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Multi-Way Conventional loudspeakers with crossovers

Help with HiVi F8 Project
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Old 17th July 2008, 06:36 AM   #11
pp173 is offline pp173  United States
diyAudio Member
Join Date: Jul 2008
Thanks again for everyone's help. I just want to be clear I'm using the Wt3 correctly, and see if its' readings make sense.

Re = 6.587
Fs = 38.36
Qts = 0.4685
Qes = 0.5067
Qms = 6.223
Le = 0.6176
Mms = 24.86 g
Vas = 1.563 Cu Ft (43.4946L)

I selected "Measure Free Air Parameters" while the woofer was free standing. I removed my port, sealed the hole, mounted the speaker, entered the volume of the encloser under Vb in "Test Box Method", and selected "Measure Vas".

It's calling for a 44L vented enclosure. This seems a little off from the 19L on PartsExpress website.

Am I doing something wrong?

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Old 17th July 2008, 10:45 AM   #12
sreten is offline sreten  United Kingdom
Join Date: Nov 2003
Location: Brighton UK
Hi, data sheet specs, /sreten.

edit : your specs indicate a 35L sealed box for Q=0.7.
As usual vented is ~ double this at 70L, which is a big box for an 8".
The major discrepancy between specs is Mms and Qms.

Mms depends on assumed Sd and is explainable. Qms is not
quantifiable: 1.7 HiVi spec is low and 6.2 your spec is high.
This is making the modelling difference, Qts = 0.38 or 0.46.
And doubling box sizes ..... due to venting /sealed boundary.
(Qms is easy to fudge in a spec sheet for wanted Qts)
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Old 17th July 2008, 05:04 PM   #13
cidd is offline cidd  Norway
diyAudio Member
Join Date: Jul 2008
Hello guys! Im new here, and i hope its ok for me to "borrow" your thread a bit pp173.

I have the F8 too, and i was thinkin about building a closed cabinet for it. Does anybody know what volume I should build? And what about isolation and stiffening inside the cabinet?

My project:
Im building a sub with 2xCV 10" sub, and two satellites with the F8's and Seas 27TBCD/GB-DXTSeas 27TBCD
I have cutted off the sub at just over 150 hz, and im using a 2-way filter at 2.2 khz (12 db/oct). Well, i havent buildt the cw's yet, but this i s my plan so far anyway.
Is it a problem that both the sub and the F8's are playing under 150 hz?

Just give me your comments.

And also, im very exited about what you discovers with your new measuring tool, pp173.

Excuse my bad english guys, im from Norway
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Old 21st July 2008, 08:53 PM   #14
pp173 is offline pp173  United States
diyAudio Member
Join Date: Jul 2008

The F8's put out a decent DB level in the lower freq. range. I'll start out by saying again that I'm very new.... But, in my experience with them, I've not felt as though I needed a subwoofer. Though, you may want to implement one to increase power handling, I guess. Depending on who's specs you look at, the F8 may only handle 60W RMS. Since I'm listening in an environment that's not very large, this works for me.

The other thought I can share with you may end up changing as I iron out my enclosure (speaker measurement) issues...

While the F8's response seems to stay flat beyond 1Khz (it has a recommended crossover freq. between 1.8 and 2.2Khz), I don't find it's mid-range performance to be that great. The sounds come across as being sharp and unclear (but not, necessarily distorted - just imbalanced).

As such, I'd like to cross over at 500Hz. But, again, this may change once the enclosure is working with the speaker the way it should. I didn't start this wanting to build a 3-way... So, I'm hopeful I can clear things up.

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Old 22nd July 2008, 03:46 AM   #15
cidd is offline cidd  Norway
diyAudio Member
Join Date: Jul 2008
First of all, sorry for my typing mistakes in the previous post. I cant find any Edit button..

Im a little bit dissapointed when i hear that F8 has a bad mid range performance. Im going to cross it at 2.5 khz, and i cant afford going any lower, because my tweeter cant handle that. And also it is quite a braintwister for me when you say that F8 only can handle 60W. My amp (nad 218) delivers about 2x200W in 8ohm, and my plan is to let the nad drive all of my speakers (2 sat's + sub).

Maybe it would be wise to buy an ok int amp, and run the sat's at that one, and let the nad take care of the sub only. But i think that would be a little bit overkill.. =p

Is it a general opinion that the F8 does'nt perform well in a 2-way speaker?

Today i built a 31 L cabinet for the sat. Are you recommending any use of isolation? I think im going to stiffen up the cabinet with some bars at least.

As you can see, this is more or less a shot in the dark right now for me. Maybe it will work out fine, maybe not (= Let's hope the latter.

And how's the measurements going with your new equip, pp173?
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Old 22nd July 2008, 05:17 AM   #16
pp173 is offline pp173  United States
diyAudio Member
Join Date: Jul 2008

Still waiting back to understand if my WT3 is working properly. Until I understand that, I really can't comment as to the size of your cabinet (nor would I be the best person to).

I wouldn't go that high in freq. to the F8. Swan recommends a crossover point between 1.8 and 2.2Khz. So far, my preference would be for the lower end of that range. But, like you, I don't have tweeters that can support it.

I did plug the values I collected into Winspeakerz. Ironically, it recommended a box size similar (1" off in height) to something I had already experimented with. It also recommended dual 2" ports as opposed to my single 3". I blocked up my 3" port, cut and populated the two 2" ports, and installed the crossover and drivers.

I have to say the overall sound is much more even and pleasing. This seems to be at the expense of a little low-end punch. But, the net outcome is much more satisfactory.

Even so, I'm going to hold off on constructing a new pair of cabinets until I know for sure my measurements are accurate.

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