I see that the HT-88 has made an appearance on the DIYsoundgroup page. Matt Grant, can you give us a breakdown of it's design and what potential customers should know about it? Thanks!
The HT-88 is an MTM design using a pair of 16 ohm variants of the Celestion TF0818 from the HT-8. It uses the square SEOS-77 waveguide which has a 70x70 dispersion pattern. It uses a new compression driver which is looks like a ferrite version of the CDX1-1730. This compression driver allows for a much lower crossover point without distortion becoming a problem. Basically this is for those of you that want a speaker with the performance of the HT line that can be used as LCR and if needed used horizontally for the center channel with only 10" of height. Since it is a two way MTM it has the limitations most MTM's do with more limited dispersion on it's long axis. The low crossover the new compression helps achieve (~1250Hz) does allow for approximately 30 degrees of coverage (+-15 degrees to -6dB) when the speaker is used horizontally before encountering cancellation between the woofers. This is enough for most 2-3 seat sofas or couches at 10 foot listening distance. Output capability of the pair of 8" woofers will be similar to the 12" in the HT-12. In comparison with the 88-Special which also uses the same woofers and compression driver with the SEOS-15 mounted above the pair woofers: The 88-special has higher efficiency (~97dB) but the bass rolls off sooner, the HT-88 is a little less efficient (~93-94dB) but with a little flatter or more full sounding bass response. Used as a center channel the 88-Special will give wider horizontal dispersion (~60 degrees near the crossover, about double that of the the HT-88) due to the closer woofer spacing and the larger SEOS-15 allowing for an even lower crossover point. But the 88-Special is obviously much taller with the waveguide mounted above the woofers.