I own a Dp80. It is perhaps too simple to say that the platter is spring loaded. The platter is two concentric pieces,an inner piece that is about the size of the record label or a little wider in diameter, and an outer which goes all the way out to the periphery. The inner and outer platters are linked by flexible thin metal fasteners that act sort of like a spring to decouple the two sectors . This was Denon’s way of isolating the platter from the bearing, since the playing surface of the LP is almost entirely supported by the outer platter. I have a DP-80 too. My platter differs markedly from your description: the "inner piece" is not the size of the label, it is the size of the LP. The playing surface of the LP is entirely supported by the inner platter, not the outer. The outer is directly coupled to the main bearing/motor. It may look otherwise to a casual glance, but there is a clear gap (±1mm) near the edge, separating the inner platter (11 5/8" diam) from the outer — the outer platter is just a silver rim 3/8" wide, though 99% of its mass is hidden beneath the inner. The springs are only half of the suspension. There are also foam pads (9 of them IIRC). Like all foam from that era, they decompose, crumble, rot (just like old speaker surrounds) and no longer provide the intended decoupling or resonance-damping. You cannot see them without removing the leaf-springs and separating the two parts of the platter, so you may not know they’re there, or their condition. But if you had it completely rebuilt, I’m sure the technician took care of it. The discrepancy between our platters confuses me. I’ve had it apart (to replace the rotten foam pads) so know it rather well, and just looked again. If you have time, could you take another look at yours, and confirm the inner part is label-size? If it is, Denon must have made differing platters, which would be very intriguing. |
@chakster And you just received it, yes? it’s beautiful, of course.
But your mat is not like mine! Now I’m worried: it’s said to be "carefully engineered for the DP-80" etc. I don’t know how much that matters, but...
Mine came with the table, from an eminently reputable dealer, in a massive VPI plinth, but with the best will in the world, mats get switched.
Mine says "Denon" on the back, molded in the rubber. Yours is markedly different. I have one that closely resembles yours; more concentric rings, and lighter in weight — but of course that doesn’t mean it is like yours. "SFTG170M01" appears on the back of it; does yours have any signifier on the back?
I checked 50 or so pictures on Google of various DP-80s; there’s a variety of mats, including some silly mismatches — but over half look like mine.
Another question: do you know about the state of the foam pads (described in my post above)? Did the seller mention them, or any other info of recent maintenance/renewed parts? |
...but honestly i don’t care about it, can’t remember when i’ve been using a rubber mat last time, normally i replace them with my favorite SAEC SS-300 (lightweight) or heavy Micro Seiki CU-180(or superheavy CU-500) depends on the turntable torque and platter. @chakster I have the SS-300 too, and use it on most TTs, preferring it to rubber. But there's an issue with the DP-80. The platter is in two parts, isolated from each other, to keep all bearing/motor noise from reaching the inner part where the LP/stylus do their thing — it's quite different from the split-platter on an LP12 and others where the 2 parts are in direct hard contact with each other. Both the 300 and CU-180 interfere with the platter's design. Though the DP80 has ample torque for the CU-180, it interferes the most. I suggest the SS-300 is better suited: it has a cut-out on the underside at the edge, so it doesn't contact the outer platter at all. |
The foam in all original ones are gone by now - there’s a suitable replacement available at Home Depot for $3 available - cut it into 0.875 lengths put it in place you will have 8 feet left. @pbnaudio I used weather-stripping to replace mine — is that what you mean? It's the foam-with-adhesive for sealing windows, doors, etc.* I had 4 or 5 rolls already, various sizes — one of them seemed the right width and thickness (they compress a bit, so thickness matters — too much compression, they become like hard rubber and no longer isolate; too little, and they do nothing at all). But they also come in different densities, from very spongy to quite firm. Which density, width, thickness do you recommend Peter? It seems many of the DP-80s in this thread may need it, and it's a fairly easy DIY. * Ironically, I never used any of them for insulation. Only for Audio; one of the many useful 'tweaks' at your local hardware. |
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! |
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.
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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. As I mentioned, I didn’t have the manual at the time. Denon no doubt preferred you take it to a trained Denon tech with all the parts and tools, but is that possible 40 years later? But removing those bolts/leaf-springs is the only way to renew the foam pads: you can't even see them otherwise (some owners don't know they're there). Even if your TT is NOS (lucky you!) I suspect they’re gone. Age and air destroy them, not years of use. The thing is, the split-platter design really works! Before-and-After was a big difference, so I consider new pads essential. You can even "feel" the difference when you squeeze the two platters together. Other split-platters (eg Linn, Thorens) only do it so the motor/pulley can be farther inboard, under the platter, allowing a smaller turntable. There’s no sonic benefit — though an easy mod can turn it into one. There’s only one issue I’m aware of with the DP80: centering the platters when putting them back together. You know how to do that, and I described my method above. There’s one other thing — retightening the bolts securing the leaf-springs. IIRC, they were torqued tight, and should be torqued tight when reassembled. BUT I decided not to. I felt I understood the suspension principle after working on it, and chose a different tension for the leaf-springs. But I won’t get into that: some people might jump on my head. If’s definitely a modification — whereas the pads are a simple replacement of failed old parts. |
I have 2 1000W step/down/up transformers — and never use them. No need. I live in the US and most products — Asian, British, European — make US versions because the market is so large. At present I need only one, for my DP80, and it can be very small: more convenient, smaller than my SUT. The only other time I recall that I needed a big transformer was many years ago: a 100V Luxman tube integrated, never imported here.
If I lived overseas, however, it would be as essential to a good audio system as an amplifier. I was planning to live elsewhere, and acquired a whole collection for that purpose, maybe 20 in all, from very big to small. But sadly that relocation didn’t happen. Though born and raised here, my country, as it is now, doesn’t feel like home. |
@pbnaudio thanks Peter. BTW: how do you lubricate DP80 motor?
The bottom bearing "holding" plate comes off by removing 3 screws, so its pretty easy. What lubricant do you suggest, Peter? |
