I am going to build one myself with a 10 dollar tripath 25W amp. 50 hours on a standard battery? That's a lot of Combichrist!
Almost this one, without the box:
http://cgi.ebay.com/Excellent-2-1-C...66:2|39:1|72:1205|240:1318|301:1|293:1|294:50
I am thinking about a mono bass 12" driver on one channel and another channel with a 90's low-fi panasonic 3-way speaker with 10", 4", 2" drivers. Power is from a normal sized 12V battery.
I really don't care about hifi, not even about stereophonics. I guess we can't play 60's beatles with guitars on one channel and drums on the other. As if we would want to on the best synth festival in Scandinavia - The Arvika Festival! Fy fan!
Almost this one, without the box:
http://cgi.ebay.com/Excellent-2-1-C...66:2|39:1|72:1205|240:1318|301:1|293:1|294:50
I am thinking about a mono bass 12" driver on one channel and another channel with a 90's low-fi panasonic 3-way speaker with 10", 4", 2" drivers. Power is from a normal sized 12V battery.
I really don't care about hifi, not even about stereophonics. I guess we can't play 60's beatles with guitars on one channel and drums on the other. As if we would want to on the best synth festival in Scandinavia - The Arvika Festival! Fy fan!
Hi Rewind,
Those 3 channel amps are class A/B, they don't use the Tripath TA2020 chip and they are not class D so they will be less than 30-50% efficient. The Class-D are up to 90% efficient. There is some more details of the chips they use in this description:
http://cgi.ebay.com.au/New-Lepai-LP...8819dc09d&_trksid=p3286.c0.m14&_trkparms=65:1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50
col.
Those 3 channel amps are class A/B, they don't use the Tripath TA2020 chip and they are not class D so they will be less than 30-50% efficient. The Class-D are up to 90% efficient. There is some more details of the chips they use in this description:
http://cgi.ebay.com.au/New-Lepai-LP...8819dc09d&_trksid=p3286.c0.m14&_trkparms=65:1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50
col.
That's good to know, because I almost ordered one of those instead. I actually have the two channel tripath version TDA2030. I do need a basschannel så I will only use one channel for a 12" driver.
I wonder how loud a 12" bass driver with 91dB/W on a 25W tripath will get. And is the 50 hour batterylife on a 550mAh battery correct?
I wonder how loud a 12" bass driver with 91dB/W on a 25W tripath will get. And is the 50 hour batterylife on a 550mAh battery correct?
Hey guys, I see my pet project is still making a stir. 
I'm sorry I haven't been around to answer many questions lately. But in the next couple of days I'll back check and answer a few of those I can answer.
Firstly regarding the resistors on the piezos, they don't have to be the value I used unless you use the exact piezo use. The value can be calculated as the capacitance of the piezo and the resistor form a high pass filter, that should have a corner frequency of about 3.5-4KHz. High quality piezo like the ones I used generally but not always have much higher capacitance than low cost piezo so the resistor is of much higher value. I recommend NOT using wirewound resistors at all, these have much too high serial inductance, and in series with a piezo that forms a low pass filter. Even Dale's super expensive "non-inductive" wirewound power resistors have too high series inductance. Use 3W carbon or metal film resistor instead, or several low wattage resistors in parallel.
I'm sorry I haven't been around to answer many questions lately. But in the next couple of days I'll back check and answer a few of those I can answer.
Firstly regarding the resistors on the piezos, they don't have to be the value I used unless you use the exact piezo use. The value can be calculated as the capacitance of the piezo and the resistor form a high pass filter, that should have a corner frequency of about 3.5-4KHz. High quality piezo like the ones I used generally but not always have much higher capacitance than low cost piezo so the resistor is of much higher value. I recommend NOT using wirewound resistors at all, these have much too high serial inductance, and in series with a piezo that forms a low pass filter. Even Dale's super expensive "non-inductive" wirewound power resistors have too high series inductance. Use 3W carbon or metal film resistor instead, or several low wattage resistors in parallel.
Secondly, the concept behind the Boominator depends 2 things mainly. The bipolar design which means a lot of leveling over the frequency band comes is completely automatic since there no baffle step to consider. And then a little trick I discovered after having built several test cabinets. If you calculate a standard optimal bass reflex cabinet for whatever driver you use with the optimal Q=0.7 tuning, and you then divide Vb with PI, and multiply Fb with the squareroot of 2, you end up with the optimum tuning for outdoor use Q=1.2, and you get rid of all those bass frequencies you can't play loud enough to be audible outdoors anyways, and at the same time the rise towards the cut-off frequency equalizes the bass to a more or less flat level when used outdoors.
My Version
Here is a picture of my version of the boominator. I'm very happy with it. I need to take more pictures to give you all a better view. My only complaint is that is weighs 48lbs (22kg), but that was to be expected.
I'm using the port handles plus a removable strap. The entire box is epoxied together (no screws) except for the lid whick is bolted on so I can get in and out as needed.
It sounds great and just fits in the back of my car under the cargo cover.
Aron
Here is a picture of my version of the boominator. I'm very happy with it. I need to take more pictures to give you all a better view. My only complaint is that is weighs 48lbs (22kg), but that was to be expected.
I'm using the port handles plus a removable strap. The entire box is epoxied together (no screws) except for the lid whick is bolted on so I can get in and out as needed.
It sounds great and just fits in the back of my car under the cargo cover.
Aron
Hi everyone,
I'm recently started to plan a boombox as well, only problem being that I'm a complete newbie when it comes to audio electronics. I hope some of you will answer a few questions I've thought of. I think I know some of the answers already, but I really have to ask them anyway to be sure.
1) How are these speakers configured exactly? I think that it is 2 drivers parallel per channel, so 2x8 ohms = 4 ohms. What about the piezo tweeters? Are they also in same parallel configuration? How come they don't add up in the calculated ohms?
2) Would this one do for the 0.22 mH coil? http://www.ljudia.fi/lisatarvikkeet-s82136/komponentit-s82140/kelat-c79503/kela-020-mh-p79506/ How exactly are the coil and the resistor installed anyway?
3) Is there any good resource for studying how to tune the enclosure? All these terms like Qbox of 1.1 tuned at 82 Hz and how to calculate the box volume is compeletely unknown to me.
Thank you for your patience and answers!
I'm recently started to plan a boombox as well, only problem being that I'm a complete newbie when it comes to audio electronics. I hope some of you will answer a few questions I've thought of. I think I know some of the answers already, but I really have to ask them anyway to be sure.
1) How are these speakers configured exactly? I think that it is 2 drivers parallel per channel, so 2x8 ohms = 4 ohms. What about the piezo tweeters? Are they also in same parallel configuration? How come they don't add up in the calculated ohms?
2) Would this one do for the 0.22 mH coil? http://www.ljudia.fi/lisatarvikkeet-s82136/komponentit-s82140/kelat-c79503/kela-020-mh-p79506/ How exactly are the coil and the resistor installed anyway?
3) Is there any good resource for studying how to tune the enclosure? All these terms like Qbox of 1.1 tuned at 82 Hz and how to calculate the box volume is compeletely unknown to me.
Thank you for your patience and answers!
Hello again,
couple hours of vigorous Googling explained question 3 to me for some part, I now know how to calculate and tune enclosures based on the values of a single element.
And here's some follow-up questions:
4) What if there's two elements in one enclosure?
5) What if the two elements are different ones?
6) How do the piezo tweeters change the situation?
7) Why did Saturnus choose 82 Hz for the boominator?
Another thousand thanks for the replies.
couple hours of vigorous Googling explained question 3 to me for some part, I now know how to calculate and tune enclosures based on the values of a single element.
And here's some follow-up questions:
4) What if there's two elements in one enclosure?
5) What if the two elements are different ones?
6) How do the piezo tweeters change the situation?
7) Why did Saturnus choose 82 Hz for the boominator?
Another thousand thanks for the replies.
I can't edit my posts, so I'll have to make a new one...
4) and 5)
It seems that if I use two of the same elements, enclosure volume doubles, if they aren't in the boominator style magnet-to-magnet configuration, which would actually require ½ of the volume.
Correct?
Using two different elements would require separate enclosures for optimal results.
I plan to use a pair of 8 ohm P.Audio HP10W+piezo together with elemetns from old 8 ohm 2-way reflex speaker that I have to save some money, so this would require separate enclosures for the main elements, even though they would be put in parallel for each amp channel.
Is this a particularly bad idea, since the old 8 ohm 2-way speaker is not very sensitive, only 90db and would require crossover as well?
Thanks!
ps. 6) and 7) are still without answers...
4) and 5)
It seems that if I use two of the same elements, enclosure volume doubles, if they aren't in the boominator style magnet-to-magnet configuration, which would actually require ½ of the volume.
Correct?
Using two different elements would require separate enclosures for optimal results.
I plan to use a pair of 8 ohm P.Audio HP10W+piezo together with elemetns from old 8 ohm 2-way reflex speaker that I have to save some money, so this would require separate enclosures for the main elements, even though they would be put in parallel for each amp channel.
Is this a particularly bad idea, since the old 8 ohm 2-way speaker is not very sensitive, only 90db and would require crossover as well?
Thanks!
ps. 6) and 7) are still without answers...
6) Piezo Tweeters won't need their own enclosure. You can put them in one of the other enclosures and just subtract the volume of the tweeter from the volume of the enclosure since that will slightly effect your woofers. You will need to crossover the piezos which is slightly different than regular tweeters, but there is good information to be found in this thread (combined with some google searching) and they are working well on my setup.
7) I think Saturnus chose 82Hz because low low bass won't carry outside in a noisy environment anyway (I chose 80Hz). He also mentioned 82Hz was a nod to 41Hz.com, the amplifier company (2x41=82).
I probably would not use two different woofers. It will be much simpler with matching speakers and I think the sensitivity will be lacking if you use an amp like the AMP6 Basic.
Aron
7) I think Saturnus chose 82Hz because low low bass won't carry outside in a noisy environment anyway (I chose 80Hz). He also mentioned 82Hz was a nod to 41Hz.com, the amplifier company (2x41=82).
I probably would not use two different woofers. It will be much simpler with matching speakers and I think the sensitivity will be lacking if you use an amp like the AMP6 Basic.
Aron
ZOTA, nice looking ghettoblaster. Which speakers have you chosen?
Anyone here done a ghettoblaster with 24V? im planning on going for it with sure-electronics 2x100W amplifier, but i noticed a problem. While using two 12V batteries in series, the voltage of the other battery always drops faster then the other ones. Any way gettin around it?
Cheers
Anyone here done a ghettoblaster with 24V? im planning on going for it with sure-electronics 2x100W amplifier, but i noticed a problem. While using two 12V batteries in series, the voltage of the other battery always drops faster then the other ones. Any way gettin around it?
Cheers
Thank you for the reply, Zota!
Good to know that I don't have to calculate anything separate for the piezo besides it effect to the driver by eating some space from the it's enclosure.
Conserning 6)
I understand that crossover is not really that necessary for the piezo, just use a resistor. I don't know exactly how big resistor, Saturnus says 150 ohm, other say different values. I probably just use 100 ohm and listen how it sounds.
Conserning 7)
Oh I see, that sounds like a smart thing to do. I just don't find anywhere this Qbox value for simulations (I use winISD).
About the sensitivity issue, do you just mean that AMP6B would prefer speakers with 94db+ sensitivity, not anything related specifically using two different drivers?
Good to know that I don't have to calculate anything separate for the piezo besides it effect to the driver by eating some space from the it's enclosure.
Conserning 6)
I understand that crossover is not really that necessary for the piezo, just use a resistor. I don't know exactly how big resistor, Saturnus says 150 ohm, other say different values. I probably just use 100 ohm and listen how it sounds.
Conserning 7)
Oh I see, that sounds like a smart thing to do. I just don't find anywhere this Qbox value for simulations (I use winISD).
About the sensitivity issue, do you just mean that AMP6B would prefer speakers with 94db+ sensitivity, not anything related specifically using two different drivers?
whelibob,
I used four of the Eminence Alpha 8A's from parts express.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-401
Using 8 inch speakers (especially these) let me build a smaller enclosure that would fit in the back of my car with the cargo cover over it. Unlike many Americans, I have a small European hatchback with a small trunk.
Gaichuke,
This is where I got some of my piezo crossover info.
http://www.planet10-hifi.com/piezo-XO.html
---I understand that crossover is not really that necessary for the piezo, just use a resistor. I don't know exactly how big resistor, Saturnus says 150 ohm, other say different values. I probably just use 100 ohm and listen how it sounds.
I'm not sure about the two drivers specifically (it seems less than ideal to me, but I'm not sure), so I'll defer to others. To get good usable volume out of the AMP6B for outdoor situations 94db+ would be better.
---Conserning 7)
Oh I see, that sounds like a smart thing to do. I just don't find anywhere this Qbox value for simulations (I use winISD).
About the sensitivity issue, do you just mean that AMP6B would prefer speakers with 94db+ sensitivity, not anything related specifically using two different drivers?
Aron
I used four of the Eminence Alpha 8A's from parts express.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-401
Using 8 inch speakers (especially these) let me build a smaller enclosure that would fit in the back of my car with the cargo cover over it. Unlike many Americans, I have a small European hatchback with a small trunk.
Gaichuke,
This is where I got some of my piezo crossover info.
http://www.planet10-hifi.com/piezo-XO.html
---I understand that crossover is not really that necessary for the piezo, just use a resistor. I don't know exactly how big resistor, Saturnus says 150 ohm, other say different values. I probably just use 100 ohm and listen how it sounds.
I'm not sure about the two drivers specifically (it seems less than ideal to me, but I'm not sure), so I'll defer to others. To get good usable volume out of the AMP6B for outdoor situations 94db+ would be better.
---Conserning 7)
Oh I see, that sounds like a smart thing to do. I just don't find anywhere this Qbox value for simulations (I use winISD).
About the sensitivity issue, do you just mean that AMP6B would prefer speakers with 94db+ sensitivity, not anything related specifically using two different drivers?
Aron
Yet another question...
This time regarding the bipolar design in boominator. It's true that you get almost 360 degree of music blasting, but you can only be on one side of the thing itself.
So doesn't this design "waste" half of the power because you can only music mostly from two speakers at a time?
Or does the increased sensitivity of bipolar design cancel this?
I'm now contemplating on bipolar design, but I'm afraid that I'm loosing half of the power to the people behind the boombox.
What do you think?
This time regarding the bipolar design in boominator. It's true that you get almost 360 degree of music blasting, but you can only be on one side of the thing itself.
So doesn't this design "waste" half of the power because you can only music mostly from two speakers at a time?
Or does the increased sensitivity of bipolar design cancel this?
I'm now contemplating on bipolar design, but I'm afraid that I'm loosing half of the power to the people behind the boombox.
What do you think?
New 12v boombox project for boat
Hi,
Am totally new to audio/electronics, but just read all 16 pages of this thread. Some is clear to me, some still makes no sense at all, great reading though.
I have a boat in Amsterdam that I want to build a 12V battery powered soundsystem for (the motor does not provide output power).
I am not so worried by looks, absolute sound quality or absolute noise at this stage, just some reasonable sounds to cruise to. While still learning something and getting to play around of course! And I am sure I will want to develop something better over time...
I already have a Lepai LP-2020 amp which I intend to use for this project, currently running off a 12V, 1.2amp dc power supply. I have a 40ah marine battery to power it.
I have some old Sony SS-H 2800 6-ohm 80w bookshelf speakers sitting around that I was going to use for phase 1. I have no idea what their sensitivity is.
As I was planning to test it this weekend I was going to put together something quickly. I am assuming I can just put a fuse inline between the positive battery terminal and connect the power up to the amp...is it this simple?
I was planning on using a 2amp fuse, is this enough?
Round 2 will involve some better speakers... I have found some P Audio HP-10W's for €28.50 each which seems reasonable.
http://www.yatego.com/konoline/p,4a...r-hp-10w?sid=09Y1246466745Y1b1fc6aa2df091535c
The website mentions they are 4-8ohm, what does this mean, can you choose or are they variable? I understand 4-ohm would be better for my amp.
Can these be used without tweeters, or is it better sound to use them?
Will a combo of 2x high-sensitivity tweeters and 2x HP-10W's suit the Lepai LP-2020? I am only looking at having sound coming from 1 side at this stage...no boominator just yet!
Many thanks,
-Vincent
Hi,
Am totally new to audio/electronics, but just read all 16 pages of this thread. Some is clear to me, some still makes no sense at all, great reading though.
I have a boat in Amsterdam that I want to build a 12V battery powered soundsystem for (the motor does not provide output power).
I am not so worried by looks, absolute sound quality or absolute noise at this stage, just some reasonable sounds to cruise to. While still learning something and getting to play around of course! And I am sure I will want to develop something better over time...
I already have a Lepai LP-2020 amp which I intend to use for this project, currently running off a 12V, 1.2amp dc power supply. I have a 40ah marine battery to power it.
I have some old Sony SS-H 2800 6-ohm 80w bookshelf speakers sitting around that I was going to use for phase 1. I have no idea what their sensitivity is.
As I was planning to test it this weekend I was going to put together something quickly. I am assuming I can just put a fuse inline between the positive battery terminal and connect the power up to the amp...is it this simple?
I was planning on using a 2amp fuse, is this enough?
Round 2 will involve some better speakers... I have found some P Audio HP-10W's for €28.50 each which seems reasonable.
http://www.yatego.com/konoline/p,4a...r-hp-10w?sid=09Y1246466745Y1b1fc6aa2df091535c
The website mentions they are 4-8ohm, what does this mean, can you choose or are they variable? I understand 4-ohm would be better for my amp.
Can these be used without tweeters, or is it better sound to use them?
Will a combo of 2x high-sensitivity tweeters and 2x HP-10W's suit the Lepai LP-2020? I am only looking at having sound coming from 1 side at this stage...no boominator just yet!
Many thanks,
-Vincent