Hi Andrew, I have just checked the specs of your Tannoys here:
http://www.audiodigital.org.uk/reviews/hardware/second hand/tannoy/tannoy_wildcat_series.htm
Still looking for the B950, only boom stands!
How low and deep do you want to go? I don't think OB will do much better than the Leopard design. A t/l will reinforce down to 14 Hz if tuned to 28.
Another thought, not strictly OB. Baffles from floor to ceiling, outside edge against the wall. Inside edge adjusted to provide a port. 2 Tannoys a side.
Geoff.
http://www.audiodigital.org.uk/reviews/hardware/second hand/tannoy/tannoy_wildcat_series.htm
Still looking for the B950, only boom stands!
How low and deep do you want to go? I don't think OB will do much better than the Leopard design. A t/l will reinforce down to 14 Hz if tuned to 28.
Another thought, not strictly OB. Baffles from floor to ceiling, outside edge against the wall. Inside edge adjusted to provide a port. 2 Tannoys a side.
Geoff.
Hi Geoff,
The Leopards had seen hard use and have previously had new (wrong) surrounds fitted.
These too had suffered and all were split but the best of them had Fs=73Hz indicating a surround that was too stiff, it certainly felt it.
I have fitted foam surrounds and Fs=28Hz which I suspect is probably a little lower than the original. The 94db/w figure and the 35Hz from the spec indicate to me that this is a "light cone" model. I have a feeling that weighting the cone and altering the vented cabinet may be a solution, but the cabinets are not lounge friendly, so I am looking for alternative strategies to get low bass (20Hz or so).
These drivers may end up in the sub-bass horn, but that project is taking a lot longer than I planned.
The B950 is in almost perfect condition, but has an even higher sensitivity and Fs=43Hz. Should be good for very loud music but doubling up as a TV stand and for movie sound effects, it is a no goer.
The Leopards had seen hard use and have previously had new (wrong) surrounds fitted.
These too had suffered and all were split but the best of them had Fs=73Hz indicating a surround that was too stiff, it certainly felt it.
I have fitted foam surrounds and Fs=28Hz which I suspect is probably a little lower than the original. The 94db/w figure and the 35Hz from the spec indicate to me that this is a "light cone" model. I have a feeling that weighting the cone and altering the vented cabinet may be a solution, but the cabinets are not lounge friendly, so I am looking for alternative strategies to get low bass (20Hz or so).
These drivers may end up in the sub-bass horn, but that project is taking a lot longer than I planned.
The B950 is in almost perfect condition, but has an even higher sensitivity and Fs=43Hz. Should be good for very loud music but doubling up as a TV stand and for movie sound effects, it is a no goer.
I put my RCA console drivers on a baffle today.
And they sound really, really -- awful!
Yikes, they're horrible! No low end at all, and very shouty, strident mids. Oh well, they can't all be winners.
My guess is that the 12" is a strong magnet low Qts driver, so does not lend itself to OB very well. It may take massive amounts of active filtration to get it to a usable point.
The horn is pretty rough too. Turning it down or going to a 3rd order crossover helps, but not enough.
I have a couple of 10" drivers with a Qts of 0.62 that may sound a little better. Will have a try them on the baffle. Still don't know about that harsh Foster horn, tho....
And they sound really, really -- awful!
Yikes, they're horrible! No low end at all, and very shouty, strident mids. Oh well, they can't all be winners.
My guess is that the 12" is a strong magnet low Qts driver, so does not lend itself to OB very well. It may take massive amounts of active filtration to get it to a usable point.
The horn is pretty rough too. Turning it down or going to a 3rd order crossover helps, but not enough.
I have a couple of 10" drivers with a Qts of 0.62 that may sound a little better. Will have a try them on the baffle. Still don't know about that harsh Foster horn, tho....
Hi Michael, 1st up, what size are your baffles? 2ndly, how far back are you? They won't have much bass if you are on top of them.
Regarding magnet size. or lines in the gap, if you can see movement in the cone, you should be hearing bass, providing it's not being cancelled by a short baffle.
Another check is to place your ear a few inches from the cone, at low level. If you can hear the bass then, you have a phase cancellation problem. Wings etc will help that.
Merry Christmas to all, and your families.
Geoff.
Regarding magnet size. or lines in the gap, if you can see movement in the cone, you should be hearing bass, providing it's not being cancelled by a short baffle.
Another check is to place your ear a few inches from the cone, at low level. If you can hear the bass then, you have a phase cancellation problem. Wings etc will help that.
Merry Christmas to all, and your families.
Geoff.
Hi guys - and a "Mele Kalikimaka" to you!
I did try the suggested things. The driver is about 10 ohms (? 7.8 DCR) so tied all the way up to 9 ohms in series. Does help the bass a little, for sure.
Baffle is approx. 90x50 cm (35x20") with wings as large as 30 cm. The wings help for sure, but it is still very shouty, even with series resistance and a 1.5mH coil. All the above things do help, but the rig will need much more than that. Even went to a 3rd order x-over on the horn. Helped, but not enough.
Best results were with my Altec 811/806 on top, same crossover as the Foster. (~1500Hz, 2nd order). Muuuuch smoother. Pushed the baffle to within 30cm of the wall and put wings all around. A very leaky sealed box. Not great, but going in the right direction.
I suspect several things are going on.
The 12" has a too powerful magnet, thus no bass on OB.
The 12" probably has a nasty ~2K peak, as many do.
The Foster horn/driver sounds rough down that low. Need to move the attenuation before the crossover to help tame the peaks. A common horn problem.
I'll get back to work on these on Tuesday. Will keep you entertained with updates. Definitely NOT Plug and Play.
I did try the suggested things. The driver is about 10 ohms (? 7.8 DCR) so tied all the way up to 9 ohms in series. Does help the bass a little, for sure.
Baffle is approx. 90x50 cm (35x20") with wings as large as 30 cm. The wings help for sure, but it is still very shouty, even with series resistance and a 1.5mH coil. All the above things do help, but the rig will need much more than that. Even went to a 3rd order x-over on the horn. Helped, but not enough.
Best results were with my Altec 811/806 on top, same crossover as the Foster. (~1500Hz, 2nd order). Muuuuch smoother. Pushed the baffle to within 30cm of the wall and put wings all around. A very leaky sealed box. Not great, but going in the right direction.
I suspect several things are going on.
The 12" has a too powerful magnet, thus no bass on OB.
The 12" probably has a nasty ~2K peak, as many do.
The Foster horn/driver sounds rough down that low. Need to move the attenuation before the crossover to help tame the peaks. A common horn problem.
I'll get back to work on these on Tuesday. Will keep you entertained with updates. Definitely NOT Plug and Play.
Sounds like your having fun n games. Never did trust that plug'n'play!
(Linux does a better job)
I have mentioned this on other posts. When I took my Wharfies out of moth balls and into the corner cabs, I was somewhat disappointed. They seemed to be down 10db on the bookshelf Altecs they were replacing. And no bottom end. Almost like the coil was frozen in the gap. After an hour or so, the first one seemed to get better.
By the time I had the second cab built and in place, the first had come to life. After a couple of days of the 24/7, both channels had come up to what I expected.
I nearly canned the project. Glad I didn't. Your suspension may also be tight if they haven't been used for a while.
A layer of felt or polyester wadding over the back of the driver may help pull down the shout.
811's on top of an OB. Not the normal combination. But if we can get the bass up to scratch, why not.
Geoff
(Linux does a better job)
I have mentioned this on other posts. When I took my Wharfies out of moth balls and into the corner cabs, I was somewhat disappointed. They seemed to be down 10db on the bookshelf Altecs they were replacing. And no bottom end. Almost like the coil was frozen in the gap. After an hour or so, the first one seemed to get better.
By the time I had the second cab built and in place, the first had come to life. After a couple of days of the 24/7, both channels had come up to what I expected.
I nearly canned the project. Glad I didn't. Your suspension may also be tight if they haven't been used for a while.
A layer of felt or polyester wadding over the back of the driver may help pull down the shout.
811's on top of an OB. Not the normal combination. But if we can get the bass up to scratch, why not.
Geoff
Geoff H said:
Greets!
I assume you mean this pic: http://www.diyaudio.com/forums/attachment.php?s=&postid=1061894&stamp=1164070425
You're right, it's better than a pure round, but unfortunately not enough to be audible.
Yeah, I'm a big fan of oval FR drivers, all my early DIY horns used them, all 5" x 7" or 6" x 9" scavenged from radios, TVs, and junk cars.
GM
Hi GM,
You obviously survived Christmas.
Yep, that's the beast. Pity the guy that modified those Wharfies has passed away. I am seriously thinking of doing the same to the Alnico pair.
Back to the topic. Should we show Bob some real magnets. Like 10lb alnicos, or 18lb ceramic.
The old TV speakers were the pick of the bunch. Using a pot style magnet so as not to pull the picture, resulted in a very good magnetic cct.
I remember just how loud a tv with a 6x9" driven by a single 6BM8 or 6GV8 on the higher powered (4 watts!) especially when the tele was moved into the corner, with it's open back speaker chamber becoming a Klipshe.
Regards,
Geoff
You obviously survived Christmas.
Yep, that's the beast. Pity the guy that modified those Wharfies has passed away. I am seriously thinking of doing the same to the Alnico pair.
Back to the topic. Should we show Bob some real magnets. Like 10lb alnicos, or 18lb ceramic.
The old TV speakers were the pick of the bunch. Using a pot style magnet so as not to pull the picture, resulted in a very good magnetic cct.
I remember just how loud a tv with a 6x9" driven by a single 6BM8 or 6GV8 on the higher powered (4 watts!) especially when the tele was moved into the corner, with it's open back speaker chamber becoming a Klipshe.
Regards,
Geoff
WooHoo! Those would be some real weights for sure! Man,
What did they come out of? BTW, I am a step or 2 closer to completing the OBs, the smoke has cleared and I have all my appendages!! I have one of these that is just about here and I'm ready for a little single ended action.
Attachments
Geoff H said:
Greets!
Barely!
All in good time, all in good time......
The big AlNiCos spoiled me for life, but it's the big field coil systems I let go that haunt me........ 
Yeah, a corner loaded ~92 - 95 dB eff./Q = 1 oval 'FR' driver is a mini-force to be reckoned with. RadioShack 'kept the faith' until RCA took over and I managed to get really cheap on close-out some above average sounding 6" x 9" and 4" x 10" that do a fair job of mimicing a CD horn through the mids.
I have enough of each to build a 5 channel HT system of bipolar MLTLs, though the way my life keeps going, they may rot before I can make it happen. As it is, I have some NIB early 80s wide BW 8" Philips drivers that the foam surrounds have turned to a really nasty, sticky, goo. I'm not sure if these are salvageable since I don't see how to clean them without ruining the diaphragms. GM
Hi Bob, the 10 pounders are on Wharfedale Super 10 RSDDs. Many modern folk think you can't get good bass from a big magnet on a widerange. Mr Briggs knew different, otherwise he would not have had a long voice coil with 3/8" overhang. That's 10mm travel in each direction. I grew up with those, in 5 cub ft cabinets. They were my fathers, now my Daughters, and in my hands, 42 year old and still sound fine. My main system has a pair of 40 y/o, but modified to increase sensitivity, (104dB @ 1m-1w) and bring the resonance up a bit.
The 18 pounders are on my Altec Lansing 411-8As Another big displacer. I think though only 10mm total.
I think GM has some bigger units. about 22 pound on the 515s.
And yes, if alnico won't cut it, there's a mile of copper wire. And spiders with 3 "S" legs. No dust cap. What spider noise?
And the dust on 6V6s and 6SN7s, and the red and gold metallic finish on RF and IF tubes.
Cheers, Geoff.
edit: the spell check in firefox doesn't check grammar. And doesn't include firefox.
The 18 pounders are on my Altec Lansing 411-8As Another big displacer. I think though only 10mm total.
I think GM has some bigger units. about 22 pound on the 515s.
And yes, if alnico won't cut it, there's a mile of copper wire. And spiders with 3 "S" legs. No dust cap. What spider noise?
And the dust on 6V6s and 6SN7s, and the red and gold metallic finish on RF and IF tubes.
Cheers, Geoff.
edit: the spell check in firefox doesn't check grammar. And doesn't include firefox.
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