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Review and Measurements of Accuphase E-270 Amplifier

amirm

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#81
For the record: XLR cable plugged or unplugged at source end for this test?
Correct. I left the other end connected to the Accuphase.
 

Dialectic

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#83
That's absolute rubbish I'm afraid. I've worked on Accuphase gear from their very first products to recent models over the last 4 decades and they were and are, a considerable step up from day one.

Even their very first integrated, the E-202, produced in 1974, had construction, performance and component quality far in excess of anything else out of Japan at the time. It garnered amazing reviews and many, if not most of them, are still out there, playing tunes.

View attachment 20341

Edge connector sockets for serviceability, careful routing of cables, absolute premium components for the time and a superb range of facilities and functions, all in a rock solid 20kg unit.

View attachment 20345

View attachment 20346

All boards are socketed on edge connectors for easy service. Every part is overspecified for the job. Go have a look at some internet images of the internals and tell me what you see.

To give you an idea, the last one I worked on needed a volume knob (its original was missing) and Accuphase supplied me one. Yes, they still had spare parts, 35 years after producing the amplifier! And cosmetic parts are usually the first to dry up. Try that with any other company.
The measurements Amir performed are extremely limited. (no doubt due to time constraints). I certainly feel a categorical recommendation or lack thereof is a very unwise position to take.

What we can see, is the performance exceeded rated specifications by a wide margin (factors of 10+) for the parameters Amir tested. This was as expected and as I predicted. Frequency response tests appear to exceed spec also, but Amir has not specified the power output level he tested FR at. The standard and the spec is 1W. We can only guess what he used.

The high level preamplifer inputs were driven with a signal to give the same level out as in (2V). There is absolutely no point using a preamplifier that is specified with an 18dB gain and then winding back the attenuator to give unity gain for testing purposes. All preamplifiers are tested and specified at the wide open position and have been forever. The rated output of the preamplifier is 1.07V from a 134mV input. He fed it 2V and wound back the attenuator. You test a preamplifier at its rated input and output, not some made up number that suits you. We may be merely seeing non-linearities and noise (hum) etc, from being buried in the multiple stages of the AAVA volume control (see below).

View attachment 20348
I had hoped Amir would investigate this unusual implementation and test it at various increments/levels to give some insight into its performance or lack thereof. I'm not convinced piling VI buffers in line is a good idea, but who knows. Accuphase have been touting their AAVA for several years now.

View attachment 20347

One cannot characterize the performance of an amplifier with only one resistive load test (4 ohms), which is half the standard, and make no comparisons between different loads and different numbers of channels driven. There is no reactive testing, transient (IHF/EIA) testing, power bandwidth, shorted input residual, comparisons of various inputs, crosstalk measurements, etc.

There is zero discussion on the topology as the cover was likely not removed (understandable if it was on loan) and therefore we can only surmise as to the reasons for the burst of HF hash on the FFT. I have offered a possible reason in a previous post, but Accuphase is unlikely to have released a product into the wild with such an issue. It may be operator influenced perhaps.

The power amplifier stage is conventional and of a decent standard according to what I see on Accuphase's brochure.

View attachment 20349

What we can see is Accuphase appear to have decoupled supplies for the VA, the driver stage and the output stage and we know they will have high quality regulated supplies for the preamplifier stages. Amir makes the statement the preamplifier supplies are being affected by the output. This is perfectly normal in integrated amplifers with single transformers when operated at high powers into low impedances.

Comparisions to the Hypex are flawed. The Hypex units have not demonstrated they can even hit their specifications. Nor have they demonstrated they can be trusted not to shut down at inopportune times. Their power supplies overheat and are failing in the marketplace. The Accuphase wasn't pre-conditioned, or tested for 5 minutes at full rated power either.

I take the whole review with a grain of salt.

That said, further investigation would clear up a whole lot of the above. Time contraints are a b#tch.
No one can reasonably contest the view that Accuphase gear looks nice internally and externally and is constructed with quality components with long-term spares availability. But Amir's measurements indicate performance deficiencies in the E-270 that should not be present in a $4,500 integrated amplifier.

Other than the objection that Amir should standardize his measurements, I've seen no serious argument that his measurements are flawed or that they do not indicate engineering shortcomings in the E-270. That's the news here. We can wax poetic about build quality, etc., but most of us here do not seriously believe that luxurious build quality benefits the sound.

Accuphase, McIntosh and some other brands continue to manufacture equipment that looks nice and evokes nostalgia about systems of the past. I have no objection if you like such equipment, but as the measurements here and elsewhere continue to demonstrate, this equipment does not represent the future--or the present--of high-performance audio.
 

jasonq997

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#84
No one contests that Accuphase gear looks nice internally and externally and is constructed with quality components with long-term spares availability. But Amir's measurements indicate deficiencies in the E-270 that should not be present in a $4,500 integrated amplifier.
I think this is the key point. All of the other virtues and the illustrious history of the company don't matter as it relates to this argument.[/QUOTE]
 

restorer-john

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#85
I think you are being a bit harsh on the review. There is clearly an issue with mains pickup and other spuria on this unit which wrecks a lot of the numbers. Perhaps that isn't typical of Accuphase products but there is no doubt the NC400 is significantly cleaner than this particular example. More / different tests won't change that, unless it is considered faulty.

BTW the replacement power resistor arrived so I will be doing the 5 min test later on at least one of the hypex amps. Also I think one person replied to the forum about failed psus
With all due respect to you Alan, I have zero vested interests in either the Accuphase or the Hypex amplifiers. You cannot say the same. I'm not sure which part you want to call me out on as being incorrect or 'harsh', but my issues were with the spectrum and nature/number of tests and what interpretations could be drawn from them. That has been addressed going forward.

Regarding failed PSUs, I posted some links I found after a very brief search on the internet for failed PSUs manufactured by Hypex. Clearly they run hotter than they should, that has been demonstrated. Clearly they will fail in time, as they are no different to the hundreds (or more) of SMPS supplies I have repaired over the years, excepting that most equivalent 600W SMPS supplies are fan-cooled and/or enclosed in vented casework with substantial heatsinking- none of which the Hypexes typically have in actual typical use. I have written on this in several threads.

As for me, I keep hundreds of typical 105 degree low ESR capacitors of most used values for SMPS rebuilding- such is the frequency of failure in CE SMPS powered gear. SMPS problems have become the most frequent source of failure across the board. Linear transformer based PSUs rarely fail, in fact I can count the number of outright failed transformers on one hand, in over 30+ years.

More will come to light on the durability, or lack thereof of these Hypex SMPS PSUs as the years wear on.

Anyway, I look forward to your tests in your thread. Don't burn your fingers on those heatsinks! :)
 

restorer-john

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#86
But Amir's measurements indicate performance deficiencies in the E-270 that should not be present in a $4,500 integrated amplifier.
There is a cluster of noise which is atypical of any spectrum I've ever seen on an analog Class AB amplifier. There is more to investigate as it makes no sense, but time is an issue- the amp had to go back to the store. That is, unless as I mentioned, the uP/display MPX/ key scanning is active and/or inherently faulty.

Has anyone else ever seen anything like it? The only times I have, is when something was interfering (VFDs, a computer, a mouse (computer mouse- not the four legged variety), WiFi, a nearby SMPS supply, an LED lights above my bench etc).
 

Dialectic

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#87
With all due respect to you Alan, I have zero vested interests in either the Accuphase or the Hypex amplifiers. You cannot say the same. I'm not sure which part you want to call me out on as being incorrect or 'harsh', but my issues were with the spectrum and nature/number of tests and what interpretations could be drawn from them. That has been addressed going forward.

Regarding failed PSUs, I posted some links I found after a very brief search on the internet for failed PSUs manufactured by Hypex. Clearly they run hotter than they should, that has been demonstrated. Clearly they will fail in time, as they are no different to the hundreds (or more) of SMPS supplies I have repaired over the years, excepting that most equivalent 600W SMPS supplies are fan-cooled and/or enclosed in vented casework with substantial heatsinking- none of which the Hypexes typically have in actual typical use. I have written on this in several threads.

As for me, I keep hundreds of typical 105 degree low ESR capacitors of most used values for SMPS rebuilding- such is the frequency of failure in CE SMPS powered gear. SMPS problems have become the most frequent source of failure across the board. Linear transformer based PSUs rarely fail, in fact I can count the number of outright failed transformers on one hand, in over 30+ years.

More will come to light on the durability, or lack thereof of these Hypex SMPS PSUs as the years wear on.

Anyway, I look forward to your tests in your thread. Don't burn your fingers on those heatsinks! :)
This is one of the reasons I did not buy the Kii Threes. Whenever I've spent any time listening to them, I've put my hand on them and could feel significant heat from the six NCore amplifiers inside. But those NCores sure do sound good--and almost undoubtedly better than the amplifier inside the Accuphase E-270 does.
 

March Audio

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#88
With equal respect the plots from the Accuphase test show some obvious problems yet you are seemingly very keen to defend it.

I wouldn't buy that Accuphase due to those problems shown, especially at that price.

Regarding the Hypex amps the NC400 has been around for about 6 years. There will be failures as I'm sure there are with any electronics, including Accuphase. However I haven't seen mass complaints about.

Oh the "tower of power" dummy load has a big fan on it now :)
 
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#89
While I agree with the complaints about Hypex's power supply, I'm not sure it's fair to discount the whole amplifier's performance because of an underpowered, underheatsinked power supply. There are plenty of commercially sold units that use 1 SMPS1200 per NC500 module, and those are much less likely to have heat issues compared to the tested DIY unit. In addition, manufacturers could certainly include additional heatsinking.

In other words, if you need the power and thermal capacity it's very easy and simple to add it. In contrast, it's far more difficult to produce a module that measures as well as the NC400 does.
 

restorer-john

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#90
While I agree with the complaints about Hypex's power supply, I'm not sure it's fair to discount the whole amplifier's performance because of an underpowered, underheatsinked power supply
We've addressed all that in the DIY hypex amp thread. I don't think you can however use a product that only functioned part of the time during soak/full power testing, overheated, shutdown and failed to reach its specifications as a reference point to compare commercial offerings to.

With equal respect the plots from the Accuphase test show some obvious problems yet you are seemingly very keen to defend it.
I'm not defending it, I'm saying due to the unusual nature of the noise, I would be investigating it further and ruling out whatever I could before pointing the finger at Accuphase's design. The remainder of the test results show a very competent design.

And, for the record, I wouldn't be buying the Accuphase at USD$3500 in any case, with or without the 'problems', I don't believe it fits my value requirements. I think it is way too much money for what is essentially an 'entry level' Accuphase in real terms. I have a 1990 C-11 Accuphase preamplifier that was AU$3500 when new and probably when paired with its matching power amp (P-11) was a step up over the modern integrated reviewed here. I also have some older integrated Accuphase amps, but they are stored.
 

Sylafari

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#91
I just find it odd that for such an established high end audio company they can accept that the balanced performance will be lower than Main In or High Level Input. They literally know this fact as it is in their printed specifications and seem to be perfectly fine with it for a $4500 audio product. Seems a bit egregious to me.
 

March Audio

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#92
We've addressed all that in the DIY hypex amp thread. I don't think you can however use a product that only functioned part of the time during soak/full power testing, overheated, shutdown and failed to reach its specifications as a reference point to compare commercial offerings to.



I'm not defending it, I'm saying due to the unusual nature of the noise, I would be investigating it further and ruling out whatever I could before pointing the finger at Accuphase's design. The remainder of the test results show a very competent design.

And, for the record, I wouldn't be buying the Accuphase at USD$3500 in any case, with or without the 'problems', I don't believe it fits my value requirements. I think it is way too much money for what is essentially an 'entry level' Accuphase in real terms. I have a 1990 C-11 Accuphase preamplifier that was AU$3500 when new and probably when paired with its matching power amp (P-11) was a step up over the modern integrated reviewed here. I also have some older integrated Accuphase amps, but they are stored.
...and we also adressed the fact that the test is totally unrealistic. you know it would never shut down in real world use. ;)

So considerded opinion is that the Accuphase is faulty? Thats fair enough and does need investigating.
 
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amirm

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#93
There is a cluster of noise which is atypical of any spectrum I've ever seen on an analog Class AB amplifier. T
This is what it is doing with my analyzer hooked up to its power amp (pre-amp isolated) but not turned on:

1547524477014.png


Clearly something is running around there.

We can see the same switching noise with the analyzer turned on but at very low level (0.1 millivots):

1547524668926.png


Here is the residual signal (amplified):

1547524741945.png


Seems like every 4.5 milliseconds or so something is glitching.
 

restorer-john

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#94
This is what it is doing with my analyzer hooked up to its power amp (pre-amp isolated) but not turned on:
The amplifier is not turned on? As in live power, but in standby?

So 'hooked up to its power amp' meaning the speaker terminals?

The amplifier doesn't use relays for speaker connection switching, it uses MOSFETs and likely a whole bunch of uP control. Maybe that's the standby key scanning getting in somehow? Is it a soft power switch (momentary)? I cannot see how you could get noise like that from an amplifier in the off state otherwise. There's a bunch of amplifiers in subwoofers that mute the input stage and leave the entire amplifier running 24/7 when in 'standby' but Accuphase would never do something like that.
 

amirm

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#95
At very least, amplifiers should be tested at their permitted loads, 2,4,8 ohms both channels operating, and with 2uF in parallel to simulate a reactive load.
Here is a comparison of 1 to 50 watts in 5 steps with a 4 ohm load with a 2.3 uF capacitor in parallel. Bandwidth is 45 kHz so it includes some of the high frequency harmonics and AES-17 40 kHz filter is there for both devices: (click on image for large size)

Accuphase E-270 Integrated Amplifier Power Amp THD vs Power Capacitive Load Measurements.png


The capacitor reduces the effective impedance at higher frequencies so upsets both amplifiers in that region. The Hypex NC400 though, has lower noise and distortion across the board and power levels. At 50 watts, the Accuphase E-270 nearly reaches up to 2% distortion around 15 kHz whereas the NC400 stays around 0.1% distortion.
 

amirm

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#96
The amplifier is not turned on? As in live power, but in standby?
No, the amp is fully on but the analyzer output was off. The pulses come after a few seconds after power on which I suspect is when the output is turned on.
 

amirm

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#97

restorer-john

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#98
The pulses come after a few seconds after power on which I suspect is when the output is turned on.
Control circuitry noise getting into the analogue power amp stage is not a good look for Accuphase. :(

I'll dig out my old C-11 preamp, I swear it shuts down the micro altogether in the absence of key presses. It's encased in a shielded box on the PCB too.
 
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#99
Looking at the specs from the integrated series, I notice that the stated S/N difference between RCA and XLR diminishes as you walk up the model ladder on the class A/B designs:
In E-270 shorted an A weighted at output: High level 106 dB - Balanced 91 dB - main in 122 dB
In E-370 shorted an A weighted at output: High level 107 dB - Balanced 97 dB - power in 123 dB
In E-470 shorted an A weighted at output: High level 109 dB - Balanced 102 dB - power in 125 dB

This leads me to believe that this is a difference that is planned and does not have to do with any faulty quality control on the E-270 sample tested.

Interestingly the class A E-650 has no difference between high leve and balanced. They are both 102 db. The main in has 117 db. So in that model you have lost 7 db in the high input but not gained anything in the balanced input compared to E-470. The main in at 117 db is also surprisingly 5 db lower than the entry level E-270.
 
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Thank You Amir for these tests!
I know its a heresy here, but I'll ask for it: if you have the time, I would like to read about your subjective listening experience, either by comparing it to Hypex NC-400 and/or your home reference amp. I know that you have a trained ear and I'd really appreciate your opinion.
 
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