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tannoy cabinets question

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Posted on February 16, 2015 at 10:43:44
blinx7
Audiophile

Posts: 40
Joined: March 30, 2014
 Hi
Picked up a pair of generic bass-reflex cabinets on the weekend, hoping to install my tannoy 12" golds.

These are pretty sizeable and used to house a (mismatched) pair of wharfedale 10" drivers. With the plywood flats that resized them for the Wharfdales removed, the driver opening looks to be a perfect fit for the tannoy 12s.

Got a problem, though, and wonder if you can help:

These cabinets look pretty identical. They look in fact like the old Barzilay type of supply-your-own-drivers hifi speaker from the department store or furniture shop back in the day.

But as for internal build and in measurements, like maybe they're from slightly different eras, though most differences are small/ vague. You can't tell from looking at the externals, but if you measure ....

The port sizes are different. One of the cabs has a 10½ x4" reflex port, and the other has a 10½ x 5" port. With the idea of housing Monitor Gold 12s (both enclosure interiors are 22½w x 28½h x 13½" deep)-- is EITHER ONE of these port configurations right for the tannoy twelves ?

Ports are a flat cut-out, rectangular in shape, 6½" below driver cutout.
Thanks for the advice, I seem to get lost with those online automated cab-port sims.



 

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RE: tannoy cabinets question, posted on February 16, 2015 at 14:05:28
Chef Henry
Audiophile

Posts: 367
Joined: July 27, 2001
 Those sims presuppose that your speakers' measured response is close to the original published ones, which is highly unlikely. After all this time, it would be surprising if your Golds even measured the same with respect to each other.

Under certain circumstances, it may actually be advantageous to tune each cabinet to a slightly different frequency, on the theory that by spreading out the resonance, the speakers will be less likely to excite room modes, resulting a smoother response.

You can also try closing up both ports to create sealed systems, or what in those benighted times we referred to as infinite baffles. In the Olden Days, many Tannoy enthusiasts, especially those with a preference for symphony and opera, preferred sealed cabinets. Closing the ports will raise the system resonance, but the rolloff will be more gradual, and the bass will be tighter, and possibly more natural. All it would take to try it is two pieces of scrap lumber.

 

cabinets question, posted on February 16, 2015 at 19:38:20
bare
Audiophile

Posts: 1879
Joined: April 14, 2009
 Small Reality dose :-)
Enclosures only affect frequencies below 200hz.
Tuning / appropriate enclosure sizes affect low frequencies.
The better tailored the design, the deeper one can obtain palpable results. Even roughly approximate 'boxes' will do surprisingly well... likely hitting FS (at ~46 hz).
Tannoy MG 12's go pretty darn deep.. even when in a suitably sized cardboard box.
Yes I've tried it.. on a whim.
That said: Those Do deserve a bespoke box.
Just how crappy Are those salvaged boxes.. where one varies from the other ??
Buy / build appropriate boxes.. or if it's problematic, sell the drivers on :-) paraphrasing Ettore Bugatti: when a customer complained that his car wouldn't start after spending the night outdoors.

 

RE: question, posted on February 16, 2015 at 19:51:30
blinx7
Audiophile

Posts: 40
Joined: March 30, 2014
 Agree with everything said.

But that doesn't get me off the starting line. Yes, someday maybe Cornetta boxes from a cabinet maker. Between here and there, I'll start with these. Maybe I talked them down too much. They look like orig-tannoy Belvedere cabs, but- they're not. Like as not they're from some standard american furniture makers in late 5os early 6os. Nice walnut veneers, tight joints, no potted-plant rings on the tops. Workable.

What I need to be knowing is whether that 4" port dimension is better or worse than the 5" port dimension. So I can match the other one to it, and at least start myself out with a level playing field...

*edit: make that tannoy Belvedere Senior; v.similar to the 32x24x16 external size of these generics.

 

RE: question, posted on February 16, 2015 at 22:04:38
Paul Joppa
Industry Professional

Posts: 7295
Location: Seattle, WA
Joined: April 23, 2001
 If you have the Thiele-Small parameters for the drivers, and the cabinet measured volumes, then you or most of the people here can run some free software and answer the question. If you don't have those data, no calculated answer is possible - leaving you to listen and decide subjectively for yourself.

 

Tannoy Thiele & Small Parameters, posted on February 17, 2015 at 05:53:13
RayP
Audiophile

Posts: 727
Location: Maryland
Joined: June 30, 2005
 See link.

The web site also has numerous examples of cabinets.

ray

 

RE: tannoy cabinets , posted on February 17, 2015 at 07:36:49
blinx7
Audiophile

Posts: 40
Joined: March 30, 2014
 Allow me to confess my ignorance here, then.
While I get the notion of an online calculator, etc, I'm not on home turf with the whole T&S group of data. I'm fairly unknowledgeable about all this and don't want something obvious to the experts to send me doing a larger cutout or whatever -- in error.

My boxes are 22.5w, 28.5h, 13.5"deep, internal measurements. The specs re T&S are at the link below.

Question is, just to reiterate-- my cabs right now have two differing port cutouts-- one is 10.5 by 4 inches, the other is 10.5 by 5 inches... Is either of these the correct one for the tannoy gold ? Failing that, is either one of these close, and close enough for (what I think are 5.o cubic-foot) pretty large boxes ?

Just looking for someone who might glance over this and be able to advise. Thanks for responses.

 

RE: tannoy cabinets, posted on February 17, 2015 at 08:48:59
blinx7
Audiophile

Posts: 40
Joined: March 30, 2014
 If all else fails, I might just end up, as you propose, sealing up the ports to see whether that seems like an appropriate thing.

"Closing the ports will raise the system resonance, but the rolloff will be more gradual, and the bass will be tighter, and possibly more natural."

What's the downside of 'raising the system resonance' ? Gradual rolloff, tighter bass, that all sounds like advantage. Will the bass be diminished, but what remains is tighter ?

Like everything in audio I'm guessing there's a tradeoff, but not sure I'm getting the basic deal here..

thanks

 

RE: tannoy cabinets, posted on February 17, 2015 at 10:46:28
Chef Henry
Audiophile

Posts: 367
Joined: July 27, 2001
 Low tech, perhaps, but undeniably scientific: Place your speakers next to each other. Pick out several of your favorite recordings. Set your preamp's selector switch to mono.

Enlist a friend to turn the balance control back and forth, from the right to the left, then back again until you have decided which port size sounds best.

Next, seal up the port of the less-liked speaker, and repeat the process until you have determined your preference, ended the friendship, or both. Welcome to the Asylum.

 

RE: tannoy cabinets, posted on February 17, 2015 at 14:35:34
blinx7
Audiophile

Posts: 40
Joined: March 30, 2014
 good post; and yes a good way to get rid of friends / wives whoever...

Undeniably scientific? Well, certainly some kind of scientific.
The problem arises where neither of the port sizes I have are anywhere near correct. At that point all the a/b comparisons in the world won't really add up.

Hopefully though, T&S-based "you need x-dimension ports" info would settle it with more authority.
Experts ?

 

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