Plinth ideas for DENON PD-80 DD turntable

Cool, thanks ! 

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

Another useful trick was with 2 red screws (under the platter) to let the DP’s own transformer move down for an inch or so.

Of course, all my turntables (except 2) are 100 volt and i have 1000 watt step down transformer for japanese electronics, another 110 watt transformer for US made electronics. And the power socket produce 220/240 volt here :)

I am very well prepared for all voltage standards in the world. My step down transformers are heavy as two bricks each. They are, however, so called "auto transformers" and i’m thinking to upgrade one of them which connected to my First Watt 110v amp.

Local company just relesed the upgraded version of step down trans for audio, which is different from my classic auto-transtormer from that comany.

"Unlike the auto-transformer, the transformer provides galvanic isolation of the load circuit from the mains. The transformer acts as a filter for impulsive noise arising in the primary network."

Many local folks using Japanese Toyozumi transformers, but most of them are also auto-transformers.

My powerful stepdown transformers produce 50Hz, i’ve noticed the trick with DP-80 switch earlier when i received it and checked online, mine was set to 60Hz before.

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.

  are 100 volt and i have 1000 watt step down transformer

have you the brand or link for research?

@best-groove Those russian toroidal step-down transformers are cheap:

Here you can find 1600w version, i use the same, but 1000w.
They are all available for japanese (100v) or for american (110v).
Stepdown auto-transformers from 220/140 to 100 (or to 110v) depends on the version. 

New models designed for audio:
"Unlike the auto-transformer, the transformer provides galvanic isolation of the load circuit from the mains. The transformer acts as a filter for impulsive noise arising in the primary network."

you can read here about 100w version and here about 400w version.

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.

I wish someone can spread the light on step down transformers subject. 
I've been using cheap and small (made in china) before, but upgraded to the big and heavy local monsters long time ago. I use powerful stepdown transformers, because i connect at least 2 turntables to each stepdown device and i want to be abble to connect even 4 turntables to ONE stepdown trans if needed. 

The majorty of step-down transformers on the market are "auto-transformers" according to their internal construction, i don't know if the term "auto-transformers" is what you use in english. 

But i'm curious why another principle is better (especially for the amplifiers)? As the oppisite to auto-transformers there are different ones with "galvanic isolation". 

"Unlike the auto-transformer, the transformer provides galvanic isolation of the load circuit from the mains. The transformer acts as a filter for impulsive noise arising in the primary network."  

Personally i'd like my stepdown auto-transformers to be a bit quieter, but i think for a turntable stable vontage is much more important. I don't use any power conditioners in my system. 

@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?

Chakster from the text you quote, it seems that the new product is a “real transformer“ in that it has a primary and a secondary that are discrete from each other. This provides the mentioned galvanic isolation. What you have been using sounds like an autoformer. An autoformer has certain advantages over a transformer in some applications, but probably not for simply stepping down the voltage. 

I use a 50 W step down transformer that I purchased on eBay it is conveniently small. I have one each for my L07D and for my Dp80. Even 50 W is overkill.

@lewm don’t forget that you stepdown from 110/117 to 100v, but i must stepdown from 220/240 to 100v like everyone in Europe.

From what i’ve read the stepdown device must be at least 3 times higher in wattage compared to the actual source (turntable). For the amps the power of stepdown trans definitely must be much higher as far as i know.

I have no problem with mine, each one is 1000w, but as i said i use just one trans for everything japanese and another trans for everything american. I can connect 2-5 devices to each stepdown trans.

I’ve been using a cheap 30w max "super" stepdown autoformer before (it looks like power adapter), but the price for those chinese stepdown devices was nearly the same compared to 10-20 times more powerful local made autoformers people using here for japanese and american audio electronics. So i went for the powerful, the equal autoformers made in USA cost $500 (local made cost under $100).

Japanese stepdown devices like Toyozumi CD240 (or KD1000) are also autoformers and cost 3 times higher. They are very popular here.

But seems like real transformer with galvanic isolation is always better for critical audio devices, especially for amps. And safer for the user.

P.S. I know nothing about technical aspect of the step down transformers and about impact on the audio, i believe it is far more important for the amps than for the turntables. I'd like to have one stepdown for everything (universal), not many different stepdown devices. 

I use Royal Purple Synthetic lubricant for lubrication of the bearings.

https://www.royalpurple.com/product/synfilm-recip-100-reciprocating-air-compressor-oil/

Good Listening

Peter 

I have one from KAB recommended for Technics, he's got another one at the moment  on his site for $5.95 (scroll down for SFWO 010 oil). 

"This is the official original SFWO 010 oil. Anderol 465 aircraft quality synthetic acknowledged by Panasonic to be the original factory reccomended oil for all Technics turntables. It is great for all steel/brass/bronze bearing spindles as well. Now being supplied in a long narrow stem pipette to easily reach into tight spots."

  

I'm absolutely loving this thread especially given that I am eventually gonna get round to finishing off two plinth projects for a: 

Sony TTS 8000
JVC QL10 (TT101)

I have effectively two designs in mind.

I have thus far made two 'aerolam' style planks using aluminium plate sandwiching aluminium honeycomb

I unfortunately messed up a aluminium Panzerholz sandwich (I do have another plank)

My intention was to make a plinth using:

Top plate aerolam sandwich
Subchassis aluminium Panzerholz chassis
corian side cheeks (bright orange to look like the PSx9)
lexan supports from top plate to sub-chassis 

My other thought was to try and either emulate 

A. Townshend Rock reference - Bitumen, plaster of Paris (and anything else you know goes into it)
or
B. Sony TB2000 style - don't know if I can make a bulk mould compound.

I am getting the TT101 serviced but thankfully have a QL10 base - I'm wondering if that plinth is actually any good.

Love to hear your views.

I am getting the TT101 serviced but thankfully have a QL10 base - I'm wondering if that plinth is actually any good.

@lohanimal Interesting, who's responsible for servicing ?
I have two TT101 

Searched for TT101 plinth ideas i've come across interesting project of our audiogon fella, this is how it looks like in his blog: 

1) TT-101 with one tonearm 
2) TT-101 in ring plinth with two tonearms, here is a different view
3) TT-101 in ring plinth on isolation platform with two tonearm pods. 
I think the ring is slate ? 

Recently discovered two granith cylinders at home that can be used for toneam pods. And my pneumatic AT616 feet to support up to 60kg already here. 

@chakster 

Hi Chakster

I have that page saved as a favourite - I am not who the owner of that web sight is but he is a man of both great wealth and taste :) 

I used Wilkinsons I the UK - boy are they slooooooooowwwwww. That said I am awaiting delivery.

going a bit off topic - I am intrigued whether the new SP10 is better than the original mark 3

There's something so addictive about these DD's.

The chap who created the Direct Drive Museum and others on this forum say that all the DD's of the 70's era sound quite similar and are all  effectively cut from the same sound cloth.

All said the chap on the Vintageknob rates the JVC highest.

Anyway I digress

Have you settled on a design, or are you buying a plinth?

@lohanimal  Hey, regarding my Denon DP-80 i am happy and surprised by the quality and weight of the original Denon DK-300 plinth (about 15kg) with dust cover. This design is great. I will stick to this plinth for some time for sure. 

As for the Victor TT-101 project i'm thinking about custom made solution in the future. It would be nice to read your comments after you will get you TT-101 from UK, i hope Andy at Wilkinson can train on various TT-101 

back to denon:

First picture of my Denon DP-80 system.
The drive is not screwed in DK-300 yet, the DA-401 arm is not mounted on the armboard yet, but everything looks nice together. 

The armboard on dk-300 plinth is exact same color as the plinth itself, so any other armboard (different material and different color) is probably not a good idea in terms of design. I was thinking about spare metal armboard for the future. 

   

While on the Plinth subject you can see in the my systems pg
a constrained layer 90lb Rosewood wrapped example
I put together for my TT-101.

Will accept all arm lengths with 3 arm boards which also 
elevate using spacers in their threaded fittings.

Peter @pbnaudio  Great meeting you Saturday for music and conversation - I will be in touch for DP-75 rebuild….

Best

Jim

Great thread guys!

@pbnaudio +1

I use Royal Purple Synthetic lubricant for lubrication of the bearings.

https://www.royalpurple.com/product/synfilm-recip-100-reciprocating-air-compressor-oil/

The industrial lubricants from RP are exceptional. They have ISO viscosities for any application and their UPG grease is a go to for inverted spindles or loose bearings.