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Yamaha A-S801 Integrated Amplifier Measurements and Analysis

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All measurements were conducted using our Audio Precision APx585 8 Channel HDMI Audio Analyzer following our rigid Amplifier Measurement Test Protocol

Frequency Response

All measurements of the A-S801 were done in pure-direct mode bypassing the tone and balance controls unless otherwise noted.

A-S801 Freq(192kHz, 24bit).jpg

Yamaha A-S801 Analog Frequency Response Direct Mode

Whether I measured the A-S801 via analog input or with a 192kHz/24bit test signal on the COAX digital input, I found ruler flat frequency response from 10Hz to 80kHz  - .6db.  Via the analog inputs, I measured +-.043dB Ch-Ch Deviation and a vanishingly small +-.008dB when using the digital inputs.  This is excellent.

Bass Management

The A-S801 bass management in pretty primitive but I found it very useful that Yamaha included a filtered subwoofer output. 

A-S801-Sub.jpg

Yamaha A-S801 Frequency Response with Bass Management Engaged

The -3dB point of the HPF seemed to be about 95Hz with a 12dB/oct rolloff.  Yamaha specs this at 100Hz.  Personally I would have preferred it set to 80Hz or not filtered at all since most folks using a sub will simply engage their subwoofer’s internal crossover anyways.  As previously mentioned, I recommend either bypassing your subwoofer crossover filter offsetting it +-20Hz than this filter to mimimize interactions between the two.

Signal to Noise Ratio

A-S801SNR(1 watt).jpg

Yamaha A-S801 Signal to Noise Ratio @ 1watt (CCIR filter engaged)

With a 200mVrms input, I measured > 89dB at 1 watt output and >93dB with A-wt filter engaged.  This is a great result and demonstrates why I felt the noise floor on this product was completely inaudible.

A-S801 SNR 200mVrms (CD Direct).jpg

Yamaha A-S801 Signal to Noise Ratio 200mVrms output (CD Direct, A-wt)

Yamaha specs the A-S801 to deliver 99dB (A-wt) or better SNR via the CD analog direct path driven by 200mVrms.  I was able to verify this claim as you can see in the above graph. The CD Direct engaged did improve the SNR by about .5dB.  It's not much of a difference and likely not audible given how quite the product is in any mode, but hey it's something that is verified with measurements.

The DAC performance isn't quite as pristine as the analog section but it's still good nonetheless.  At full digital scale (0dBFs, 2Vrms out), SNR was >100dB A-wt.  This translates down to 83dB at -20dBFS or 200mVrms output. 

Distortion Performance

A-S801 FFT (0dBFS).jpg

Yamaha A-S801 FFT Distortion Analysis (0dBFs)

I ran the USB-B digital interface at digital full scale (0dBFs) which yielded 2Vrms from the analog outputs to see how the ESS Sabre DAC section performed.  You can see the residuals above the 1kHz fundamental along with quantization noise were in the -103dB or lower range.  While this result isn't SOTA in terms of the best of the best DAC performance, it's still respectable and within the performance limits of the ES9010K2M spec sheet for DNR and THD+N as follows:  DNR=116dB, [email protected], -60dB.

A-S801 Freq-vs-Dist (0dBFS,AES17).jpg

Yamaha A-S801 Distortion vs Frequency (0dBFs, AES17 filter engaged)

Again I verified the distortion limits of the ES9010K2M DAC per their data sheet as being under .005% THD+N for the entire audio band.  Yamaha appeared to implement this DAC to reach within its theoretical limits of performance.

A-S801-FFT-1watt.jpg

Yamaha A-S801 FFT Distortion Analysis (1 watt)

The amplifier section of the A-S801 behaved quite well as you can see in FFT distortion analysis at 1 watt.  The distortion byproducts were > -100dB below the fundamental.  Even when driving the amp section to its 100 watt rating, I measured the distortion byproducts > -90dB below the fundamental.  This is very solid performance.

Channel to Channel Crosstalk Performance

A-S801 Xtalk.jpg

Yamaha A-S801 Crosstalk Tests (One Channel Undriven)

 

The crosstalk sweep tests I ran on the A-S801 produced very good results. At 1kHz the channel-to-channel isolation was about -90dB and –60dB at 20kHz. I consider anything less than -40dB @ 10kHz acceptable and the A-S801 beat that with 25dB to spare.  Incidentally, measured stereo separation of the A-S801 was about 20dB better at 1kHz and 15dB better at 10kHz than specified by Yamaha.

Power Amplifier Measurements

The A-S801 was tested on a dedicated 120V / 20A line.  Unless otherwise stated, all power measurements were done with the default 8-ohm impedance setting.

We tested power using three methods all of which were taken at < 0.1% THD + N:

  • Continuous Full Power Bandwidth (CFP-BW) from 20Hz to 20kHz into 8 and 4-ohm loads
  • 1kHz Power Sweep vs. Distortion (1kHz Psweep)—popularized by the print magazines, this is an instantaneous power vs. distortion test at 1kHz. The problem with this test is it often masks slew-related and or frequency response problems some amplifiers exhibit at the frequency extremes, and thus inflates the measured power results. It does provide an instant gratification number for consumers to argue over on the forums, so we are now incorporating this test to please the masses.
  • Dynamic PWR - 1kHz CEA-2006 Burst Method testing. This is a dynamic power measurement adopted from the car industry similar to IHF method, only a bit more difficult for an amplifier and more representative of real musical content.

Keep in mind most review publications don't do continuous power measurements and they usually publish power measurements into clipping at 1% THD+N. Our measurements are very conservative since we use a dedicated 20A line with no Variac to regulate line voltage.  We constantly monitor the line to ensure it never drops more than 2Vrms from nominal, which in our case was 120Vrms. 

 For more info on amplifier measurements, see:  The All Channels Driven (ACD) Test

A-S801-Freq@PWR-4ohm.jpg

Yamaha A-S801 Full Power Bandwidth Continuous Sweep (185wpc, 4 ohms)

The A-S801 produced respectable output on the continuous sweep tests.  For 8 ohms, two channels driven, output was around 105 watts/channel and 185 watts/channel for 4 ohms under 0.01% THD+N (well below clipping).  

A-S801-Psweep-2CH-8ohm.jpg

A-S801-Psweep-2CH-4ohm.jpg

Yamaha A-S801 1kHz Power Sweep Test
Top Pic: 8 ohm load, 2CH;  Bottom Pic:  4 ohm load, 2CH

The Yamaha A-S801 belted out some great power numbers with 125wpc at 1% THD+N and 118wpc at  0.1% THD+N with both channels driven into 8 ohms.  Into 4 ohm load, the A-S801 mustered 188wpc at 0.1% THD+N and about 200wpc at 1% THD+N with both channels driven.

There is a dreaded impedance switch on the back of the A-S801 that reduces the output power of this unit for certification purposes only. We recommend leaving it at the default 8 ohm setting and NEVER changing it. 

For more information see:  A/V Receiver Impedance Selector Switch

A-S801-CEA2006-4ohm-1CH.jpg

Yamaha A-S801 Dynamic Power Test (1kHz, 4 ohm load, 1CH driven)

The CEA-2006 burst tests simulate musical program material to illustrate dynamic capabilities of the amplifier.  The A-S801 produced 260wpc into 4 ohms with both channels driven and almost 300 watts with one channel drive.  At 8 ohms, I measured 165 watts which would give this amp > 2dB of headroom based on its 100 watt rating!  There's something to be said about good 'ol fashion Class AB amp design with plenty of heatsinking.

# of CH Test Type Power Load THD + N
2 CFP-BW 105 watts 8 ohms .01%
2 CFP-BW 185 watts 4 ohms .1%
1 1kHz Psweep 139 watts 8 ohms 0.1%
1 1kHz Psweep 148 watts 8 ohms 1%
2 1kHz Psweep 118 watts 8 ohms 0.1%
2 1kHz Psweep 125 watts 8 ohms 1%
1 1kHz Psweep 228 watts 4 ohms 0.1%
1 1kHz Psweep 241 watts 4 ohms 1%
2 1kHz Psweep 188 watts 4 ohms 0.1%
2 1kHz Psweep 199 watts 4 ohms 1%
2 Dynamic PWR 156 watts 8 ohms 1%
2 Dynamic PWR 260 watts 4 ohms 1%
1 Dynamic PWR 165 watts 8 ohms 1%
1 Dynamic PWR 295 watts 4 ohms 1%

    Yamaha A-S801 Power Measurement Table

Our test results validate Yamaha’s power specification for both channels driven and proved that it had plenty of reserves for dynamic power demands.  It also demonstrated excellent stability with 4 ohm loads so don't be afraid to pair it with lower impedance speakers.

 

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Recent Forum Posts:

lovinthehd posts on December 20, 2021 15:02
Pip_Boy72, post: 1526577, member: 97572
Thank you PENG and Lovinthehd. The Monolith, and Outlaw was what I had originally boiled it done to next to the Yamaha AS701. I was told about the crown amps in the XLI version but after reviewing the four I am now on the email list for when the Crown XLS 2002 will be back in stock . Again thank you both.
Looks like a few bucks more, but even a bit more power….and in stock https://www.guitarcenter.com/Crown/XLS2502-775W-Power-Amp-with-Onboard-DSP-1430749400170.gc
Pip_Boy72 posts on December 20, 2021 14:56
Thank you PENG and Lovinthehd. The Monolith, and Outlaw was what I had originally boiled it done to next to the Yamaha AS701. I was told about the crown amps in the XLI version but after reviewing the four I am now on the email list for when the Crown XLS 2002 will be back in stock . Again thank you both.
PENG posts on December 20, 2021 14:41
lovinthehd, post: 1526563, member: 61636
Or save some money and get a Crown XLS 2002 and get a bit more power than Peng's suggestions.

I don't know how I could have forgotten that one, probably a much better value.
lovinthehd posts on December 20, 2021 14:26
Or save some money and get a Crown XLS 2002 and get a bit more power than Peng's suggestions.
PENG posts on December 20, 2021 14:22
Pip_Boy72, post: 1526551, member: 97572
The vegas are rated at 200 w @ 4 ohms

I mean your actual estimated power requirement based on the loudest sound pressure level you listen to, the distance from your speakers and the sensitive of your speakers.

If you don't want to find out that's okay and in that case just get the most powerful amp you can get for you budget. So for two channel amps, I can think of the following budget oriented power amplifiers:

Monolith 200 WX2
Outlaw M2220 monoblock X 2

Monolith by Monoprice 2x200 Watts Per Channel Two Channel Home Theater Stereo Power Amplifier with XLR Inputs - Monoprice.com

These are real separate power amplifiers.

Edit: Forget the above, the XLS2002 that HD suggested is a better value. Or the XLS 1502
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