Facelift for a Dual 505-2

[Larry365]

Hi,

I am a newbie here and this is my first post regarding a turntable project based upon the budget 1980's Dual CS505-2.



I will be documenting the work during each stage with text and photos. My aim is to give this well regarded budget turntable a much needed facelift to improve the sound and looks.

Here is the underside without any modifications:


These are some of the proposed modifications:

[c2cthomas]

Hello Larry - and Welcome to diyAudio!!!!

I like the way you are thinking!!!! Very nice 1st post and I will watch this with interest....

[sreten]

Hi,

I have played around with two Dual decks trying to improve the sound,
and TBH whist some improvements are possible, the basic nature of
the decks still remained, I couldn't really make them fly.

I don't think removing all those parts is a good idea. No autoswitch on,
no autoswitch off /arm lift and the end of record, no cueing lever, is
hairshirt stuff not really suited to a basic decent budget turntable.

Why you'd want to remove the transit screws is hard to fathom.

You can free up the suspension horizontally by cutting 4 nylon tangs
out of each suspension spring. Note that you can't add appreciable
mass for damping to the top plate or the platter without upsetting
the balance of the springs. I think a 500g mat was ok though.

You can check the arm for freeplay in the bearings and adjust if needed.
You can glue (araldite) in the main bearing to effect I recall.
You can strip the top plate and spray the underside and the platter
recess with bitumastic car underbody spray, then put the stuff back.

You can use the same stuff on the inside of the base plinth.

You may have to add a hole with a bolt and some steel washers
near the motor to get the suspension to sit flat again though.

I don't want to put you off, but in my experience you'll learn more
about what can't be improved in some turntables more than what
can if you try to go OTT on a Dual CS 505.

rgds, sreten.

[Larry365]

Thanks for the replies and welcome. I forgot to say that all of the parts being removed are for convenience of use and add nothing to the sound quality; the stop start via tonearm cueing, and the arm lift.

The speed change and pitch control are being left but anything else that adds questionable resonance or weight to the top-plate will be discarded. Likewise, a new plinth will be made from solid wood and the flimsy plastic base tray and suspension holders will also be discarded.





The suspension will be revised as the top-plate will be cut to allow a slightly de-coupled, VTA adjustable armboard to be installed. Still having thoughts about using the ULM arm or Linn LVX. The current wiring method is awful.

[Larry365]

The power comes into the plinth next to the outgoing phono (rca) cable. It then feeds a PSU board which is hidden by a vented plastic cover. The board also has the pressure switch on it that is pressed in by the mechanical levers when the tonearm is moved across the platter. It is released when the tonearm reaches the end of the record position. The motor has four wires which are attached to the circuit board.


This board will be moved out of the plinth and into a dedicated PSU box, the pressure switch will be removed and replaced with a single pole rocker switch. When the 4 core feed for the motor is run into the plinth it will be isolated from vibration. Here is a photo showing the PSU box before fixing and modification, the red crosses show parts that will be discarded.


The aim is to have a manual turntable, devoid of metal levers and bad mechanical vibration yet have the correct mass and resonances to enable the stylus to sing.

[sreten]

Hi,

Yes, well I been there and done it, and have a very good idea what
your suggested modifications will do, and won't do, except for the
revised arm mounting, I never liked decoupling here but YMMV.

I've been rebuilding turntables for ~ 30 years, much more so in the early
years than later years. Faced with a Dual I do know pretty much what
is worth doing and what isn't, you can use that experience or ignore it.

Or more to the point if you stick at it, find out the same things, but I
doubt nowadays you'll ever get the chance to rebuild / modify / tweak
turntables as much as I did in the heyday of vinyl reproduction, pre CD's.

And to be fair, consequently learn from your mistakes and successes.

One thing I will say though is your "analysis" of what will makes things
better is miles off from mine, so perhaps you have to find out yourself,
or not as the case may be, until you've rebuilt a turntable that utterly
slaughters the model its based on, due to your learned understanding.

The problem is understanding only comes with the physics involved,
and quite frankly a lot of commentators on turntable sound are utterly
clueless, turntables IMO have to be understood, like an instrument.

rgds, sreten.

[sreten]

FWIW simply on cost grounds I wouldn't fit an LVX discarding the arm.

[Larry365]

Erm... wow!

I guess that has put me off from sharing this project on-line, what a condescending welcome.

[kevinkr]

Originally Posted by Larry365

Erm... wow!

I guess that has put me off from sharing this project on-line, what a condescending welcome.

Hi Larry,
Please disregard the tone of sreten's comments, and please continue to share your project here. His opinions are just one of many here.

Sreten, you need to cool it, take this for the warning it is.

[sreten]

Hi,

OK I will cool it. Condescension certainly wasn't the intent. As I implied
in my post, I suspected my comments might not be regarded as being
helpful / positive although they are intended to be, in a critical manner.

I don't want to "browbeat" anyone into the way I see things, or put
someone off doing stuff, so it was probably best I kept my opinions
to myself, but hindsight is a fine thing, though I should of thought
about how what I'm saying, and how I said it, might be taken more.

rgds, sreten.