Its been awhile since I roll or refresh my paramount and Foreplay 1 tubes
Noticed a little tizzy sound plus inreased low frquency hum
Changed my Valvo out on FP1 ecc 82 with Telefunken and the tizzy sound went away and the low hum was noticeably reduced. Did not like the tele edge and swap a pair of phillips. Sound was better tizz gone and so did hum- still there but low level...I mean way down. Really learned the importance of the foreplay tube and how it makes the hum or not
Proceeded to remove my Paramount drivers and
W H O A they were CV4024 !!! but.... but... arn't they suppose to be 5670 0r 12AT7 or CV4013
?
Well I have 4 Ratheon 5670 red labels NOS put them in
Bam !!! loud Hum I mean loud audible any where in the room
So what is happening ? I must have bought CV4013 but got instead the CV 4024 and plugged them in. The pair with TJ 300B perf plates. I have been having these in for over a year and it seem to work fine...but shouldn't the 5670 ( I do not have any cv4013 currently) be just as quite? I mean I have lived with low lew noses - like tube breathing low db 60 hz slight tizzy but this is a loud hum.
If it is so quite with the 4024 is it ok to leave them alone will it hurt something in the Paramount?
Maybe I am not optimizing the circuit with the 4024 in place of the 5670...
I have looked at TDSL for 40024, 40013 and 5670 other than 9 pin and requiring 6.3 v for the filament - the rest seem over my head
Input much appreciated, Thanks in advance
FP 1,2,3, Seduction, 45, Paramount 300B, Paraglow2A3; Dehavilland 845, Eico pp 805,Adcom 555 mono, Sota star saphire ugraded Nova motor & bearings, Et 2.5 carbon wand on Shelter 901, Koetsu rosewood Sig., on magnesium wand, grado sumiko etc. Custom Edgarhorn with Seismic sub
