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6P15

Sensibly equivalent to:
6BQ5 CV2975 EL84 N709
See also:
A Small High Quality Amplifier - The Stereoplex Amplifier
    
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The 6P15 is the Type designation for Mazda's version of the EL84 audio output pentode.
When used as a pair in an ultra-linear push-pull configuration with 43% distributed loading the output could reach 10 W with 0.9 % total harmonic distortion.
With ultra-linear operation the screen grids were connected to taps in the in the output transformer primary winding. The valve operating conditions so produced were intermediate between a triode and a pentode. The operation of the distributed loading was to introduce negative feedback directly within the output stage.
This exhibit dates to 1961 and has been taken from a working Murphy radiogram type A674SR that uses Simplex Stereo amplification.
Using the μ-Tracer the above curves were produced. Even after 50+ years it was still at 90% of the nominal design values.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 67 mm tall.
References: Datasheet, 3002 & 1040. Type 6P15 was first introduced in 1958.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
ic
g1
k,g3
h
h
ic
a
ic
g2

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
Pdiss
6.3
0.76
250
250
-7.3
48
5.5
6.7
2.2
12W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated October 28, 2015.
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