Hi there,

I want to share a very interesting experience I've had with 'dottore walkman', the walkman technician. I knew about him in this forum more than a year ago and I contacted him for doing some adjust on me best units: SONY D6C and DD9.

I wanted to send him my D6C for doing a complete test, manteinance and calibration for my tapes (Maxell XLII-S, TDK SA and UX-Pro), so I wanted to do good quality recordings. I know I can buy a top-quality tape deck like a Nakamichi but I prefer to have a small unit like a D6C. He told me he can do this to achieve a very fine and high quality sound.

My SONY D6C, one year ago.

But a bit later he told me he can do a much better job: he can perform a special upgrade and build a 'super D6C' by selecting parts that he can pick up from other D6C units, do change some components for better ones and calibrate for my tapes. He explained that I have to buy another unit with a serial number carefully selected, and I did. In fact, I bought two units more, so I finally sent him my three D6C.

One of them (the first one I bought, in fact) sounded pretty good for me, much better than any other unit I have in my collection. In fact, I was really impressed by its quality, much better than any other I ever listened to (I have to confess that I never had a top-quality tape deck at home, except my ONKYO hifi system which has Dolby B-C-HS Pro, but lacks manual record level or bias.

The other two D6C had small problems, like noise or distortion.

So what he did was:

- to dissasemble all three units

- to select the best parts of all them unit until the traction of the tape has reached a perfect stability and a greater tensile force than the specific (Sony 25-43 g/cm), an excellent wow and flutter, etc..

- to select the best electronic components both for mechanical performance (speed, wow and flutter), for both recording and playback, specifically for my tapes (Output Levels, Bias, dolby output)

with all that he built a top-level unit, indeed, but he needed to take a lot of time for that. This artisan of the walkmans has really done and impressive work. I can not recommend enough him for repairing walkmans. He is a truly precise artisan of the walkmans!

Finally, after a very long wait, I received a few days ago my 'Super D6C' and started to record and do listening tests. Be in mind that I didn't listened to an excellent recording or a top-level tape deck before, so I don't know which level of quality and fidelity can be achieved with tape. But I have some excellent headphones (Sennheiser HD280 Pro reference studio, Grado SR325i, SONY CD3000) and normally listen to (high quality digital) music in my computer, using an excellent sound card, the Creative X-Fi Elite Pro, which features an 'advanced multi-bit Delta-sigma DAC' and has about 120dB of dynamic range and -110dB total distortion+noise, so it's a very high quality circuitry. Thanks to it I have to say that I know how does it sound a high quality music, but I don't know how a good tape compares to it.

The first thing I noticed was that the speed stability (wow&flutter) is absolutely excellent, and there are inexistent small duration problems while playing tapes. I mean: normally when I played tapes on good walkmans, I always found that randomly appear small (very short duration) problems that seems like it there were a small dust on the tape or on the head when recording (I know that this is probably not true, but it's my way to explain it). Probably has more related to non uniform tape transport or small irregularities on the capstan and roller.

With the super D6C they are simply inexistent. but they were present in it before I sent the unit to Doctor Walkman.

 
My latest jewel: the 'super D6C' by Doctor Walkman.
I asked him to send me his signature on a paper and I managed to scan it and stamp in the image, with his permission ;-)

The second thing I noticed is the excellent response to the whole spectrum. For doing that, I recorded (without dolby at all) in a clean Maxell XLII-S 'Come rain or come shine' from 'riding with the king' album, by Eric Clapton and BB King, which has a powerful bass, good voice and precise guitars. I was simply blowed out when I listened to it. the most impressive thing was the clear and powerful bass and the open sound (remember that the D6C hasn't any eq adjust or preset). It's clearly way ahead the response that it had before I sent him. I'm pretty sure that sounds clearly ahead than an iPod, in terms of equalization. The sound is open, very well balanced, stable and clean.

Another thing I noticed and surprised me a lot is that if you play with dolby C a record that wasn't recorded with it, the sound is horrible: strongly cut highs and very poor performance.

But (here comes the magic) if I record WITH dolby C ON and then play with it ON, the result is simply AWESOME! The sound clarity is almost identical (or even better) than playing without dolby and the highs aren't cut at all. More on, the backgound noise is really low (I measured 14db of difference).

Then I played this record made with Dolby C on other units of my collection, and I realized that on the AIWA PX410 (which has Dolby C too and is known for being a high quallity C circuitry) the result was awesome too. I switched ON the DSL to position 1 and I was blowed out!

But I was really surprised to discover that playing this tape on my AIWA PX505 (which it's dolby C is 'standard' and normally cut the highs) does NOT cut the highs as I normally expected. So this superb D6C really has a Dolby C circuitry that outperforms all that I ever tested and allows to play a record on small players equipped with dolby C, even those that normally cuts the highs a lot.

With the help of Doctor Walkman and my computer equipment I could start to do some measurements and learn a lot about the real quality difference between recording and playing on many walkmans. This also can show me which quality can be achieved with a good tape and deck, so I can have a good reference point to compare with many units. I'll post my first measurements on another post.

He good, I thought I only took the time. I saw what he did to his DD9, he definitely good, he took the best parts out of the different revisions, as each had their flaws.

That sounds fantastic. Did one of the modifications involve inserting a real Laser Amorphous head from an early unit to a newer one with the SMD board?

Was wonder the same thing, also if he change the capacitance for better frequency response on the lower end and to work better with higher impedance headphones. Still wonder why he needed three, that had to be expensive. Wonder if it was really worth it in the end? Just get a Pioneer Elite CT93 to record with, or most dual capston three head quailty home decks with good decoder section.

His work great, but to me seem like a waste of two other D6c, unless they were unrepairable, or not worth the cost. I can see the point of the upgrade if you can still buy the parts like the head assy and ETC, then makes sense.

Don't tell me it took a whole year?

You right about the super D6C they are simply inexistent!! Now to work on the super super D6C with dual capston and direct drive servo motors, with quartz lock, so wow & flutter, is not even measurable, auto azimuth alignment head, for better head height accuracy and alignment goes by tape being played and test tone. Screw Dolby C, now improved with Dolby S for extended high frequency respones, provides even more effect than ever before (up to 24 dB) and manual BIAS controls, so you don't have to deal with the factory preset, with record sensitivity calibration, not to be confuse with record level. The only problem is, don't think it would qualify as a D6C anymore, let alone a walkman? 

Regarding the change of capacitors, I know he didn't do that because he doesn't like it (as he told me when I told him about a change purposed by Plop here), but I don't know if he changed the head. It's best if he reply; I'll ask to do it.

To be honest, don't like it etheir, like the flat response better, with more detail. Wonder the upgrades in more detail he did, beside adjust the Output Levels, Bias, dolby output, which I already do. But mostly interested in the transport upgrades.

The mod indicated in the link posted previously does not add to or pump up the bass. It only changes the delivery of the audio such that to enable non-professional grade headphones to avail of the bass that is hidden from them.

So in conclusion you would still have the flat response, but with extended lower response before roll off when using non-professional headphones. It is a professional rated cassette deck after all.

Hello everyone,
first, I apologize for my bad English, but I use the google translator.
Hugo knows as well, my work took a long time because:
1 - I had and I'm still having some health problems, which have greatly reduced my available time to work on Walkmans.
2 - I need some time because I have many Walkmans to repair and we are confident that many people, fortunately, have the patience to wait, I thank them all. Besides, I'm all alone to carry out these works in my lab, no helper. Also, I do not consider my job terminated, until they are 100% happy. Although, very often, time spent, far exceeds the agreed amount.
3 - I think that the operation carried out by me for Hugo is very convenient (otherwise I would not recommended) because:
   A) First, I think the Sony WM-D6C, it's potentially equal to a the best decks Nakamichi, so in that exclude many decks, including Pioneer, etc.. Obviously this is my thought, but supported by years of experiments and comparisons in the laboratory. However, it is just my idea and I do not want to impose it on anyone. I just say that my personal D6C, which I've done many UP-GRADE, keeps track equal and even better as the best decks Nakamichi, of course, to my ears and my tastes. I say this because I made many tests and comparisons.
   B) The three D6C of Hugo, had flaws can only be resolved with excessive spending, without which it would be reached, the quality desired by Hugo. Instead, this way I got for Hugo, a D6C excellent, a standard D6C, and a D6C not working, only for parts. In the coming days I will work to finish my work on the second D6C of Hugo with standards quality, in this way, Hugo has an excellent D6C, A D6C with quality standards and a D6C as a source of spare parts. This is what I would do for myself and, therefore, is what I did for Hugo.
   C) Hugo asked me that would the D6C could keeps track perfectly high quality chrome tapes, of course, the low sensitivity can not be included, since the D6C non have the variable bias.
Hugo is not very interested in the metal tapes, so his D6C keeps track perfectly the chrome tapes and normal tapes, but not the metal tapes, unless he uses a TDK MA-XG new version.
   D) I have proposed to Hugo all the changes I made on my personal D6C, for got a wow and flutter equal to the best Nakamichi decks, and for keeps track high-quality metal tapes. The same change for Tuna (also a member of his stereo2go). Unfortunately to do this I need others components I'm looking all over the world and the list is not complete. So that Hugo had already waited a long time, Hugo decided for this solution. If Hugo wants, in the future we will continue improving its D6C, when I have all the necessary components.
4 - As regards the head of the D6C and mother boards:
I do not agree with the latest versions of D6C mother boards in vetronite is better. I'm not talking of the permalloy head which is also worsening. I mean really talk about the mother boards. It is built with a type of vetronite but not it's That used on the mother boards of DD9, that in the D6C is very poor. The choice was made for economic Reasons And Also to use SMD components of a quality not satisfactory for me. The old bakelite board, is better.
5 - However the important thing is the tolerance and the combination of the various components which results in an excellent or mediocre result.
In fact, most of the D6C that have been produced, does not keeps track in an excellent manner, but only discrete. Then there is a small amount of D6C who have a combination lucky. Also, very few indeed, who have the mother board of the latest generation. This shows that guess the correct combination is as important as the quality of components. If the two come together you get the maximum. (So I always prefer to make the up-grade on a D6C older generation.) This minority D6C already keeps track with a good quality. With few modifications, they can reach a state of excellence. Instead to achieve the status of excellence of the remaining D6C, which are the majority, it takes more invasive and costly changes. Hugo chose a good compromise, giving up to the metal tapes.
6 - As for the head that I selected from 3 D6C:
it has been chosen according to the tolerances with the rest of the circuit. Hugo can take a picture of the head.
7 - Hugo If you wish and if you think it's worth it, when I have all the necessary components, I will make a further improvement of the wow and flutter, until you achieve the wow&flutter of the best Nakamichi decks, as I did for my personal D6C.
8 - Finally, in the past I made on my personal D6C, the change of the expansion rate: from 40/15000 hz to 20/20000 hz. The result was welcomed to the oscilloscope, but not with the ears, nor mine nor of others. Also, when you listened to the monitor, the source (ie, while recording), the oscilloscope showed the shortcomings of the sine waves that were to be eliminated from the MPX filter removed. Even if the recording was perfect, I decided to restore my D6C with the original frequency response (40/15000), because this is a change that is not worth it. For this reason I have also recommended to Hugo.

Hello Plop, I found yours advices very interesting and useful technical, including also the change you suggested for the D6C, the fact that I have not used he has not taken away absolutely no value to it. Indeed, I believe that all of your tips are very useful to members of stereo2go, even those that are the result of your personal opinion.

I apologize if my message is too long and tedious. I hope at least is clear enough, as I already said I do not know English well.

Hello dottor walkman!

This was and is a very interesting story.

I wish that i could fix all my electronic machines by my self,but i can not enough of technics to do this.

I have a question if my wm d6c is the old one?

serialnr:13775

I second what DottorWalkman said but am not pretending to know everything about his work. His level of workmanship and in the case of DD9, hand craftsmanship, is like nothing I've seen. Everything is backed up by measurement.

I would like to point out some of the problems concerning the availability of quality components. The bypass polyester capacitors are a big problem. Their quality in this case is a critical issue and there are only so values that can be had in a true high-end format (either Wima MKP vintage series or the Vishay/BC mil-spec series). Though we have the most of what we need, the rest has become a problem.

To Marrea: your D6C is part of the first series, one of the best. You are very lucky. With the appropriate upgrades, your D6C can become great.
To Tuna: thanks for the further explanation, as usual you can explain much better than me.

Hello dottor walkman

By chance do you have plastic battery compartment for the first revision with serial 11460 and leather case?

Thanks for your long explanation, Dottor walkman. I will simply add a bit:

1) I decided to not explain that by myself, as it's a personal information that I think only you can tell public.

6) I'll take and post it.

7) As you already know, yes, I'm interested. But first you have to find those super-rare components. However, if you ever find them, I'm pretty happy with the actual performance :-)

Hello retrodos, tuna, plop, marrea, bub and hurodal,
first of all, I wish a Happy Easter to you and all stereo2go members.
To retrodos: sorry, I haven't got the parts you're looking for. Should I happen to find them in future, I'll let you know.
To hurodal: thank you for your kind words.
With regard to further improvements for your D6C:
WOW & FLUTTER: This upgrade is a further improvement that you can evaluate only your instrument, not with your ears. So, it might be interesting, when the time comes, you run the tests, on the your wow & flutter meter before I perform the upgrades. In this way you can see the difference at the end of the change.
METAL TAPES: This upgrades is quite complex, given the nature of your specific D6C, then I recommend if you really want and if you can find enough metal tapes. If you manage to accumulate enough metal tapes, preferably of high quality, everything will be easier and cheaper.

Wow&flutter: Sounds interesting, but I haven't found yet the way to measure it. We'll talk, ok?

Metal tapes: I think I'm not interested. MEtal tapes are so rare and chrome tapes are still available. With the proper calibration, as you teached me, very good results can be achieved, so I prefer to keep with chrome.

Can you please tell me how to get in touch with Doctor Walkman?

I have a D6-C in need of doctoring.

Thanks so much.

Send him a private message through this forum.