I'm not sure what you mean Raul. Could you restate your last comment?
A Few Turntable Measurements using the RPM Android App
I found this Android phone app for TT rotation. Phone is Pixel 4a. Thought I'd try this app out. I'm skeptical of these phone apps. Accuracy is always an issue.
I have four tables. I took 5 readings for the first table in order to see what the repeatability is. The "absolute" RPM, RPM peak to peak, and 2 sigma range readings were very, very repeatable. Consequtive RPM readings differed by a max of 0.01 RPM. Two sigma varied by 0.01% ( 2 sigma means that 86% of the readings were within the stated value). I personally would use 3 sigma, but that's a personal quibble.
I've measured all four of my tables. I am very certain that the results are very repeatable. I measured with no LP, LP rotating, LP on and Stylus engaged, and phone offset from center. RPM was the same for all cases, The 2 sigma showed a 0.01% rise (really small). The reading at the edge of the LP was different. And scary to do!
Here's the results:
1. DD-40 #1, RPM = 33.32, 2 sigma = 0.07% (63 dB)
2. DD-40 #2, RPM = 33.27, 2 sigma = 0.09% (61 dB)
3. Acoustic Signature WOW XXL, RPM = 33.17, 2 sigma = 0.10% (60 dB). This varied 0.02% from reading to reading (after running the table for 10 minutes, this noise diminishes), but the 2 sigma stayed the same.
4. Denon DP-57L, RPM = 33.25, 2 sigma = 0.02% (74 dB).
I then went back to DD-40 #1. Using the RPM app, I set the mean speed to be 33.25. The strobe on the table was slowly moving! I checked against the strobe on the Cardas test LP and yes, the RPM speed accuracy was wrong. I reset TT speed using the strobe. The RPM app measured 33.23 again. I must conclude that although the RPM app is very repeatable, the absolute accuracy is not. The wow result (2 sigma variation) remains the same.
I measured the 45 RPM on DD-40 #1. RPM = 44.91, 2 sigma = 0.05%, so the 45 RPM is fairly accurate and the 2 sigma is lower.
This app makes no distinction between wow and flutter. It's all reported in the wow reading (wow and flutter are the same thing by nature, the only difference is the frequency range).
I'm surprised by the poor performance of the WOW XXL table. This a modern, belt driven table, with a massive platter. It is 5 years old. There's no way for the user to adjust the RPM. The variation in the speed is similar or slightly higher than the 40+ years old Micro Seiki DD-40 tables, which don't have crystal oscillator driven speed control. The WOW XXL takes about 10 minutes before the very high frequency variations settle. Now, I don't know much about the internal workings of the app. Helpful would be better accuracy (or the AC frequency in my house is not 60 Hz). Bandwidth is not reported.
The DP-57L performance is outstanding!. This TT was made in the 80s. And the DD-40 tables are not bad, but are as good as or better than the WOW XXL.
In summary, in my opinion, the RPM Android App is very useful. The absolute accuracy is a bit off, but the repeatability is very good The wow measurement is also quite good.
76 responses Add your response
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Dear @mijostyn : " The comments about the turntable sounding "dull" only for everyone to decide that the reference system was too bright is a characteristic that is legion in high fidelity systems. There is a tendency for us to prefer brighter reproduction, brighter is better. "I don't think that " brigther is better, as a fact the live MUSIC has that " brihtness " characteristic in a Natural way. So there is brighter and " brighter and not always the same word means the same. That " dull " characteristic you mentioned and the reviewer too came from the listening panel and for those old times the reaction of the member of that panel is just normal because when you listen for the first time a LP with vacuum hold-down audiophiles think that that vacuum mechanism suck the sound and from there the " dull " kind of sound but E.Long posted that after some time listening ( he not the panel members. ) to the Sota he was convinced that the sound is not really dull but more " realistic " and I remember that when I bougth the AT666 vacuum stabilizer as an after market item my first impression was exactly that: " dull " and was disappointed with and time latter on I took in count that the sound was nearer to the reality with the room/system I owned in those " times " and that today in many ways is " different. ".
The sibilance issue is a sound characteristic more on female voice and we even listened in some live events and not necessary associated with poor imaging. In the other side we unknow all the recording process of each LP where the sibilance could be developed but on the playback process some phono cartridges tend to sibilance more than others. As with low bass many times room treatment can't make it disappears. To many challenges to defeat in a home systems where exist no perfcetion but the other way around.
R. |
I think that both of you make good points. For 40 years digital has claimed perfection, while getting better every year. It is still too bright for my ears, but an entire generation has been brought up to think that brighter is better. I have noticed that every major improvement to my system, US cleaning, reflex record clamp, Koetsu, air bearings, every one removed copious amounts of high frequency, yet after a few hours, it was obvious that the sound was closer to the concert hall. So I concluded that what I was after was ’smooth’. Raul talks about there being bright in a bad way and bright in a good way, which I also think is quite right. Mijostyn talks about this too. Might both of you be referring to the leading and trailing edges of the signal? Electronically, this performance is dictated by odd-number harmonics (square wave Fourier Series). Unfortunately, distortion of the odd harmonics is notorious for being offensively bright. I think that you are both onto something.
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Dear @terry9 : MUSIC and MUSIC in a home and its reproduction quality levels belongs to Transient Response. That first MUSIC note and notes attack is what ,for me and my MUSIC life, I think is what defines the step by step MUSIC score we are listen. That transient response obviously develops harmonics. In a room/system where nothing is perfect: where are developed everykind , not only distortions/colorations, of poor transient response according with each system link where something is poor too in some frequency ranges. Your first hand experiences as me and the listening panel in that TT review along the reviewer tell us ( you and me ) exactly the importance of those transient response and what we " losted " through that dull reproduction were only bad distortions right at the " edge " and that now just dissapeared. My last " dull " experience in my system was in the early last year when I decided to change the attenuators/volume in my phonolinepreamp. Years ago I bought those new attenuators that came with the same Swiss mechanism that the ones I used to, difference with the " new " ones is Only that the old ones where builded with true hole resistors and the " new " with SMD resistors. I made the change and was truly dramatic and the first impresion was sad for say the least, yes Dull sound but after a few hours I took again that what I losted were those distortions that normally gives that " over bright " sound. Now those transients are marvelous and obviously puts me nearer to the recording because the brightness is more natural near the live MUSIC brightness. Yes, we are accustom to that wrong brightness. My audio system is full on SS electronics with ( for me ) high resolution . Over brightness lives in many of the audio system links of that system chain. Through the years our ears goes down in its sensitivity and that over brightness is " welcomed " and normally is not our fault till we have that " dull " experiences and then we learn about and take action in that audio room/system. In the other side for several audiophiles that true overbrightness they take as: clarity, transparency and the like when in true are only added distortions what gives that kind of " clarity " and that can happens at both frequency extremes not only in HF.
R.
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@mijostyn : This was what I posted a few months ago in other thread and was not the first time on that issue:
and this related in other " diferent " thread:
Today on those issues is my overall " take ".
R. |
I think your preaching to the choir. Perhaps a better way of putting it would be transient power. It is not just enough to be fast but a system must be powerfully fast. This is one of the characteristics of sound quality. Imaging exists as its own category with a different set of determinants. A system can have the right balance of frequency ( amplitude response) and be powerfully fast but still not image well. A system can image beautifully yet lack realistic transient power and not have the right balancer of frequencies. A great system will line up all these factors, have lifelike transient power, the right balance of frequencies and image correctly. Any variation from the ideal are what Raul characterises as distortions (of reality) |
Is there any scientific data that indicates how a person with "normal" listening abilities perceives audio distortions? What are the lower limits or perception? Is there an emotional reaction to different frequencies? The commonly accepted sating that "even order sounds "good" and odd order sounds bad" is ubiquitous. Is there scientific data to back that saying up? If there are studies of this perception, I would really like to read references to that data. I have difficulty accepting commonly asserted "facts" unless there is data that has been peer reviewed. Pleas note that I am not bashing anyone. I am looking for explanations that are based on studies not commonly accepted sayings. |
@mijostyn : I don't know where you want to arrive. The power is just intrinsical in a live MUSIC event ( no one is preaching there and certainly not the Orchestra Director. ) and I thiink that any one but you already understood what I posted and the links I posted. For your " 20 + " latest posts in the thread you are living inside that imagin that according with what you already posted in the threads is a main characteristic for any room/system I don't know know if you attend to live events to enjoy the imagin. Not me. Anyway please tell me what can you appreciate in a single horn player at live SPL if you are seated nearfield say 2m.?. Maybe you know something that I just missed or we are talking of different " things ".
R. |
Dear @kevemaher : Obviously that you are not bashing anyone but instead of all those questions where you already have the answers then why not really enhance or apport something where all of us could be beneficiated for example: that you take your knowledge levels and make a mathematic model with measurements with the explanations of : what to measure, where to measure, how to measure and what all those makes sense to you and to any one of us. Scientifics along neurologists already made some research with measures how the brain and which brain parts react to some sounds and not specific on sounds of the ones in our audio hobby. In the mid-time you can google for those studies that even in Agon ( somewhere ) were posted and again with no relationship with the audio hobby.
You can start with your self at the end you are an audio hobbyst. R.
R.
R. |
@rauliruegas I would like to understand what type of studies have been made before I make the effort to design and perform the tests needed. Since my last post I have been searching. I have found one (links below) that seems to be quite thorough and rigorous.
https://archimago.blogspot.com/2020/01/internet-blind-test-is-high-harmonic.html http://archimago.blogspot.com/2020/06/blind-test-results-part-ii-is-high.html http://archimago.blogspot.com/2020/05/blind-test-results-part-i-is-high.html
It may not answer all questions on this subject, but does provide some thought provoking results. |
Trying to do anything over the internet is folly at best. There are way to many uncontrolled variables. Most of what people say they hear is imagined which is why rigidly controlled studies with a cooperative panel are necessary to say anything. All audio is personal. We all expect something out of our systems. I want to feel as if I am at a live venue. Needless to say I have never gotten exactly what I expect, close maybe, but not good enough which is why I am still at it. I am a lot closer than I was 25 years ago. This has nothing to do with the enjoyment of music. Most of my listening is done on an inferior workshop system. This is only about the potential performance achievable with todays tech at a less than ridiculous price, We seem to be like ships passing in the night. Are you saying that you can only achieve a satisfactory level of performance at a live performance and that this is not achievable with a residential system? I attend a live performance about every other month. The last was Nickle Creek at the State Theater in Portland Maine about one month ago and it was killer. Chris Thile is a major talent. Their recordings are also stellar. Putting them in the media room is easy. Black Midi, not so much. All I care about is feeling like I am at a live venue. Many recordings make this impossible but that does not mean that I can not appreciate the voices of Billy Holiday or Enrico Caruso. With many recordings it is. System (includes the room) errors like sibilance and exaggerated high frequencies destroy any possibility. Amplitude errors are far more pervasive then either IM or Harmonic distortion. What seems to bother me most with turntables is problems that interfere with pitch, more wow than flutter, things like offset spindle holes and warped records. |
@rauliruegas , Only in instances of unamplified acoustic instruments are you going to perceive a real image at a concert. Many larger concerts have no image at all, they are mono. This does not mean that a stereo system can not create the illusion of real instruments before you. |
@mijostyn I agree.Electronically shaped and amplified music at concerts is highly processed. It can sound really good or horrible depending on how it is set up. A home system should be able to beat an electronically amplified live concert easily. Acoustic music, such as that created by a symphony orchestra, piano or organ in a large hall presents music in its natural form. It is difficult to reproduce this sound at home. Resonance induced colorations in a room at home are in the audio band. The resonances in a concert hall because of its size are mostly below audibility, but echo can be heard The concert hall is designed to damp reverberations. There may be poor sounding concert halls, but these are usually quickly corrected. Music from home systems is highly processed also. We are at the mercy of recording and mastering techs. However, there are a small number of recordings that come very close to the concert hall sound. Solo piano and piano concerto recordings such as "Liszt - Piano Concertos No 1 and 2 Davis Decca VIV 11 (PHASE FOUR )" are my standards. I've found Arthur Salvatore's website, "High-End Audio" to be very helpful for choosing natural sounding LPs.
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@mijostyn : Btw, I attend for several years at least one day each week to listen live MUSIC. """ Are you saying that you can only achieve a satisfactory level of performance at a live performance and that this is not achievable with a residential system? """
Obviously is not achievable in any room/system. Period.
Like you I like too the home system " illusion " ( fake ) that is central part of the home stereo reproduction but I'm not so anal about like you. I wonder why you have not Dolby Atmos?
R. |
Dolby Atmos? Come on Raul, that stuff is for Mexicans:-) What I am saying Raul is only unamplified acoustic instruments present us with a realistic sound field. Everything else is compromised to one degree or another. A great home system is more capable of presenting a realistic impression than the majority of amplified venues. |
@mijostyn : I can't see any one from México but in reality people like you in USA and Europe:
Music Like Never Before - Dolby Atmos Music - Dolby Dolby Live at Park MGM - Dolby Dolby Atmos - Official Site - Dolby
So you are wrong " again ".
Good that you have what you want. That's all about. Enough for me im this subject.
R. |
Dolby is mass entertainment, not traditional music. I may be a :"wonderful" "immersive" experience, but it is not music. This discussion has veered way off topic. Probably time to cap it off. Thanks to everyone for contributing. I have learned quite a bit about how real audiophiles think about this great hobby. I'm not one yet. I may get there.
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@kevemaher : " Is there any scientific data that indicates how a person with "normal" listening abilities perceives audio distortions? "
It's weird that less that two hour after your questions you found out the " answers ". Nothing wrong with that. Now, that's not what I was talking about or what E.Long in the review posted: due to the vacuum clamping all the members on the listening panel heard the difference in the quality/kind of reproduced sound. Not even Long posted nothing about THD or IMD changes with and with out vacuum but more about good damping or as mijo said underdamped . Anyway, in any listen sound pick up by human been ears we have to take in count that ears is only one tool in the human been to identify sound because you, me and ever one listen through our whole body: ears, bones muscles, nervous skin terminations, hair and the like. Not easy to to it overall.
R. |
@kevemaher : Obviously that mijos and I knew Atmos is entertainment and the posts were only mijos and I entertaiment/humor and that's all.
"" We are at the mercy of recording and mastering techs. "2 I have to add : " and each one whole playback process. I own not 3 but all those PHASE FOUR recordings and some ar just ok but nothing more.
R.
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Dear @kevemaher : " I was shocked by the poorer performance of the WOW. Acoustic Signature does not publish specs for speed stability, wow, flutter and rumble. " "" It is very obvious now why Acoustic Signature does not publish these specifications. It could be very difficult to explain why a 70s "entry level" table beats their Double X for wow, flutter and rumble. ""
" " I was fooled. I bought it. One of my biggest audio gear mistakes. Won't happen again."
You posted about specs and what you measured and even that all " against " results to your AS TT you posted something that speaks fine for the listening quality playback of that TT:
""""" I also have a modern table, an Acoustic Signature WOW XXL. The table works fine, although there is no means to adjust the rotation speed. """"""
and when you posted was only ignorance from your self due that that TT you can fine tune the rotation speed. So seems that that TT is fine TT as you posted. The other issue with was that you don't like its tonearm and you changed but even you don't use your Denon because you don't like the look of the Denon unit ! !
""I am also boggled to read that the reviewer summarized that the Double X performance as "high end". ""
Well for the reviewer that unit is " high end " but the issue could be something that only you can answer: what is high end for you? your main reference on your system TTs units and what hipotethically I can think is that maybe your true entry level MS DD-40 is that high end for you: is it? and if it is nothing wrong with that. Your answer appreciated.
""""" I have difficulty accepting commonly asserted "facts" unless there is data that has been peer reviewed. """""
Well in this and almost other internet audio forums for sure you will have very hard " times " .
My take in audio is that must be an equilibrium between objectivity and subjectivity, both extremes are not something good but the other way around.
R. |
@rauliruegas I appreciate your willingness to continue this discussion. However, I have learned much more than I needed from this conversation. I don't regret any of the comments made on this forum. For me however, the need for exchange of ideas has passed. And I have have acted upon what I've learned. A Technics SL-1200G Silver is on its way to me. I will have it this weekend. This will be another learning experience for me. This purchase is a direct result of your recommendation for "high end" turntables. I thank you for that great tip.
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@kevemaher : I never posted that that Technics was a high-end TT so don't put " words " in my mouth.
The next links are only for our friends in this thread could in what scenario I recomended that Technics that is traveling to your place:
https://forum.audiogon.com/discussions/zyx-house-sound/post?postid=2566659#2566659
https://forum.audiogon.com/discussions/zyx-house-sound/post?postid=2567061#2567061
https://forum.audiogon.com/discussions/zyx-house-sound/post?postid=2567138#2567138
Btw, you are welcome.
R. |
@rauliruegas I apologize. |