Dual CS 505-4 treble response

[kjello]

Hi all, I have some questions about lack of treble response from my Dual turntable. I think its made 1984.
Many years ago a neighbour gave me a defect Dual CS 505-4 , it has been sitting in my attic for a decade or more until I decided to try make it sing again.
The turntable was spinning, but with speed issues and strong hum in the right channel.
It was quite an easy fix, a good cleaning and lubing, replaced drive- and pitch belt, new signal cable and rca connections, even changed the tone arm internal cabling with new silver leads.

Couldn't resist getting a custom plinth and an external riaa amplifier = Nad PP-2e
Adjusted needle weight around 1,3 grams (tried everything from 1 to 2 grams) and anti skating as good as I can get it.
Bass and midrange is good and no distortion. Both channels, no issues, plays loud and clear. Silent between tracks, no hum or motor noise.
BUT TREBLE is weak! Same in both channels. I have to turn treble on my pre to max to get decent responce. Its still too dull and muffled. Lacks detail and information in the high range.

Could the stylus be 'worn out' ?
Do the MM type cartridges get weaker in time?
Bad combo of riaa and cartrigde?
What brand is the pick up, do Dual make their own?
What do you think?

Best regards
KO

some pics

 

[chris_f]

It is possible the stylus is worn out, cartridges do go bad but they shouldnt get weaker on their own. The RIAA curve is a standard, so the preamp shouldnt have anything to do with it but different cartridges do have different balances tone wise. The ULM68E if I am reading that correctly is an Ortofon OM20, first thought would be to get a new stylus and see if you like it any better. Especially if you are unfamiliar with the age of the current stylus. If you still dont like it I would suggest looking at an AT or Shure, something with a reputation of being heavier on the top end. That OM20 and new stylus would be fairly easy to flip so replacing the stylus wouldnt be throwing money away.

 

[lini]

KO: Which "new signal cable" exactly - and how long is it? And in case that wouldn't be a regular coax type with single inner conductor, how exactly did you configure it?

Why would I ask that? Well, your new cabling might happen to be problematic in terms of capacitance...

Greetings from Munich!

Manfred / lini

 

[kjello]

KO: Which "new signal cable" exactly - and how long is it? And in case that wouldn't be a regular coax type with single inner conductor, how exactly did you configure it?

Why would I ask that? Well, your new cabling might happen to be problematic in terms of capacitance...

Greetings from Munich!

Manfred / lini

Just replaced the old standard phono cable with an Tara Labs rca cable around 1 meter,

 

[olddude55]

It's beautiful, at any rate.

 

[Legrace]

Your cartridge is a limiting factor.

 

[lini]

Your cartridge is a limiting factor.

I wouldn't quite concur. I mean, granted, one can go even higher in quality, but a ULM68E/OM(B)20 already is a pretty adequate cart for a 505er and definitely shouldn't still sound muffled with a treble boost of +6 dB. Hence it would seem very likely that either the needle isn't good anymore or the load capacitance is off...


KO: Does Tara Labs provide specs for that cable? Oh, and btw, the ULM68E/OM(B)20 actually is a VMS-type MI. And as you had asked: As far as I'm aware, Dual has never manufactured any MMs, MIs or MCs - they did make their own crystal/ceramic carts, though. Whereas the Dual-labelled MMs, MIs and MCs all came from AT, Ortofon and Shure.


Greetings from Munich!

Manfred / lini

 

[kjello]

I wouldn't quite concur. I mean, granted, one can go even higher in quality, but a ULM68E/OM(B)20 already is a pretty adequate cart for a 505er and definitely shouldn't still sound muffled with a treble boost of +6 dB. Hence it would seem very likely that either the needle isn't good anymore or the load capacitance is off...


KO: Does Tara Labs provide specs for that cable? Oh, and btw, the ULM68E/OM(B)20 actually is a VMS-type MI. And as you had asked: As far as I'm aware, Dual has never manufactured any MMs, MIs or MCs - they did make their own crystal/ceramic carts, though. Whereas the Dual-labelled MMs, MIs and MCs all came from AT, Ortofon and Shure.


Greetings from Munich!

Manfred / lini

Thank you for all input
Would you consider Ortofon OM 40 Super a good replacement cartridge for the 505-4 ?

 

[lini]

KO: Actually I'd first suggest you to invest in a priceworthy C-meter (like for example a Mastech MY6013A or like this one, offered by Pollin over here, of which you might be able to find a differently labelled version from a Norwegian electronics vendor: https://www.pollin.de/p/digitales-kapazitaetsmessgeraet-km-20mf-830511), so you can properly determine the capacitance of your phono cabling.

Well, and regarding the OM40Super: Iirc, the original ULM68E/OM20 already isn't quite optimal for the 505-4 in terms of body height, although I'm not quite sureabout that anymore - and the needle of the equally high OM40Super would rather be more SRA/VTA-critical than the DN168E/needle 20. So you'd best have a look at your 505-4 from the side: Does the armtube show a slight rise from the pivot towards the cartridge? In that case, due to the 505ers not sporting adjustable tonearm height, I'd rather suggest you to consider a less high cartridge, especially as that possible upwards slope of the arm is the more problematic one, because compensating for that via slightly lower tracking force (than the suggested value by Ortofon) would cause a lower tracking ability.

Greetings from Munich!

Manfred / lini

P.S.:As I can't properly see that on your pics, do I correctly assume that you're using the original rubber mat (which is a pretty good one, btw...)?

 

[kjello]

From what i can measure by eye the arm is totally flat leveled, I'll have a closer look at that though, Im using the standard rubber mat yes.
I had to change the std phono cable due to hum from a broken earth connection lead I belive.
The Tara Labs is a standard mid level 1 meter copper rca cable, I have others i can try, but if I understand you correctly the turntable low level signal is dependent on a low capasitance cable, between tt and riaa step.
I will look into the c-meter, it was not very expensive I think.
From what I can find out the cartrdidge and needle is both std from 1984, and probably run a lot of of miles.

 

[chris_f]

Most of their cables have the capacitance listed online, though having a capacitance meter is handy.

https://www.taralabs.com/ours-vs-theirs

 

[kjello]

Thanks for all the input.
I got an new Ortofon OM40 Super cartridge and I like the sound very much now, more detail and sparkling highs. I can reinstall my RC-995 preamp which dont have tone controls. All good for now