JBL GTx10

[Alex2507]

I wonder if my sub project would integrate well with this speaker.

I tested both drivers and got identical response graphs from a tripod mounted meter on Eddie's coffee table. Nice hole at 50Hz but that's the room. Even Eddie's sub has a mean dip there.

I still need to make a base of sorts for this and a face.
These things weren't exactly light but they're gonna get heavier.

I cranked some tunes through them and vibrated the clip board off.
That tells me bracing is an absolute necessity.

Now I can proceed with both enclosures knowing the drivers are fine. I think I'm gonna like these.

 

[jeffsg4mac]

hmmm! who is that on the TV screen?

 

[Alex2507]

hmmm! who is that on the TV screen?

I was trying for a shot of the bass player for Doug but she was on the screen a lot. From the CD the tune Sinead or whatever, track 8, is absolutely killer. I've been blaring bits and pieces of the DVD at Eddie's cause I can't do that at home ... well, not in good conscience anyway.

I did finally seal the unfinished wood on the inside of the box.

We went from this ...

to this ...

Eddie stayed on the other side of the shop once I broke out the pink paint.

 

[STRONGBADF1]

 

[Alex2507]

So that's what they thought dancing and choreography were back then. That was embarrassing to watch. BTW that vent wall is painted Mauve with a slightly lighter Sweet Pea shading around the edges. Look again, you'll see it.

I've removed the port from the first box, sealed everything up and now need to get back there to assemble the other port, pre drill and dry fit it with 1-1/4" #6 screws. Then remove that port, de-burr everything, apply glue and anchor both ports with #8 1-5/8" deck screws. Then the bracing and base addition begins.

I just got my first pair of progressive glasses a couple of days ago. Doing this with them on is like being on the fast track to getting use to them but it's wearing me out ... but if I tilt my head just the right way I can any thing really really well.

hmmm! who is that on the TV screen?

Sharon den Adel ...

 

[jeffsg4mac]

Sharon den Adel ...

Did I mention she was Hot, Hot,Hot?

Oh and clean the dust off your equipment. It not good to have dirty equipment while watching Sharon

 

[STRONGBADF1]

Did I mention she was Hot, Hot,Hot?

Oh and clean the dust off your equipment. It not good to have dirty equipment while watching Sharon

My lord! I'm sure he cleans his equipment while watching Sharon.

 

[Alex2507]

Oh and clean the dust off your equipment.

It's Eddie's gear. I would say something but it would be a
waste of time and he might throw a hammer at my head.

My lord! I'm sure he cleans his equipment while watching Sharon.

I'm spent.

Check this out. I substitute Sugar for Sinead and the lyrics make perfect sense.

Oh sugar, for the first time
Life is gonna turn around
I'm telling you you will like it, I know

http://www.youtube.com/watch?v=rx-3HGfIRDc

So anyway I'm gonna need to know what to use for acoustic damping in the enclosures and how much and if it's anything other than OC 703 I need to know where to get it. I might need to PM TLS.

 

[annunaki]

So anyway I'm gonna need to know what to use for acoustic damping in the enclosures and how much and if it's anything other than OC 703 I need to know where to get it. I might need to PM TLS.

Check out Mineral Wool Sheets at mcmaster.com They are the semi-rigid sheets at the bottom. Do not get the ones with wire mesh.

 

[Alex2507]

Check out Mineral Wool Sheets at mcmaster.com They are the semi-rigid sheets at the bottom. Do not get the ones with wire mesh.

I can get 8lb mineral wool locally from the same place that has the 703. The prices are $.50/sq ft and $.85/sq ft. I'm considering the 703 if they are in fact interchangeable because they are easier to use in wall mounted sound panels. The 705 is $1.65/ sq ft so the price difference becomes a factor as I would have to buy a bundle of it but I'll get the mineral wool if that's the way to go.

Is covering 50% of the internal surface area with 2" material about right?

I meant I would need a recommendation on where to get that acoustical 'fluff' that I think I remember TLS talking about if that was what he had in mind for me to put in this box.

 

[Swerd]

I can get 8lb mineral wool locally from the same place that has the 703. The prices are $.50/sq ft and $.85/sq ft. I'm considering the 703 if they are in fact interchangeable because they are easier to use in wall mounted sound panels. The 705 is $1.65/ sq ft so the price difference becomes a factor as I would have to buy a bundle of it but I'll get the mineral wool if that's the way to go.

Is covering 50% of the internal surface area with 2" material about right?

I meant I would need a recommendation on where to get that acoustical 'fluff' that I think I remember TLS talking about if that was what he had in mind for me to put in this box.

In speaker cabinets, internal acoustic dampening helps minimize standing waves that happen when sound coming off the back of a speaker cone reflects off internal cabinet surfaces. These standing waves can hit the speaker cone and emerge through the cone, out of phase with the original signal. It can cause interference or even cancellation.

If you plan to use a low-pass filter below about 100 Hz for your subwoofers, this is unnecessary. I don't know the internal dimensions of your cabinets, but I can guess that any standing waves that do occur will be well above 200 Hz. A typical low-pass filter will block the original audio signals that might generate the internal reflections in a cabinet of this size.

I realize that this is against standard wisdom, and it is very easy to say to yourself, I'll line the subwoofer cabinet anyway with something just in case. Go ahead, it can't hurt anything. Just don't go out of your way, or pay a lot, to find the perfect cabinet lining material when it may not make a difference.

 

[annunaki]

For vented enclosures, you will want to cover approximately 25%-50% of the internal surfaces. I would not recommend exceeding 50% though as you can critically damp the enclosure which lessens the point of having a vented enclosure to begin with.

If the sub will be crossed over at 80hz or higher I would recommend using the mineral wool or OC product. This can help ensure that the higher end frequencies remain tamed at higher output levels.

 

[just-some-guy]

i use mineral wool, its pretty heavy stuff. and i get it locally = menards.

idk about anyone else. but i don't want fibers floating around. so i took 2 old flannel pillow cases, put the mineral wool slabs inside them and glued em up. then glued em inside the cabinets.

just sayin

 

[Alex2507]

i don't want fibers floating around

I'm with you. I just looked through your build thread and found one lone pic.
Swerd might be after some compensation for using his avatar as art in your room.

A typical low-pass filter will block the original audio signals that might generate the internal reflections in a cabinet of this size.

I would recommend using the mineral wool or OC product. This can help ensure that the higher end frequencies remain tamed at higher output levels.

Interestingly enough the first two paragraphs in this article addresses and supports both your points and answers the question I had about obtaining polyfill.

I'll find something to throw in there eventually but really enjoy understanding the relative importance of damping verses bracing in the grand scheme of things. I'm not a high SPL sort but the fact remains that any and all showing off is done @ high SPL's so that alone merits some form of itching and scratching ... unless of course TLS comes along and puts his foot down insisting that polyfill is all that's required. It's his build after all.

critically damp the enclosure

I've heard that term a time or two but don't really understand it.

Also I wonder if this from my driver spec's:

P-Vd = 0.35 liters

is the displacement of my driver and should be accounted for in my Vb?

Thanks guys.

 

[just-some-guy]

I'm with you. I just looked through your build thread and found one lone pic.

Swerd might be after some compensation for using his avatar as art in your room.

that is an old, but great, pic. that dlp is my daily viewer now.
i have the projector now. MUCH BETTER !!!
this pic is where it is now. i have toned it down a lot from where it has been.
as i am trying to sell this place.

i think he owes me royalties. i have been rock'n that pic for over 20 years.

btw. dampening and bracing are 2 different things.

 

[Swerd]

i think he owes me royalties. i have been rock'n that pic for over 20 years.

That's a great poster. In the distant past, I had one too, but its long gone. I still have the speakers that were used in the photo.

My claim to that picture is only as an avatar on Audioholics. You, of course, are free to use it in your home as you please - royalty free .

Alex - If TLS Guy said to use polyfill in those cabinets, do what the man says. Standard polyester fiberfill, pillow stuffing, is sold in sewing and craft stores. Parts Express sells something called Acousta-Stuf, in 1 or 5 lb. bags that costs a lot more. As far as I can tell, there isn't much difference between them. I have read that Acousta-Stuff fibers are crimped so that they fill more volume than standard fiberfill.

 

[TLS Guy]

I can get 8lb mineral wool locally from the same place that has the 703. The prices are $.50/sq ft and $.85/sq ft. I'm considering the 703 if they are in fact interchangeable because they are easier to use in wall mounted sound panels. The 705 is $1.65/ sq ft so the price difference becomes a factor as I would have to buy a bundle of it but I'll get the mineral wool if that's the way to go.

Is covering 50% of the internal surface area with 2" material about right?

I meant I would need a recommendation on where to get that acoustical 'fluff' that I think I remember TLS talking about if that was what he had in mind for me to put in this box.

If you are not going to go above 80 Hz, I think you can use Polyfill from Walmart. That is really cheap. However if you buy a lot like I did, then Walmart security may think you are hatching a terrorist plot!

It would not be a bad idea to place mineral wool behind the driver, if you crossover is not fourth order at 80 Hz or below.

 

[TLS Guy]

I'm with you. I just looked through your build thread and found one lone pic.
Swerd might be after some compensation for using his avatar as art in your room.

Interestingly enough the first two paragraphs in this article addresses and supports both your points and answers the question I had about obtaining polyfill.

I'll find something to throw in there eventually but really enjoy understanding the relative importance of damping verses bracing in the grand scheme of things. I'm not a high SPL sort but the fact remains that any and all showing off is done @ high SPL's so that alone merits some form of itching and scratching ... unless of course TLS comes along and puts his foot down insisting that polyfill is all that's required. It's his build after all.



I've heard that term a time or two but don't really understand it.

Also I wonder if this from my driver spec's:

P-Vd = 0.35 liters

is the displacement of my driver and should be accounted for in my Vb?

Thanks guys.

No the displacement of the driver is not accounted for in Vb.

 

[Alex2507]

No the displacement of the driver is not accounted for in Vb.

My question had typo's everywhere.

I meant to ask if that was the displacement of my driver and if I should make my Vb 0.35 liters larger to account for it.

I gotta run but I'll get back to this.

 

[TLS Guy]

My question had typo's everywhere.

I meant to ask if that was the displacement of my driver and if I should make my Vb 0.35 liters larger to account for it.

I gotta run but I'll get back to this.

As far as I can tell from the data in Bass Box Pro, the volume displaced by that driver with flush mounting is 0.078 cu. ft, which you could round off to 0.1 cu. ft if you want.