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Topic: Debunking The Pcavtech Turntable Test (Read 5570 times) previous topic - next topic
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Debunking The Pcavtech Turntable Test

Hi everyone,

I have to take the opportunity to publicly discredit the following test:

http://www.pcavtech.com/play-rec/rega-2/index.htm

Please see the following:

http://www.audioasylum.com/audio/vinyl/mes...ges/165204.html

(except for the "pink noise vs. white noise" I agree with the author... but who knows what equipment was used to generate this pink noise, and what QC used in cutting the record?  It wasn't intended for testing frequency response, just a general guide!)

Some verification of the above claims:

http://www.tnt-audio.com/accessories/hfnrrdisc_e.html

Please do not use the "Rega 2" test at PCAVTech anymore as an example of a "real" test of vinyl's potential (or lack thereof), unless it is performed again under controlled and verifiable conditions, using a proper test methodology of some kind.

In the CD age, this whole topic might seem moot to some people... but vinyl is enjoying a resurgence in popularity, and there's a large back-catalog of music never released on CD -- in other words, either you locate a copy of the record or you can't hear it, period. 

Comments are welcome... flames are OK too if they're civil .

Debunking The Pcavtech Turntable Test

Reply #1 –
Quote
Please do not use the "Rega 2" test at PCAVTech anymore as an example of a "real" test of vinyl's potential (or lack thereof), unless it is performed again under controlled and verifiable conditions, using a proper test methodology (test record with frequency sweeps, maybe -- perhaps using an oscilloscope rather than a sound card).

As to my link to PCAVTech report, this  was only intended to show frequency response of vinyl. I've read on detail the TNT Audio link, and they say:

"Track two and three are sweeps from 25-5"

I guess they mean 25 KHz to 5 Hz, but I can be wrong. Can you verify this? If it was so, it is a good way to measure frequency response of vinyl, although it is still dependant on how was the signal cutted. BTW, this is another signal on how difficult is to achieve good frequency response accuracy on vinyl, because it depends on too many factors.

As to THD figures, they are measured with a 1 KHz tone, not the overloaded 300 Hz tone. This 300 Hz tone is used to measure "jitter", or in this context, wow and futter. I'd say that the fact that this tone is overloaded, at first doesn't have influence in the "jitter" measurement.

On the other side, this test can have some flaws. Maybe the turntable is not top-quality, and also this kind of tests for vinyl are very dependant on how the test signals were cutted into the record, and how well the turntable is set up. However, these problems don't exist on cd. Measurements on cd are indicative just of the quailty of the player, and don't depend on any other things (provided that the test signals are properly generated, not a difficult thing).

Also, recording the output of an audio device with a good 24 bit sound card is a perfect way to make measurements of audio signals, provided that the sound card has better performance than the device at test. This is true specially in the case of vinyl. Also, a digital oscilloscope is not more than an embedded good soundcard.

Debunking The Pcavtech Turntable Test

Reply #2 –
Quote
As to THD figures, they are measured with a 1 KHz tone, not the overloaded 300 Hz tone. This 300 Hz tone is used to measure "jitter", or in this context, wow and futter. I'd say that the fact that this tone is overloaded, at first doesn't have influence in the "jitter" measurement.

Can you explain the caption at the top of this graph, in the title bar?  This is the graph used in the THD test:

http://www.pcavtech.com/play-rec/rega-2/grado-SNR.gif

What's the reference to "300Hz" displayed there, and why the big peak at 300Hz?

See the other peaks at higher frequencies?  Probably distortions caused by heavy overmodulation and subsequent mistracking, not by the turntable or some flaw in vinyl reproduction.

There's a 1KHz tone on the "old" HFN test record (assumed to be the one used in the test, since it's been around longer than a couple months).  It includes a sweep from 16Hz to 6Hz (inaudible) with a 1KHz "pilot tone" -- intended to test arm/cartridge vertical resonance (at some frequency, the tonearm vibrates up and down signaling the resonant frequency of the arm/cartridge related to cartridge compliance/tonearm mass).  This test was intended to determine tonearm/cartridge matching, not wow & flutter!  Maybe I missed something, but I didn't see any reference to it anyway on the Pcavtech.com page -- none.

I've got the HFNRR test record sitting in front of me at this moment, KikeG.  Please tell me if I missed something.

Debunking The Pcavtech Turntable Test

Reply #3 –
I can't believe it is a pink noise, a pink noise sarts at 0 db at 20 Hz, and decrease to -30 db at 20 kHz. Anyway, the frequency response is the one of the Grado Cartridge, the turntable play little to no role in the frequency response.

Debunking The Pcavtech Turntable Test

Reply #4 –
Quote
I can't believe it is a pink noise, a pink noise sarts at 0 db at 20 Hz, and decrease to -30 db at 20 kHz. Anyway, the frequency response is the one of the Grado Cartridge, the turntable play little to no role in the frequency response.

Would you like a scan of the back of the album cover listing the tracks?

And what Grado cartridge is this?  Grado has been making cartridges since 1953 .  Their current lineup includes a price range from U.S. $40 to $2,500.

When you talk about "the turntable," what do you mean?  Exclusive of the cartridge... how could it play music?  A turntable is not separable into parts, except arbitrarily -- it's an integrated unit.  Cartridge/tonearm/plinth/platter/motor, these all act in concert as a single unit, to determine 'performance'.  Welcome to analog... 

Debunking The Pcavtech Turntable Test

Reply #5 –
Quote
Can you explain the caption at the top of this graph, in the title bar?  This is the graph used in the THD test:

Ehm... You're right, I didn't pay enough attention to the graph, since the report says THD@1KHz, I gave a quick look (I'm at work) and (incorrectly) though it was a 1 KHz tone, the one they refered to at the TNT Audio page. Yes, this is the 300 Hz tone, and seems that not the proper signal to test THD, as you pointed out. I apologize for that.

As to the sweep signals for frequency response, well, looking at the report it seems that the signal used for frequency response is a white noise, and if as the person at AA says, there's none, well, I don't know how did Arny measure it, and I don't know if it's reliable.

So, OK, I won't use this link anymore as proof of vinyl performance.

Quote
Please tell me if I missed something.

It seems that you didn't.

However, as you'll have noticed, I'm quite stubborn  , and I still think that technical performance of vinil is inferior to the one of CD. Hey, no problem for discussing things. 

Debunking The Pcavtech Turntable Test

Reply #6 –
Quote
However, as you'll have noticed, I'm quite stubborn   , and I still think that technical performance of vinil is inferior to the one of CD. Hey, no problem for discussing things.  

You might be right (I don't claim to agree or disagree, having no hard evidence).  But I think the Pcavtech test was done so casually (lacking attention to detail) that it's worthless.  Even the information at R3mix.net is more accurate and justified than this nonsense.

Edit -- I suppose before Arny chimes in (?) I should repost this statement from the website displaying the test:

"All material on this page is Arny Krueger's personal opinion, provided for entertainment purposes only. See web site disclaimer for details"

Debunking The Pcavtech Turntable Test

Reply #7 –
fewtch: don't wanna start a vinyl vs all war here, but it seems to me that the main problem of vinyl is the fact that you need some sort of training and lots of money to effectively use a turntable.

I have heard BEAUTIFUL music come out of a system like this. But the guy that did it spent TONS AND TONS of money on his system. Furthermore, he spent lots of time tuning it so that it would sound just right. On the other hand, I can buy any CD player, a decent receiver and good speakers and get the same sound. Notice that I am not saying better, since this is entirely objective.

It is irrevelant to say if one test is better than any other. We all know the limitations of old records. We all know that CDs are better on paper, and for the most part on practice as well. The people that like records now are the ones that will like them for the rest of their lives, just like the people that claim the moon landing was a hoax.

Also, you are SO right about the albums that are out on vinyl but not out on CD. My personal hunt is for John Payne - "Ride The Storm". Came out in 1988. The problem is, once I find it, I have to look for someone with a GOOD deck to play this on, so I can record it on my soundcard. And I dont know where the guy above went (he was a friend of a friend). I imagine that someone could set up a small business that transfers LPs to CDs. Maybe using that laser turntable or something...

Debunking The Pcavtech Turntable Test

Reply #8 –
Quote
Even the information at R3mix.net is more accurate and justified than this nonsense.

Ouch - low blow...

Debunking The Pcavtech Turntable Test

Reply #9 –
LoKi128: LP2CD.com does laser turntable to CD transfers. I have no experience dealing with them so this is not an endorsement, caveat emptor, etc. Quite a few links returned on  a Google search for LP to CD as well 
No, I am Jack's complete lack of surprise.

Debunking The Pcavtech Turntable Test

Reply #10 –
Quote
fewtch: don't wanna start a vinyl vs all war here, but it seems to me that the main problem of vinyl is the fact that you need some sort of training and lots of money to effectively use a turntable.

I have heard BEAUTIFUL music come out of a system like this. But the guy that did it spent TONS AND TONS of money on his system. Furthermore, he spent lots of time tuning it so that it would sound just right. On the other hand, I can buy any CD player, a decent receiver and good speakers and get the same sound. Notice that I am not saying better, since this is entirely objective.

It is irrevelant to say if one test is better than any other. We all know the limitations of old records. We all know that CDs are better on paper, and for the most part on practice as well. The people that like records now are the ones that will like them for the rest of their lives, just like the people that claim the moon landing was a hoax.

Also, you are SO right about the albums that are out on vinyl but not out on CD. My personal hunt is for John Payne - "Ride The Storm". Came out in 1988. The problem is, once I find it, I have to look for someone with a GOOD deck to play this on, so I can record it on my soundcard. And I dont know where the guy above went (he was a friend of a friend). I imagine that someone could set up a small business that transfers LPs to CDs. Maybe using that laser turntable or something...

LoKi, the point I'm trying to make is that the test referred to in this thread was conducted improperly and without regard to the format in question (which I think fits well with the philosophy of this board -- accuracy and truth about audio). 

All of what you say is true in regards to vinyl (it's no longer a widely used or sold consumer format), but it doesn't change the fact of a badly done test, and people who may use such a "test" to argue that vinyl is inferior (I'm not singling anyone out).  If people want to argue that then great, but do it using a proper test of some kind... this one is like using the Blade encoder at 96kbps as "proof" that MP3 is an unlistenable format. 

Yes, it can take more money to get a good vinyl setup... unless you do a lot of research and are willing to buy vintage and learn to set things up properly -- in that case, it really doesn't cost any more than a CD player does (unless you mean a CD walkman or something).  As for records, you can get them for $0.50 apiece if you know where to look.  Of course, most people don't want to bother, and I wouldn't ask anyone to who doesn't want to.  In fact most of what I do is transfer vinyl to CD-R's (and lossy audio formats) so I don't have to bother with spinning records -- it's really a pain in the tail.  But a lot more people listen to vinyl than you probably think, and most are in their 20's or 30's, not 50's & 60's.

P.S. there are a lot of businesses (Internet based and otherwise) that transfer LP's to CD, but they tend to be rather expensive.  Worth it if you only have a few records to transfer, maybe.

Debunking The Pcavtech Turntable Test

Reply #11 –
Quote
Would you like a scan of the back of the album cover listing the tracks?


After a second look, it matches very well a pink noise (0 to -30 db) without the RIAA equalisation (-20 to +20 db, leading to -20 to -10 db as a result, as we can see on the picture, if we interpolate to 20 Hz, here affected by the warping of the vinyl that shakes the cartridge around 8 Hz)

Quote
When you talk about "the turntable," what do you mean?  Exclusive of the cartridge... how could it play music?  


I can't and therefore have no frequency response, I think we agree on this point. I'd just wanted to add that, if I'm not mistaken, a given cartridge has the same frequency response on any good turntable.

Quote
A turntable is not separable into parts


I've always seen turntables sold without cartridge, and cartridges without turntables, as amplis and speakers. But the Rega Planar 2 is rather sold with a Rega Bias cartridge.

Debunking The Pcavtech Turntable Test

Reply #12 –
Quote
Quote
A turntable is not separable into parts


I've always seen turntables sold without cartridge, and cartridges without turntables, as amplis and speakers. But the Rega Planar 2 is rather sold with a Rega Bias cartridge.

Well I meant, taken as an analog device that plays music, you can't isolate one part of it and say "this is mostly all that matters."  If the tonearm resonates, it will introduce distortion... if the motor rumbles it will induce distortion, if the plinth echoes when you tap it, it will cause distortion (acting like a big microphone). 

Analog playback is an uphill battle against various types of distortion (I'm the first to admit), but you can't correctly say "only the cartridge plays the music."  Frequency response -- true (given correct setup -- which btw is unknown in the rega2 test), but how will you measure it properly with distortions & resonances induced by other things?

Debunking The Pcavtech Turntable Test

Reply #13 –
I haven't taken the time to properly read through this thread, and unfortunately I probably won't anytime soon either, but has anyone contacted the webmaster of the site about this?  You do know that one of the guys behind that page is Arny Krueger, right?  This is the guy who came up with pcabx and who has been quite a staunch advocate of objective testing on the internet.  From what I have read from him, he's quite knowledgeable about audio and is usually right in what he posts about.  As I said, I haven't really read through this thread, and I'm no vinyl buff anyway so I probably couldn't contribute much (and you could be right in your claims), but at the least I think it would be productive to email this guy and let him respond to some of what you're saying.

Debunking The Pcavtech Turntable Test

Reply #14 –
Email to Arny is likely to be ignored.  The best way to get a response from Arny is to post a message on rec.audio.high-end (note that this is a moderated newsgroup, so you need to use a real email address in your post), and put something like pcavtech in your subject line so he reads it.

ff123

Debunking The Pcavtech Turntable Test

Reply #15 –
Offtopic.

Are the soundcard comparisons on the Pcavtech website still pretty accurate?
I bought a Santa Cruz 2 years back as my main card since it seemed to clearly outperform all the Creative cards.

Debunking The Pcavtech Turntable Test

Reply #16 –
Quote
I haven't taken the time to properly read through this thread, and unfortunately I probably won't anytime soon either, but has anyone contacted the webmaster of the site about this?  You do know that one of the guys behind that page is Arny Krueger, right?  This is the guy who came up with pcabx and who has been quite a staunch advocate of objective testing on the internet.  From what I have read from him, he's quite knowledgeable about audio and is usually right in what he posts about.  As I said, I haven't really read through this thread, and I'm no vinyl buff anyway so I probably couldn't contribute much (and you could be right in your claims), but at the least I think it would be productive to email this guy and let him respond to some of what you're saying.

Dibrom,

I did Email him, and referred to the Audioasylum post (provided the link) as something that might be of interest -- he never responded.

To be honest, I don't want to bother posting something on Usenet to "get his attention."  From everything I've heard, it's likely to be confrontational -- and what's the point of that?  I want to present facts (and hopefully I've made my case in this thread for anyone who wants to investigate), not get into an argument.  It doesn't seem worth the time or energy to bother with this guy, but it does seem very much worth the time/energy to debunk obviously sloppy and inaccurate testing, even if that testing involves a topic that only interests a few people. 

If anyone else is interested enough, perhaps it will come to his attention eventually, but dealing with arrogance is not my idea of a good time.  I've been through that trip already.

fewtch
 

Debunking The Pcavtech Turntable Test

Reply #17 –
Quote
Are the soundcard comparisons on the Pcavtech website still pretty accurate?

Arny is usually right, but that doesn't exclude that he can occasionally make an error. As to his vinyl measurements, it seems that they are just some "hidden" preliminar (but somehow old) measurements, and have not a direct link from his main page.

As to other measurements, I think he's usually right. The bad thing about his page is that it is very rarely updated, and some measurements and data are quite old.

His measurements on the Santa Cruz give very similar results to the ones I've done on mine.