Speakers for low power tube amps

[airdronian]

Looking for some observations from the forum on speaker performance with an approx 30 wpc tube amp. Intend to upgrade a fairly inefficient pair of B&W CM1/2 at some point.

 

[The Computer Audiophile]

I think Rick can probably offer a real good opinion on this one.

 

[rom661]

It really depends on a variety of things. The CM1 is fairly low sensitivity so you are not going to get high levels out of it. How large your room is and how loud you like to listen are going to be major factors. Keep in mind that power rating is a measurement of how much voltage an amplifier can drop over an 8 ohm resistor on a test bench. That would be fine if speakers were 8 ohm resistors. They are reactive, meaning that their resistance changes at different frequencies and that they are also capacitive and inductive. What that basically means is that some speakers demand a lot of current as opposed to voltage and the power rating doesn't reflect that unless you compare an 8 ohm rating to a 4 ohm. Having said that, tube power amps are better at voltage than current delivery.

 

The other thing I would caution you about is the tonal response. Traditionally, tubes tend to be warmer with a smooth, possibly slightly rolled off top end and warm bass but less bass control and not as much extension. The CM1's tend to go in the same direction. They are a very nice little speaker that can make a solid state amp that may be slightly analytical sound very musical. However with a warm, less articulate tube amp it could be too much of a good thing. I don't know what tube piece you are looking at. Some of the recent designs are much less euphonic and more controlled than the traditional tube sound.

 

After all that hot air, my best advice is to listen to the combination you are considering. Tube power amps tend to interact more with the speaker load due to their higher output impedance. In other words, they sound a little different with each speaker.

 

If you like the body and "soul" of tubes and are interested in the CM1's, I would be more inclined to do a tube preamp and a smooth solid state power amp.

 

Again, listen and trust your own ears.

 

Rick

 

[Wavelength]

Air,

 

30w's is a ton... i only have 4 watts with my speakers being 96dB I get really full sound. I would suggest looking at some of the Cain & Cain, Vaughn (see my CES footage on my News page), Rethm or classic speakers like DeVore and Reference 3A.

 

Thanks

Gordon

 

[rom661]

I agree, Gordon, 30W is lots of power for 96db sensitivity speakers. It's a tiny amount of power for the 84db CM1's - more like 1 1/2 W in terms of comparable SPL.

 

Best wishes

 

Rick

 

[airdronian]

This is what I was anticipating, and planned for a speaker upgrade that would better match the tube output. The speakers I demo'd have a 91db sensitivity. So they will be on the list to check out when the time comes, as well as the makes described in an earlier post.

 

Thanks for the feedback.

 

[Face]

Tannoy makes some pretty efficient speakers and monitors. I run a pair of HPD-385A's in my main rig. I also have a pair of Saturn S8's, S8LR's, 6.5" studio monitors, and a S8C.

 

The HPD's sound great with my 270wpc SS beast and also with either my Dynakit ST-70(35wpc) or Heathkit AA-111(18wpc).

 

Mike

 

[brucemax]

Cain-Cain speakers (any model), Decware HDT (I have a pair and love them), Avant Garde horns, Horn Shoppe horns, almost anything with Lowther drivers. Really there are many great, simple speaker systems that work well with low power tube amps. If you like making your own amps with kits I recommend the Transcendent Audio kits or Dr. Bottlehead kits.

 

Have fun.

 

[airdronian]

Well, I never said I was quick.

 

Recently upgraded the B&W's (owned since '91)and went with the big brother to the speakers I originally demo'd with. These are a Monitor Audio RS-8. I had previously demo'd the RS-6.

 

There were a few reasons behind the choice. No they are not perfect but I think I've done well overall.

 

These have a 91 db efficiency and it's like night and day compared to the B&W I formerly used. Kind of like having doubled my amplifier power to boot. The dynamics are wonderful. I can now listen in triode mode at about 15wpc which was unrewarding before. I prefer the sound in general with this setting.

 

Will be bringing in a new set of power and preamp tubes soon, interested to hear the results. After that I plan to reposition the entire system in the room, and with any luck this year I will be upgrading the DAC in the system. It helps out budget wise to stay a couple years behind the times, and the reviews on this site remain a useful reference.

 

Thanks for your comments.

 

 

 

[The Computer Audiophile]

Hi airdronian - Great to hear. Thanks for sharing :~)