4ohm speakers & 8ohm amps

crouse

Is there any rule of thumb for deciding if an amp that is only rated into 8ohms will drive 4ohm speakers? I have a Music Hall a15.2 rated 75wpc into 8ohms. The manual gives no specs into 4ohms but a few speakers I am interested in are rated as either 4ohms or 6ohms and I live in an audio desert with no store nearby to demo them.
Thanks

dudeinaroom

If it is only rated for for a minimum 8 ohm load, you will burn it up trying to run 4 ohm speakers. I'd get a hold of Music Hall and see if it can handle a 4 ohm load. You could get some 4 ohm dummy load resistors to run in series with the 4 ohm speakers to bring them up to 8, but you might loose some sound quality.

coolsax

I have one and it can Handle 4ohm loads per Roy Hall himself, haven't tested it as I don't have any 4ohm speakers currently, but I emailed him this question when it came out b/c I was still trying to decide on speakers and he confirmed it can handle 4ohm loads.

crouse

Thanks. Good to know.

nhhiep

i wouldn't do that. think about it, there is a reason why they didn't put it in the spec. most amps can handle 4ohms. strange to see one doesn't.

tonyb

That amp is on the light side for LSI's if thats the purpose. It won't have the balls once the volume goes up and that spells trouble. Look for something with some good power if your mindset is for the LSI line.

coolsax

Also.. Stereophile had a short review of the amp as well (vol 33 #12)and it was tested with Dynaudio Xcite 12 which are 4ohm nominal speakers as well. It also made a C Rating on Stereophile's recommended components list for 2012 for integrated amps.

Drenis

nhhiep wrote: »

i wouldn't do that. think about it, there is a reason why they didn't put it in the spec. most amps can handle 4ohms. strange to see one doesn't.

That's a load of BS. Some manufacturers have put power (wattage) specs for example that aren't stated as either RMS values or dynamic peak power. Just a value @ whatever ohm rating.

I also know some Carver amps didn't publish 4-ohm specs but are stable and comfortable driving them. My point is, do your research on a piece!

nhhiep

from a marketing point of view, I don't see how it hurts them by not listing that critical info if the amp is designed to handle it. will it run 4 ohms? probably yes. But did they engineer it with 4 ohms in mind? I doubt that.

yes, we push cars, speakers, amps, etc...over the specs all the time, but is it recommended?

mantis

nhhiep wrote: »

i wouldn't do that. think about it, there is a reason why they didn't put it in the spec. most amps can handle 4ohms. strange to see one doesn't.

IF an amp can HANDLE 4 ohms doesn't mean you should. Here's the deal , Dynamic range this is what suffers when you run speakers with amps that can hold 4 ohms but run out of current and cap storage power just to stabilize the load.

The best 4 ohm load amps are the ones the double their power from 8 ohm to 4 ohm. Not many do that but they are the ones that don't run out of current or storage power when driving such loads. Some very good amps will greatly increase their power from 8 to 4 and are pretty good to use. So if an amp has 200 watts and goes to lets say 300 or more , then a 4 ohm load speaker under reference levels will perform well but has a slight risk of running out of juice IF one decides to run at reference. Now in a home theater situation , if your using 4 ohm load speakers and have an amp that is 200 watts at 8 and 330 at 4 , you can use this amp for reference as all channels don't always fire at the same time peak to peak and IF they do , this amp will be ok. A better amp would perform better like one thats 200 watts at 8 ohms and 400 or very close to it at 4 ohms. This amp will perform flawless under all conditions.

Remember picking a amp for 4 ohm load speakers , you need to know how you plan on using said amp. If your a volume junkie , buy the most powerful amp you can , if you listen at less then reference levels most of the time then you have a world of amps out there that will easily suit your needs. Remember it's all about use.

Last note , most if not just about all receivers don't do well or not at all with 4 ohm load speakers. Companies like Onkyo / Integra claim to support 4 ohm loads but at a price. They lose dynamics and don't perform 100% under these conditions but don't fail under extreme loads. So the question is do you want to have 4 ohm load speakers and not be able to drive them correctly?

All amps , Integrated , receivers that can support 4 ohm loads usually put it in it's spec's. If it's not listed , I suggest moving on. I wouldn't waste my time researching it. I would shop for proven 4 ohm load Intergraded units that do a great job at it. That is worth the time and research to find out.

mhardy6647

Transformer-coupled amplifiers are perfectly happy with 4 ohm loads. Just sayin'...

crouse

Thanks for all the replies. Food for thought.

crouse

Well, I also e-mailed Roy Hall and he said the a15.2 will have no problem with 4ohm loads, so that increases my choices if I choose to upgrade. BTW, I really like the sound of the a15.2. It is much smoother sounding than the Denon AVR I had been using. Only one complaint: one of the blue LED source indicator lights went out after just a couple of weeks of use. Mr. Hall said I could not replace it myself and the repair center is about 1000 miles away. Grrrrrr