I can't speak for BAT's phono stage, but many amps and preamps which have need for high quality - low noise tubes and ordinary tubes in the same circuit. All you have to do is ID which are which. I do this in an ARC Pre amp and two Sonic Frontiers amps - saves a lot of money.
Newbee (System | Reviews | Threads | Answers | This Thread)
I think as long as you keep at least matched pairs there is no problem,even different tube types.I think it is very common to buy in matched pairs or quads.You may want to try all Amperex's with a couple Mullards in the right spot for a bit added warmth for instance.In my BAT pre I run 2-7308 AmperexPQ' and 2 Mullards for a bit more warm analog sound.4 Mullards too much[high's rolled off a bit].Mixing various Amperex's[6922 7308 PQ's or not] makes very little differences or none in sound in my BAT.I have fun experimenting[fine Tuning] with Tube rolling in my BAT and CDP.All use 6dj8 family of Tubes.Have fun!JD
Jdlepera (System | Threads | Answers | This Thread)
In most preamps, where the tubes are not working in paralleled push-pull pairs, you shouldn't need to match all the tubes as you might in a power amp. You might, however, want to use matched pairs for each L/R corresponding tube position, to maintain even channel-balance characteristics. However, I don't know if this description applies to your particular model. As far as that question goes, and also which tube positions are critical for acquiring ultra-low-noise tubes, I'd consult with the manufacturer.
Zaikesman (Reviews | Threads | Answers | This Thread)
Thanks for the feedback. I've ordered 4 Amperex 7308 PQ's (matched quad), 2 Amperex 7308 USN's and 2 Mullard E88CC's (matched pairs). I will try them in different spots and let you know how I make out. I'm thinking I should split them like this: 2 Amperex PQ's, 1 Amperex USN, 1 Mullard per channel. Placing them in the same location, but opposite channel. Does this sound correct? Or does it not matter how they are split up?
Jmcgrogan2 (Reviews | Threads | Answers | This Thread)
Yes, I have mixed and matched pairs, but I like to stick to same brands as much as I can. I make sure that the triode sides of my tubes (12ax7s and 6dj8s) are as closely matched as I can get and construction similarities (same batches if you can). I hear differences between Mullards, Telefunkens, Amperex, GEs...list goes on. See if you google an ariticle that apeared on Welborne Labs catalog from years back when they interview the person from RAM Labs -interesting topic about which are better tubes and what matters most. Sometimes my Mullards are smoother sounding in the midrange and my Teles are more detailed...etc. My preamp -ARC SP-6 has a procedure for biasing the tubes (requires ocilliscope).
One_audiophile (Threads | Answers | This Thread)