Plinth ideas for DENON PD-80 DD turntable

Beautiful photos, and turntables — thanks PBN. One shows the suspension of the dual-platter (6th from final pic). By removing the allen-heads that hold the leaf-springs, the platters can be separated. You will then see the foam pads, a key element in resonance/vibration control, isolating the playing surface (where the groove and stylus operate) from bearing-noise — bearing-noise (rumble) may be minimal, but it's there. The foam will be rotted and of no use, unless they've already been replaced.

Mine were rotted: crumbly powder, with a bit stuck to the metal like thin tar. The two platters were in direct metal-to-metal contact, totally defeating Denon's ingenious anti-resonance/vibration design.  

The gunk was easy to clean off. I then replaced it with new foam (described in an earlier post). The improvement is quite obvious: low level bearing noise was notable by its absence. It becomes silence, the silence between notes is truly silent, and you can hear subtle overtones and harmonics that were previous masked by the noise — a far more complete presentation of the music and all its subtleties, with concomitant benefits to imaging and soundstage.  

The new foam is readily available, the process isn't difficult, nor is re-assembly — though care must be taken to ensure the two parts of the platter are concentric and thus balanced.

Given that it's not hard, and if you're reasonably handy, I suggest it to anyone with a DP80, if your pads haven't been renewed already. The reward vastly exceeds the time/effort, and negligible cost.

PBN's photos also show that it's not hard to relube the bearing. With mine, the lube had turned to thick sludge at the bottom, with little remaining on the shaft. Again the difference was striking: the platter spun freely far longer, and a stethoscope verified far lower noise.

As above, take care to be sure the parts are aligned/centered properly.

Thanks again for those clear and helpful photos, PBN!

@bima you did everything with the platter yourself ? 

Yes. It was first time too, with no manual, but it’s not hard, just common sense. I DID make mistakes reassembling — alignment and centering, as I mention above — but they were easy to correct. Example: I didn’t center the two-part platter correctly. But the fix was simple: equal-thickness paper shims (spacers) at 5 points around the gap — same way as I center a speaker’s voice-coil in the magnet’s gap.

Also, choosing the new foam was a bit of guesswork: no details were available. I had a few on hand to choose from. Width was easy: if it fits the spaces where the pads go, it’s ok. I then chose highish density (it’s not specified on the packaging) with what seemed sufficient thickness, so it would compress when I tightened the Allen bolts, but not compress too much, retaining the "give" it needs to absorb vibration. It seems to do the job.

Two other easy tips... The gap should be checked between the fixed tape read-head and the moving magnetic-strip on the platter (1000 signals per rev — that’s about 2000 per second: very accurate). My gap was WAY off when I got it.

It’s easy to set. I used a precision feeler gauge, but even the Service Manual (which I got later) says just to use a business card. After reading that, I went back and checked the gap I’d set "precisely" with a gauge, this time with a business card — and the card was spot-on.

Checks yours with a card. If it’s too wide or too narrow, there’s only one screw to loosen, you’ll see it — set gap with card — not too tight, just so you can remove the card without a struggle — then retighten screw. Easy.

BUT at all times be SUPER-CAREFUL of that magnetic-strip. I don’t even touch it (skin-oils etc).

One more: when the platter is removed, you’ll see a small electrical switch. It’s marked 50Hz or 60Hz. Set for your local system of course. BUT the switch is a bit misleading: it LOOKS like a slide-switch, and the labeling (50 vs 60) reinforces this false impression. But it’s really a push-switch — DOWN is 50Hz, UP is 60Hz. (I mention it because mine was set wrong when I got it.)

I assume you know it’s a 100V unit (unless yours is special) so a step-down transformer is VITAL, especially in 220-240V territory. It needn’t be a massive step-down: the current draw is minimal (mine has a 1-amp fuse, but it’s for US 117V). My step-down is small, easily hidden out of sight, and it’s worked fine for a decade.

Of course a pro would double-check everything with instruments, which I don’t have, but if the instruments detect a problem, it’s most likely with aging, out-of-spec components on the circuit boards, not the simple switch.

I hope this helps.

Thanks @bima I hope it will help our readers and users of DP-80

My unit was NOS, probably unused, i only did the correction of the spindle position by unscrewing 4 bolts from the bottom and tightening them again after checking the position of the platter by verifying the gap around the platter from the top side. My motor block with the spindle was a bit off-centered (probably in the shipping process), but it was very easy to fix.

The tape read-head is spot on and everything is just fine and rotation is nice and smooth (noise free).

I only think about the lubrication, i have the oil supplied for my ex Technis SP-10 mkII by KAB. I can definitely do that if it’s necessary. But how many drops of oil i have to add ? I remember for SP-10mkII the recommendation was just to use a few drops (maybe 6) ? @bpnaudio I wish to prevent leakage of the spindle oil all over the drive inside :))

Still not sure about the damping material inside the platter, they do not recommend (in the manual) to unscrew the platter. But if you did that yourself maybe i can do that too.

Direct link to the material we can buy for the platter would be nice.

Your all welcome

Clarification - the 50/60 Hz switch only function is to add capacitance to the motor capacitor nothing else.  And all units are 100V so a step-down transformer is required for long term reliability.  

Good Listening

Peter