Accuphase digital preamplifiers (DC-300, DC-330)

[meltemi]

Originally Posted by Barsur

Last weekend, we did do a quick "light" blind test between DC 300, C 290 and C 2420.
The rest of the equipment was Accuphase DP 510, A 70 and Magico S1. Two people listened blind (my son and a member of the Berliner Philarmonie, who have better ears than my ears and I switched the cables).

I have one question: what cables did you use?

[nvp]

Martin (aka Brasur), I do not doubt your findings, however, it seems to me that you are over-interpreting them. That is, what you have found applies only in the context of your room, speakers and music. As such your results can not be generalised (even though they may be valid for many people).

One very important limitation in your tests is the speakers which have (very) limited dynamic capabilities. This limitation will prevent you from drawing correct conclusions. The difference between C-24xx and C-28xx pre-amps can easily be heard when playing music exhibiting very sudden and very large dynamic variations. When using a speaker-amp combo capable to properly deliver dynamic variations one will find that the C-28xx pre-amps will sound significantly louder and faster than the C-24xx pre-amps. While the music will not necessarily sound constricted via C-24xx pre-amps, the difference between the soft and loud notes will be significantly smaller on the C-24xx units than on the C-28xx units. These differences will become even larger when using the C-38xx units.

I have mentioned more than once here that (with the C-3800 pre in my system) the meters of my A-65 amp show variations of 300-fold on certain CDs. While I did not do any rigorous tests, I do not recall to have seen such large power variations when I had the C-2810 pre-amp. With the C-2810 pre variations between 150- and 200-fold were not unusual. Now, differences in loudness caused by a 200-fold and a 300-fold increase in power are easily audible and measurable with a dB meter. (I personally appreciate systems with such dynamic capabilities - for me they sound more real.)

I hope my argument above will be received as meant, i.e. constructed criticism.

Paul

[Barsur]

Originally Posted by meltemi

I have one question: what cables did you use?

Speaker cables are Kimber 8 TC All Clear, interconnects cable are JPS Superconductor.

Best regards

Martin

[Barsur]

Originally Posted by nvp

Martin (aka Brasur), I do not doubt your findings, however, it seems to me that you are over-interpreting them. That is, what you have found applies only in the context of your room, speakers and music. As such your results can not be generalised (even though they may be valid for many people).

One very important limitation in your tests is the speakers which have (very) limited dynamic capabilities. This limitation will prevent you from drawing correct conclusions. The difference between C-24xx and C-28xx pre-amps can easily be heard when playing music exhibiting very sudden and very large dynamic variations. When using a speaker-amp combo capable to properly deliver dynamic variations one will find that the C-28xx pre-amps will sound significantly louder and faster than the C-24xx pre-amps. While the music will not necessarily sound constricted via C-24xx pre-amps, the difference between the soft and loud notes will be significantly smaller on the C-24xx units than on the C-28xx units. These differences will become even larger when using the C-38xx units.

I have mentioned more than once here that (with the C-3800 pre in my system) the meters of my A-65 amp show variations of 300-fold on certain CDs. While I did not do any rigorous tests, I do not recall to have seen such large power variations when I had the C-2810 pre-amp. With the C-2810 pre variations between 150- and 200-fold were not unusual. Now, differences in loudness caused by a 200-fold and a 300-fold increase in power are easily audible and measurable with a dB meter. (I personally appreciate systems with such dynamic capabilities - for me they sound more real.)

I hope my argument above will be received as meant, i.e. constructed criticism.

Paul

In my humble opinion, you are absolut right. And we mention this always in our amateur internet page (Home - www.amp-shootout.com). The results apply only in the context of my room, my speakers and which music do I use. I forgot to mention this in my original quote.
Normally we use for the comparison Linn 242 mk3 speakers which have higher dynamic cabilities as Magico S1. But on the other hand Magico S1 are very revealing speakers. Normally we do our "full" blind test with three different SPL levels. For example: 75 dB, 85 dB and 100 dB SPL.
When I said we listen with 80 dB SPL, means I measure everything with a 1Khz sinus tone from a Test CD, with real music than the SPL change for example between 50 dB to 90 dB.
What you mentioned with the "300-fold" depends in my humble opinion extremly which kind of music you are listening. When we heard Wagner without words "Siegfried Trauermarsch" I could see "1.000-fold" on the A 70, from 0,01 Watt to 10 Watt in miliseconds.

Best regards

Martin

[nvp]

Martin (aka Brasur), if one performs incorrect/incomplete experiments chances are he/she will obtain incorrect answers. The point I made in my previous post is that the test you have performed is unable to reveal the dynamic capabilities of the three pre-amps considered. Since (IMO) one of the main difference between entry-level, mid-level and top-level Accuphase units (e.g. pre-amps and cd players) is their dynamic capability (i.e. a characteristic that your experiment does probe), I argue that it is crucial to test this parameter before proclaiming the compared units indistinguishable.

Of course, it is possible that the three pre-amps you have tested have similar dynamic capabilities. In that case, your conclusion (i.e. the differences between them is minimal if any) will be significantly more accurate. However, since your experiment does not provide accurate information about this important characteristic, your over-confident comments (cited below) are not justifiable.

Originally Posted by Barsur

Very good Quote from you and this confirms all the blind test which we did so far. I am always laughing , when I read from people about the "big, noticeable differences".

PD: And if somebody can hear (9 out of 10) in a blind test the difference of two CD Player (for example I have the Accuphase DP 510 and the Mcintosh MCD 301), I will give him a CD Player as a present...

I should also say that your results are certainly not meaningless. They show clearly that if one listens to music without large dynamic variations, or if one is not willing to buy speakers capable of delivering large dynamic variation, then he/she has no reason to invest in the top Accuphase pre-amps (and cd players). I should also say that it is very clear to me that it is not at all easy (in fact it is almost impossible) to perform experiments as the one you have performed in a manner that is 100% rigorous. Even if one manages to take good care of the critical parameters (e.g. speakers, room, amps, test songs, experienced listeners), one still has to test each unit in several areas and at the same time keep the judges (i.e. the experienced listeners) alert, enthusiastic and unbiased during the period of the entire test (i.e. over a rather long period of time). Therefore, I will not be complaining about other relevant tests/parameters that have been neglected in the experiment.

Paul

[nvp]

To substantiate my argument above I have done a basic experiment tonight. Since I do not have an additional Accuphase pre-amp or cd player, I have compared the dynamic capability of my Accuphase DP-720 player to that of my Sony BDP-S790 Blu-Ray player.

This comparison (i.e. a €17k dedicated music player vs. €200 video player) might seem ridiculous, however, the reality is that with quite a few popular CDs (e.g. Diana Krall’s The girl in the other room or AC/DC’s Back in Black) I can not distinguish the two players. When using such CDs as test material, my conclusion is very similar to the one expressed by Brasur above: most people (if any) will not be able to distinguish these two players. It is important to realise, however, that this is not the whole story! For example, if one compares the two players using music that exhibits large dynamic variations the difference between the two players is very large and can be heard by anybody without any effort.

Here are the details of the test I have performed:

Main system (unchanged during the test): C-3800 -> Accuphase A-65 -> Avantgarde Uno speaker (everything was connected to the PS-1220 power supply)

Compared units: DP-720 vs. BDP-s790 Sony (the 2 players were connected to the C-3800 pre alternatively via the same Accuphase ASL-10 interlink cable)

CDs:
1) Audio Physic music CD: Track 16, Die Schlacht bei Vittoria, op. 91 1813 / L. van Beethoven. (The relevant passages for this test can be found between minutes 4:00 and 4:40.)

2) Nordost system set-up & tuning disc: Track 1, Channel check (I used this as a basic check to verify that the two players play at the same volume, i.e. 63 dBs. )

Additional note:
- No unit has been turn off during the test (e.g. when connecting/disconnecting the tested players).
- The interlink cable was connected to the CD input of the C-3800 all the time. The players were connected alternatively at the other end of the interlink (duh...).
- Volume setting of C-3800: -45 dB
- Gain setting C-3800: 18 dB
- Gain setting A-65: -12 dB
- A-65 meters were set on infinite
- The DP-720 and BDP-s790 players were also connected to the PS-1220 unit.


RESULTS:
Maximum output power indicated by the A-65 meters:
---------------------------------------------------------------
- DP-720: 0.055 watt left channel
- DP-720: 0.063 watt right channel
----------------------------------------------------
- BDP-s790 Sony: 0.025 watt left channel
- BDP-s790 Sony: 0.027 watt right channel
----------------------------------------------------
difference: ~ 0.025 watt

DISCUSSION:
Given the extreme sensitivity of my speakers (105 dB) the small difference (~0.025 watt) recorded by the A-65 power indicators was clearly and easily audible. However, while in theory a power variation of 0.025 watts should induce a SPL variation of 3.7 dB (with speakers having 105 dB sensitivity), my dB meter has recorded for the most part significantly larger SPL differences between DP-720 and the Sony blu-ray player, i.e. between 6 and 10 dB. (It is possible that the additional energy generated by the DP-720 player was enough to excite some room modes.) Because the difference between the two players was so significant I am tempted to say that one will be able to hear the difference between the two players via a mobile phone.

I hope this little and very rudimentary experiment has demonstrated that:
1) 2 units can sound the same when improperly tested.
2) The same 2 units can sound very very different when "properly" tested.

With this I rest my case.

Paul

p.s. of course, anyone is welcome to perform this simple experiment to convince himself/herself of the validity of the "results" I have reported above.

[Barsur]

Originally Posted by nvp

To substantiate my argument above I have done a basic experiment tonight. Since I do not have an additional Accuphase pre-amp or cd player, I have compared the dynamic capability of my Accuphase DP-720 player to that of my Sony BDP-S790 Blu-Ray player.


Here are the details of the test I have performed:

Main system (unchanged during the test): C-3800 -> Accuphase A-65 -> Avantgarde Uno speaker (everything was connected to the PS-1220 power supply)

Compared units: DP-720 vs. BDP-s790 Sony (the 2 players were connected to the C-3800 pre alternatively via the same Accuphase ASL-10 interlink cable)

CDs:
1) Audio Physic music CD: Track 16, Die Schlacht bei Vittoria, op. 91 1813 / L. van Beethoven. (The relevant passages for this test can be found between minutes 4:00 and 4:40.)

2) Nordost system set-up & tuning disc: Track 1, Channel check (I used this as a basic check to verify that the two players play at the same volume, i.e. 63 dBs. )

Additional note:
- No unit has been turn off during the test (e.g. when connecting/disconnecting the tested players).
- The interlink cable was connected to the CD input of the C-3800 all the time. The players were connected alternatively at the other end of the interlink (duh...).
- Volume setting of C-3800: -45 dB
- Gain setting C-3800: 18 dB
- Gain setting A-65: -12 dB
- A-65 meters were set on infinite
- The DP-720 and BDP-s790 players were also connected to the PS-1220 unit.

Dear Paul, thanks a lot for the detailed describtion of your test. In my humble opinion, you missed the most important point in a blind test. You have to listen to the different equipment with exactly the same SPL. This is the most important topic!!! For that reason I called the blind test between DC 300, C2420 and C290 a "light" blind test, because I couldn´t get the three preamps on the same SPL (C 290 had 0,2 dB more SPL).

Which methods do you have to achieve the same SPL?! We have two methods, the best is I measure the output line voltage (I have a HP measurement equipment). This is the most exact way to do it. Or seconed method, which I use for a "light" blind test, I take a test CD with a 1khz sinus tone and measure with a microphone the SPL from the different equipments, that at the end you have the same SPL Level (normally we allow 0,1 dB difference).

What you heard in your test is only the differnt output voltage from the Accuphase DP 720 against the Sony BluRay Player because according to your Quote you let the preamp with -45 dB Output Level.
But CD Players have different output Level.
I give you some examples:
I had the Accuphaese DP 700, there I measured an output voltage of 2,5 Volt (Hifi & Records measured 2,45 Volt).
The guy from the Berliner Philarmonie has the Accuphaese DP 720, there we measured an output voltage of 2,7 Volt (Hifi & Records measured 2,63 Volt). So this is a very "loud" CD Player!
I have the Accuphaese DP 510, there I measured an output voltage of 2,5 Volt (no Hifi & Records measurements).
I have also the Spectral SDR 4000, there I measured an output voltage of 1,3 Volt (Hifi & Records measured 1,22Volt). This is a CD Player which is not very loud.

If you want to do a comparison between these CD Players you have to level them with your preamp to get the same SPL for a fair comparison.

I think, I upset you with my words "I am laughing...if I read about big differences". I want to apoligize for this.
My english is a little bit bad, for that reason this weren´t the right words.
What I wanted to say is: I am a little bit surprised if people talk about BIG differences from amps and CD player.
In my humble opinion:
you can hear sound differences from speakers and rooms
you can hear "sublte" sound differences from amps
you can hear "almost" no differnces at all from CD Players.

And don´t missunderstand me; I love this hobby. According to one of my dealers I am one of the biggest collectors in Germany with ca. 400 High End Units which I own.

Best regards

Martin

[nvp]

Dear Martin (aka Barsur),

the volumes of the two players have been "equalised" at 63 dB. To achieve this the level meter of the DP-720 was set at -3 dB. In my initial draft the numbers in the results section were organised like in a table. Because this “table” was not conserved after pasting everything in the AA page I had to edit my post a few times. It seems that when doing this I have deleted by mistake the crucial information about the DP-720 level setting (which was situated one line above the “RESULTS section”). I am sorry for this silly typo, it was 01:00 hours...

I could easily repeat this test and equalise the volume from the pre-amp and thus leave the DP-720 level to 0 dB (which probably will be slightly more "precise”). However, since I "compare" cd player my results will, in the end, neither confirm nor infirm your conclusions about the three Accuphase pre-amps - they may have similar dynamic capabilities. All I am arguing is that you can not proclaim the three pre-amp identical unless you test properly their dynamic abilities. As I have mentioned before, IMO opinion this characteristic is a crucial difference between various Accuphase pre-amp from different classes.

Paul

p.s. I refer to you as "Martin (aka Barsur)" because there is a 2nd Martin here (aka meltemi)

[vinod_david]

Wow, very nice discussion. Very informative indeed.

[nvp]

Barsur (also Mattia), I have repeated my experiment and this time with some very unexpected results (at least for me). Basically, I was not able to reproduced the result I have obtained yesterday. In fact, I have repeated the experiment several times and each time I have obtained (slightly) different values!

To pinpoint the problem I have changed the setting of the A-65 meters from infinite to the “1 second” setting. I have recorded repeatedly the indications of the A-65 meters during a 10 second long music passage that exhibits rather large dynamic variation without changing any settings in system. To my dismay the A-65 showed each time slightly different values. For example, if I was back-forwarding 30 seconds before the beginning of my reference passage the meters indicated power variations from 0.005 to 0.063 watts (during the reference passage), whereas if I was back-forwarding 20 seconds the meters indicated power variations from 0.005 to 0.048 (during the same reference passage).

The funny thing is that this type of results have convinced me a long time ago, while still a student, to pursue a theoretical/computational (as opposed to experimental) path as a physicist. Already then it was clear to me that it is much easier (at least for me) to reproduce computational results than experimental results. Even funnier, is the fact that about 6 months ago I have decided that maybe I should try my hand again in the lab and, as such, I have spent €200k of my research money on a spectrometer that should arrive next week. Hopefully my PhD student will be better than me at this.

Nonetheless, do you guys have any reasonable explanations for these strange results?

I look forward to hear your thoughts!

Paul