What do these tubes sound like?

I completely disagree with the assessment of the 300B. “Treble is severely rolled off. As are the lower frequencies, which are the very definition of loose.” The performance of a tube at these frequency extremes is a function of amplifier design and speaker interaction much, much more than the tube. Amps using the 300B can and are designed that give a frequency response well beyond the range of human hearing. I recently sold a Wavelength Duetto 300B SET amp that was -3dB at 15 and 45,000 Hertz. Before that I had a VAC 30/30 that was 8Hz-85,000 Hertz -3dB. If this is a severely rolled off top or bottom end then I don‘t understand what those terms mean.

The loose bottom has more to do with the typical low power of SET amps and poor speaker selection, not the fact that a particular amp is using a 300B. Higher power push-pull 300B amps like the VACs have just as much or more bass control as any other amps of comparable power. If you use a low power SET 300B amp with a low efficiency speaker, you may well have a loose bottom and rolled off highs. Matched to an appropriate speaker they will perform as well or better than any tube out there.

They do have a glorious mid-range.

Herman, you make some good points. I did preface my statements with a line about amplifier circuits and transformers being more critical than the tube itself.

I agree with your statements about the VAC. However, their use of this tube in this manner is definitely in the minority, which is what I meant by not normally using the 300B in a modern amplifier topology. The vast majority of companies use the 300B in an SET amplifier. Kevin Hayes is a genius, and this line of amps of his are the proof.

I also said that the tube is more dependent than most tubes on both the transformers and speakers it is matched with, which you reiterated.

Still, I maintain that the treble and bass are reigned in. That's because in 95+% of the amps in which it is employed, that is what the tube sounds like. Which is the question at hand in this thread. Wavelength and VAC are among the best of tube amps, and Gordon Rankin and Kevin Hayes deserve commendation for their elegant products. How about when Audio Electronic Supply, Antique Sound Labs, Cary, Golden Tube, The Parts Connection(defunct), and the myriad less expensive companies that execute a 300B based amp? Do you think you'll see the same specifications that you listed?

Anyway, I don't really want to get into specifications when it comes to 300B tube amplifiers. Measurements on tube amps, and SET amps in particular do not cast these products in a good light. Normally, their specifications never look as sterling by anyone outside of the designer. Often, they fall apart like a cheap suit when subjected to testing that a horrid sounding mass - fi product aces. Like all amps, what you see through an 8 Ohm dummy load will be far different from what you see when you actually drive anything like a speaker. I don't listen to dummy loads, and I don't know many other audiophiles who do. I listen to music, that's where I base my assertions.

I respect the bass that VAC can produce with the 30/30, but did the Wavelength sound like it could do -3 db at 15 Hz when you listened to it? I have never heard the Duetto, but neither the Cardinal nor the Gemini I did hear would ever make me think about 15 Hz. I really like Wavelength products, but I wouldn't be buying one of their amps based off of the bass that they put out.

Compare the 300B to the 2A3 in the same amplifier circuit, and I maintain that despite the 2A3's decrease in power output, the lower frequencies will be more powerful, more extended, and more tight. I also feel that a similar, but not as pronounced effect will be noticed in the higher frequencies. The 300B will have the edge in what you so rightly stated as a glorious midrange.

I thank you for the provocative and interesting discussion. It's great to talk about tubes, a VERY personal topic.

I agree. Of course I have no way of knowing whether the Duetto can actually do 15 Hz because I have Lamhorns with DX3 Lowthers that don't play much below 60. I have them supplemented with an MBL sub that integrates very well and gets me pretty flat down to the mid twenties so I am happy.

I would assume that the speakers you heard the other Wavelength amps hooked up to had similar specs to the Lamhorn. My present amp is a 2A3 Bottlehead parafeed that I am using 300B/2.5 volt Sophia meshplates in. I hope to get some 2A3 meshplates sometime and do the comparison you suggest.

I had the VAC hooked up to some Soliloquy 8.2s that could get into the mid 30 hertz range and they were good at it. I agree that the VAC amps are a unique product and I don't hesitate to recommend them to someone who needs more power than an SET can provide. I think they are in a class by themselves in push-pull amps.