300b lovers

They now dominate high-end audio, which was not true thirty years ago. I remember going to some CES shows with hardly any tube amps at all, never mind DHT’s, and now they are everywhere.

While it is correct that there are more tube amplifier producers (many of whom show at audio shows) than there was in 1958, its incorrect to say that tubes dominate high end audio (most of these producers are very low volume). The larger players who produce solid state products are still the bigger sellers.

I should have been more clear when I mentioned direct coupling as a method. Specifically, I meant using a cathode follower which is direct coupled to the power tube so that the bias of the power tube is obtained from the driver tube. For this one would need a B- supply, but if the best reproduction is a goal then that cost isn’t important. IMO using a driver tube in this manner does not result in higher ordered harmonic generation, at least insofar as our OTLs seem to measure out. In them the higher orders fall off at a faster rate than any SET I’ve seen. They sound smoother too. One thing we sorted out from doing this over the years is that the plate needs to be heavily bypassed to prevent IMD and harmonic generation. In our amps we found we had to use bypass capacity values an order of magnitude higher than one would typically expect; after trying lesser amounts we found the seemingly excess amount made a difference to the distortion. IMO this aspect of cathode followers is poorly understood.

@tuckia08 Thanks for your comments.   I have heard a number of 300b now, but not the new WE 300b and I have not heard the European expensive tubes.  When I tried the Linlai WE300b copy I stopped looking.  I can get them for about $750 a quad from my supplier and so far the 4 or 5 quads have all been perfect with no issues.  As for sound.. well they stomped all over all the $400-500 per quad tubes from China, and the Gold Lion reissue, which is a nice tube, very well made, but just cannot match the clarity of the Linlai WE300b copy in this push pull Blackbird.

The Monolith OPT is based on their standard summit series core.  I don't want nano or amorphous.  The amps have incredible micro detail and the tonality and timbre of instruments and vocals are spot on to my ear.  They are rich and full sounding.  I am happy with the summit cores.  I was playing records last night because I am burning in a phono stage for a customer and shipping it today.  I had not used phono with this final version of the amps and I have to say that I heard subtle details in the familiar records that I had not heard before, even with earlier prototypes of these amps.  The summit series transformers do it for me:)

I too will be interested in user comments.  We hope to be making them in November!

Yes, the Lampi Pacific is outstanding.  Mine is modded a bit and I am considering sending it in for their upgrade.  They will put the Horizon digital engine in there for about $4K, and do a few other things.  Spendy.  Once the 300b project is off the ground maybe I will gamble the $4K:)   But the Pacific is just stunning as it is.  I run a quad of NOS 46 tubes with adapters, so they are essentially a 45.  The clarity is astounding.  I wish we had this quad at the Pacific Audio Fest in that Pacific that Fred, the NA distributor for Lampi loaned us.  Anyway, enjoy your Horizon.  An end game source no doubt!  Once you get a DAC that good... you cannot go back.

Back when I was playing around with 300B’s, I found that each brand had its "sweet spot". The authentic 300B’s, and the exact reproductions, seemed happiest between 65 and 75 mA. The European super tubes, between 72 and 85 mA. The monsters with giant 65-watt plates are probably happy between 80 and 95 mA. Power supplies need to deliver at least twice the quiescent current, preferably more.

If the current is a little low, they are rich-sounding, but also murky and dull, and if too high, super detailed but also wiry and hard-sounding. Very much like setting VTA in a phono cartridge ... there is a correct setting, and you know it when you hear it.

There is also a tiny range of allowable filament voltage, from 4.85 to 5.05 volts. This can change the entire character of the tube, from very dull but rich sounding to wiry and hard. For longest life, it should be exactly 5 volts, and leave the subjective tuning to setting the quiescent current.

The B+ voltage only had a minor effect compared to the other two parameters ... well, three, counting tube swapping. The other indirect-heated tubes aren’t as temperamental ... put them in the usual range, and they sound fine.

Don thanks for sharing what you are hearing with the OPT and tubes. I’ll have to hear these somehow someway. 
 

I share my tube experiences because I know how hard it is to get all of these expensive things in one session so they can be A/B/C/D compared. Some I owned, some were loaned. Goes without saying that everyone will find their own preference. But meaningful differences exist. I roll till I find the right ones then stop. Some never do.

I was mistaken. Thought you did the PAC 2 upgrade already. From what I hear (from Fred) it is money well spent. If this was an option when I had my Pacific, I would have gone to 2 and stopped. End game. The PAC is DHT, the Horizon is not. Some consider the 46 as the best option. I never had any to try. I can say the EML 45 globe mesh are pretty special in a Thomas Mayer amp and the Pacific. But rare unobtainium now. But my everyday Pacific tubes were KR RK PX25. I ran these in my amps too, which is kind of funny.

....I try Real Hard to avoid 300 ib lovers.....

Oh.....

;)