Are the 2 ohm Infinity Reference 9633cf speakers good choice?

The infinity's are designed to use the factory wiring in conjunction with the impedance of the voice coils. So what your stereo will see is 4 ohms of impedance total, stead of say 5ohms because you're using the factory 20ga wiring. This along with the infinity's having some of the highest sensitivity ratings on the market for the price makes them my pick for speakers to consider.

I would probably lean towards infinity reference rather than kappa's, due to the lower power requirements. Kappa's are nice but from what i researched, most people are saying you need a small amp to feed them enough juice to produce good bass out of them. I wish manufacturers would provide charts with frequencies and power input into the speaker so people could get a better idea of matching the speakers to the source.

 

What manufacturer in their right mind matches impedence with the assumption of you using existing substandard wire gauge?!! Half of the power is being dropped across the wire and never even makes it to the speaker. Not to mention the roll off of both hi and lo frequencies and the fact that you're going to lose at least 3-6db's of signal. The signal attenuation alone will be a noticeable volume loss. If you are going to the trouble, might as well do it right, up the wire gauge to 16 (plenty big enough for a full range type speaker) and match it with the proper 4 ohm speaker load. Load mismatch is a huge waste. My neighbors kid across the street was asking me why his lights dimmed when he had a cap in the system. I told him to replace the crap 20 gauge stuff he was using with a thicker wire. Forgo the Monster cable and by a roll of 14-16gauge at Lowes, same wire, 1/3 the cost. He was able to cut back on the volume knob and get the same output without blowing fuses and dimming lights.

Speaker impedence is a dynamic value. They see low freqs. As almost a dead short and hi freqs as high as 30-40 ohms.

 

I suspect the factory wiring is thicker than 20 gauge. I would guess it is roughly 18 gauge. Of course, the Japanese use wire size in sq mm, so it isn't exact. I think the OEM design of putting the dash speakers in parallel with the front door speakers is pretty stupid. I know there is the blocking capacitor, but it is a big hack. I was fearful that putting a low impedance load on the OEM head unit might cook it, so I added a 2 ohm resistor in series with both the door speakers and the dash speakers (as well as a much bigger capacitor to allow lower frequencies to get to the dash) to reduce the probability of cooking my overpriced OEM head unit.

I think the idea of 2 ohm speakers in general is incredibly stupid. Even if you use thicker wires, you will have twice the power loss as you would with 4 ohm speakers. Perhaps before switching power supplies 4 ohm speakers made some sense for cars, but today they make no sense. Before switching power supplies cheap amps were limited to swinging 12 volts. With 4 ohm speakers, you could get twice the power as 8 ohm speakers. Today, switching power supplies are quite cheap and efficient. Another issue is power loss in connectors. All connectors have some resistance. 2 ohm speakers will double the power loss in the connectors. I have seen far more poorly made crimp connectors in car stereos than well made connectors. I have a good ratcheting crimp tool.

I am in the process of rewiring my stereo. I replaced all the wires with 16 gauge wiring. The woofers got 14 gauge wires. I have the JBL MS-8, so each speaker location will have its own amp.

As for the efficiency of 2 ohm speakers, look carefully, many are spec'ed with the voltage that a 4 ohm speaker would use for 1 watt, not a 1 watt input for the 2 ohm speakers. This will add 3db of efficiency to the spec, without changing the real efficiency. According to crutchfield, "Sensitivity 94 dB at 2.83 volts", which means 91db at 1 watt input. My cheap kenwood speakers I bought from crutchfield are 91db at 1 watt. So the infinity speakers are nothing special for efficiency.

Try to find a good manufacturer of drivers for non car audio that makes 2 ohm speakers. I suspect there are none. I wonder why that is?

 

Good point about connections. If I do a speaker upgrade I will solder the speaker connections. If I replace speaker wire I will also separate it (split the parallel conductors apart like is done at the ends at the push on connectors) and twist it from the amp to the speaker to decrease any stray capacitance. Doing this decreases both noise (non linear distortion) and signal losses on the high end. Split it down to the RCA connection.

The biggest bang for the buck is the speaker. Jim Lansing (JBL) did this back in the 70's by winding the voice coil with flat instead of round wire. Less gap therefore less loss in the motor (voice coil). He built a 101db speaker back when that was unheard of.

Speaker sensitivity should be a 1 watt at 1 meter away measurement. .125v across 8 ohms is 1 watt output. Like I mentioned before, most of the "best" specs are cheery picked by the marketing department when it comes to sensitivity (efficiency) and THD. If you have 25 watts per channel to work with, use 50 watt speakers. Overdoing it takes a lot out of the equation.

If you really want to maximize things, start with the pre amp stage and voice it from there. Increase the first and second stage emitter bypass caps in the amp a step and decrease its resistance a step to let more bass pass in the beginning. Leave the output (power) section alone (the blocking cap) because it's already biased to pass whatever comes into it in the first place.

Bottom line. It's all cumulative. Weak links in the system can make up a lot. I have made cheesy little guitar amps sound like Joe Walsh's playing "Life's Been Good" by optimizing everything.

 

You can't design and sell based on "might-as-well". You have to sell based on how a majority of your buyers are going to use it. Most will simply use the factory wiring, only audiophiles will upgrade the cars speaker wires. I'm sure a company as well established as infinity with a reputation for making decent products has done their homework on this. Based on how most buyers will use it, they probably did tons of testing and found it was better to lower the total impedance and get more juice from the amplifier, then it was to use a traditional 4ohm speaker combined with the impedance of factory 20-22awg wiring. I'm really doubting they converted most of their speaker line to this without proper testing and validation. Nearly all aftermarket amps will handle 2ohms no problem, and that's traditonally when people start upgrading speaker wires, not traditionally when they power speakers with just the headunit.

 

Put 2 of these in the back and you won't need anything else! About 20lbs each (at least the AlNiCo magnets, e series are the round cheaper ceramics we're all used to seeing). These were the first to break 100db's. Ribbed cones, aluminum dome (really shoots out the highs), vented voice coil and cloth surrounds.

Recones are always a crap shoot, though.

 

Those are $225 for rebuilt speakers. We're talking about $90 speakers. Can those even operate as free air speakers?

 

Yea no problem. If they were original cones they would be about 225.00 a piece. Work great in an open back guitar amp, closed back, or ported box. These are still considered THE primer Hi Fi and professional guitar amp speaker. If you wanted to send sub frequencies to it (them) a closed cabinet will yield better damping which let's you drive them with more power. At 101db it would be about twice as loud as a 92db speaker. It takes about 7 times the power to double volume or about 6-9db's.

 

no.

Stick with 4 ohms

 

So Infinity 'did their homework' and tested all the OEM head units and found out that none of them would burn out when presented with low impedance loads? And all cars have factory 20-22 awg wiring?

I don't know where you get these ideas, but I fear they have no basis in reality.
OEM head units are made as cheaply as possible to work with OEM speakers.
And even though the prius has pretty small wiring, I would guess it is about 18 gauge.

2 ohm speakers are dumb. I doubt that OEM wiring, with thin wires and crappy connectors adds 2 ohms of impedance.
I suspect anyone buying these speakers will change the wiring and likely add an amplifier.
Most OEM amps are pretty lame. I suspect the prius is good for about 5 w RMS per channel.
Even the magic 'greenedge' amp is only good for 120 watts *total*. Assuming 6 channels, that is 20 w per channel. So clearly the non greenedge is significantly less...

 

I would highly recommend that you stay away from those speakers if you plan on having the factory HU power them. Almost every aftermarket speaker on the market (JL, Infinity, Kicker, Alpine, MB Quart, Focal, etc)has been designed to be used with an external amplifier. Buying upgraded speakers without using a quality amplifier is a waste of money. You also want to invest in a better quality speaker up front vs the back of your car as you will barely hear the sound coming from your back doors with the way the Prius is designed. Kappa's are the top of the line and then Reference.

 

I didn't say "all" in reference to the OEM unit. I didn't even talk specifically about an oem head unit, most people upgrade speakers and headunits together. You're putting words in my mouth, then arguing against the words that you inserted??? You're one of those people i hate arguing with, just like my ex girlfriend, which twists all the relevant statements and argues against them. You're also making assumption and "guessing" it's 18guage. I work with wiring all day long, 18 and 20 guage look very similar, and depending on the type, can have various thicknesses of insulation and "look" like 18 gauge. I couldn't tell you either way without looking directly at it myself, but even 18 guage has a max recommended length of 5 feet for a 4 ohm load due to the damping factor. It has a max recommend distance of 13 feet due to insertion loss. Infinity doesn't specifically state 20awg, i just threw that number out there hypothecially because it seems typical from many of my own cars i've done. Whenever i upgrade to an amp, i always run 14awg wire, but i won't be using an amp in the prius, just a headunit.

"I don't know where you get these ideas, but I fear they have no basis in reality.???" I'm an engineer and i worked in product testing and validation for 3-4 years for my company. I really can't imagine any engineer would design any kind of product like this without some extensive testing in a lab, and not show a performance analysis with graphs to show advantages. When we put out a product, i have to show graphs which demonstrate that it either equals, or outperforms the previous design even if it's a cost reduction. Or if it's a new product, it has to equal or exceed the performance of our competitors based on value. But since the reference and kappa lineup has been around for years, i can't imagine that infinity would just dump the traditional 4 ohm speaker without doing extensive testing. I'm sure they have tons of graphs and powerpoints to prove some sort of advantage. If they screwed up any cars and had to recall the product, there would be plenty of people fired, so they better make sure it's right. I don't know where you got your idea that infinity would just change up their entire product lineup without doing any kind of testing???? That's a quick way to bankruptcy.

Also, speaker impedance is not a simple figure, it varies with several factors. The amplifier output is also not so simple, and can also vary with different load characteristics. Here's a chart of a typical 8 ohm impedance speaker, as you can see, it can go upwards of 40ohms depending on the frequency.


With the kind of money infinity makes, they can afford a few engineers to do R&D. To say they didn't do their homework on their best selling reference and kappa lines is really absurd.

 

Lets do some math.
20 feet os 22 gauge (that is the resistance of a 10 foot run of 2 conductor) = 0.323 ohms
124 feet yields 2.001 ohms.
200 feet of 20 gauge yields 2.03 ohms.

Now this is ignoring the resistance of connectors.

Does anyone think that there is 60 feet of 2 conductor wiring that is 22 gauge going to each speaker?
If not, the idea of 2 ohms of wiring loss is baloney.

As for Infinity, I suspect they do what they do based on marketing and very little else.
Their speakers are generally boring, and few consider them high quality.
They are quite good at marketing, and very little else.
I think of them as the monster cable of speakers.
I haven't met arnie nudell, but his companies and products are uninspiring.

Your speaker impedance graph likely shows a 3 way system. It also shows the impedance curve of 2 different systems.
While it is nice, amplifiers generally have a minimum stable load, and it is generally insensitive to frequency.
Feel free to use whatever you want with your OEM head unit, but if it was me, I would worry about blowing the output transistors with a low
load.

 

The red line is just 2 of the same speaker in parallel. Here's a link to the article: AV and Automation Industry eMagazine - Speaker Impedance, Your Amplifier And You. | HomeToys

No one is saying there's a 2ohm impedance in the wires except for you. Resistance and impedance aren't the same thing, impedance has a frequency component to it. Infinity quotes a 2ohm impedance on the speaker which could be at any frequency we don't know, as you can see in the graph, it's not a simple linear interpolation. (2ohm wire resistance) + (2ohm speaker impedance) != (4ohm impedance). It doesn't work that way.

Like i said, i don't know the true answer to the question of whether or not the "True 4ohm" is just snake oil. But no company as large as infinity would go out and sell crap on purpose and rely on clever marketing to make sales. They would diminish their brand over time, and go out of business very quickly. I wouldn't put infinity on the high end audio scale, but i would put them in as one of the better value brands. They do work well for the price, and their oem audio systems do sound pretty good compared with other oem audio systems in vehicles. Like them or not, they do have a solid reputation, maybe not to audiophiles who stick their noses up at many brands, but infinity is solid. Why would they compromise their integrity by doing what you suggest? That's a dumb way to do business, and will throw yourself into bankruptcy down the road.

Most likely, they wouldn't make a 2ohm speaker just to be able to market "true 4ohm", more likely they would have left it as a 4ohm speaker, and changed the sensitivity curve a little(like in the graph above), to be able to pick a point on the plot and say it goes down as far as 2 ohm, but within most of the range, it's more like a 4ohm speaker. This makes more sense, and is probably why it's safe to use with oem head units.

Also, if it's going to do what you suggest and blow head units, why hasn't anyone heard of this happening??? Retailers would pull the speakers off the shelves if this were to happen. Infinity would lose millions in current sales, and millions in future sales.

 

So no one says it is a 4 ohm load?
Infinity Reference 9633cf 6"x9" 3-way car speakers at Crutchfield.com
says "True Four Ohm Impedance technology: speaker's 2-ohm impedance combines with speaker wire impedance for a 4-ohm load". So crutchfield is no one? I presume if Infinity didn't like what they were saying, they would fix it.

I am pretty sure that few people are using these 2 ohm speakers with the factory amps. I haven't seen an impedance chart, so I don't know what the impedance really is.

I think it is really dishonest to spec the efficiency at 2 watts, rather than everyone who specs efficiency at 1 watt.

 

That's crutchfield, it doesn't say that on infinity's website, crutchfield always tries to dummy things down into laymans terms. I just looked at several infinity speaker lines, many state a "Nominal 2ohm Impedance" to compensate for thin speaker wire impedance. Using the term nominal means they can just pick a point at any frequency and say the impedance is that.

That's really hard to say. I'm willing to be that most are using these speakers with aftermarket headunits, few are using them(epescially the reference line) with aftermarket amps. But there are still some using them with factory OEM headunits these days because of the fully integrated screens on dashes now. Many people just like to stream music from their phone or mp3 player, so there isn't that push to upgrade head units.

 

Kappa 462.9cfp - Infinity

"True Four Ohms— All Kappa speakers feature two ohm voice coils. Original
factory-installed speaker wiring in many cars is 18-22 gauge. This wire,
and heating in the voice coil when power is applied, increase the
impedance “seen” by the amplifier or head unit. The impedance of Kappa
Speakers has been adjusted to compensate for this increase and can be
safely driven by any head unit."

Sounds close enough to what crutchfield says. If the speakers ar 2 ohms, and Infinity says "true 4 ohm", that means the wires plus the heating in the voice coils makes an additional 2 ohms - which is pure baloney. I told you this was marketing BS.

 

You're trying to play the literal game and sidestepping the point. "True Four Ohms" is probably a term created by their marketing arm. When i invent or tweak something, our marketing people try to come up with a new name for it, to sell it. But engineering wouldn't do that, which is why there are no specifics in the paragraph. Never do they say the wires themselves are the other 2ohms of impedance. The infinity reference X speakers are 3ohms, yet they still advertise a "true 4 ohm" architecture, i presume with the same 18-22 guage wiring. Obviously, the math hear is not linear like you're suggesting. There are several variables, and i'm sure several charts to determine the speaker rating. I highly doubt, it's a simple 2 ohm speaker. I don't think it's simple marketing hype and nothing is changed in the product. I think engineers did some tweaking, then handed it off to sales and marketing, they created the rest.

 

So now you highly doubt infinity, which says it is a 2 ohm voice coil. Except the the wires from the coil to the spider, there is nothing else. So infinity are basically saying it is a 2 ohm speaker. So you don't trust infinity at all?

Well neither do I. It is 99% marketing BS.

You kept on saying that the stuff I was claiming didn't exits. I have URLs from crutchfiend and infinity saying what you say doesn't exist. What else do you want? Crutchfield is one of the largest car audio suppliers, and Infinity makes the stuff. I still maintain if crutchfield said something factually incorrect, their suppliers would almost certainly notice and tell them to fix it.

2 ohm speakers are dumb. Really dumb. Perhaps excusable when running 2 woofers in parallel with an appropriate amp, but that is about it. As for infinity, since they quote their efficiency numbers at 2 watts rather than 1 watt that everyone else uses, that clearly shows they are market driven at best.