Design modification assistance needed

[googler]

Hi everyone, I am currently building Zaph's Vifa XG18 / Seas 27TDFC MTM. Due to WAF I had to go floorstanding but want to keep the midbass control from the sealed cabinet. If I stay sealed, I am going to have a good portion of unused space in the bottom of the "box" and am thinking about adding a sub or two.

Here is the link to Zaph's design: Zaph's MTM design

I have already purchased the components/drivers, so changing the MTM portion of the design would not be desirable

The cabinet that I have almost completed (all sides finished just not assembled) is curved. The basic shape would be an elipse (outside only, internal is a trapezoid) with an 8.5" baffle. Given the curved sides it would be a major challenge to make the subs side-firing or powered.

So here are the questions:

Are there any 8" sub drivers that would provide enough bass for HT that would be happy in a 1ft^3 sealed enclosure?

Do I need to modify the crossover of the current design to integrate the subs with the midwoofers?

Thanks for the help. I am sure to have more questions coming as I haven't assembled the x-overs yet

[googler]

ok, maybe I am asking for too much. I don't think that I will be able to find an 8" woofer that can beat the 34hz f3 of the XG18's...

Are there any suggestions as to what I should do with the space in the cabinet? TL?

[googler]

OK. I am leaning towards the TBW8q-1071 found here PE TBW8Q

According to WINisd, which I don't really know how to use, two of them would fit in a 1.2 ft^3 sealed enclosure. I want to have separate input to the box for these so they can be on individually amplified. What do I need to do for crossing them over or EQ etc?

Anyone?

[rabbitz]

Having subs in the bottom of the enclosure is not a real good idea as vibrations can upset the higher frequencies due to their short wavelength.

I'd try the the speaker vented and sealed to see which you like the best and don't dismiss the vented outright without hearing them. A vented design should provide ample bass with those woofers.... not HT bass but heaps for clean music.

If you have the need to put something in the unused space, use some lead shot or dried clean sand to add mass to the speaker. Other than that, forget about the space and pretend it's not there.

[chainenoble]

i also will build this design-i allready have the tdfc and was looking for a good design for them as the tdfc is a fantastic tweeter-will order the woofers on monday.have you built the crossover yet? do you know how to get a .1 ohm resister and what does zaph mean by "resistor part of the inductor" ?


glen

[playazinc]

the .1 resistors dont exist they are just notation the cad software uses to show the resistance of the inductor, just forget about them.

[Cal Weldon]

If you haven't yet bought the woofers, you might consider this one from TB. I've had good luck with them and the graph seems a little smoother. Cheaper also. They don't have the greatest efficiency but if you throw in a plate amp like I have...

Cal

http://www.tb-speaker.com/detail/1208_03/w8-740c.htm

[Zaph]

Thanks for choosing one of my designs. If you need any assistance, post right here. If I'm unavailable to help you, I'm sure someone else can.

The 8" TB Cal mentioned is very nice for the price. Also consider the 8" Peerless XLS, in a vented 1 cu ft box. Its nearly twice the price and roughly the same output, but offers lower distortion. I'm building a sub with it right this moment. Nice little sub. Let me know if you want more accurate T/S parameters than Peerless gives you. (they are off a bit)

And finally, here's a really good option for 1 cu ft sealed: Peerless 10" XLS, using an amp with boost. The Parts Express 150 watt plate amp has 5db boost at 30hz, perfectly offsetting this woofer's early low Q rolloff. OR if, they still have them MCM has nearly the same thing for $50. (here) Just set the crossover to 160hz, and then us an external active crossover at about 100. Alternatively, you may be able to just run the XG18's full range and set the plate amp crossover to 50 hz, but an external sub crossover such as one included in a HT receiver will sound a little better. A couple of these plate amps and peerless 10's will probably shock you with their output.

If you can somehow work 1.5 cu ft into your enclosure, the new Vifa metal cone MA26's are a better choice yet. (no boost needed for these)

Good luck,
John

[chainenoble]

zaph,any idae how this mtm would work with the lcy110.i have a couple lcy110 and have been looking for some affordable woofers to pair with them.these woofers look real good-what do you think? i also have a couple tdfc's incase the lcy110 don't work.

p.s. i have the ma26 in 1.5 cuft with a 300w plate amp.it's a great sub

[adolphe]

I was just wondering if anyone involved or following this thread has finished their design? I talked to Zaph earlier this week about doing something similar, but I had not found this thread yet. I was thinking about the MTM with a 10" Aurum Cantus woofer. Zaph suggested the 10" Peerless XLS, and now I'm starting to maybe think the 8" would be fine.

Anyone have any thoughts?