Power Rating: Onkyo vs Yamaha


Hi, everyone!

I am browsing for an integrated amplifier and I stumbled upon the Onkyo A-9150, that meets all my requirements (budget, good sound, discreet class AB design, internal DAC, pre-out, phono, the whole package), but I am really curious by its power rating.

Looking at the specs, it is rated as 60W/4-ohm and 30W/8-ohm with 0.08% THD from 20 to 20,000Hz. Okay, but the manual also states that it weighs 9.2 Kg, almost the same (even heavier) as the Yamaha A-S301, that weighs 9.0 Kg. Only the Yamaha is rated as 60W/8-ohm and 70W/4-ohm with 0.019 THD from 20 to 20,000Hz. Upon inspection of pictures over the internet, their transformers are pretty much identical, just like their chassis, and 

How come is this difference in power so big? Any ideas?

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PS.: If you look in their service manuals, I guess you will find that their topology is the same and that the Onkyo A-9150 amplifier transistors are even more powerful than the Yamaha A-S301's.
rafapb
" I have only one problem with the whole Yamaha line: no pre-amp output!"

Assuming you are speaking about the digital equipped Yamaha integrateds.  I agree at least the upper models(701 and 801) of the A-S#01 line should have right/left preouts.  The higher end line analog only(A-S1000, A-S1100, A-S2000, A-S2100, A-S3000) all do have stereo preouts.

Bill
rafapb

Sorry, but I think you're splitting hairs with the amps. For practical considerations, one is not any more powerful than the other. Also, with THD specs that low, the difference is meaningless. Years ago, some amps were manufactured with THD lower than these two, however there was an issue. They sounded horrible. One thing that is a negative for me about the Yamaha is that it uses an impedance switch when using 4 ohm speakers. This results in some type of limiting to prevent damage to the amp with a more difficult load. The Onkyo is built to be 4 ohm stable without the need for a switch. I would choose the Onkyo. I thinking it is likely the better sounding amp.

The difference is in the power supply. The Onkyo is rated into 4 ohms and the Yamaha is not. The latter is a tell-tale sign of a weak power supply (at least for a Class A/B amps).

Onkyo products have always had more robust power supplies and deliver more headroom at the same wattage rating than their competitors, thus earning merit for a strong recommendation in this class of equipment.

Dave
At the Onkyo’s retail price of $499, Yamaha’s contender is the A-S501, not the 301.

The A-S501 has the stronger power supply - two 12000μf capacitors and it’s rated to 220 watts at 2Ω for dynamic peaks. It’s "minimum" RMS power at 8Ωs is 85 watts/Ch - both channels driven.

The following review includes some measurements for ths A-S500 (501 sans DAC). It actually outputs more power than its spec sheet suggests.

https://www.avhub.com.au/product-reviews/hi-fi/yamaha-a-s3000-amplifier-review-and-test-395562

(Click on "Review and Test" link)