More EF91 reviews! I just got a package filled exclusively with CV4014 of three different brands. This time I took pictures, which makes it a lot easier to understand tube construction and getter shapes (and shop on ebay thereafter).
Mullard CV4014 KB/DC, made in the Whyteleafe factory (so quite rare) in 1959. Blue glass, rectangle D getter above a cage element, metal cage thingies between the anodes around the tube (seen on the left of the picture behind the writings.
These have an extremely large 3D soundstage that sounds like a huge cave (not in a bad way) with the opposite of an "in your face" presentation. Bass is loose and dry (not fat), somewhat piano like with a slow decay. treble is airy and non sibilant, a bit elevated, again the instruments are presented in a very spacious way and very well separated (more like far apart). Mids and vocals are fine, not under-emphasized and musical. You could say these tubes have a fairly u-shaped signature but not overly so. For some reason, they aren't as loud as other EF91s, but closer to the my CV4015 in terms of volume.
Overall, these are great CV4014 tubes (what did you expect?), at least as good as their Mitcham counterparts made in the same time period if not better, and much more spacious. While not quite as detailed as the CV4015 (hard to dethrone), this is a top tier tube, a laid back, balanced and easy to listen to CV4014, great for alternative and casual styles of music.
GEC CV4014 KB/Z, made in 1960 (MO Valve Company in Hammersmith). Square getter on top of a hollow dark grey box, silver all around the glass. I got 8 of these, all identical, but two have an extra "GEC" sticker like on the picture, I tested two others with only the military markings.
Now there's an interesting tube. More weighty and dense than the Mullards, guitars have more impact and fell heavier, vocals are fatter (or less thin than most EF91 tubes). Soundstage is large but feels very natural, like the CV4015. There's a typical emphasis on highs but also on mids, which is unusual for EF91s, no U-shaped sound here, more of a swoosh curve. Mids and mid-bass are really liquid (think tubey but in a good way, not harmonic distortion) and have a nice weight to them. Bass is neutral and tight and you hear it when it's in the music, it's not overdone but punchy and well controlled, closer to an EF92 tube. These tubes are quite resolving without feeling over detailed and too bright; the micro details are presented in a discrete but adequate way (you don't hear really loud brassy sounds a foot away from your head like it's the only instrument there, too much "air" kills the music). The vocals really have a fluidity and naturalness that is unusual for EF91s.
Overall, excellent CV4014, probably one of the best I've heard. Great balance, punchy and meaty "just detailed enough to not be annoying". Great mids for an EF91 and even in general, tight thumpy bass. Only caveat would be that like most EF91/92s, these feel a tad bright, but that's compensated by the liquid midrange!
Brimar CV4014 KB/FB (doesn't say Brimar, but everything goes that direction; previous CV138 KB/FB I'd tested were also Brimar), made in 1957 in STC, Footscray. Folded D getter and silver glass all around, only military markings and 6064 on the tube.
First impression is the great clarity of this tube when played, details stand out in a natural way in an average size soundstage (read large, this is an EF91). Treble isn't overemphasized yet it is quite pleasant and detailed, mids are pretty good and make vocals sound natural but not brilliant. Bass has that special "Brimar" flavor to it, but in a tighter/drier variety than the Brimar CV4014 with no military markings (see two picture below) I'd tried earlier. I happen to quite enjoy that bass, even though I wouldn't want it everyday.
Overall, very enjoyable CV4014, not the most detailed but natural, balanced and resolving, with toe-tapping peculiar bass!
Brimar CV4014 KB/FB, can't quite read the date markings, but they should be from 1959. Same characteristics and factory as above, only difference is the large O getter, the rest of the construction is identical.
These sound almost the same as the folded D getter ones, maybe just a bit tamer, but still balanced, natural and with peculiar bass.
These are the original Brimar CV4014 I'd reviewed, they have the same construction as the two above but with a small O getter. In terms of sound, they are similar but the bass is fatter (not as tight). All Brimar CV4014 tubes are great to try though.
In any case, these 4 pairs of tubes were a cool set of CV4014 to test and give feedback on. But, as usual, I'm sure when I put the CV4015 back in and "recalibrate" my brain and ears, I'll remember why I keep going back to them...
A few more pics of the other tubes I'd reviewed (I'll try and update my previous post too).
These are the later "flashing" Mullard CV4014, I have years '66 '68 & '72, all identical, see the O getter with no cage like element underneath and the open structure between the anodes.
The late 50s Mitcham-made Mullard CV4014 I'd reviewed, see the cage below the D getter and the metal thing between anodes.
The 50's Mullard CV138 I don't like (that sounds spiky like old basic EF91 tubes with the same flying copper leads with a black rectangle suspended on top).
The 50's Mullard CV138 6AM6 that I do like and could live with, with a much more solid construction than the ones I don't like.
And while I'm at it, my Mullard CV4015 that I keep going back to.
Voila, that's it
(Btw, no I'm not trying to impose a subliminal message to buy "Sony" products lol. I just realized I have the logo on all my pictures... Sorry about that ;) )