System Pictures & Description

[jleaman]

Originally posted by AJinFLA
Hi Simon,

I don't recall what they sounded like before the mods, since the sole purpose of buying them was for the unique cabinets. The drive units are not state of the art by any means, but are not junk either. The tweeter actually measured ruler flat (on axis), as flat if not flatter than the XT! Modified they actually sounded pretty good. I started with a D25AG35 back in '99, then changed to the XT as soon as it was available for DIY. On good recordings they would essentialy "disappear" the way a good speaker should. The XT-25 has a unique sound (if you have ever heard it) - very clear/clean, etc. There is a reason why it's used in so many designs. It's response plummets off-axis however. The rear tweeter was an attempt to even the power response, as well as add just a little "sparkle" to the high end. Placement out into the room was a must. But that forced me to use a higher XO to my sub than I would have preffered, since even though it has decent bass output, it's still a 5" driver. If you can pick up a pair in England for cheap, it might make for a fun project. Unfortunately that was my last "box". There's no going back now after these

You should post a picture of the whole system buy the looks of the room at that angle it should look awesome.

[AJinFLA]

Oops, I forgot to mention that I damped the interior with Cascade Kote Damping spray. Active XO's. I went all active a long time ago. Its DSP and OB from here on for this fellow.

Cheers

AJ

[SimontY]

Wow, looks like a beast of a system. You must be proud

And yet another person saying they can't go back after trying the open baffle thing...

[auplater]

Just completed these BG-75's as a dipole linesource, with Peerless HDS
mid-woofers for 600 Hz to 50 Hz range, Peerless tweeters (one firing forward, one backwards) from 3500Hz up, EAS-400 leaf-tweeter as super tweeter from 7000Hz up. The bottom end is augmented by a Titanic 12" sub in a 5 ft^3 sonotube, pretty much from 100 Hz to < 20 Hz.

The imaging is pretty dramatic, and the detail in the music is about the best I've heard in over 35 years of building and listening to loudspeakers. The baffles are handcut solid cherry 1" thick, the mid-woofer enclosures are 1" MDF.

Rough measurements are very smooth throughout the range 400 Hz - 16KHz, with SPL for system measuring > 107dB at 12 feet. (Everyone runs if I try to go higher)

[planet10]

Those look impressive... any non-coherency issues with the transitions from point source to line source & back again?

dave

[auplater]

Interesting you should ask. I originally thought about line sourcing with multiple tweeters (hence the extra baffle space) or additional mid woofers (still could be added if need be), but to keep the cost resonable, and being of the KISS (keep it simple stupid) mentality, I tried to minimize the drivers yet meet the power requirements.

The BG's are ~88 dB or so efficient; I initially connected the peerless tweeters in parallel facing forward ---> way too efficient for the BG's and suffered pretty severe comb-lobing within a few feet of the baffle.

Switching them to series connection reduced the output to compatible with the BG's, but comb effects still prevailed. I then reversed the top tweeter, connected out of phase (in phase with the BG's rear radiation), added Zobel networks on the drivers, added baffle step compensation @ ~220 Hz, added BG notch filter @ ~5500 Hz. (see attached photo of xover components not yet mounted)

The resultant sound is pretty seamless. My idea was to maximize the impact of the BG's , using the mid woofers to take over ~600 hz and down. They also are connected in series rather than parallel to better match the BG's sensitivity, and are mounted in a box tuned to ~50 Hz. The series connectiion is a much easier load to drive at high levels.

The front firing EAS 400 super-tweeter is a leaf type with minimal vertical dispersion, and curiously seems to have little audible interference with the peerless dome tweeter, maybe due to the much higher xover. The 45 degree swept wings help with rear wave directivity and seem to improve the general open dipole sound with wide and deep soundstage.

[Gmd]

Well finished both my speakers, very pleased with how they sound considering this was my first try.

http://gmd.shackspace.com/Speakers/SpeakersAmp.jpg

[maxw]

Originally posted by Gmd
Well finished both my speakers, very pleased with how they sound considering this was my first try.

http://gmd.shackspace.com/Speakers/SpeakersAmp.jpg

Nice
Was that a kit? or did you make and finish the enclosure your self?

[planet10]

Originally posted by Gmd
Well finished both my speakers, very pleased with how they sound considering this was my first try.

http://gmd.shackspace.com/Speakers/SpeakersAmp.jpg

Which Jolida is that?

dave

[planet10]

Originally posted by auplater
Interesting you should ask. I originally thought about line sourcing with multiple tweeters... with wide and deep soundstage.

Thanx for the detail... some good tidbits to store away for future reference.

dave