Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
Thanks
Lode Swinnen
: Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
: Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
: Thanks
: Lode Swinnen
: : Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
: : Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
: : Thanks
: : Lode Swinnen
: : Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
: : Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
: : Thanks
: : Lode Swinnen
Lode,
I have a Radiola horn and the driver assembly is marked with a "P" on one terminal and a "+" on the other. This is so that the small DC plate currents of around 5 ma do not weaken the permanent magnets over extremely long periods of use.
For the amount of time that we run these old speakers it may not be a problem. You have me thinking now however and I will use the right hand electromagnetic theory to determine if there is a correct way. Also old headphones would be the same. My Brandes headphones are marked with a "+" on one terminal. It is interesting however that my RadiolaIII andIIIa radios have no markings to indicate which is B+.
The currents going through these speakers is so low that only shorting the plate side to ground by accident should cause any harm. 90 volts across a coil would cause harm. The normal volage across a coil is i to 2 volts.
The skematic for the Radiola 33 shows a hook up using an ouput choke and capacitor. This is on the nostalgiaair site.
Dan.
Some radios have DC current from the output tube going though the speaker. This can have an effect on the magnetic field of the horn. Current through the speaker coil makes an electromagnetic.
To eliminate this effect connect the speaker to the output tube through a 1 mfd capacitor. Then add a choke or resistor from the plate of your output tube to B+. As a resistor, 2.2 - 3.3K @ 2 watts will usually be ok.
Norm
: I have been unable to figure out how to determine the polarity of horn speaker connections. It seems to matter, in that incorrect connection could weaken the permanent magnet. Some horn speakers have a solid wire and a striped one; in some the wires are identical; in some the leads are missing.
: Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
: Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
: Thanks
: Lode Swinnen
If you are looking at maintaining historical accuracy, the solid wire would be the "-" connection.
Phasing is not a real issue until you are putting more then one speaker into the circuit, and even then it is not going to effect the radio if the loading is correct for the output stage, but it will potentially effect the sound in the room- but you start getting into wave propagation and physics.
: I have been unable to figure out how to determine the polarity of horn speaker connections. It seems to matter, in that incorrect connection could weaken the permanent magnet. Some horn speakers have a solid wire and a striped one; in some the wires are identical; in some the leads are missing.
: Another horn speaker question relates to a posting i saw on this forum last year, suggesting that horn speakers be connected to the radio's output via a choke and capacitor arrangement, rather than directly The idea was to avoid high DC voltage in the speaker coil. How necessary or practical is that? If indeed useful, how would one go about making such a setup, and how bulky would the choke have to be?
: Any advice would be appreciated. These two issues make me nervous about using my horn speakers, for fear of frying them in one way or another.
: Thanks
: Lode Swinnen