I crossed the M22 between 100Hz-130Hz as I wanted it for bass only and have very little mid contribution so not to interfere with the great mids from the 18W8531. The baffle width on mine was 320mm.
The Vifa info recommends a max crossover of 500Hz but I imagine that's with a 2nd order xo, so for a 1st order I'd use a max of 250Hz.
I used a 5.6mH (0R25) inductor with a zobel using 33uF + 10R to make it drop rapidly so it was down >20dB at 1kHz.
Generally with a 0.5 woofer, I've found it best to crossover at around a third of the baffle step frequency, otherwise the BSC effect seems to much as the summing adds too much past the baffle step frequency. With my low 100Hz xo, the 0.5 woofer is still adding around 2.5dB at the baffle step frequency and 1dB at 1kHz. In your case with a 280mm baffle for a similar effect that would be around 137Hz.
That is lower than I would have thought, but your explanation make good sense, thanx rabbitz.
SWMBO should get her bedroom speakers soon
SWMBO should get her bedroom speakers soon
Finally had a chance to start cutting after a full-on Christmas.
Was all smooth sailing until I realised that one of the measurements on my box diagram was incorrect. Rather than re-cut the top and bottom of the boxes to the correct depth, I've decided to rebate the 1st half of the doubled up baffle, I'll lose a bit of volume but it should be fine according to the software.
Is there any reason for me to not rebate the woofers into the baffle? I prefer the flush look to having it sit proud.
Was all smooth sailing until I realised that one of the measurements on my box diagram was incorrect. Rather than re-cut the top and bottom of the boxes to the correct depth, I've decided to rebate the 1st half of the doubled up baffle, I'll lose a bit of volume but it should be fine according to the software.
An externally hosted image should be here but it was not working when we last tested it.
Is there any reason for me to not rebate the woofers into the baffle? I prefer the flush look to having it sit proud.
Getting there slowly. I've mentioned this whilst building my 2-ways but here it is again... Why is it that when you decide to take on a new project that you suddenly don't have time to work on it?
It's not all bad, New Year's day I'll be on a fishing charter off the east coast of Tasmania so I can't really whinge.
Decided that I'll make the rebated panel the rear of the enclosure. It would of been too fiddly to line up the doubled up baffle correctly. Laminated the baffle today also.
It's not all bad, New Year's day I'll be on a fishing charter off the east coast of Tasmania so I can't really whinge.
An externally hosted image should be here but it was not working when we last tested it.
Decided that I'll make the rebated panel the rear of the enclosure. It would of been too fiddly to line up the doubled up baffle correctly. Laminated the baffle today also.
I have a few questions that I hope someone can answer for me.
1. I am able to get my hands on some "pink bats" used to insulate the ceilings in houses. I can get it for nothing, is this a suitable dampening material. I've handled it before and understand that it is a fairly horrible substance, but once sealed in an enclosure, would there be anything to worry about?
2. How much dampening should I be using? I have enough material left over to make a double holey brace so that is what I have started to do. Should I fill the box to the brim? I understand that this is usually done to taste, but I have too little prior experience to know what I like. My aim is to get the speakers to produce bass as low as they realistically can.
3. Is gluing the braces in place adequate for strength, or should I also screw/nail them in place?
4. Should I line the internal walls of the enclosure with felt/foam?
I'll get some pictures soon showing the progress of the enclosures, they are getting quite heavy now.
1. I am able to get my hands on some "pink bats" used to insulate the ceilings in houses. I can get it for nothing, is this a suitable dampening material. I've handled it before and understand that it is a fairly horrible substance, but once sealed in an enclosure, would there be anything to worry about?
2. How much dampening should I be using? I have enough material left over to make a double holey brace so that is what I have started to do. Should I fill the box to the brim? I understand that this is usually done to taste, but I have too little prior experience to know what I like. My aim is to get the speakers to produce bass as low as they realistically can.
3. Is gluing the braces in place adequate for strength, or should I also screw/nail them in place?
4. Should I line the internal walls of the enclosure with felt/foam?
I'll get some pictures soon showing the progress of the enclosures, they are getting quite heavy now.
Pink batts are fine, but you can use a little polyester just behind the driver as well. if sealed fill the boxes
Glue is fine
Foam or felt just behind the driver can be a good idea but shouldn't be needed if filling the full volume with fiberglass.
if ported the felt behing the driver on the wall and a 2 inch layer of glass on the walls
Glue is fine
Foam or felt just behind the driver can be a good idea but shouldn't be needed if filling the full volume with fiberglass.
if ported the felt behing the driver on the wall and a 2 inch layer of glass on the walls
Nasty stuff and have read that it can get into voice coils but have never experienced it. I had a pair of NS10Ms (100% fibreglass batt filled) for almost 25 years and never had a problem.
OK for fully sealed but do not use on vented designs as you can get the fibres coming out of the port which will contaminate the area.
OK for fully sealed but do not use on vented designs as you can get the fibres coming out of the port which will contaminate the area.
Haha, don't need to convince me at all, I can still remember handling the batts from years ago, itchy stuff. Was even wearing protective full body clothing and it still irritated me.
My plan is to use the pink batts right up to the front of the enclosure, then put a layer of the left over dampening from my bookshelf speakers in between the driver and the fibreglass insulation just for peace of mind (though you've now given me evidence to not be overly concerned about it). The left over dampening is acrylic, I think I just have enough for both boxes.
Here are some pics of current progress.
Sorry for the dull/dim pictures, should of taken them in better light. The last picture is just a mock up of the holey brace, trying to get the brace sitting snug on the speaker magnet, takes a fair bit of fiddling. I decided to screw the baffle on due to not having enough clamps or adequate weight to sit on top of the box. They have been countersunk and will be hidden by the veneer.
I'll just add that buying a decent safety mask has been a wise investment, I'm not unfamiliar with MDF but I still can't get over the mess it makes whilst routering.
My plan is to use the pink batts right up to the front of the enclosure, then put a layer of the left over dampening from my bookshelf speakers in between the driver and the fibreglass insulation just for peace of mind (though you've now given me evidence to not be overly concerned about it). The left over dampening is acrylic, I think I just have enough for both boxes.
Here are some pics of current progress.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Sorry for the dull/dim pictures, should of taken them in better light. The last picture is just a mock up of the holey brace, trying to get the brace sitting snug on the speaker magnet, takes a fair bit of fiddling. I decided to screw the baffle on due to not having enough clamps or adequate weight to sit on top of the box. They have been countersunk and will be hidden by the veneer.
I'll just add that buying a decent safety mask has been a wise investment, I'm not unfamiliar with MDF but I still can't get over the mess it makes whilst routering.
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If the pinkbatts are too unpleasant, I've used this polyester based stuff from Jaycar:
650gsm Acrylic Speaker Dampening Material - Jaycar Electronics
I used it to damp a sealed midrange in a three-way system. It works pretty well and sheds much less than batts do.
Cheers,
AJ
650gsm Acrylic Speaker Dampening Material - Jaycar Electronics
I used it to damp a sealed midrange in a three-way system. It works pretty well and sheds much less than batts do.
Cheers,
AJ
I have found that both Acrylic and polyester work well as a dam in front of the fiberglass but that the fiberglass seems to act better in damping the box and making it appear "Bigger" I tend to salvage the polyester from excess air-conditioning ducts and saving it for projects
On completion of the last sealed-box speaker I built, my wife made me promise never to use fibreglass fill ever again! Or bring it into the house. Or near the house. Or the garage. And throw away any clothes that have come into contact with the fibreglass ... it was messy! 😀
I use that stuff in most of my speakers. Easy to use in sealed or vented and works well.... plus no itching.
Thanks for the input.
Perhaps my hyperlink was missed but the Jaycar product is what I used on my first set of speakers. The main reason that I am using the pink batts is because we have a couple of full bags left over from when my parents' house was built, so it's one less thing I have to buy.
Perhaps my hyperlink was missed but the Jaycar product is what I used on my first set of speakers. The main reason that I am using the pink batts is because we have a couple of full bags left over from when my parents' house was built, so it's one less thing I have to buy.
I'm back from a break and looking to get this project going. Few more questions before I start ordering 🙂.
Was this XO design for either the Treols or HHH type floor stand design or a bookshelf?
What sort of difference in sound would I be expecting from a bookshelf to a floor stand?
Would pictures of the room where speakers will go help pick a design?
Cheers for all the help.
The xo is designed for Troel's floorstander.
A vented floorstander would generally give better bass extension as well as more body to the sound over a bookshelf. With a bookshelf you still need a speaker stand which has the same footprint as the floorstander plus good stands can be expensive.
Using the PL18 driver in a bookshelf is a bit of a waste as it only needs a bit more volume for a floorstander. Usually you have bookshelf speakers between 8-15 litres and anything beyond is usually a floorstanders. Large bookshelf speakers don't make sense to me unless there's a particular application where it's desirable. I have used larger mid woofers in under size enclosures to suit particular applications.
A vented floorstander would generally give better bass extension as well as more body to the sound over a bookshelf. With a bookshelf you still need a speaker stand which has the same footprint as the floorstander plus good stands can be expensive.
Using the PL18 driver in a bookshelf is a bit of a waste as it only needs a bit more volume for a floorstander. Usually you have bookshelf speakers between 8-15 litres and anything beyond is usually a floorstanders. Large bookshelf speakers don't make sense to me unless there's a particular application where it's desirable. I have used larger mid woofers in under size enclosures to suit particular applications.
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Have glued the braces in now. Had a bit of trouble burning the wood with the hole saw at first but I managed to get over that small hurdle.
Most likely made some mistakes, I just tried to mix up the holes where I could, make it a bit more random. Tried to have a bridge behind where the brace contacts the speaker magnet. I've left enough room behind the basket to need to use some rubber/foam/cardboard as I didn't trust myself enough to have the brace butt up tight.
I'm awaiting the speaker terminals and then I can get the back panel glued in.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Most likely made some mistakes, I just tried to mix up the holes where I could, make it a bit more random. Tried to have a bridge behind where the brace contacts the speaker magnet. I've left enough room behind the basket to need to use some rubber/foam/cardboard as I didn't trust myself enough to have the brace butt up tight.
I'm awaiting the speaker terminals and then I can get the back panel glued in.
Have a quick question regarding the speaker terminals.
I immediately regretted my decision to buy speaker terminals mounted to a plate rather than just individual ones when I received them this morning.
I like the way they look, but I need to cut a chunk of material out of both back panels to accommodate them. Will these negatively affect the sound of the enclosure? Will they be fine as long as I fit it snuggly and make sure it's air tight? Will the rigidity of the rear panel be ok with the material I have to cut out of it? I'm planning to mount them off centre between the holey brace running front to back, and the corner of the box.
I immediately regretted my decision to buy speaker terminals mounted to a plate rather than just individual ones when I received them this morning.
An externally hosted image should be here but it was not working when we last tested it.
I like the way they look, but I need to cut a chunk of material out of both back panels to accommodate them. Will these negatively affect the sound of the enclosure? Will they be fine as long as I fit it snuggly and make sure it's air tight? Will the rigidity of the rear panel be ok with the material I have to cut out of it? I'm planning to mount them off centre between the holey brace running front to back, and the corner of the box.
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