Posted by Duke [ 63.87.108.184 ] on October 30, 2006 at 22:20:44:

In Reply to: Re: How did the RMAF go - several links posted posted by Duke on October 30, 2006 at 22:06:58:

The amplifier used in Room 9002 was the Atma-Sphere S-30, a 30-watt OTL amp that does not like to see speaker loads below 7 ohms. The Stormbringers stay between 8 and 12.5 ohms above the pass impedance peaks, and don't dip below 8 ohms anywhere.

The NTV amplifier is a single-ended triode that uses an output tube called a "50" - I think the exact description is "UX-250 Power Triode". The "50" was rumored to have been RCA's counter to Western Electric's 300A and 300B telephone repeater tube. Out of production for decades, the 50s used at the show are new production from China. Richard Gray has purchased a large production run of 50s, which he and the Chinese designed together based on the best of the NOS tubes. Richard says that the Chinese 50s are pretty close to the best of the NOS tubes. I don't have enough experience with different tubes to comment on that claim. The NTV amplifier puts out 5 watts per channel.

Both of my speakers come in around 92 dB efficient and have similar impedance curves. As far as I know the Atma-Sphere room didn't have any clipping, but in the NTV room we did clip on loud piano passages a few times. So I think that 5 watts is probably borderline with either of my speakers.

Duke

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