hello everybody.
I read in the building article of the VTV line stage it can be use with solid state amplifier but not all. I use a Bryston 10B crossover in my active set-up who have a input impedance of 20k and i have a nice collection of 6SN7 and a pair of Duelund .47uf caps.
I want to use my supply of 6SN7 this is why i prefer a two 6SN7 line stage instead of a 4 one.
It will work correctly with this preamp?
Thanks and regards.
I read in the building article of the VTV line stage it can be use with solid state amplifier but not all. I use a Bryston 10B crossover in my active set-up who have a input impedance of 20k and i have a nice collection of 6SN7 and a pair of Duelund .47uf caps.
I want to use my supply of 6SN7 this is why i prefer a two 6SN7 line stage instead of a 4 one.
It will work correctly with this preamp?
Thanks and regards.
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The 6SN7 cathode follower can drive a 20K load but you should use a larger value coupling cap than .47uf for flat response in the bass.
That was my first impression. At this point any suggestion for a very good DIY preamp using two 6SN7 who can drive a device of 20K input impedance.
Regards.
Regards.
Keep in mind that the time constant of 0.47uF and 1 Meg is 0.47 seconds;
5 time constants is 4.7 seconds.
As the 6SN7 cathode follower warms up, and the 0.47uF cap charges to final voltage, it may put a large voltage at the output connector.
Measure that voltage versus warmup time, before you connect it to a solid state amplifier input.
Your Mileage May Vary.
5 time constants is 4.7 seconds.
As the 6SN7 cathode follower warms up, and the 0.47uF cap charges to final voltage, it may put a large voltage at the output connector.
Measure that voltage versus warmup time, before you connect it to a solid state amplifier input.
Your Mileage May Vary.
Apart from a couple of reliability issues this stage has a gain of approx. 17
Do you really need it?
Do you really need it?
Good question, my amps are a pair of single ended 6v6 Lacewood amps who are rated at 4 watts who drive two way speakers via the active crossover. My actual line preamp is the 4s preamplifier with cathode follower who i don't know the gain. I am very satisfied with the performance but i am willing to try a 6SN7 based preamp.
Regards.
Regards.
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A high voltage delay that then comes on suddenly will actually cause an extremely large transient at the output.
Perhaps a very long soft start filament will bring the cathode follower up slow enough to reduce the transient.
That is hard to do, because the warmup of the filament/cathodes is logarithmic.
Some people use zener diode / steering diode pairs at the output to limit the transient.
The steering diode is in series with the zener, to reduce the capacitive load on the output.
Perhaps a very long soft start filament will bring the cathode follower up slow enough to reduce the transient.
That is hard to do, because the warmup of the filament/cathodes is logarithmic.
Some people use zener diode / steering diode pairs at the output to limit the transient.
The steering diode is in series with the zener, to reduce the capacitive load on the output.
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