Check out Mullard's preamp section:
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I think you meant C1, R1... By funky, you meant classic, right?
"A CR network (C1, R1) shunting the anode load produces an advance in phase which increases the stability of the amplifier at high frequencies."
More here >> Mullard 5-10
I was referring to the schematic linked on my second post - it turns out it's different from the earlier schematic I posted, sorry about that... Same idea though, R1 & C1 refer to this Mullard schematic:
An externally hosted image should be here but it was not working when we last tested it.
Jaz
I can't think of any situation where the gain of a ef86 in a preamp would be anything but a disadvantage. It then requires copious amounts of negative feedback to kill the gain - and a preamp is definiately one of those situations where there is little need for feedback.
This tube has no other place than a phono preamp in my opinion.
Shoog
This tube has no other place than a phono preamp in my opinion.
Shoog
I would look into the quite interesting radford ( a vondeful amp by the way )
There is some papers for taming the high gain somewhere ( cant locate it right now ) and a great 2 vol article by Radford explaining the way it works.
An externally hosted image should be here but it was not working when we last tested it.
There is some papers for taming the high gain somewhere ( cant locate it right now ) and a great 2 vol article by Radford explaining the way it works.
I would agree (or a Mic or tapehead preamp) and even then It will be noisier than a decent ECC83 stage.
Why not strap it as a triode to reduce the gain?
The OP was asking about preamps, so why post circuits for power amps?
The network at the anode of the EF86 is to stop feedback loop instability (typically in the low ultrasonic region); the input stage itself is very unlikely to suffer from RF instability.
The EF86 has no place in a modern line stage, as it has far too much gain. Keep a few as spares (for your phono preamp?) and sell the rest so you can buy more suitable valves.
The network at the anode of the EF86 is to stop feedback loop instability (typically in the low ultrasonic region); the input stage itself is very unlikely to suffer from RF instability.
The EF86 has no place in a modern line stage, as it has far too much gain. Keep a few as spares (for your phono preamp?) and sell the rest so you can buy more suitable valves.
Try this, it is really good.
6th Street Bridge: Triode Connected EF86 linestage and headphone amplifier
6th Street Bridge: Triode Connected EF86 linestage and headphone amplifier
It is possible to achieve vanishingly small distortion in a preamp stage without any negative feedback - so why would you use it.
Any of the more appropriate line amp tubes such as the ECC99 or 5687 can deliver orders of magnitude more current drive which will address far more problems than using a weedy EF86.
Shoog
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