Solid Vibration
Guys, Dudes, Lads, Blokes,
I'm breaking these woofers in with a 10 to 25 Hz sweep tone.
When in phase, these cones shake the floor!
This is considerable. Right now they're out of phase and the shaking is far less.
Having the pair thrust in opposite directions must make a difference in a cabinet, especially an ornate one with hinges and handles.
Guys, Dudes, Lads, Blokes,
I'm breaking these woofers in with a 10 to 25 Hz sweep tone.
When in phase, these cones shake the floor!
This is considerable. Right now they're out of phase and the shaking is far less.Having the pair thrust in opposite directions must make a difference in a cabinet, especially an ornate one with hinges and handles.
TS After Short Break In
All,
Here are the measured parameters after maybe 10 hours of sweep tones from 20 to 40 hz:
Driver A:
Fs 29.61 Hz
Qts 0.394
Vas 364.9 L
Driver B:
Fs 30.28 Hz
Qts 0.408
Vas 371.6 L
Is 10 hours enough? I had them sweeping through resonance and moving 10 mm. Wait, Xmax was 5 mm...
All,
Here are the measured parameters after maybe 10 hours of sweep tones from 20 to 40 hz:
Driver A:
Fs 29.61 Hz
Qts 0.394
Vas 364.9 L
Driver B:
Fs 30.28 Hz
Qts 0.408
Vas 371.6 L
Is 10 hours enough? I had them sweeping through resonance and moving 10 mm. Wait, Xmax was 5 mm...
Attachments
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Clarification: I might not have even gotten 10 hours on these. How many hours does it take to fully break-in a large woofer? I can move these twice as much, I only had them going 5 mm each way and Xmax is 11mm.
If I am not close and these measurements are still "before," please let me know.
thanks,
Paul
If I am not close and these measurements are still "before," please let me know.
thanks,
Paul
Here are two fairly good resources on break in.
Speaker Break In: Fact or Fiction? | Audioholics
Untitled Document
The former says 10s of seconds, the latter found changes in measurements up to the 80 hour point. In the latter case though the drivers were only pushed to about 1/2 xmax, which may explain why the changes kept occurring over long periods of time.
If you physically push the cone in and out once, pushing it past xmax, you can probably get most of the break in done in a matter of 1/2 a second and without even applying power to it.
The only things that are going to change are the compliance of the spider and surround which will affect fs, qts (specifically qms) and Vas. But you will probably notice that the specs shift in complementary ways so that if you sim the driver in a given box before and after break in, the simulated results will be very close. So while the parameters do shift, they shift in ways that keep the box requirements the same.
Break in doesn't affect anything electrical or any parameters that aren't affected by spider and surround compliance.
Just,
Second link is especially interesting - - the author applied 40 Hz at enough for just over 1/2 Xmax for the test intervals.
I think I should be a little more bold with this burn-in. A much narrower sweep around the Fs, up to 2 cm movement holding a ruler behind the driver to approximate it, in other words 1 cm one way, most of the Xmax.
Wife is not quite as understanding that we must have stable parameters, but what else can I do?
Second link is especially interesting - - the author applied 40 Hz at enough for just over 1/2 Xmax for the test intervals.
I think I should be a little more bold with this burn-in. A much narrower sweep around the Fs, up to 2 cm movement holding a ruler behind the driver to approximate it, in other words 1 cm one way, most of the Xmax.
Wife is not quite as understanding that we must have stable parameters, but what else can I do?
Zwiller, I agree with you. I am thinking about going the same route in my living room. I intend to build a sub that looks like this chest of drawers. It will look identical to this, except the doors won't open, they'll just be there to make it 'look' like it's a chest of drawers, not a subwoofer:
OP - a few years back I built a massive sub using dual twelves. I had to throw it away because there was a lot of flex. Basically the sub was unusable with more than about ten watts, it flexed so bad the flexing was more audible than the sub itself.
I think you may run into similar issues with your project, *even if you brace it properly.* Basically your design is going to flex the walls of the house itself. (Dual twenty ones with a lot of power will do that, you can see videos of this on Youtube.)
One possible solution might be to go with a design that has lower pressure. For instance, a horn loaded ten or twelve will have high pressure at the throat, but low pressure at the mouth. That may reduce the flexing issue.
These challenges make me miss the good ol' days when I had a concrete basement for a listening room.
I have tried something similar. Lots, and lots of screws and brace supports later there was still at least one rattle. One I couldn't pinpoint well enough to unleash one last barrage. In the end the white flag went up.
Not setting out to discourage anyone. For starters that piece of furniture looks more substantial than mine was.
Incorporating subs in a sofa is a nice idea. Or may cause similar amounts of hair loss for someone.
Foot rests are a good bet, built from scratch then upholstered. They double as a tootsie massager. And many know a foot massage is one heck of a good bargaining chip 😉
Not setting out to discourage anyone. For starters that piece of furniture looks more substantial than mine was.
Incorporating subs in a sofa is a nice idea. Or may cause similar amounts of hair loss for someone.
Foot rests are a good bet, built from scratch then upholstered. They double as a tootsie massager. And many know a foot massage is one heck of a good bargaining chip 😉
Patrick,
Spouse: Why the hell won't these drawers open?!
Patrick: Yeah, Honey, I was going to tell you about that...
dischoe,
Spouse: Aaahhhh!
dischoe: Uhh, yeah, Honey, that's just the movie trailer, the footrest didn't explode...
Spouse: Why the hell won't these drawers open?!
Patrick: Yeah, Honey, I was going to tell you about that...
dischoe,
Spouse: Aaahhhh!
dischoe: Uhh, yeah, Honey, that's just the movie trailer, the footrest didn't explode...
Not to overshare, but my wife has accepted 1 hour a day of vigorous...woofer break in. I have the sweep going a couple times a second about the Fs so from outside it sort of sounds like a dying washing machine from the 60s.
Also, the lead wire and epoxy just arrived!
Also, the lead wire and epoxy just arrived!
Really? You have to bargain for break in? I would go nuts too if you were running sweeps all day, but you don't have to, you are doing it wrong if you want to stay married.
Sweeps are a waste of time. You want the max cone motion with the minimum amount of power, so set your frequency generator to driver fs and blast it with a sine wave (or even a high crest factor signal at fs so it doesn't heat the driver up much). Set the drivers up cone to cone.
If you run them out of phase it should be whisper quiet (they will mostly acoustically cancel each other) but they will vibrate violently. If you wire them in phase it will be louder but they will force cancel each other so there will be no vibration ruckus. If noise is an issue wire them out of phase and put them on a bed or something to dampen the vibration.
Bolt them together. Just make sure that they are not touching each other, the air needs to escape (if they are in phase), so keep them about an inch apart at least, cone to cone, bolted with a bunch of nuts to keep the drivers attached to each other.
Like so - the red lines are the bolts, the green things are nuts to keep the drivers in place on the bolts and firmly attached to each other. Then choose in phase (for vibration cancellation) or out of phase (for noise cancellation) wiring, sit them on a couch or bed (making sure not to block the pole vents if the drivers have pole vents) and fire it up.
An externally hosted image should be here but it was not working when we last tested it.
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Break In
Just, man, you have excellent ideas! In electrical phase, thrusting towards and away from each other. Acoustically and mechanically cancelling.
Right now mine are out of phase and not that loud, but they’re sort of see-sawing the floor.
Just, man, you have excellent ideas! In electrical phase, thrusting towards and away from each other. Acoustically and mechanically cancelling.
Right now mine are out of phase and not that loud, but they’re sort of see-sawing the floor.
Just got the buffet which had been back-ordered. Beautiful piece, it's a shame what I'm going to do to it. 300 liters gross volume if I do a planar isobaric config.
Paul FX
Paul FX
Pardon the butt-in.... Have you considered a pair of subwoofer armchairs (or the isobaric love seat)? Functional & tickles the bits same-old-timeously.... Otherwise, leave room in the front of the hutch for the wife's teacups.
I think it's a great idea to make a sub that looks like a piece of furniture. WAF is part of the design process, or the whole project could be doomed.
That said, and knowing a little bit about furniture, I think trying to convert an actual sideboard into a sub will be tremendously difficult, if not impossible The plywood used in most furniture is the cheapest the manufacturer could find, full of voids and half glued sheets. The back side is often no thicker than 3/16". The glass will blow out your very first blast. Any framework inside usually reinforces the entire structure, so if any has to be removed, goodbye support - and trying to remove it could very well destroy the whole thing anyway, being glued and screwed (or stapled) together. The joints were never intended for the forces they will encounter, and probably every one will burst, if not at first, then soon after.
In the end, if you actually get it to work, it will be only by putting more work into it than if you had built it from scratch.
Best thing, IMO, is to build your sub, then screw some fake doors and fancy bits to the front and sides and finish it up nice. Done, and done right.
But in any case - good luck!
That said, and knowing a little bit about furniture, I think trying to convert an actual sideboard into a sub will be tremendously difficult, if not impossible The plywood used in most furniture is the cheapest the manufacturer could find, full of voids and half glued sheets. The back side is often no thicker than 3/16". The glass will blow out your very first blast. Any framework inside usually reinforces the entire structure, so if any has to be removed, goodbye support - and trying to remove it could very well destroy the whole thing anyway, being glued and screwed (or stapled) together. The joints were never intended for the forces they will encounter, and probably every one will burst, if not at first, then soon after.
In the end, if you actually get it to work, it will be only by putting more work into it than if you had built it from scratch.
Best thing, IMO, is to build your sub, then screw some fake doors and fancy bits to the front and sides and finish it up nice. Done, and done right.
But in any case - good luck!
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Exactly the point, build the armchairs / sofa from scratch around the subwoofer enclosure(s). The arm rests could house the vents; the drivers could fire between the knees.... Leave room to add cushions!
Just go for it. Add necessary quality plywood internally and brace. Lots of construction adhesive and screwed to the hilt. Replace front glass, it will break as mentioned on the first blast. Use plexiglass and replace them, just like the car audio guys do to show off their Boom'n subs and you'll be fine. Epoxy some plates down and add some LED lighting inside to show case your design if you feel like it.
I've done end tables, a coffee table and a sideboard myself and they all worked fine. Best part is, it'll look like a quality high end piece of furniture that is hard for the DIY'er to pull off without a complete shop. I did mine in an apartment living room, thus also means my wife is highly tolerant of my habits 😉
Thank GOD we do not live in an apartment anymore. The last 4 years was enough to last a lifetime. 🙂
I've done end tables, a coffee table and a sideboard myself and they all worked fine. Best part is, it'll look like a quality high end piece of furniture that is hard for the DIY'er to pull off without a complete shop. I did mine in an apartment living room, thus also means my wife is highly tolerant of my habits 😉
Thank GOD we do not live in an apartment anymore. The last 4 years was enough to last a lifetime. 🙂
Yes, it turns out, after a couple glasses of wine, that my wife was not happy about me gutting it from the back and fastening a plywood wall right behind the doors and drawers. She asked about keeping one drawer, but that would reduce the volume, and we can't have that...
you should build a tuned particle board or plywood enclosure for those drivers and then mount that inside the hutch.
the Bass will be better and you may even be able to keep a working drawer or two
the Bass will be better and you may even be able to keep a working drawer or two
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Typical American Princess mentality... It's our Castle, but her Palace.
Bet you only have a garage or workshop as your "space" like most men I know. Sad but true.
Tell her: Sure thing dear, but they'll probably shatter on the first BOOM!
Why does alcohol bring out the truth? I know the answer. TY 😉
Once I used slang word JAP, when referencing typical US prejudice during and after WWII. It was said in context to the discussion and not ment that I or anyone else participating was. One guy on our forum got his panties all in a bunch and started defending his wife... He thought I was derogatorily referencing Jewish American Princess 🙄
Bet you only have a garage or workshop as your "space" like most men I know. Sad but true.
Tell her: Sure thing dear, but they'll probably shatter on the first BOOM!
Why does alcohol bring out the truth? I know the answer. TY 😉
Once I used slang word JAP, when referencing typical US prejudice during and after WWII. It was said in context to the discussion and not ment that I or anyone else participating was. One guy on our forum got his panties all in a bunch and started defending his wife... He thought I was derogatorily referencing Jewish American Princess 🙄
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