Bigger than most and the largest Dual Concentri I've worked on: the BTH K10A.
18" bass cone, long DC tweeter with twin mouth flares, these were used in cinema installs pretty widely. Lots of info and history here.
retro vintage modern hi-fi: The BTH K10A
So a company capable of building locomotives and all associated things, does a deal to use Western electric 18 DC baskets and makes them using alinco magnets for cinema installs. High budget and top quality are very important...
The result is exceptionally well designed and engineered drivers and X/O's...
Driver from front
Driver from rear
Actual driver ready to install.
Ok so what cabs...
I designed an upscaled GRF-R cab along these lines. Modelled the back loaded horn in hornresp to sim gettig it right
Cut wood - 21 and 24mm Scandi birch ply.
Build in progress
Tear drop for the throat as discussed on Tannoy forum to reduce/prevent HF going down the horn - as does lots of felt.
Pair of cabs (these will weigh in at around 100KG's each
Choice of finishes on tester
Actual finish chosen on another tester - mahogany stain and deep mahogangy finishing wax, was the top one.
Testing a driver with the BTH 2nd order original crossover
Crossover box finished (will be kept behind or on top of speaker).
Used 4 pole neutrik / speakons for easy connecting up and positive action, sockets and plugs from the X/O to speaker cabinet and another set for the driver to cab for easy install / servicing removal later if ever needed.
Plot of the woofer measured at listening spot
Plot at 1m from driver centre - blue line is once I phased the HF right, red line with it wrong.
Testing proved a big, capable, room filling sound! Deep bass and fine tonal balance and bass detail from the 18" cone and horn HF. The X/O is at 1700Hz, which seems high but BTH knew what they were doing and it sounds powerful/clearer/dynamic and more like my multi way horn system than Tannoys I've built / listened to do. Real voice of the theatre stuff.
Grilles complete and test placed for photo
Fitted properly
So a really interesting big project. I hope you enjoy reading about these rare and very good sounding drivers in a GRF-R style cab.
18" bass cone, long DC tweeter with twin mouth flares, these were used in cinema installs pretty widely. Lots of info and history here.
retro vintage modern hi-fi: The BTH K10A
So a company capable of building locomotives and all associated things, does a deal to use Western electric 18 DC baskets and makes them using alinco magnets for cinema installs. High budget and top quality are very important...
The result is exceptionally well designed and engineered drivers and X/O's...
Driver from front
Driver from rear
Actual driver ready to install.
Ok so what cabs...
I designed an upscaled GRF-R cab along these lines. Modelled the back loaded horn in hornresp to sim gettig it right
Cut wood - 21 and 24mm Scandi birch ply.
Build in progress
Tear drop for the throat as discussed on Tannoy forum to reduce/prevent HF going down the horn - as does lots of felt.
Pair of cabs (these will weigh in at around 100KG's each
Choice of finishes on tester
Actual finish chosen on another tester - mahogany stain and deep mahogangy finishing wax, was the top one.
Testing a driver with the BTH 2nd order original crossover
Crossover box finished (will be kept behind or on top of speaker).
Used 4 pole neutrik / speakons for easy connecting up and positive action, sockets and plugs from the X/O to speaker cabinet and another set for the driver to cab for easy install / servicing removal later if ever needed.
Plot of the woofer measured at listening spot
Plot at 1m from driver centre - blue line is once I phased the HF right, red line with it wrong.
Testing proved a big, capable, room filling sound! Deep bass and fine tonal balance and bass detail from the 18" cone and horn HF. The X/O is at 1700Hz, which seems high but BTH knew what they were doing and it sounds powerful/clearer/dynamic and more like my multi way horn system than Tannoys I've built / listened to do. Real voice of the theatre stuff.
Grilles complete and test placed for photo
Fitted properly
So a really interesting big project. I hope you enjoy reading about these rare and very good sounding drivers in a GRF-R style cab.
Last edited:
Very nice. They seem so be a rare driver indeed, cherish them!
I'm fairly certain from the measured response that HF would be missing for me, how do you find the actual performance? Feel like a super-tweeter would be needed or it's fine like that?
IG
I'm fairly certain from the measured response that HF would be missing for me, how do you find the actual performance? Feel like a super-tweeter would be needed or it's fine like that?
IG
They perform much like Tannoy DC's on the top end. Perhaps a little better. Many do not bother with super tweeters but some do. I put my Raal Lazy ribbons atop a pair of Tannoys and measured them and yes, they can be tweaked to fill in the trail off.
They are 1/3 octave. I have used 1/6 at times but 1/3 gives enough of a trend.
Here they are full screen width which make them look more smoothed than a smaller screen width but of course they have the same data.
I've found +/-5dB in room on 1/3 to be a good indicator of being on the right track
The K10A's are now back home with me resplendent in the new cabinets that Steve built. The quality of finish on the cabinets is superb.
I the last couple of days I've probably played every genre of music through them and if one thing stands out it's the effortless ease that music just flows from them. There is no bass boom or thump, just very a natural, realistic presentation of instruments and vocals. The adaption of a scaled up GRF design really works. The HF integrates well with the LF and I have never found K10A's to be lacking in HF extension or detail.
Steve's pics don't convey how large these cabinets really are. This is the K10A's together with my Westrex 2626A's and JBL Array 1400's. The JBL's look tiny by comparison.
I the last couple of days I've probably played every genre of music through them and if one thing stands out it's the effortless ease that music just flows from them. There is no bass boom or thump, just very a natural, realistic presentation of instruments and vocals. The adaption of a scaled up GRF design really works. The HF integrates well with the LF and I have never found K10A's to be lacking in HF extension or detail.
Steve's pics don't convey how large these cabinets really are. This is the K10A's together with my Westrex 2626A's and JBL Array 1400's. The JBL's look tiny by comparison.
- Status
- Not open for further replies.