@tomchr ... Thanks for making this device as it'll standardize all HP measurements worldwide. I hope the global HP audio community embraces your device as they've done with the APx instruments. May it be the next "it" device testers everywhere use to measure their devices. Amen and Amen!
Now, PLEASE, PLEASE, PLEASE (seriously!) ... can you make a reactive speaker load box, able to handle up to 1kW (or more) up to 8-Channels of amplification? This would handle stereo and all MCH amp types out there.
I have no doubt it will be a bit more expensive and even more challenging to design and build but we need a consistent reactive load device able to simulate the different types of speaker technologies on the market. Resistive loads are ok, but they don't stress the amplifier as much as a reactive load. As you well know, current/voltage are in phase with a resistive load but their relative frequency-dependent phase angles come into play once the load becomes reactive. This prevents the amp from providing rated power to the speaker, and depending on the reactive load, could cause the amplifier to oscillate. An amp could measure fine/superb with static loads but have serious trouble performing with complex reactive loads.
The following is a partial list of speaker load types out there, that your new box could test for:
1. Electrostatics (with their decreasing impedance with increasing frequency, up to 0.2 ohms at 20 kHz like the MartinLogan Spires I had for years). Examples are Martin-Logan and Quad Electroacoustics.
2. Purely resistive loads (Yes, that's right!) like most Magnepan speakers (4-ohms)... add in the obligatory low distortion 8, 4, and 2 ohms standard resistive loads.
3. Sealed enclosure and bass reflex loads with their resonance peaks (due to the woofers, mids, and tweeters) and their dips around their crossover regions.
You could make the new test box expandable, where for example, a user could parallel 2 boxes to handle 2kW amplifiers, 3 boxes to handle 3kW amplifiers, OR simulate loads for 16- channels amplifiers ... just an idea.
The box should be able to send its results to the APx that in turn calculates true amplifier distortion curves for a given reactive load. This truly can reveal an amplifier's true performance. I believe this will instill the fear of God in all amplifier designers as they see how their amps whimper terribly under the test.
BTW ... I foresee that marketing departments will hate you with a passion as they'll be forced to temper their often questionable and enthusiastic advertising claims quite a bit to match the amps' true measured performance
.
Thanks for listening!
Please note, 32 steps from 10 to 300ohm L/R independent and balanced/unbalanced 3.5/2.5mm supported. No cables to reduce residual rig impedance i.e. you can measure 50mOhm output and see .05ohm. Also possible to off all resistive load to use real headphones instead. $20 retail ))
