CC Conceptualizing

[Adam_G]

I've been throwing around the idea of a WmtW CC, with the mt stacked, woofers on either side. The thing is, it's a pretty low budget build. I'm not shooting for ruler-flat response, just something fun to play with. It will be paired with a sub from ~90hz down, but I as shooting for a decent response down to about 70hz.

The drivers as they stand:
Woofers x 2: Aura NS6
Mid: Vifa TC9FD
Tweeter: Vifa BC25SC06

Yes, I know a $60 woofer and $70 tweeter would probably perform better, that's not the point :p

I'm shooting for good response up to 30degrees, but the mid gets very sketchy in the upper range off-axis, which is why I've got the BC25.

My ballpark response idea:
Woofers from 60-300hz, with a gradual roll-of. They will be in a sealed box sharing around 2cf, or that's how it sits now. The TV will sit on top of the CC.
The mid comes in probably around 350/450, going up to ~5000/6000, and the tweeter joining in on a gradual slope up high to fill in.

Unfortunately, I don't have any testing equipment, so it's essentially going to be a fully simmed response on my end.

I have played in x-over 3, but haven't gotten into PCD7 yet. It's pretty intimidating when you first look at it.

I'll add-on with some early x-over 3 sims and let you tear them apart for me. Any useful tips/tricks such as series/parallel on the woofers and if I should reverse polarities on mid/tweeter/both would be helpful.

As it stands, the drivers cost right around $50 all together, I'm looking to keep the build under $120 for drivers+x-over

[WernerM]

Re: CC Conceptualizing

Adam,
This could turn out to be a nice sounding CC. The only recommendations that I would make are target your XO points closer to 500Hz and 3500Hz. I am using the TC9 in my TMWW and I honestly don't think it will be happy down around 300Hz. YMMV, and that is just my humble opinion.

[[email protected]]

Re: CC Conceptualizing

haven't ran any numbers but 2cf seems a bit big.
maybe later chris will stop by. this is the kinda thing 'he do well'.

[donradick]

Re: CC Conceptualizing

Using that arrangement, of the tweeter over the mid should provide a great off-axis response, probably even
greater than 30 degrees. I'm pretty sure WernerM used that mid in his 3 way, so his crossover for that will
be a good starting point for the mid-woofer crossover point, but you want to let yours go higher than (I think)
he did.
I agree with Arlis, 2cf is too big for what you need. Use Unibox to model, I'll bet around 1.3 cf sealed will give you a rollof
around 80 Hz. I haven't heard that mid yet, but I know you'll like the other drivers.

[Adam_G]

Re: CC Conceptualizing

@ Werner: That's very doable. I wanted to keep it below the lower male voice reaches, but I was worried about the low end on the mid, so thanks for the heads up!
@ Arlis: If it's too big I can reduce the chamber size by putting in a false back or something. The dimensions I was guestimating with were 8" tall, 24" wide, 18" deep external, figured 3/4 material, separate volume for the mid/tweet and woofers. When I looked at it in unibox the NS6 had very low power handling in the 2cf, around 15w, so it's probably better to go with the false back.

[Adam_G]

Re: CC Conceptualizing

@Don: I have built the maurbacs for a friend, which is why I like the NS6, but I felt the vocals weren't exactly what I'm looking for in a CC. For music they're great, but I'm looking for a little more in the spoken word clarity for tv/movie use.

[WernerM]

Re: CC Conceptualizing

@ Werner: That's very doable. I wanted to keep it below the lower male voice reaches, but I was worried about the low end on the mid, so thanks for the heads up!
@ Arlis: If it's too big I can reduce the chamber size by putting in a false back or something. The dimensions I was guestimating with were 8" tall, 24" wide, 18" deep external, figured 3/4 material, separate volume for the mid/tweet and woofers. When I looked at it in unibox the NS6 had very low power handling in the 2cf, around 15w, so it's probably better to go with the false back.

The nice thing about your choice of drivers is that the NS-6 doesn't sound bad in the mid range frequencies. You need to take into consideration the TC9 needs its own space when thinking about the box dimensions. IOW that box may be okay once you add a separate internal chamber for the TC9. Once you figure out how much space to give the TC9, subtract that volume from your overall box, and that is the volume for the woofers.

[WernerM]

Re: CC Conceptualizing

IIRC I read some where that the box size for the mid chamber should be tuned for 1 octave lower than the crossover. I may be mistaken though. If I'm not, then I would model it in Unibox for a sealed alignment tuned to 250Hz (if shooting for a XO of 500Hz). Someone please correct me if that is wrong.

[Wolf]

Re: CC Conceptualizing

Several schools of midrange thought here:
-largest midrange enclosure possible to allow the driver to naturally emit midrange uninhibited, up to and including open/TL/dipole.
-Use the optimal sealed box alignment for 0.707 Qtc, even though it won't be reaching low.
-Use the box rolloff in conjunction with the highpass to get the rolloff you want.
-Use 'what fits' and compromise or adapt the design to suit this compromise.
-use a dome-mid, sealed-back mid, or chambered mid and go with the flow.

Those really are your only options.
Wolf

[Adam_G]

Re: CC Conceptualizing

My plan is to have the mid in its own chamber, but I haven't modeled how much volume that particular mid would like quite yet. I figure it won't be too much, and I will still need to limit how much volume the NS6 has in order to increase the power handling. I've got ~3cf total, I figure the mid won't take much, and if the two NS6 take around 1.3cf that'll leave me with an extra chamber in the rear with no speakers just to leave enough box to support the TV.

[johnnyrichards]

Re: CC Conceptualizing

My plan is to have the mid in its own chamber, but I haven't modeled how much volume that particular mid would like quite yet. I figure it won't be too much, and I will still need to limit how much volume the NS6 has in order to increase the power handling. I've got ~3cf total, I figure the mid won't take much, and if the two NS6 take around 1.3cf that'll leave me with an extra chamber in the rear with no speakers just to leave enough box to support the TV.

I'm sorry, but that is quite *** backwards.

[WernerM]

Re: CC Conceptualizing

I'm sorry, but that is quite *** backwards.

Johnny,
Could you elaborate a little? This is an area that I need more clarification as well.

[[email protected]]

Re: CC Conceptualizing

I'm sorry, but that is quite *** backwards.

I think what Johnny means to say to the OP is, "Why build a speaker box larger than it needs to be with an empty chamber at the back, when you could eliminate the extra empty chamber and just build a shelf above the CC speaker to hold the TV?" Building a separate shelf above the center channel speaker to hold the TV would be my favored approach, since that way you'll have a speaker enclosure that is compact enough to use in other applications, not just for holding up the TV without a shelf.

$.02

[Sidi]

Re: CC Conceptualizing

I don't see any problem with people building speakers into their room as furniture. People make decorative end table subs, coffee table subs, etc.

[Adam_G]

Re: CC Conceptualizing

It's simple enough I thought, you build a wooden box to set your TV on, it just happens to have some speakers in the front... The speakers don't want a box that big on the inside, you cut the volume down. The outside dimensions are set to look good. It's furniture + speaker. Just like Sidi said. If it ever came down to it I could realistically cut the extra chamber in the back off if I ever wall-mounted the TV, but seeing as I rent the house it's doubtful that I would do that in the near future.