The Boominator - another stab at the ultimate party machine

Yes, a Q of about 1.1 works very well outside. And the peak comes automatically when that Q is used for the tuning.

You can expect another design to measure the same as dBoominatør even with the same speakers.

The speaker placement on the ground and the bipolar construction is crucial to have it measure and sound correct.

If you use it inside however you must lift it about 1m of the ground and at least 50cm from the nearest wall or it'll have too much bass. Placed like that it sounds excellent though.

The system is intended to be used outside (at roskilde festival ofc).
And I am only going to use 2 drivers, and 2 tweeters.. I should perhaps have written that before!
But the design idea for the system, is to make a 60x60x60cm box (dont worry, there is a plan with this giant box), and have the drivers and tweeters point in the same direction on one side of the box. Inside the "giant" box, I will make seperate champers for the drivers in order for the volume to fit the proper Qbox.

But you said that the Q of 1.1 is for boominator lookalikes that stand on the ground and have the bipolar construction. Since im not going to have that construction, but have the drivers mounted on one side, pointing in the same direction, about 40-50cm over the ground, how should I calculate the proper volume and Q then?
 
But you said that the Q of 1.1 is for boominator lookalikes that stand on the ground and have the bipolar construction. Since im not going to have that construction, but have the drivers mounted on one side, pointing in the same direction, about 40-50cm over the ground, how should I calculate the proper volume and Q then?

Then a Q of between 0.7 and 1 is the right thing. Hard to say which in the particular case. The sound will however appear "light" or "lacking body" unless you use a bafflestep filter.

Google an online cabinet calculator and how to make a bafflestep filter. I'm sorry but there are no short-cuts. It will be trial and error several times before you get a design right.
 
Then a Q of between 0.7 and 1 is the right thing. Hard to say which in the particular case. The sound will however appear "light" or "lacking body" unless you use a bafflestep filter.

Google an online cabinet calculator and how to make a bafflestep filter. I'm sorry but there are no short-cuts. It will be trial and error several times before you get a design right.

Okay, after thinking the design through, and having your comments on the system in mind, I am thinking that maybe I could go with a boominator-kind-of design, by having the drivers placed at the ground level. Because where the drivers are placed in my "giant" cube, doesnt really matter that much, it was just my first initial idea. But if it causes too much trouble and extra work, its really not worth it. :)

But having only 2 P.Audio HP10W drivers and 2 tweeters in my entire design, facing the same way, and not using the bipolar magnet to magnet design, will the Qbox still remain the same as yours? 1.1 at a ~80Hz tuning freq?

If it is, im ready to build, and have no more further questions... (at the moment ;) )
 
Good to hear that they in fact are higher than the pdf spec. The pdf actually says131.2mm. Maybe someone with a fresh HP-10W can measure the "up to date" height?

Another thing i wonder about is what kind of glue i´ll use between the magnets, should it be elastic afterwards or totally stiff? i have a tube of 2-component Chemical metal but don´t know whats best for this situation. Can your name any suiting glue? Are the magnets really intact face to face or is there like a 1mm gap of glue between?

About the magnets glued together and surrounded with the centerbrace, what happens with the heat from the magnets? Is there any chance of overheating the magnets and voicecoil in this configuration?

There is a chance i have missed this in earlier posts but what about the solarpanels and overcharging, what is a good goal for max feeding of mA and what impact has the voltage on charging the battery, should i go for a 7V or a 12V or is current the only important parameter? Should i also use some kind of charging electronic that prevents overcharging or is a voltmeter and a manual switch sufficient?

Build Status as for today:
-Piezos buyed (MGR CH-5 because they where on sale on ljudia)
-CADmodel beeing tweaked for right volume
-AMP6-B ordered
-Biggest concerns are finding right glue and sufficient solarpanel that doesn´t cost a fortune.
maybe anyone of these? or what to look for? this is a new subject to me.:

Main
 
Then a Q of between 0.7 and 1 is the right thing. Hard to say which in the particular case. The sound will however appear "light" or "lacking body" unless you use a bafflestep filter.

Google an online cabinet calculator and how to make a bafflestep filter. I'm sorry but there are no short-cuts. It will be trial and error several times before you get a design right.

Is the new Q you mention a result of using only 2 drivers pointing the same way, or a result of placing the speakers 50-60cm above ground?

I ask because we want to build a wagon for the Boominator that lifts it to about 60-80cm above ground. Should we keep the dimensions or calculate with a new Q?
 
Is the new Q you mention a result of using only 2 drivers pointing the same way, or a result of placing the speakers 50-60cm above ground?

I ask because we want to build a wagon for the Boominator that lifts it to about 60-80cm above ground. Should we keep the dimensions or calculate with a new Q?

The former. A bipolar design is vastly different than a normal design, for better and worse. Lifting it off the ground will just result in less overall bass and midbass. You won't notice the difference before you try both right after another.
 
Good to hear that they in fact are higher than the pdf spec. The pdf actually says131.2mm. Maybe someone with a fresh HP-10W can measure the "up to date" height?

Another thing i wonder about is what kind of glue i´ll use between the magnets, should it be elastic afterwards or totally stiff? i have a tube of 2-component Chemical metal but don´t know whats best for this situation. Can your name any suiting glue? Are the magnets really intact face to face or is there like a 1mm gap of glue between?

About the magnets glued together and surrounded with the centerbrace, what happens with the heat from the magnets? Is there any chance of overheating the magnets and voicecoil in this configuration?

There is a chance i have missed this in earlier posts but what about the solarpanels and overcharging, what is a good goal for max feeding of mA and what impact has the voltage on charging the battery, should i go for a 7V or a 12V or is current the only important parameter? Should i also use some kind of charging electronic that prevents overcharging or is a voltmeter and a manual switch sufficient?

Build Status as for today:
-Piezos buyed (MGR CH-5 because they where on sale on ljudia)
-CADmodel beeing tweaked for right volume
-AMP6-B ordered
-Biggest concerns are finding right glue and sufficient solarpanel that doesn´t cost a fortune.
maybe anyone of these? or what to look for? this is a new subject to me.:

Main

If you strip the 15W panel in that link from the casing it matches the top of dBoominateur 100%, and with 12W output max at our latitude it's perfect with the recommend battery size as it will just trickle charge them. You won't need a charge regulator unless you plan to just letting it sit in the sun and never play on them at all.

I use epoxy glue for the wood parts. DO NOT use this yourself. Use normal gorilla glue.

I use superglue for metal to metal joints (between the magnets for example but only as thin a layer as you possibly smear on.

I use sealant rubber for the rest and for sealing. Remember don't ever use vinegar based acrylic sealer as the fumes will eat the speaker cones slowly.

No, there's absolutely no chance of overheating the voice coil unless you decide to connect the speakers directly to a car battery in which case they'll pop in nanoseconds.
 
Okay, after thinking the design through, and having your comments on the system in mind, I am thinking that maybe I could go with a boominator-kind-of design, by having the drivers placed at the ground level. Because where the drivers are placed in my "giant" cube, doesnt really matter that much, it was just my first initial idea. But if it causes too much trouble and extra work, its really not worth it. :)

But having only 2 P.Audio HP10W drivers and 2 tweeters in my entire design, facing the same way, and not using the bipolar magnet to magnet design, will the Qbox still remain the same as yours? 1.1 at a ~80Hz tuning freq?

No, the tuning needs to be completely different. You'll need to recalculate it from the ground up.
 
Almost finished with the planing of everything now but i have a concern about the piezos i will use, here is the specs:
300w,95db, 2000-20000Hz
and here is a link:
MGR CH-5 A - Piezodiskant - REA | Skåne | Blocket

My concern is if they will be loud enough to match the woofers? One thaught i have is to mount them close to eachother on the same side to double the output in only one direction... whould this be totaly dumb since i will have the woofers in bi-polar mode?

The other big question is what kind of filter i should use with these piezos. I have read this thread and some others and only get confused when it comes to filtercalculations and setups. As i understand you get a HP filter when using metalfilm resistors and a HF-cut when using wirewound resistors in series to a piezo, is this correct? All i want with the piezos is to match them well where the woofers take off and maybe cut the top if they are anoying. Any help here would be appreciated! I would love a post like: "buy these and wire in series with..." as i don´t know the basics of calculating my own filter and since you guys and specially Saturnus probably know the Woofers curves really well by now.

I happened to see something about adding/replacing a 22,000 uF cap in the amp6, what is that about?

Is there anything easy you can do to dampen the lowest frequencies, lets say under 60Hz? Just to avoid reaching xmax and spare some valuable power.
 
I happened to see something about adding/replacing a 22,000 uF cap in the amp6, what is that about?

Is there anything easy you can do to dampen the lowest frequencies, lets say under 60Hz? Just to avoid reaching xmax and spare some valuable power.

The 22.000 uF cap is probably a reservoir cap, handing out current when there is a strong current pull from the amp. This is a simple addition. (I'm guessing that that's what this size of cap would be. Maybe there are some implementation specifics in this case that I don't know ... But AFAIK you'd want a ~25V 22000uF electrolytic cap, either on the board if one fits or located on the power feed cables, on an aux. board.)

Re. the low-frequency stuff: You can change the input cap to a smaller value. This is a really easy way to do EXACTLY what you want :) There's a formula in the tripath chip datasheet that tells you what value you want. Somewhere about 0.1uF to 0.5uF should be pretty effective here.
 
Found it! It saw on the assembly instruction for the AMP6-B acctually=)

I drove to Ljudia yesterday and bought the 4x HP-10W by the way....when i got home and tested them two of them had defects!! It almost seems like the cone is made of dual layers of paper and that there is no glue in between, resulting in a rattling/broken sound when playing bass. Ever thumping on the cone with your fingers generat this rattling sound. I´m replacing them in the end of the week.

Another thing i noticed is that the total height of HP-10W is 132,5mm resulting in a total "bi-polar" height of 265mm. What really amazes me is that you can slide the magnets onto eachother simply as nothing, needs no force at all and you barely notice that they even want to retract eachother sideways and they barely attract eachother either. Isn´t this strange? there should be a strong force or else the magnets are really weak?
I even read in another forum where Saturnus said that they will stick togheter superstrong and the glue was there "just in case". Have they changed the woofers for the worse?
 
Found it! It saw on the assembly instruction for the AMP6-B acctually=)

I drove to Ljudia yesterday and bought the 4x HP-10W by the way....when i got home and tested them two of them had defects!! It almost seems like the cone is made of dual layers of paper and that there is no glue in between, resulting in a rattling/broken sound when playing bass. Ever thumping on the cone with your fingers generat this rattling sound. I´m replacing them in the end of the week.

Another thing i noticed is that the total height of HP-10W is 132,5mm resulting in a total "bi-polar" height of 265mm. What really amazes me is that you can slide the magnets onto eachother simply as nothing, needs no force at all and you barely notice that they even want to retract eachother sideways and they barely attract eachother either. Isn´t this strange? there should be a strong force or else the magnets are really weak?
I even read in another forum where Saturnus said that they will stick togheter superstrong and the glue was there "just in case". Have they changed the woofers for the worse?

Seems like you got some dodgy drivers there. The magnets should indeed be very strong. Have you tried with a screwdriver? Btw, you need to remove the sticker on the back to get the real magnetic connection between the two magnets but even without doing that if you stack them on top of each other magnet to magnet you should be able to lift the bottom one with the top one.
 
Is it possible they have changed the specs?
-The weight of one woofer is 2.7kg witch gives a total of 10,8kg. (and not 14kg)
-The height of the woofer is smaller than Saturnus ones.
-If i stack them together and lift the top one it almost like they repell eachother and helping me lift the top one.

As i see, this can´t be some faulty fabrications as i have four of them with same weight and as they give equal SPL (measured by my ear) they must have cut the costs on these?. Im just feeling i wont be making a "hell of a blaster" with these ones compared to the drivers you guys seems to have gotten. Anyone else notising the same maybe?
 
Am I ready?

Hi,

I'm about to build a smaller version of the boominator, I got these things, am I good to go?

2x HP-10W
2x Zomax piezo tweeters (Like saturnus')
1x Pre-assembled AMP6-Basic
2x 5w 150ohm resistors (for tweeters)
1x on/off button
2x bass reflex tubes 6,6 cm diameter
and of course some appropriate wood for building.
+misc. accessories, like corners and speaker protection, car battery.

Anything you guys would say I am missing?

I know that I cannot go for 4ohm since I only have 2 speakers, but I think I will manage.
 
Is it possible they have changed the specs?
-The weight of one woofer is 2.7kg witch gives a total of 10,8kg. (and not 14kg)
-The height of the woofer is smaller than Saturnus ones.
-If i stack them together and lift the top one it almost like they repell eachother and helping me lift the top one.

As i see, this can´t be some faulty fabrications as i have four of them with same weight and as they give equal SPL (measured by my ear) they must have cut the costs on these?. Im just feeling i wont be making a "hell of a blaster" with these ones compared to the drivers you guys seems to have gotten. Anyone else notising the same maybe?

Well, since the physical measures seem to be correct with what you find in the specification. Then the sound measurements you can also find should also be correct so it would not make a huge difference. But it does screw up the dimensions a bit.
 
Hi,

I'm about to build a smaller version of the boominator, I got these things, am I good to go?

2x HP-10W
2x Zomax piezo tweeters (Like saturnus')
1x Pre-assembled AMP6-Basic
2x 5w 150ohm resistors (for tweeters)
1x on/off button
2x bass reflex tubes 6,6 cm diameter
and of course some appropriate wood for building.
+misc. accessories, like corners and speaker protection, car battery.

Anything you guys would say I am missing?

I know that I cannot go for 4ohm since I only have 2 speakers, but I think I will manage.

Everything you didn't think off ;)

EDIT: Oh, and congrats on getting the piezos. There's actually only 2 left in Europe at all the official importers combined and it's gone out of production. So no more standard Boominators.
 
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Hi guys..
I just have a quick question, since im a little uncertain about how to connect the amp6-b to my carbattery. Since im using a carbattery, like everyone else I guess, do I just connect the amp6 to the carbattery with two wires?

Is it the + and GND in the upper left corner of the picture that I connect the battery to?

An externally hosted image should be here but it was not working when we last tested it.


Thanks

/Odelheim
 
hi all. hi saturnus. very thanks to all of you for the great inspirations and the soulful experience you're transmitting...

- saturnus, i'm humbly asking your permission to start a boominator project of mine

planning to build a boominator inspired boombox with two 4ohms in series plus two 4ohms in series coax speaker. their specs: http://www.hertzaudiovideo.com/Doc/pdf_ecx690.pdf
- the amp will be arjen helder ta2020 mkiii.
- the housing will be blirch plywood, 12mm. two sloped boxes with triangle sizes - in a backpack.
- looks like i will need a 52liter volumes to match speaker's fs in a dipole configuration. too much! what if i do closed box and add fiberwool to virtually raise volume?

why my magnets don't exactly match when they're touching? i have to force them to be precisely matching in all points - else they collide but with a lag of two centimeters.

any other help is welcome.

and obviously, thanks
 
300x300x900mm

All outer ply is 12mm. Bracing is 8mm. Center volume is 66mm wide.

That gives 23L total volume when all drivers, ports and bracing volume is deducted.

I'm trying to calculate the dimensions for one speaker enclosure of a Boominator from the volume and measurements you mention, but I can't get it right.

Please correct me if I'm wrong...

When the plywood and center compartment is deducted, I calculate the volume of one enclosure to be ~30,2 liters.

Deducting the speakers (~2*1,4 liters) I get ~27.4 liters.

The piezos are maximum 0.2 liters in total.

I calculated the middle bracing volume to be 0.86 liters. If maybe half of this is cut away to make the two speakers share the enclosure, it is 0.43 liters.

The port I would estimate to be maybe ~0.2L depending on how you cut the plywood used for it.

So in total I get ~26,4 liters available in an enclosure. Where do the remaining 3.4 liters disappear to?
 
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I wrote a little earlier that the driver takes up 2.1 liter each. Going back to check my notes it's actually 2.6 liter each.

The port assembly takes up 2/3rds of an end wall so just calculate with 20mm ends.

The center bracing isn't cut that much out. Calculate it with taking up about 7.5mm (if it's 9mm thick).

so for each side

length = 450 - 42 (center compartment including 9mm walls on each side) - 20 end = 388mm

width = 300 - 31.5 (sides and center brace) = 268.5mm

height = 300 - 24 (top and bottom) = 276mm

total volume = 3.88 * 2.685 * 2.76 = 28.8 liter

net volume = 28.8 - 5.8 (all drivers including tweeters) = 23 liter