Rogers Cadet III modifying pick up adapter for magnetic cartridge
 

I have a Rogers Cadet III amplifier and have recently got hold of a
Thorens TD 160 turntable that I would like to try with it. The Cadet
only has a pick up adapter for a ceramic cartridge, I want to try and
modify it for use with a magnetic cartridge.

I have a copy of the circuit diagram for the control unit but it doesn't
include the pick up adapters.

I've taken a picture of the adapter in the hope someone might be able to
advise how to alter it for a magnetic cartridge, and uploaded the
control unit diagram + description of the magnetic cartridge adapter
from the manual:

http://www.apax63.dsl.pipex.com/puadaptor.jpg

http://www.apax63.dsl.pipex.com/ControlUnitCircuit.jpg

http://www.apax63.dsl.pipex.com/page2.jpg

I notice the magnetic adapter is supposed to be RIAA, I'm not sure how
important that is, or what additional circuitry it would require.

Thanks for any help
Tom

--

apax63 'at' dsl 'dot' pipex 'dot' com

Rogers Cadet III modifying pick up adapter for magnetic cartridge
 

"Tom" wrote in message
...
I have a Rogers Cadet III amplifier and have recently got hold of a
Thorens TD 160 turntable that I would like to try with it. The Cadet
only has a pick up adapter for a ceramic cartridge, I want to try and
modify it for use with a magnetic cartridge.

I have a copy of the circuit diagram for the control unit but it doesn't
include the pick up adapters.

I've taken a picture of the adapter in the hope someone might be able to
advise how to alter it for a magnetic cartridge, and uploaded the
control unit diagram + description of the magnetic cartridge adapter
from the manual:

http://www.apax63.dsl.pipex.com/puadaptor.jpg

http://www.apax63.dsl.pipex.com/ControlUnitCircuit.jpg

http://www.apax63.dsl.pipex.com/page2.jpg

I notice the magnetic adapter is supposed to be RIAA, I'm not sure how
important that is, or what additional circuitry it would require.

Thanks for any help
Tom

--

apax63 'at' dsl 'dot' pipex 'dot' com

I'v tried to find a circuit diagram of the RIAA adaptor, but no luck. If
no-one else has one, you could buy an external RIAA pre-amp (The QED DS1 is
around £35, ) which should feed the Flat Ceramic input OK. Ideally, you may
need 10dB attenuation on the RIAA pre-amp output. The DS1 provides 175mV out
from a nominal 5mV in, so should drive the Rogers 65mV input reasonably OK.

S.

Rogers Cadet III modifying pick up adapter for magnetic cartridge
 

Serge Auckland wrote:

"Tom" wrote in message
...
I have a Rogers Cadet III amplifier and have recently got hold of a
Thorens TD 160 turntable that I would like to try with it. The Cadet
only has a pick up adapter for a ceramic cartridge, I want to try and
modify it for use with a magnetic cartridge.

I have a copy of the circuit diagram for the control unit but it doesn't
include the pick up adapters.

I've taken a picture of the adapter in the hope someone might be able to
advise how to alter it for a magnetic cartridge, and uploaded the
control unit diagram + description of the magnetic cartridge adapter
from the manual:

http://www.apax63.dsl.pipex.com/puadaptor.jpg

http://www.apax63.dsl.pipex.com/ControlUnitCircuit.jpg

http://www.apax63.dsl.pipex.com/page2.jpg

I notice the magnetic adapter is supposed to be RIAA, I'm not sure how
important that is, or what additional circuitry it would require.

Thanks for any help
Tom

--

apax63 'at' dsl 'dot' pipex 'dot' com

I'v tried to find a circuit diagram of the RIAA adaptor,

I didn't think to call it an RIAA adapter, searching for that has found
something, with a description of the circuit:

http://www.diyaudio.com/forums/showt...threadid=28284

-Its its wired symmetrically , pins 1 to 4 away from the earth (0).
-
-resistor : blue - grey- orange - gold : pins 1 and 3. (68K 5%)
-resistor : voilet - red - yellow - gold : pins 2 and 3. (720K 5%)
-capacitor : polystyrene - 680P - 5% - 350V : pins 2 and 3.
-capacitor : polystyrene - 2500 - 5 - 400V : pins 2 and 4.
-
-I assume the 1st capacitor is 680pF.
-
-I think (and the size agrees) for the second capacitor the last
-digit is a power of 10 multiplier for PF = x1 = 250pF.
-The 5 I assume is 5%.

Does that sound right? I'm going to have a go at building it.

you could buy an external RIAA pre-amp (The QED DS1 is
around £35, ) which should feed the Flat Ceramic input OK.

I had thought of something like that, that would be an alternative, but
would be better to go direct to the amp if possible.

Looks like a trip to maplin tomorrow :-)

--

apax63 'at' dsl 'dot' pipex 'dot' com

Rogers Cadet III modifying pick up adapter for magnetic cartridge
 

"Tom" wrote in message
...
Serge Auckland wrote:

"Tom" wrote in message
...
I have a Rogers Cadet III amplifier and have recently got hold of a
Thorens TD 160 turntable that I would like to try with it. The Cadet
only has a pick up adapter for a ceramic cartridge, I want to try and
modify it for use with a magnetic cartridge.

I have a copy of the circuit diagram for the control unit but it
doesn't
include the pick up adapters.

I've taken a picture of the adapter in the hope someone might be able
to
advise how to alter it for a magnetic cartridge, and uploaded the
control unit diagram + description of the magnetic cartridge adapter
from the manual:

http://www.apax63.dsl.pipex.com/puadaptor.jpg

http://www.apax63.dsl.pipex.com/ControlUnitCircuit.jpg

http://www.apax63.dsl.pipex.com/page2.jpg

I notice the magnetic adapter is supposed to be RIAA, I'm not sure how
important that is, or what additional circuitry it would require.

Thanks for any help
Tom

--

apax63 'at' dsl 'dot' pipex 'dot' com

I'v tried to find a circuit diagram of the RIAA adaptor,

I didn't think to call it an RIAA adapter, searching for that has found
something, with a description of the circuit:

http://www.diyaudio.com/forums/showt...threadid=28284

-Its its wired symmetrically , pins 1 to 4 away from the earth (0).
-
-resistor : blue - grey- orange - gold : pins 1 and 3. (68K 5%)
-resistor : voilet - red - yellow - gold : pins 2 and 3. (720K 5%)
-capacitor : polystyrene - 680P - 5% - 350V : pins 2 and 3.
-capacitor : polystyrene - 2500 - 5 - 400V : pins 2 and 4.
-
-I assume the 1st capacitor is 680pF.
-
-I think (and the size agrees) for the second capacitor the last
-digit is a power of 10 multiplier for PF = x1 = 250pF.
-The 5 I assume is 5%.

Does that sound right? I'm going to have a go at building it.

you could buy an external RIAA pre-amp (The QED DS1 is
around £35, ) which should feed the Flat Ceramic input OK.

I had thought of something like that, that would be an alternative, but
would be better to go direct to the amp if possible.

Looks like a trip to maplin tomorrow :-)

--

apax63 'at' dsl 'dot' pipex 'dot' com

Looks reasonable to me, so have a go. If I were you, I would also buy a pair
of 2500pF capacitors, and try it both ways. Whatever, you won't do any
damage if the capacitor values are off, just won't sound right!

S.

Rogers Cadet III modifying pick up adapter for magnetic cartridge
 

Maplin currently sell a phono preamplifier for £15 if price is an
issue.