Quad 22 EF86 RIAA front end

rayma

Member
2011-04-29 8:37 pm
Does anyone know the expected voltage output from the single EF86 RIAA stage?
I am torn between Quad22 single EF86 and standard Mckintosh C220 ECC83 twin triode.
Wondering which will give the highest yield for a valve front end.

For the Quad 22, it depends on which pickup adaptor is installed, but the nominal midband output spec
was 1.4Vrms, for driving the Quad II amplifier. Both 4mV (51db gain) and 10mV (43dB gain)
input sensitivity adaptors were available.

It seems that the McIntosh phono stage has 40dB midband gain, and 4.5mV phono input sensitivity,
with a nominal 0.45V midband output.
 
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the nominal midband output spec
was 1.4Vrms, for driving the Quad II amplifier
No.

The question was about the EF86 output level, not the whole 22 preamp, and the answer is not 1.4V but 70mV, as seen from the specification of the unity gain Tape Adapter, which also goes through the EF86.

The open-loop gain of the stage is 255, and for two ECC83s it would be 10,000, so draw your own conclusions about distortion after NFB, but remember the low current output if you have to drive an active NFB RIAA network. The 22 manages this in a most ingenious way which doesn't load the EF86 unduly, and whose RIAA accuracy is dead nuts on.

Better late than never ;-)

EJP