[JerryM]

rcag,
Nice write up!!! Thanks! 

If you could acquire either amp, money no object, which would you choose based soley on sound?

Have fun,
Jerry

[rockadanny]

Kudos to Frank for hosting this trial - he is a special person.
I wonder how many other designers have the confidence to do a shoot out, guts to publish honest results, and graciousness to allow this type of thread to exist in their own circle without throwing a hissy?

[avahifi]

Both amps had a nice big sound stage with a great front to rear and left to right presentation.  The AE25 lost some of the singers in the chorus though.

We will have the new Ultravalve vacuum tube amp on display at the RMAF, done except for the faceplate will not be finished, just bare aluminum, the parts got here too late to do that.

Regards,

Frank Van Alstine

P.S.  Oh yes, a client sent me a pair of 6U8A tubes to try in the amp (Ultravalve) instead of the stock 6GH8A tubes.  They worked just fine.  However, neither I nor rcag_ils could hear any difference between them at all.  However the 6U8A put out a couple of volts less power on the test bench.  The amp clipped at 21V peak with the 6U8A tubes, 23V peak with the 6GH8A tubes.  I am sticking with the 6GH8A tubes as they are a known item in this design.  By the way that is 33 watts RMS both channels driven into 8 ohm.

[rcag_ils]

The U70 is a dynamic, clean amp full of energy, with linear spec, and accuracy. I am not sure if all amp designers use the same test parameter as Franks though.

If you could acquire either amp, money no object, which would you choose based soley on sound?

If I walked into Frank's shop 8 years ago, and he did the same demonstration with the same equipment, I would probably pick the U70, (we figured the price is about the same in 2001 dollar) because the U70 is probably less picky about speakers, solid design and more "right" to the sound. To like the AE-25, you have to believe there something called "tube" sound, and it's not designed to give you "kickass" bass. The speakers that I use with the AE-25 are rated 90db in sensitivity, over all it's a neat amp to play with.

The AE25 lost some of the singers in the chorus though

I noticed that too, it could have been masked by the AE-25 loose, or "muddy" bass, I wonder if placing the mini monitors a inch or two apart would cure it, the bass that these mini monitors put out is truely amazing, I noticed there's a big port in the back of the speaker cabinet.

Now I am armed with real world spec, as inquisitive as I am, with any luck, I plan on contacting the AE-25's manufacturer and get their take of the test result.


 

[Art_Chicago]

Kudos to Frank for hosting this trial - he is a special person.
I wonder how many other designers have the confidence to do a shoot out, guts to publish honest results, and graciousness to allow this type of thread to exist in their own circle without throwing a hissy?

+1,  it is amazing how easily Frank agreed to do it!
And the fact that Ultravalve is a clear winner of the contest does not prevent Frank to continue this thread