Need some advice for new 2 way

Hello,

Well, after debating going with a single driver system, I have decided to go 2 way. Purchased some Tang Band W6-789E's from Parts Express, and want to go with a simple vented box. My wood working skills are atrocious, so want to be able to complete the job. My question pertains to the crossover. I really want to keep it simple, and am planning on implementing the HiVi RT 1.3 planar isodynamic tweeters, and want to know if I can just cross over with a single high quality cap at about 6-7 kHz, without harm to the tweeters. My amps got about 5 watts, my room is extremely small, and I don't listen at real loud levels. Will this simple crossover scheme work? I don't wish to blow the tweets. Both woofers and tweeters are rated at 92 dB efficiency, and the woofer response goes nearly "flat" up to about 10 kHz.

Thanks for any comments.

Terry
 
Wow ! You've found the killer woofer ! 10 KHZ :rolleyes:
Now ,play that frequency through that device and tell us :mad:
I think 5 K is even too high ,3 K is were lots of woofers aim to reach ,but constrained by their size and mass ,just can't .:smirk:
Try to dial the 3k freq in some on-line crossover calculator
such Strassacker: Lautsprecher - Boxen - Selbstbau
and please do tweeter a favour and start from second order....
Hope this helps :)
 
Well ,a lot of real experts around here that can carry you throughout the voyage of cabinet and filter making . That medium-high sensitivity woofer seems quite good , Also my experience with isodynamic tweeters (infinity's emit tweeter ) was pleasant,the only enemy was distortion from the amplifier that blew one .
Don't trust on-line calculators ,where the values of inductance and capacitance are swapped between woofers and tweeter sections (they are the same)
...even if...the high pass calculator (2nd and 3rd order) has worked fine for me.
 
Hi,

I would severely recommend following the Jkim designs and using
one of the suggested tweeters, the vifa tweeter is excellent for
the price according to Zaph : http://www.zaphaudio.com/tweetermishmash/

I think a tall floorstander is your only option, say 33litres tuned to 40Hz,
its a big box for a 6.5", but that is what the parameters indicate.
A deeper bit wider version of this ? : http://www.humblehomemadehifi.com/Tempo.html
See other designs at HHH for more cabinet making ideas : http://www.humblehomemadehifi.com/Auriga.html
The latter would be fine with 18mm instead of 22mm, 22mm seems overkill to me.
But the idea makes a good finish quite a lot easier, to finish spray or use a roller.

rgds, sreten.
 
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Sreten,

I was thinking maybe even a bit larger box. Is there any problem here going with more of a golden ratio type of box? I don't much care for tall thinner enclosures. If I'm gonna listen to a box, I don't much care if it's boxy. Also, that tweeter mishmash looks very good, can't get to reading it 'til later....Vifa tweeters are fine by me....is there any problem with going series crossover, like Acoustic Reality? One of my biggest goals is to keep it simple. As always, thanks.

Terry
 
Hi,

You can go larger if you want, say up to 40L, but beyond that point
fairly pointless due to the Vas of the driver. Keeping the baffle
narrow is good for imaging and critical if using jkim's c/o designs.

Note that due to nature of the design, good sensitivity with
decent bass, power handling, especially in the bass will be
fairly low, with watts it will be the quality not quantity
that really matters.

FWIW forget about a "simple" c/o, they do not work unless
thoroughly designed properly, with a lot of drivers they are
simply not possible for sensible design.

Use the Jkim c/o design for the correct tweeter IMO.

If you want say a wide but not deep speaker you are on
your own, it is still possible to do properly with all the info
in the links, but you need to know what you are doing.

rgds, sreten.

this : http://www.parts-express.com/projectshowcase/indexn.cfm?project=MagnaCumLaude
indicates things may not be what they seem 1kHz to 2kHz for a simple c/o.
 
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Sreten,
I am carefully considering all of your input. I really do appreciate the help, just need some time to digest it. I looked over the PE thread yesterday but will go through it again tomorrow. I can get 1 ft^3 Dayton boxes pretty nicely finished from PE, so that's solved. If I am understanding correctly the jkim design preserves decent efficiency for lower powered amps?

Have a good evening
Terry
 
Which parameters to trust?

Having received the Tang Band W6-789E's a couple weeks ago, they were given a pretty good round of rock n roll for a few days before I put em back under the tree. Today I hooked them to the WT3 (Dayton woofer tester) and on both drivers measured Qts of .56
Parts Express listed Qts .39
Tang Band info says .46
I tested them several times, so I believe the WT3 is giving an honest read....

This is the type of frustration I often have encountered over the years. It makes one wonder if they are ever spot-on or just "in the ballpark". These were destined to go into ported boxes, but now not so sure. Anyone ever measure these drivers?

Best,
Terry
 
Some info...

Thw W6-789 likes larger boxes, almost 1.5ft^3 in some alignments. If you use the Dayton 8" PR, you can get some killer low end like Ed Froste did in the 'Flames' project:
FCT3.8 a.k.a. "The Flames" - Froste

I agree with the others here that the W6-789 is probably not much good above 2.5-3k tops, but it doesn't really have much of a breakup to mess with. The surround/edge is well damped, and the cone is a poly. I suggested a xover of about 800 Hz in the Flames for the W6-789.

The RT1.3 however- is a different animal. I love how its very articulate in timbre, and it is really open and spacious. BUT- don't really think about xovering much below 3k, and you should use at least a 12dB network. Being the planar variety and having a steep rolloff already, you can get an acoustic 4th order (24dB) xover fairly easily with the 12dB network.

I helped Ed with the Flames initially, and have used the RT1.3 personally. My opinion is that you might need a mid to make these drivers happy. It's a 'maybe' in terms of a 2-way. And the 'simple' part may need to be omitted....

IMG_0148.jpg


Oh- and to the AR-SXO comment further above--
I would not recommend doing that with any type of planar or ribbon. SXO's in general are somewhat harder on tweeters than the parallel variety, and being the fragility of the ribbons that they inherently are, I would think you'd toast them pretty easily. If I ever get brave enough to try a series xover on a planar/ribbon, I will post my impressions, but I will not do it unless I can waste the $80 in drivers.

Later,
Wolf
 
Thanks Wolf. I appreciate your input. I have been leaning toward a box size that is pretty much 1 cu ft to Vas (about 1.46 ft^3) in volume, that is, if I can decide which Qts is right. (Will the real Qts please stand up?) The planar tweeter idea has been put pretty much put on hold. Simplicity is still the goal, since I listen mostly in the near field, at lower volumes, so some experimentation is in order, and I realize the highs will likely start to beam at about 2.2Khz, so a lower than desired xover may happen as well. Thank you for posting the pictures.

Best,
Terry
 
Hi,

You have to establish what is causing the high Qts.

If its higher than spec Fs, and thus lower than spec
Vas, going with big boxes won't really help that much.

If Vas and Fs are near spec, then the only possibility AFAICT is the magnet
is not fully magnetised, which would be a very very poor state of affairs.

What is the measured Fs ?

With such a low moving mass (for a 6.5") the sensitivity
to suspension variations would be quite high.

rgds, sreten.

Go with the high value Vifa tweeter IMO.
 
Finished

Good evening,
It has been a while---had a little interim construction to do before getting on with the Tang Bands. I ended up trusting my measured parameters. I used the calculators on the Madisound site to calculate about 19.3 L sealed for a Qtc of 1. I cut a 5 in. X 2 in. slot on the back panels, was able to bring the impedance curve down to a relatively flat 18 ohms from 90 Hz down to 45 Hz as the plots show (apologies for the poor quality-I was trying to keep the upload size down). I used hardware cloth stapled on the interior side, and used one layer of 1/4" A/C register filter material obtained from HD. To this layer was added 5 layers of 1/4 in thick very open celled foam I had on hand. These layers were all pressed together and held in place by Hardware cloth.
I went with a BSC as the diagram shows. The reason was--I was trying to simplify if possible--keeping in mind my amp provides about 5 watts max. The tweeter is a piezo. It is a Motorola KSN 1005A, and I can attest along with others who have commented on the internet about piezos--there is a big difference between these and some others I had around. The Motos are hands down better. They are rolled off below 5K. I tried the L Pad/ paralleled resistor circuit and did not like it. I listened for long periods of time and determined the circuit in my diagram is better. It is much smoother, and contrary to my suspicions, very well integrated with the TBs. I found the BSCs allowed the TB to be used out to its limits and also took care of some peaky stuff around 6K. Easy load. Nice deep sounding but detailed bass. Highs are smooth and don't irritate at all. Obviously only one resistor can be used on the BSC, the 16 ohm is just a consequence of my listening/ tweaking. One of the best aspects is the decent efficiency in my room. The dogs there are not suffering from listening fatigue---they are happy.

Terry
 

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