Question About Audio Research Preamp Specs

Well now.

I like the sound of the CJ pre except for the slight LF rolloff due to the impedance issue.

Maybe I should call CJ and ask them if they can adjust the caps on the 17LS2. 

Or look into the ET5 which has a lower out impedance. 

Thanks for listening,

Dsper

Maybe I should call CJ and ask them if they can adjust the caps on the 17LS2.

Great idea, tell them you want the "uF" of coupling cap increased so you can have "little or no" rolloff above 20hz into your amps 10kohm input impedance.
This is around $20 for the caps, and a 1hr labour.

My calculation for 17ls2’s new coupling caps into the 10kohm of the amp. Any/All are fine.
4.7uf will be -3db at 3hz
6.8uf will be -3db at 2.3hz
10uf will be -3db at 1.6hz

Cheers George

Take that with a grain of salt. I do prefer direct coupling (no cap), best cap is no cap mentality.

But dsper OP one of the best tube preamps hailed even by many tube and solid state preamp manufactures as being the best tube preamp ever made is the Aesthetix Calypso preamp, and it has massive output coupling caps, as shown in this pic circled in red.
https://ibb.co/4Jb0bSV

This is why we direct couple... this limitation is eliminated.
In the photo of the Aesthetix its not clear what the actual value of the coupling capacitors is. But obviously the Aesthetix faces the same issue of what is the lowest impedance it can actually drive actually; this information does not show up in their specs or operating manual. 

georgehifi,

"Great idea, tell them you want the "uF" of coupling cap increased so you can have "little or no" rolloff above 20hz into your amps 10kohm input impedance."

georgehifi, You certainly have given me some discussion points with CJ and what is possible to accomplish. Thank you!

Why would CJ not have done this in the first place? Maybe a cost/benefits decision considering how relatively few amps have 10K ohm impedance?

Or could this possibly change/degrade the overall sound of the preamp?

I assume my last question may illustrate how little I know about this technical stuff so any additional comments would be greatly appreciated!

Thanks for listening,

Dsper

Atmosphere,

" But obviously the Aesthetix faces the same issue of what is the lowest impedance it can actually drive actually; this information does not show up in their specs or operating manual."

I do not understand technically why a particular preamp may have a greater capability to drive a low impedance amplifier.

While, I try to follow these types of discussions, something basic is lacking in my current understanding as well as how it impacts how it sounds..

Could you perhaps elaborate further or direct me to another thread where I am sure that this has been covered before?

Thanks for listening!

Dsper