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Old

Musical monitor: Some comments on the positive input in the original thread

Posted 7th July 2012 at 04:45 AM by fas42
Updated 16th July 2012 at 12:21 AM by fas42

By tnargs:

Quote:
I was assuming we were going to take something like a Behringer 2031A (2 way, 8", active, affordable) and see what tweaks are on the table.
Most perceptive ...

Quote:
Whenever I see a measured FR of a Behringer it looks nice and smooth and flat, off axis too, so it seems a decent start.
Exactly so.

Quote:
Although Lynno's post is true enough, I thought we would be keeping the drivers and looking at any gains from astute use of felt or resin (on or around the cone/dome), replacement of dust cap, stiffening or dampening the pressed steel driver frame... what else?
Possibly will improve the frame in some such fashion; and look at stronger coupling of the whole driver assembly to the carcase such that vibration is transferred in the most direct path to the surface the monitor is sitting on.

But these things will be only addressed after the electronics are sorted out, and I see how well the driver behaves itself at maximum SPLs.
...
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Old

B-board Boxer Project : A Low Voltage Headphone Amplifier for 16 ohm Loads

Posted 7th July 2012 at 12:19 AM by rjm
Updated 29th September 2012 at 02:58 AM by rjm

I always seem to end up optimizing my headphone amplifier circuits for higher impedance headphones, this mostly happens because I own a pair of 300 ohm HD-600s and it is tedious to design for both the voltage requirements of high impedance headphones and the current requirements of low impedance headphones.

Not impossible, just, for the class-A designs I seem to be building recently, increasingly large, heavy, and impractical.

Complimentary transistor circuits, however, offer the opportunity to swap voltage for current at something close to the same design cost. They are therefore a practical topology for efficient class-A power delivery into low impedance headphones. As a design experiment, my aim is to discover how far I can leverage an ultra-low-voltage, unity gain circuit for compactness without sacrificing sound quality.

Ok. Back-of-the-envelope calculations:

A typical 16 ohm in-ear-headphone has a sensitivity of 100-105...
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