If I had a second livingroom - or a dedicated hifi-room, these panels would be there. View pics below. The JA8008/TW034 combo helped by the 15" Eminence bass drivers will probably never come closer to projecting a live feeling. In that respect they even beat the DTQWT by a small margin. But... it comes at a price, a serious price: Panel size, a suitable room, an electronic crossover + extra amps - and not least ultra-low WAF.
Whether your room can accommodate these panels is the first thing to consider. 20 square meters is probably minimum for these speakers to breathe properly and if your room does not allow for experimentation with placement, look elsewhere. Our livingroom is 24 m^2 and the panels were placed on the longest wall. As discussed in the OB7 file, a more optimal placement would probably be like this:

What's seen above to the right is well on accordance with Gilbert Briggs' recommendation for the SFB - way back in the Fifties.

What I almost hate to admit is the quality of the sound coming from the JA8008/TW034 combo after passing countless operational amplifires in the dbx electronic crossover + not to forget some off-the-shelf interconnects. No wonder professionals sometimes shake their heads hearing NFB triode nerds praising their trade.

Before getting into details, here's the recipe:

- 1 x JA8008/TW034 kit (= a pair), available from Jantzen Audio, mail for quotation here.
- 2 x Eminence Deltalite II 2515 bass drivers, available from here.
- 1 x electronic crossover, 24 dB L/R with variable point of crossover
- 2 x stereo power amps, anything from 20 watts and up will do. Small SET amps can easily run the mid/tweeter section.
- A decent clone of the beautiful vintage Wharfedale SFB speaker.
- Liniarise Deltalite II impedance from 15 uF + 10 ohms across terminals.
- Add baffle step loss compensation to the bass drivers from 8.2 mH bypassed by 4.7 ohms.
- Hook it all up, set point of crossover between 80 Hz and 160 Hz to your liking.
- Make coffee from freshly ground Arabica beans, pour a decent cognac, sit down in your favourite chair and enjoy the concert!

After numerous experiments with passive crossovers between bass and mid drivers, I gave it up. Having a pro dbx 223XL, Stereo 2-way/Mono 3-way 24 dB, L/R electronic crossover, I inserted this between bass and mid and set the point of crossover at 80-120 Hz.
The 4th order electronic crossover makes a smooth transition between bass and mid and I suggest point of crossover at 120 Hz, but take your time and try vocal recordings @ 80-100-120-140 Hz and make your choice. Going higher draws vocals towards the floor and it starts sounding a bit funny.
Some other time I'll get the passive crossover in place. I want it simple, but this ECN set-up works darn well.

The current set-up makes a really big speaker and and it can play immensely loud with low distortion, so take care of your hearing!
There's an excellent live feeling to the presentation and I won't hesitate to recommend the current system for main speakers in recording studios, built into the walls in front of the all the mixing gear. With 220 liter cabs to the Eminence drivers and a port tuning of 32-35 Hz we will have response down to around 30 Hz. The 8008/TW034 could do with 25-30 liters. Well, another project....

Those who do open baffle studies may wonder why a relatively low-Qt (0.38) bass driver was chosen here. The Eminence 2515 will produce some 97-98 dB/2.8 volts and I simply wanted some extra sensitivity to play around with, and it's easy to tune the bass driver down to 94-95 dB, which is needed to match the 8008 driver. The Deltalite has a speedy and punchy bass response and from my OB7 baffle the main problem is identifying all the things in your room that starts rattling! What the Deltalite does on this baffle is making the music not only emotional, but also physical. Upright bass players will love the sound from these panels. Two 15" drivers hardly move driven even to very loud levels, i.e. distortion is as low as can be.