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Sony WM-D6C

If it is the piece I am picturing on some earlier models based on pictures it was an actual metal circlip. It certainly fits to a notch on the shaft and its role is very simple. I’d expect it to be possible to botch-up a solution, though chances are its still in the machine somewhere! I had to fish one of them out a couple of times with tweezers after dropping it.

PS I spent a while today playing with channel balance. I have some other cassette decks knocking around, the best of which is an Aiwa AD-F810, which is a fairly decent budget 3 head job and has at some point in the fairly recent past been to df_genius for a service. As such it is the closest I have to a reference. The WM-D6C has been louder on the right channel than left on playback, but the quick Steely Dan recording I made on it sounded ok on the Aiwa, so my guess is the WM azimuth was likely ok (plus I really didn’t want to screw that up as I have no reference point). The Aiwa plays the other stuff back in balance that the WM got wrong, so I suspect the other tapes I was trying were ok. Given that knowledge I just nudged RV101 & RV201 by ear to get a central playback balance. I think I’ve got it pretty much right, it is certainly much better than it was. It’s an easy setting to revisit too, plus I have photographic evidence where the trimmers were (upthread), so I can reverse-out if need be. I may try and do it in a more precise manner by recording a mono noise, tone or sweep signal on the Aiwa (I have a Moog synth!), but it’s probably good enough now.
 
This is a jolly good thread, I just checked the serial number on my D6C, 2468**, the head has 35711 printed on it. I've had it stored with a tiny silica jell bags inside and one in the bag it was kept in for a decade at least and the thing still seems 100%. One thing I did notice was how much grunt the hphone output has-looks like it'll drive anything.
 
Yes, its a really good headphone amp. One of very few things I have that is happy driving the vintage HD-414s pictured in the opening post, they sound great with it!
 
When setting levels you do need a full track reference tape. Don’t fool yourself.

Get at least the ANT combi tape. Or walk away from this hobby.
 
Werner said:
When setting levels you do need a full track reference tape. Don’t fool yourself.

Get at least the ANT combi tape. Or walk away from this hobby.
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Interesting, I didn’t realise test-tapes were full-track, though that makes a lot of sense (aside from azimuth, obviously). I found the ANT Audio site, no prices are quoted which implies they are likely more expensive than I could be bothered paying. If I really cared about cassette recording/replay I’d pay for a professional rebuild, but to be honest I just don’t think it is worth that sort of investment. Its a bit of retro-kitsch fun and a means of playing some old band masters without finding a whole shelf on the equipment table for a proper player. I’m currently well ahead of the game as when I got it the thing wouldn’t fast wind in either direction and the image was slightly over to one side. That is now all fixed, so I’ve added £100 or so to it’s value, plus made it a useful device for myself. I’ve certainly done no harm at all in process. I am exceptionally careful with things like this, the only way anyone would know I’d been in there is it now works, and previously it didn’t! I’m certainly not claiming it’s professionally calibrated, it is just better than it was when I got it!

PS I actually care more about the near-mint ancient Sony 204-SD pictured upthread. I am paying for a proper service and recalibration on that one as it is such a nice example and I also have the matching amp and tuner in similar condition. No idea what I’ll do with it, or where I’ll put it, but I do want it to work!
 
You've made it look easy you sod. :D

Mine was a mylar clip I'm certain, but in all the YouTube videos they seem to be v1 or 2 machines with the old boards and c clips (which are so much easier now I have a workable tweezer technique).

Looking more closely I'd somehow had the smallest-tyred idler ride up above its normal position, sitting on top of the pin it should rest against. Sure I didn't put it in that way but there you go. So I took off the thrust bearing again, looked at the spindle without the bearing on and can clearly see the ridge for the retaining clip to fit on, but the bearing when on obscures it, making me think the bearing is sitting too high up.

I've reseated the idler and taken off the c clip that sat on the black wheel below the bearing and used it to secure the bearing instead (so now one clip where there should be two) but still no dice. I must've put it back together slightly incorrectly as everything else seems fine, but I'm a bit frazzled by looking so have asked on TapeHeads if anyone can help. I'm thinking I'll give it to a local fettler on there if she's not busy as I don't want to temp fate by opening it too many times.
 
Given I’ve no intention of paying £70 or whatever for a professional grade calibration tape I thought I’d double-check my adjustments of the playback levels yesterday as best I can with the tools I have available. I produced a 1kHz mono test-tone in Audacity and recorded it onto a TDK SA in the Aiwa AD-F810 at 0db and without Dolby monitoring off-tape to make sure the right/left channels were exactly balanced according to the meters. On playing the tape on the WM-D6C via headphones gives a subjective impression that everything is exactly centred, i.e. I’m happy with what I achieved yesterday and don’t feel any need to redo anything. Again I’m not claiming this is in anyway a professional calibration, but it is subjectively fine.

PS FWIW when subjectively centring it yesterday I slightly reduced the louder channel and increased the quieter thinking that would, as a whole, move things the least from the original factory settings. Obviously I have no idea which was right/wrong, so this kind of hedged my bets a bit!
 
@Tony L - Off topic: is that the Aiwa I sent you...and then got damaged ‘cos I didn’t cut the damned plug off?
 
JemHayward said:
I had a WM-D6C and Nakamichi 700ZXL at the same time. The 'almost as good as a Nakamichi' possibly didn't emphasise the almost bit, but ignoring the frequency extremes, the Sony was amazingly good. It also could play the tapes recorded on the Nak which I used to record quite 'hot' and without even Dolby B (I had the external Dolby C unit for the Nakamichi, but really didn't get on with it). I did quite a few field recordings with the Sony, and recently a friend with a recording studio digitised some old tapes - some were from the 700 and some from the Sony, using a reasonably high end Yamaha that we sourced for the job, cleaned up and azimuth matched to the Nak tapes and I was quite surprised how good they sound. Sadly my Sony died (well became unreliable) after one to many field 'accidents' and the problem was a cracked PCB, so essentially uneconomic to repair. I donated it for spares to a blind journalist who relied on his rather battered WM-D6C for his work, and over the years it donated various bits to keep him going.
The Sony always sounded it's best on battery. My Sony 'official' PSU actually injected enough noise to come out on the tapes, so I built a LM317 based PSU with lots of smoothing - well worth doing, sounded superb. As the rest of my system was Naim I wrote to Salisbury and explained that I would like my homemade PSU for my Sony to match my HiCap so they send me a CB sleeve (possibly foc, certainly not expensive) to put it in. Those were the days!
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Instead of batteries, I ordered a power supply from Exposure for my WM-D6C (I was never good with electronics).
 
Werner said:
And then there were a few decks, including all Nakamichi 3-headers, with full access to tilt, height, and azimuth.

Nakamichi_CR-7A_head_mounting_w.jpg
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I shouldn't be twiddling those adjustment knobs/gears willy-nilly on my Nak CD1.5 then? ;)

It still blows my mind how good a basic TDK-D tape can sound on a Nak.
 
I really wish I’d understood just how important a good three-head deck was back in the ‘80s as I did a fair bit of mastering to cassette and it’s obvious they could have been a heck of a lot better. I’ve been astonished watching things like CassetteComeback on YouTube as to the quality he gets from TDK D etc. Actually to the point now I don’t think there is any inherent advantage to ‘Type II’ or ‘IV’ cassettes beyond a couple of db headroom. A TDK D, a top end Nakamichi and no Dolby is all you need.

PS FWIW, and based on two samples (the subject of this thread and my original in the late-80s) the WM-D6C is simply not in this league. It is a great Walkman, a decent portable recorder, but certainly no Nak!
 
Tony L said:
Actually to the point now I don’t think there is any inherent advantage to ‘Type II’ or ‘IV’ cassettes beyond a couple of db headroom. A TDK D, a top end Nakamichi and no Dolby is all you need.
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All I feed my lowish-end 3-head Nak is TDK-D. I often struggle to hear the difference between source and tape, except during 'quiet' passages, when tape hiss without Dolby gives the game away. I'm still undecided between B, C or none at all.
 
James said:
I shouldn't be twiddling those adjustment knobs/gears willy-nilly on my Nak CD1.5 then?
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Not without the right alignment tape$ and measurement gear. But the beauty of Nak's white plastic gears is that you can easily mark their initial positions with a felt tip, so you can always go back to where you started. With most other decks a full head alignment is far more challenging.

However, you could, if you wanted/needed, adjust playback azimuth on the fly for playing that single wayward tape. Just use a non-magnetic screwdriver with the correct dimensions. You really don't want to damage those gears!


Tony L said:
Actually to the point now I don’t think there is any inherent advantage to ‘Type II’ or ‘IV’ cassettes beyond a couple of db headroom.
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Once you are past basics like a sufficiently smooth tape surface and zero dropouts the only differences are dynamic range, defined by the triad of bias noise, (mid-frequency) maximum output level, and (treble) saturation level. These three define the kind of music that can be recorded successfully.

Well ... of course it is a bit more complex than this. Any tape's distortion/saturation behaviour is a complex function of both level and frequency. If one were to map this function in a 3D plot (taking a zillion measurements, not quite feasible back in the day) I am totally confident that each tape variant would show a unique fingerprint.



One thing I did not know in my early days was that type II tapes are not inherently superior to type Is. Yes, they end up with less noise, but 4dB of that advantage comes solely from the difference between the type I 120 us and type II 70 us playback equalisation standards.
Once you put them on a level playing field the magneto-acoustical differences between, say, XLI-S and XLII-S, or AD and SA, simply disappear.
 
Tony L said:
FWIW, and based on two samples (the subject of this thread and my original in the late-80s) the WM-D6C is simply not in this league. It is a great Walkman, a decent portable recorder, but certainly no Nak!
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I agree; it's not quite the giant killer it was made out to be! I was trying to remember why I got rid of mine and I recall, that mine was obviously used even though it was sold as new and the dealer (can't remember who it was) wouldn't change it for a new one, so I got my money back. The two Naks that I have (670ZX and a 600) are as far as I want to go with cassettes.
 
Werner said:
Not without the right alignment tape$ and measurement gear. But the beauty of Nak's white plastic gears is that you can easily mark their initial positions with a felt tip, so you can always go back to where you started. With most other decks a full head alignment is far more challenging.

However, you could, if you wanted/needed, adjust playback azimuth on the fly for playing that single wayward tape. Just use a non-magnetic screwdriver with the correct dimensions. You really don't want to damage those gears!
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I have no intention of stuffing up the tape path. It seems to be working just fine, except for one wee anomaly. When recording, the left channel would be slightly down in level compared to the right when monitoring off tape. So I adjust the balance to the left at about 11 o'clock. This means when monitoring source, the left level is slightly higher, but I ignore that. On playback, the balance levels on - at least on the Nak. I could live with that. Until I play the tapes on another deck (Denon DR-M24HX - another delightful three-header closed loop twin capstan machine), when the playback level on the left channel would be slightly higher.

This seems to suggest that the recording balance is fine, but the playback level is diminished on the left channel. Is this an azimuth issue, or some electrical anomaly that can be adjusted with some trim pots? FWIW, the FR balance is identical on both sides - at least to my ears.
 
James said:
This seems to suggest that the recording balance is fine, but the playback level is diminished on the left channel. Is this an azimuth issue, or some electrical anomaly that can be adjusted with some trim pots?
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It can be electrical: playback level can be off in one or both channels. This can be adjusted internally (VR17L, VR17R), but you will need a proper full track tape of known flux level. Failing that you could use a tape recorded on a different but trusted deck, but this method is immediately a lot less accurate. And then I am not even mentioning that the absolute flux would be largely unknown, messing up Dolby alignment. It's a rabbit hole one can only avoid with the correct tools.

It can also be mechanical, i.e. wrong head height. Requires a very special track alignment tape, with a 1kHz signal recorded between the L and R tracks. And after that you would have to check and possibly align record head height as well. Oh, and then re-do both azimuths ;-)

All of this of course assuming that the tape path and tape flow are pristine and 100% mechanically 100%. If not, anything can happen ...
 
I am not a fan of TDK D when recording but have been buying some higher-end ferric recently, TDK AR and AD-X. The AR is a particularly good tape which takes as much level as most metals. And I have a healthy number of used-once 1988ih AD too which are a good step up from D. Maxell XLI's are at a similar level.
 
Werner said:
It can be electrical: playback level can be off in one or both channels. This can be adjusted internally (VR17L, VR17R), but you will need a proper full track tape of known flux level. Failing that you could use a tape recorded on a different but trusted deck, but this method is immediately a lot less accurate. And then I am not even mentioning that the absolute flux would be largely unknown, messing up Dolby alignment. It's a rabbit hole one can only avoid with the correct tools.

It can also be mechanical, i.e. wrong head height. Requires a very special track alignment tape, with a 1kHz signal recorded between the L and R tracks. And after that you would have to check and possibly align record head height as well. Oh, and then re-do both azimuths ;-)

All of this of course assuming that the tape path and tape flow are pristine and 100% mechanically 100%. If not, anything can happen ...
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That's really helpful, and usefully cautionary. I'll see if I can find a local tech with the right tools. I don't much like rabbit holes.
 
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