Help with technical specifications

 

Bronze Member
Username: Derrtel

Post Number: 14
Registered: Dec-09
Hi,
I've been looking at several speakers lately, getting to know what's on the market before going to dealerships but I have problems understanding what is called nominal impedance (the ohms thing). Could someone explain me?
I know we're talking about an electrical resistance here, but I have no idea if this has to do with power input/output, power consumption, ...?
Should you "have" as much ohms as possible or as less as you can?
Thanks
(sorry for the bad english)
 

Silver Member
Username: Superjazzyjames

Post Number: 484
Registered: Oct-10
8 ohms is the standard impedence for home speakers. Most home amps (receivers, integrated amps and seperate power amps) are designed for 8 ohm speakers. Unless you want a very long high tech explanation by me or someone else, it's best to buy a pair of 8 ohm speakers. Frequency range and sensitivity/efficiency are the only really meaningful specs.
 

Silver Member
Username: Kbear

Canada

Post Number: 848
Registered: Dec-06
http://www.ecoustics.com/electronics/forum/home-audio/643339.html

This thread should help. The impedance (measured in Ohms) of a speaker can vary wildly, and it's never a constant. So when a company says 8 Ohms or 6 Ohms nominal, it generally means little.

Check out some Stereophile reviews, as they post speaker measurements. You can see just how much impedance varies, and their comments (while often tough to understand) are helpful. Also, the Symphony Sound article linked in the thread I provided above is a must read.
 

Bronze Member
Username: Derrtel

Post Number: 15
Registered: Dec-09
Thank you guys. I read the thread you linked and it was very helpful.
I think I get it now!
 

Platinum Member
Username: Nuck

Post Number: 15592
Registered: Dec-04
That's it?!? We don't get to redo it? Darn.
Let us know how you do, Derik?
 

Gold Member
Username: Magfan

USA

Post Number: 1895
Registered: Oct-07
Too easy?
 

Bronze Member
Username: Nency

Post Number: 99
Registered: May-09
Typical values for the nominal impedance of loudspeakers are 4, 8, 15 and 16 ohms (ohms are the standard unit of resistance). Four-ohm loudspeakers are normally battery-powered or found in automobiles, while 16-ohm loudspeakers are usually of the older, "valve" type, according to Hugh Robjohns, in the "Understanding Impedance Workshop.
 

Silver Member
Username: Superjazzyjames

Post Number: 701
Registered: Oct-10
I never heard of a 15 ohm speaker. 16 ohmers went out with the covered wagon. 4 ohms are standard for cars, 8 ohm are standard for home. There are a number of 6 ohm spkrs on the market for home use, but I'd recommend sticking with 8. Your amp probably won't like 6 ohms very much.
 

Gold Member
Username: Magfan

USA

Post Number: 1919
Registered: Oct-07
I'd love to see someone get my 4ohm panels in a car.
And, BTW, I've had 2 different models of 'em in the last 30yrs or so.
 

Silver Member
Username: Superjazzyjames

Post Number: 703
Registered: Oct-10
Again Leo, I'm talkin standards here. You and your system are the exception.
 

Silver Member
Username: Superjazzyjames

Post Number: 704
Registered: Oct-10
MOST speakers for home use are 8 ohms. SOME are 6 and a rare model or two are 4. MOST speakers for car use are 4 ohms. Anything that Leo has anywhere is the exception to the rule. He's got the only cd player that uses a needle, don't you Leo? Lol!
 

Gold Member
Username: Magfan

USA

Post Number: 1922
Registered: Oct-07
At least I don't find it necessary to keep a CD rewinder around.

Most? perhaps: that just means >50%.
The implication that 4 ohm speakers are unusual is just wrong.

However, the balance may have changed....and continue to favor 8ohm stuff, since most HT receivers are too junky to drive anything but.
That switch on the back of some HT receivers for low(er) impedance loads? Simply a concession by the designers that they make marginal power supplies.
 

Silver Member
Username: Superjazzyjames

Post Number: 710
Registered: Oct-10
ROTFL! That's a VHS tape rewinder! You're too much Leo!

Truth be known, yours are the only home speakers I've heard of that are 4 ohms in at least 20 years.
 

Silver Member
Username: Superjazzyjames

Post Number: 711
Registered: Oct-10
Didn't you notice I said VCR and TAPE rewinder?
 

Silver Member
Username: Superjazzyjames

Post Number: 714
Registered: Oct-10
Personally, I don't think there is anything wrong with 8 ohm speakers.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15632
Registered: May-04
.

?
 

Silver Member
Username: Superjazzyjames

Post Number: 719
Registered: Oct-10
Jan, in accessories I made a post regarding the "green power" feature in some of Monster's surge protectors. The model I have has 8 outlets. One can be used to shut 3 others off. When my receiver is in standby, the sub, dvd player and TV get no power at all. The other 4 are unswitched. I mentioned the vhs tape rewinder being plugged into one of these unswitched outlets.
 

Gold Member
Username: Magfan

USA

Post Number: 1926
Registered: Oct-07
VCR? TAPE? In that thread I thought you were having a retro/senior moment and ignored it. Don't you think a tape rewinder powered thru a power conditioner is a little....obsessive?
My crack was a reference to a CD player having a needle....
I keep a VCR to watch my Rocky and Bullwinkle tapes.

I haven't seen a tape rewinder in quite a while. I might have one in the box with my tape head demagnetizer and tape splicing block.

Just my opinion, but the 'green' outlets are just another solution in search of a problem.....
 

Silver Member
Username: Superjazzyjames

Post Number: 723
Registered: Oct-10
You're killing me Leo! Plugging the rewinder into surge protector is convenient. However, it did belong to my late in laws. So protecting it from surges is probably not a bad idea with regards to my wife and sentimental value she has attached to it. It's red and shaped like a sports car and the headlights light up when it's rewinding.

Rocky: Bullwinkle! Your foot!

Bullwinkle: Of course it's my foot Rocky, I've got another one just like it!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15635
Registered: May-04
.

???
 

Silver Member
Username: Superjazzyjames

Post Number: 724
Registered: Oct-10
Personally Leo, I like the green power and find it useful. There is no law saying you have to get one YET! I am trying to get such a law passed right now just for you! Just kidding!
 

Silver Member
Username: Superjazzyjames

Post Number: 730
Registered: Oct-10
My stereo cabinet is located near only one pair of outlets. I have the surge protector plugged into one outlet and a lamp in the other. There was only one outlet available for the rewinder, in the surge protector. So it gets protected. I'm sure everyone thinks I escaped from the funny farm by now. The truth is I haven't been there because I haven't been caught yet.
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 4527
Registered: Feb-07
"Truth be known, yours are the only home speakers I've heard of that are 4 ohms in at least 20 years."

http://totemacoustic.com/english/hi-fi/compact/mani-2-signature/specifications/
 

Silver Member
Username: Superjazzyjames

Post Number: 734
Registered: Oct-10
I didn't say there weren't others, David. I'm just indicating that 4 ohm in the home are not real common.
 

Silver Member
Username: Kbear

Canada

Post Number: 854
Registered: Dec-06
Dynaudio too.

If I had to ballpark it, I'd say 50% are 8 Ohms, 25% are 6 Ohms, and 25% are 4 Ohms. Maybe it's closer to 15% at 4 Ohms, I don't know, but I wouldn't say 4 Ohm speakers are rare. I've come across many.

And as discussed, nominal ratings tell about 1% of the story, so why put much stock into them? Paradigm Studio 20 is rated at 6 or 8 ohms, can't remember which, but what do you know? They actually dip below 4 ohms. So frankly, Paradigm's quoted nominal amount means nothing to me.
 

Silver Member
Username: Superjazzyjames

Post Number: 738
Registered: Oct-10
That's true and funny. Mirage states that omnis have a nominal impedence of 8 ohms and a minimum impedence of 4 ohm. Any guesses as to how accurate that minimum is? I like them, but I never believed that they never dipped below 4, especially at high volumes.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15638
Registered: May-04
.

?????!!!
 

Silver Member
Username: Superjazzyjames

Post Number: 747
Registered: Oct-10
Jan, what's up with all the ???? Are you okay tonight?
 

Platinum Member
Username: Nuck

Post Number: 15628
Registered: Dec-04
James, your posts are coming fast and stupid.
You have no idea how many varieties of speakers come as rated at 4 ohms, which is basically just a warning label?

Receiver salesmen must not advertise these much...
 

Silver Member
Username: Superjazzyjames

Post Number: 778
Registered: Oct-10
No they don't Nuck. Then again, the vast majority of reviews I've read on speakers in ALL price ranges were 8 ohms.
 

Gold Member
Username: Magfan

USA

Post Number: 1930
Registered: Oct-07
HT guys might not look 2x at 4ohm speakers. The guys that sell HT stuff may want 4ohm speakers to disappear....'an inconvenient truth', perhaps.
Real hi-fi stores have 'em all....and let the impedance fall where it may.
And yes, like most specs, treat it as advisory, not Biblical.

Thanks for the help, gentlemen.

I believe Jan is expressing a form of disbelief.
 

Silver Member
Username: Superjazzyjames

Post Number: 798
Registered: Oct-10
When I read speaker reviews, they are always writen by serious audiophiles, NOT HT guys. Hardly ever is 4 ohm speaker mentioned and 6 occasionally, but since impedence is only a nominal or advisory spec anyway, why would it matter?
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 4532
Registered: Feb-07
It's probably rather meaningless unless you look at the impedance + phase chart for the speaker.
 

Silver Member
Username: Superjazzyjames

Post Number: 806
Registered: Oct-10
Even with the phase chart, how much real meaning is there?
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 4534
Registered: Feb-07
A lot more useful than just the nominal impedance. It lets me see if the speaker is going to play nice with my tube amp.
 

Silver Member
Username: Superjazzyjames

Post Number: 807
Registered: Oct-10
How many speakers are there on the market that will play nice with a tube amp these days?
 

Gold Member
Username: Magfan

USA

Post Number: 1932
Registered: Oct-07
Between phase and impedance, a judgement, preliminary as it is, about a speakers ability to 'play well' with tube is possible.

A big impedance dip at the same frequency as a huge bump/dip in phase is a red-flag situation.

Super,
Please look up Power Factor for a better look at this info
Also, take a look for 'Smith Chart', a way to represent BOTH phase and impedance with a single line. This display to many is very readable and has all the relevant info about phase/impedance in one package. No double lines.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15648
Registered: May-04
.

"How many speakers are there on the market that will play nice with a tube amp these days?"

"Even with the phase chart, how much real meaning is there?"




The vacuum tube market is alive and thriving - especially low wattage, single ended tube amps sold exclusively through the internet. They may not be worrying Pioneer but they are an active market keeping dozens of companies in business. Whether a speaker plays well with a tube amp isn't even the point of impedance and phase. Most tube amps are transformer coupled and will match to the nominal impedance of virtually any speaker on the market. But nominal impedance is not the issue, a tube amp's high output impedance will respond to the impedance swing of the speaker's reactive nature resulting in bloated lows or thinned lows, screaching highs or rolled highs, peaked mids or laid back mids or everything as it should be. Knowing the impedance swing vs the nominal impedance tells the user which speakers are suitable for their amplifier. Knowing the phase angle of the reactive component will tell the user whether the speaker requires high current or high voltage - an important consideration when using a tube amp or a low powered (not high current delivery) solid state amp.

In the end, a speaker that is easy to drive is desirable no matter whether the speaker is attached to a tube or a solid state amp. A speaker that does not require a massive power supply and high current delivery will play well with any amplifier. That's "how many" speakers are designed to operate with tube amps - any that are meant to play well with any amplifier, tube or not. If you have a low wattage amplifier or a low current amplifier, say, a budget HT receiver, you want a speaker that can play well with a tube amp.

James, what you claim to have read doesn't seem to be in synch with the real world. I would say you are once again covering your @ss after making a less than factual statement. Four Ohm speakers have been around for ages - The Small Advent designed in the late 1960's was a "four Ohm" speaker as were many of the earlier AR and KHL models all of which had "best selling" models in the 1950-70's. Sixteen Ohm speakers were not that uncommon until solid state arrived and the technology preferred eight Ohm loads. I have a pair of fifteen Ohm speakers which I have used for many years, they were designed in 1976 - twenty years after the introduction of transistors - and they are widely recognized as a model for speakers to follow. Four Ohm speakers are common. Why not just let it go at that? Stop arguing everything you say when a considerable amount of what you say is incorrect.





.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 15649
Registered: May-04
.

"When I read speaker reviews, they are always writen by serious audiophiles, NOT HT guys."


http://www.ultimateavmag.com/

http://www.avguide.com/channel/the-perfect-vision

http://www.audioholics.com/

http://www.widescreenreview.com/

http://www.electronichouse.com/


C'mon, James, just because you don't know about it, that doesn't mean it doesn't exist. Stop arguing everything.


.
 

Silver Member
Username: Superjazzyjames

Post Number: 813
Registered: Oct-10
Jan, I asked DAVID a simple question, not you. Otherwise, yes I have read many speaker reviews by serious audiophiles and 4 ohm speakers are rarely mentioned in those reviews.

I really don't care about Advent speakers from the 60s. What's that got to do with here and now? Nothing!
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 4535
Registered: Feb-07
"How many speakers are there on the market that will play nice with a tube amp these days?"

There's lots James. I have 2 pairs at home that are exceedingly tube friendly. I look out for what Leo mentions:

"A big impedance dip at the same frequency as a huge bump/dip in phase is a red-flag situation."
 

Silver Member
Username: Superjazzyjames

Post Number: 815
Registered: Oct-10
Thank you David. The last time I had tubes was in the 80s. I had very old pair of Scott integrated mono amps, 35 watts each. Sometimes wish I still had them. My grandfather gave them to me. I remember the preamp tubes were either 12AU7 or 12AX7 and the power supply was a 5U4GB. I don't remember the outputs though.
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