View Single Post
Old 26th Oct 2021, 12:08 am   #15
sandy_r
Triode
 
Join Date: Oct 2021
Location: Bournemouth, Dorset, UK.
Posts: 28
Default Re: Celestion PPM Soundex Speaker Impedances

Quote:
Originally Posted by PJL View Post
Is the Low direct to the speaker?
the bakelite panel holding the 3 screw terminal-posts appears to show raised 'links' for the connection variants:

High: use the 2 outer connections
Low: use left and mid connections
Medium: use mid and right connections

the Celestion PPM 19 transformer allows matching to 4 levels of o/p valve and it does this using 3 screw terminal-posts and a wander-plug with 2 sockets (Red and Blue) to provide the necssary combinations (see photo)

the 3 terminals are identified as L, H and C - presumably for Low, High and Common, given that C appears in each connection pair (the column with the wander plug info can just be seen on the far right as Red, Blue, Red, Blue)

this may give Simon some clue as to the intended functionality of his soundex speaker - it might be worth delving inside the case and following the wiring. Interestingly, Simon hasn't mentioned having to provide separate field energisation to his extension speaker (which he reports as sounding "remarkably good")

some extension speakers also include a switch in series with one of the speaker connections, presumably to allow the extension speaker to be switched out of circuit with the radio's AF stage without disturbing the connection to the radio
Attached Thumbnails
Click image for larger version

Name:	Celestion_PPM_19.jpg
Views:	34
Size:	62.7 KB
ID:	244262  

Last edited by sandy_r; 26th Oct 2021 at 12:24 am. Reason: addendum
sandy_r is offline