable than say a 200 or 400 hz boom. And like I said for about $6 total for the pair, its not like I can complain much.
I just like the fact that the speaker itself is alot better quality than what it came with stock (96 Integra 4 door)
I just like the fact that the speaker itself is alot better quality than what it came with stock (96 Integra 4 door)
Well, I cannot argue with your thinking. For 6 bucks-why not?
Since you are putting these into the rear deck, there is one alternative in case you want to go hi fi with these.
Isobaric.
This is where you make a little enclosure there one speaker is hooked up behind another. The idea is that the rear speaker goes back and forth and gives the front speaker a nice even air load on the backstroke. The rear of the rear speaker would fire into the trunk.
I've never built an isobaric configuration, but many people in this forum have vouched that they do work. It's a proven configuration.
If you hook them up in series, you will have a 4 ohm impedance for your head unit to drive.
Here is an illustration. The front speaker would of course be attached to the rear deck.
The speakers can also be hooked up face-to-face, but that might not be sightly in a car.
Anyway, if you care to do it, the isobaric idea will give better fidelity in the hokup while giving you a 4 ohm load. Remember to hook them up in series.
For six bucks a pair, it might be worth it.
Since you are putting these into the rear deck, there is one alternative in case you want to go hi fi with these.
Isobaric.
This is where you make a little enclosure there one speaker is hooked up behind another. The idea is that the rear speaker goes back and forth and gives the front speaker a nice even air load on the backstroke. The rear of the rear speaker would fire into the trunk.
I've never built an isobaric configuration, but many people in this forum have vouched that they do work. It's a proven configuration.
If you hook them up in series, you will have a 4 ohm impedance for your head unit to drive.
Here is an illustration. The front speaker would of course be attached to the rear deck.
The speakers can also be hooked up face-to-face, but that might not be sightly in a car.
Anyway, if you care to do it, the isobaric idea will give better fidelity in the hokup while giving you a 4 ohm load. Remember to hook them up in series.
For six bucks a pair, it might be worth it.
Attachments
So if the resistor raises the Q of the speaker at the resonance freq, then could this be an easy way to reinforce a subwoofers response? I mean could you make a sub have more output down low, since your not worring about anything above 80-100 Hz anyways? Seems like an easy way to make a 10" or 8" have more low end extension, by bringing back the freq that are dwindling away.
Well, Im making a Sonotube sub for home, and I have a bunch of 8" driver sitting around and was thinking maybe this would extend the lower freq's so that it could easily play down to ~40 Hz. But of course I would be using at least a 50 watt amp on those, so thats what I was wondering about the resistor. Parts Express sells "Audio Dummy Load" resistors that can handle up to 100 or 200 watts (pn# 019-015)
Haha...sorry guys. Yes originally I was wondering what the effects would be on a pair of car speakers, but then as you guys started talking about how the output could be accented down low with the high Q, I began to wonder if that could be used to your advantage in a subwoofer application. Say two four ohm drivers in parrellel to make 2 ohms (or one 4 ohm DVC driver) and then put a 2 ohm resistor in series to make it back to 4 ohms and have accented base.
But only to use the accent to recover where the driver is strarting to fall off. Not to make it real boomy. If I had a server or something I'd post a drawning showing what I mean.
But only to use the accent to recover where the driver is strarting to fall off. Not to make it real boomy. If I had a server or something I'd post a drawning showing what I mean.
Westrock:
Now that it is clear that you have 2 projects going, it is not necessary to post a graphic. I understand what you mean.
Normally, a resistor in series with a speaker, while making the bass frquencies higher in respect to midrange frequencies, also cuts the overall output as well, so you get less bass in the end. You just get a lot less midrange as well.
However, putting them in parallel and then adding the series resistor might change things. Not sure how, but I would have to work it out. Who knows-maybe you are onto something.
If it is advisable, which we don't know, then what you are talking about would be best with low Q speakers, which most speakers are. A speaker with a Qts of .5 is 6 dB down at resonance-and it is the resonance that would be boosted the most. The only reason that your car speaker is going to sound boomy is that it has a Qts of 1, which the resistor will raise. Generally, Qts much over 1 sounds boomy. However, to raise the Qts from .5 up to 1 should not sound boomy at all.
I'll get back to you on this. If anybody knows anything about this configuration-parralleling two 4 ohm speakers to make a 2 ohm load, then adding a 3 ohm series resistor in order to raise the Qts of the system to near 1-please jump right in.
Now that it is clear that you have 2 projects going, it is not necessary to post a graphic. I understand what you mean.
Normally, a resistor in series with a speaker, while making the bass frquencies higher in respect to midrange frequencies, also cuts the overall output as well, so you get less bass in the end. You just get a lot less midrange as well.
However, putting them in parallel and then adding the series resistor might change things. Not sure how, but I would have to work it out. Who knows-maybe you are onto something.
If it is advisable, which we don't know, then what you are talking about would be best with low Q speakers, which most speakers are. A speaker with a Qts of .5 is 6 dB down at resonance-and it is the resonance that would be boosted the most. The only reason that your car speaker is going to sound boomy is that it has a Qts of 1, which the resistor will raise. Generally, Qts much over 1 sounds boomy. However, to raise the Qts from .5 up to 1 should not sound boomy at all.
I'll get back to you on this. If anybody knows anything about this configuration-parralleling two 4 ohm speakers to make a 2 ohm load, then adding a 3 ohm series resistor in order to raise the Qts of the system to near 1-please jump right in.
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