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Old 13th November 2012, 06:34 PM   #3311
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Originally Posted by Saturnus View Post
The 0.47uF is the optimum for with the 22Kohm input impedance of the amp6b (unless modified). The amp9b has 50Kohm input impedance.

I'd recommend something like 0.1uF for the amp9b. It shouldn't affect bass performance in any way, just limited cone movements you can't hear anyways. In fact, if anything it should result in even better midrange.
Is this also the right size of input caps if I parallel connect the outputs on amp9?
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Old 13th November 2012, 07:39 PM   #3312
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Originally Posted by radermacherdk View Post
Is this also the right size of input caps if I parallel connect the outputs on amp9?
Yes. There's no difference.
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Old 13th November 2012, 07:46 PM   #3313
joeoz is offline joeoz  Australia
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Originally Posted by larzman View Post
Joeoz - I like the sounds of your passive preamp idea. I looked at the circuit on the link you provided (thanks) and it's super simple to build. However, I'm wondering about the audio quality after running through a transformer rated at 300~10kHz. How does it sound? Are the bass and high notes subdued? Would a better transformer help?
Hi larzman,

I didn't have much time to test out the preamp, but it sure did sound good and I didn't notice anything missing from the music I regularly listen to.

Regarding the transformers, I used a pair of these:

http://www.jaycar.com.au/productView.asp?ID=MM2532

Which seem equivalent to those mentioned in that article. Not sure which other transformers could be used here, as I've only been able to find these (locally in Australia).

Why not give it a try and see how you go? A very quick and easy project.

Cheers,
Joe
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Old 13th November 2012, 07:49 PM   #3314
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Originally Posted by Saturnus View Post
Yes. There's no difference.
Thank you very much, for the quick response and this very interesting and great project

Last edited by radermacherdk; 13th November 2012 at 07:57 PM.
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Old 16th November 2012, 07:09 PM   #3315
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Originally Posted by larzman View Post
Daniel, Sounds good, but I would simply use a charge controller as any I've seen or designed always had the reverse diode. Heck, a lot of panels have one (diode) built inline with it's output wires. It also protects the battery from overcharge or overdraw. Both of those will seriously shorten battery life or worse.
I'm having 3 problems with the CMP solar charge controller. Basically, its a wonderful little black box with a little blue voltage trimmer inside for voltage setting. Also inside is a chopper style voltage regulator and battery monitor. But, there is no current limiter.

So far, I've been able to smooth the chopping and defeat the battery monitor drain by hooking up a 10,000u 25v cap to the spot marked battery charge and then a schottky diode series to the + battery charge line.

Now, it charges and monitors the cap which also smooths the chopping and the battery monitor cannot slowly suck charge out of the battery due to the series schottky. Total voltage drop is a mild 0.8v. Good patch!!!

Meanwhile, back to my simple zener based regulation. Yesterday, I finally got full sun, which is rare in winter. My dorky little plastic 5w solar panel managed to burn out a 15v zener 1w zener diode AND burn my fingers with only the difference between 14.9v zener to 20.8v panel. The "12v" panel was THAT strong in the high range. It is also far stronger in the low range. I'm redoing the circuit to use a zener array and will soon find out how many zeners with how many resistors it takes to pull down a 5w solar panel in full sun so that it never passes ~14.8vdc. It should be possible to calc that example for ~13.5vdc too. It would take 2 such zener arrays for 10w or 4 for 20w solar panels. This simple circuit has kept its advantage in the shade (no waste whatsoever); however, getting it to work in full sun is not yet complete.

And now back to the CMP charge regulator:
The newly patched CMP (parallel cap and then series schottky at output) has zero battery drain and greatly reduced ripple; however it still doesn't have a current limiter. If someone hooks that up to a 20 watt solar panel in FULL sunlight and a drained battery, there's still no current limiter present to protect the battery against enough force to destroy a ride-on lawnmower battery.

For either the CMP chopper or my zener loads, neither of which have a current limiter, surprising a drained battery with a solar panel in full sun would take a big heavy battery to withstand the blast of current. The current limiter in both cases IS the solar panel, which is. . . backwards because it works fine on cloudy days but nukes batteries in full sun.

Questions:
How do we limit the current to the battery without limiting the current to the amp? A fixed current limiter seems inappropriate in case of a leaf or a cloudy day; however, the battery must be protected in case of full sun. I'm a bit stuck.
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Old 16th November 2012, 07:32 PM   #3316
axebay is offline axebay  Sweden
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Planing to build a boominator this winter. Will go for the standard setup with 4 HP10,2 SLA 7,2Ah and an AMP6. The tweeters though I'm not sure about yet. I'd like to buy the tweeters at Ljudia since I'm ordering the HP10 from them. Unfortunatly they don't have PHT-407N but perhaps the PHT-409 will be ok with a first order filter?
Connecting a 12v to USB for cellphone charging shouldn't be problem?
I'd also like to have solar panels and a CMP charging controller for these. Which solar panels are currently the recomended ones for the boominator, none in the wiki?
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Old 17th November 2012, 10:01 AM   #3317
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I can only encourage to get the specially designed piezos that will be available from Home page around late January/early February next year.

As long as the cell phone in question is not the one playing music on the system at the same time that it is charging, it's not a problem. Besides cell phone manufacturers stress in the manual that charging a li-ion battery while you're actively using it will reduce the lifetime of the battery, so you shouldn't do that in anyways.

Again, canopysound has some very high quality Phocos solar chargers that I'd highly recommend. (Canopysound asks my advice on occasion on what to stock. I must stress that I get no commission for this.)

No solar panels are recommended simply because the choices are too many. Is it built-in or separate? How many nominal watts and so on. Only thing is that if you live north the 50th parallel as all of Scandinavia and the UK is. You must use thin-film panels also known as amorphous panels for non-fixed installations as these will have much higher average output.
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Old 18th November 2012, 11:22 AM   #3318
axebay is offline axebay  Sweden
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Originally Posted by Saturnus View Post
I can only encourage to get the specially designed piezos that will be available from Home page around late January/early February next year.

As long as the cell phone in question is not the one playing music on the system at the same time that it is charging, it's not a problem. Besides cell phone manufacturers stress in the manual that charging a li-ion battery while you're actively using it will reduce the lifetime of the battery, so you shouldn't do that in anyways.

Again, canopysound has some very high quality Phocos solar chargers that I'd highly recommend. (Canopysound asks my advice on occasion on what to stock. I must stress that I get no commission for this.)

No solar panels are recommended simply because the choices are too many. Is it built-in or separate? How many nominal watts and so on. Only thing is that if you live north the 50th parallel as all of Scandinavia and the UK is. You must use thin-film panels also known as amorphous panels for non-fixed installations as these will have much higher average output.
Ok, no problem waiting til February since I don't need to have the boominator ready until early June next year.

Do I need to use a diod to the solarpanels when I've a solar charger?
I'd like to have inbuilt solarpanels with not more watts than necesarry. As most other boominator builders I'll use mine at festivals and roskildes is the longest of them, 9 days. And I assume the boomiantor will be used as a bench so the panels need to be rigid?
You used 4x 2W panels in your first version and that was enough? If I'm not misstaking there's room for 3 7,2Ah batteries in the middle compartment, would you recomend that instead of spending the extra cost of one battery on more solar cells?
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Old 18th November 2012, 11:56 AM   #3319
axebay is offline axebay  Sweden
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These were recomended earlier in the thread Solar Cell Huge - 5.2W - Solar - Components - All you need to prototype . If I were to mount 2 of these on the boominator in series and one were blocked, would it stil be able to charge the battery. If not it would be a better solution to have 4 of Solar Cell Large - 2.5W - Solar - Components - All you need to prototype and mount 2 in series and paralell the pairs?
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Old 18th November 2012, 05:48 PM   #3320
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Had to build a new Amp9 yesterday. First testing today and it sounds ok. I'm not sure where to set filtering yet, but tried: lowpass cutoff 2500 and higpass cutoff 2000 Filtertype Bessel. Treble is cutting my eras.
some pic's: http://sdrv.ms/Q6Lwwv
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