10-02-2010, 08:54 PM
Gary,
The 40-180 uses 41 push pull tubes unless you are subbing 42's? If you use 41's the plate load impedance is closer to 12-14K equivalent to the 6K6. If you use 42's it is 10K equivalent to 6F6's.
Don't have experience with the Hammond subs. Sure others are though and can comment. RCA tube manual shows the 6K6 equivalent to the 41 at 12K. The site "www.radioremembered.org" under 'Determining Output Transformer Impedance' shows 14K for the 6K6 in push pull & 10K for 42's. If you go with 10K then Gary at PTOP may have a Philco 32-7981 which is designed for 42's in push pull at $7.75 but with a $20 minimum. The 32-7981 is the exact audio transformer I am currently replacing in my 41-295 which also had an open primary- common problem.
Best of luck, John
The 40-180 uses 41 push pull tubes unless you are subbing 42's? If you use 41's the plate load impedance is closer to 12-14K equivalent to the 6K6. If you use 42's it is 10K equivalent to 6F6's.
Don't have experience with the Hammond subs. Sure others are though and can comment. RCA tube manual shows the 6K6 equivalent to the 41 at 12K. The site "www.radioremembered.org" under 'Determining Output Transformer Impedance' shows 14K for the 6K6 in push pull & 10K for 42's. If you go with 10K then Gary at PTOP may have a Philco 32-7981 which is designed for 42's in push pull at $7.75 but with a $20 minimum. The 32-7981 is the exact audio transformer I am currently replacing in my 41-295 which also had an open primary- common problem.
Best of luck, John
