Need help to develop bass bins

[DeanP]

Hi all,

I need to upgrade my bass bins but there are a few constraints and/or requirements:

> 1.5 cuft (wife dictates this) “no ugly boxes near/at my tv!”
= 10” driver (because of the above)
80 – 250 HZ zone (subs do duty for below 80 HZ)

The ones I have now are 8” drivers which work “okay” but I think I could get away with something a little bigger (box size) without too much complaint from my wife!

My system is made up of Audax drivers, so I found something that may compliment them for a bass bin. The HT240Z0. It is a good price also! I am open to other suggestions for 10” drivers, so please inform me of some others.
So I started to design a box using Unibox404, and I used the manufacturer’s recommended tuning. (well approximately) They suggest 55 HZ tuning for a 45L box, so I opted for the same tuning in a 25L box. This is where I questioned myself as to tuning. I assumed that I choose the correct tuning for my range (80-250) and driver specs. (see attached)
Did I do this correctly?
Is there maybe a better driver for under $60 that would fit my requirements?

[looneybomber]

So just for confirmation purposes,
<80hz is taken care of via your sub(s)
80-250 (midbass) is what you're looking to reinforce
>250hz is taken care of via your mains.

Here's my question, why can't your mains handle the 80-250 area?
How much money are you wanting to spend?
Why not build your midbass bins sealed?
Are you planning on actively powering all of your stuff?

[DeanP]

Here's my question, why can't your mains handle the 80-250 area?

They are Audax mtm's and I have been using bass bins but with an 8" driver and I found that it sounded better. IE: more bass

Why not build your midbass bins sealed?

I could but I'm new to designing ported cabs and wanted someone with more experience to just reassure me that I did in deed develop an "good" cabinet.

Are you planning on actively powering all of your stuff?

Yes, they already are. Bass bins are electronically x-over @ 250hz. 250hz and above goes to my mains and below to my bass bins.

Conclusion:
My main goal for this thread was for someone with more knowledge to let me know that I was using Unibox404 correctly and that I used an okay tuning freq for what my intended goal was: 80-250hz.

[ThomasW]

The Unibox sim looks fine.

Thing is there's no point in having a ported box with an Fb of 55Hz when there's going to be an 80Hz crossover point.

At 80Hz and above the driver will be functioning like it's in a sealed box. At what frequency/power level does your sim show the driver running out of Xmax?

[DeanP]

At what frequency/power level does your sim show the driver running out of Xmax?

Vented: 25L tuned to 55hz - peak xmax @ 84.7hz w/75w
Sealed: 20.7L peak xmax @ 81.7hz w/75w

[DeanP]

The Unibox sim looks fine.

I forgot to says thanks! :T

[ThomasW]

Vented: 25L tuned to 55hz - peak xmax @ 84.7hz w/75w
Sealed: 20.7L peak xmax @ 81.7hz w/75w

Sorry I forgot to ask, what SPL is shown when you hit Xmax? Seems to me this driver may not be a good choice given it's low Xmax

[JonP]

Vented: 25L tuned to 55hz - peak xmax @ 84.7hz w/75w
Sealed: 20.7L peak xmax @ 81.7hz w/75w

Well, there you go... for this woofer in a sealed box, same power handling, slightly lower F3, and higher SAF box size... :T

You might experiment with size for the sealed... going larger than the classic Butterworth (0.707) alignment will lower the tuning somewhat, give a shallower rolloff, and improve the impulse response. (possibly "tighter" bass) The tradeoff will be lower power handling and the bigger box size.

Edit... Thomas' has a point... I didn't read the driver specs either, 4mm Xmax might be a bit small. I got a PE flyer (readable online if you don't have one) and they had a few buyout 10" and maybe another Audax, that might have some more. At least one nameless one had 7mm of Xmax. Check what SPL you're supposed to get and see. Your Audax is very sensitive, maybe it will get loud enough as is.

[DeanP]

what SPL is shown when you hit Xmax?

Vented=113.1db
sealed=107.8db

[rc white]

These are a couple of winisd simulations for comparison.
The most output you can get over this range with this driver is given by a QB 5 II box this has v=30litres, tuned to 69 Hz. (the blue trace is the sealed box).



This needs an auxiliary filter at 78Hz. q=.5

The cone excursion of the QB5 box does not exceed 2mm. at any frequency for 90 Watts of input..

[DeanP]

a QB 5 II box

What is this? Is it some sort of sealed box?

[DeanP]

At least one nameless one had 7mm of Xmax.

I could not find the nameless one but I did find this Audax...
Audax HT240G0
When I tried this in Unibox it looks like it for an open air concept...huge box!

[DeanP]

I played with Unibox404 for the Audax listed above for the enclosure I wanted with the tuning peak to 9db. Below is what I got, doesn't even max out the xmax.
Max spl=117.3 @ 95.5hz
80hz=113.8spl
250hz=109.6spl
all with 75w input.
What do you guys about this one?

[rc white]

What you have there is basically a QB5 box with no auxiliary filter.
If you already have an electronic second order filter in the system at around 80Hz. you can use it as part of of a filter assisted reflex alignment known as a QB5 II. These are much used in professional sound reinforcement and will give maximum output.

[DeanP]

What I do is use an electronic x-over @ 250hz: 250hz and below goes to bass bin; 250hz and above goes to mains. My reciever is set to "small" mains so as to x-over at 80hz to my subs. Works well but I would like more 80-250: thump,thump! I think the above audax(HT240G0) might work. I would like some other opinions though.

[looneybomber]

10" Dayton RS270?
What's your budget?

[DeanP]

I've decided to get two Dayton SD270s. They look like they will work perfect for my situ. I gonna make a sealed box. ~24l.
Now I was reading Bent's thread about stuffing for his sub. For my situ, being a bass bin for 80-250 hz, what would be recommended for stuffing/damping material?

[ThomasW]

Plain old fiberglass batting

[DeanP]

Thanks Thomas. :T

[DeanP]

I'm dragging up this old thread as I've had a couple of questions...

My gainclone is causing thumps when I turn it on or off and I don't feel like fixing it right now.
So I was wondering if using a plate amp would be okay to drive the bass bins; one each bin. I was wondering if the x-over would be okay at 180hz in stead of the 250hz I use now? Would it still take the load off of the mains?
I would use the high level inputs and then the high level outputs to the main speakers.

[DeanP]

Hi!

I was wondering if someone could answer my question as I am still wondering if 180hz is still okay for a bass bin...
Thanks in advance... :T

[ThomasW]

No problem...

[DeanP]

Thanks! ThomasW. :T

[DeanP]

Well I figured out my problem with my gainclone amp; it was my electronic cross-over. If I power up the x-over before and shut it off after the amp, then it resolved my problem. This makes things easier now as I don't have to use any plate amps!
Now I just have to figure out how to power up the x-over before the amp turns on and how to shut it off after the amp powers down. I'm thinking some sort of remote control switch for the x-over. With my Logitech remote, I should be able to delay the amp and then delay the x-over...back to the drawing board.
Thanks ThomasW for chimming in when I thought I had no choice but to use plate amps.

BTW I have a new Reciever coming:Yamaha RX-V663. So everything will go thru hdmi.