But the audio output tube(s) determine the optimum impedance that the plate(s) want to see. (But it's not all that critical.) (I put the plural in parens because I don't know whether the set has push-pull or single-ended audio output.)
Look up the tube data for your output tubes, and it should tell you the prefered load (speaker impedance). Then pick a speaker and output xfmr that gives you that impedance (more or less).
Speaker imp x (xfmr turns ratio)^2 = load imp
Doug
:Hello!
:I recently aquired a Aria 175 and is the same the above mentioned radio. My problem is the original speaker is missing and I need a replacement speaker. I know the original was a 8 inch Rola with a transformer. I have found several speakers on the web but I have no way of knowing what the speaker and tranformer's values are since their not noted in the schematic. Does anyone know how to figure out what those might be? This would be such a great radio with the motorized tuning, but it might sound evn better with the proper speaker. Any help would be greatly appreciated. Thanks!
:Kevin
Get a "univeral" center-tapped xfmr, along with a modern, say 8-ohm speaker, and play around with it.
Doug
::Kevin, can you link us to a schematic for this set?
::
::But the audio output tube(s) determine the optimum impedance that the plate(s) want to see. (But it's not all that critical.) (I put the plural in parens because I don't know whether the set has push-pull or single-ended audio output.)
::
::Look up the tube data for your output tubes, and it should tell you the prefered load (speaker impedance). Then pick a speaker and output xfmr that gives you that impedance (more or less).
::
::Speaker imp x (xfmr turns ratio)^2 = load imp
::Doug
::
:::Hello!
:::I recently aquired a Aria 175 and is the same the above mentioned radio. My problem is the original speaker is missing and I need a replacement speaker. I know the original was a 8 inch Rola with a transformer. I have found several speakers on the web but I have no way of knowing what the speaker and tranformer's values are since their not noted in the schematic. Does anyone know how to figure out what those might be? This would be such a great radio with the motorized tuning, but it might sound evn better with the proper speaker. Any help would be greatly appreciated. Thanks!
:::Kevin
:Hi Doug!
:According to the schematic(same as Detrola 175, Truetone D-727) the radio uses 2 each 42's for the output which I assume the audio output is push-pull. The tube line-up is as follows- 6A7,6D7,75,76,42,42,80, and a 6G5. I'm not quite clear about your formula, but I'll try to figure it out. Thanks Doug for sending me in the right direction. Oh by the way, the guy I purchased the radio from(which I haven't received yet) seems to think he still has the speaker somewhere but can't seem to locate it....darn!Again thank you Doug!
:42 = 6G6, electronicaly.
:
:Get a "univeral" center-tapped xfmr, along with a modern, say 8-ohm speaker, and play around with it.
:Doug
:
:
:
:::Kevin, can you link us to a schematic for this set?
:::
:::But the audio output tube(s) determine the optimum impedance that the plate(s) want to see. (But it's not all that critical.) (I put the plural in parens because I don't know whether the set has push-pull or single-ended audio output.)
:::
:::Look up the tube data for your output tubes, and it should tell you the prefered load (speaker impedance). Then pick a speaker and output xfmr that gives you that impedance (more or less).
:::
:::Speaker imp x (xfmr turns ratio)^2 = load imp
:::Doug
:::
::::Hello!
::::I recently aquired a Aria 175 and is the same the above mentioned radio. My problem is the original speaker is missing and I need a replacement speaker. I know the original was a 8 inch Rola with a transformer. I have found several speakers on the web but I have no way of knowing what the speaker and tranformer's values are since their not noted in the schematic. Does anyone know how to figure out what those might be? This would be such a great radio with the motorized tuning, but it might sound evn better with the proper speaker. Any help would be greatly appreciated. Thanks!
::::Kevin
::Hi Doug!
::According to the schematic(same as Detrola 175, Truetone D-727) the radio uses 2 each 42's for the output which I assume the audio output is push-pull. The tube line-up is as follows- 6A7,6D7,75,76,42,42,80, and a 6G5. I'm not quite clear about your formula, but I'll try to figure it out. Thanks Doug for sending me in the right direction. Oh by the way, the guy I purchased the radio from(which I haven't received yet) seems to think he still has the speaker somewhere but can't seem to locate it....darn!Again thank you Doug!
Google a place called "Bill's Antique Radio" this guy has a whole bunch of stuff, including what impedance to use for output transformers for diffeerent tubes.
Also, a lot of other good stuff.
Lewis