My 2 cents are based on tubes used as drivers for input section on an integrated amp driving 6SN7's with output tubes KT88/6550's also used with CAL Alpha instead of 12AX7's
The best one for the CAL Alpha is simply the Tungsram ECC83 (12AX7) 100 Mu tubes.
I have tried mullard blackbourne, RCA 7025 black plates, Sylvanias, Amperex, Telefunken smooth plates (Very nice indeed), and a few new production like EH, SHuguang 12AX7A, also the B's (worse than the A's .. .) EH 12AX7.
The GE black plates and gray plates in both versions 2 mica & 3 micas though they are wonderful all of them the Tungsram for the CAL are simply the best combination of bass definition, mids liquidity and top end purity creamy and lively qualities.
Now for the amp driving the 6SN7's i think it is a matter of tubes you use to combine them with and then the synergy with each tube that comes after the chain. in the case of Sylvania's chrome tops (6SN7 GTB)the Tungsram ECC83 were a little bit too bright (I/m nit picking here by a hair), using RCA gray glass 1940's 6SN7 GT and GTA's then the Sylvanias 5751 (BP 3 Micas) took the cake, now I am using a combination for the 6SN7 of Tung-Sol and Zenith branded GE made black plates long envelope (2 and 2 in mirror matched per channel configuration) on that configuration the GE 5751 3 mica black plates just has no equal.
Note that this is driving a quad of Tung-Sol 6550 gray plates 1965 well matched and bias adjusted to +- 1% or each tube. in triode strap. though Ultralinear sound good for 70's rock and reggae, the Triode modejust does magic on all the other music, jazz, voices, classical, R&B, Blues, etc. etc.
So . .. to me the synergy of the tube with whatever comes after in the circuit, and probably before also is the essence of how the sound of the tube you will prefer, also take into consideration the rest of the circuit and that sometimes the 68 Mu gain from a 5751 may not be enough to drive the rest of the circuit compared to a 12AX7 that has a gain of 100 Mu. you need to check on that also
However be warned these tubes are expensive and hard to get choose wisely.
Enjoy the music;
Gonzalo
The best one for the CAL Alpha is simply the Tungsram ECC83 (12AX7) 100 Mu tubes.
I have tried mullard blackbourne, RCA 7025 black plates, Sylvanias, Amperex, Telefunken smooth plates (Very nice indeed), and a few new production like EH, SHuguang 12AX7A, also the B's (worse than the A's .. .) EH 12AX7.
The GE black plates and gray plates in both versions 2 mica & 3 micas though they are wonderful all of them the Tungsram for the CAL are simply the best combination of bass definition, mids liquidity and top end purity creamy and lively qualities.
Now for the amp driving the 6SN7's i think it is a matter of tubes you use to combine them with and then the synergy with each tube that comes after the chain. in the case of Sylvania's chrome tops (6SN7 GTB)the Tungsram ECC83 were a little bit too bright (I/m nit picking here by a hair), using RCA gray glass 1940's 6SN7 GT and GTA's then the Sylvanias 5751 (BP 3 Micas) took the cake, now I am using a combination for the 6SN7 of Tung-Sol and Zenith branded GE made black plates long envelope (2 and 2 in mirror matched per channel configuration) on that configuration the GE 5751 3 mica black plates just has no equal.
Note that this is driving a quad of Tung-Sol 6550 gray plates 1965 well matched and bias adjusted to +- 1% or each tube. in triode strap. though Ultralinear sound good for 70's rock and reggae, the Triode modejust does magic on all the other music, jazz, voices, classical, R&B, Blues, etc. etc.
So . .. to me the synergy of the tube with whatever comes after in the circuit, and probably before also is the essence of how the sound of the tube you will prefer, also take into consideration the rest of the circuit and that sometimes the 68 Mu gain from a 5751 may not be enough to drive the rest of the circuit compared to a 12AX7 that has a gain of 100 Mu. you need to check on that also
However be warned these tubes are expensive and hard to get choose wisely.
Enjoy the music;
Gonzalo