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

"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.

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

"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.

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