Tang Band W5-704 and a TB ceramic tweeter

[sreten]

Hi,

19L tuned to 36Hz gives a nice tapered bass response (Zaphs parameters)
down to the mid 30's, but you can't expect a lot from 3mm excursion,
and 5", unless you have a small room.

No criticism intended, but a good 6.5" is always going to outperform
a good 5" in a ~ 20L box, regarding undistorted low bass SPL, but
a 5" can go a little lower extension wise, but less efficiency and SPL.

rgds, sreten.

 

[imagios]

Looking forward to seeing where your design heads too Imagios, please keep us updated.

Well so far I´m solving a tool issue, since cutting out circles in the wood is not a easy doing, if you want to have it done decent...but that is a issue I discuss here: http://www.diyaudio.com/forums/equipment-tools/220290-dremel-trio-sufficient-tool.html
in the mean while, I´m thinking whether not to get the MatCAD plugin from Martin J. King, and look for a transition line result for the driver,... just out of curiosity.
But any way I will keep you updated

 

[Allstar]

Hi,

19L tuned to 36Hz gives a nice tapered bass response

That's actually quite encouraging. I do have a small room ( with some trapping ) and the design is intended to be used at consistently moderate levels. I have a set monitoring level of about 83dB SPL and listen on axis at about 1 meter.

The size and shape of the cabinets is quite intentional so when I inevitably have a go at version II, I agree 6.5" woofers would likely be a better fit. Nonetheless I'm looking forward to seeing what can be achieved with the W5 704D ( I'm pairing it with a Vifa DX25TG09-04 incidentally ) and will certainly be trying the tuning you've recommended.

 

[Allstar]

But any way I will keep you updated

Thanks.

Yes, I toyed with the idea of using a transmission line and Martin's worksheets, but being new to designing speakers from scratch I felt the learning curve might be a bit steep for me. At least for now.

 

[imagios]

Thanks.

Yes, I toyed with the idea of using a transmission line and Martin's worksheets, but being new to designing speakers from scratch I felt the learning curve might be a bit steep for me. At least for now.

Yea for me its the same therefore I start with the vented box
(Still the transition line is something that I would at least like to see simulated)

 

[imagios]

OK I have go the MDF today, since they had no 15mm I have gone for the 18mm MDF, nice pieces good quality, but I made a stupid mistake and se the parameter wrong, now the internal volume is 14,5l and the pieces need to be adjusted to really fit together...
I ended up in a situation when from each corner of the desk I have to take 9mm so that the plates lock together... and I will have to do that with the small Makita I ordered...
Well a lot of work is ahead, I will than measure the real inner volume and redo the simulations, really a nice start.

 

[imagios]

OK the measuring tool arrived today I could measure the parameters.
here they are:
first one
D 125.0 [mm]
Re 6.18 [Ohms]
Fs 47.78 [Hz]
Zm 39.38 [Ohms]
BL 4.89 [N/A]
Qms 2.801
Qes 0.521
Qts 0.439
Vas 34.960 [liters]
L10k 0.32 [mH]
n0 0.70 [%]
dBSPL 90.54 [1W/1m]
Ms 6.71 [grams]
Cms 1.65 [mm/N]

Second one:
D 125.0 [mm]
Re 6.14 [Ohms]
Fs 49.12 [Hz]
Zm 41.47 [Ohms]
BL 4.90 [N/A]
Qms 2.777
Qes 0.483
Qts 0.411
Vas 36.220 [liters]
L10k 0.31 [mH]
n0 0.85 [%]
dBSPL 91.38 [1W/1m]
Ms 6.13 [grams]
Cms 1.71 [mm/N]

now in diagrams:

now I hope I do not overspam it here but here are some more pictures:

 

[imagios]

OK now as you might see the measured parameters are a way from the datasheet parameters, I even recalibrated the instrument twice and remeasured the speaker, with the same result... now it seems to screw up my project and I have already catted MDF pieces...but with the measured parameters this is a far from what I planed

 

[Allstar]

Thanks for the update imagios, sorry to hear about the problems. Odd that your Vas measurement is about three times the value of others I have seen. If it were me i'd be suspicious of that.

 

[imagios]

At this moment I really don´t know what to do, its like I would measure a totally different driver. There must be a error in the measurement, I can not imagine TB would have such a difference between the datasheet and reality...
I´m open for suggestions, any one having similar experience?

 

[giralfino]

If I'm not reading wrong the QC date, you have some 3 years old drivers, at least the tweeters.
If the woofers are also "old" I'd "massage" them with a 20-40Hz tone at full x-max for some hours. Let them cool and re-measure.
Another suggestion: I use Arta, and I found that the system gives me more realistic TS parameters when I limit the range from 20 to 100 Hz or something like that.
Ralf

 

[imagios]

The driver are old models but I took the first time out of the box, they are new ordered from the shop in september.
Migh te that they are not "broken in" so it may put a different measurement, but definitely
the Vas is impossible, so it must be the measurement.

 

[giralfino]

I use this method: Jig for Arta
The jig is pretty easy to build, and the Arta can be used in the free version, so IMHO it is worth a try. If the results are consistent between Arta and WT then the problem is in the drivers.
Ralf

 

[vacuphile]

All TangBand speakers I ever measured are way different from the specs. Usually actual Qt and Fs are considerably higher, and Vas lower than specified. TB is not the only manufacturer where this is the case, but they are one of the worst as far as my experience goes. It's tricky.

 

[imagios]

hmm the question is as well how reliable this dayton audio test is, I used the added mas method with a tape, I cant imagine such a difference, I mean Vas=36lit. ist just not possible for a 5inch speaker, with a Xmax of 3,3mm, there must be a measurement error.
I resimulated the box with my measurement, but with the Vas of TB datasheet, and I will continue as planed, in the most worst case, I just seal the box, and start a new project for a subwoofer.

 

[flaevor]

how much weight did you add? my understanding is that if you used too much that could be the source of the error.

 

[imagios]

how much weight did you add? my understanding is that if you used too much that could be the source of the error.

9,9grams

 

[imagios]

Ok gents,
here is the new progress, the plates for the housing are ready:
http://hex.dan.sweb.cz/TBBookshelf/20121009_193556.jpg

I as well measured the tweeters:
http://hex.dan.sweb.cz/TBBookshelf/tweeter.bmp

the exact inner volume now is:12,769 l
that gives a vent of 3,5cm x 10 cm, air velocity still OK for 10W input. turning freq. 43Hz

now comes the tricky part, and I will need help with that I need help as most probably most newbies... the cross over.
I mean I know inductors take the low Freq. cap. the high but thats it...
First of all how many level will I need? just one for the cross over freq. between the tweeter and midbass, or shut I use first a highpass to cut off very low freq.?
What freq. would you recoment to get the thweeter working he has a free air res. below 750hz, but the midwoofer goes nice till 5kHz. It seems like a lot of room to select.
Should I as well lowpass the thweeter above lets say 30kHz?
Or would be just one simple cross over betwen midbass and tweeter be the best approach?
Can someone please advice, as I will not be able to do that on my own.
Many thanks upfront
Daniel

 

[imagios]

OK since no one gave any answer, here is what I have so far,
I would select the cross over freq. at 2500Hz after reading some review on the tweeter
that means a first order BW low pass for the midbass = inductor 0.684 mH (2.512Hz at 10.79 Ohm;6db/octv)
Now the high pass of the tweeter the second order BW=8.376 uF + 0.479 mH (2512Hz 5.347Ohm; 12db/octv.)
would this be correct???

 

[wolf_teeth]

Textbook equations will not get you a good sounding speaker.

Later,
Wolf