Hi,
I'm thinking about a tube preamp. It has to be balanced, use the least amount of tubes and use solid state to support the tubes. I opted for 6SN7 in differential pair loaded with CCS. Second stage is a buffer with an emitter follower, loaded with CCS too.
Split CCS for diff pair should help hold both tubes in reins when they mature. Outpu buffer is good with 10k//10nF at around 3Vrms. Any feedback is appreciated!
I'm thinking about a tube preamp. It has to be balanced, use the least amount of tubes and use solid state to support the tubes. I opted for 6SN7 in differential pair loaded with CCS. Second stage is a buffer with an emitter follower, loaded with CCS too.
Split CCS for diff pair should help hold both tubes in reins when they mature. Outpu buffer is good with 10k//10nF at around 3Vrms. Any feedback is appreciated!
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Unique, anyway.
My Dad never owned a preamp. AM radio, then later he advanced, a vacuum tube FM table radio. He thought the wood case was what made them sound good. Still have both the radios.
I own a preamp, but the PAS2 kit was built when I was 11. Bought it used in 1970. Always was a classic.
My Dad never owned a preamp. AM radio, then later he advanced, a vacuum tube FM table radio. He thought the wood case was what made them sound good. Still have both the radios.
I own a preamp, but the PAS2 kit was built when I was 11. Bought it used in 1970. Always was a classic.
How was anyone supposed to know it was line level. Line level doesn't need a pre amp.
There are hundreds of known good designs on the internet that would be useful as a base and modified to make you think it is your own design.
Without gain the noise level will increase.
If the -Vg of the diff pair are not equal there is a current trough the R7 making the currents in the pair different.
Better one CCS and a trimpot to balance the voltages on the anodes = equal current.
Finaly, i like sipmlifying
Mona
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@indianajo that looks like a great kit, shame those weren't avaiable in Europe.
The title "Not your dads preamp" is about using solid state in aid of the tubes, because well, then there weren't too much transistors
@JonSnellElectronic
You're right, this topic should land in Line Level section of forum, my bad. Hopefully mods can move it.
I know, there is a lot of good proven tube topologies from common cathode - common anode, through mu-follower, SRPP and others. Right now I use Aikido with 12AU7 and 6922. My idea is to use tubes as the main active element that amplifies and influences the sound, when solid state devices are used to help it. Since good NOS tubes are getting more and more expensive, harder to get matched pairs I want my design to use the least amount of them and keep them alive for as long as possible. Thats what transistors do here.
@Ketje that was the first design actually. Both circuits are interchangable. Yes, the resistor reduces the amount of mismatch that the circuit will correct, but I think that increasing it to 1k can give reasonable option for correction. Especially that I don't care for gain since it is line level (DAC and phono, so I need some gain, but thats it). I'll be trying both in the actual prototype.
The title "Not your dads preamp" is about using solid state in aid of the tubes, because well, then there weren't too much transistors
@JonSnellElectronic
You're right, this topic should land in Line Level section of forum, my bad. Hopefully mods can move it.
I know, there is a lot of good proven tube topologies from common cathode - common anode, through mu-follower, SRPP and others. Right now I use Aikido with 12AU7 and 6922. My idea is to use tubes as the main active element that amplifies and influences the sound, when solid state devices are used to help it. Since good NOS tubes are getting more and more expensive, harder to get matched pairs I want my design to use the least amount of them and keep them alive for as long as possible. Thats what transistors do here.
@Ketje that was the first design actually. Both circuits are interchangable. Yes, the resistor reduces the amount of mismatch that the circuit will correct, but I think that increasing it to 1k can give reasonable option for correction. Especially that I don't care for gain since it is line level (DAC and phono, so I need some gain, but thats it). I'll be trying both in the actual prototype.
Small update
It's been a long time!
I changed the tube to contemporary and cheap ECC99 (recommended by a knowlegable friend). Buffer is using MOSFET as it greatly reduced distortion in sim. Each buffer has it's own voltage reference for nicer, cleaner layout. See attached:
It's been a long time!
I changed the tube to contemporary and cheap ECC99 (recommended by a knowlegable friend). Buffer is using MOSFET as it greatly reduced distortion in sim. Each buffer has it's own voltage reference for nicer, cleaner layout. See attached:
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