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Loudspeaker Designs and Articles for the DIY Enthusiast
Jim Holtz's:
Finalists

Big sound from a monitor sized
speaker design using high
value drivers.
Links to:

Main / Design Goals

Driver Selection

Cabinet Construction

Crossover Design

Measurements

Listening Impressions
Measurements:

Curt:
Part of my design regimen is to measure the HD of every driver in hopes of minimizing the effects of driver distortion by careful selection of crossover
points. With the RS225, NE149, and RS28F, there were simply no significant distortion artifacts to consider. Where a typical driver might have a spike or two
at some frequency, here we have HD plots remarkable only in their lack of issues. The RS225-4 exhibited THD in the low tenths of a percent, and that was
predominately 2nd harmonic.
The NE149 is also excellent, with THD only rising to above 1% below 150 Hz, likely due to the increased excursion at those frequencies. Again
predominately 2nd harmonic, with the higher harmonics far down into the noise floor.
The RS28F is well known for its excellent distortion characteristics.
Below is an independent in-room response measurement with the enclosure 24 inches from the front wall. Props to Todd Premo for sharing his time and
measurement skills. His in room measurement shows excellent correlation to the modeled response even when measured in a different setting.
Lastly, a horizontal response plot derived from measurements made every 15 degrees up to 90 degrees, showing excellent directivity up to the point where
the tweeter starts beaming.