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Dustin_Broke
07-01-2011, 01:54 PM
When you have a receiver like some of the Kenwoods that have a ohms switch what does it actualy do? Like if you have 4 ohms speakers and you set it to less than 8 ohms what's the difference from having it less than 8 ohms or 8 ohms or more? I heard some people say that it's best to keep it to 8 ohms or more even if you have 4 ohms speakers but is that true? They said something about clipping could happen but I don't know what that means. I just wonder what does the switch actual do when you change from less than 8 ohms or 8 ohms or more.

markw
07-01-2011, 02:28 PM
AFAICT, when set to four ohms it limits the power to the speakers to help prevent triggering the protection circuits (or worse) when driven hard.

...this verifies the answers you're getting for this exact same question on this thread (http://www.audiokarma.org/forums/showthread.php?t=378862) at AudioKarma where, as usual, you're arguing with the answers, ignoring any advice, and the instructions in the manual.

next....

Dustin_Broke
07-01-2011, 03:47 PM
I will post this again as I did on the other forums and people here should know me more since I been here for many years.


I posted same topic here and on other forums since I want to see whats the most common answer I get and choose that one. Everyone says differently so I need to get to see which is the common one since that is probley the most right answer.

mlsstl
07-01-2011, 04:51 PM
I found a manual for a Kenwood 104AR. It says the switch is there for safety reasons - to prevent the unit from overheating. The exact wording is "Caution: to prevent fire or damage requiring service, set the impedance selector as described below." (A pictorial then shows the options.)

This indicates the voltage limiting answer you received is correct.

Here's the technical side. Let's say you have a 75 watt per channel (8 ohms) receiver. That will have a power supply rail voltage of about 25 volts and the speakers will draw a shade over 3 amps. (Easily calculated per Ohm's law.)

However, solid state amps are current sources. If you hook up 4 ohm speakers instead of 8, the amp will try to still deliver 25 volts, but now at 6 amps. In other words, the amp will try to put out 150 watts per channel instead of 75.

That means the amp has to handle double the power and will run hotter. This increases the chance of damaging the amp, or even a fire.

Hence, to meet safety standards, the 4 ohm switch reduces the max voltage and keeps the power output at a safe level for the amp. The amp will still work when 4 ohm speakers are used with the switch at 8 ohms, but you increase the chance of problems.

I'm assuming other Kenwood models with this switch are designed similarly.

Smokey
07-01-2011, 11:28 PM
I found a manual for a Kenwood 104AR. It says the switch is there for safety reasons - to prevent the unit from overheating. The exact wording is "Caution: to prevent fire or damage requiring service, set the impedance selector as described below." (A pictorial then shows the options.)

This indicates the voltage limiting answer you received is correct.

Here's the technical side. Let's say you have a 75 watt per channel (8 ohms) receiver. That will have a power supply rail voltage of about 25 volts and the speakers will draw a shade over 3 amps. (Easily calculated per Ohm's law.)

However, solid state amps are current sources. If you hook up 4 ohm speakers instead of 8, the amp will try to still deliver 25 volts, but now at 6 amps. In other words, the amp will try to put out 150 watts per channel instead of 75.

That means the amp has to handle double the power and will run hotter. This increases the chance of damaging the amp, or even a fire.

Hence, to meet safety standards, the 4 ohm switch reduces the max voltage and keeps the power output at a safe level for the amp. The amp will still work when 4 ohm speakers are used with the switch at 8 ohms, but you increase the chance of problems.

I'm assuming other Kenwood models with this switch are designed similarly.

Excellent post :thumbsup:

BallinWithNash
07-02-2011, 03:01 AM
I found a manual for a Kenwood 104AR. It says the switch is there for safety reasons - to prevent the unit from overheating. The exact wording is "Caution: to prevent fire or damage requiring service, set the impedance selector as described below." (A pictorial then shows the options.)

This indicates the voltage limiting answer you received is correct.

Here's the technical side. Let's say you have a 75 watt per channel (8 ohms) receiver. That will have a power supply rail voltage of about 25 volts and the speakers will draw a shade over 3 amps. (Easily calculated per Ohm's law.)

However, solid state amps are current sources. If you hook up 4 ohm speakers instead of 8, the amp will try to still deliver 25 volts, but now at 6 amps. In other words, the amp will try to put out 150 watts per channel instead of 75.

That means the amp has to handle double the power and will run hotter. This increases the chance of damaging the amp, or even a fire.

Hence, to meet safety standards, the 4 ohm switch reduces the max voltage and keeps the power output at a safe level for the amp. The amp will still work when 4 ohm speakers are used with the switch at 8 ohms, but you increase the chance of problems.

I'm assuming other Kenwood models with this switch are designed similarly.

Great example!!!! and what he is saying is ..... FOLLOW THE MANUAL!!!!

mlsstl
07-02-2011, 05:58 AM
One more comment. You'll probably be fine with the switch at the 8 ohm setting with 4 ohm speakers if you're playing music at background or softer medium volume levels. The problem arises when you start to turn up the volume, particularly if the speakers are inefficient.

The catch is one person's "loud" may be another's "medium" volume. Without test gear, you won't know when you've crossed the line and the amp is operating in unsafe territory. The easiest solution is to simply follow the manufacturer's instructions.

Dustin_Broke
07-02-2011, 08:40 AM
One more comment. You'll probably be fine with the switch at the 8 ohm setting with 4 ohm speakers if you're playing music at background or softer medium volume levels. The problem arises when you start to turn up the volume, particularly if the speakers are inefficient.

The catch is one person's "loud" may be another's "medium" volume. Without test gear, you won't know when you've crossed the line and the amp is operating in unsafe territory. The easiest solution is to simply follow the manufacturer's instructions.Thank you very much. I can say both of your answers makes the most sense. I like when you showed the tech spec examples so I can see it more in details.

Btw so it looks like if I set it to 8 ohms or more it's kinda like a receiver that doesn't have a switch and is rated 8-16 ohms. Since I remember people were saying the same thing for receivers that is 8-16 ohms and about not having it too loud since it will get really hot.

Also I do agree that everyone hears differently and some people might say this is loud but for the other person it's medium volume.

I guess I' am lucky that this receiver has the switch since then I don't have to worry about having it too loud. If I used other receivers that don't have the switch and that is rated 8-16 ohms then I will have to watch and make sure I don't have it too loud so I don't over heat it.

Dustin_Broke
07-02-2011, 08:53 AM
Btw I did use to have a Sony receiver that doesn't have the swtich and was made for 8-16 ohms and I remember having my music loud for like 10 min and the receiver did get very hot that if I kept my hand for a sec on it it will burn but for somereason nothin happened to it and still works fine. I wonder why the protection mode didn't go on. Maybe it wasn't that hot that the protection mode kicked in. But eather way I assume that it wasn't good that I had it loud for that long but all I know is that nothin happened to the receiver and after I turn it back to normal volume it cooled off and was in normal temp. I did also tested another two other receivers one was another Sony and one was a Kenwood that doesn't have the switch and both were rated the same and both did exactly the same thing and protection mode didn't even go on but got really hot.


I just thought this was interesting experiment. I did this test since I know I had 7 days to return it to Goodwill since they will take back anything if it's before 7 days. They said if anything stops working they can just recycle the product.



Btw how loud I had it was loud enough that almost the SK3 lamp started to light up since if I had it too loud the lamp will blow and no sound will come out of the speakers. This is like a fuse to protect the speakers. I play alot of bass tester songs so it's easy to make the lamp start to light when the bass hits. You will be supprised that even I set the bass and treble to flat the bass hits really hard than normal music since these are bass tester songs but all I can say is that just having it loud but not that loud will make the SK3 lamp start to light up.

bobsticks
07-02-2011, 09:34 AM
AFAICT, when set to four ohms it limits the power to the speakers to help prevent triggering the protection circuits (or worse) when driven hard.

...this verifies the answers you're getting for this exact same question on this thread (http://www.audiokarma.org/forums/showthread.php?t=378862) at AudioKarma where, as usual, you're arguing with the answers, ignoring any advice, and the instructions in the manual.

next....

I laughed out loud, I spit coffee, I experienced the entire range of human emotions...nice post...

...and great advice from mlsstl...Greenies for both you gentlemen...

mlsstl
07-02-2011, 12:17 PM
Btw I did use to have a Sony receiver that doesn't have the swtich and was made for 8-16 ohms and I remember having my music loud for like 10 min and the receiver did get very hot that if I kept my hand for a sec on it it will burn...
You can't tell whether an piece of electronic gear is truly overheating or not by touching it. Most people think something is too hot to touch longer than briefly when it is around 120 degrees Farhenheit or so.

A typical transistor on an amplifier is often rated to operate to 125 or 150 degrees Celcius or even higher. That's 250 to 300 degrees Fahrenheit! Now that's dissipated through the heat sink which will run at a somewhat lower temp, but that's still way to hot to touch even though the temps are still OK for the unit.

That's why you can't tell much without proper test equipment.

My recommendation is to stop worrying about it. Set the switch to the proper setting and listen to some music!

Dustin_Broke
07-02-2011, 04:32 PM
So I guess that means pretty much any kind of receiver I get and use on my JBL Control 1 speakers will work fine just get kinda hot. Since it seems like you are saying that what I think it hot isn't that hot actualy.

I did sell all of the receivers I had and actualy got more money than I paid but I the Kenwood receiver that has the switch hasen't came to me yet it's still in a shipping process. But I did find a Pioneer SX-255R stereo receiver at Goodwill and this receiver is also 8-16 ohms but it seem like any receivers I get that is for 8-16 ohms works fine with my JBL Control 1 speakers. Since the receiver just gets hot but apparently not that hot that it's overheating. Basicly every receiver I have tested worked fine using just one pair of 4 ohms speakers on a 8 ohms receiver. Only thing is that any receivers that can handle 4 ohms doesn't get hot at all and the ones that is not for 4 ohms gets hot. But other than that it seems like they all work.

This is very interesting since I thought that if the receiver says 8-16 ohms speakers then if I had anything lower than 8 ohms will fry the receiver when it up loud. But apparently that was not true since I had my music loud and the receiver only gets hot but not overheating looks like.


Is it possible that since my JBL Control 1 speakers are compact speakers they don't use that much power even it's 4 ohms?

mlsstl
07-02-2011, 05:01 PM
You've got a lot of different variables at work. Your speakers are rated at 87 dB efficiency. That's on the medium to medium-low side, which means they need a fair amount of power to play loud. Since they are small speakers, the situation can be exacerbated by the temptation to crank the bass control up. That can add to overheating issues.

If you use an amp rated only for an 8 ohm load with 4 ohm speakers, the long term effect will probably be to shorten the lifespan of the amp. It'll break sooner rather than later - heat does that to electronics. The problem is there is no way to know for sure when or if it will happen. Ultimately, the wiser thing to do is find an amp designed to work with your speakers instead of counting on luck to make things work.

Dustin_Broke
07-02-2011, 05:43 PM
Well on the service manual it says that the speakers have 90 db sensitivity but I wonder why on the spec sheet it says they are 87 db. I wonder which is true. I remember when I talked to JBL they said the original Control 1 speakers are 90 db on the sensitivity but for somereason on the spec sheet it says 87 db. But if the speakers are 90 db is that good? But eatherway there is no way to prevent the receiver from damage if the receiver is rated 8-16 ohms? Also are you sure any heat will shorten the lifespan? Meaning even if it doesn't get super hot it will still shorten it? If so probley the Kenwood that is coming soon will be best since that is the one that has the switch so I can select it to less than 8 ohms.

Dustin_Broke
07-02-2011, 05:51 PM
Btw does it help at all by cleaning all of the dust in the receiver like using a vacume and using air cans to blow all of the dust? I did do that after I got the Pioneer receiver since I thought there was alot of dust and there was so I did clean it.

But maybe if 4 ohms speakers are that dangerous for 8-16 ohms speakers I really might have no choice but to get a 8 ohms speakers then forsure any receiver will work fine but I hope I can some how make the Pioneer SX-255R receiver work with my 4 ohms speakers since I know that the Pioneer receiver has more power and sounds more clear than the older Kenwood that has the switch. I remember using a Kenwood receiver that has a switch and it wasn't as clear as the Pioneer one. I use to have a Pioneer VSX-405 receiver years agao but since it was old it stoped working for somereason.

mlsstl
07-02-2011, 06:52 PM
The 87 vs 90 dB speaker sensitivity may be due to differences in measurement. The 87 dB may be at 1 watt of power and the 90 dB might be measured at 2.83 volts (which is 1 watt at 8 ohms but 2 watts at 4 ohms.) There are all kinds of games one can play with specs.

As for the heat thing, there is a relationship. Think of your car - the harder you drive it the faster tires, brakes and other parts wear out. That doesn't mean they break or wear out on a specific timetable, but it is still tougher on them.

And finally, yes keeping dust off your equipment is good for it.

pixelthis
07-04-2011, 02:06 PM
ANY RECEIVER with a 4/8 ohm switch is pretty old, don't see
that much anymore, receivers have other ways of handling that these days, or so I HAVE HEARD.:1:

BallinWithNash
07-04-2011, 09:12 PM
Dude how many times are you going to rephrase the same question? It's not that hard to figure out ... If you are going to play your ****ty speakers extremely loud switch it down to the lower ohm's but if you are going to listen to them at a moderate to quite level for shorter periods of time leave it at 8.
You should stop buying receivers and buy some decent speakers...
http://cgi.ebay.com/Paradigm-Titan-Monitor-V-6-Bookshelf-Speakers-Pre-Owned-/250823174117?pt=Speakers_Subwoofers&hash=item3a6639e7e5#ht_677wt_905
Or I really like the JBL 4406 very vocal!
http://cgi.ebay.com/JBL-Professional-Series-4406-Studio-Monitors-phenomenal-/260812658801?pt=Speakers_Subwoofers&hash=item3cb9a55871#ht_13799wt_1202

Dustin_Broke
07-05-2011, 09:52 AM
Yesterday I got a new pair of the JBL Control 1Xtreme which is the same speakers as I have now but it's 8 ohms instead of 4 ohms so now I will be happy and no more ohms problems. :thumbsup:


The Control 1 speakers I have now is in auction on Ebay and hopefuly I can get some money out of it.


The Control 1Xtreme is coming in 3 days so it's not going to be that long.

markw
07-05-2011, 10:33 AM
Yesterday I got a new pair of the JBL Control 1Xtreme which is the same speakers as I have now but it's 8 ohms instead of 4 ohms so now I will be happy and no more ohms problems. :thumbsup:


The Control 1 speakers I have now is in auction on Ebay and hopefuly I can get some money out of it.


The Control 1Xtreme is coming in 3 days so it's not going to be that long.You said you were going to do in post 21 of this thread (http://forums.audioreview.com/showthread.php?t=36740) you started two weeks ago on this very same subject.

Thanks for proving me right

PS. They still won't have any bass though...

Dustin_Broke
07-05-2011, 10:35 AM
Well that one was a used one and I did return it to the seller but now I got a new one so that's even better but it did cost more. I basicly refused the package for the used one so I did get a refund on it.

markw
07-05-2011, 10:57 AM
Well that one was a used one and I did return it to the seller but now I got a new one so that's even better but it did cost more. I basicly refused the package for the used one so I did get a refund on it.You get buyers remorse, even after the subject was hashed out here two weeks ago, and you go stick some other poor schlep with the financal consequences.

I'm sure people love doing business with you. :rolleyes:

SlumpBuster
07-05-2011, 05:26 PM
You get buyers remorse, even after the subject was hashed out here two weeks ago, and you go stick some other poor schlep with the financal consequences.

I'm sure people love doing business with you. :rolleyes:

That's the same observation I made a couple months ago, Mark. He called me mean and decided to ignore me.
http://forums.audioreview.com/showthread.php?t=36107


Hey Spanky, whatever happened to those b1tchin' Cakewalk monitors?!?

BallinWithNash
07-08-2011, 02:34 AM
That's the same observation I made a couple months ago, Mark. He called me mean and decided to ignore me.
http://forums.audioreview.com/showthread.php?t=36107


Hey Spanky, whatever happened to those b1tchin' Cakewalk monitors?!?

Bahahaha that kid never listens to anybody I cant count the number of times you guys said sony sucks and he wouldn't drop it .... "Trying to explain something to this kid is like trying to dig a hole in dry sand with a teaspoon in a stiff wind." MarkW lmao!!!!!!