The only resonances would be in the audio frequency range. An aluminum brace in the length you would use will have a resonance in the audio band. If you care to try, just tap a piece on one end with a hammer. Do be sure to wear earplugs!
As to gluing lignum vitae, you normally use an alcohol soak to remove the oil at the glue joint and then it will glue up nicely. Best with a urethane glue.
Now I can see you having a bit of lignum vitae, but not enough to waste on cross braces. Runs about $8 a pound these days. I don’t use lignum vitae for clock parts. It gets used around here for inlays and mallet heads.
The only excitation will be from a 12 inch woofer. If I keep the structure stiff enough to exceed 4kHz resonance, no worry. The eminence delta 12 pro peaks (in front) at 3kHz, drops off fast. I suspect nuttin will happen to the supports.
I can also attach some damping to the support if I'm worried.
My concern with gluing LV is long term. I know the surface can be cleaned with alcohol, but I worry about long term.
I forgot what I paid for it, I believe it is from Brazil, and stuff from Africa is banned. I bought it to use as pallets in escapements. But man, it is some really dense stuff.
John
I can also attach some damping to the support if I'm worried.
My concern with gluing LV is long term. I know the surface can be cleaned with alcohol, but I worry about long term.
I forgot what I paid for it, I believe it is from Brazil, and stuff from Africa is banned. I bought it to use as pallets in escapements. But man, it is some really dense stuff.
John
You could think of mahogany, teak, ironwood, Douglas fir, or similar hard wood species.
And think of a turnbuckle, clamp the ends to the walls, tighten as needed.
And think of a turnbuckle, clamp the ends to the walls, tighten as needed.
I use lignum vitae for the drawer handle on my nightstands. The rest is padauck. (Except drawer bits are hard maple.). Only been using them 20+ years. Did build at least half a dozen of them so far. Decent wedding or house warming gifts.
You really need to tap an aluminum rod to understand how much it rings. Although the gummiest alloys don’t ring as much, they really aren’t suited for braces.
The thing to keep in mind is that the box walls move from both positive and the negative changes of the internal pressure in addition to the vibration from the actually really small diaphragm moving mass. So a well glued wood brace would be my choice. You can even use some fiberglass cloth to wrap the ends and get an attachment that just might be strong enough to survive Re-entry!
In fact I suspect if you use either hard maple or white oak for the well glued brace the finished boxes could survive a fall of one hundred feet! Of course to do this drop them from a height of one hundred and one feet! After all it is the landing that will do them in!!!
You really need to tap an aluminum rod to understand how much it rings. Although the gummiest alloys don’t ring as much, they really aren’t suited for braces.
The thing to keep in mind is that the box walls move from both positive and the negative changes of the internal pressure in addition to the vibration from the actually really small diaphragm moving mass. So a well glued wood brace would be my choice. You can even use some fiberglass cloth to wrap the ends and get an attachment that just might be strong enough to survive Re-entry!
In fact I suspect if you use either hard maple or white oak for the well glued brace the finished boxes could survive a fall of one hundred feet! Of course to do this drop them from a height of one hundred and one feet! After all it is the landing that will do them in!!!
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I have LOUD wind-chimes made of plain Aluminum tubing.
When Pete Traynor was running a rental business, he would push his PA and guitar-amp gear out of an upper floor of the factory. His early stuff was built to survive that. (Not unblemished, but so the show would go on.) Of course Pete and all of us were younger then....
Funny Nigel. I often look at DJs and think they have it so easy. Not much gear and all of it light weight. Nothing like concert gear. But DJs don’t have a crew of two or three dozen shifting all that gear, do they?
Oh, come on… you’re supposed to DJ with concert gear. Back in the 80’s that was the rule, not the exception. As much as your crew of 2 could cram into the available trucks/trailer, and could move without ending up in the hospital. Nowadays it’s cute little plastic boxes, and wondering why you can’t get the same sound out of it without catching something on fire.
Started making the amp box, a 2 RU by 18 inch deep one.
First, a 1/2 inch ply box with sides, top and bottom. 18 inches deep, and internal dimension 19 1/8th by 3 5/8th. Not sure how thick the carbon fiber cloth will be, so left room in case I fold it into the box.
Next, a 5/16 MDF router template. I locate it on the box with three dogs, two in front and one on a side in the middle.
Here is the box with routed top and bottom.
Here is a test fit of the amp. Note that I left the sides full, no cutout. I will be adding supports to the back sides as the amp has brackets for side mount there, will add strength. Note that the amp is not supported along the sides, as the hole is larger than the amp. I will probably glue a 1/2 inch ply by 1 inch wide support on the top and bottom so they touch the amp from front to back.
This box is just the half inch inner, I will be adding a layer of 1/4 inch all around then the carbon.
Box started at over 7 lbs, so far it's 2.44 lbs. I think it will be 3.5 lbs in the end prior to clothcoat.
Oh, btw...checked out the 3/8th rounding router bit with my construction, once the 1/4 layers are added, the router bit cannot hit any of the nails. That made this part of the project so much easier, as I love using the nails to lock the glue-up, clamps are a pita.
John
First, a 1/2 inch ply box with sides, top and bottom. 18 inches deep, and internal dimension 19 1/8th by 3 5/8th. Not sure how thick the carbon fiber cloth will be, so left room in case I fold it into the box.
Next, a 5/16 MDF router template. I locate it on the box with three dogs, two in front and one on a side in the middle.
Here is the box with routed top and bottom.
Here is a test fit of the amp. Note that I left the sides full, no cutout. I will be adding supports to the back sides as the amp has brackets for side mount there, will add strength. Note that the amp is not supported along the sides, as the hole is larger than the amp. I will probably glue a 1/2 inch ply by 1 inch wide support on the top and bottom so they touch the amp from front to back.
This box is just the half inch inner, I will be adding a layer of 1/4 inch all around then the carbon.
Box started at over 7 lbs, so far it's 2.44 lbs. I think it will be 3.5 lbs in the end prior to clothcoat.
Oh, btw...checked out the 3/8th rounding router bit with my construction, once the 1/4 layers are added, the router bit cannot hit any of the nails. That made this part of the project so much easier, as I love using the nails to lock the glue-up, clamps are a pita.
John
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I trust you will shortly see the problem!
But you only need to add to the top and bottom, not the sides.
Are you routing for the handles?
Where does the power cord go? Is there a rear connector panel?
But you only need to add to the top and bottom, not the sides.
Are you routing for the handles?
Where does the power cord go? Is there a rear connector panel?
What problem? I am duplicating a 3RU box I built about 15 years ago.
Edit: AH, I see what you mean. My mill y axis handwheel is too close to the bench. Unfortunately, it is a ceiling issue. As it is, I had to place the mill on the bench between ceiling joists so I could raise it full height. Even then, the handle hits the AC flexible ductwork. Since I'm short, the low ceiling doesn't bother me.
I'm adding the sides as I will roundover all edges and didn't want to worry about nails.
Handles are those rubber coated ones that lie flat against the side, but have slotted steel inserts to allow the handle to pull away from the box allowing the hand.
I will probably add a connector panel to allow 4 1/4 speaker outs, 4 neutrik speakons, just to give flexibility in setup.
Also, another panel for inputs.
I plan on just using the amp IEC for power directly. With maybe five gigs a year, I ain't wearing the connector out. Typically I will twist the power cord and two balanced runs together, cover with nylon braid, and use it as the umbilical from the amp to the mixer. Mixer will have a power distribution setup.
Setup is.... put mixer on stand, connect umbilical from mixer to amp...connect power to mixer. Done.
I don't do huge setups like you. Simple is better for me. There is only so much real estate on my left palm to write down what connects to what, so the less connections I have to do, the better. I can't write on my right palm to double my remembrances.
John
Edit: AH, I see what you mean. My mill y axis handwheel is too close to the bench. Unfortunately, it is a ceiling issue. As it is, I had to place the mill on the bench between ceiling joists so I could raise it full height. Even then, the handle hits the AC flexible ductwork. Since I'm short, the low ceiling doesn't bother me.
I'm adding the sides as I will roundover all edges and didn't want to worry about nails.
Handles are those rubber coated ones that lie flat against the side, but have slotted steel inserts to allow the handle to pull away from the box allowing the hand.
I will probably add a connector panel to allow 4 1/4 speaker outs, 4 neutrik speakons, just to give flexibility in setup.
Also, another panel for inputs.
I plan on just using the amp IEC for power directly. With maybe five gigs a year, I ain't wearing the connector out. Typically I will twist the power cord and two balanced runs together, cover with nylon braid, and use it as the umbilical from the amp to the mixer. Mixer will have a power distribution setup.
Setup is.... put mixer on stand, connect umbilical from mixer to amp...connect power to mixer. Done.
I don't do huge setups like you. Simple is better for me. There is only so much real estate on my left palm to write down what connects to what, so the less connections I have to do, the better. I can't write on my right palm to double my remembrances.
John
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I showed that picture to my wife eons ago... when we drawing the plans for the house rebuild... I needed a 24 foot high living room, I said!
Needless to say, I got to live with an 8 foot ceiling.
I was planning to work with my son and his bass guitar to wire it so each string would have its own cab.... unfortunately he decided to take a job 1200 miles up the freeway before we got the project underway...
I totally agree. "Heavy" as a descriptor somehow falls short.
However, if I buy something lighter, I could not part with a working amplifier. My basement is only so big... But I do worry about the electrolytics, I'm hoping the shelf life is long.
I was shocked to find the price of the 1450 is now in the 900 dollar range. Holy mackeral.
This thread, and this build, is an old man's way to compensate for the rising tide of gravity, using material on hand. I continue to post on this thread only to show what I am doing, materials and methods. Some people will find this of use. (well, at least that's my story and I'm sticking with it..)
PS. "dinosaur"... You sound like the kid I told them to hire to replace me. World SOTA machine (25 years so far), 100 MHz pentium, 40 meg hard drive, ISA bus to motion control cards, no USB interface, only CD, windows 95...Where's the problem? It works, so don't fix it.
Course, the hardware is 30 years old. And the software isn't taught in school anymore. What is this C sharp, and how do clouds help???
I'm still waiting for Ed to tell me what I'm missing. My "problem" so to speak.
While I am very good at what I do (whatever that is), I still worry that I am doing something stupid. (THAT is of course, within my DNA so totally unavoidable.).
John
A hi level guy at work is gonna buy some diodes, 4K dollars per. Your neck of the woods.
Since I'm the diode guy, I'll be in your vicinity in the near future.
You would be very wise to..... hell, I don't what that sentence could possibly lead to, but it was sounding cool for a while....
If I am in your neighborhood, it would be so cool to visit your company, I hope it can happen.
John
There's nothing wrong with old tech. Im still a fan with my thousands of CDs and records I absolutely couldn't do without. I'm in my.50s and BTW love my analog gear as much as the newer "actually improved" digital gear. Thats really the point I'm trying to make, denying yourself the benefits of modern gear where its useful ie. computers and hardware which enable recording at higher bit rates with lower latency and many tracks running (reliably) at the same time. If your win95 machine is still going and works for you, that's absolutely fine. I just wouldn't want to wait 20 min to render a 5 min wav file for EQ processing vs a few secs.
Theres nothing wrong with the rmx1450 amp, other than its heavy and expensive (linear PS with big transformer) compared to the (also made in China) GX7 with way more power and a lighter, higher current switching supply. They both sound the same to me, except for way more headroom on the GX7. They're just as reliable from my experience as the RMX series, aside from being able to throw an RMX2450 off the roof of the QSC office building and having it still work. I tried posting the video, but it kept saying it was unavailable once the link was posted on here.
Just let me know when, so I can be sure all the dogs get their teeth sharpened!
They will be looking forward to it.