hi everyone.
instead of using a fixed high gain electronic module (whatever the technology) and an attenuation pot (whatever the technology) , why not have a preamp circuit that exhibits from the start the exact gain needed according to the source output level, amp sensitivity and listening level chosen ?
For instance, with today's sources and amps and at usual listening level, you often need a say 0dB gain preamp so your common and possibly very expensive 20dB line preamp has -20db of attenuation in front or in tail. Not the shortest road ... As we say in French : "Quand le tabouret est trop bas, on coupe les pieds du piano". By the way, most line preamp designs have in reality an enormous gain that is reduced to around 10 by the use of negative feedback.
Here is a three BJT tunable gain preamp -very messy- prototype that gives 20dB of max gain, very large bandwidth and very decent output impedance. No feedback used, no regulated PSU but cross wired double choke on balanced bipolar PS and by design very low power power trans instead (definitely not the modern trend !), among other things.
Considering the very encouraging sonic results, I believe the idea is worth digging.
instead of using a fixed high gain electronic module (whatever the technology) and an attenuation pot (whatever the technology) , why not have a preamp circuit that exhibits from the start the exact gain needed according to the source output level, amp sensitivity and listening level chosen ?
For instance, with today's sources and amps and at usual listening level, you often need a say 0dB gain preamp so your common and possibly very expensive 20dB line preamp has -20db of attenuation in front or in tail. Not the shortest road ... As we say in French : "Quand le tabouret est trop bas, on coupe les pieds du piano". By the way, most line preamp designs have in reality an enormous gain that is reduced to around 10 by the use of negative feedback.
Here is a three BJT tunable gain preamp -very messy- prototype that gives 20dB of max gain, very large bandwidth and very decent output impedance. No feedback used, no regulated PSU but cross wired double choke on balanced bipolar PS and by design very low power power trans instead (definitely not the modern trend !), among other things.
Considering the very encouraging sonic results, I believe the idea is worth digging.
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And what happens if environment noise increases? (Neighbour is at party, a powerful street machine as example)
You just increase the gain exactly as in a conventional preamp, for it is variable ( provided you want to keep on listening to your favourite music with a party going on next door).
Seen from the user, there's no difference between conventional and gain adjustable preamps.
Seen from the user, there's no difference between conventional and gain adjustable preamps.
The root problem is another: why on Earth does people add absolutely unneeded "do nothing" Line amps/preamps between perfectly matched signal sources and amplifiers is way beyond me.
Maybe you should take a page from the "passive preamp" guys and build a box with directly connected input and output jacks and label it: "low distortion wide bandwidth unity gain Line Amp"
You can take it a step further as I did.
Flat from CD
EQ and match FM to CD
Match AM to CD
Match Iphone to CD
Match Phono to CD
Some SQ added too.
Tape monitors flat.
Tube preamp SS amp
Flat from CD
EQ and match FM to CD
Match AM to CD
Match Iphone to CD
Match Phono to CD
Some SQ added too.
Tape monitors flat.
Tube preamp SS amp
Sorry, i don't share your view about supposed 'do nothing' devices.Perhaps you should widen your mind and experience about audio gear.