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Discussion Starter #1
I have a question for all of the smart people in the room relative to speakers and impedance.

First, I’ve swapped out my dash speakers with an Infinity Reference 6520cx component set. These run at nominal impedance of 3ohms according to the owner’s manual. They are driven by an Alpine PDX-F4 amp. I’m considering connecting, in parallel, a set of Infinity Kappa 6x9, 693.9i, three way speakers which run at a nominal impedance of 2 ohms. With that said, Infinity claims that due to the wiring in their speakers and the speaker wires themselves, their speakers have an effective impedance of 4 ohms, or slightly higher.

My question is this: Can the 6x9s be connected in parallel, at the amplifier, without the risk of over heating the amp? I understand impedance is cut in half when speakers are wired in parallel. I also understand that I will probably have to increase the gain on the front speakers at the amp, thereby increasing the power it’s making. Per its owner’s manual, the amp is rated at an RMS @ 100 watts x 4 channels with either 4 or 2 ohm speakers connected. It drives the speakers really well as installed, and I have not had any issue with it over heating and shutting off to this point.

So again, with the build up of resistance in the wiring as Infinity claims, will it be safe for the amp to install these speakers in parallel?

Thanks in advance.
 

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Wire them up, stick a meter on them and check. The resistance isn’t really cut in half, it’s a formula. If the one set is actually 3 ohms. And the the other 2 ohms. Then the amp would see 1.2 ohms if wired in parallel. I would definitely watch heat. If one is 4 and the other 3. The amp would see 1.7. Which is still lower than the 2 ohms. Not many amps like going below 2.




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You can't measure impedence with an Ohmmeter. Impedance varies depending on the frequency.

Nevertheless I wouldn't connect those speakers in parallel, that low of a resultingimpedance could make the amplifier unstable.
 

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You can't measure impedence with an Ohmmeter. Impedance varies depending on the frequency.

Nevertheless I wouldn't connect those speakers in parallel, that low of a resultingimpedance could make the amplifier unstable.


Notice I said resistance. Not impedance. And correct, you’d need a signal generator and something that actually measures impedance.

But for car audio purposes, an ohm meter or multimeter and measuring the resistance of the voice coil is sufficient in this case.


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Discussion Starter #5
Thanks for the replies fellas. Yea I’ve read that most, if not all amps, don’t like impedance below 2. I asked due to the “effective impedance” that Infinity claims, hoping the amp would see a minimum of 2 ohms.

How about connecting them in series? That would increase the impedance and lower the volume. I’d still have to bump up the gain on the amp, but that would solve the impedance issue?
 

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Discussion Starter #7
Yes sir. That would give you 5, or 7 ohms depending on how true their information is.


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Thanks again for the input. Probably not going to try to do a series connection with the component set though. The 6x9s have built-in crossovers. To get full range on the 6x9s, I guess a wire would have to be run from the tweeter AND the woofer negative connections to the positive on the 6x9 and then back to the positives on the component set from the negative on the 6x9. Not too sure that would be a good thing to try. If I run wires just from the woofers, the crossover on the 6x9 would try to do its job and the sound would probably be muddied. This whole exercise would be a waste. So.... scrap this whole idea HA!

My reason for thinking about this was to get a little cleaner bass than the stock sub. It sounds like someone hitting a card board box now that I’ve upgraded the other speakers, and it sounds like shit... no depth. If you know what I mean. Those 6x9s put out a nice clean bass... nothing door rattling, but really good sound. They have been sitting collecting dust for a couple of years. Was just looking for a way to get better bass without spending more $$ and use something I already have.

But again thank you both for helping me explore this idea.
 

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Notice I said resistance. Not impedance. And correct, you’d need a signal generator and something that actually measures impedance.

But for car audio purposes, an ohm meter or multimeter and measuring the resistance of the voice coil is sufficient in this case.
What I noticed was that you mixed resistance and impedance in the same paragraph implying they can be treated the same, they're not.

Using an Ohmmeter to measure a speaker's DC resistance is not measuring its impedance as your post implied, they're not the same. You cannot and should never use an Ohmmeter to get any indication whatsoever as to what impedance the amplifier is going to see. The resistance of a speaker coil as measured in Ohms using a DC voltage to measure it with will always be significantly lower than its impedance resulting from an AC (audio) signal. An Ohmmeter does not belong in the same sentence where talking about impedance is concerned. Ohms and impedance are not the same, they are only distant related cousins. Been working in (now retired from) the technical side of audio, electronics, RF, etc. (for a living) since the late 60's.

The correct way to determine what impedance an amplifier will see is to do the math using only the speaker manufacturer's stated impedance of the speaker, not an Ohmmeter which is the wrong tool for the job. No, using an ohmmeter to measure the DC resistance of the voice coil is never acceptable when calculating impedance loads for the amplifier.
 

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What I noticed was that you mixed resistance and impedance in the same paragraph implying they can be treated the same, they're not.

Using an Ohmmeter to measure a speaker's DC resistance is not measuring its impedance as your post implied, they're not the same. You cannot and should never use an Ohmmeter to get any indication whatsoever as to what impedance the amplifier is going to see. The resistance of a speaker coil as measured in Ohms using a DC voltage to measure it with will always be significantly lower than its impedance resulting from an AC (audio) signal. An Ohmmeter does not belong in the same sentence where talking about impedance is concerned. Ohms and impedance are not the same, they are only distant related cousins. Been working in (now retired from) the technical side of audio, electronics, RF, etc. (for a living) since the late 60's.

The correct way to determine what impedance an amplifier will see is to do the math using only the speaker manufacturer's stated impedance of the speaker, not an Ohmmeter which is the wrong tool for the job. No, using an ohmmeter to measure the DC resistance of the voice coil is never acceptable when calculating impedance loads for the amplifier.


I appreciate your experience and chiming in to help this fellow Jeeper. I am aware of the difference between resistance and impedance. I personally did not feel the need to get into the minutiae of DC vs AC circuits, reactance, etc. I believed that for the purposes he was trying to achieve, the basic steps I outlined were more than sufficient.

However, great information. And I’m sure it may help someone in the future that may wish to see it.



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Discussion Starter #10
You can't measure impedence with an Ohmmeter. Impedance varies depending on the frequency.

Nevertheless I wouldn't connect those speakers in parallel, that low of a resultingimpedance could make the amplifier unstable.
This one may do the trick. Pioneer says it’s stable @125 Watts x 4 channels at 1 ohm. Sonic electronics has it for about 140 bux with free shipping. Might be worth the purchase, and it’s not too pricey.... get great reviews too over a few years.
 

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Discussion Starter #13
Let us know how it sounds when done!

I’m planning an amp change soon myself.


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First.... sorry for the length of this response.

So.... I got the amp on Friday. Didn’t have time to mess with it Saturday. Sunday morning I opened it up, and began to really read the owners manual. In which, there is direction to NOT hook up 2 ohm speakers in parallel to obtain less than 2 ohms impedance. So I’m like, shit, I should have read this owners manual more in depth prior to buying. Shame on me. So, just to get a feel for how those 6x9s would sounnd, I disconnected the roll bar speakers from the installed Alpine amp and ran new wire from that amp to the 6x9s; placing them in the floor behind the seats. I have a two door with the back seat removed, so the rear foot wells are a great place for them. I also removed the stock sub, disconnected the 4 plugs from it, and reinstalled it in its hole. OMG did those 6x9s REALLY wake that system up! Great bass, and fantastic sound from the whole system. When I’m driving around, even at 65 MPH, top down, it sounds like I’m in a sound bubble. It’s crisp, clear and unbelievable. It sounds better top-down than top up. Those 6x9s definitely need to be a permanent addition, but I took em back out for now.

Now, I’m not sure what to do with the new amp. It has not been installed or hooked up. It’s NIB. I do have a question.... The new amp has RCA outputs. I’m assuming those outputs are for chaining together more than one amp to feed more than one set of speakers? The Alpine (old one) does not have outputs, but does have RCA inputs. Could I use the Pioneer (new one) as the primary amp, fed from the head unit with the dash and sound bar speakers connected to it. Then install the old amp, feed it from the Pioneer via RCA cables, and hook the 6x9s to it? That would not be considered “parallel” would it? That way I would have dash and sound bar speakers along with the 6x9s... if I could figure a way to mount them securely and out of sight.

Or should I just mount the 6x9s somehow, return the Pioneer amp to Crutchfield’s, then remove the sound bar speakers and sell them? Those Kappas are only a few months old.

I learned that I should have bought 4 ohm speakers from all of this, but those Kappas sound freaking awesome when driven by the right gear. I spend a lot of time in my ride and cannot stand poor sound.... :pullinghair:
 

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What you want to do here looks like it would work. The problem is how it is going to set your sound stage. The output of the amp looks to be tied to channel A which in most cases is the front. That means that 4 of your speakers would be tied to the front and 2 to the rear. IF you keep you fader neutral that would not be a big issue.

The other way would be to go with something like a DM-608 a full featured DSP which will allow for 8 channels out. This is the way I would go but it is more money.
 
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What Terry said. In general you have the right idea.


Different but related topic...

Be careful running any speaker without an enclosure. I know this was just an initial test but you can damage speakers if you turn up the volume or bass when your speakers are running open baffle or free air. They need an enclosure to sort of cushion and help control the excursion of the woofer. But as a quick check at low volume you'll be fine.
 

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Discussion Starter #16
What you want to do here looks like it would work. The problem is how it is going to set your sound stage. The output of the amp looks to be tied to channel A which in most cases is the front. That means that 4 of your speakers would be tied to the front and 2 to the rear. IF you keep you fader neutral that would not be a big issue.

The other way would be to go with something like a DM-608 a full featured DSP which will allow for 8 channels out. This is the way I would go but it is more money.
Hey Terry, thank you for the input. Yes I see what you’re saying. However, in order to fix that issue, couldn’t I just wire the sound bar speakers into channel “A” on the amp, and the fronts into channel “B”?

I mean the amp doesn’t care right? Nor do the speakers? As long as the speakers are properly connected to the amp?

As for the fader... it’s normally at neutral depending on the song, and maybe a click to the front or back sometimes.
 

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What Terry said. In general you have the right idea.


Different but related topic...

Be careful running any speaker without an enclosure. I know this was just an initial test but you can damage speakers if you turn up the volume or bass when your speakers are running open baffle or free air. They need an enclosure to sort of cushion and help control the excursion of the woofer. But as a quick check at low volume you'll be fine.
Hey crazychile, thank you as well. That’s good to know. I’m assuming you’re referring to the 6x9s I tried out. Yea... they are in enclosures already, similar to the attached pic.

I just laid them in the foot wells, pointing up to get a good feel for how they would sound. If I decide to put them back in and permanently install them into the system at that location, I’ll build enclosures for them that are more secure and not so easily recognizable for what they are.
 

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Hey Terry, thank you for the input. Yes I see what you’re saying. However, in order to fix that issue, couldn’t I just wire the sound bar speakers into channel “A” on the amp, and the fronts into channel “B”?

I mean the amp doesn’t care right? Nor do the speakers? As long as the speakers are properly connected to the amp?

As for the fader... it’s normally at neutral depending on the song, and maybe a click to the front or back sometimes.
Yes as long as you know you have it reversed, fade to rear is actually fade to front. Also if your head unit as time delays make sure you reverse it there as well.
 

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Yes as long as you know you have it reversed, fade to rear is actually fade to front. Also if your head unit as time delays make sure you reverse it there as well.
Hmmm... not sure what a time delay is; nor if my H/U has it. It’s a Pioneer AVH-X5600BHS. Would the option to reverse it be in the system set up options?
 

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I will look a little later to night have to finish the deck.
 
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