Need help building open baffle/bass reflex hybrid

From what I understand about the TC9FD18-08, it's not a good candidate for a BR. It has a pretty high Qt. .89, which makes it a better sealed box, open baffle, or maybe even TQWT candidate. I've seen a rule of thumb that a Qt above .50 is better sealed and less than.50 is better for a BR configuration. Like any rule though, I'm sure there are exceptions.
Mike
 
Bringing this back form the dead ..
I bought the parts to build a pair of these a few years ago. Finally got around to slapping them together. This was literally a weekend project using scrap 3/4" MDF. Got everything cut and glued up one evening ... all the routing and painting the next.

I am running the drivers in parallel with no filter cap. Currently the Brios are full range through a MiniDSP 2x4 .. sitting on top of a pair of HiVi D8.8 woofers in sealed boxes. The rolloff for the woofer is 100Hz at 24dB. A few other tweaks in the MiniDSP .. I have a low shelf boost on the Brios at 180Hz (3dB) and a high shelf boost at 4KHz (2dB). I also have a -3dB notch at 1600Hz just to take out a little boxiness. The low shelf helps integrate with the woofers, the high shelf adds a little sparkle.

Normally a pair of large Heil AMT tweeters sit on top of these woofers .. crossed at 1KHz. I can't say the Brios compare to those as far as detail and openness .. but these little guys are impressive.

They are in my office (10'x20') and I can get more than acceptable volume without breakup. Big image .. you would never guess its 3" drivers. Tons of potential here.

Playing some live tracks through them really makes them shine .. Little Feat's "Waiting For Columbus" sounded huge .. lots of detail. All the Steely Dan I threw at them worked too :)

For $50 in parts .. you can't go wrong. Just pair them with some good woofers and get ready to rock.

An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
 
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Would the single cap be to flatten out the dipole peak (so it crosses above the peak in frequency) instead of having the objective to prevent the driver from bottoming out?

A view all around and a talk with the designer: https://www.youtube.com/watch?v=XdHzfGfVjbw

Tried to click on the link but it says its private? Is there any other option to view. I also was curious on the use of 20uf capacitor - whether it was to protect the driver or provide some kind of cross over
 
I'm not technical I have to say beforehand.
I wonder if you need to use 2 exact the same drivers for this to work this well. Aren't the plusses of this speaker (airiness, like being there, not easy to point out etc...) not just the plusses of a good implementation of an Open Baffle?

Wouldn't this be working as good when combining a (mid-)woofer with one TC9 (OB) to support in de lows?
 
Yes, it's called a FAST, or WAW, and it's been done extensively.
The Nola Brio is a different speaker. It needs the drivers to be the same.
Too bad the drivers need to be the same. I hoped the specific sound drscribed was mainly because of the use of an OB.

I'll try a W5-1138 with an OB TC9 in my desktop. Or perhaps maybe even a Nola with a W5-1138 (2.5 way/ FAST) as (large) desktop speaker.
 
I'm thinking about upgrading this idea, and include a woofer directly in the build.

Using a different shape, and not bother with a crossover for the bottom woofer, instead using a sub amp to drive them separately.

I like the renderings I made.

I think I will slowly build them.

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@perceval Did you happen to make those with the visaton B80? At one point there was mentioned to move the OB driver in the middle. Would it work as well? It looks a lot like an old JBL speaker. I like it a lot.
 

sharpi31

Sorry if this has already been suggested - I’m reading through the thread slowly. Is it possible that the two drivers are in series and the single cap is used to bypass one driver? That would have only one driver delivering HF (OB?) and both delivering LF.

I'm leaning towards sharpi suggestion here... The reasons are:

  • The Brios state 8ohm nominal impedance.
  • " " " 90dB sensitivity.
  • At an 1.5 speaker usually one driver is LP.
  • Dual Hi freq from two non coaxial drivers brings comb filtering problems at hi freq at close listening, because drivers emit wavelengths comparable to drivers distance.

TC9 not being offered at 4 ohm ohm tho points in other way, but maybe those are not really TC9's or are OEMs TC9 at 4 ohm (which may give about 90dB (more like 87-88dB at the following crossover scheme). Also, both TC9's have a really high Qts for ported, so again those may be OEM, or a different, alike driver.
This is for the TG9 4 ohm, which may be some alternative for someone who ended with 4 ohm's speakers, (Its tru tho that the cap may be small to get a LP at -3dB at about 1K, which would be desirable based on drivers distance)

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As the top driver is not only LP but attenuated 6dB (as the other in this freq range) the summed response will give the actual response of a single driver, but with (some) BSC and Dipole bass. Also the rear wave is attenuated, which would be more beneficial in non treated rooms, as rear reflections will come at half level (which may be closer to what the brain expects from rear reflections at say, a concert hall). This attenuation at the same time may bring Xmax of the OB driver to a more comfortable figure, and require less excursion from the ported one, as it's attenuated by the same ammount.

I'll try this, as i have 4 TG9's 4 ohm. If it doesn't work as intended, then i will have to get some inductors and make something like what kindly was discused in this other thread (making a blackworm here): https://www.diyaudio.com/community/threads/who-has-chp-90.396843/page-2#post-7494953

Edit: The responses from the drivers correspond to the TG9s at an IB, that may explain the reason why the other is ported, as the sum wont be perfect at the lower end...
 
The cap on the OB driver was to make sure it doesn't go flapping aimlessly, trying to reproduce low end stuff.

As the TC9 doesn't really have a rising response, and by toeing them out a bit, one could achieve a similar effect as a BSC. Maybe combined with a bit of combing from the two drivers.

I get that conventionally, a 1.5 XO seems logical, but the TC9 drivers are so small, what kind of bass output are we really looking at here?

Pretty sure they were crossed the highest possible to a pair of powered subs, they usually have a dial up to 200Hz.
 
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