Where vacuum tubes work best

[dz]

You confirmed what my Father told me, it was true in the 1970's as well as today. He told me to invest in a good Tube Pre-Amp and a good Solid State Amp with 'quality' Caps.

[joyoffilming]

Wow!
What high level of honesty, admitting that somebody else's front end design sounded better than his own, putting his companies bets on the other guy's design.
That whole attitude is what I and so many other subscribers of your chanel love so much.

[palehorseone]

Thank you SO much for this Q&A series, Paul. I love your candor and the obvious pleasure you derive from sharing your wealth of knowledge and experience.

[andrewryder]

Hi Paul. Love these segments; love your products. Unfortunately, though, this answer is wrong. Let me explain:
In Russel Hamm's May 1973 report in the AES Journal (Volume 21, # 4), he conducted the very shootout you're describing — a double blind A/B between tubes and solid-state devices, except that the shootout was also broken up into various stages. In other words, comparisons were made in the front ends — (microphones preamps, phono preamps, line stages) AND in the amplification stages. Not only were subjective (listening) tests performed but performance of each was extensively analyzed.

The result? The MOST profound difference between tubes and solid-state devices occurred wherever there was an interface, e.g., speakers, cutting lathes, microphones, turntable cartridges. The differences in line-level reproduction (while they DID exist) were not as noticeable.

It is, therefore, MOST advantageous (in every case except a phono preamp) to have the tubes powering the speakers. Now, you may say, "well then your at the mercy of the output transformer's quality", and this would be true, But remember, we're talking about a "cost is no object" system here, so you can have a top-quality (albeit expensive) output transformer that will NOT exhibit the phase distortion and IMD that many cheap ones do.
If you do so, I can PROMISE you that the tube amplifier (even if fed by a solid-state preamplifier) will result in better subjective sound quality than a tube preamp feeding a solid-state amp, (even a PS Audio, Krell or Mark Levinson ).

This, by the way, is a VERY common misconception — that the best way to get the advantages of "both world's" is to use a tube preamp and a solid-state amp. In fact, you're actually better off doing the OPPOSITE. I, in fact, USED TO believe so myself; It wasn't until I started "flipping the script" in my own designs that I realized how wrong I'd been*. Tubes can be microphonic, so you'd (ideally) like to feed them a strong signal (i.e., one that is ALREADY preamplified), and the use of an output trafo on a Class A tube circuit not only serves to protect the speakers (as transformers can't pass DC) but also acts to cancel out many of the distortions inherent in loudspeakers (by creating similar distortions in the inverse, much the same as a push-pull circuit can cancel out even-order distortions inherent in single-ended designs).

Ever since I've realized the benefits of coupling tube output to transformer to speaker, I've been fighting the same misconception I used to have as well, that tubes are best used in the front end. It's simply not true.

*Note: I've been designing audio components for over 35 years and ran a recording studio for over 25, so had the benefit of being able to compare the playback of a musical performance to the actual performance I'd just heard (while tracking it), which is the best way to judge accuracy.

I WILL SAY THIS: Putting tubes in the front end makes a big difference if you can't get a tube amplifier with an excellent output transfromer. Also, signal tubes "break in" and "open up" more quickly that power tubes, so you may need to get some hours on the equipment before the advantages of the power amp become obvious, but if you can get a first-rate tube amp and let it burn in, they will!
Try it yourself: compare (double-blind) a high-end tube amplifier to ANY solid-state amp in the same system; (gIve the tubes 25 hours or more of use first if the amp is new).
If you thought the difference in the front end was big...

[junzhang]

I use tube amp to power sennheiser HD600. Heaven.

[wayoffthegrid]

First of all, this youtube series you've been producing has been fascinating! That said, I'm curious why the "Sprout" product-line isn't offering a "tube-buffer" either as an add-on option or as a stand-alone device that shares that same chassis-design as the Sprout??  (Hint, it'd be great if you made this with both balanced and unbalanced in/outs so it could also be a signal-converter between different pre-amps and amplifiers, and also by all means keep the power supply INSIDE the case! The world doesn't need any more "wall-wart" system-clutter, lol)

[dmgmail]

I've gone back and forth between ss and tubed pre. No matter which one I run, I always feel like I'm missing something the other one does better. Recently it's dawned on me my biggest mistake may be I'm trying to choose one that does both and if I ever found that unit it probably wouldn't do either one great. So I've concluded the only solution is to have both, and rum thru a switch. Now I need a good switch with no measurable loss(🤔🙄😶) it never ends....

[graxjpg]

Hey Paul, if you're looking for a cool place in Texas to visit, San Antonio has all the coolness of Austin without all the lameness of Austin! Haha

[phreal]

The way you've explained the shootout made me laugh so hard. Very honest and informative Q&A. thank you.

[acoustic]

If you're gonna use a tube buffer, you might as well use a tube preamp. Unless you don't use a preamp.

[L.Scott_Music]

Tubes in the front end also last a lot longer.

[Matasky]

So he's saying tubes in a preamp is more beneficial than say a tube integrated amplifier, correct?

[tcngr]

Also, we don't need so many tubes in the preamp as compared to the power amp, which means that the maintenance cost is must economical! I am using tube preamp + ss power amp.

[giannagiavelli]

I spent 3, 000 on my massive marantz sr-18. It has a humungous torroidal transformer and burr brown circuits. It's fine for rock. But when I want violin, sax, piano, vocals, jazz, opera, classical, cello, well theres no contest. My 300B SET blows it out of the water.

[buttonman]

This is excellent, been thinking about integrating tubes into my system. Always thought the front end seemed like the most logical spot.

[GillieWilson-zedf]

I am a harp player, and I have all tube amps .Get this, 2 Gibson 1941 suitcase amps . The oldest is pristine and uses 2 6sq7 preamp tubes, a
I sub 6sr7 metals to tone down, 2 6v6 which I use RCA cokebottle, and a 5y3 rectifier that I subbed a BENDIX 6992 . Second Gibson uses different preamps, 6jc7. Same in power, 6v6 and 5y3 . An Ampeg Jet, rebrand as Noble . 6sl7 preamps and 2 6v6 push pulls, 5y3 rectifier.. A fine Blackheart Handsome Devil with 12ay7s for preamp and EL84 power tubes . Then, my gigging amp, VHT Special 6, class A, a 7442 preamp . . . 12ax7 one triode and 12au7 the other, then a cokebottle Sylvania 6l6 blackness for a power tube. A GE 5881 works good as well .

[robertclark]

My housemate of years ago had a Copland amp with valve pre-amp stages and solid-state output stages... I have never heard a better sound from an amplifier

[drbarney]

If you do not push tubes so hard two things happen. Distortion goes up when you turn up the power. They do not last as long. By using bigger tubes you do not need to push them hard. They last for many years and they sound better. When they do wear out they are cheaper to replace than the labor of hiring a technician to find and change a bad transistor. That is why I use commercial AM radio station 833A transmitter tubes for my SET amplifier. They can handle 2000 to 3000 plate Volts but with only 1000 Volts drawing 120 ma, they are more than loud enough with low sensitivity Magnepans. PS Audio really ought to try building a prototype 833ASET. You can use a Hammond 1642SE output transformer which is rated to 300 ma before core saturation and pot tested to contain several thousand Volts. Just feed the grid with about 600 Ohms from a headphone or low power amplifier at zero grid bias (transformer between 833A grid and ground.) The 10 Volt 10 Amp to heat the cathode is a little tricky to design, but I use a 4.5 Farad capacitor in the final pi filter. Tungsten cathodes have to be heated with pure DC.

[MrRobfarr]

Hi Paul, your descriptions are great, but why don't you show and demonstrate these products so that we can really appreciate them.

[massimilianodimario]

Tubes=voltage amplification SS=current capability