Reply 27 by Joman: "Will suggested Tungsram 5V4G's" Just a heads up. I have not tried Tunsgram 5V4Gs.
But I would have recommended trying an early Tungsol 5V4 GA fat/straight bottle with a bottom D getter as a Mullard alternative. These may actually be RCA made??? They have a very similar plate/getter setup as the RCA 5V4G ST (coke bottle) black plates I have, though the plates look greyer in the GAs. The Tungsol looks very close to the RCA GA (fat bottle) I just found
http://www.ebay.com/itm/RCA-5V4GA-NOS-NIB-1967-Vacuum-Tube-/322441197287?hash=it... I have also seen a Raytheon labelled tube that looks just like this RCA and the Tungsol I have.
These impressions are using the tubes in the CSP3.
The fat bottle has a pretty different sound to me than the RCA 5V4G-ST I have, the ST balancing open, though more dark/soft/ mids up, with bigger/warmer feeling overall, the mids down bigger in the balance, and slower feeling.
Alternately, the Tungsol 5V4 GA (fat/straight bottle) with a bottom D getter is more neutral to me, closer to the Mullard GZ32 I have than most 5V4G types. I would say this Tungsol fat bottle has more midrange inner detail and air than the Mullard, and may be a little faster/punchier. It and the Mullard have more fine detail, speed and space than the RCA ST. Both the Tungsol and Mullard have more complexity of detail, more fine detail, things I really like for revealing timbre...textures, space, and ambient information.
The Tungsol has a little rounder bottom than the Mullard, but is not as warm/big/round lower down as the RCA ST. I would probably put the Mullard's sense of overall "warmth" in between the two and more even top to bottom. Depending what it is with, the RCA ST can go so far as to tend to loose on bottom. But it can be pretty tight, just depends on the rest.
I really like the faster, more complex Tungsol fat bottle and Mullard here, and have never adapted to the RCA ST in my setup. The RCA ST is good tube, showing very refined qualities, but for me, in this setting, it is a little too colored, dark, and rigid. I can imagine that these could be very good traits in some settings though!
Anyway, Mark, from what I can tell "RCA 5V4G" is more than one tube, different shapes and vintages having different sounds. I have consistently found that with straight bottles, fat bottles, and coke bottle shapes, the shape influences the sound. So I think this is a relevant distinction when discussing tubes. Everything matters...mica type and placement, plates, getters, all of it.
I am sure I have posted this in other tube threads, but as a Mullard alternative, the Mazda labelled Phillips GZ32 ST shape, with double bottom D getters (one on each side) I have are really good too. They are just a little cleaner than the late 50s Mullard, but quite similar in terms of linearity, speed, and the Phillips way of conveying clarity and detail with warmth so well integrated it sounds like the warmth is part of the detail. With many tubes, the darkness associated with "warmth" is there "along with" the detail, having sort of a separate sound that masks detail rather than sounding integrated with it if that makes any sense.
The Mazdas and Mullard GZ32 STs I have have flawlessly integrate warmth, softening/warming things without loss of detail or space.
Another really good, less expensive alternative to the Mullards was an early Adzam/Phillips I had, but it shorted. It was a really nice sounding tube, every bit as sophisticated as the Mullard. I can't say what vintage is was, but its construction was just like the late 50s Mullard I have.
So Mark, based on your preference for hot topped RTF EL34s and how American Amperex 7308s tone that down a little while still appearing open and textured, the toned down RCA 5V4 STs
might be your best bet. Which ones are in the Monos?
The old Mullard GZ32 might work too though. Similarly to the RTFs, they do "clear" with an interesting textured "warmth" mixed into the clarity, but more clear/complex/linear/fast than the RCA 5V4G-ST I have, so may be a little risky there??? Or maybe not!