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carricter
10-10-2007, 07:16 PM
Very Basic: I have heard that a 4 ohm speaker can be a more difficult load for a power amp, but is there any sonic advantage to 16 ohm over 8 ohm or vise versa? What I am trying to determine is whether I sould look for 8 ohm components over 16 ohm components. Bottom line: Is there any advantage to one over the other?

Thank you, Don

scott fitlin
10-10-2007, 07:49 PM
Very Basic: I have heard that a 4 ohm speaker can be a more difficult load for a power amp, but is there any sonic advantage to 16 ohm over 8 ohm or vise versa? What I am trying to determine is whether I sould look for 8 ohm components over 16 ohm components. Bottom line: Is there any advantage to one over the other?

Thank you, Dondepends on your amp.

16 ohms is a walk in the park for any amp. But if you use a Crown, for example, the lower the net impedance, the more power the amp puts out. Conversely, a McIntosh which has autoformer coupled outputs, produces the same power at all impedances. So one 16 ohm woofer on a channel of a Mc will get full power capability, on a crown you get less at 16 ohms than 8 ohms.

Many Solid State amplifiers sound best at 8 to 4 ohms per channel. Tube amps certain ones, may be happier at 16 ohms to 8 ohms.

These days 4 ohms isnt a sweat either. 2 ohm might cause problems, but i doubt your going there.

Listen to the speakers your eyeing, and see what sounds best to you, IF you can!

8 ohm speakers are the norm, and have become standard, so, IF I had to say, I would recommend 8 ohm speakers.

Hope this helps.

Zilch
10-10-2007, 08:04 PM
What I am trying to determine is whether I sould look for 8 ohm components over 16 ohm components.I am sorry to inform you that many manufacturers (JBL included) played fast and loose with impedance ratings on some vintage drivers. Once you determine which drivers you want to use, you'll want make the appropriate inquiries here with respect to impedances.

scott fitlin
10-10-2007, 08:11 PM
Thats true. But, one still has to hear speakers of different impedance to make an informed decision.

16 ohm drivers usually have more winidngs on the VC, giving them a higher BL product. If your using an amp that produces the same power at all impedances, they might be worth a listen.


Conversely, if your using an amp that produces MORE power each time the impeadnce is halved, 16ohms down to 8ohms, you might not be satisfied with the output using 16ohm woofers.

As I said, these days 8ohms is standard, all amps function well at this impedance, and most amps can and will do 4 ohms no problem.

johnaec
10-11-2007, 06:52 AM
I am sorry to inform you that many manufacturers (JBL included) played fast and loose with impedance ratings on some vintage drivers.No kidding! My 4315A's are rated 8 ohm, but the impendance curve shows a significant portion closer to 2 ohms! :blink: See this: http://audioheritage.org/vbulletin/showpost.php?p=35238&postcount=1

John

carricter
10-11-2007, 09:44 AM
Hello Freinds: Thank you SO much for the information. After reading the replies I felt it would be helpful to give you a little more information on where I am at. I have two amps I use, but I intend to drive these with QuickSilver 8417 tube amps, beautiful sounding if you have never heard them, but they are best suited for high efficiency drivers / I am told they "fall apart" when asked to drive inefficient speakers. They do have a 4, 8 and 16 ohm terminal. The driver I am considering is am Altec 16 ohm 902A, which I am told "sounds fabulous." Also I am going to be using a 2405 tweeters and 416B woofers. I assume I could even mix the ohms if I run the drivers to the various terminals on the amps? But I would like to stick to all the same if possible. The main thing is that this stuff is hard to find and waiting for the right "Ohmage" to come along just makes it that much harder...

00Robin
10-11-2007, 04:54 PM
I'm going to mention again,and I do not know why,but when I used the BIG bad Luxman with all the little tiny buttons and frills and all,the Big Daddy Lux on my original 604's,a sound guy in Wyo. had to re-build that Lux three times from what he termed an impedance problem where the Luxman was too many watts for the speakers and they blew out the Lux.
Don't get me wrong,the sound was fantastic,but long term use that Lux was too much for the 604's. It would have seeemed to me that the speakers would have blown,but the sound guy said it goes back to the receiver.
THEN he put on a thing inside my speakers to prevent it. You guys must hate me,I have NO idea what it was,but all I know is they sounded like shit. And I made him take them off. Why would I want 604's that sound like shit? He argued and argued but i insisted and was mad he would ruin my sound. THEN I was freaked out it would NEVER sound good again.
So...a different guy said just get a receiver that isn't so big. Less wattage. He said the 604's want LOW watts not high.Duh on me. I tried three different ones and each one had a totally different sound. I was flabbergasted! I ended up with an old Pioneer SX-60. Now I KNOW there has got to be better receivers out there and I've tried some,but that little old Pioneer has given that "perfect" sound back to my speakers and the Lux,well,I took it to be repaired for the FOURTH time at $300 bucks a crack,those guys KNEW I would just pay and never know,but somehow,"mysteriously" the Big Luxman was "stolen" from the electronics shop.And I just never went back there.

But the lower my wattage and they never blew my receivers ever again. Now,someone must know what that was all about. The two books I got at the library did not cover ohms watts and impedance and impedance stoppers or whatever that awful thing was.
It just wanted lower watts and the sound was even bigger and more perfect. :blink::blah:

scott fitlin
10-11-2007, 05:10 PM
Umm, I think that if the speakers causaed damage to that reciever, and the fact that your sound repair guy said Impedance problem, the real problem was that the 604,s were too low an impedance for the Luxman, but that sounds strange, as they werent really Low Impedance speakers. However, the rated impedance of the 604 was a nominal 8ohms, and your amp sees the crossover network not the drivers directly, and I dont see why the Luxman couldnt deal with it.

By rebuild the Lux, I presume he had to replace blown output transistors, thats what blows in an amp when it is running at too low of an impedance. The fact that you say the Lux never sounded the same, and when you got a Pioneer reciever it sounded good again, indicates to me that your repairman may have used substitute parts instead of original manufacturers parts. Cheaper, alternative parts, instead of the manufacturers parts will change the sound of an amp, especially output transistors and capacitors. Unless the parts needed are NLA, I always insist on original manufacturers parts, ALWAYS.

Having more watts than the speakers were rated for doesnt damge an amp, it will blow speakers if you abuse them, and overdrive them, especially when speakers used to be more fragile than they are today. But, watts to the speaker doesnt blow the amplifier, too low an impedance can.

speakerdave
10-11-2007, 06:58 PM
. . . . And I just never went back there . . . .

That was right.

David

00Robin
10-11-2007, 07:55 PM
He said he had to completely re-build the sounding board each time. I think I just over paid an idiot alot of money. FOUR TIMES in five years. Oh no,the Lux always sounded the same. The guy added some impedance stopper to the Lux by way of inside the speakers. The thing still is in there unhooked up,I tore it off,it sounded terrible with it. See? THATS why I need to know this stuff. I'll send a photo of the thing he added that ruined the sound.
I also heard that that giant Lux was a re-builder,it was a late 70's HUGE one. But all that was 17 years ago now. I have the new 604's in there and they are puuuuuurfect. Me love them. My $100 Pawn shop find in the basement with all the paperwork,barely ever used by a dead piano player. :)

scott fitlin
10-11-2007, 08:51 PM
Sounding board? Amps have power supplies, input sections, pre driver stage, Last Voltage Amplifiers, and output stage. And some more things but it doesnt really matter.

What usually blows when the amp is running too low of an impedance are the output transistors.

The resistors he put into your spekaers were to keep the amp from dipping to too low an impedance, and as it altered the impedance and is more components for the signal to go through, it does affect sound quality. BUT, the 604 was an 8 ohm speaker, and should have been no problem for the Luxman to drive. Luxman was considered to be very good, I dont know why your did this. I do think the reapir shop you used might not have done the best work, or used the right parts.

8 ohms has been the standard impedance for a long time, amps from the 70,s and up do this load standing on their ear.

Back in th 50,s with many tube amps, proper impedance match was important, and 16 ohms was much more prevalent at that time. But modern SS audio uses 8 ohm loads as the standard.

Altec 8 ohm speakers were never known as difficult loads.

scott fitlin
10-11-2007, 08:56 PM
I have the new 604's in there and they are puuuuuurfect. Me love them. My $100 Pawn shop find in the basement with all the paperwork,barely ever used by a dead piano player. :)THAT is an outstanding find at that price, and you are lucky to have them.

You ever see what mint condition 604,s go for on ebay?

:thmbsup:

carricter
10-12-2007, 06:24 AM
It seems this string has gotten a little off track? see post #6 then post #7 ? Whatever, I have another question with regards to impedence: If a speaker is listed at 16 ohm by the manf. but reads closer to 8 ohms on a meter (as many of the altec drivers do), is it still correct to hook it up to the 16 ohm terminal on your amp?

speakerdave
10-12-2007, 06:48 AM
It seems this string has gotten a little off track? see post #6 then post #7 ? Whatever, I have another question with regards to impedence: If a speaker is listed at 16 ohm by the manf. but reads closer to 8 ohms on a meter (as many of the altec drivers do), is it still correct to hook it up to the 16 ohm terminal on your amp?

The direct current resistance of the wire, which you read on a multimeter, and impedance are different. The latter includes the DC resistance of the wire plus any inductive reactance in the voice coil, which develops under alternating current only because the magnetic field is being built with rising current and collapses again with falling current, and the resistive effects of air loading. Additionally, if you look at an impedance vs. frequency plot of a driver you will see that it only shows its nominal impedance in a rather small section. See the Transducer Information read-only forum for many examples. So, yes, hook it up to the 16 ohm tap.

David

Mr. Widget
10-12-2007, 10:15 AM
Dave, your skills as an educator are in evidence in that post. :D

Since I'm a visually oriented individual, I'll post an impedance plot of a speaker system... namely from some early work on Project May. This plot graphically shows how the impedance changes with frequency as Dave was discussing.

This system utilizes a pair of paralleled 8 ohm woofers, an 8 ohm mid, and an 8 ohm HF driver... with this knowledge one would assume this to be a 4 ohm system... that said, you can see from this plot that tweaks in the network change the actual impedance quite a bit and that the word "nominal" in the description of a system's impedance is rather significant.:)


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