The WIBAQ: TABAQ Design with Betsy K

[xrk971]

I think Visaton BG20 may be a good alternative. The vent dimensions can be calculated using the AMLTL method. With a Qts of 0.44, Vas of 110 liters, and 92dB sensitivity it seems to be a good choice. Pricing on this driver is also quite bargain priced in the US.

For a MLTL as designed for Betsy K per dimensions given in post #1 (11in wide x 45in high x 16.25in deep with 1.625in tall x 4.0in long vent), you can drop in the Visaton BG20 into the same box with one mod - change the vent from 4.0 in to 6.0in long. Should work almost the same in terms of sensitivity and bass extension.

Here is Betsy K:

Here is BG20 with vent extended to 6in long:

The sims are for the speaker placed against a back wall so you have some cancellations and reflections, but also bass gain for 1/4-pi placement.

In either case, I would recommend some EQ or BSC to balance the highs with the bass. About 1.0 mH and 3 ohms should do the trick.

One note, if you plan to use the speaker far away from a back wall so you don't have bass enhancement, keep the vent at 4.0in long and this should increase the bass output. Here is response with 4.0in long vent, placed far from back wall (2pi) with 1.0mH and 3ohm BSC:

 

[cyrza]

Thank you xrk971 for a instructive reply! So Visaton BG20 would nice budget driver to try.

 

[xrk971]

Yes, it does look like it should work well.

 

[j.michael droke]

2pI simulation w/BSC

For a MLTL as designed for Betsy K per dimensions given in post #1 (11in wide x 45in high x 16.25in deep with 1.625in tall x 4.0in long vent), you can drop in the Visaton BG20 into the same box with one mod - change the vent from 4.0 in to 6.0in long. Should work almost the same in terms of sensitivity and bass extension.

Here is Betsy K:

Here is BG20 with vent extended to 6in long:

The sims are for the speaker placed against a back wall so you have some cancellations and reflections, but also bass gain for 1/4-pi placement.

In either case, I would recommend some EQ or BSC to balance the highs with the bass. About 1.0 mH and 3 ohms should do the trick.

One note, if you plan to use the speaker far away from a back wall so you don't have bass enhancement, keep the vent at 4.0in long and this should increase the bass output. Here is response with 4.0in long vent, placed far from back wall (2pi) with 1.0mH and 3ohm BSC:

Hi there X: 2pI simulation, w/BSC is really flat, dramatic change, any analysis on the three mid range peaks and two later dips? They are at the same places as the first graph, although the peaks are attenuated some.
So are these design anomalies? Or related to geometry. Are they expected to be present in a built enclosure, if so can they be corrected by stuffing changes? ...regards, Michael

 

[xrk971]

Those are all back wall and floor reflections - the difference was just setting the "Reflection" switch off. Actually, it might be 4pi come to think of it. Baffle step is still there - just no reflections from nearby walls. Stuffing will control the sharp spikes on the green curve which really won't make it out of the vent.

 

[Thrashcomics]

I am very intrigued by your instrucables article. My only concern is volume and punchiness. I am running a mcintosh ma6100. It puts out 70 watts per channel. I listen to thi.gs ranging from run the jewels to marina and the diamonds to canibal corpse to periphery to nofx. In digital and vinyl. I like music loud. Will this speaker do what I want it to do or should I look elsewhere?

 

[xrk971]

I am very intrigued by your instrucables article. My only concern is volume and punchiness. I am running a mcintosh ma6100. It puts out 70 watts per channel. I listen to thi.gs ranging from run the jewels to marina and the diamonds to canibal corpse to periphery to nofx. In digital and vinyl. I like music loud. Will this speaker do what I want it to do or should I look elsewhere?

The BetsyK driver is quite sensitive and as you can see from the sims it hits 95dB at 2.83v or circa 1watt. It will probably hit xmax around 16 to 20watts. Maybe 105dB max SPL. That should be plenty loud for most people. But when playing that loud a full range driver will sound congested and distorted. If you really like it loud and clean I would suggest a 2-way like a FAST (woofer cross over at low frequency like 300Hz). That lets you apply power and limits excursion on full range for less distortion. The bass will sound more full too.

If you want full range point source magic, look at the Manzanita open baffle in Multiway forum. That can handle probably 60watts and get pretty loud and clean. Or go with any number of great multiway speakers in that forum. Troels Graveson, Xaphaudio, Jeff Bagby, have many great designs. You might like the super efficient waveguide series designed by Bagby that are flat response in the high 90dB's using horns and CD's with a pro audio woofer. Take the Fusion 12 Tempest - They are available here:
http://www.diysoundgroup.com/waveguide-speaker-kits/fusion12-kit.html

 

[Strozzi]

Hello,

Last autumn, i finally made the WIBAQ's, and have used them for different periods of time, but found them a bit forward for use as permanent main speakers.
I made the Optional: BSC Circuit as recommended on this site : DIY Hi-Fi: WiBAQ Speakers - 5 , and have played them for many many hours, so they should be more than broken in, but i still feel the midrange is a bit harsh/edgy,
I was wondering if the values of the components in the filter could be adjusted for more'tuning' of the sound?
Thanks for any insight/tips about this.

Regards, Oyvind, Norway

 

[Bjohannesen]

I have not SIM BSC for this design. However I would use 3.9 or 6.7 Ohm as a starting point for testing with the 1.0 mH coil.

Regards
Bjørn

 

[xrk971]

Be prepared to add more resistance in 1 ohm or 2 ohm increments until it sounds balanced, Keep in mind that overall sensitivity drops as you add more but sometimes it takes 6.8ohm to 10ohm depending on how "hot" the driver is to start.

 

[larryldspkr]

Strozzi, try a 3k notch filter. 10uf cap .3mh coil and 6-10 ohm resistor, all in parallel and in series with the driver.
This worked well for me, and I didn't use BSC filter just the notch.

Larry

 

[Strozzi]

Thank you all for your answers, i really appreciate it!
I will try your suggestions and hopefully get the WIBAQ's more balanced, as they have a lot of qualities. It would also be very satifsfactory to actually use the speakers one has built, as the main speakers.
And if i didnt have such a large listening room, i would definately purchased a pair of your SoundSommeliers, Bjørn / Bjohannesen! They look fantastic, and i bet they sound fantastic but i just dont dare to order them, as i am afraid they are too small for my room of 4 x 6 meters = 24m2

 

[Bjohannesen]

Hi Strozzi
The Soundsommeliers would not play loud enough for a party in your room but would be fine for listening at moderate level.
Hi
Bjørn

 

[LZ0]

WIBAQ simulation with TB W8-2145

Hi Bjørn,

I am very interested if the Tang Band W8-2145 driver is suitable for a WIBAQ build. Would it be possible to perform a simulation with it?

Looking forward for your feedback 🙂 Thanks and best regards!

 

[peroz]

For a MLTL as designed for Betsy K per dimensions given in post #1 (11in wide x 45in high x 16.25in deep with 1.625in tall x 4.0in long vent), you can drop in the Visaton BG20 into the same box with one mod - change the vent from 4.0 in to 6.0in long. Should work almost the same in terms of sensitivity and bass extension.

Here is Betsy K:

Here is BG20 with vent extended to 6in long:

The sims are for the speaker placed against a back wall so you have some cancellations and reflections, but also bass gain for 1/4-pi placement.

In either case, I would recommend some EQ or BSC to balance the highs with the bass. About 1.0 mH and 3 ohms should do the trick.

One note, if you plan to use the speaker far away from a back wall so you don't have bass enhancement, keep the vent at 4.0in long and this should increase the bass output. Here is response with 4.0in long vent, placed far from back wall (2pi) with 1.0mH and 3ohm BSC:

I am also very intrigued to try the big cheapo BG20. I made a simulation of it in a wibaq enclosure with 6in port, and mine doesn't want to go as low as yours. Do you know why? Different sim system, of course, but this much difference?? I smoothet it a bit with stuffing, but that doesn't really affect the bass extension...
You said to use BSC to tame the highs, but since I am a "no filter" guy, do you think removing the whizzer cone would achieve something similar?

Any ideas how to get good performance from this driver in a smaller box?
And another question: I can't quite imagine how loud a speaker like this is. Will it be enough for outdoor picnic/party events? I know this is a bit too general question, but anyway...

 

[xrk971]

Maybe you did not turn on boundary of nearby walls and floor. Both enhance bass. Akabak is usually pretty accurate about the bass extension.

BSC is not evil it's not a crossover but a way to shape the output by attenuating highs so that the bass can be heard. Get a cheap $1 1mH ferrite core inductor and a 5ohm or 7ohm resistor and try it out. You might be surprised.

 

[peroz]

Okay, will do!
How do you calculate the BSC values, may I ask?

 

[peroz]

I'm playing with Fusion 360 and today I modeled a tabaq type mltl speaker, fully parametric. Should anyone be interested, I could translate parameters to English and find out how to share it. It really is a great program, and as far as I understand, it can export "straight to cnc"🙂

 

[xrk971]

I can simulate effect of BSC directly but I find 1mH to be the typical value needed given the baffle width of a typical speaker with 8R driver. 5R gives maybe 3dB attenuation of high shelf. 10R will be about 5-6dB or full BSC max cut. Of course the WIBAQ baffle is a bit wider than a typical 6in wide baffle so maybe 0.8mH can be used. It's a mild effect in the frequency where it starts the shelving function (high pass cut ).

 

[peroz]

OK, so the BSC circuit usually compensates for baffle's effect, which, if I understand things right, can also be handled with rounded corners and narrower speakers. But the BG20 is "hot" everywhere above 500Hz. Whould a 1mH, 5Ohm BSC compensate for that also?