Soundhound I have heard you tout the superiority of tube gear sound for about two years so I decided to follow your wisdom and I built a stereo tube preamp using 12AU7 tubes. It has three sets of inputs and one set outputs so I can select multiple sources. I just finished it tonight and I did a little low volume listening and so far it sounds great.

My first question is how you have your preamp integrated with the 950? I am thinking of building a selector that would reside between the 950 and my 770. The selector would have two sets of inputs and a common output going to the 770. I would use an On-Off-On switch to select the desired input and pass it on to the 770. I would use the 2-channel output from the DVD player to supply the tube pre for stereo listening, and the selection switch would allow me to feed the 770 with either the 950 signal or the tube preamp signal. You had suggested in a previous post to someone that they could run the 950 through the tube preamp and then on to the main amp. Which of these two scenarios would you suggest or some other hook up scheme?

Question #2 any recommendations on a nice sounding 12AU7 tubes?

Thanks for any response and thanks for your never ending touting of the superiority of the tube, which continued to peak my interest until I decided to do something about it.

My system is actually pretty convoluted, but the simple way of describing it is:

I have the coaxial digital output of my CD/DVD player routed to the 950 and the player's analog outputs routed to one input of the tube preamp. On another input of the tube preamp, I have the 950's left and right line outputs. I can switch between the 950's left and right outs for movies, and directly from the CD/DVD player for music. I have a "calibrated" position on the tube preamp's volume control that I set it at when listening to the 950 so that the 75db calibration is not upset. The output of the tube preamp is permanently connected to the inputs of my power amplifiers (actually the active crossover network).

I would avoid placing a switch on the output of the 950 and tube preamp going to the power amp input.

I don't have any specific suggestions on tube brands. You might try reading Vacuum Tube Valley magazine which has loads of tube shootouts. www.vacuumtube.com


Now, about those class "A" single ended triode monoblock power amplifiers......


[This message has been edited by soundhound (edited March 03, 2004).]

keta:
If you haven’t seen it, here’s a chat room for tubes. Click on “Tube Lover’s Forum”.
http://www.decware.com/cgi-bin/yabb/YaBB.cgi

Also, they have some descriptions on tubes and their characters here. http://www.upscaleaudio.com/rare/rareN.htm


[This message has been edited by Spiker (edited March 03, 2004).]

I was a tube person for years. Tubes provide euphonious distortion which the brain often interprets as a desirable thing compared to the near-total lack of distortion from good SS electronics. Many folks fall in love with this sound and, being unwilling to acknowledge that they prefer sound that is distorted, come up with a wonderful array of reasons why tube sound is cleaner, airier, purer, more precise, more detailed, etc. May they be happy with whatever explanation satisfies them.

In my own case, I ultimately became more interested in precise reproduction than in euphony so I migrated to SS. But that is merely MY choice. If you love tube sound, go for it and be a happy camper.

Best regards!

------------------
The Nice Guy with the Good Ears.
"The human capacity for self-delusion is nearly boundless."

Nice Guy:

I still use a tube amp on my downstairs stereo but the ht upstairs is all solid state. Hey, the ht makes music, too so I'm happy. I've probably got 50' worth of lps and a VPI record cleaner, and a very finicky turntable/arm/cartridge combo that I never use anymore. Maybe it's laziness, but the convenience of throwing any kind of little silver disc in the machine and being able to see/hear sota software is too compelling to still wash the lp, clamp it down, clean (ultrasonically) the stylus, and bias the tubes to hear 20 minutes of music. You too?

Jay

While the purpose of this article is not to provide 'the ultimate answer,' I think it respectfully touches on several of the issues of tube vs. solid-state. He has both praise and shortcomings to list for each technology.

http://www.inventionandtechnology.com/2002/02/tube.shtml

Not only do we have a hopefully friendly debate regarding the attributes of tubes vs. solid-state, digital vs. vinyl, and so on, but we also have an underlying philosophical debate/marriage of science and art.

The engineer part of me wants my sound system to exactly reproduce the sound of a creative work performed by others – unless, of course, I don’t like the way things were done, either technically or artistically. In that case I want my sound system to somehow improve the performance! Now I have become both a technician and an artist, making technical and aesthetic evaluations, then making changes in pursuit of my goal of a perfection that’s difficult to define.

Take a look at a piano (or a violin, or a pipe organ, etc.) – marvels of physics and artistry. The varying tensions on the strings, the support structure, the hammer materials and workings, the various surfaces that vibrate, or not, in certain ways at certain times. Yet in the minds of most of the audience, the anticipation beforehand, the appreciation during, and the applause afterward go for the performer who manipulates the keys and pedals for those minutes in which the music is played. A few do, however, appreciate the artisan(s) whose skill at building a piano has given the performer an excellent instrument. A few also think of the person(s) who care for and so carefully tune the instrument. These people have contributed substantially to the performance and have my respect and appreciation.

Time is at a premium, isn’t it? (Yet here I sit typing words to friends I have never met face-to-face!) When there is time, however, I can smile at the joyful care and skill of the person who cleans cherished vinyl recordings and tunes the instruments, some that glow with orange heat, before his prized conglomeration of platter, stylus, enclosures, cones, horns, domes, ribbons and/or filaments bring to us a performance of music. It is art rooted in science and science inspired by art. I enjoy being both one who shares and one who partakes.

Sometimes we can walk away from a concerto thinking, “that wasn’t the best violin I’ve heard.” On the other hand, we can also say, “What a performance!” Much is the same for us who build and play our instruments.

I'm afraid that is a gross over simplification. Things like the distortion sprectra, the relative phase of the original signal to the distortion components, and the signal level, and thus the distortion levels must be taken into account. It is not as simple as "tube amps distort more and that is the reason they sound euphonic".

True, a tube amp will enhibit more distortion approaching it's maximum output level than a solid state amplifier. But what if you run that tube amplifier at low power levels and don't ask it to reach anywhere near the maximum output? As an example, because of the extremely high sensitivity of my horns at 106db/watt, at the levels my tube amps are run (well under 1 watt, and probably more in the milliwatt range), they actually have distortion amounts similar to a solid state amp.

It is not informed analysis to make a sweeping generalization about anything - tube amps or cars or whatever, without addressing all the possible implementations. It is all in the details! It is just as easy to make a solid state system sound good or bad as it is with a tube system.


[This message has been edited by soundhound (edited April 13, 2004).]

id have to agree with bestbang's comment about why people like tube amps, and that is why i dont like them.

I didn't mean to start a debate about SS vs tubes. I had a question for SH because I know he uses this equipment.

I didn't build the tube preamp because I'm looking for something in music that the 950/770 doesn't give me. I started awhile back trying to learn about electronics since I had a limited understanding of electronic circuits and how they work. An example would be that I knew what a diode does and how to use it in certain applications but I didn't know how it actually worked. I had no concept of how an RC circuit or inductor was used. Since I have no one to teach me I decided to read a bunch of books (which will give you a killer headache) and try and get a better understanding of what was happening. I started with some of my grandfathers books (he was an EE) and they helped but I learn best by actually seeing, feeling and testing. Tinkering with some tube circuits seemed to be the most logical path because I'm good at building things and you are able to modify hard wired circuits. It sort of became a hobby while trying to learn something.

I have built a tube preamp that I think sounds pretty good and I use it as a test mule for learning different components and circuits. Currently I have the preamp setup beside the 950 with both feeding the 770 through an A/B switch and both being fed from the DVD player. With this setup I can A/B music on the fly to compare the tubes to 950. This way I can change some capacitors or tubes and always compare then to how the 950 sounds to see if I have made an improvement or ruined everything.

Next on my tube audio list will be either an active tube crossover or a pair of amps (maybe 2A3's or 300B's). After that I'm onto building speakers with the effiency needed for these types of amps.

I got interested in this because of the knowledgeable responses given to technical questions by a few of the outlaws especially SH. Wanting to better understand those responses led me on this trek.

As proof that this is primarily for learning at this point is the tube rectified battery charger that I will build soon. I won't charge the motorcycle battery better than a normal charger but will look a lot cooler and I will have built it.