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Austin Bob
Austin Bob's picture
Last seen: 6 years 2 weeks ago
Joined: Sep 11 2012 - 8:10am
Amplifier Power Output - 8 Ohm/4 Ohm Ratio?


I orginally posted some questions about building out a modest system and was almost ready to go with the following:

1. Music Hall 15.2 Integrated Amp

2. OPPO BDP 93 (or if I decided to go over budget, the BDP 95)

3.  PSB Image B6's

Because I have heard so many reviewers rave about the Mag MMGs, I decided to take another look at them (after I factored in the cost of decent speaker stands for the BX2's, the MMGs are in my price range - and the relative footprint is not much different to accommodate my living room). I was reading the FAQs on Magnepan's website, I found the following excerpt regarding amplifiers interesting:

"An [sic] Gold Standard for an amplifier would be to double the power at 4 ohms. This concept is important even if you are buying an 8 ohm speaker. If the amplifier is rated at 80 watts at 8 ohms, it should (ideally) produce 160 watts at 4 ohms (or close to it). None of the receivers will do that. However, this is the benchmark of a good amplifier design. A 10 watt amplifier that produces 20 watts at 4 ohms "speaks volumes" about the PHILOSOPHY of the designer...A good receiver might produce 30-40% more power at 4 ohms. Most receiver manufacturers don't want to talk about 4 ohm ratings because they have cut the "guts" out of their products to keep the cost down. Some receivers produce the same power at 4 ohms as the 8 ohm ratings. Or they use a switch on the back for 4 ohms to reduce the power and to prevent the receiver from self destructing. Others warn against 4 ohm speakers. Regardless of what speaker you buy, we don't recommend any of these receivers. There are a few manufacturers making receivers with good 4 ohm capability. But, we can't keep up with who's doing what. All you have to remember is to ask-- "What is the 4 ohm power rating?" If the 4 ohm rating isn't available, find another model or brand." 

The specs on the Music Hall 15.2 doesn't show a 4 ohm rating. I understand that the speakers I select will determine the load placed on the amp; the B6's push 6 ohms. I then looked again at the Marantz PM 6004 - it's specs are 8 ohms/45w and 4 ohms/60w.

I may be getting too far into the weeds on this, but here are my questions:

1. How important is the power output ratio (4ohm/8 ohm) in selecting my amp?

2. Do you agree with Mag's statement that "if the 4 ohm rating isn't available, find another model or brand" even if I am purchasing speakers with a 8 or 6 ohm rating? 

Thanks for any imput!

Ariel Bitran
Ariel Bitran's picture
Last seen: 2 years 4 months ago
Joined: Jun 1 2007 - 2:14pm
hey guys - sorry

I tried to delete the duplicate post, but strangely it deleted the other -- anyway, i have all the content saved in another window and copy and pasted here:



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