I require two loudspeakers . The first is a 5 inch electrodynamic field coil speaker for early STC Model 55. This is about a 1934 model radio.
The second is for an ELECTROSOUND 524/1 or 524/2.
Regards.
Jimb.

Electro-dynamic speakers are getting like hens teeth. It is often a case of a permag speaker & a heavy wattage resistor.

Marc

Hello again Marc.
Yes I am aware of that however I did want to retain the originality, so I thought I would give it a try.
Regards Jimb.

I may have one that has not been tossed out? I actually went through some that are "WHY?" That came from a now deceased estate. They were that well looked after that probably every last one in that box has a stuffed cone. Any still in the workshop definitely will have issues.

You have another post on this set. That risks miss information and is not a good idea. As I note posts on the American forum. Don't do it there It is banned & will be terminated and I have done it.

Marc

Hello Marc.
Not sure what you mean about another post and miss information and something being banned . I thought what I wrote was straight forward. Was not trying to upset anybody.

Marcc's talking about opening more than one thread on the same subject. It's best to only post the comment once in the most relevant possible forum. That way all replies are seen in the one place. It is called cross-posting. It doesn't happen often enough here to be much of a concern and if I see it in time I'll redirect users to the thread that already has a reply in it. On busier forums they do tend to ban users for doing it.

Hello Brad.
Thank you for your explanation.
Regards Jimb.

Sorry to Bring this up again. I have had this working but never very well.
Can anyone tell me the value of the inductor between the plate of V3 (57) and grid 1 of V4 the 2A5 on the original unmodified circuit of the STC 55. I am also confused with the volume control circuit which biases V1 and V2. I have replaced the reostat because the old one was spotty . What puzzles me is,if I disconnect the wire off the wiper I can measure HT volts on the disconnected wire, if I remove V1 and V2 the volts disappear .looking at the circuit I cannot come up with a reasonable explanation . There are no inter electrode shorts on these tubes .
This radio was in an awful state when I got it ,there are 3 bobbin style inductors mounted on the rear lip of the chassis however I can make no sense of how they ever were connected or why there is 3 of them. I do have the circuit, however a lot of the values are unreadable. The later modified circuit bears little resemblance to the original. A friend fixed up the cabinet for me so I feel I really must get this fixed.
The reason I am back into the audio again was it was weak and distorted I suspect some of the distortion is due to the inductor not been in circuit.the weakness due to biasing problems. I will. Send a picture of the radio
Jimb.

An understanding of the workings of a valve can be really handy when trying to discover why it has gone awry. Without looking at the circuit the wiper of the rheostat will go to the cathode. If you open circuit the cathode that will cause all of the grids and the cathode to go to B+, or damn close to it.

There are twofold risks: One there will be a heater cathode flash-over as the generalisation is a maximum of 20V between heater & cathode;

Second: On valves where there is an electrolytic or LV cap across a cathode resistor. Then it is in peril if Rk goes open. "Caveat Actor" applies if you disconnect things & power it.

Now the inductor: That is an RF choke & may be resonated to the IF frequency. It is to stop RF from the plate detector getting into the OP valve as it will very likely amplify it and use the result to destabilise the whole set. That set has no AGC so too much signal can overload it. Some had a "Local / DX switch the 59 chassis I fixed had its missing. 68pF in series with the antenna (on a switch) fixed that. Too much signal also applies to alignment.

Weak audio can also be a product of a poorly (or not at all) aligned set. Was the IF re-calibrated?

Plate detectors are notorious for distortion: Its voltages & cathode resistor must be correct. On 55 pt 95V; Sc 50V; grid bias -3.2V

There is a Fault finding chart on the service sheet. No RFC is going to cause problems. Modern RFC's for that are Green & the size of a resistor. P/n is not readable. The original volume was 6K in most of that series I had to adjust the bias to suit 5K on chassis 59 as it was distorting & the original setup had been destroyed (hacked).

Marc