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Yamaha RX-596 Receiver Review

amirm

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#1
This is a review and detailed measurements of the vintage (?) Yamaha RX-596 Receiver (stereo amplifier with tuner and video switcher). It was purchased by a member from local charity (Goodwill) for US $10 plus $18 shipping. No, that is not a typo. He did buy it for just $10. It was sold "AS-IS." Shipping was likely less since the branch of the charity is local to us. If the amp in it performs, it will be the bargain of the year.

RX-596 is not that heavy relative to its size and looks as modern as today's gear:

Yamaha RX-596 Stereo Receiver Audio Review.jpg
Please excused the bowed sides. I have not screwed the lid in as I plan to clean it more before giving it back to its owner. As shipped, there was an inch of dust everywhere. OK, it was just 1/8 of an inch but it is more dramatic to say an inch! :) More on this later. Here is the back panel:

Yamaha RX-596 Stereo Receiver Back Panel Repair Audio Review.jpg

Before testing, I exercised all the controls to get rid of some of the surface dust in them. That brought most of the to life but one channel was dead. I traced that to a dirty input switcher which to my pleasant surprise, it motorized! When you change inputs, a little motor turns the input selector for you allowing for very low loss input switching (as opposed to electronic ones used in AVRs today). The motorized aspect made it very hard to get into it but I managed to clean it enough for the other channel to work. Here is a shot of the inside:
Yamaha RX-596 Stereo Receiver Teardown repair.jpg

So many surface wires to avoid using double-sided PC Board. It also has a modular configuration to allow for different inputs using vertical cards (e.g. tuner, video, etc.).

Back to its operation, even though I got the other channel working, it was noisy so I put the unit in Pure Direct and that got rid of most of the flakiness. Some remained though as you see in the review.

The owner tells me this architecture/design is used in a number of Yahama units so if measurements are good, it should apply to them as well. speaking of that, I was so pleased to see such a simple design with just two output transistors and handful of components. No fancy hard to get ICs so 'should' be easy to service if broken.

The controls feel super nice, something we sorely miss in new AVRs.

Amplifier Audio Measurements
As usual, we start with our dashboard of 1 kHz tone into 4 ohms at 5 watts:
Yamaha RX-596 Stereo Receiver Audio Measurements.png


As you see, I set the volume so that I achieved a gain of 29 dB. At lower gains, the distortion was much lower. But for fairness I went with 29 dB. Performance is slightly above average:

best stereo receivers reviewed.png


And way ahead of a number of modern AVRs:

Best AVR Measurements.png


Crosstalk performance was poor, just besting our $27 amplifier:

Yamaha RX-596 Stereo Receiver Crosstalk Audio Measurements.png


Some of this may be due to dust. In use should not be a big issue though.

Frequency response was nice and flat in audible band, reaching to 80 kHz at -3 dB point:
Yamaha RX-596 Stereo Receiver Frequency Response Audio Measurements.png


Signal to noise ratio was just decent, reaching 16 bit performance at full power:
Yamaha RX-596 Stereo Receiver SNR Audio Measurements.png


Let's get into the meat of the measurements which is power versus noise and distortion into 4 ohms:

Yamaha RX-596 Stereo Receiver Power into 4 Ohm Audio Measurements.png


What do you know? It easily beats the NAD T758! So much lower noise and distortion prior to clipping.

As you see, one channel in dark blue was complaining a bit. It complained more when I tested into 8 ohms with the first run being very bad, but this second one not so much:

Yamaha RX-596 Stereo Receiver Power into 8 Ohm Audio Measurements.png


I don't know why I cater to some of you asking me to do more work than I want to. :) But here is the 10 kHz square wave:
Yamaha RX-596 Stereo Receiver Square Wave Audio Measurements.png


I have also overlaid the Audio Precision in loopback in blue so you can see the best case scenario in the measurement. The AP's bandwidth is set to 1 Mhz. So naturally the 80 kHz bandwidth of the RX-596 rolls off the edges. Now what? What do you learn?

Conclusions
The used Yamaha RX-596 is a surprising bargain. It clearly shows how much we have gone backward in today's race to add channels to AVRs while reducing their performance. This $10 amplifier produces the same power as them and despite its age, performed well.

If you can find a working one of this series, and can have someone clean it up for you, you will have a great performing amplifier for almost nothing. Happy to recommend the used Yamaha RX-596.

--------
As always, questions, comments, corrections, etc. are welcome.

When I asked the pink panther to pose with this amp he initially refused. He said the thing is too dirty constituting animal abuse! So I gave him a steak to bribe him and he then happily posed. I worry that so spoiled, he will ask for steaks in the future. So need to plan ahead and buy a bunch. Please help fund that by donating using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Cahudson42

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#2
Wow! Nice find.. Could I ask the supplying member for a brief list of similar architecture models?

Thanks!
Chris
 

pma

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#4
"What do you learn"? Very nice step response, aperiodic, without overshoot, without ringing, without breaks at the rising and falling edge. Good stability - into resistive load. We could tell more on stability if you added parallel capacitance, like 1-2-5-10-20-50-100 nF.
 

Johnb

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#7
Thank you for testing my unit Amir, and for the extra work in cleaning it up. I have another one and it sounds very good to me. I was hoping that you would test it with CD Direct, which bypasses the input analog multiplexer, and they claim 112DB S/N. The Pure Direct keeps it in the loop.

Only the CD Direct button has a direct input to preamp. I noticed that for instance the current production A-S301 doesn't (but has Pure Direct), but the higher models do.
Various manufacturers mean various things by Direct. With Yamaha: Pure Direct-->no tone control
CD Direct-->no tone, no input multiplexer
Marantz has an option that also bypasses the volume control, like pure 2-ch amp, with higher claimed S/N

The other models are RX-596, RX-597, RX-777 (top of that line, 85W instead of 80W, 8 ohm) which should have something else extra, but I'm unsure what. There was also a line of pure integrateds, without tuner AX-497 (which preceded A=S500). AX-495.

These also include MM phono preamp, which I guess is better than today's cheaper standalone models. Too bad Amir wasted so much time cleaning - I can't bring myself to ask him to do more work.
 
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amirm

amirm

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Thread Starter #9
I didn't realize there was a CD direct. Here are a repeat of a few measurements with that:

Yamaha RX-596 Stereo Receiver CD Direct Audio Measurements.png


Noise has gone down increasing performance especially in the good channel:
Best stereo receivers.png


Signal to noise ratio shows the improvement directly:

Yamaha RX-596 Stereo Receiver SNR CD Direct Audio Measurements.png


And finally, power into 4 ohms:
Yamaha RX-596 Stereo Receiver Power into 4 Ohm CD Direct Audio Measurements.png
 

restorer-john

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#10
Yamaha's ToPART design kicked in around 1990 and it has really not changed a bit since.

It stood for Total Purity Audio Reproduction Technology. Basically, they went symmetrical mirror imaged mono design, lots of bussbars, low impedance drive capability etc. They really stepped up their offerings across the board.

There's a large range of model numbers that will all perform to a similar standard.

The motorized input selector however is the Achilles heel of these Yamahas. They must be carefully pulled down and properly cleaned. Contact cleaner is not a long term fix. Trust me. :)

This is an ax-590 motorized selector. Notice, there are two wafers, one for each channel (analog signal) and a indicator (LED) and control wafer that the micro reads.

(not my pics on this one)
yamaha-ax-570-873468.jpg


yamaha-ax-570-873472.jpg


Yamaha ditched the Alps selector as it caused way too much trouble. As a bonus, you can find receivers and amplifiers for peanuts because of it. You do not want to repair a 7 channel version of this such as on the big RXV-xxxx receivers.
 

PierreV

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#13
A few shots from a RX396RDS I own (bought new back then, probably when it was EOL given how stingy I am).
Subjectively, it still works as if it was brand new. Drives the Giyas with ease, and runs circles around similarly rated (2x50w) modern amplifiers in terms of power delivery on the LS50. Has been used for 10 years as the conservatory amplifier where temperatures range from 1C to 60C throughout the year. Never gave any trouble and the motorized pot has remained flawless.

IMG_20191211_235848.jpg

IMG_20191211_235921.jpg

IMG_20191212_000011.jpg
 

restorer-john

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#14
Never gave any trouble and the motorized pot has remained flawless.
It's the earlier motorized input selectors we are discussing, your 396 has electronic input switching- much more reliable. :)
 
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amirm

amirm

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Thread Starter #15
@amirm Please do a CEA-2006 burst test at 4 and 8 ohms if you get the chance on this Yamaha. You may be surprised...
I really worry about damaging this amp. It is not restored so I don't want to stress test it.
 

BYRTT

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#16
I don't know why I cater to some of you asking me to do more work than I want to. :) ..........I have also overlaid the Audio Precision in loopback in blue so you can see the best case scenario in the measurement. The AP's bandwidth is set to 1 Mhz. So naturally the 80 kHz bandwidth of the RX-596 rolls off the edges. Now what? What do you learn?.....
"What do you learn"? Very nice step response, aperiodic, without overshoot, without ringing, without breaks at the rising and falling edge. Good stability - into resistive load. We could tell more on stability if you added parallel capacitance, like 1-2-5-10-20-50-100 nF.
Beside the good points of @pma we learn the more work is good to see and than before a roughly tweeter + ear rolloff cascade of 2nd order 20kHz lowpass point set in for acoustic domain RX-596 looks good and probably transparent compared the green simulated junk below of a 2nd order lowpass :D thanks execute the more work and publish it :)...

ASR_3.png
 

bigx5murf

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#17
Now I really want to see a RX-Z* (z7, z9, z11) measured, I believe these were the last models built before they started going in the other direction regarding quality.
 

restorer-john

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#18
I really worry about damaging this amp. It is not restored so I don't want to stress test it.
Fair enough. :)

I can do some continuous and burst testing on some Yamaha RX and AX series I have lying around here and post them in another thread when I get the chance.
 

mhardy6647

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#19
Thanks for publishing this. I enjoyed it.
Of course I would, though, as I am a bit nonlinear when it comes to Yamaha hifi products.

DSC_0241
by Mark Hardy, on Flickr

Indeed, recently found an old Dolby ProLogic Yamaha receiver (RX-V1050) at the Grantham, NH town dump which I could not resist.
Works fine and sounds -- OK.

DSC_7312 (2)
by Mark Hardy, on Flickr

DSC_7543 (2)
by Mark Hardy, on Flickr
 
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