Audiotechnology 3 way build + subwoofer?

[raelman]

Hello.

I have the Troels Gravesen Jenzen ATS kit ready to build, but I will filter in ACTIVE with Hypex Ncore and Minidsp. Will be placed in my sitting room 30 sq mt... but not closed, opened to first and lower floor, what means more meters

Tweeter: Scan Speak D3004/664000
Midwoofer: AudioTechnology 18H52-06-13-SDKA
Woofer: 10" AudioTechnology 10C77-25-10-KAP

Woofer takes about 65 liters vented with F3=32Hz

Aesthetically, I'd prefer a 4 drivers cabinet rather than 3 drivers one (the original) so I'm planning to add a 10" subwoofer.

Adding to the original design one SB Acoustics 10" SB29SWNRX-S75-6 subwoofer, UNIBOX calculations are:

Woofer: 10" AudioTechnology 10C77-25-10-KAP Sealed 15 liters (F3=72Hz) Would be cut at 80Hz

Subwoofer: 10" SB29SWNRX-S75-6 60 liters vented F3=22Hz

What do you think about?
Any help is welcome.

Thank you

 

[Lojzek]

I'd suggest to build the kit as is with a modification of adding a passive radiator instead of port. That will give you the looks you like so much.
The fact that often woofer Qts measured for yourself looks to be higher than specified will work in your favor of achieving a lower bass cut-off point.

 

[raelman]

Any suggestion regarding to the passive radiator?
And will it go deeper than the ported option?

 

[Lojzek]

I'll report back later when I do some simulation.

 

[raelman]

Thank you

 

[Lojzek]

I have tried 3 Dayton Audio, 1 SBA and 1 Seas SP26R and only Seas represents a good alternative to a ported box although with slightly higher cut-off. Since there is no official Qmp data on Seas radiator, I've decided to use a value of 3 which supresses the motion of PR at Fb better than higher Qmp's. I'm certain that it doesn't pay off to use a PR in this case in regard to performance, only if looks takes precedence. Excursion figures are related to input power of 50W. Additional weight of 18 g to PR was necessary to tune the box to the same Fb as ported.

 

[LineSource]

raelman,

Do you plan to build the Troels' ATS plus a subwoofer box, or Troels' ATS-4 with the midwoofer and subwoofer in one box?
------------
Do you plan to use Troels' passive crossover circuits for the Tweet +mid +midwoof, and only use the Minidsp for the subwoofer?
-OR-
Do you plan to use the minidsp for multiple drivers?

Troels: "What this ATS design does allow is time-alignment of all drivers due to individual - and moveable - cabs for mid and tweeter although only the tweeter may need adjustment, but moving the whole speaker the separate mid cab comes handy."
--------
"In my opinion" Troels Jenzen ATS cabinet has too many exposed edges and stepped baffles for a low diffraction effects design. Troels' stepped design is required for time alignment, which is especially important with 2nd order LR2 crossovers to equalize the circuit's 90-degree phase shift. A full minidsp crossover would include delay-blocks, and this would allow a smoother, clevely shaped low diffraction baffle. You could maintain the basic ATS shape using smooth, continuous cut bevels. A little closer to Avalon designs. T-M-mW-sW cabinet, or a separate T-M-mW top + sW bottom cabinet.
-----------
Troels ATS woofer cabinet is 352mm wide(320mm internal). The advanced motor 12" SB34NRXL34-8 woofer has a 346mm external frame and 305mm internal frame...worth consideration. The low cost 12" Dayton DS315-8 has 314mm external frame and 272mm internal frame.
===============
You might also consider removing woofer vibrations by using a side-side pair of sealed woofers with direct amp connections and minidsp for crossover plus room equalization. With dsp, smaller cabinet volumes can produce low-smooth <80H bass with a powerful amp.
You could use dual 10" SB29SWNRX-S75-6.
Dual low cost 12" Dayton DS315-8.
Dual advanced motor 12" SB34NRXL34-8 with flat SPL beyond 1kHz.

 

[raelman]

I'm planning to build troels ATS adding a subwoofer in the same cabinet.
I will use minidsp and dedicated amplifiers for all the drivers.
I was thinking on 10" SB29SWNRX-S75-6 because it seems it can go deep without a big enclosure, because Dayton needs more liters if I'm not wrong.

I really wonder if It worth the subwoofer or not needed for music listening.

 

[Lojzek]

It's not worth it. You're too concerned with numbers and that's keeping you from realizing it. Build the kit as it was designed by Troels.

 

[giralfino]

ATS + subwoofer in one box doesn't make much sense. Build the ATS as is or the ATS-4 if you want the 4-driver look. If i've seen correctly the ATS-4 uses all the ATS drivers.
Another point: without measurement equipment and/or the passive crossover transfer functions IMHO it is hard to implement an active version of any passive crossover. I'd simply build the passive crossovers, you don't need to be fancy with exotic components.

Ralf

 

[LineSource]

WinISD sims of the 10" ATC 10C77-25-10-KAP confirm that its T/S parameters work well for a ported -3db bass shelf alignment with -F3 of 30Hz when near a wall. Troels used this alignment in his 3-way ATS construction. Looks like an excellent ported woofer 3-way design for a modest size room.
------------
In a sealed alignment, the 10" ATC 10C77-25-10-KAP will perform well with a 300Hz crossover frequency to the ATC 18H52-06-13-SDKA, even when a shallow LR2 slope crossover is used, and it has natural -F3 ~75Hz in a Qtc = 0.577 alignment often praised for fast&clean transients. You can use DSP with high power amplifiers to equalize this ATC 10C77 sealed box from 75Hz down to ~30Hz equalized-flat for your room. Max SPL at 30Hz will be limited to about 96db for conservative 10C77-25-10-KAP power specs.

-So, you can get decent bass in your modest volume room from a 3-way with a sealed woofer using DSP + watts.
-If you demand high SPL deep sealed box bass, adding an equalized 12" like the SB34NRXL75-8 with 91db sensitivity would get attention.
============
DSP will set the time delays that allows you to use low diffraction flat baffles. I added pictures of Avalon and Pass Labs speaker cabinets to illustrate options to the high-diffraction multi-step Troels ATS and ATS-4 cabinets.

How good are your woodwork skills...or cabinet maker? Is there a commercial speaker cabinet which your favor?

 

[raelman]

Thanks for your answer.
I think my woodworking levels are good enough for this project: I built a very good sonus Faber cremona clones cabinets Successfully.

But I'm lack of knowledge about dsp and active filtering.

I'm planning to amp the woofer and the mid with new NC500MP OEM from hypex that gives 270w for a 8 Ohm load. I suppose is power enough for this build.

I have one minidsp 2x4 balanced for each speaker and I really know that equalisation can be done, but don't know how.

As much space I can save it would be good. The maximum dimensions are the troels one, but sealed enclosure is an option.

What steps should I follow?
I could build test cabinets and try sealed or ported.

Thank you!

 

[LineSource]

I could build test cabinets and try sealed or ported.

You could knock together an internal 2.5cuft MDF ported bass-shelf alignment test box for the 10" ATC 10C77-25-10-KAP, add some stuffing, and fire up the minidsp_HD + user manual. 3" diameter port, 8.8" long
=========
-=-=-=-=-=-=-=-=-=---=-=-=-=-=-=-=-=-=--=-=-=-==-
If you decide on a single 10" ATC 10C77-25-10-KAP ported bass-shelf alignment woofer like Troels ATS, you could consider a single cabinet Avalon clone. 2.5cuft volume for the ported woofer is the goal. The open volume behind the sealed tweeter and midrange can be used, and this reduces the total cabinet size. You minidsp with the advanced 4-way crossover should handle this. (pic: Single 10in) ATS performance in a smaller, lower diffraction cabinet. There are a few diy-construction threads for similar Avalon boxes.

=========
If you want greater flexibility to experiment with a 3-way using the 12" SB34NRXL75 instead of the ATC 10C77, or even a 4-way by adding the 12" SB34NRXL75 with the ATC 10C77 in the same cabinet, you could construct both a TM top cabinet, and a 3cuft internal volume woofer cabinet. Avalon style or Nelson Pass SR1 style are examples. Even with the advanced 4-way plug your minidsp will stuggle with bass equalization, you will probably need some passive Xover parts. (pic: Avalon xx and Pass xx)

W =360mm = 14.6" external ~ `12.6" internal
H =711mm = 28" external ~ 26" internal
D = 457mm = 18" external ~16" internal
gross internal volume ~3cuft

10C77 sealed 0.46cuft 80Hz
10C77 shelf port 2-2.5cuft 31hz near wall

12" SB34NRXL75-8 woofer with advanced motor:
sb34 5cuft port 24hz bass shelf
sb34 2cu ft port 31Hz Butterworth
sb34 2.3cuft sealed 48Hz Qtc 0.577 add 25hz Linkwithz Transform CKT
sb34 1.35cuft sealed 59hz plus massive equalization for 30Hz bass

 

[raelman]

Thanks a lot LineSource!
One question:
Why do you suggest 12" SB34NRXL75-8 instead of 10" SB29SWNRX-S75-6?
In my siimulations, the 10" SB29SWNRX-S75-6 needs a lot less volume than the 12 one.

 

[giralfino]

I think my woodworking levels are good enough for this project: I built a very good sonus Faber cremona clones cabinets Successfully.

But I'm lack of knowledge about dsp and active filtering.

I'm planning to amp the woofer and the mid with new NC500MP OEM from hypex that gives 270w for a 8 Ohm load. I suppose is power enough for this build.

I have one minidsp 2x4 balanced for each speaker and I really know that equalisation can be done, but don't know how.

As much space I can save it would be good. The maximum dimensions are the troels one, but sealed enclosure is an option.

What steps should I follow?
I could build test cabinets and try sealed or ported.

Below you find a copy&paste from another thread posted by user "john k...", you can easily understand who he is:

Step One: Learn hos to measure drivers. The only thing active will do for you is make it unnecessary to worry about the driver impedance data. But if you can not get reliable, accurate SPL data it won't matter if the crossover is active or passive.

Step Two: If you are going active, get some software that allows you to construct/design crossover filters using standard elements like shelf, notch, high pass and low pass filter blocks.

Step Three: Implement the filters using a digital crossover such as the miniDSP 2x10 HD.

Step Four: Tickle the DSP setting to fine tune the response.

Step 5: if you don't understand steps 1-4 above, seek profession help.

To recap: going active is not a substitute to measurement, if you don't or can't measure build the ATS as-is (i.e. passive).

Ralf

 

[raelman]

No problem to take measures from the drivers.
I have calibrated mic, spl meter, sound card with phantom supply and access to ARTA.
software.
If I planning active filters is because I will expend the same money in amplifiers than in passive parts.

I meant I have no experience using minidsp plugins and don't know what kind of tubing will let me do.
Some people says you can make a linkwitz transform and get deeper bass from sealed enclosures.

 

[giralfino]

If I planning active filters is because I will expend the same money in amplifiers than in passive parts.

Probably you simply compared the cost of the passive elements suggested by TG to the amps cost. The truth is that there are lots of cost improvement that can be made by choosing carefully the crossover components. By far the biggest saving is moving from a 22uF superior z-cap to a standard one, 76 to 6 Euro, and for 8 of them that means 560 Euro less. For all other film caps you can also save real money. For the coils the same apply: the 1.8mH 0.38 Ohm wax coil (48 Euro) is in series to 2x4R7 paralleled resistors, you obtain the same effect by a 1.8mH 0.57 Ohm air core coil (12 Euro) in series to 2x4R3 paralleled resistors, so another 70+ Euro of savings. For the 0.27mH wax coil (21 Euro), with the same DCR there is an air core coil at 6 Euro, for 4 of the you save another 60 Euro.

I'm not discouraging you for the active version, but the cost should not be the factor. And if you opt for the active version, you don't need to build the TG box, as already said by LineSource.

Ralf

 

[raelman]

Yes, I was considering changes in the TG crossover components for sure but, as You said, in the other hand I have the chance to change the cabinets, that is the main reason in fact to go active.

I'm planning a passive radiator to keep my aesthetic desire and have a 4 drivers look.

I'm looking for and calculating what could be the solution and will post what I think it could be.

Thanks again.

 

[raelman]

Hello again.

Here I go with my passive radiator calculations to get an Fb=32Hz

I should use a PR with 1.5 to 2 times the Xmax from my woofer, that has 7.5mm Xmax as Measured by AT, so I have to go for an Xmas of 11 to 15mm.

I can only find one PR with the weight and xmax combination:
SEAS SP26R-H9946
Xmax 12,5mm
Moving mass 42 gr
Sd 350cm2 (what means 21.12cm effective diameter)

With those numbers, my calculations are 65,7 gr, so I need to add another 24gr, although SEAS Specs says I need to add another 55gr

H9946 SP26R

Is this OK??


I'd rather prefer to use the cheaper Dayton Audio SD270-PR, but has a 10mm Xmax and the moving mass is 100gr with an Sd=340cm2 (28.8 cm diameter). Those numbers pray for 62gr moving mass, but the dayton has 100gr.

Dayton Audio SD270-PR 10" Passive Radiator

Any suggestion or Will the SEAS work?

 

[LineSource]

For your 10" ATC 10C77-25-10-KAP I have been modeling a 2.0-2.5cuft volume with a 3" diameter port tuned to 28-30Hz (8" - 9" in my model). This produces an Extended Bass Shelf alignment which typically complements room gain. Troels discusses a similar design for his ATS.

This SPL plot might be a useful comparison with your passive radiator tool, or you could start with a simple plastic pipe port and purchase the proper passive radiator after some cheap experiments.

====
I mentioned the SB 12" in earlier posts just in case you wanted monster-bass from a 3-way which your minidsp-HD could easily control. Others have commented on the challenges and costs of building an excellent 4-way.

12" SB34NRXL75-8 woofer with advanced motor:
sb34 5cuft port 24hz bass shelf
sb34 2cu ft port 31Hz Butterworth
sb34 2.3cuft sealed 48Hz Qtc 0.577 add 25hz Linkwitz Transform CKT