Pick a Pick a Preamp

[Lazarus Short]

The seasons are changing, and I'm getting the itch to get my main system back together. Working backwards from the Vandersteen speakers, the power amp is easy: the Proton AA-1150 it sings so well with. I did make up a bi-wire rig for the two. The choice of preamp is more open - I have an Aiwa C30 (needs work), a Luxman A-007 (can be used as a pre), a Marantz AV600 tuner-preamp, a Denon AVR-1400 (can be used as a pre) and an FX Audio Tube-01. For those not in the know, the Tube-01 is a Chinese single-channel pre with two vacuum tubes and a volume control. Mine has vintage USA tubes and 12 VDC battery power.

I set up the Denon and the Marantz so I could switch back and forth, using a Radio Shack unit that switches sources instantly. I was careful to use the same type of cables with each. With gain-matching by ear, I could not hear much difference, nor could my house guest. Then I put the tiny tube amp in place of the Denon and it was the winner in an instant. I won't even bother with the Luxman.

 

[mlucitt]

Tubes always "sound" better because the harmonics are natural sounding to the human ear.

 

[laatsch55]

Unless they're not biased right...

 

[mlucitt]

Unless they're not biased right...

You are so right.
And, I should add - many times tubes are not "better" on paper or when viewed on the test equipment.

 

[Lazarus Short]

Unless they're not biased right...

Does that apply to preamp tubes?

 

[laatsch55]

Laz, don't know enough to say..have you got a manual?

 

[mlucitt]

On my previous preamps, the tubes were "grounded grid" so no bias was necessary. I think it is more critical with the push-pull pair power tubes.

 

[Gibsonian]

I have that little FX audio tube pre. It is pleasant sounding but longterm I couldn't do it in my system. Too much distortion for my ears. At low listening levels was fine, but anytime higher volume levels needed the distortion added by it just wasn't clean enough for me, didn't enjoy the music as much. Similar to but not the same as listening to overcompressed CD's. Ok at low levels but crank em and you wanna instantly turn it down. The pre is so cheap I'll keep it for playing around but in main system it won't be going back in. I could see it if I listened at background levels mostly. Different strokes for us different folks.

 

[Lazarus Short]

I have that little FX audio tube pre. It is pleasant sounding but longterm I couldn't do it in my system. Too much distortion for my ears. At low listening levels was fine, but anytime higher volume levels needed the distortion added by it just wasn't clean enough for me, didn't enjoy the music as much. Similar to but not the same as listening to overcompressed CD's. Ok at low levels but crank em and you wanna instantly turn it down. The pre is so cheap I'll keep it for playing around but in main system it won't be going back in. I could see it if I listened at background levels mostly. Different strokes for us different folks.

Are you using the stock tubes? I went to vintage military-grade US tubes (5654 IIRC) and battery power (got hum with every power supply I tried). However, I will keep in mind what you said.

 

[mlucitt]

Are you using the stock tubes? I went to vintage military-grade US tubes (5654 IIRC) and battery power (got hum with every power supply I tried). However, I will keep in mind what you said.

I heard an interesting quote a while ago that stated, "Tubes wear due to the heat and emission of electrons from the various surfaces to the plate, some more than others, they have a finite life and you cannot slow down or stop the process of deterioration in use."
Clearly, transistors do not have this issue. When tubes were inexpensive, this was not a serious problem, just re-tube. Today, the vintage tube market is thriving due to the belief than newly manufactured tubes from Russia and Yugoslavia do not possess the tonal and other qualities of the vintage tubes.
I'm not sure about that, but people are paying $1700.00 for a pair of Telefunken German 12AX7 dual triode preamp tubes, when they can find them (about 8 rows down in the tube listing, under the nice descriptions of the various vintage brands).
https://www.audiotubes.com/12ax7.htm

 

[Lazarus Short]

Odd you should say that, for I read elsewhere on the www just this morning that a preamp tube should last your lifetime...

 

[Gibsonian]

No I purchased some tubes to replace stock. Haven't tried battery power but will in the future. Might use this pre for my portable sandbar stereo, where battery power is already present.

 

[mlucitt]

Odd you should say that, for I read elsewhere on the www just this morning that a preamp tube should last your lifetime...

I was speaking generally. It depends on how the tubes are used; if the plate voltage is specified at 300VDC, and the tube is run at 200VDC it may outlive you. Some power amps run the tubes way above the specified plate voltage, this will shorten their life. Ask HAM radio old timers.
Tubes are like light bulbs, the filaments have only so many cycles in them, for example. So many exceptions... 6.3v filaments last longer than 12v filaments. Preamp tubes are not generally run hard. But by design, they degenerate over time, even if that time is very slow.

 

[Lazarus Short]

The other day I picked up a battery charger sized for the FX's gel-cell. It took several hours to charge, but there was a handy green LED to tell me of the full charge. The charger did need a muffin fan blowing on it to avoid it getting too hot. I put the FX on the bench and hooked up a Phillips DVD player to it and my Yamaha M-35 amp. Speakers were Sony.

It all sounds good together, but the speakers limit volume and bass somewhat.

 

[Bob Boyer]

Odd you should say that, for I read elsewhere on the www just this morning that a preamp tube should last your lifetime...

The main reason I sold off my Counterpoint SA-5000 preamp was the cost of maintaining matched, super quiet 6922s in the phono section. For whatever reason, and I'm willing to admit the possibility I was just hearing things, those tubes started getting noisy after about a year of use. I'd move them over to the line section, where they did fine because signal levels were so much higher, and the line tubes would bump down to the next nothc - and so on. Still, at the time a super quiet pair of 6922s was $180 - $200 from Mike Elliott. Doing that every 9 months to a year for a few years wore me out at a time there wasn't a lot of cash flow.

Don't get me wrong - I loved that preamp, and the companion NPS-400 stereo amp, which was a hybrid design. They were great pieces and some days I regret selling them. That said, they did like to eat tubes, particularly the SA-5000.

 

[Gepetto]

I was speaking generally. It depends on how the tubes are used; if the plate voltage is specified at 300VDC, and the tube is run at 200VDC it may outlive you. Some power amps run the tubes way above the specified plate voltage, this will shorten their life. Ask HAM radio old timers.
Tubes are like light bulbs, the filaments have only so many cycles in them, for example. So many exceptions... 6.3v filaments last longer than 12v filaments. Preamp tubes are not generally run hard. But by design, they degenerate over time, even if that time is very slow.

Enter the age of solid state, many of us still can recall the ads at the time touting that no longer did you have to replace unreliable tubes etc...

And those were the days of crappy capacitor coupled power amp output stages...

 

[pennysdad]

Like anything, what we like at any particular time, depends on too many other factors.
I like tubes/valves. I also like solid state. As long as the music is good, I don't really care what I'm reproducing it with.
After playing an album for 5 minutes, it doesn't matter anymore. Your mind adapts....

 

[pennysdad]

.... but as far as valve power amps are concerned, there's one that really shines for me.
This one. It should fetch well over AU$3k. Pro'ly a lot more if I was bidding on it.

 

[pennysdad]

Enter the age of solid state, many of us still can recall the ads at the time touting that no longer did you have to replace unreliable tubes etc...

And those were the days of crappy capacitor coupled power amp output stages...

I remember back in the day, when all musical instrument amps were all valve, and then Yamaha introduced their first solid state thing, and it was dreadful.
Gone was all the harmonics, distortion and 'fatness' that all guitarists were craving for.
To this day, valves still rule on stage and in the studio....

 

[J!m]

My opinion, a line level preamp can be tube. As Bob noted earlier, a phono stage is either going to have multiple gain stages (i.e. several tubes), or try using less, with more gain per stage. With multiple tubes, you run the risk of added noise. With few tubes, you run the risk of more distortion and/or shorter life, as Bob found. As a designer, Mike Elliott was under a lot of pressure to perform at a price point.

I use a Perreaux preamp, which is solid state and line stage only. Any my phono preamp is an Aragon 47k, which is also solid state. I guess I'm lucky, but I have no noise or distortion (that I can hear) over the surface noise of the record itself.