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Diabolical Artificer · 16th Jun 2019, 9:56 am

A few questions on preamp architecture...
1) Phono amp passive or feedback RIAA filter? I've read passive designs are bad as they have high gain in the first stage which is then chucked away in the RIAA filter.
2) In this amp there will a phono amp and line amp, in the designs so far looked at most have a cathode follower buffer, is it ok for the phono and line amps to share a common KF?
3) Where is the best place for the volume/attenuator to go? After the line stage? Before the KF buffer? Also what value with how much attenuation? So far 100k/60dB are the figures I've arrived at.
4) I have some far out switches that would make good attenuators, is an attenuator better than a standard log pot, if so it it better to have constant Zin or out?

Andy.

16th Jun 2019, 9:56 am	#32
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,662	Re: Valve preamp. A few questions on preamp architecture... 1) Phono amp passive or feedback RIAA filter? I've read passive designs are bad as they have high gain in the first stage which is then chucked away in the RIAA filter. 2) In this amp there will a phono amp and line amp, in the designs so far looked at most have a cathode follower buffer, is it ok for the phono and line amps to share a common KF? 3) Where is the best place for the volume/attenuator to go? After the line stage? Before the KF buffer? Also what value with how much attenuation? So far 100k/60dB are the figures I've arrived at. 4) I have some far out switches that would make good attenuators, is an attenuator better than a standard log pot, if so it it better to have constant Zin or out? Andy. __________________ Curiosity hasn't killed this cat...so far.