[davidgrace]

I recently purchased a barely used warrantied Audi by Van Alstine CF RB preamplifier with the Vision Adjustable Phono Circuit.
So far I've very pleased. The headphone amplifier is a major improvement over my previous AVA PAS 4i and my-new to me- Harbeth 30.1 are glad to show more and more detail revealed as their is more extension at the high and low end.
I'm not sure if they replaced the tubes before selling it to me so I'm not sure if these are broken in but the mid range seems somewhat recessed.
I'm suggestions on which tubes people use.
Also, I find with the CF RB and my PS Audio HCA-2 driving my Harbeths I'm only at about 7 o'clock on the volume setting at normal listening levels. Would I get better sound quality at a more central position on the volume control? Is their simple way internally to lower the gain?
Thanks.
David 

[tjhendry]

Hi, David.

Those Harbeths shouldn't be delivering recessed mids!

Start with the 12AT7s.  I think you would be happiest with British valves.  I like Brimars.

Check out this site.
https://www.tubemonger.com/12AT7_ECC81_E81CC_ECC801S_6201_6060_CV455_CV4024_CV4033_13D_s/8.htm

Contact them for recommendations.  The CV4033 comes in different vintages....one of them might be the winner.

Good luck.
Enjoy!

Tom

[avahifi]

We can lower the gain by changing a couple of resistor values but will need to see the unit to do this.

No charge except for shipping.

Frank

[davidgrace]

Will there be any improvement in sound quality Frank or is it really not an issue?
It sounds very good with some fine tuning involved in terms of my system and the volume control is clearly far superior to the one in my previous preamp.
Thanks.
David