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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
lowrider57's avatar
lowrider57
5,417 posts
 
OP; what speakers will you be using?
Impedance will determine how well an amp drives the speaker; ie, a speaker with an impedance curve that stays in the 8ohm range will be easy to drive. The 88dB sensitivity may be on the low side but is less important if the speakers have an easy load to drive.
If you need high SPL’s in a large room, higher sensitivity speakers are required.
So, need to know more than the nominal impedance spec, although 50 to 60wpc may be fine.

The tube which has the most impact sonically is the gain stage input tube, often a 12AX7. Power tubes will provide the timber or tone of music; warm or neutral, bass and treble extension.
Transformers play a very important role in amp implementation. They have a sonic signature and the amount and quality of current delivered will affect speaker performance.



jjss49's avatar
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jjss49
6,612 posts
 
you are asking a question that takes a short book to properly answer

i suggest you do a search for something like ’hifi tube amp basics’ on youtube, and watch several entries that pop up - you will educate yourself faster than reading peoples' snippets here
hilde45's avatar
hilde45
4,974 posts
 
FWIW, I have Quicksilver 60wpc monoblock tube amps and at first I thought I had to have high sensitivity speakers. I did try some at 92, 93 db and they had an easier time than speakers I tried at 87 and 88 db but I have to say I found that the Monos were perfectly fine powering speakers as low as 87db. They sounded delightful and not at all underpowered. I do suspect that a lower powered tube amp might have had more trouble, but my QS has a honking transformer and easily controls those lower db speakers — which I liked better. Impedance, as lowrider57 said is very important. I had 92 db Focals which had a bad dip in the 4 and sub-4 ohm region, and that proved a problem with the sound, in my setup.

As others here have said, this is a huge topic, and I will admit, I am a newbie. So all I am saying is that I *thought* I had to rule speakers "under 90 db" out of consideration -- and I found that proved false by actual experimentation. Also worth noting: in my space, I only need to play speakers about 8 feet away, at about 80db volume to sound good an loud.
three_easy_payments's avatar
three_easy_payments
2,097 posts
 
While speaker sensitivity is important when considering tube amp matching, you should place as much weight, if not more, on impedance (how easy the speaker is to drive).  One reason Joseph Audio Perspectives (eg) work so well with many tube amps is because they're 8 ohm speakers that never dip below 5.5 ohms.  Yet their sensitivity is only around 84dB.  Tube amps 50w and higher should work well with them.
dsper OP
663 posts
 
The speakers in question are Tyler Acoustics. Tyler advised me they are 8 ohm 88 dbl and should not dip below 6 ohms. 
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