Tube amps and speaker ohms

Divad, I am running a Tube Audio Design-60 with Vandersteen 2CE sigs (86DB I think. This amp runs 60 watts ultra and can be switched on the fly to triode (30 watts). This amp has plenty of juice for the vandys. I listen mostly to classic rock at room filling but, not loud levels and the vandys really sing. See Larryx7s post above. The TAD-60 can handle many EL-34 type tubes and is easy to bias. Check out the reviews on this amp. I haven't heard many other tube amps to compare but, I bet that it competes very well with amps in its $1300 class...

Eagleman

Newbee, can you provide a link on the Tyler website that contains impedance specs? Thanks.

I can't quite wrap my head around why some tube amps work with 3 ohm impedance loads and others do not. The Leben CS-600, which produces 32wpc with 6L6GC tubes sounded anemic and downright awful on the VR4 speakers, yet it is sweet, musical and downright incredible on the 5.5 ohm minimum Castle Howards.

The Rogue Cronus at 55wpc...just 13 watts more...brought the VR4 speakers to life. Yet, the Cronus has smaller transformers than the Leben.

On the other hand, the Cronus sounded congested and coarse on the Castles.

I'm sure someone like "Atmasphere" might explain it, but I'm at a loss. I do know that in general tube amps work better with higher impedance loads.

Tvad, This info came from the horse's mouth. I've never seen it in print, its what Ty told me.

Re impedences, there was an excellent thread in which Duke participated, within the last 6 months, where in not only were speaker impedence loads discussed but amp output impedences were also discussed. Amp putput impedences are seldome discussed and their impact is not generally understood. Most folks assume they are constant but they are not, they rise and fall with frequencies and have considerable impact of the sound which is produced by a speaker. You might be able to ferret it out by looking up some of the threads in which he participated. And, I think you are right the Ralph could help explain, but I can't recall if he participated in that particular thread. Maybe you could start a thread and get a discussion of this going and invite Duke and Raplph to participate. This may help you. Good luck......

Thanks, Newbee. Personally, I believe it'd be beneficial to Ty's potential customers if he published some impedance specs, but in the end that's his business. I'm only speaking as a consumer.

Though I realize they vary, I'm not that interested in delving into amplifier output impedances. No amp manufacturer publishes these specs, so it's info not readily available to buyers, which frankly makes Stereophile's reviews with bench tests so useful. It'd be a PITA to rent the required testing gear, and to learn to bench test amps that I buy or bring in to demo.

I'll trust my ears based on choosing gear that meets general guidelines. The Leben/Castle combo works. The Rogue/VR4 combo works. Overall, more amps work with higher impedance loudspeakers than with speakers that have low impedance dips.

For me, this is the "take away" from the thread you referenced in your most recent post.

I am fast coming to the conclusion to stop looking at "watts per channel" as an efficient means of determining how powerful an amplifier is.

My experience tells me that the power supply and transformers play the biggest role in this, as opposed to whatever reading was obtained when the amp drove a 1 KHz signal through an 8 ohm resistor, or what a company chose to rate an amplifier. Music is not a test tone, it is dynamic, and loudspeakers are not an 8 ohm "dummy load", they are FAR more complex.

Tubes, also seem to have something to do with this whole thing. For example, a 2A3 has less "measured" power (usually, about half as much) than a 300B, but in my experience, the 2A3 does a better job in providing "real world" power to a loudspeaker than a 300B. Similarly, a KT77 looks SO close to an EL34, but they are very, very different tubes, with very different power characteristics. And, for what it's worth, a KT88 is a strong tube. At least as strong as a 6550 or KT90, though the Ei KT90 tube seems a bit more extended in the lows.

In no way am I saying that measurements are something to completely ignore, but clearly, the engineers designing these tests have yet to figure out what is the important criteria, and the means to go about testing it. Until I am told of a better way, playing music through an amplifier and a pair of speakers, and listening with my two ears is going to be the way I test...