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Need Help: Designing 12" Tannoy + 15" Woof
Need Help: Designing 12" Tannoy + 15" Woof
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Old 29th October 2019, 04:51 PM   #1
KrautNotRice is offline KrautNotRice  United States
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Default Need Help: Designing 12" Tannoy + 15" Woof

Hello fellow hifi fanatics and tinkerers.
I've found myself yet again needing to build cabs from scratch for a set of dual concentric drivers that I like the mid-bass, mids and highs of.
I picked up a pair of Tannoy CMS 1201 DCT 12" dual concentrics, brand new, paper cone with very stiff suspension, 1.34" aluminum dome firing through the hole in the woofer with a phase plug.
The driver model # is 1276 and there seems NO info or specs on this at all, except that the manufacturer rates the -3 db for the woofer at 60 hz, that's presumably mounted in their 2.9 cf ported back can which I do not have.

So my first thought was to build large cabs around 5 cf and see how low they can go, but with a little bit of researching I've found that the predecessor to my ceiling speakers are CMS 12/8 and apparently their woofer fs is around 60 hz, so no point really trying to get any low bass out of these. This is that thread:
12" tannoy paper coax and box type. Karlsonator or...?.

I've sorta settled on using a 15" helper woofer at this point.
My main question is: If I use one Dayton PA380 per cab at 93 db efficiency, passively low-passed, will the speakers still be 'easy to drive' and can a small amp or tube amp still power them with ease like right now?

The CMS 1201 are 97 db efficient, so close enough to the Dayton PA 380's 93 db. I'm worried that passively low passing the helper woofer, say around 150 hz or so, will introduce a phase cancellation around the crossover point. Is that possible to avoid without an electronic crossover and bi-amping?

The goal is a simple tower speaker that can be driven by a single amp. I will experiment with super tweeters sat on top of the cabs as well, because the Tannoy dome rolls off gently above 10 - 12k and has nothing at all above 16k.

Thanks for any input!
I appreciate it.
PS I preliminarily chose the Dayton PA 380 because it is cheap enough, can get down to 40 hz in about 3 cf and is efficient enough. I'm open to suggestions that won't break the bank.

IMG_20191025_164249740~2.jpg
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Old 29th October 2019, 04:53 PM   #2
KrautNotRice is offline KrautNotRice  United States
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Forgot to mention that I want the 15" helper woofer to be down firing, as to be invisible. The only thing showing on the front of the large tower should be the 12" Tannoy, and the super tweeter on top.
The 15" woofer being down firing, does that help any at all with the crossover, or phase issues around the cross over point?
In theory it should at least help with voices and too much mids coming out of the woofer.
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Old 29th October 2019, 06:06 PM   #3
neskor is offline neskor  Serbia
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That Tannoy driver is probably 3142

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Old 29th October 2019, 06:08 PM   #4
KrautNotRice is offline KrautNotRice  United States
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Quote:
Originally Posted by neskor View Post
That Tannoy driver is probably 3142
It certainly looks EXACTLY like that one, thank you for posting this info!!
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Old 29th October 2019, 06:48 PM   #5
planet10 is offline planet10  Canada
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Need Help: Designing 12" Tannoy + 15" Woof
Quote:
Originally Posted by KrautNotRice View Post
...a pair of Tannoy CMS 1201 DCT 12" dual concentrics...The driver model # is 1276
I believe this is the same driver i am looking to score (in a set of T12). I have found that trying to get decent bass out of a Tannoy even the big ones requires an ugly alignment if you are doing a reflex box, so adding a woofer is a really good idea. As well as real bass, it should improve the midrange (and the top if the moving cone is disturbing the tweeter).

ir you want to do a passive XO you really need a woofer that is 3-6 dB more sensitive than the midbass.

But crossing as low as you should (id suggest 150-200 Hz as a start) you will quickly find that going active (ie 2 amps) could be cheaper, and certainly WAY easier to get right than trying to design a passive.

dave
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Old 29th October 2019, 06:58 PM   #6
neskor is offline neskor  Serbia
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Definitely you will need active 15".
I will also cross somewhere between 150-200 Hz.
Maybe something like this will be good for bass. It has DSP
Dayton Audio SPA500DSP 500W Subwoofer Plate Amplifier with DSP
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Old 29th October 2019, 07:25 PM   #7
Brinkman is offline Brinkman  United States
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Need Help: Designing 12" Tannoy + 15" Woof
That Dayton Audio product taps out its LP at 120Hz. I know because Im trying to do DIY an active midbass module and read the manual on this specific device.
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Old 29th October 2019, 07:55 PM   #8
KrautNotRice is offline KrautNotRice  United States
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Quote:
Originally Posted by planet10 View Post
I believe this is the same driver i am looking to score (in a set of T12). I have found that trying to get decent bass out of a Tannoy — even the big ones — requires an ugly alignment if you are doing a reflex box, so adding a woofer is a really good idea. As well as real bass, it should improve the midrange (and the top if the moving cone is disturbing the tweeter).

ir you want to do a passive XO you really need a woofer that is 3-6 dB more sensitive than the midbass.

But crossing as low as you should (i’d suggest 150-200 Hz as a start) you will quickly find that going active (ie 2 amps) could be cheaper, and certainly WAY easier to get right than trying to design a passive.

dave

That's too bad, I don't think I am willing to spend that kind of money on this project. I was trying for an affordable, passive tower with 15" woofer. Ultimately, I regret selling my Ashly electronic xo and several power amps recently. All of which would've helped with this project.
So in an effort to keep this a simple, passive tower speaker that can be driven with a single amp, what are my options?
Two 15" Daytons in each cab would add 3 db efficiency over only one per, and only add $300 ish. Is that an idea?
What about the passive crossover is the difficulty? Price, or performance / phase issues?
Thanks for explaining.
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Old 29th October 2019, 08:21 PM   #9
planet10 is offline planet10  Canada
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Need Help: Designing 12" Tannoy + 15" Woof
Quote:
I don't think I am willing to spend that kind of money on this project. I was trying for an affordable, passive tower with 15" woofer.
What we are saying is that going active could be cheaper (& faster) than trying to do a passive. Look at the size of parts you need if you want to try to cross that low. Decent parts are scary. 5-10mH chokes (or larger), 100-400 uF caps.

You could start with a PLLXO for XO duty ($<<20 if you don’t do a fancy case), and a decent Class D amp for the woofer can be built amazingly cheap. 1 have 2 4x100w 4Ω amps, one cost less than $100 to build, the other has a buffered PLLXO built in, it cost $200.

It also solves the big issue with finding a woofer sensitive enuff to do a passive without heavily padding the Tannoy (not something you like to do with a driver being used that low).

dave
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Old 29th October 2019, 08:42 PM   #10
KrautNotRice is offline KrautNotRice  United States
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Quote:
Originally Posted by planet10 View Post
What we are saying is that going active could be cheaper (& faster) than trying to do a passive. Look at the size of parts you need if you want to try to cross that low. Decent parts are scary. 5-10mH chokes (or larger), 100-400 uF caps.

You could start with a PLLXO for XO duty ($<<20 if you don’t do a fancy case), and a decent Class D amp for the woofer can be built amazingly cheap. 1 have 2 4x100w 4Ω amps, one cost less than $100 to build, the other has a buffered PLLXO built in, it cost $200.

It also solves the big issue with finding a woofer sensitive enuff to do a passive without heavily padding the Tannoy (not something you like to do with a driver being used that low).

dave
Snap, that really puts it into perspective, thank you.
I love going active and biamping, don't have to convince me that it's superior, it's just that unfortunately I let go of all that equipment.
If it's not feasible to execute as planned, a tower able to be powered by the average integrated, even tube amp on occasion, then I will change plans and build small monitors with these drivers instead that will serve fine in a small size room. Such a monitor, as long as it reaches down to 60 hz, plus room gain in a really small room should still be a fun speaker to keep in the rotation.
Just for giggles though, roughly what components would I need to build a passive for the low pass section of a 15" 8 ohm Dayton around 150 hz? Just a single inductor and cap enough? Electrolytic caps are cheap, even large ones, so the real expense is a huge choke?
Dayton Audio PA380-8 15" Pro Woofer
So I can at least ball park the expensive of building that passive low-pass.
Can I get away with NOT high passing the Tannoy if I keep it in a separate small sealed enclosure within that tower? And the 15 is down firing.
THANKS!

Something like that?
Dayton Audio 10mH 18 AWG Perfect Layer Inductor Crossover Coil

400uF 100V Electrolytic Non-Polarized Crossover Capacitor

Totalling about $30 per cab. Or am I way off?

Last edited by KrautNotRice; 29th October 2019 at 08:46 PM.
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