I am starting to really like the buffer with the ccs in it's tail. Bass gains in definition and there is an overall increase in speed and attack... This requires much care in setting the correct riaa curve because it can "show" any flaws that where hidden by the buffer with large Rs arrangement.... I believe this resistor acts as a local feedback that tends to mask things a bit.
I wonder if we could have even more gains by fixing the drain operation voltage with an active boostrad over the common source.....
I wonder if we could have even more gains by fixing the drain operation voltage with an active boostrad over the common source.....
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Ok. That is what i have. Thanks. I like your idea and Allen has a bit of a reputation with that particular preamp. I listened again yesterday with brothers ortofon bronze. It is simply wonderful. I am sure there are others that are as good, but at this point it would seem we are just talking flavor rather than quality.
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SIO.
My brother will not let me play the cap game with his RIAA, so I will have to do it with my version. When we changed from the original Obbligato to the SIO, I knew this was an excellent pre. THe reason being, the cap largely defined the sound. I cannot emphasize this enough. If you want to "hear" a cap, this is the design for it. I wish i had a lot of cap experience, because if i had a favorite, it would be found in both coupling cap positions. Rush has used a DCB1 as the output buffer, allowing for small but high qulaity interstage. This may be the ideal scenario, but i do like the simplicity of teh current setup. If someone told me the copper VCap would improve sound, I would have no qualms buying it.
My brother will not let me play the cap game with his RIAA, so I will have to do it with my version. When we changed from the original Obbligato to the SIO, I knew this was an excellent pre. THe reason being, the cap largely defined the sound. I cannot emphasize this enough. If you want to "hear" a cap, this is the design for it. I wish i had a lot of cap experience, because if i had a favorite, it would be found in both coupling cap positions. Rush has used a DCB1 as the output buffer, allowing for small but high qulaity interstage. This may be the ideal scenario, but i do like the simplicity of teh current setup. If someone told me the copper VCap would improve sound, I would have no qualms buying it.
Perfect.. this info corroborates my last fet measurements.
Must update the simplistic calculator
Beware.... I played a lot with cap types in the riaa filter circuit and in the beguinning I believed the differences I heard where due to cap type... I have built many and now I know the cap value is determinant... not cap dielectric or electrode material.
For instance, switching from 15.15nF to 15.6nF totally kills the magic... the same with the 47n that should not be replaced by 46,5 or 48n....