Why 4 Ohm Loads Stress Your Amplifier

Yup, there's more than a few amps out there like my SAE 2600 that could double as a welder.
 
I've read some of this and don't really understand much. So, is it OK for my Marantz 2252 to be hooked up with Klipsch KG4's. Or , a 2235 with HPM-100's and Sansui 1200 together? Both would be 4 Ohms. I don't use more than half volume or less as both set ups are in medium size rooms.
 
question: I have a Mac 2105 amp that has speaker hookups for 4, 8 and 16 ohms. thinking of buying a pair of ML Theos which are rated at 4 ohms. wondering if this setup would run hot and if extra cooling would be needed? Good matchup / not good matchup. Of course the sales guy says no problem. appreciate any feedback. didn't think much about it until i saw the discussion on the 4 ohm load running hot. thanks!
 
The amp is rated for a 4 ohm load so you should be fine.

My opinion is that so long as an amp says it can drive 4 ohms loads then it doesn't really stress the amp and no extra cooling should be needed given the manufacturer designed the amp to handle 4 ohm loads and if extra cooling was needed it would have been built into the amp by the manufacturer.
 
So, am I going to have a problem driving my a/d/s m-15 speakers with my new to me Yamaha ca 2010. The owners manual says 8 or 16 ohm speakers?
 
Yes if your ADS speakers are 4 ohm and your receiver says only 8 and 16 ohm speakers then yes that would be a problem.
 
The problem with fans is that if they are going to move air, they are probably going to make noise, so then, unless your amp is not in the same room as the speakers, its probable that you will turn the volume up. Probably you'll get ample cooling, but you are raising the noise floor.

I have 3 PC cooling fans on my HT amp. Its 135x7 watts and gets really hot. With the fans its cool all the time. I can't hear the fans at all.

One blows it across, one pulls it from the top and the third vents out the back of the Cabinet.

I bought them from
http://www.coolerguys.com/ho.html
 
fans and dirt

For commercial sound installations (mostly bars) I was a big fan of cooling fans for a decade or two. Got away from them simply because they move dust and dirt into switches and even connectors. In the end I decided that for reliability - better to relocate the amps and put up with longer speaker wires and interconnects. Of course in Pro sound these aren't solid sliver/platinum five thousand dollar items.
Gotta say - most HT furniture is in terms of cooling really badly designed. Compound this by stuffing the cabinet full of equipment - inevitable premature failure is to be anticipated.
For home use - almost every single amp I've ever really liked runs at least warm ( Exposure integrated is the exception - how the heck do they get great sound without heat ?) - with some effort on the part of old muscles - amps get put on the top of the cabinets. Space and convection works with a properly designed amp.
And to go back to the start of this thread - haven't owned a amp that won't drive 4 ohm loads for a LONG time.
 
Thanks for starting this thread 240! Lots of great info. I was one of the ppl that started a previous thread asking if I will damage my Sansui 8700db (rated for 8ohm) with my Advent Laureates rated at 6-8ohm. From what Ive gathered here the short answer is yes it could damage it- but- it should be fine at moderate volumes with good ventilation. I have a box fan behind the receiver and the heat sinks are barely warm. Does this sound reasonable?
 
Odd -- I would have guessed that there was no more chance of your damaging your amp with your speakers than with any non crackpot speaker. Impedances are only averages -- the impedance varies significantly with frequency and so a company that says 6-8 ohms probably is simply being pickier than another company with a speaker with essentially the same impedance curve which might simplify things by calling it 8 ohms.
And amp that can't run 6 ohm speakers probably shouldn't be released on the mass market -- even a 4 ohm pair should be fine as long as you don't headbang with it and ignore all the warning signs.
It's when you parallel two pairs of 4 ohm speakers that things get dicey, but that's because the overall impedance of the two pairs is 2 ohms, and that is the average, so at the lowest impedance its probably close to a dead short.
 
This topic is near and dear to my heart now...I was running Apogee Centaur speakers (5 ohm nominal, 3 ohm minimum) with an AVR rated for 6-8 ohms. No problems for months, until last night, when I heard some clipping at moderately-loud volume. Getting a Crown PSA-2 tomorrow! That should take care of the power issue...hopefully it is still plenty musical and just brute force.
 
I have had issues with this with my thiel speakers, I originally auditioned with some uber VTL amp, when I got them home they sounded okay with a Musical Fidelity A3CR, I tried 5 amps before I found one that sounded right, it was one that doubled into 4 ohms, it has no problem with the 3 ohm dip that the speakers have, everything sound way more balanced when the amp is up to the job of demanding speakers
 
A well designed amp should not have any problems with 4 ohm nominal impedance speakers IMO. Or at least they didn't in the 70's. Back then even a basic 12 - 25 wpc amp from the likes of Pioneer, Marantz, Realistic and others did a great job with 2 pair or 8 ohm, or one pair of 4 ohm speakers.

I was just listening to my 35 year old 10 wpc Realistic STA-7 receiver with the 4 ohm speakers I've been using for many years and have never had an issue that more current would correct. For the SPL's I normally listen to (80 - 90 db's) there is still enough power to effectively drive a 4 ohm load, even with low sensitivity speakers at -3 db's. Of course it's not as transparent as the better amps, But the bass response and the SPL's I would expect are way better then they have any right to be.

The reason 4 ohm loads stress Some Newer Receivers/Amps is because in order to market them with higher power levels (say 70 wpc vs 50 wpc at 8 ohms), is they must limit the amps current output that they would try to deliver when a 4 ohms load is present. Far worse then just running out of current and clipping, this can cause an amp to become unstable and oscillate, Frying the connected speakers in short order even at power levels far below clipping.

The cheapest way to limit current is simply to restrict the speakers impedance by using only 6 ohm or higher rated speakers, and sometimes by installing a cheater switch, Which reduces the amps output to where it should have been to begin with.

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The back of many amps and receivers tells us all we need to know about minimum speaker impedance. If not check the owners manual or check on line. Just because an amp is rated at 8 ohms it does not mean it won't safely drive a 4 ohm load. With stereo amps/receivers (not 5.1/7.1 AVR's), If it has an A + B speaker option for speakers, Like my 10 wpc Realistic stereo receiver has, Then it is likely stable into a 4 ohm load. If you keep the volume at -3 db's (1/2 power) then you should be fine if the amp is operating correctly.
 
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Hey guys!
Im wondering if something like sansui 6060 or marantz 2238b would have any troubles running infinity reference 50 speakers?
Here's the link:
http://audio-database.com/INFINITY/speaker/reference50-e.html
I got them for free and now Im looking for a receiver and a turntable.

The Infinity's are rated nominal 6 Ohm, max 150 W.

Your Sansui 6060 receiver seems to be rated 40 wpc at 8 Ohm:
http://www.radiomuseum.org/r/sansui_stereo_receiver_6060.html

The Marantz is rated at 38 wpc at 8 Ohm, and 48 wpc at 4 Ohm:
http://www.classic-audio.com/marantz/2238b.html

IMO, both are underpowered to really drive the Infinity's to their potential. Since Marantz is rated to 4 Ohm, it is probably a better choice. Just do not crank up the volume, or you will damage the receiver, the speakers or both...
 
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