The Magpie-II is meant for listeners that want accuracy or a speaker for reference. For that, I tuned her for flat response. There’s no bass emphasis like in the previous Magpie.
Fig 1 – Black plot=SB17NRX2C35-4 RAW Response
The Blue plot in Fig 1 is the new measurement of the SB17NRX adjusted for a flat response. The midrange now sits just below the bass. This will rise slightly once I blend in the tweeter.
Fig 2 – Blue plot=SB17NRX2C35-4 Low Pass • Red plot=Seas 27TBFC High Pass
The Red plot in Fig 2 is the Seas 27TBFC tweeter crossing to the SB17NRX at 1.8kHz. What I like about this Magpie-II is I didn’t need to use any L-pad to attenuate the tweeter.
Fig 3 – Black plot=Magpie-II Passband
The Black plot in Fig 3 shows the passband of the crossover. The drivers actually sum very well. There is a touch of cancellations from 5kHz~7kHz caused by the cone breakup of the SB17NRX but it’s not serious. It’s not worth the expense to correct that but it can be done.if need be.
Fig 4 – Magpie-II Frequency Response
Fig 4 is the final frequency response of the Magpie-II. Overall, it’s very tight. From 600Hz~15kHz, it averages +2dB. Only at 5kHz~7kHz did it dip slightly.
Fig 5 – Magpie-II Null
Fig 5 is the null when I flipped the tweeter wires around. It looks similar to the Magpie but a bit better in that it’s more symmetrical. This is as good as being time-aligned.
Fig 6 – Magpie-II Spectrogram
The Step, Waterfall and Toneburst plots are similar to the Magpie so that’s no point in repeating them. It is in the Spectrogram that we can see some differences. The delayed hot spots around 2kHz are marginally stronger but as before, they soon dissipate by 6 msec.
Sound of Magpie-II
The Magpie-II is quite an unforgiving speaker. She will reveal what is in the recording. I heard things in some tracks which were not apparent in other speakers.
I can foresee another Magpie-II, this time for nearfield monitoring. Perhaps in a sealed box of about 18 liters. Slightly larger than the Yamaha NS-10M. I think it’ll work well.
Crossover is available on request. Free for DIY. Not for Commercial use.
January 28, 2021Projects