Hi, just wondering out there if anyone has any 6J7G's
of if there is an equivalent

Thanks
Josh

I hope the book I sent you helps.

Found the equivalents manual that I hand-made back in the 70s. It is based on pin connections, base and heater voltage only. There is no check for physical differences, or change in operating characteristics.

So, according to the list, the 6J7 is equivalent to : 6K7, 6S7, 6U7, 6W7, EF36, EF37, EF39, Z66, 1620

There will be differences many are not direct equivalents albeit they will run, and I have found them in the others socket.

6J7, 6W7, EF36, EF37, Z66, 1620 are Sharp cut-off ,

6K7, 6S7, 6U7, EF39, are Remote cut-off

Using Remote cutoff may have undesirable effects & the Philips valves must have pin 1 grounded.

Thanks for pointing that out. The problem with my list is that it was compiled before I knew anything much.

Going over it again, we firstly consider that the 6J7G has a shield, and so pin 1 of the socket will already be grounded. The exact equivalent as far as operating characteristics go is the 1620. The EF36 and EF37 would be the next bet. After that the 6W7 and Z66 could be considered, however as they have no shielding, an external one would need to be fitted.

A remote cut-off valve could next be considered, and since the grid bias would be a fixed voltage, it could be considered as a normal pentode however it might happen to be biased at a lower amplification. The only way is to try it out.

Of those then, the 6K7, 6K7GT, 6S7 and EF39 come with shielding, but the 6K7G, 6S7G and 6U7G do not.

Hopefully this should clear things up a bit.

There is another shield trap worth noting: 6K7 may well be a metal valve but 6K7 in glass 6K7-G will not be shielded, but 6K7-GT will.

Where there is AGC the "attack" may suffer with the wrong valve type.

Thanks all,
2 of the 6J7G's have an external shield and they are straight preamps..
Was considering 6K7G's, earthing pin 1 not a problem,
lower gain also not a huge problem as the unit seems to
have pots stuck between everything to lower the level feeding the amp.
so if all else fails might try 6K7G's as a last resort

Josh

If its being used for an audio amp, or phase splitting, then you will get away with anything but do remember any RF that creeps in they will amplify it (most valves will).

It would be unusual for an amp not to have gain controls, if that is what it is. The mixers (4) on an amp here all have gain control as well as volume control, as it has no automatic feedback control. As we know if the mic is made too sensitive & input starts picking up output & that"s why they howl.

Marc

It does have gain controls on the amp but the Radio and the
Turntable both have pots before the amp gain controls.
one of the switches on the front switches between the radio's
speaker and a reversed speaker transformer which is
what they use to feed the input of the mixer.
I could understand that pot as that setup could overdrive the input BUT
the pot on the turntable tone arm was a bit of a "what the"

Josh