• Welcome to ASR. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Accuphase C-280 Review (Preamplifier)

PristineSound said:
Not at this level of quality craftsmanship.

And as such, there will be no pride of ownership.
Click to expand...
I'm not suggesting it would be the same standard of craftsmanship, only that it would be interesting and for the money I'm sure it would be a nice thing to own in its own right
 
Sokel said:
They could, easily I guess.
But for a comparable performance, reliability, warranty, pre and after sale support and premium feeling (down to the knobs) and certifications, price wouldn't be far off.
Click to expand...
Haha, I think the price would be cheaper, but they wouldn't go all out for all the certification etc as it wouldn't be worth it
 
VientoB said:
Haha, I think the price would be cheaper, but they wouldn't go all out for all the certification etc as it wouldn't be worth it
Click to expand...
Like a fake Gucci?
The thing is that, if you skip the certifications you can end-up wearing radioactive polyester instead of Egyptian cotton o_O

At electrical gear is also ok if you rent and don't own the house I guess.
In general, cutting corners is not the Accuphase way. They probably even add corners :)
 
Mart68 said:
This is not helping with my Accuphase obsession. It was already quite bad.

Still exceeding spec after forty years! Death where is thy sting?
Click to expand...
Seriously, I already had an Accuphase problem and this really kicked it into high gear. Good grief, what a stunner.
 
I too have an obsession with Accuphase products. And as much as I would love to buy an entire Accuphase stack, but it would be a very bad decision for my financial health. An Accuphase integrated costs easily over $10k. I just have to admire from afar and buy something that is more palatable for my wallet :)
 
PristineSound said:
I too have an obsession with Accuphase products. And as much as I would love to buy an entire Accuphase stack, but it would be a very bad decision for my financial health. An Accuphase integrated costs easily over $10k. I just have to admire from afar and buy something that is more palatable for my wallet :)
Click to expand...
I'd buy on the secondary market myself. I'd have to come out of retirement to even afford that!
 
Mart68 said:
I'd buy on the secondary market myself. I'd have to come out of retirement to even afford that!
Click to expand...
I would love to have this guy here. But yeah, one might have to settle for the used market :)


1763936903684.png
 
NTTY said:
Hello Everyone,

This a review and detailed measurements of the Accuphase C-280 peamplifier.

View attachment 492071

Accuphase C-280 - Presentation

This unit is from a friend who wanted to know how it performs and is ok to let me report the results, thanks to him!

Released in 1982, the C-280 was the top of the line preamp from Accuphase. It was sold at a very high price, one that if converted to today's money would make it close to $15k!

The crazy weight of 18kg does not translate into an extremely busy front face, on the contrary. In their brochure, Accuphase said they minimized the controls to the bare minimum, meaning no tones control for instance. But, as always with Accuphase, devil is the details.

So, here are the available functions, apparent or hidden behind the front bottom door:
  • Volume button from the stars: Accuphase has been paying attention to the touch and feel of the volume button for years. This one comes from somewhere in our galaxy, and we got lucky it landed on earth. There are no words to describe the feeling of using it to increase/decrease the volume. Not only that, but it is of extreme precision, especially at high volumes which eased very much some of my calibrations for measurements.
  • Subsonic filter: yes of course, it's coming from an era of Vinyl where this one was mandatory, and it seems new joiners of MM/MC phono preamp forgot why we needed it.
  • Mono/Stereo switch: so useful!
  • MC Load selector: 10 ohms, 30 ohms and 100 ohms for coupling MC cartridges.
  • Tape monitor: the youngest of you will not know why, once upon a time, we needed to record on external medium :-)
  • Left and Right Channel gain attenuation: No balance available but these two allow for it. They will reduce the output gain of respective channels by an extremely precise 0.5dB (up to -6dB) or 1dB (beyond -6dB) per step, as I measured them.
  • Loudness compensator: No tones control, but the loudness contour offers two positions that will vary with the position of the volume button.
  • Gain attenuation: overall gain attenuation -20dB, -30dB or infinite

Detail of the details: The general gain attenuation button, not hidden, has two position on the right -20dB or -30dB, to allow attenuation when doing fast-forward/rewind of our ancient Cassette decks or R2R, when searching for a track. And, turn the same button on the left for instant infinite attenuation of the output, so that the owner can respond to a phone call, as the brochure says :cool:

But, but, but, no phones out? Oh come on...

The back of the C-280 shows the magnificent custom RCA rhodium platted connectors:

View attachment 492077

There's only one balanced output connector, while we get two for RCA, allowing to drive two stereo amplifiers at the same time from them.

At the time, an input named "Disc" meant turntable, nothing else. We get two here (MM and MC switchable), and three additional high level inputs, one labelled Tuner.

Oh, and before I go to measurements, I need to mention that Accuphase was providing a good set of them, in their brochure, as all brands should. Not only we get a very detailed set of specs, we also get equally tangible graphs like these:

View attachment 492085

Accuphase said all specs were guaranteed, meaning they are the minimum that the customer would get. We'll check if the C-280 still delivers more than 40 years later...

View attachment 492086

The build quality of this device is staggering, as always with Accuphase. And being a high-end one, it is further refined here.

There is something that looks promising below the wooden case:

View attachment 492287

Let's go inside, oh yeah:

View attachment 492087

Speechless, I am. I did this picture in black and white to add a little drama to it. Did you stop scrolling and pause on it for an instant? Yeah, I know :)

This device not being mine, I did not go too far in dismantling it. But here is another picture with the 3mm thick aluminium top plates removed:

View attachment 492092


So, as you guessed, I'm sure, this a dual mono preamplifier. The three encapsulated cards are for respectively low and high level preamp heads, and the RIAA curve correction + equalization functions. The logic board is hidden, and located behind the front plate.


User experience

Well, what can I say?

Hearing the relays clicking when going from one source to the other tells a story that systematically starts by "Once upon a golden hour...". It’s a finer indulgence than reaching for whisky.

Like I already explained, the volume knob whispers elegance, it feels like caressing silk and is a quiet celebration of craftsmanship.

View attachment 492284

Now, Gentlemen, start your engines, time has come for measurements:

View attachment 492096


Accuphase C-280 - Measurements (Line)

It was not an easy task for me to test this old legend, especially the Phono performances that has put to the limits my measurement set.

All measurements were performed with an E1DA Cosmos ADCiso (grade 0), and the Cosmos Scaler (100kohms from unbalanced input), for capturing analog outputs of the Accuphase. I used a high performance DAC, the Topping D50III, as the generator with REW Software from a laptop. All these devices run on batteries, and the D50III was behind a USB isolator, to prevent as much as possible any ground loops.

I won't be necessarily following Amir's way of measuring such an item because I don't use an AP, and I wanted to check and compare the claims of Accuphase. So you can't directly compare to what Amir shows here, although it's not completely deviating.

I feel it's not nice, for this more than 40 years old device, to treat it like I've done. But, hey, are we not on this site for that one reason? Does it delivers? And does it still delivers after more than 40 years of duty services? Let's find out.

Unless otherwise noted, all measurements are from RCA outputs. The two channels were matched a 0.1dB, which good. Phase is of course completely flat. And the two channels had the excat same performances.

----

So, let's start with the SINAD view:

View attachment 492118

Pushed hard, to the limits, we get 109dB SINAD, respectable. This is with the Topping D50III (set to 2Vrms output) delivering 0.5Vrms, meaning it is at -12dBFS output, which inevitably means it lost 2bits of resolution.

The above is an unlikely scenario though, because what amplifier needs 8Vrms at its input? Or maybe a low gain highly linear one?

So, let's now increase the Topping output to 2.5Vrms, and send a 1kHz sine @0dBFS into the Accuphase, and ask it to output the same voltage, which means unity gain:

View attachment 492129

Yep, 1 bit lost. But you can appreciate the vanishingly low distortion. Actually, it's the one of the Topping, not the Accuphase. Every time I thought I found distortion from the Accuphase, it was the one of the Topping...

The reason for that degradation is that this preamp has been designed to increase the input voltage with a high gain. This is where it excels, and we'll see that when we go to the Phono stage measurements.

----

Note the very low level of power supply related leaks (below -130dBr), meaning a very silent device, especially after 40+ years!

View attachment 492130

I overlaid the two channels on that view. It is in linear frequency scale for compatibility with the same view from Stereophile (eg: Rotel Michi P5)

----

Let's continue with the famous Multitone that a lot of you, including me, like so much:

View attachment 492121

This is from the file that @amirm shared some time ago, created from the AudioPrecision. So with that one, you can compare. The trace is really beatiful and means a distortion free-range of nearly 20 bits. Gran dad is still in very good shape, I'd say.

----

I could not measure the bandwidth... because I strictly measured the one of the Topping, up to 350kHz! So only for illustration, this is the bandwidth of the Topping, with its filter set to MODE 1 and with a sampling rate of 48kHz, and measured at the output of the Accuphase, of course:

View attachment 492122

At least we get to see the channel imbalance of 0.1dB, but on a bandwidth perspective, the Accuphase is completely transparent.

----

Oh, yes, another measurement that you can use to compare with other devices. It is the THD+N ratio vs frequency, with an extended bandwidth to capture all distortion and noise components up to 90kHz:

View attachment 492123

In 1982, I'm sure nobody thought about such a punishing test. But the Accuphase stays at 0.001% (-100dB) which is much more than reasonable.

----

The below IMD SMPTE sweep vs input level is not comparable to the same test from Amir, because it is excluding noise:

View attachment 492127

The trace shows a sweet spot at 1Vrms, and note I was at unity gain on this test. This last test confirms that the Accuphase is free from any type of distorsion.

----

Other measurements (not shown):
  • Input clipping at just above 20dBu (7.8Vrms).
  • Output voltage clipping: above 10Vrms (I can't measure more).
  • Dynamic Range (CCIR 2k weighted): from 100dB at unity gain to 120dB at max gain.
  • IMD AES (18kHz + 20kHz 1:1) : below -120dB from unity gain and above!
----

The line stage of this preamplifier offers staggering performances, in today's world, and they were absolutely unnecessary at the time, since no source was anywhere close to these performances. I guess the C-280 was pleased to see higher resolution devices join his game, but had to wait 5 long years for that (with the Accuphase DP-70 here below). And even so, it had headroom for more than that. Incredible.

View attachment 492289


The Accuphase C-280 is the pure definition of a preamplifier: straight wire with gain.


Accuphase C-280 - Measurement (Phono MM)

Spoiler Alert: Ok, so, that thing has been designed to be a Phono preamp, before everything else, I tell you. Let's see what you have to tell us, Mister HEAD AMP:

View attachment 492315

For what follows, I will be talking only MM simply because my poor Topping D50III (used as the generator for these tests) is not linear enough to create a decently silent 0.5Vrms output that would suit MC input. So I measured only the noise of the Topping in that case. Boring. With MM, I got results I can use, since the noise floor was low enough to get good results.

Let's start with the standard SINAD, again not comparable to what Amir usually does and I'll explain why:

View attachment 492133

This is the signal as it comes out from the Phono preamp, meaning I did not compensated the RIAA curve. The results are staggering, I mean we are close to CD Audio!

Now, let's correct the RIAA curve, with the software, to simulate how a record would be created, with the opposite curve:

View attachment 492134

Ok, we lost 12dB because you see the noise after 1kHz being higher, which is what the RIAA curve correction does. Now this is also extremely good result, no cartridge offers that linearity. Look at the distortion nearly absent, and you know what? It's the one of the Topping that is providing the test signal!

Why 40mVrms input when Amir uses 5Vrms for this test? For two reasons:
  1. The Topping does not provide a good enough signal at 5mVrms, simple.
  2. Because some dynamic cartridges (eg: Shure M44-7 - 9mVrms for 5cm/sec), together with over-cut records, would be reaching a speed velocity of 30cm/sec, meaning they'd be at or beyond 60mVrms.
And to add to that, I'm using a 40dB gain amplification, as this is very common, and so with 40mVrms at the input, we get 0.4Vrms at the output, for the above test.

----

Next important set of measurements for a phono preamp is related to the above. It is important to know at what point it will clip, depending on the frequency. We need a good headroom, and all ancient phono preamps where known to have very good headroom. That's measured with a sweep of THD vy input level, at different frequencies. Let's check what our big bo(y)x has to say:

View attachment 492143

When I first saw the results of the sweeps, they made me laugh. The Accuphase clips past 300mVrms at 1kHz. That is giganticnormous :eek:
And look, at 10kHz, it does not reach 1% distortion with 2.5Vrms input!!!

Not only that, but the level of distortion is very low, and again we actually see the one of the Topping D50III, one of the best in class most linear DAC in existence.

The Accuphase will never break a sweat - it makes the laws of audio look lazy.

----

Ok, bandwidth, as we need to check the respect of RIAA curve:

View attachment 492148

Accuphase said "guaranteed +-0.2dB", I see below +0.1dB. Well done. Don't forget, 40+ years old...

----

Oh, yes, for the fun, as @amirm likes the below measurement. It is a sweep of THD only (no noise) with an extended bandwidth up to 90kHz to capture distortion at high frequencies too:


View attachment 492153

I did the above with two different input levels (5mVrms and 10mVrms), at respectively 52dB and 40dB. Well, the distortion we see does not come from the Accuphase, but one more time, you know...

The phono stage of the Accuphase C-280 is outstanding.


Conclusion

I've been preparing this review for weeks, spent countless hours performing measurements, and so many more to prepare the script and write this review. It was a personal investment, an adventure worth every single hour spent on this fantastic piece of engineering.

I initially thought it was unfair to torture this old device as we'd do on modern ones. But my friend convinced me to go for it. And oh boy...

This isn’t a preamplifier, it’s an artist in disguise. And it knows about architecture: I can't resist to share one last picture:

View attachment 492160

Yes, certainly, some modern devices can beat it, but you have to search hard for them. And what will remain of them in 40+ years? I'd be curious to know, but I'm unlikely to be around, considering my age and genes.

At the end of the day, Accuphase said the specs were guaranteed… and they could have added "for at least 40 years".

I hope you enjoyed this review as much as me writing it.

Happy weekend!

Flo
Click to expand...
Thanks for this.
 
NTTY said:
The Topping does not provide a good enough signal at 5mVrms, simple
Click to expand...
Thank you for the great review! I love those shielded preamp modules!

Re Topping and 5mV - if I might suggest, build a 1k/100ohm resistive divider and put it into a shielded metal housing with 2 audio connectors. You will reduce both output level and noise of the Topping DAC to get a low noise, low distortion signal.
 
NTTY said:
Well, it:
- doesn’t guzzle gaz nor require an expensive mandatory insurance
- doesn’t require service, obviously
- doesn’t ask much besides some electricity
- doesn’t promise, just delivers
- doesn’t go with half of what you own when you want a divorce, actually on the contrary, you would get you good money back many many years later

If I know a lot of stupid investments, I don’t think this is one.
Click to expand...
It's a great investment actually, if it's that great after 40 years, even if it would need a thorough service i'm sure it can go for another 30-40 years
now that's high end to me, wish i had the money:(
 
Ler0ck said:
Anyway, SNR can’t pass the CD standards then It isn’t good enough.
Click to expand...
Measured SNR is -112db on the SINAD test and -104.2dB on the 1kHz test - between 8 and 17dB lower (or less than half the noise) than theoretical best case performance for 16bit digital audio (-96dB, though in practice it's typically more like -90dB).
 
Thanks for the great review!
What a piece of engineering beauty from the past! :oops:
They really delivered. For a price, but hey - they are still around 40 years later! ;)
 
NTTY said:
Hello Everyone,

This a review and detailed measurements of the Accuphase C-280 peamplifier.

View attachment 492071

Accuphase C-280 - Presentation

This unit is from a friend who wanted to know how it performs and is ok to let me report the results, thanks to him!

Released in 1982, the C-280 was the top of the line preamp from Accuphase. It was sold at a very high price, one that if converted to today's money would make it close to $15k!

The crazy weight of 18kg does not translate into an extremely busy front face, on the contrary. In their brochure, Accuphase said they minimized the controls to the bare minimum, meaning no tones control for instance. But, as always with Accuphase, devil is the details.

So, here are the available functions, apparent or hidden behind the front bottom door:
  • Volume button from the stars: Accuphase has been paying attention to the touch and feel of the volume button for years. This one comes from somewhere in our galaxy, and we got lucky it landed on earth. There are no words to describe the feeling of using it to increase/decrease the volume. Not only that, but it is of extreme precision, especially at high volumes which eased very much some of my calibrations for measurements.
  • Subsonic filter: yes of course, it's coming from an era of Vinyl where this one was mandatory, and it seems new joiners of MM/MC phono preamp forgot why we needed it.
  • Mono/Stereo switch: so useful!
  • MC Load selector: 10 ohms, 30 ohms and 100 ohms for coupling MC cartridges.
  • Tape monitor: the youngest of you will not know why, once upon a time, we needed to record on external medium :-)
  • Left and Right Channel gain attenuation: No balance available but these two allow for it. They will reduce the output gain of respective channels by an extremely precise 0.5dB (up to -6dB) or 1dB (beyond -6dB) per step, as I measured them.
  • Loudness compensator: No tones control, but the loudness contour offers two positions that will vary with the position of the volume button.
  • Gain attenuation: overall gain attenuation -20dB, -30dB or infinite

Detail of the details: The general gain attenuation button, not hidden, has two position on the right -20dB or -30dB, to allow attenuation when doing fast-forward/rewind of our ancient Cassette decks or R2R, when searching for a track. And, turn the same button on the left for instant infinite attenuation of the output, so that the owner can respond to a phone call, as the brochure says :cool:

But, but, but, no phones out? Oh come on...

The back of the C-280 shows the magnificent custom RCA rhodium platted connectors:

View attachment 492077

There's only one balanced output connector, while we get two for RCA, allowing to drive two stereo amplifiers at the same time from them.

At the time, an input named "Disc" meant turntable, nothing else. We get two here (MM and MC switchable), and three additional high level inputs, one labelled Tuner.

Oh, and before I go to measurements, I need to mention that Accuphase was providing a good set of them, in their brochure, as all brands should. Not only we get a very detailed set of specs, we also get equally tangible graphs like these:

View attachment 492085

Accuphase said all specs were guaranteed, meaning they are the minimum that the customer would get. We'll check if the C-280 still delivers more than 40 years later...

View attachment 492086

The build quality of this device is staggering, as always with Accuphase. And being a high-end one, it is further refined here.

There is something that looks promising below the wooden case:

View attachment 492287

Let's go inside, oh yeah:

View attachment 492087

Speechless, I am. I did this picture in black and white to add a little drama to it. Did you stop scrolling and pause on it for an instant? Yeah, I know :)

This device not being mine, I did not go too far in dismantling it. But here is another picture with the 3mm thick aluminium top plates removed:

View attachment 492092


So, as you guessed, I'm sure, this a dual mono preamplifier. The three encapsulated cards are for respectively low and high level preamp heads, and the RIAA curve correction + equalization functions. The logic board is hidden, and located behind the front plate.


User experience

Well, what can I say?

Hearing the relays clicking when going from one source to the other tells a story that systematically starts by "Once upon a golden hour...". It’s a finer indulgence than reaching for whisky.

Like I already explained, the volume knob whispers elegance, it feels like caressing silk and is a quiet celebration of craftsmanship.

View attachment 492284

Now, Gentlemen, start your engines, time has come for measurements:

View attachment 492096


Accuphase C-280 - Measurements (Line)

It was not an easy task for me to test this old legend, especially the Phono performances that has put to the limits my measurement set.

All measurements were performed with an E1DA Cosmos ADCiso (grade 0), and the Cosmos Scaler (100kohms from unbalanced input), for capturing analog outputs of the Accuphase. I used a high performance DAC, the Topping D50III, as the generator with REW Software from a laptop. All these devices run on batteries, and the D50III was behind a USB isolator, to prevent as much as possible any ground loops.

I won't be necessarily following Amir's way of measuring such an item because I don't use an AP, and I wanted to check and compare the claims of Accuphase. So you can't directly compare to what Amir shows here, although it's not completely deviating.

I feel it's not nice, for this more than 40 years old device, to treat it like I've done. But, hey, are we not on this site for that one reason? Does it delivers? And does it still delivers after more than 40 years of duty services? Let's find out.

Unless otherwise noted, all measurements are from RCA outputs. The two channels were matched a 0.1dB, which good. Phase is of course completely flat. And the two channels had the excat same performances.

----

So, let's start with the SINAD view:

View attachment 492118

Pushed hard, to the limits, we get 109dB SINAD, respectable. This is with the Topping D50III (set to 2Vrms output) delivering 0.5Vrms, meaning it is at -12dBFS output, which inevitably means it lost 2bits of resolution.

The above is an unlikely scenario though, because what amplifier needs 8Vrms at its input? Or maybe a low gain highly linear one?

So, let's now increase the Topping output to 2.5Vrms, and send a 1kHz sine @0dBFS into the Accuphase, and ask it to output the same voltage, which means unity gain:

View attachment 492129

Yep, 1 bit lost. But you can appreciate the vanishingly low distortion. Actually, it's the one of the Topping, not the Accuphase. Every time I thought I found distortion from the Accuphase, it was the one of the Topping...

The reason for that degradation is that this preamp has been designed to increase the input voltage with a high gain. This is where it excels, and we'll see that when we go to the Phono stage measurements.

----

Note the very low level of power supply related leaks (below -130dBr), meaning a very silent device, especially after 40+ years!

View attachment 492130

I overlaid the two channels on that view. It is in linear frequency scale for compatibility with the same view from Stereophile (eg: Rotel Michi P5)

----

Let's continue with the famous Multitone that a lot of you, including me, like so much:

View attachment 492121

This is from the file that @amirm shared some time ago, created from the AudioPrecision. So with that one, you can compare. The trace is really beatiful and means a distortion free-range of nearly 20 bits. Gran dad is still in very good shape, I'd say.

----

I could not measure the bandwidth... because I strictly measured the one of the Topping, up to 350kHz! So only for illustration, this is the bandwidth of the Topping, with its filter set to MODE 1 and with a sampling rate of 48kHz, and measured at the output of the Accuphase, of course:

View attachment 492122

At least we get to see the channel imbalance of 0.1dB, but on a bandwidth perspective, the Accuphase is completely transparent.

----

Oh, yes, another measurement that you can use to compare with other devices. It is the THD+N ratio vs frequency, with an extended bandwidth to capture all distortion and noise components up to 90kHz:

View attachment 492123

In 1982, I'm sure nobody thought about such a punishing test. But the Accuphase stays at 0.001% (-100dB) which is much more than reasonable.

----

The below IMD SMPTE sweep vs input level is not comparable to the same test from Amir, because it is excluding noise:

View attachment 492127

The trace shows a sweet spot at 1Vrms, and note I was at unity gain on this test. This last test confirms that the Accuphase is free from any type of distorsion.

----

Other measurements (not shown):
  • Input clipping at just above 20dBu (7.8Vrms).
  • Output voltage clipping: above 10Vrms (I can't measure more).
  • Dynamic Range (CCIR 2k weighted): from 100dB at unity gain to 120dB at max gain.
  • IMD AES (18kHz + 20kHz 1:1) : below -120dB from unity gain and above!
----

The line stage of this preamplifier offers staggering performances, in today's world, and they were absolutely unnecessary at the time, since no source was anywhere close to these performances. I guess the C-280 was pleased to see higher resolution devices join his game, but had to wait 5 long years for that (with the Accuphase DP-70 here below). And even so, it had headroom for more than that. Incredible.

View attachment 492289


The Accuphase C-280 is the pure definition of a preamplifier: straight wire with gain.


Accuphase C-280 - Measurement (Phono MM)

Spoiler Alert: Ok, so, that thing has been designed to be a Phono preamp, before everything else, I tell you. Let's see what you have to tell us, Mister HEAD AMP:

View attachment 492315

For what follows, I will be talking only MM simply because my poor Topping D50III (used as the generator for these tests) is not linear enough to create a decently silent 0.5Vrms output that would suit MC input. So I measured only the noise of the Topping in that case. Boring. With MM, I got results I can use, since the noise floor was low enough to get good results.

Let's start with the standard SINAD, again not comparable to what Amir usually does and I'll explain why:

View attachment 492133

This is the signal as it comes out from the Phono preamp, meaning I did not compensated the RIAA curve. The results are staggering, I mean we are close to CD Audio!

Now, let's correct the RIAA curve, with the software, to simulate how a record would be created, with the opposite curve:

View attachment 492134

Ok, we lost 12dB because you see the noise after 1kHz being higher, which is what the RIAA curve correction does. Now this is also extremely good result, no cartridge offers that linearity. Look at the distortion nearly absent, and you know what? It's the one of the Topping that is providing the test signal!

Why 40mVrms input when Amir uses 5Vrms for this test? For two reasons:
  1. The Topping does not provide a good enough signal at 5mVrms, simple.
  2. Because some dynamic cartridges (eg: Shure M44-7 - 9mVrms for 5cm/sec), together with over-cut records, would be reaching a speed velocity of 30cm/sec, meaning they'd be at or beyond 60mVrms.
And to add to that, I'm using a 40dB gain amplification, as this is very common, and so with 40mVrms at the input, we get 0.4Vrms at the output, for the above test.

----

Next important set of measurements for a phono preamp is related to the above. It is important to know at what point it will clip, depending on the frequency. We need a good headroom, and all ancient phono preamps where known to have very good headroom. That's measured with a sweep of THD vy input level, at different frequencies. Let's check what our big bo(y)x has to say:

View attachment 492143

When I first saw the results of the sweeps, they made me laugh. The Accuphase clips past 300mVrms at 1kHz. That is giganticnormous :eek:
And look, at 10kHz, it does not reach 1% distortion with 2.5Vrms input!!!

Not only that, but the level of distortion is very low, and again we actually see the one of the Topping D50III, one of the best in class most linear DAC in existence.

The Accuphase will never break a sweat - it makes the laws of audio look lazy.

----

Ok, bandwidth, as we need to check the respect of RIAA curve:

View attachment 492148

Accuphase said "guaranteed +-0.2dB", I see below +0.1dB. Well done. Don't forget, 40+ years old...

----

Oh, yes, for the fun, as @amirm likes the below measurement. It is a sweep of THD only (no noise) with an extended bandwidth up to 90kHz to capture distortion at high frequencies too:


View attachment 492153

I did the above with two different input levels (5mVrms and 10mVrms), at respectively 52dB and 40dB. Well, the distortion we see does not come from the Accuphase, but one more time, you know...

The phono stage of the Accuphase C-280 is outstanding.


Conclusion

I've been preparing this review for weeks, spent countless hours performing measurements, and so many more to prepare the script and write this review. It was a personal investment, an adventure worth every single hour spent on this fantastic piece of engineering.

I initially thought it was unfair to torture this old device as we'd do on modern ones. But my friend convinced me to go for it. And oh boy...

This isn’t a preamplifier, it’s an artist in disguise. And it knows about architecture: I can't resist to share one last picture:

View attachment 492160

Yes, certainly, some modern devices can beat it, but you have to search hard for them. And what will remain of them in 40+ years? I'd be curious to know, but I'm unlikely to be around, considering my age and genes.

At the end of the day, Accuphase said the specs were guaranteed… and they could have added "for at least 40 years".

I hope you enjoyed this review as much as me writing it.

Happy weekend!

Flo
Click to expand...
I really loved your review, and happily agree about the beauty of the C280
 
Very sexy unit and performance to match.
Kudos to Accuphase for engineering such a gorgeous and performant piece of kit.
And cheers to the OP for the incredible amount of work and love that went into this technical review!
 
Awesome review, thank you very much!!

The other day I watched this video about their factory

 
You must log in or register to reply here.

Similar threads

NTTY
Denon PRA-S10 Review (Preamplifier)
2
Replies
31
Views
12K
lini
lini
NTTY
Rotel RC-03 Review (Preamplifier)
2 3
Replies
42
Views
11K
OldManMatt
OldManMatt
D
Chinese accuphase clone comparison video
6 7 8
Replies
148
Views
19K
Agapetos
A
Jokke
Accuphase E-3000
2 3 4
Replies
77
Views
10K
pablolie
pablolie
aamwgm
Using an Accuphase E-202 in today's age. Am I missing something?
2 3 4
Replies
79
Views
7K
aamwgm
aamwgm
Back
Top Bottom