This 2K6 version pushes the SuperMicro2 to the limit. Instead of crossing at 3.5kHz, I decided to cross the Peerless BC25SC08 at 2.6kHz. The aim is to get the midrange to be more prominent.
Peerless BC25SC08-04 Frequency Response
Fig 1 – Black plot = RAW. Blue plot = 2.6kHz. Red plot = 2.6kHz+10Ω. Brown plot = 2.6kHz+47Ω
The Black plot in Fig 1 is the RAW response of the BC25SC08. This is without any crossover. The short horn cut off frequency is about 1.8kHz. The slope after roll-off is quite linear.
The Blue plot is the BC25SC08 crossed at 2.6kHz (24dB/oct). It exhibits a beautiful, rounded knee followed by a very linear slope The Red is with a 10Ω resistor in series while the Brown is with a 47Ω. I had to resort to passively padding down the tweeter’s sensitivity because even with my electronic crossover gain control at minimum, I still couldn’t lower the sensitivity to match the FE85.
What is interesting is with a 10Ω resistor, the roll-off knee is affected. Note how sharp it is at 2kHz. With a 47Ω, it’s even worse. This will obviously affect the crossover. Out of convenience, I shall use the 2.6kHz with a 10Ω resistor in series. It’s not perfect but I am anxious to hear whether lowering the crossover frequency to 2.6kHz will make a huge difference.
Fountek FE85 with Peerless BC25SC08-04
Fig 2 – Frequency Response of FE85 and BC25SC at 2.6kHz (24dB/oct)
Fig 3 – Frequency Response of FE85 and BC25SC at 3.5kHz (24dB/oct)
Fig 2 is the FE85 and the BC25SC crossed at 2.6kHz (24dB/oct). The two drivers cross acoustically at 2.5kHz. The plots in Fig 3 are of the SuperMicro2 where they cross at 3.5kHz.
SuperMicro2K6 Frequency Response
Fig 4 – Summed Response of FE85 and BC25SC at 2.6kHz (24dB/oct)
Fig 4 shows the SuperMicro2K6 frequency response. There is a slight bump at 2kHz, followed by a tapering off at 4kHz. Apart from that, it looks the same as the previous SuperMicro2.
Is there a difference
Yes, definitely so. As I had hoped, lowering the crossover frequency brought the midrange forward. The SuperMicro2K6 sounds like you’re sitting near the stage whereas with the SuperMicro2, it was farther back.
When I integrated the SuperMicro2K6 with the Toucan Bandpass subwoofer, I was pleasantly surprised. The midbass (80Hz~200Hz) of the Toucan thickened up. The bass notes sounded stronger and fuller. Somehow, lowering the tweeter crossover to 2.6kHz affects the bass.
The SuperMicro2K6 with the Toucan Bandpass Sub exceeded my expectations. You won’t need to strain your ears for the midrange. The clarity and transparency is there. Top it off with a full bodied bass, it’s amazing I got this level of performance with cheap drivers. This is one system I can live with.
Note: All measurements were made with the mic at 1m, tweeter axis. Impulse Window=5ms. No smoothing applied.
December 31, 2018Projects