Hello can anyone tell me how customers used to attach cassette recorders to the fidelity UA4 or other record players of this period where the 5 pin din socket comes directly of the deck/cartridge connections tag. The cassette players cause the audio output from the UA4 to dip significantly . I’ve added 1 Meg ohm resistors in line with L&R outputs to the cassette deck which has helped a lot , but is there another way to deal with this ?
Andrew
@arelectrical That's probably the correct way - some manufacturers used to sell DIN leads with 1.5MΩ resistors in series for just this purpose, to both attenuate the input signal and provide correct cartridge loading.
I used to have to do this with my Grundig C410: the DIN input of which was designed for a microphone so other equipment badly overloaded it. I seem to recall (albeit rather vaguely) that the standard DIN sensitivity figure was 1mV per kilo-ohm so you'd have to do this. I don't have them to hand but I'm pretty sure Grundig themselves sold DIN leads with these resistors.
Some cassette decks did things differently for their inputs depending upon whether you used phono or DIN connections, like my Pioneer CT-F2121. I'll look it up,
@cathovisor Thankyou for your reply I will try a 1.5 Meg resistor in line with each channel & see if this gives the required attenuation. I was thinking of adding a capacitor as well. Any suggestions on what nf capacitor would be neutral as far as the audio is concerned ? I.e in line with L&R channels
Why didn’t manufacturers like fidelity add a suitable resistor during manufacturing They must of known people would want to link an all be it mono cassette recorder to the rear 5 pin din socket . All the record players I’ve seen from this period seem to come of the BSR cartridge tag with bad results when other equipment is connected to the din socket
@cathovisor Thankyou for your reply I will try a 1.5 Meg resistor in line with each channel & see if this gives the required attenuation. I was thinking of adding a capacitor as well. Any suggestions on what nf capacitor would be neutral as far as the audio is concerned ? I.e in line with L&R channels
Why didn’t manufacturers like fidelity add a suitable resistor during manufacturing They must of known people would want to link an all be it mono cassette recorder to the rear 5 pin din socket . All the record players I’ve seen from this period seem to come of the BSR cartridge tag with bad results when other equipment is connected to the din socket
Firstly, manufacturers had no idea what the end user would connect: a valve tape recorder would most likely be fine and there were still enough of those about when the likes of the UA4 were in production. Secondly, Fidelity stuff was made down to a price and any extra components would impact on the profit margin. However, it meant the seller of the UA4 could then sell an appropriate lead to the owner for use with his cassette recorder.
As for capacitors - you don't need them.
@cathovisor Thank you again for your reply. That’s interesting so Valve tape recorders have a different input impedance to cassette recorders so my cartridge loading problem may not of been a problem. Yes I agree fidelity products were very basic to say the least. I understand the output ICs on these were also troublesome if there was a shorted speaker cable, the earlier ic’s not incorporating short circuit protection & made by Texas . Yes ok, I understand a capacitor is not needed but what size is generally neutral as a coupling capacitor at this level of signal ?
@cathovisor Hello basically will have no effect on the audio signal like a coupling capacitor
@arelectrical It's not the level of signal you're interested in, it's the impedance.
The corner frequency is calculated from
1/(2*Pi*C*R)
where C is in Farads and R is in Ohms.
But as I have repeatedly said, you don't need them.
