Low Pass Filter Response
The Black plot in Fig 1 is the RAW response of the ER18RNX. The Blue plot is with a Low Pass filter. No smoothing is applied. Due to room limitations, measurements below 500Hz are in Nearfield.
Crossing over to the 27FDFC tweeter
The Red plot in Fig 2 is the response of the Seas 27TDFC with the High Pass filter. The response is not as smooth as it can be but it’ll look better once I flush mount the tweeter.
Starling-TA Time Aligned Frequency Response
Fig 3 is the Time Aligned Frequency Response of the Starling-TA. Most obvious is a +3dB bump at 4kHz. I can correct it for a flat response but I will have to compromise a bit of the Time-Alignment which I’m not prepared to do.
Starling-TA Reversed Null Response
The Violet plot in Fig 4 is with the 27TDFC tweeter wired in Reversed Phase. A -45dB sharp null is produced with the tip at about 3.2kHz. This is a solid Time Alignment of the ER18RNX and the 27TDFC.
Starling-TA Harmonic Distortion
The Starling-TA harmonic distortion in Fig 5 is about -55dB below the fundamental. From 500Hz to 10kHz, the 2nd and 3rd harmonic distortions are very linear.
Fig 6 – Starling-TA Impedance
The Starling-TA is an easy load for power amplifiers. The lowest is just below 5 Ω at 7kHz. The majority of amplifiers will not have any issues with it.
Electrical phase is well behaved. From 10Hz to 20kHz, it doesn’t deviate by more than +/- 40°. This is particularly important below 100Hz as more energy is demanded for bass.
Auditioning the Starling-TA
This speaker is for vocal lovers. Nothing comes close. Female voices in particular, sound scarily real and intimate. When I heard “Anyone But You” from Jewel “Perfectly Clear” Album, the loneliness and pain suffered in separation stabbed my heart. It was so clear I could make out the close miking and a tinge of her breathing. Amazing.
The icing on the cake with this Starling is obviously in the Time Alignment. Due to the time alignment of the ER18RNX with the 27TDFC, the sibilance is extremely accurate. You will hear it exactly as what is in the recording.
Speakers which are not time aligned have phasing issues which can clearly be heard in the sibilance. The sibilance sounds elongated, like two “ssssh ….. sssh” and often sounds harsh. You won’t get that with my time-aligned speakers.
As for the +3dB bump at 4kHz, I was surprised I did not hear any issues on playback. Normally, in non-time aligned speakers, a +3dB bump at 4kHz is cause for concern. The speaker will sound a bit bright and hard. However, with the Starling-TA, it was nothing of that sort. The music came out smooth. Perhaps it has to do with the time alignment.
Crossover Values & Box Dimensions
If you’re interested to build this project, kindly send me a mail for the crossover and box dimensions. For non-commercial use only.
November 19, 2017Projects