What transformer output volts supply used for cambridge audio C 70 preamp

SOURCE: Audio Amplifier JVC Model A-GX3

If the service manual is not available on the JVC websites then you should just Google search "JVC A-GX3 service manual" There are many websites that archive manuals. You'll probably have to pay for a copy. Why can't you disassemble the unit and see the output transistor numbers first? More importantly how do you know this is the fault?

SOURCE: Using a tube pre amp with my CA Azur 640A?

There are many answers to your questions but Ill have a go with the basics...
Audio connections should be matched.... its called Frequency impedance,.... to get a signal along wires or cables (or Fibre) the Impedance of the cables and wires must be matched to the device they are connected to transfer the signal along the cables without distortion...

Manufacturers provide many sockets on the input side of amplifiers and preamplifiers to allow the consumer to connect various devices of different impedance.

They label these inputs like CD, or Tuner, or PHONO etc etc,

That means if you have a CD player it must be plugged into the CD input socket then the impedance will be correct and the sound will transfer along the CD cables correctly, without distortion..same with the Phono input etc...
You will find on the sound output to the speakers terminals are also labelled 4-6ohm, or 8-10ohm, these are the impedance expected for the coil ratings of the speakers them selves and its important to get the correct speakers to the correct out put terminals...

In your case all you have to do is follow these simple rules and all will be well....you say you have a squeeze box well there probably isnt a port labelled squeeze box so you need to experiment and try out each input port for the squeeze box to see what input gives you the correct sound output...Watch the Phono inputs as these are very sensative to input sound levels and must be treated very carefully as they have a double stage of sound amplification and as such you need to have the volume right down when connecting up the Phono inputs then increase the volume carefully after the cable connections are completed.

If you follow these rules then all will be well,,,,there is no difference if the Pre amp or Power amp is valve or transistor or FET or has IC outputs to the speaker the same impedance rules apply..just treat it as a box with input and output terminals and all the impedance will be taken care of for you...if you read the lables...

You need to connect you signal source to the Preamp inputs the out put from the Preamp connects to the power amp input then the power amp output goes to the speakers. this is a basic configuration for sound systems, there are other variations but are outside this discussion.

Cheers From YUBEUT

SOURCE: SA3 amplifier to move to Europe : capability of the transformer ?

While living in the States I purchased a Bose Acoustimass 10 system but have now moved back to the UAE. As the system operates on 115 volts ONLY I would like to get it work on 240V without having to use a step-down transformer. By changing out the transformer form 115v to 240v will it work or will I have to change any other components within the system. Can anyone help me??

SOURCE: No audio output or output voltage on 70v terminal

it sounds like you have a power supply problem
try and check for a blown diode inside close or
around the transformer.
maybe this will help.