|With 24dB/oct electronic crossover
In this second test, a Peerless XT25TG30-04 is used in place of the budget BC25TG15. The XT25TG30 is one of the best tweeters in the $30 bracket. Unlike dome tweeters, the XT25TG30 uses a unique Dual Ring Radiator design. I honestly don’t know whether it’s due to this but it sounds really good.
In Fig 1, the Blue plot is the HiVi L6-4R and the Red is the XT25TG30, crossed at 2.6kHz (24dB/oct). The Black plot is the summed responsed. Overall, the response is quite respectable, within a 5dB window all the way to 15kHz.
What is interesting is when the tweeter reverts back to normal phase, we see a notch (Violet plot in Fig 2). Notice this notch is around the 2.6kHz mark. Not exactly spot on in Time Alignment but very close.
|With Synergy 18dB/oct Bi-amp Kit
In this test (Fig 3), a Synergy amp is used to power the woofer and tweeter. The Synergy has an 18dB/oct precision crossover which now replaces the 24dB/oct one. Synergy crossover frequency was set at 2.5kHz.
With the XT25TG30 wired in reversed phase (Fig 4), a notch appeared where the woofer and tweeter intersected. It is not as sharp as the 24dB/oct crossover but nonetheless, it’s still a fairly defined notch.
Notice how the phasing has changed. With a 24dB/oct crossover, the tweeter was wired in reversed phase for correct summing (Fig 1). With a 18dB/oct crossover, a reversed phase tweeter resulted in a notch (Fig 4).
|Which tweeter sounds better?
Without doubt, the XT25TG30-04 is the right tweeter for the L6-4R. The highs are clear and audible. What’s great with the XT25TG30 is that it has that finesse in the highs that expensive tweeters exhibit.
As for whether a 24dB/oct crossover sounds better than an 18dB/oct alternative, frankly, I can’t tell the difference. However, in terms of usage, the Synergy is extremely convenient. More importantly, the two LM3886TF Chip amps on board, together with the 18dB/oct crossover, sound great on music playback.
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September 8, 2017Projects