TB 2" FR project...loading ideas?

[mondogenerator]

Ive just bought some of these lil 2" TBs:

http://www.tb-speaker.com/detail/1230_04/w2-800sl.htm

Im thinking of a small computer speaker set up running fullrange, OR some kind of FAST system. These drivers may not be optimal in either configuration, high fs etc but the overall flatness of the published FR, low mms, and the cheap price swayed me into a cheap(ish) FR project.

fs = 160hz
qts = 0.25
vas = 0.22litres

judgin by these ts im planning either sealed box or aperiodically stuffed TL, to assist in rolling of LF , to integrate with a subwoofer.

anyone have any other ideas, or possible advice?

 

[mondogenerator]

the low qts and high fs mean that in winisd i need a 30cc 'box' to get Qb of .72, AND A -3dB point of 450hz.

not sure thats much good for a FAST design? maybe im wrong....

increasing box size to .2 litres gives me a Qb = .35, and a nice roughly 6dB/octave roll off, with the -3DB at 500hz instead.

any suggestions or have i bought myself some nice wide band tweeters for something?

 

[badman]

Nice wideband tweeters, yep. You can do a 500Hz Xo, but you'll need to assist the acoustic slope electrically. I'd probably go with a stuffed, open backed box, and a low order 1kHz XO with a very good midbass.

 

[norman bates]

I've wanted to do a short line array of 4 x 2" drivers (vertical array).
The 800sl had good comments from Japanese users, but the low qts seems to be a deal breaker. Maybe a resisitor in series can help.

I don't believe the graph on the partsexpress site, but I do believe this one. Notice how it falls off on an infinite baffle.
http://www.solen.ca/pdf/tangband/w2800sl.pdf

Here is a quote
"TangBand W2-800SL
This unit is a unit other than 5cm, aging (RUNNING) will take longer to come up with a very smooth sound to get used to once. Is it because of the magnesium diaphragm is a great sound that is both sharp and smooth. Depict a very good habit of the amplifier. 5cm As is true of the other units, 5cm baffle with minimal skills and spatial representation of the diaphragm will not win any other speakers? HDB-800R In particular, HDB-800R make a noise, so useless, as you also would not look at the graph below, in horribly flat, and sharp. "
Google Translate

They must measure the driver a couple of cm from the cone to get the response that flat.

I think the 803sm would work better as a 2" nearfield and the qts = .4, although wolf commented that the Fs was more around 220hz instead of Tang Band's listed 160hz. Zero bass.

Then again, the new gen2 alpair 6 paper cone should be better.

Norman

 

[woody]

I know a qts of .35 looks like a 6db/oct roal off but it's realy 12db/oct . Just look at
what happens way below resonance.

 

[mondogenerator]

I know a qts of .35 looks like a 6db/oct roal off but it's realy 12db/oct . Just look at
what happens way below resonance.

i meant QTbox = 0.35 ie very low. the roll off IS 5-7 db/octave with this overdamped tuning, the thing that would stop me using this alignment would be the overdamping, and the possible over excursion at lower frequencies, when compared to a optimally damped alignment.

To the wise one, who posted about the series R to increase Qts; many thanks, THAT particular idea had escaped me completely. Im pretty sure a small resistance would help me tune the driver better.

 

[mondogenerator]

the drivers arrived today!



the lil 2" TBs arrived in the post today, courtesy of parcel-force, and in perfect nick. I had to call short a Christmas shopping expedition i had to connect these things up and have a mess about with them.

out of the packet and connected straight to my amp they sounded a little hard in the uppermost octave, as i expected to some degree, from the published FR plot/s.

next i mounted one on a baffle about 2ft square, and the sound was far more balanced, than just the chassis alone. however i have to say i have some doubts about running them fullrange as the xmax is only 1mm, so in order to allow a slighly louder testing session i placed both together vertically on the same baffle, running the other speaker channel thru the ~0.6Qb sealed box with visaton al130 in it as a test box. this was rolled off with somewhere between 3 and 5 mh, although ive added 50uf cap and playing with resistors, so the mini experiment is in a state of flux at the mo!

i am however pleased with the sound of the drivers, most particularly the pair in series, and maybe an array of 3 or more maybe considerable. i know little about line arrays tbh, but with the 2 drivers alone i didnt experience any severe combing. mind you im not sure if less than 3 drivers exhibit that behavior.

 

[chris661]

I was going to say that, if you're looking for a FAST system, I have 4x Visaton W130S for sale.

Still, you've got the Al130 drivers, so there's not much point.

Good to hear you've got them up and running.

 

[norman bates]

you can probably get away with 4 of the 800sl in a vertical array assuming you are the only one listening to them.

Remember 4 of the 2" drivers have slightly less area than a 4" driver, so running a fast system crossed at 200hz may be feasabile. I found 200hz 24db with 114cm2 area acceptable for occasional cranking yet keep the midrange magic of full range drivers. And the falling response may be a problem regardless of sealed /ported /any box.

Here is the nonsuch4 using 4 x bandor 50mm units (run wide open, no baffle step) with a woofer (or sub, I can't remember). The centers are 2.5" apart. Each bandor cone area was around 26cm2 each (larger than a 2"). Total area is around the area of a single Alpair 10.
[IMGDEAD]https://i959.photobucket.com/albums/ae76/fullrangebates/nonsuch4.jpg[/IMGDEAD]

I play with a dual 4" tang band and combing is a pain for everyone else but not at my chair.

I look forward to your comments.

Norman

 

[borispm]

This reminds me of the Audience bipole arrays. Should be fun to have 8 drivers or more in bipole array. Maybe with some simple passive equalization to boost the midbass, so that it's f3 can be made into 100-120Hz range?

 

[norman bates]

I don't see the harm in eq while also placed on a wide wide baffle. It's all about trading number of drivers, how much eq, and the volume/music you listen to/at. I try to not use any eq.

The audience a3 driver has a rising response that counteracts some combing (larger frame for a 3.5" driver).

I think 10"-12" is about the max tolerable driver frame combined height for me sitting 14' away. You can run more drivers then boost the high end. Your happiness is up to your own ears. Experiment and find what works for you. Try some tall full range arrays. I don't like arrays, not my cup of tea, but it could be yours.

Norman

 

[mondogenerator]

thanks for the comments. i must confess im not much of a fan or line arrays either, and im not sure i will go this way. however the pair of drivers on a single baffle did exhibit a smoother top octave than a single driver alone, maybe this is an artifact of an array-i have no idea

since this experiment, i have added my old audax ap100zo to the baffle, with a single TB driver. the response certainly isnt flat, but the integration between drivers 'feels' nice. I have been planning to use these woofers in a similar way to this page i found AGES ago..with a series R of 3.3R, ive calc'd the Qts can be bumped up to around 0.5, making it far easier to load (i think lol), since this gives a voltage ratio of 1:1 roughly, so i get 6dB drop.......figured it was 3 dB POWER drop, which would integrate perfectly with what drivers i have. assuming ive got the math right!

Audax Mini-Monitors - Experiments

so im back to square one....

ive built this (in a temporary form) as well as the audax HT system that was published when these drivers were still easily available. i basically modded the centre channel, removing the ap200zo and the HP on the ap130zo. anyway, im now considering modding one of these designs to use the TB as wideband tweeter, as the audax tw025f1 was never perfect, and in all honesty these little 2"ers present far less issue with a experimental (read botched by ear) system.

given their low power handling, im leaning towards modding the hennessy design and ditching the audax tweeters.....although the bigger Audax HT system would maybe benefit more.....ive even considered waveguide loading the fullranger in an attempt to bolster the low end a little, and cut excursion a little, but again im no expert and im sure a 2" throat would trade low mid extension for HF attenuation....

once again, im stuck with a decision.....mind you its nice having so many rainy day projects!

 

[norman bates]

some use 2" drivers as a mid tweet, crossing around 500hz.

If I remember, the 2" jordan could be used the same way. You could push it lower as you added more drivers. Then again, many did not see any benefit to using more than 4 of the 2" jordan drivers.


Some other options include a $20 2.5" peerless 830984 than has 22cm2 69mm frame (less than 3") or maybe the tang band neo aluminum w3-1401 has 3.2" frame has 32cm2 for a short array.

The small drivers are just so small, 2" driver have 13cm2 of area. 4 of them barely equal the area of a single 4" tang band bamboo, and I need 2 of the 4" bamboo minimum per speaker.

Norman

 

[mondogenerator]

run in.....and im happy as a pig in $|-|1T©

After running them in for about 100hours with low level sine sweep 20-100Hz T= 30s, the slight inital sizzle and clappiness has all but gone, and comparing them with tweeters I know are good from 3-15k within+/-2dB, they sound comparable in tone, although with that metal cone 'detail(or whatever it is?)' that soft domes dont have. 2nd thoughts; its maybe the polar response of these things. i guess theyre omni over really quite a massive range, and that initially worried me. after thinking though i dont think of it as TOO much a problem if i get them crossed low enough to match the directivity of the woofer. so bigger woofer, and i have to go lower in the HP xover. so realistically i COULD just use as normal tweeter with the 4" audax, and achieve a small sealed monitor with a respectable polar over entire FR.

pairing them with my old audax AP130ZO in 15l BR, ive mounted on in triwall card baffle about 2x3', and offset about 1/3 up and 1/3 across, probably NOT the best position but i have to say it was a little like a lion kill in a wildlife documentary, a bit of a hack and mount affair.

then i proceeded to cut a 6" hole so the audax woofer would fire thru the baffle, box on its side, and the 'flap' left from cutting the hole was left attached at the top to baffle off the TB's backwave a little, since there was a hole thru the baffle next to the driver now.

i found that adding 2.2mH to the existing xover rolled off the audax well, probably about 1kHz...its been a blur of experiments

i figure i got total 2.5-3mH maybe, with a 5uF cap in parallel, ill have to work it out when i have more time!

then i used the w2-800sl with 0.22mH LP to help roll off the HF rise a bit. this worked fine till i got a little louder, when the 2"er complained a little...THD LOTS. but its robust enough for near field, the THD would force you to turn it down if you got it loud enough at desk distance.

however adding about 30uF helped matters cutting excursion enough, and with 10R on the driver side, i think im changing Qes AND padding to match to the audax;

is that actually possible?

if it is itd be one of the things where there can be no bad side!

If i get round to sitting down and doing some sums, then i might actually try to work out the xover that way lol.

all in all, im pretty chuffed with these little things as i had an awful feeling just post purchase, that theyd be cheap and nasty.

Thanks for some idea guys, im thinking front to rear TQWT (driver at front, vent at rear; line running in the depth dimension. Using Audax AP100ZO in a sealed box, about 4½ litres, with the tangband in a compartment of the box. that way, ill have one non parallel wall, where the partition is. box media is likely to be granite floor tiles, glued with epoxy(presuming i can), heavily lined with felt/carpet/underlay and filled with BAF and cubed acoustic foam.

anyone with any further sage advice is most welcome to contribute

cheers!

 

[mondogenerator]

so an amibivolent(?) ending...

it appears i have a solution to what to do with the audaxs i got lying around, but the sad part is i still havent found an FR driver i want to buy enough


actually now im unsure if i should start this post else where, or just ask PLANET10 to move it......