Monsterizing a Denon DP-80

[soundofvoid]

I had been aproached by a fellow audiophile who wanted to make a killer TT
without breaking the bank (sub 5000 euro).
He was already using a nice german made turntable (that many would dream of)
but he (and I) thought that his sound was not as it should be.
He had tried many cartridges and three phono stages but he was still unhappy.
After listening to my analog combo he decided to completely alter his set up.
The limit was 5000 euro all included (turntable, arm, cartridge,phono stage).
If you want to make something really good for this kind of money,a nice plan
is paramount!
Since his main part of Lp's were 70's-80's rock, i proposed to him to escape from the belt driven camp and move to the DD one.
For some strange reason DD ones always seem to me to nail down rock/dynamic music better than belt driven turntables.I have some ideas on the subject but i will not discuss them now...
At first he thought that this was a stepback but he changed his mind
when i showed him what i was considering.
The Denon DP-80 is an 80's workhorse with known good and bad points.
The good ones:bidirectional servo,a 3 phase out motor that can move mountains,a very well damped (two metal part with interdamping layer) platter,easy layout,quality construction.
The bad ones : only 100VAC (Japan only version),hard to find a clean well maintained unit,the underside is prone to sound reverberation...
We had to find the "naked" version that was sold to radio stations
or audiophiles who wanted their own type of plinth because i was going after a design that was going to cure as many as possible of the known flaws.
So our quest for finding such a nice unit started ... and was fruitfull after
3 months or so when a nice specimen was bought through ebay from a german lady whose's late husband had an eye for good things audio
(judging from what else she was selling).
He had quite a collection of turntables and the Denon obviously was sharing duties with other sources which meant that it was a low hours unit.
It arrived at my office nicely packed,totally unscratched,with the Denon manual and the cutout schematic!
Total cost:1000 euro.
You have to see and hold one of these in your hands to fully appreciate
the quality of construction involved.My friend was stunned with its
flying saucer looks and it's sheer size!
Fot those not familiar please see the pictures:
a)Denon DP 80
b)Denon DP-80 on thevintageknob.org

[soundofvoid]

I had to design a base that would :
a)Add mass to the 10Kgs or the DP-80.
b)Dampen the underplatter constuction
c)Eliminate any other (internal) potential source of vibration.
d)Deal effectively with external vibrations.

I opted for a modular construcion that constituted from four slabs of aluminum, each 3 cms thick.
Those were going to be milled in a circular design (as opposed to the classic Denon "rectangular with lid" wooden chassis).
Each slab was going to be cut according to the "cut out" plan of the underside mechanism with a clearance of 3mm.

Some form of decoupling/damping would have to be implemented between the four slabs of alumimum in order to gradually filter the upward going vibrations from reaching the platter.To be discussed later...

As supporting feet i designed three (10cm in diameter) bronze cylinders that would end on inox steel spikes with cups.
Their connection with the four aluminum slabs that would form the chassis, was to be evaluated...

Another 10 cm bronze cylinder would serve as a tonearm base.
It would sit on a slightly wider inox steel bottom and on the top
i would incorporate a top plate cut to the footprint of the tonearm used.
If a different tonearm was to take service, all that was needed is to CNC a different top plate keeping the costs to a minimum.

[Charles Darwin]

For €5000 or a lot less you could have just bought a s/h EMT 950 which already includes phono pre, arm and cartridge.

Not very diy but you won't get a better deck.

[soundofvoid]

That's great Charles,if you like the vintage look and can stand having an EMT in your living room.
Personally i'm more into a more modern look.
The used market is full today from high priced units of passed years.
That doesn't mean that someone willing to make something really individual
won't make the effort...
Just wait and you'll see what i am talking about!

[dnewma04]

Is the project complete or at all past the design stage?

[soundofvoid]

As the design of the turntable was advancing, other issues regarding the turntable
had to be addressed.
After discussing with my friend various options about the tonearm that we could use,
we have made a shortlist of arms that we would try buying from ebay.
He had set his sights on the likes of SME,and VPI.
I suggested to look also for a WILSON BENESCH or a DYNAVECTOR.
Our limit was 1000 euro which was a tight margin for such items.
Needless to say that we have bidden on several examples and lost.
After a while i noticed an auction for a Dynavector DV-505 being on sale from a Danish audio store.The auction was running for three weeks with no bids.
He was asking for 1100 euros.
I contacted him, and after a few emails we got it for 1000 euro, including the shipping
and insurance costs.
It was a rare light blue version and arrived in it's original package looking in very good condition.
The cable to phono was replaced with Van den Hul D-501 Hybrid and the short headshell
wires and tonearm wires with the Van den Hul MCS 150-S solid silver cable.
Luckily (in the Dynavector site) we could find for download all the details of the rectangular base of the arm.We decided to keep the other parameters unchanged and make a similar round plate out of solid inox steel.
And that took care of the tonearm part...

[soundofvoid]

The project is complete.I just like to describe the paths taken...
Soon i will post pics.
Be patient.I think that you will be rewarded!

[soundofvoid]

And this was the first scetch of the final design after we had bought the Dynavector arm.

[soundofvoid]

And this was the first "artist's rendering" of the final looks.

[soundofvoid]

We have decided on a soft type of aluminum for the 3cm thick aluminum slabs.
Each one was CNC cut and milled to accomodate the shape of the turntable
mechanisms plus the supporting legs.
When all main part aluminums where cut we had to decide on the material between them.
After testing sheets of different absorbing/dampening materials and their behaviour after being compressed between the aluminum parts,
we decided to use a sheet of soft pliable silicone that i had also used in other
projects.
That can be found in progressively thicker sheets.
Since my friend wanted to have (for aesthetic reasons) 3mm solid inox rings between the aluminum parts i opted for a slightly thicker 4mm silicone sheet
that would reduce it's thickness to 3mm after being compressed.
This way we had a massive well damped body for the DP-80.
The "feet" were cut from bronze ( i love to mix metals!).
They were 10 cm in diameter drilled hollow about to a 5cm radius so we could
tight the screws that connected them to the main chassis.
They were connected with two screws with the second and fourth aluminum
part of the body so that the first part was decoupled from the feet.
The feet were then going to be filled with sand or lead shot (or both) and close with a screw on tap made from inox steel.
The same "hollow" approach was followed to the tonearm tower.
See some pictures from the construction days...