Hi there,

As I explained in my previous post, I received a specially modified SONY D6C by doctor Walkman to achieve an extraordinary level of quality. I used it as my reference point and started to do measures, just to learn about the quality that a tape can achieve and the real differences between some walkmans.

I don't want to make extraordinarily exact measures, as I know it maybe requires special (and probably expensive) equipment, but enough good measures to fill my interest to learn about this.

As digital sound is well known for being less imperfect than analog sound, it's a good idea to use it to measure. The key is to use the aproppiate equipment, and computers are the best equipment. So I tried to do it. I used for many years a good sound card that serves me so good: the Creative Audigy, the first model with external rack. But I wanted to upgrade to a modern, better model, so I bought the best card that this brand ever released: the X-Fi Elite Pro:

This sound card achieves more than 120 db of dynamic range (the best tape system can be closer to 80 db) so it's way ahead the tape system, and appropiate to measure it. It really sounds awesome, but I like also the warmth of analog sound, and that's why I want to digg in it.

For doing the measures I connected both Line-IN and Line-OUT of the D6C to the Line-OUT and line-IN of the sound card, respectively. I bought high quality cables also, to keep the signal as good as I can. Then I tried to use TrueRTA analysis software, but I found it not so well suited as RightMark audio analyzer (RMAA), and I decided to use the last one. It's easy to use, quick, it does a complete set of analysis and it's free:

The first thing I tried to learn is how to adjust the record level on the tape while recording. I know that it has to be as high as it could, but avoiding distortion; this way I can achieve the best dynamic range (DR) and the lowest background noise.

Doctor walkman has calibrated my D6C for my usual chrome tape: Maxell XLII-S, but he also suggested that the TDK SA and UX-Pro are similar and better, and that he can calibrate for all them (then I started to search for them on eBay). So I picked up a Maxell XLII-S clean tape, as I already recorded some tapes and I knew how good/bad does it sounds (more or less) and wanted to know how does it performs actually.

I first recorded the full RMAA test until the initial calibration signal (1000Hz at -1dB) reaches 0dB in the D6C's VU Meter. Then I repeated it to +3 dB and +6dB. I analyzed it and I saw strong non-linearities in the frequency response curve, so I decided to try 0dB but a bit lower (so the LEd just blinks a bit and not so it's fully ON)... and the magic came. This is the main result window in RMAA with 0dB, +3dB, +6dB and 0- dB (this last one means 0dB just blinking):

And here it is the freq. resp. curve for all them, where you see that only the last one achieves a pretty good response curve:

so, that's it! I have to keep the level until it doesn't fully ON the 0dB LED.

As you see in the main result window, I can achieve 59dB of DR with this tape, whithout using dolby at all.

So after that I picked up a TDK SA90 (which Dt. Walkman told me it's not so good tape) and a TDK SA60 (which he told me it's the good one) and I tested them. After searching for the appropiate recording level, I found that the SA90 is not so good tape indeed, because at 0dB it's heavily distorted, and I only achieved good results recording at -10dB:

Main results for TDK SA90 recording at 0, -5 and -10dB

Look at the frequency response curves (FRC from now on) and you will see the difference:

Freq.resp. on TDK SA90

So I compared the Maxell, the TDK SA90 and the TDK SA60:

Results for Maxell XLII-S, TDK SA90 and TDK SA60

And here are the FRC:

You can see here that the best results are achieved with the MAxell and the SA60, obtaining about 60dB of DR each. In fact, a later test with the TDK SA60 showed slighty better results.

Finally I wanted to see the difference between a top-level player, a very good player and a budget player. So I compared this superb D6C, the AIWA PX505 (in fact, my silver japanese PX50 version) and my loved SONY B39 which was with me when I was a teen:

Comparing the AIWA PX50, SONY B39 and the 'super D6C'

As you can see, the D6C is better in terms of intermodulation + noise, thanks to it's transport stability, but the budget B39 player is surprisingly better in DR. Let's see the curves:

And here you can see how the SuperD6C outperforms the rest, whith the B39 having the worst FRC, the PX50 having a pretty good one and the super D6C having an excellent one. the explanation for the high DR level of the B39 is because this software recordsthe best peak level achieved but doesn't show a weighted measure. Here the curve shows all the info.

(to continue)

I have no idea what all this means - but it looks lovely

apparently you can also prove a Jaffa cake is a biscuit in lab condition

the proof in the pudding is how it all sounds on the best device known to man

your ears

As nice as all the pretty graphs are, there are limitations to using software such as RMAA especially since the software makes some very big assumptions when computing the data. I discovered this when I had a play myself with the software.

For a more detailed reasoning as to why trying to use RMAA to compare and contrast audio hardware is not a good idea see here ---> http://nwavguy.blogspot.co.uk/...o-analyzer-rmaa.html

Hi Claret,

Oh, I know all this can look so technical and a bit understandable. Let me explain it a bit. Sound is a signal that has many measurable characteristhics. some are pretty obvious (volume, tone...), other are not so easy to measure (background noise,...) and there have been a lot of discussion about if other are measurable or not (warmth of a song or a music device).

For measuring how good or bad is a audio device (a music player in our case) we can measure some basic things. We can do subjectively or objectively. I believe that no one is better than the other; however, a subjective measure is more valid when it comes from someone that is very experienced (that's not my case actually) and respected.

So, as I'm very curious and like to digg to know the basic nature of the things I really like (like music and photography), I thought I could do some objective measures.

This way I could see clearly why many people say that the SONY DC2, DD9 or D6C are so good players and compare them, for example, with the SONY 701C or the AIWA PX303 or PX505.

As any technical study (and mine tend to be) I started by assuming no truth. The SONY D6C is not a good player only because everyone says it. I have to check it.

So I chosed and bought (specially for that) an excellent digital sound card and the first thing I did is test it. A simple loopback test (play though the LINE OUT and analyzing on the LINE IN) will tell me any imperfection in the measurign tool. That's because any problem while playing WILL BE ADDED to any problem while recording.

One of the most common audio tests is the frecuency sweep (I attached a sample audio file so you can heard how it sounds). That's a tone that starts in the extremely low frecuencies and bit by bit is becoming higher frecuency until it reachs the highest frecuency audible. That's from about 20Hz (ultra-deep bass) to 20.000Hz (ultra high beep). Playing this sweep tone on a device and analizyng what is heard, you can get an idea of how it manages the whole spectrum. For that I use that software, that plays and analyze the incoming sound. Also, it gives you a .WAV file (with no compression) with this sound, so you can play it in any digital device (you can record it on a music CD) or record it on an analog device, like a tape. so I recorded it in a tape with my D6C, trying to get the maximun recording quality.

When analyzing it, normally it's displayed on a graph with the whole spectrum in the H axis (from deep bass at left to high tones at right) and the "volume" (expressed in dB, 'decibels') in the V axis.

I analyzed my sound card with that mentiones loopback test and the results were simply excellent (as I suspected):

As you can see here, an almost completely straight line goes from left (20 Hz = ultra deep bass) to 20KHz (= 20000 Hz = ultra high beep). The biggest variation in the V axis is about 0.5dB, which is barely noticeable. To your reference, when you switch the "megabass" ON in a modern walkman, the bass is pushed up about 10-16 dB, so 0.5dB is really very light modification.

This tells us that this sound card has a really plain response on the whole spectrum. More on, this is the "errors" while playing PLUS recording. So the "errors" in only one of them should be about half of what we actually see now (about 0.25 db).

an integrated sound card (those that normally come in the computer are much worse than this one, except in high quality computer, like workstations (like DELL Precision) and probably in MACs too. I tested the integrated soundcard in my worstation notebook and I can tell it has surprinsingly high quality (much higher that I expected). However, it lacks any EQ or basic enhancement.

So if you look at the curves that I posted you maybe now understand much better how does it perfomrs the SONY D6C with various tapes and versus other walkmans.

another interesting measure is the background noise level. This measure (expressed in dB) tells us how much noise is there compared to the highest sound achievable WITHOUT distortion. This means that to measure the noise, first we have to adjust all parameters so we can do a record of a sound at the highest level possible on that tape, without distorting it. Then, we simply play a segment of the tape where we don't have anything recorded, so we can measure the noise. The lower the noise, the better the device. Measuring the volume difference (in dB) between the recorded sound and the noise we can get a precise idea of how good that walkman+tape performs. This noise measure is almost the same that the dynamic range.

there are also other measures, like THD (Total Harmonic Distortion, Intermodulation distortion, stereo crosstalk) but some are more difficult to understand. The most interesting ones are the two I commented and the wow&flutter (but actually I didn't measured them).

Hope I helped you and others to understand all that. 

Thanks Plop, your advices are always welcomed, really.

I'm reading the artilcle you point to (and another one) and the more I read, the more confident I am that I did things pretty good in my case.

Although I was aware from the very beginning that I cannot take 'absolute' measures with my equipment, to measure FR curve and noise level with my equipment and with my setup, I think I did things in the proper way. Also, I don't want to measure so advanced measures or to measure things I couldn't with my sound card (like output power), so for now I'm pretty hapy with RMAA. The only thing I would like to measure is wow&flutter. I know someone told me about a russian software to measure it a while ago in this tech talk forum, but I still didn't test it.

When I complete reading the article I'll reply you with a more detailed explanation, ok?

Hey Hugo,

It's ok. I was trying to set up RMAA, and stumbled on the link above when doing so since the instructions for RMAA were so vague.

After reading the link, I've decided against using RMAA since even if I were to create any graphs they would be meaningless outside of my own personal testing setup and not readily comparable to anyone else also using RMAA.

I have to admit I did not attempt to measure my DD9 before or after I sent it to dottor walkman. I did not measure it as you need very accurate equipments, which usually are very expensive plus you really need to set it up under strict lab conditions to get any meaningful results.

I just use my ears, since that is the ultimate test. If you get good measurement and the stuff sounds bad to your ears, it’s still no good.

When I sent my DD9 to dottor walkman, I told him a few things I noticed while listening to it. When he put it though the oscilloscope he found what I had mentioned, confirming what my ears where saying.

About the only thing I do measure and setup properly is my record player, but then I had invested in high-end kit to help me set it up. A high-end turntable setup badly is worse than a cheaper one setup properly.

If you have a turntable that you want to get the best out of, I recommend these pieces of equipments.

Cartridge Man’s Digital Stylus Gauge http://www.thecartridgeman.com...ylus_force_guage.htm

Dr. Feicket’s Alignment Protractor and Adjust+ software http://www.adjustplus.de/index.php?lang=english

Indeed, sometimes we forget the obvious - our hearing. Afterall, the quality of the audio is all subjective to the ear of the beholder. Why else is there such a wide range of different audio gear out there to cater for everyone's differing musical listening tastes?

The analytical machine could draw a nice graph, but that may not translate into a nice sound. Only the owner of said pair of ears can decide if the sound is good to them or not. Having the graph just pictorially shows what is considered in the opinion of the listener to be audibly acceptable to them. 

Hi,

After reading the NwAvGuy article, which is very interesting and I agree with him in almost everypoint, I have to say that I think that you don't get my point. I'm not trying to make absolute measures that can be compared with this guy's equipment. I already knew that my measures are faulty. But the point is 'how much faulty' and how useful are them. What if you know almost anything minimally precise about the audio quality of a walkman?

For example, what people usually know about the audio quality of a well-known walkman (let's say: an AIWA G08, i.e.) is... nothing. absolutely nothing. At best, the have their own opinion or had heard other's opinion, which is pure text: "sound good", "excellent", "decent performance", etc...

Some goes far and know that it can go "from 40 to 14kHz with a chrome tape". But, what kind of precise info gives you someting like "sounds good" or "40-14kHz"? Almost none. The only truth is that it can play 40Hz and 14kHz, and everything between, but the manufacturer didn't say how.

So, what I'm trying to discover is a bit more than that. I don't want a bunch of hardly understandable graphs to a reader, like THD+noise or a complex analysis. I just want to know a bit more than that highly subjective and imprecise "sounds good" or "40-14kHz".

I started doing tests with my old sound card, and Creative Audigy (1st generation), which was a pretty good card. I disabled any sound enhancement (EQ, cristalizer, surround, etc.), disabled any OS sound, closed any software that can play intrusive sounds (like email or skype) and adjusted the mixer exactly as Creative engineers recommend (in a PDF document they released). I got this freq. response curve (FRC):

so I knew something goes wrong. However, is not so wrong: the biggest variation is less than 0.5 dB. Knowing that many walkmans have probably desviations of more than 3-5 dB it's not so bad. but I decided to change the sound card and bought the best one I can get, and compared both (green is the new one):

and the new one is clearly better, almost absolutely plain from 20 to 20.000Hz.

NwAvGuy says: "RMAA results are only as good as your soundcard and how RMAA is used. Lots of people are running RMAA on whatever sound hardware their computer came with. And that's often a serious limitation."

I completely agree. And with this sound card I can say I'm prepared to achieve pretty good results (less precise as his results, obviously). This sound card costs about 400 euros, so it's not exactly like a built-in hardware. Yes, it's far from the $5000 oscilloscope but it's a big step ahead from the build-in card.

NwAvGuy says: "Unless you know the absolute levels used, load applied, PC sound hardware used, and settings of the PC and device being tested, you simply can’t trust the results. Changing any of these things can cause a greater change in the results than testing a different audio device."

I completely agree. So I did stablish a set-up for my measures: always the same sound card and cables, always the same input, all sound processing disabled, input level at maximum (to use all the bit depth of the sound card), all other inputs muted, no cable unplugged (to not get residual noise), no other apps running or CPU with load, etc...

So, if I compare the performance of the sound card and a budget walkman, like the SONY B39 (which can play from 40-15000Hz and "sounds good", at least for me, for many years), I can see that their FRC is like this:

On which the X-Fi card is perfectly plane and the B39 is more like a mountain road. This performance of the B39 was measured with a high quality tape recorded with my 'super D6C' having achieved excellent results when played on the same D6C. So the problem it's not the tape, it's the player.

seeing this, are you telling me that this graph is almost useless? I know that if I put a loupe over the graph, I'm sure that many small measuring errors exists, but the main curve goes like this.

Let's see the noise level (which I say that this graph is badly captured, I already know):

Here you can see the huge difference between both devices. When the B39 only achieves

a minimum of about -60dB (where a problem of low power output that at maximum output was about 20dB under the proper level, making this measures to be 20dB lower than it should be), the sound card achieves less than -120dB. So, being the sound card about 50dB "quieter" that the walkman (which is a HUGE difference), can't I measure the noise level, which is a pretty noise device with another device that is FAR better than it?

I think so.

In other words: am I'm doing wrong to measure "a few inches" with a "milimeter rule", only because there exists "1/10 milimeter rules"? I don't think so.

I know my measures are yet to improve some problems and errors, but I'm pretty sure that they are very useful to let me know how (briefly) any walkman performs.

Of course, if it come accompanied with a good, subjetive description about how good or bad sounds (by some experienced and respected audiophile), it's even better, but providing only one of them is worse. Just graphs or just subjetive description is -for me- an incomplete, faulty review.

I'm surprised that I wrote brief, very subjetive descriptions in the articles of my website and no one told me ever anything about them. I just said things like "sounds very good", "has good bass" or something else. Now I'm showing far more precise data that those simple words and some are questioning them. Well... I don't know what to say. I'm very surprised.

Regards,

Last note: (just to clarify) the TDK SA I chose is the newest version.