frugel-horn flat pack; what do you think?

rogerfederer

Junior Member
Would just buying a few cheap pillows from Walmart and putting them at the port reduce the bass output any? Typically they’re pretty well filled and only $3 a pop or something like that. Just thinking out loud
i'm going to try the panty hose idea. 1 pair hose and some cotton filling, i'm probably in for $10 or so.
 

Thermionics

Post Whore In Training
I'm with Roscoe - if the CHBs sound good (albeit bass-shy), then perhaps the answer is to go with the CHBs + sub (and maybe down the line a super-tweeter if you are so inclined) and save the Alpairs for a different cabinet.
 

rogerfederer

Junior Member
I'm with Roscoe - if the CHBs sound good (albeit bass-shy), then perhaps the answer is to go with the CHBs + sub (and maybe down the line a super-tweeter if you are so inclined) and save the Alpairs for a different cabinet.
like most of y'all i have lots of speakers (many more in the garage) and limited space. i love the idea of having horns that can run 2 drivers i'm interested in. will try the ingenious panty hose idea and see if that works. if so, then i can swap between the 2 sets of drivers by swapping in and out the supra baffles that have the drivers already attached. would need to remove the panty hose/cotton things for the CHBs and could go to the flea decware watt amp as well.

next i need to make some OBs for my zenith CZs that are boxed up in the garage ....
 
love the panty hose idea! i can get cotton batting at joannes. OK, will try that. thanks!
I hadn’t been paying close enough attention; I didn’t realize you didn’t have any stuffing in the front chamber. I believe only drivers with rising response (CHB, Fe126) can get away with no stuffing.

I would use the stocking trick but use polyfill pillow stuffing instead of cotton batting. It will tease out better and hold its shape better. You’re only putting about an ounce of stuffing in so you want it to be able to fill the space.
 

rogerfederer

Junior Member
I hadn’t been paying close enough attention; I didn’t realize you didn’t have any stuffing in the front chamber. I believe only drivers with rising response (CHB, Fe126) can get away with no stuffing.

I would use the stocking trick but use polyfill pillow stuffing instead of cotton batting. It will tease out better and hold its shape better. You’re only putting about an ounce of stuffing in so you want it to be able to fill the space.
i have a bunch of excess pillows. can i just rip one open and use the filling? or should i go to joannes?
 

rogerfederer

Junior Member
Progress and setback
got the pantyhose and polyfill. stuffed one cabinet. then, couldn't get one of the bolts out to remove the supra baffle from the 2nd cabinet. finally got the offending bolt and nut out and off to the hardware store to see if they have this. otherwise will have to ask bob for another one.
 

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rogerfederer

Junior Member
luckily lowes to the rescue; found replacement bolt and nut. stuffed the 2nd cabinet w the polyfill hose and buttoned it up. maybe the bass is a bit more muted and bit more articulate? will listen over the next few days with a variety of music.

the good news is that the alpairs are impressive drivers and produce a decent amount of bass, something i did not expect with these cabinets.
 
My initial impression when you showed the filled stocking is it seems a bit compressed. If you could, I would try to have a looser bundle. It looks like you may have filled to the toe. I maybe would look at using the thigh/hip section and knot off the lower section.
 

rogerfederer

Junior Member
My initial impression when you showed the filled stocking is it seems a bit compressed. If you could, I would try to have a looser bundle. It looks like you may have filled to the toe. I maybe would look at using the thigh/hip section and knot off the lower section.
what is the advantage/likely effect of a looser stuffing?
 

JP

Junior Member
I don't think the hose idea is going to work well. It's too compressed and the corners of the chamber will be void.
 

rogerfederer

Junior Member
I also have these
they are mesh bags my wife used to put delicates in the washing machine
i could fill them loosely with polyfill and use them instead of the panty hose
 

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EDIT: I was writing my long-winded reply when Roger posted his comment. We are on the same page.

You want the stuffing to fill the void as evenly as possible. With your smaller stuffing sausage, it appears as if you will have some unfilled spaces, mostly in the corners and in the lower section of the expansion chamber. Since we have the pillow stuffing already and you seem to know how to get to Joanne’s, maybe you should just make a pillow custom fit to the chamber?

My approach would be:

1. Create a paper pattern based on the section of the horn to be filled. It should look like a tall, truncated right triangle solid that would fill the horn perfectly. I would increase the dimensions by 1/4” (h x w) to assure it is gently compressed when installed.

2. I would use very light nylon mesh. It may be used for filter fabric and is usually slightly stiff and see-through. You should be able to breathe through it as easily as grill cloth. Cut the cloth to your pattern and sew into the pillow shape. It doesn’t have to be pretty but it should be strong enough.

3. The pillow doesn’t need to a top; the stuffing will stay put without one. Leave the top open like a paper grocery bag. I would sew a Velcro strip to the top so I could attach it to the enclosure behind the driver. I would also include a safety string in case the pillow slides to the bottom of the enclosure and you need to retrieve it.

The plans call for 20-40g of stuffing. I would listen to the speakers in their intended locations first with no stuffing. I would then load the full 40g of stuffing to get an idea of what maximum damping sounds like. I would remove the pillows/bags and remove the stuffing. Weigh out 20g and evenly fill the bags, paying careful attention to the corners. Install the stuffing bags and test. You can now remove the driver and add another 5g (25g total) from the top, reinstall the driver and test. Repeat 3 times until you have used the full 40g of stuffing. Decide which version sounds best to you and revert to that stuffing load.
 

rogerfederer

Junior Member
roscoe,

i appreciate your idea but that kind of sewing is not really in my quiver of arrows. the cavity actually widens at the base making sewing such a pillow tricky.

i have already listened to the speakers with the current level of stuffing for a week. that is why i am trying to tame the boomy bass.

i think i'll see how the pantyhose approach works for a day or so. then try the mesh bags.

many thanks,

doug
 

rogerfederer

Junior Member
Here are the diffusion panels leaned against the wall.
Immediately the mids/top seem a bit cleaner, so maybe they have taken out some fuzz that was previously in the mix. there is still a rumbly, inarticulate very low bass note left in what i've heard so far (maybe 1/2 hr). working in my study now but will listen more later.
 

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rogerfederer

Junior Member
did some reading re diffusion v absorption v bass traps. in one thread someone suggested stuffing the port with a soft cloth so i have tried that. reduces the boomy a bit more. maybe what is left is from inside the cabinet which takes me back to the stuffing issue.
played around a bit with moving them out and them back in, 1 diffuser behind each instead of 2. will continue to experiment.
 

rogerfederer

Junior Member
and the saga continues: one of the alpairs has developed a buzz. it started a few days ago. i took the driver out and adjusted the cap on the back and it went away. but came back today with a vengeance and fiddling w the cap didn't solve it. have emailed mark audio and madisound for advice. if they don't have suggestions i could send to gordonw who seems to be able to bring drivers back from the dead.

i put the corals back in and had no trouble fishing out the pantyhose legs stuffed with polyfill. nice to have options:)
 
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