Might be of interest to people who measure their financial resources by the wheelbarrow.

• http://www.passlabs.com/pdf/rushmore.pdf

when companys start 'back in the day ,when audiophiles had 10watts.' you know its gona be 'one of those pdfs' ;-)

the efficient approach is a different one-i like it

Class A :-)

But it seems like the main idea was 'nice sound' not necessarily low distortion.

Having only two stages, these amplifiers embody the audiophile quest for the most realistic sound through minimalism and purity of signal path. Single-ended Class A amplifiers have what is known as a monotonic character; they continue to improve as the power level goes down.

thats debatable.but a shorter signal path can be good.

I do agree for sure,at low power much more better.

The high mass of the cone results in slow attack and decay response to impulses from the amplifier, but this has been considered an acceptable trade off.

This just means the speaker has a lower top end usable frequency limit.

It will appeal to many retro audiophiles that like the classic gear :-D

il stick to my 1600$ all horn system plans :-)

Cheers!
mike.e

There are some obvious mistakes:
"The filter characteristics for each driver are determined in passive filter networks prior to each of the four amplifier inputs per speaker....For best transient and phase response, the mid-bass and mid-range band-pass filters are single-pole types, while the bass driver sees a 2 pole low pass filter at 22 Hz and the ribbon tweeter is crossed with 2 poles at 8 KHz. None of these filters uses feedback, positive or negative."
22Hz Low pass?????????? Does this mean the 98dB/W@1M 10" goes down to 22Hz? I don't think so, Tim! (220Hz seems more likely a choice for X-over freq. from a 15 {2P} to a 10 {1P}.)
Feedback in a passive filter?????????? NOT POSSIBLE!
Other than these quibbles it's an interesting read with minimized marketing hype.

• Sancho and Pancho