Silk I think....
a hard mono filiment fiber is just going to be to hard and stiff to gently fold its way about the iside of the cabinet. Soft supple Silk is what you want, I don't think that the colour will matter much. But the nut??? Imperial or metric is this a Japanese driver? Go metric then. Good luck Cal. Then again a well trained mouse might just be the ticket.
a hard mono filiment fiber is just going to be to hard and stiff to gently fold its way about the iside of the cabinet. Soft supple Silk is what you want, I don't think that the colour will matter much. But the nut??? Imperial or metric is this a Japanese driver? Go metric then. Good luck Cal. Then again a well trained mouse might just be the ticket.
You guys all have good ideas, but believe it or not, the best idea I could come up with at the time was a coat hanger. The alternative to that was to borrow the kid next door and see if his hand was small enough to fit through the bend. Fortuitously I didn't need to decide between these two, as I was finally able to just thread the wire itself around the bends and grab it with tweezers when I saw it through my pilot hole.
just a guy said:
Retrofit with threaded insert fittings ( not T-nuts) and machine screws. Black oxide finished socket cap screws look particularly nice on the Sigma drivers.
Normally you'd hammer them in place before attaching the front baffle, but they can also be tightened with the aid of a flat washer on the front side.
Understood. Thanks for the tip about not using t nuts, as that would have been my first choice if/when the threads are stripped on the wood.
What about the cc size though? How did 1.8 liters work for you? Those plans were published very early in the development of these speakers, have there been any insights since then? This is my first fullrange project, so I could literally spend days finding the happy balance since I have no point of reference as to what to expect.
What about the cc size though? How did 1.8 liters work for you? Those plans were published very early in the development of these speakers, have there been any insights since then? This is my first fullrange project, so I could literally spend days finding the happy balance since I have no point of reference as to what to expect.
1.8 litres is just about right for the 108...
As to inserts of t-nuts, i prefer to pull them in from the front using a washer and sacrificial bolt(s). This ensures that they are perpendicular.
T-nuts tend to come loose, so if you use them it is important to be able to get at the back of the install if they screw up. For instance in the woofer shown (to preserve my collection of recycled inserts) i used t-nuts on the bolts holding the feet, but inserts to hold the driver. If they ever screw up, driver comes out and i can get at them.
Note: this frugal-phile(tm) woofer was made using woofers (ApexJr Super8) i exchanged for some design work, recycled wood, posts, and bolts, inserts, & t-nuts, the (hide all evils) paint cost $4 & the feet cost something like $12 (& there is an optional set of brass spikes i might use instead of the rubber feet).
dave
As to inserts of t-nuts, i prefer to pull them in from the front using a washer and sacrificial bolt(s). This ensures that they are perpendicular.
T-nuts tend to come loose, so if you use them it is important to be able to get at the back of the install if they screw up. For instance in the woofer shown (to preserve my collection of recycled inserts) i used t-nuts on the bolts holding the feet, but inserts to hold the driver. If they ever screw up, driver comes out and i can get at them.
Note: this frugal-phile(tm) woofer was made using woofers (ApexJr Super8) i exchanged for some design work, recycled wood, posts, and bolts, inserts, & t-nuts, the (hide all evils) paint cost $4 & the feet cost something like $12 (& there is an optional set of brass spikes i might use instead of the rubber feet).
dave
Attachments
Ahhh, much better now.
Not perfect yet, but with 4 bars of ivory soap in the chamber, and the driver area subtracted, I'm in the ballpark at least. And it makes the house smell nice.
It sounds very nice now, dripping with detail, with a killer midbass snap that could take your head off. Maybe a bit too much midbass, but it's all cool for now. Low bass is mia, but that's ok and expected. It gets plenty loud in it's comfort zone range.
Not perfect yet, but with 4 bars of ivory soap in the chamber, and the driver area subtracted, I'm in the ballpark at least. And it makes the house smell nice.
It sounds very nice now, dripping with detail, with a killer midbass snap that could take your head off. Maybe a bit too much midbass, but it's all cool for now. Low bass is mia, but that's ok and expected. It gets plenty loud in it's comfort zone range.
I bought the drivers used, no idea how much time was on them at that point, but I'll assume zero. I used them for tv duty for a couple of months (at least) but they were never pushed above comfortable conversation levels. Now that they are in horns I'm having fun pushing the snot out of them.
Soap was the first thing I could find that would fit through the hole and "stack" nicely. Once I figure out how much volume needs to be displaced, I will replace the soap with wood pieces. No green tea soap onhand, but I'll keep it in mind as an upgrade/tweak.
BTW, there's only one box done so far, I still have to get out to the shop and finish the other one.
Soap was the first thing I could find that would fit through the hole and "stack" nicely. Once I figure out how much volume needs to be displaced, I will replace the soap with wood pieces. No green tea soap onhand, but I'll keep it in mind as an upgrade/tweak.
BTW, there's only one box done so far, I still have to get out to the shop and finish the other one.
chrisb said:
While the selection of threaded wood inserts readily available today weren't AFAIK when I was actively building (the ones I remember were relatively expensive and required a $ special kit $ to make the hole), I never had any of the problems with T-nuts others claim except for having to cut/grind off part of the flange when the holes were close to the edge of the cutout. Indeed, I've been uninstalling/reinstalling multiple 15s on an annual basis since '69 with nary a problem as once properly embedded with a dab of construction adhesive it takes a lot to pry them out.
GM
Mounting threads
OK, so this is off-topic - maybe it deserves a thread of its own
- but I'd like to hear the downside of what I do, which is this:
1. Drill tap-size holes directly in the (Baltic birch) front panel. I use a 5/32" drill for 10-32 bolts, since number drills are still on the wish list.
2. Thread the holes.
3. Soak in as much unthickened epoxy as the wood will take.
4. Rethread the holes.
This may not be sufficiently durable for those who remove and replace drivers hundreds of times, but the curvey Harveys have gone through this cycle a couple of dozen times now with no problem.
Cheap, easy, and effective - so why use inserts or t-nuts?
[edit] For those who do use t-nuts, the recommendation is use the 3-prong ones for plywood, 4-prong in solid wood, and 6-prong for "softer materials and composites" (per Lee Valley t-nuts page). Perhaps doing otherwise may have led to the issues some posters have reported? [/edit]
Regards.
AengusLee Valley t-nuts page
OK, so this is off-topic - maybe it deserves a thread of its own
- but I'd like to hear the downside of what I do, which is this: 1. Drill tap-size holes directly in the (Baltic birch) front panel. I use a 5/32" drill for 10-32 bolts, since number drills are still on the wish list.
2. Thread the holes.
3. Soak in as much unthickened epoxy as the wood will take.
4. Rethread the holes.
This may not be sufficiently durable for those who remove and replace drivers hundreds of times, but the curvey Harveys have gone through this cycle a couple of dozen times now with no problem.
Cheap, easy, and effective - so why use inserts or t-nuts?
[edit] For those who do use t-nuts, the recommendation is use the 3-prong ones for plywood, 4-prong in solid wood, and 6-prong for "softer materials and composites" (per Lee Valley t-nuts page). Perhaps doing otherwise may have led to the issues some posters have reported? [/edit]
Regards.
AengusLee Valley t-nuts page
Been there, done that and should work fine indefinitely for light weights, but heavy, forget it as the base material would deform if other than top mounted. The bottom line for me was speed and this is too time consuming when I could pull down (and later, press in) an adhesive coated T-nut like right now, though I did/do use/recommend it on some types of repair.
WRT using different pronged T-nuts, this makes sense if no construction adhesive (or epoxy if you prefer) is used. Note that I have never used nor would ever recommend any of the various particleboards to mount drivers, so anyone who's had problems with T-nuts in this app just 'reaped what they sowed' IMO, though as always YMMV.
GM
WRT using different pronged T-nuts, this makes sense if no construction adhesive (or epoxy if you prefer) is used. Note that I have never used nor would ever recommend any of the various particleboards to mount drivers, so anyone who's had problems with T-nuts in this app just 'reaped what they sowed' IMO, though as always YMMV.
GM
Good point - I've used it only with small Fostexes, and hadn't considered the weight issue.
We won't go into the speed issue, given the time it takes me to turn out a pair of speakers.
[edit] On consideration, you could do what the boat guys do to mount hardware: drill an oversize hole, coat the bolt with wax or similar, brace it in place while you fill the oversize hole with epoxy. This gives you a larger bearing surface on the substrate (in this case the front panel) and should prevent deformation. It handles high strain loads (holding sheet cleats, for example) so should hold a speaker. Still time-consuming, though.
Also, my previous post perhaps should have mentioned that the epoxy must be allowed to harden before the hole is re-threaded. [/edit]
Regards.
Aengus
Aengus said:
Good point - I've used it only with small Fostexes, and hadn't considered the weight issue.
We won't go into the speed issue, given the time it takes me to turn out a pair of speakers.
[edit] On consideration, you could do what the boat guys do to mount hardware: drill an oversize hole, coat the bolt with wax or similar, brace it in place while you fill the oversize hole with epoxy. This gives you a larger bearing surface on the substrate (in this case the front panel) and should prevent deformation. It handles high strain loads (holding sheet cleats, for example) so should hold a speaker. Still time-consuming, though.
Also, my previous post perhaps should have mentioned that the epoxy must be allowed to harden before the hole is re-threaded. [/edit]
Regards.
Aengus
Aengus,
Ed Heath on the old Bass List used the "Epoxy Insert" method years ago and claimed it worked very well if enough epoxy and surface area was used. For small drivers, Ed used to install the drivers with screws, then disassemble and apply "Super Glue" to the threads in the MDF. After it soaked in and hardened the driver was replaced. The super glue, much like thin epoxy, soaked into the threads and surrounding area and created a form of case handening.
Works well, I've done it myself :^)
BTW: Hows the canoe coming along?
Best Regards,
TerryO
After a comedy of errors the second box is mostly finished, it will be listenable tomorrow.
In the meantime I'm having a nasty, awful time trying to tune the first one. Today was the first time I stopped listening exclusively to the bass spl potential and started listening to voices. Vocals served to prove that I have a big midbass problem, even female vocals resonate throughout the whole room. I ended up taking everything out of the cc again and that helped but not enough. I had to pull the speaker about 3 feet out of the corner and that helped too but not enough.
So I fired up my media player eq and... I noticed that I had forgotten to turn off the 6db BSC I was using from 125 hz and down on the last speakers. So I turned that off and things improved immensely, but now even with a flat signal, no cc fill and 3 feet out from the corner I still have a touch of a midbass problem.
Taking 250 hz down 3db and boosting 125 hz 3db seems like a happy compromise for the moment, but I'd rather solve this mechanically.
This midbass problem might have more to do with the room than the speakers so I'll have to move this setup around the house a bit.
In the meantime I'm having a nasty, awful time trying to tune the first one. Today was the first time I stopped listening exclusively to the bass spl potential and started listening to voices. Vocals served to prove that I have a big midbass problem, even female vocals resonate throughout the whole room. I ended up taking everything out of the cc again and that helped but not enough. I had to pull the speaker about 3 feet out of the corner and that helped too but not enough.
So I fired up my media player eq and... I noticed that I had forgotten to turn off the 6db BSC I was using from 125 hz and down on the last speakers. So I turned that off and things improved immensely, but now even with a flat signal, no cc fill and 3 feet out from the corner I still have a touch of a midbass problem.
Taking 250 hz down 3db and boosting 125 hz 3db seems like a happy compromise for the moment, but I'd rather solve this mechanically.
This midbass problem might have more to do with the room than the speakers so I'll have to move this setup around the house a bit.
The boxes are made from 5 layer arauco ply. It sells as 12 mil but measures 11 mil. This wood is used on all outside panels as well and the plans were adjusted to take the thickness of the outside panels into consideration (slightly less tall and deep than if I used thicker wood for the outsides).
No chamfer on the baffle, but that was done because the wood is so thin already that if I chamfered it the driver mounting screws would have almost nothing to grab onto. If this proves to be a big concern I can retrofit a chamfer with a file and a few minutes (hours?) of work. For that matter, I could fit another thickness of wood to the whole front baffle and make a larger chamfer.
The drivers are very well sealed with a thick foam weatherstrip homemade gasket.
Absolutely no idea how many hours on the drivers. I got them used and have used them since as tv speakers in small ported boxes, but never beyond conversational levels.
The cab (still only one done now) has been tried in a couple of different corners. The 2 corners I've tried are both in a recessed alcove in a very large room that is open to the entire house. The alcove measures about 3 feet deep x 9 feet wide (by looks). This alcove is nested in a corner of the large room. So it's in an alcove in a corner. (Supercorner?) It has been placed everywhere from 5 inches from the corner to about 3 feet away from the corner (slightly past the "mouth" of the alcove). Pushing the speaker back into the corner makes the midbass problem more pronounced (subjectively - no measurements yet). Pulling it out past the alcove mouth cleans up the midbass a bit but it's still too strong. Maybe the size and shape of the alcove are a problem, still have to test in different rooms.
No suprabaffles, since these are a gift for a girl, so waf is of ultimate importance. It's my sister's wedding present. Some girls might appreciate the looks of level 3, but I don't think it would go over well. I can fashion some slip on suprabaffles for testing, but I actually think they would make the problem worse. If I have too much at 250 hz, a suprabaffle would certainly bring that 250 hz up in volume a bit. To my untrained ears (and brain) I can't see a suprabaffle helping, but I'm willing to try.
Also, the sealed wasted space chamber is unfilled. This might be a mistake, not sure how much that big unfilled chamber can contribute. I was going to leave it open with a "fill hole" so they could fill it with sand when they get it home, but I can almost guarantee they won't. Weight is a major concern here too, since they have to take these back in a suitcase and the limit is 60 lbs. Currently, without drivers, it weighs 13.5 lbs (each), so filling with sand now may (or may not) take me close to the luggage weight limit.
No chamfer on the baffle, but that was done because the wood is so thin already that if I chamfered it the driver mounting screws would have almost nothing to grab onto. If this proves to be a big concern I can retrofit a chamfer with a file and a few minutes (hours?) of work. For that matter, I could fit another thickness of wood to the whole front baffle and make a larger chamfer.
The drivers are very well sealed with a thick foam weatherstrip homemade gasket.
Absolutely no idea how many hours on the drivers. I got them used and have used them since as tv speakers in small ported boxes, but never beyond conversational levels.
The cab (still only one done now) has been tried in a couple of different corners. The 2 corners I've tried are both in a recessed alcove in a very large room that is open to the entire house. The alcove measures about 3 feet deep x 9 feet wide (by looks). This alcove is nested in a corner of the large room. So it's in an alcove in a corner. (Supercorner?) It has been placed everywhere from 5 inches from the corner to about 3 feet away from the corner (slightly past the "mouth" of the alcove). Pushing the speaker back into the corner makes the midbass problem more pronounced (subjectively - no measurements yet). Pulling it out past the alcove mouth cleans up the midbass a bit but it's still too strong. Maybe the size and shape of the alcove are a problem, still have to test in different rooms.
No suprabaffles, since these are a gift for a girl, so waf is of ultimate importance. It's my sister's wedding present. Some girls might appreciate the looks of level 3, but I don't think it would go over well. I can fashion some slip on suprabaffles for testing, but I actually think they would make the problem worse. If I have too much at 250 hz, a suprabaffle would certainly bring that 250 hz up in volume a bit. To my untrained ears (and brain) I can't see a suprabaffle helping, but I'm willing to try.
Also, the sealed wasted space chamber is unfilled. This might be a mistake, not sure how much that big unfilled chamber can contribute. I was going to leave it open with a "fill hole" so they could fill it with sand when they get it home, but I can almost guarantee they won't. Weight is a major concern here too, since they have to take these back in a suitcase and the limit is 60 lbs. Currently, without drivers, it weighs 13.5 lbs (each), so filling with sand now may (or may not) take me close to the luggage weight limit.
BTW, looking at the (half space?) measurements on the frugal-horn website, it probably should come as no surprise that I have a problem with midbass. Looks like a 10db or so spike right at 250, and also one at about 150 or so. I'm not sure even the most rigid corner could even those out. If it was a tl, I'd say it needed lots of stuffing. But thousands of people happily live with b horns and variants, so I'm sure there is a strategy that will work.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.