Excessive Wow & Flutter in Sony WM-2 (0.78% RMS with 8Hz Spike)

Hi Norm,

Thanks for the note! It’s reassuring to know I’m not the only one who couldn't track down official W&F specs. I’ve restored a few 1983 Panasonic boomboxes in the past that sit around 0.2% WRMS (against a 0.3% spec) and sound perfectly fine. Given how superior the Sony WM-2's mechanical build quality is by comparison, this performance hiccup really caught me completely off guard—a unit engineered this well shouldn't be performing like this.

Like you, I always give my audio gear the full "spa treatment"—sparing no effort just for my own peace of mind (and because I genuinely enjoy the process).

Before starting this project, I watched several videos and read through @Valentin's tutorials, so I was well aware of those door mechanism bearings jumping into the abyss! However, this "mystery ball bearing" was much smaller than the two door detent bearings. Naturally, the donor unit’s shaft was clean, so who knows where it came from.

The belt is certainly still a suspect as well. While Marian’s products are consistently top-notch, strange defects or batch variations can always happen. I usually buy belts from Neil at Russell Industries—great quality and prices—but he doesn't have the right size in stock at the moment. Would you mind sharing the US eBay vendor’s name so I can check them out?

I'm currently waiting on the replacement parts to arrive so I can start swapping components and see where that leads. I hope to take a victory lap (or maybe two) at the end of this project.

Best,

Alex

 

Sure, Alex, I bought from https://ebay.io/m/DXPppR Speaking of Marian, I received my order for the head block lifter and a few other parts today. I always get a little anxious when ordering from overseas with no reliable tracking, unless one wants to pay the $50 for DHL. Cheers! Norm

 

I would be happy with 0.3% WRMS on this particular unit. It's not a great figure, but it's ok for most genres and will only be audible with music with very long note decays.
A good figure on this unit would be ~0.2% or a bit lower (0.17-0.18% for example), but anything below that is extremely unlikely to be achievable.

0.1% WRMS is already DD territory, hence why when belt driven mechs obtain such figures it should be treated as the exception, not the rule.
There are some belt driven mechanisms that can obtain such figures but they're few and far between.
Contrary to what some believe, 0.3% is a figure many walkmans (even high-end ones) won't be able to outperform no matter what's done to them.

Regarding W&F specs, most belt driven walkmans don't have such specs and there's a reason for that.
From the ones that do, Pioneer has a <0.28% WRMS on their mech, AIWA gives a <0.45% WRMS even on their high-end devices, Hitachi gives a 0.2% WRMS, etc.
Interestingly enough the belt-driven devices some people take as reference (SONY WM-FX35 - 0.15% on a consistent basis) do not have a spec.

 

Thanks, Valentin, appreciate the insight. Cheers! Norm

 

Thanks, @Valentin—really appreciate the context and insight here.

It's interesting comparing this to my Sony WM-GX670 (which you helped me fix a while back). That unit consistently hits now 0.13% WRMS in both directions. It’s obviously a much newer design with a lot more plastic in the mechanism, but it performs. Still running without that one missing capstan fiber washer, too.

@worldwide137 Norm, thanks for the link! I will order a belt for WM-2 from him as a test.

Overseas orders are tricky and expensive: I try to avoid them if I can help it. Fixyouraudio has proven to be 100% reliable.