Never Owned a Tube Amp and Want Advice


Hi All, 

I have never owned a tube amplifier before and am planning to purchase one with a minimum of 50 watts per channel to mate with 8 ohm 88 dbl speakers.

My hope is experienced audiogoners will share their expertise regarding how to approach this. While I realize listening is the best way to learn about sound and compatibility; I want to learn a better understanding about brands with less maintenance and longer tube life, how to decide between mono or stereo,can a newbie play with bias or is auto biasing a better first choice, etc.

I would also appreciate what to look for in selecting a used tube amp to identify one that might be in need of repair. For example, with solid state depending on the brand, capacitor replacement can be more of a concern. Any advice on what to look out for or ask about with used tube amps would be appreciated.

A big question I have is how to understand the relationship between power tubes like E34's, 120.s, etc. and, I guess the driver? tubes like 12au7's and 12at7's. That  is to ask which is more critical to the overall sound of the amp? FWIW, I routinely tube roll with my preamps.  

I 've read through a number of threads but maybe someone can point me to good ones I may have missed. 

Thanks for listening,

Dsper
dsper

Showing 1 response by davehg

Man if I was new to tubes, this thread would leave me confused and wondering where to go.

Forget the numbers for a bit. Just go and listen to a few tube amps in your budget range and a few slightly higher in price. Listen to a range of tube types - EL34’s, 6500/KT88, and SET amps such as 300b tubes. You may find you prefer the sound of specific tube types, although newer amps seem to blur the line between how specific tubes should “sound”.

Power is important but it shouldn’t dictate your decision, it’s just a factor. I’ve successfully run low powered SET amps with less efficient speakers, and I’ve had higher powered amps struggle to sound good with super efficient speakers. Try out with your speakers and read forums to see what has worked well with other owners who use your speakers.

A pragmatic factor with tube amps is the number and cost of the tubes. You’ll be tempted to try different tubes which do sound different, and that is far more costly on a 300b amp than with an EL34 amp, and costly on amps that use a lot of tubes or esoteric, NOS tubes. I try to avoid amps that use tubes I can’t easily source online.
I currently use a 300b 10wpc SET amp (Woo WA5) to drive Devore Nines, which are tube friendly. The same amp did well with ProAc Super Tablettes which shouldn’t be as friendly. I’ve owned more powerful EL34 amps (the mighty AirTight ATM3 mono amps) and will shortly own a Leben CS600x, which is 30ish watts. I’ve had failures with well lauded amps (the WAVAC being an example that didn’t work for me) and pleasant surprises with amps that were not well known (remember the Antique Sound Labs)?

There are few rules that seem to be absolute with tubes, other than avoiding pairing with speakers that are low impedance (and not running unless you have speakers connected as was mentioned). Tube amps are fun, wonderful creatures that will delight you, and if you choose well, will encourage you to try different tubes and enjoy. Biasing is not hard with most amps - a ten dollar multimeter and a screw driver is all you need in most cases, and most newer amps use auto bias.

My favorite reasonably priced tube amps (may mean buying used) of those I’ve heard, and which mate with a decent range of speakers, include:

VAC Avatar SE
Leben CS600 series
Line Magnetic amps
Audio Research VT60
VTL amps (newer)