Dual 504 put to use

[mkusan]

Hello everyone,

My uncle at age of 85 decided to put Dual 504 turntable in use for the first time. Yes, it is new in the box 🙂

He has no speakers or amplifier, so I thought about Edifier R1280T Wired Active speakers to keep it simple for him.

EDIFIER Studio R1280T 2.0 Lautsprechersystem (42 Watt): Amazon.de: Audio & HiFi

However, as these speakers don't have phono preamp I am not sure if they are suitable as is.

I believe turntable has MM cartridge so far greater voltage output, but is it enough?

Kind regards

Marko

 

[Galu]

Have a look at the new Klipsch R-41PM powered loudspeaker system.

It includes a moving-magnet phono stage, which can be switched into circuit via a toggle on the rear of the unit.

Klipsch Reference Base R-41PM Active Monitor Speakers: Amazon.co.uk: Hi-Fi & Speakers

 

[Kay Pirinha]

Does it still have it's original Dual DMS 240E catridge? Yes, this is a MM cart, especially made for Dual by Audio Technica.


Best regards!

 

[GeorgK]

Hi Marko,

you will need a phono preamp to connect a MM pickup.

 

[mkusan]

@Galu

Thank you for recommendation, they look really nice but slightly expensive, he don't want to invest too much.

@Kay

I don't know the answer to that question since I have not yet seen the turntable.

@GeorgK

Yes, after a bit of googling I figured that, so together with speakers I ordered a cheap phono preamp box.

Hama Stereo Phono-Vorverstarker PA 506 (Fur Plattenspieler, Inkl. Netzadapter 230V/50Hz, 300mA, Cinchkabel 0,9 m) schwarz: Amazon.de: Audio & HiFi

126 EUR total, I hope it will serve him nicely. My biggest worry now if turntable will work after sitting for 40 years.

Kind regards

Marko

 

[GeorgK]

126 EUR total, I hope it will serve him nicely. My biggest worry now if turntable will work after sitting for 40 years.

You will probably need a new drive belt.

Georg

 

[mkusan]

You will probably need a new drive belt.

Georg

Hello Georg,

How will I recognize symptoms of old belt?

 

[GeorgK]

Check if the belt sits sloppy or feels sticky.
Aftermarket spare belts should be available I think.

 

[mkusan]

Phono preamp arrived. I opened to install power switch, surprised to see no opamps. Part count seems low for 40EUR 🙂

 

[Galu]

The preamp employs discrete transistors instead of opamps, which many users believe give better results.

 

[mkusan]

The preamp employs discrete transistors instead of opamps, which many users believe give better results.

Thank you Galu, good news then.

I have another question, it seems that turntable has DIN 5 connector on its output and a separate wire for shield. Do you suggest I:

a) buy DIN to RCA adapter
b) cut DIN connector and solder RCA connectors instead
c) change DIN cable for RCA cable and solder on turntable side

Kind regards

Marko

 

[sesebe]

The preamp employs discrete transistors instead of opamps, which many users believe give better results.

You have right but a truly professional preamplifier is not only made only with 3 transistors.



@mkusan: If you are sure that the cable are completely separate into 2 shielded wire that better you cut the cable and put two quality RCA connectors.

 

[Galu]

c) change DIN cable for RCA cable and solder on turntable side

Provided there is access to a handy tag strip on the underside of the turntable, c) would be my preferred option.

And as sesebe states - the DIN lead may not be suitable for taking two RCA plugs, which would rule out option b).

 

[mkusan]

According to the service manual L&R channel are not separately shielded, see below.

What is puzzling is that my uncle over the phone described the cable as combo of DIN+separate shield wire, like picture two.

 

[Galu]

Good - the manual clearly shows how to employ option c).

Have a look to see if the relevant solder tags are readily accessible.

 

[Galu]

Re your edit. Sometimes in the DIN system the shield acts as the ground wire, in which case a separate ground wire is not necessary.

A separate ground wire, if supplied, only needs to be connected if hum is encountered.

 

[MAAC0]

It was common on German gear in the 70's to use DIN (45500 norm) for connecting gear, tape recorders for example used the 5 pins as In / OUT, that's why there is one ground only at middle pin. There were straight (normal connection) and inverted cables (for dubbing for example). I own a Perpetuum Ebner turntable (crystal head and AC127 transistors) and a Grundig TK 146 Reel to Reel with DIN connectors.

 

[PRR]

...a truly professional preamplifier is not only made only with 3 transistors....

It is possible to make a very excellent phono with three transistors.

However 12VDC power is mighty low and casts doubt on the "professional" badge.

 

[Galu]

OK, sticking the word 'Professional' on the front of the preamp is a bit cheeky, but I'm sure that uncle will be more than happy with the performance!

 

[Kay Pirinha]

Provided there is access to a handy tag strip on the underside of the turntable, c) would be my preferred option.

And as sesebe states - the DIN lead may not be suitable for taking two RCA plugs, which would rule out option b).

According to the service manual L&R channel are not separately shielded, see below.
View attachment 710874View attachment 710880

In reality the stock DIN cable is a twin coaxial lead. Both channels may easily be separated and equipped with RCA plugs.
And yes, there's an easily accessible tag strip beneath the chassis, called the muting switch, where one can solder new RCA leads as well. The stock DIN cable features three 2.8 mm Faston blade connectors.
If you have a close look to the left handed drawing, you see a bridge that short-cuts left channel ground, right channel ground and chassis. If you swap to RCA leads, it depends on the actual (pre-)amplifier and the cartridge grounding whether it is best to leave this bridge (and omit the separate ground lead), to cut the bridge from the chassis, but leave it between the channel grounds, and provide a separate gnd lead, or to remove the bridge completely and also provide the chassis gnd lead, of course.


Best regards!