Do speakers have a lower impedance before break in? BIG PROBLEMS!!!!!

[annunaki]

4.6 ohms is a very low DC resistance for an "8 ohm" speaker. This should be classified as a 6 ohm speaker for all intents & purposes.

Most 8 ohm nominal units will have a resting DC resistance of 6.0 ohms or higher.

With a minimum impedance of 3 ohms, it definitely acts much more like a 6 ohm speaker. Throw in manufacturing tolorances and you could have a speaker dip to the 2 ohm range with this model.

It really stinks when speaker manufacturers cannot be honest and accurate with their impedance ratings, amongst everything else out there.

Take Axiom for example. At least they are not hiding the fact that they have 4 ohm speakers. PSB is another, they typically use a 6 ohm speaker.

 

[Loren42]

4.6 ohms is a very low DC resistance for an "8 ohm" speaker.

Well, that does include the crossover in the circuit, but it does seem to be a little lower than what I would expect.

However, that is an empirical measurement made by the owner with some unknown meter and we have no information on either the quality of the meter, its calibration, nor quality of the measurement itself.

So, I would not bet my house just yet.

Fair to say that the speaker should not be the root cause of the amp's failure assuming that the speakers were correctly connected and there was nothing wrong with the speakers themselves.

 

[Highbar]

Yes it is a sad day for the old Denon. I'm pretty sure that they will be able to repair it without much trouble but I still wouldn't use it with those speakers. I agree that they should probably be considered 6Ohm speakers due to how low they drop. I think it's time to start looking for a power amp and to either use the Denon (if it has pre-outs) or another mid level receiver as a pre-pro for the amp. Sorry for the bad news.

 

[annunaki]

Well, that does include the crossover in the circuit, but it does seem to be a little lower than what I would expect.

However, that is an empirical measurement made by the owner with some unknown meter and we have no information on either the quality of the meter, its calibration, nor quality of the measurement itself.

So, I would not bet my house just yet.

Fair to say that the speaker should not be the root cause of the amp's failure assuming that the speakers were correctly connected and there was nothing wrong with the speakers themselves.

How incorrect should most DMM's be??? A 5% variance is 4.37 ohms on the low side and 4.83 ohms on the high side. This is not a difficult measurment for even a novice to screw up. In any case, it is still a very low measurement for a 8 ohm nominal speaker.

As long as no wire strands were shorting to the receiver's chasis or to each other, things point to low impedance as a contributing factor.

 

[xrodney]

I never actualy tryed measure speaker DC vs AC resistance aka impedance, but i do pretty much know that they can be different in sense on several decades.
It all depend on material and construction of speaker driver and crossover alsso add little thing to it.

In a coil or capacitor, the reactance changes due to the way the component works with electricity. A capacitor, will increase its resistance as the frequency gets lower. A coil on the other hand, will increase it's resistance as the frequency gets higher. They will both continue like this until their resistance is so very high, that no useable current will pass, at which point they are said to be "saturated". In a normal resistor, at any given frequency, we can say that it's resistance is still the same. When graphed, the value of a resistor will be a straight line across the graph. In a reactive component, however, the line will gently slope upward, or downward, with frequency.

This is reactance. Reactance is necessary for crossovers to do their job. Whenever you look inside a crossover (passive crossover, at least), you will see usually nothing more than a few coils and capacitors, and occasionally the odd sand block resistor. Remember, coils resist high frequencies, and capacitors resist low frequencies. When the two are combined, they form crossover networks. A crossover network typically uses a capacitor to keep low frequencies from going to a tweeter, and a coil to keep high frequencies from going to a woofer.

Another component that has reactance, is the speaker itself. A speaker's voice coil behaves electrically just like a coil in a crossover network. Because of this, speaker designers face special problems when designing midranges and tweeters based on voice coil drivers. Also, due to it's reactance, a speaker is almost never at it's rated "Impedance" (a word often used incorrectly by speaker manufacturers). When a speaker is measured at 4 ohms, it is measured using a device that puts out DC current to do the measuring. The only other time the subwoofer will have anything near 4 ohms is when it is at resonance. The rest of the time, the voice coils impedance is very high.

Crossover should be designed well enough that it actually prevent speaker goes into resonance.

Even if you measure DC resistance around 3 ohms, it still doesn't meant it will not have more then 8 ohm when driven by your receiver.

Did OP actually measured resistance of whole speaker including crossover or took speaker apart and measured driver coils separately ?

Only really revealing way how to measure speaker impedance is to use frequency generator and measure current and voltage using AC signal with several different frequencies.
This is actually what speaker manufacturers or test labs do, and 4/6/8 ohm impedance specified by manufacturer is simple "average or approximated" value of measured impedance in full frequency spectrum they should be able provide.

 

[gixxerific]

Thanks for all the replies I'm always learning.

I know the speakers played a part in it, but I know it was the receivers fault or rather a combination of the two. In the end it is my fault, I bought that receiver about 5 years ago while just window shopping. It was near x-mas, it was last years floor model for super cheap. I didn't even think to check if it was stable to 4 ohm instead of the six it is labeled at. Believe me I know all about taking labels with a grain of salt.

I will not be fixing the receiver again, I have my Onkyo running them right now though with less quality signal transfer and well it is 15 or so yrs old. But it is running them strong. Too bad I haven't really had time to listen, too much going on. right now. I will be looking into a new recv'r or pre\pro (4ohm). But it is kind of an emergency at this point. Thing is I just spent a boatload on speakers soooooo........... Never fear I will work something out.

To those of you not familiar with Focal they are very highly regarded, I don't believe they would in any way would purposely claim false readings, or for that matter use inferior equipment to test those readings. Everything in their speakers are made in house no outsourcing.

Again thanks for the replies, anyone want a Denon 2106 last time i had it fixed it was $350.

Dono

 

[lsiberian]

Thanks for all the replies I'm always learning.

I know the speakers played a part in it, but I know it was the receivers fault or rather a combination of the two. In the end it is my fault, I bought that receiver about 5 years ago while just window shopping. It was near x-mas, it was last years floor model for super cheap. I didn't even think to check if it was stable to 4 ohm instead of the six it is labeled at. Believe me I know all about taking labels with a grain of salt.

I will not be fixing the receiver again, I have my Onkyo running them right now though with less quality signal transfer and well it is 15 or so yrs old. But it is running them strong. Too bad I haven't really had time to listen, too much going on. right now. I will be looking into a new recv'r or pre\pro (4ohm). But it is kind of an emergency at this point. Thing is I just spent a boatload on speakers soooooo........... Never fear I will work something out.

To those of you not familiar with Focal they are very highly regarded, I don't believe they would in any way would purposely claim false readings, or for that matter use inferior equipment to test those readings. Everything in their speakers are made in house no outsourcing.

Again thanks for the replies, anyone want a Denon 2106 last time i had it fixed it was $350.

Dono

Gix If you have pre amp outs. I suggest you pick up a Behringer Ep2500 and do the fan mod on it. You will never have a speaker that blows an amp again.

 

[highfigh]

Yea I know that ohms fluctuate while playing diff freq's. But doesn't a speaker at rest normally have a ohm reading in the very near vicinity of waht is stated in the specs. All the other speakers I have do. That is how I have set up amps for car audio for years without a problem. Maybe I'm doing something wrong the the MM but I havn't had a problem yet. I hope this makes sense I'm too pissed off to think.

On another note I brought my 10-15 yr. old Onkyo up just to make sure my brand spanking new speakers weren't fried as well and they work great. I beleive that the Onky has a lower power output, wanna say 75 per channel. But it is also a 4 ohm reciver and to tell the truth it sounds better on the Onkyo. Most likely that is because they are actually gettin more power. But there was more low ens extesnion and went louder with way less volume input. Yes I also know that you can't rely on the clock position of the Vloume knob\pot.

If the volume control is at the minimum setting, what the amp sees is the DC resistance because there's no frequency to make it vary. A couple of questions that I have are:

Do you have a cat or dog that likes to chew on things?

Is it possible that a single strand of wire is touching from positive to negative?

If the Denon actually sparked, it has problems. There's no way it should ever make sparks. However, if the speakers are really 8 Ohm nominal impedance, I think I would check with Focal to find out what the minimum impedance is. Even though an 8 Ohm speaker can have dips, they shouldn't go low enough to cause a problem unless something along the way causes it to be a problem. I have a customer who bought a Denon receiver and 5.1 Dynaudio speakers from me. These speakers are known to be a problem for many receivers and they have never caused a problem.

If you disconnect the Denon from hte speakers and turn it on, does it come out of protection? If it does, turn it on and measure the DC voltage on each channel's speaker terminals. It should be very close to 0VDC. If it's more than a couple of millivolts, it has a problem.

 

[highfigh]

This is what I was just trying to explain to my wife guese I should have been explaining it to myself. Whoops Which Is why they sounded better, got louder on my 4 ohm onkyo, right? Before I put my foot in my mouth again, or blow something else up.

Looks like sesnititvity is 92 db.

92dB is pretty sensitive. Many speakers do 86-89dB at 1W/1M and yours require quite a bit less power than those would.

 

[highfigh]

I do beleive it was the speakers for some reason, hate to diasagree with you cause I do respect your opinion on here.

And yes I have been into auido for the majority of my life and I still don't understand all that mumbo jumbo.

As far as fixing it I just got it fixed about 6 month's ago from me messing with some free speaks I got and I think I shorted out some wires with the power on DOH!

Way to go Don (that's me) you dumbass quit blowing up your **** you moron. But I do have a backup,the onkyo. I should have just got a new AVR with HDMI then but I didn't want to cut into my speaker budget too bad.

Can you geuss what my next thread will be? "What AVR should I get" It will be something like that. I just want to cry.

And i do listen to music ALL the time, it is my biggest passion, next to my family of course, but hey they can't sing worth a **** so........................

Before jumping on the "Denon is crap" wagon, think about what happened. You shorted the speaker wires with the power on about 6 months ago. That damaged the receiver and you had it repaired and after buying new speakers, it sparks again six months later. Then, you want to say the Denon is a POS, but it's possible that it still had an underlying problem from the first incident, but wasn't A) apparent, B) close enough that it dodn't seem to be a bad part, or C) what it would take to make the problem occur wasn't possible when it was at the place that repaired it.

 

[highfigh]

I never actualy tryed measure speaker DC vs AC resistance aka impedance, but i do pretty much know that they can be different in sense on several decades.

Even if you measure DC resistance around 3 ohms, it still doesn't meant it will not have more then 8 ohm when driven by your receiver.

Did OP actually measured resistance of whole speaker including crossover or took speaker apart and measured driver coils separately ?

Only really revealing way how to measure speaker impedance is to use frequency generator and measure current and voltage using AC signal with several different frequencies.
This is actually what speaker manufacturers or test labs do, and 4/6/8 ohm impedance specified by manufacturer is simple "average or approximated" value of measured impedance in full frequency spectrum they should be able provide.

If a speaker is checked using a multimeter, it can only measure the DC resistance- we agree on that. However, all it can measure through are the components that can pass DC voltage, which is everything except the capacitors or anything after them in the crossover. The meter is only seeing the woofer and the first pole of the low pass filter because the mid range has a bandpass filter (first pole is a cap) and the tweeter is on a high pass filter (first pole is a cap). Unless the crossover was wired incorrectly, there's very little that's actually involved in this test.

 

[gixxerific]

Before jumping on the "Denon is crap" wagon, think about what happened. You shorted the speaker wires with the power on about 6 months ago. That damaged the receiver and you had it repaired and after buying new speakers, it sparks again six months later. Then, you want to say the Denon is a POS, but it's possible that it still had an underlying problem from the first incident, but wasn't A) apparent, B) close enough that it didn't seem to be a bad part, or C) what it would take to make the problem occur wasn't possible when it was at the place that repaired it.

I never once said that Denon was a crappy company. Or that their products were ****. I know the first time was my fault all the way. I am very meticulous about this kind of stuff. But that time I was in a hurry and ****ed up. It was sparking a bit than, as well as that "it's burnt" smell. I should have bought another unit with the new codecs and patch cable interfaces that my 2106 lacked.

Before I got it fixed I was heavily looking at Denon, in fact they are the only site I have been to since this happened. I will look other alternatives as well.
My 2106 has performed flawlessly for abut 5 years until I let my guard down and killed it. But it was toasted pretty good the repair bill was around $350 - $400. I blew 6 of the outputs. If you wreck you're new car but get it fixed it just ain't a new anymore no matter how you look at it. I could have bought a decent recv'r brand new for what paid to get it fixed.