I have a tube amp question?????


How does every body here think a 12(or so) watt class a tube amp would power a set of 6ohm 87db speakers? I listen to just about every kind of music and use digital as my only source, any coments, questions and suggestions are welcome, thank you.
tireguy
Tireguy 12 watts is not a lot of power for a 87db spkr. Is this peak pwr and how loud do you like to listen to your music?
I listen to music at reasonable levels(I realize that is a vague but I have never measured db in the room) and I believe it is peak power, 12 watts kind of depressing. i did not think it would work but wanted an outside opinion before I pass another great deal by.
I know that folks that are into Single ended triode set ups get by with pretty tiny amps, but those speakers are only moderately efficient and 12 w peak is not very much at all. Other questions of relevance are room size and speaker type. If they are full range they will need a lot more juice than if they are mini-monitors. My gut reaction is that you would have a hard time driving full range speakers to anything approaching realistic levels in an average size room, but for near-field, relatively low volume listening of non-orchestral, non-rock music in a small room, you might have a chance. Now recognize that I am not a tube amp expert at all, so take this with a grain of salt.
A friend of mine uses a 17 watt/channel tube amp to drive very inefficient speakers. He knows this but they sound so good at low volume that he can't bear not using this amp. If the amp you have your eye on is a real steal and you can afford it, go for it. At some time in the future it may be great as a tweeter amp in a biamped system.
You certainly aren't going to rock the house with this amp, but if that was your interest--you probably wouldn't be looking at this amp anyway. If you are in a moderate sized room and listen reasonably close (less than 10 feet--I don't know if your room or speakers are conducive to that setup), you will probably be so engaged by the tube amp, that I doubt you will be looking for more volume. The only other aspect I would consider is the ohm (loading) of the speaker. I know you said 6 ohms, but that's nominal. You might want to be sure that it doesn't dip to some very low impedance in certain instances. That can create some difficulties for some tube (and other) amps.
I once owned a 30 watt tube amp that I used to drive Vandersteen 2c's (88db) in a 12 by 26 room. It occaisionally clipped and distorted so I would think that 12 watts would not be enough, however this is only my opinion.
I doubt that 12 watts into the given speaker load you described would be very satisfying. If I couldn't audition I wouldn't do it.
Here's a possibility. Get your hands on a scope or someone with one. Hook up any kind of amp or receiver that is greater than 12 watts. Now power is equal to Volts squared over Resistance. The amp was probably rated at 8 ohms. This computes to about 10 Volts RMS which is about 14 volts peak. That's 14 plus and 14 minus. Hook up the scope to the speaker terminals and see how often you exceed 14 volts while playing music at a level that is satisfactory.

My guess is that you won't be happy.
12 watts is to small for an 87db speaker unless you are using it for light background music.

I use 8 watts of 300B on 92db speakers with good results. Not a wall shaker but I don't like real loud music. The same 8 watts is not enough for a 90db speaker.

15 watts will do 90db quite well.
Hi, Tireguy, there is a guideline for power:
the efficiency of your speaker is 87 db means with
1 watt input, they will produce 87 db sound if you
measure sound pressure on axis, 1 meter away from
your speakers. If you want to increase 3 db, you
need to double the power of your amp. For example,
you need 2 watts to get 90db, 4 watts to get 93db
and so on.
I hope this will help you a little.
I've run across a rule of thumb that you want around 102 db. So 10 watts will get your 87 db to 97db. 20 gets you to 100db. 30 watts should have a good chance of working out.