170GOLD LEAP Design Special: HM170C0x2 and TW025A28 MTM Pair

LEAP Design Special 170GOLD: HM170C0x2 and TW025A28 MTM

This package includes four woofers, two tweeters, and two fully assembled premium crossovers, with 10% off the drivers.

• Configuration: (2) HM170C0 6.5" woofers and TW025A28 1" dome tweeter MTM
• Box Size: .4 cf3 sealed
• SPL: 92 dB
• Impedance: 4 ohm
• Frequency Response: 42Hz to 20kHz
• Nominal Power Rating: 120 watts

We have culled our Crossover Design Library for the most promising crossover simulations. We are putting these together as a package deal for folks who want to experiment. These designs were custom-generated by Madisound's very experienced engineer who sadly passed away in recent years, so this is sort of in his honor. (He did hundreds of designs over the years, so he knew what he was doing!)

This design uses two HM170C0 6.5" Audax Carbon Fiber cone mid-bass drivers in parallel combined with the Audax TW025A28 gold dome tweeter in a MTM configuration in a small sealed box 0.4 cf3.

You will notice bass output on the lower region of the woofer response is bumped up a bit. This is due to LEAP simulating frequencies below around 200 Hz in half space (this means the speaker is radiating just 180 degrees when measured, i.e. half a sphere). This results in a frequency response with higher output in the bass section sloping gently to the midrange/tweeter. This blends the drivers most naturally to our ears in our experience. The output of the loudspeaker after the crossover is applied is mostly the decibel level between 200Hz to 800Hz on your graph (lower midrange region). 

On this design, the crossover point is at right about 2 kHz. High output 90dB+ range. Two hi-pass caps including a large value 20mfd. -0- zero value on series resistor on high pass, this can be adjusted to taste for tweeter padding. Impedance mostly 4 ohm.

Unless otherwise requested, for optimal parts spacing crossovers will be assembled on one 5.5" X 5.625" Matrix and one 5.5" x 3.75" 64B board per channel. These boards are tin plated copper on fiberglass. The 64B can take 0.25" solder tabs or quick connector receptacles, but the Matrix board has solder pads only. The crossovers will be fully assembled with SideWinder 16awg air core inductor and MDL cap in low pass and with Solen film caps and Mundorf Metal oxide resistors on tweeter. Since the box is so small you might consider running them externally.

For this design, we recommend a sealed box of 0.4 cubic feet. Sample external dimensions 20" x 8" x 8" stuffed and sealed.






Frequency Response- individual: The graph above shows the output in SPL across the frequency range. The left-most line is the woofer and the right designates tweeter. The crossover "point" is at about 2kHz.




Frequency Response- summed: The graph above shows the summed frequency response. Nominal output is in the lower 90's dB region. Very efficient nominal 92 dB.




This graph shows the system impedance. Mostly 4 ohm across the midband.

Basic Assembly Instructions

1. If using cabinets not pre-cut for your drivers, mark the enclosures for pilot holes and drill pilot holes.
2. Cut internal wires to appropriate lengths. Adjust according to the cable type you are using and solder wires to crossovers, observing polarity.
3. Install crossovers inside cabinet. We recommend a double stick tape to adhere to the cabinet base.
4. Solder input leads to terminal cup, observing polarity, and install terminal cups.
5. Cut and install desired insulation materials. Typically you would cut a slit in the foam, then pull the drivers' lead wires out through their respective driver holes.
6. Separate and fluff-out fill material such as Acousta-Stuf then place in cabinet, dispersing evenly throughout the main cavity and apply gasketing tape material to cutout holes if desired.
7. Solder wires to drivers, observing polarity.
8. Align drivers with pilot holes and secure with wood screws or desired fasteners. Tighten slowly and evenly.
9. Double-check polarity. If woofer polarity is incorrect, the loudspeaker will typically have weak or poor bass response. If tweeter polarity is incorrect, the system may have a dip in response in the midrange and sound odd.

The Audax TW025A28 is a gold-plated titanium dome tweeter with smooth, clean and effortless sound.

See more free designs in Madisound's Crossover Design Library!