[RickH]

Does anyone see any fatal flaws, "gotchas" or impossiblilities about
making an adaptor that would allow someone to plug a 6SN7 dual triode
into a 12AX7 dual triode hole? Knowing the specific circuit it is
going to be used in, and assuming it will fit physically?

[Sander deWaal]

"RickH" said:

Does anyone see any fatal flaws, "gotchas" or impossiblilities about
making an adaptor that would allow someone to plug a 6SN7 dual triode
into a 12AX7 dual triode hole? Knowing the specific circuit it is
going to be used in, and assuming it will fit physically?


Is this in a guitar amp?

A better comparison would be a 6SL7 vs. a 12AX7.

The 6SN7 can be swapped for a 12AU7 in most cases, without any circuit
changes.
Swapping a 6SN7 for a 12AX7 may pose problems, wrt. gain and voltage
driving ability.

Then again, some guitar folks like 12AT7s in place of 12AX7s, so
anything goes.

Nothing will be damaged, however.

--

- Maggies are an addiction for life. -

[[email protected]]

On Feb 2, 12:00 pm, "RickH" wrote:
Does anyone see any fatal flaws, "gotchas" or impossiblilities about
making an adaptor that would allow someone to plug a 6SN7 dual triode
into a 12AX7 dual triode hole? Knowing the specific circuit it is
going to be used in, and assuming it will fit physically?

There's a fundamental lack of one-to-one in the filament wiring. It's
two-to-three. Overall the idea might be 12SN7/12SL7 in those cases
where 6SN7/6SL7 doesn't map, with a different adapter.

The octals will be more current-sucking for equivalent plate
resistance etc.

I like the hole terminology better. Maybe I'll label all my sockets as
"tube-holes". And I'll take to calling the place I park the car the
"car-hole" and stop using that fancy French-looking garage word
too :-). Wikipedia tells me that car-hole may be more cromulent
anyway.

Tim.

[RickH]

On Feb 2, 11:15 am, Sander deWaal wrote:
"RickH" said:

Does anyone see any fatal flaws, "gotchas" or impossiblilities about
making an adaptor that would allow someone to plug a 6SN7 dual triode
into a 12AX7 dual triode hole? Knowing the specific circuit it is
going to be used in, and assuming it will fit physically?

Is this in a guitar amp?

A better comparison would be a 6SL7 vs. a 12AX7.

The 6SN7 can be swapped for a 12AU7 in most cases, without any circuit
changes.
Swapping a 6SN7 for a 12AX7 may pose problems, wrt. gain and voltage
driving ability.

Then again, some guitar folks like 12AT7s in place of 12AX7s, so
anything goes.

Nothing will be damaged, however.

--

- Maggies are an addiction for life. -

Thanks, yeah it's a guitar amp

[RickH]

On Feb 2, 11:28 am, wrote:
On Feb 2, 12:00 pm, "RickH" wrote:

Does anyone see any fatal flaws, "gotchas" or impossiblilities about
making an adaptor that would allow someone to plug a 6SN7 dual triode
into a 12AX7 dual triode hole? Knowing the specific circuit it is
going to be used in, and assuming it will fit physically?

There's a fundamental lack of one-to-one in the filament wiring. It's
two-to-three. Overall the idea might be 12SN7/12SL7 in those cases
where 6SN7/6SL7 doesn't map, with a different adapter.

The octals will be more current-sucking for equivalent plate
resistance etc.

I like the hole terminology better. Maybe I'll label all my sockets as
"tube-holes". And I'll take to calling the place I park the car the
"car-hole" and stop using that fancy French-looking garage word
too :-). Wikipedia tells me that car-hole may be more cromulent
anyway.

Tim.

Thanks, dont know why I sail holes instead of sockets. I will look
into the availability of 12v tubes, but I think 6v are in curent
production for SN7 and SL7.

[Sander deWaal]

"RickH" said:


Thanks, dont know why I sail holes instead of sockets. I will look
into the availability of 12v tubes, but I think 6v are in curent
production for SN7 and SL7.


Usually, the power tubes are 6.3V types, so the pre stage tubes are
wired for 6.3 as well.
The ECC81/82/83 or 12AT/AU/AX7 series draw 300 mA when used on 6.3V,
the slightly larger current that 6XX7 types will draw, won't be a
problem.

With the noval ECC 81/82/83 types, pins 4 and 5 are connected together
and wired to one side of the heater winding, pin 9 is connected to the
other.

--

- Maggies are an addiction for life. -

[robert casey]

Mechanically it will be awkward also because you will be putting a
much bigger tube and an adapter on to a 9 pin mini socket, and
mechanical ruggedness-as in roadieworthiness-is everything in guitar
amps. If it'a serious tool, it's probably point wired and has enough
room to go ahead and open the chasssis hole and resocket with a octal.
And if it's a serious working tool ruining its collectability won't
even be a thought.

Unless you happen to have a large supply of 6SN7s, you could just use a
6CG7. That's a 6SN7 in a miniature tube (though the 6CG7 won't take as
much B+ as a 6SN7 can). You'll still have to reconnect the heater pins
though. Otherwise it's a drop in.

[[email protected]]

On Feb 2, 7:21 pm, Sander deWaal wrote:
"RickH" said:

Thanks, dont know why I sail holes instead of sockets. I will look
into the availability of 12v tubes, but I think 6v are in curent
production for SN7 and SL7.

Usually, the power tubes are 6.3V types, so the pre stage tubes are
wired for 6.3 as well.

True, usually.

The ECC81/82/83 or 12AT/AU/AX7 series draw 300 mA when used on 6.3V,
the slightly larger current that 6XX7 types will draw, won't be a
problem.

12AU7 is 300mA at 6.3V, 6SN7 (most obvious octal sub) is 600mA at
6.3V.

If you're only doing this to a single tube out of ten, then the extra
filament current draw will be in the noise. But if you the 12AU7 to
6SN7 swap to the bulk of tubes in a box, you might be pushing past
what the filament transformer can supply.

Nothing against the 6SN7 in general, but I've found that that they
generally have more filament-induced hum than 12AU7's in the same
circuit.

Tim.