Rectifier tubes?

I have bought two recs which were highly recommended by my amp's importer as being far superior to that which came with amp. I shopped around (at 3 different sources) and located two of the highly prized NOS - thus the high price. I have to say that both tubes sound the same and I can't tell a difference, except between the one which came standard and a $20.00 new one. That is to say, the NOS tubes sound superb and have improved the musical performance of my Air Tight in a very meaningful way. Have to say I don't fully understand why a change in retifier tubes would make such a difference but it does. I just need to find someone who can test my existing tubes as I think one of them is slowly dying.

Hi Tonryan. Chriskeating's post above is an appropriate one regarding ramp up time. Does the airtight have a standby switch? Indirectly heated rectifiers vary in ramp up time in comparison to directly heated rectifiers. This lag time will prevent cathode stripping of the other tubes in your amp. Regarding sound of rectifiers.... While it may be difficult for some people to comprehend,like input tubes,driver tubes,and output tubes... rectifiers do make a difference and can have a major influence on the sound of the amplifier or preamplifier. If the amp or preamp employs a vacuum tube for rectification... it should be the first logical place to start regarding tube rolling for voicing ones system, as they can [and do] have a major influence. One can invest in expensive nos tubes for the input or outputs and only hear minimal changes in tonal balance,bass drive, frequency extention etc when a weak, unbalanced or mediocre rectifier is employed in the circuit,and then wonder what all the fuss is about with nos tubes! Swap out the sovtek or weak rectifier for a strong nos one and be prepared for a whole higher order here[ WOWZA]. The Western Electric 274b..... unlike the majority of Western Electric manufactured tubes, the 274b rectifier is grossly overrated and overpriced, you can find far better for less coin [much less]. The same can be said for a good many of the English rectifiers[mullard excluded here]... like the fabelled U-52. Typically... any early US and Canadian made coke bottle style 5u4g from the 40's will transform your amplifier to a whole higher order as long as both halves are close and the tube test strong. The original Tung-sol coke bottle being my particular favorite of the bunch. The RCA, sylvania, GE and many branded 5u4g coke bottles will simply stomp on any of the current equivalents.

Ecc. - I actually have 5 recs., two new ones (both a bit rough sounding) and three NOS all of which "stomp on" the new new tubes. My favorite of these in order are:

1) Sylvania - 1943
2) RCA - 1955
3) Ken Rad - 1940s

I'm afraid the RCA is nearing it's end, though. It arrived in used condition and was not NOS as advertised. However, it has provided wonderful music for the last 2 years and I don't regret the $85.00 spent.

Unfortunately, the Air Tight does not have a soft start feature so I have a shelf full of input and rectifiers tubes. However, I'm still using the WE 300B output tubes that came with amp three years ago and they spec out fine, at least by my amp's own bias meter.

Hi Tomryan. Forget about changing out your rectifier as both the Sylvania and Kenrad 5u4g's are terrific and should last a long time. While I have never had the pleasure of hearing the Air Tight 300b with the Western Electric tubes in it, after hearing a pair of their 2's. I am most certain it would be something very special indeed.

I may try the Sophia version just for fun but am still using the RCA which sounded just fine last night. I will use it until finding someone for testing and always have the other two for replacements. Why can't new tubes be made like the old ones? Anyone know?