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Class D Switching Power Amplifiers and Power D/A conversion

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Old 16th November 2010, 04:36 PM   #771
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Find the new SketchUp drawing here. Please note that all I ask anyone using this design or anything that could concieabley be considered derivative of this design is that:

a) it's for non-commercial use only. You're not allowed to make and sell any for profit beyond a reasonable compensation for manual labour. If in doubt, ask first.

b) That you post pictures of your build either here directly or you place a link to photos of your build here.

That's all.

Now on to make the Signature edition.
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Old 17th November 2010, 08:40 PM   #772
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Quote:
Originally Posted by radiounix View Post
Saulty, I'm also planning to design a monophonic boombox with a cabinet dimension similar to yours, and I'm wondering if you still think the CTS/Motorola piezo tweeter is efficient enough to keep up with the Fatality driver you employed. How is the fidelity, and did you find it could cross over as low as 1.5k without issue? Basically, if you had to do it all over again, could you recommend said tweeter for the application?

Also, may I ask why you went for the far more expensive Class D Audio board over Hifimediy's, T3 1.0 tk2050/bt1597 Tripath board? I know that requires a 48v power source for maximum output, but in all other parameters, it does seem ideal.
I haven't spent enough time listening to it to say for sure. If anything, it may be 1-2db off on the high end but I'd need to add a second one to produce a +3db gain to see if it is really any better. I can say that when I paired them with the 10" goldwood woofers rated at 93 or 94, I did get some comments about those damn horns hurting people's ears. Probably the overall volume they were complaining about though. They may have been a little bright paired with 93db woofers. Also keep in mind that their frequency response isn't perfectly flat at 92db. http://piezosource.com/general/datas..._datasheet.pdf
It moves from 90-99 depending on frequency. Some people are applying a resistor to taper some of that peak that is noticed up in the 8khz range.
I don't think I'm going to make any more changes until I get some serious hours of listening with it. If I'm unhappy, I may apply the resistor and add a second one.
I went with the class D over the tripath purely for the extra headroom. In 99% of situations, I won't push more than 75W through it and a 2050 would be perfect. The Class D board with TI chip gives me a clean doubling of that before any real distortion for the 1% of times when I want the last 3db out of the system. That said, to save a good chunk of money, I'd suggest going the sure 2050 route with upgraded caps. $100 less and you can get away with 2 12V batteries vs. 3 saving a few more bucks. And 24v chargers seem to be a dime a dozen with all the electric scooters out there so you save a bit on the charger. I'd suggest taking the savings and building yourself a nice battery pack like the one Saturnus suggests below and shave off a few lbs.
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Old 24th November 2010, 12:54 AM   #773
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I spent some time listening and did some side by side comparisons against my version 1 build. The highs were definitely lacking. Everything seemed a bit cloudy compared to V1. So I pulled one of the piezo's from my original build and added it to the new build. Which should give the 1.8khz and up another 3db. The frequency response via iphone RTA came up a bit, but the actual sound improved remarkably. 3db at that frequency range is apparently very noticeable to the ear. That woofer really was too sensitive for the single piezo. Now it is a very nice balance.
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Old 28th November 2010, 08:20 PM   #774
kblnig is offline kblnig  Denmark
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i know the charger concerns have been discussed in this thread before, but i am still a little confused on the solutions available. I a have been looking at this

Mobil Solcelle sæt 13W - Bestil hos BilligCamping.dk

At the moment i got 2 12V, 7.2ah SLA batteries in parallell. Furthermore i have one of these

NEW Class T Amp TA2024 Amplifier Tripath Chip TA 2024 on eBay (end time 23-Dec-10 19:21:19 GMT)

according to the specs the input voltage should be between 12V-13.25V on the amp.. i Saw that saturnus said something about adding an extra 10% to that number. Does this manoeuvre apply to amps in general or just the amp6b?

The 13W solar panel charges the battery with 17.5V max and in this case i woldn't be capable of connecting the panel directly to the battery and the battery directly to the amp?

With the setup above what would you guys recommend..? Plug the panel directly to the battery and the battery directly to the amp, or is there any smarter and more safe solution?
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Old 28th November 2010, 08:43 PM   #775
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Originally Posted by kblnig View Post
With the setup above what would you guys recommend..? Plug the panel directly to the battery and the battery directly to the amp, or is there any smarter and more safe solution?
Exactly. The internal impeance in the batteries will make sure that the voltage never exceeds a safe voltage for the amp. But you should never connect the amp directly to the solar panels.
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Old 28th November 2010, 09:04 PM   #776
kblnig is offline kblnig  Denmark
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Originally Posted by Saturnus View Post
Exactly. The internal impeance in the batteries will make sure that the voltage never exceeds a safe voltage for the amp. But you should never connect the amp directly to the solar panels.
as always, thank you for the answer.. But to clearify this for me.. Will i then need a charger if i want the amp and then solar panel running at the same time or will it be alright if i couple it like this? (making a direct connection between the panel and the amp but with the battery in parrallel)

Click the image to open in full size.
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Old 28th November 2010, 09:18 PM   #777
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Quote:
Originally Posted by kblnig View Post
as always, thank you for the answer.. But to clearify this for me.. Will i then need a charger if i want the amp and then solar panel running at the same time or will it be alright if i couple it like this? (making a direct connection between the panel and the amp but with the battery in parrallel)

Click the image to open in full size.
It's safe to connect as illustrated.
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Old 29th December 2010, 11:57 AM   #778
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Hi Saturnus,

I currently run a similar boombox to yours, but i need to upgrade it as im not yet happy with it

i currently run on bass two of these

Beyma Speakers - Beyma 8BR40 8" speaker - Beyma 8BR40 100 watt 8" woofer for all hi-fi and studio monitor bass speakers. Beyma 8BR40 and other Beyma 8" speakers here.

with a sure 2*100 off a 24v SLA supply

however, i like bass. this is not enough bass. (music is mainly DNB / dubstep).

the rest of the setup is 2 more sure boards running two 6" mids and two APT80s (triamped off active Xover)

how would two of these run off an AMP-9 fare? or can you suggest another UK friendly bass sensitive (hitting 60-70 would be great) driver? ta!


http://www.fane-international.com/do...eign_10300.pdf


edit: or perhaps if i ran those 10's up to piezos with a single amp9? that would (MASSIVELY) improve battery life .. but SPL? hmmmmmmm

Last edited by zerokelvin99; 29th December 2010 at 12:08 PM.
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Old 29th December 2010, 01:58 PM   #779
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Why not get the HP10Ws I use. It's practically the only drivers in it's price range I can recommend. You can order them from any of the many European resellers since there's currently no UK reseller (as far as I know). It'll be about £80 including delivery for a pair.

An amp9basic will not put out more power as output power is determined by the laws of physics, ie. the supply voltage and load impendance, and since neither change, the output power won't change either. But you would have one 4 channel amp to drive the woofers and I'd recommend an active crossover or PLLXO crossing to a suitable horn directly on the other 2 channels.

Just going to the 10" woofers, either the HP10W or the one you link to, will give you about 4 times more output, ie. +6dB, just because they're that more sensitive.
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Old 29th December 2010, 02:30 PM   #780
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Quote:
Originally Posted by Saturnus View Post
Why not get the HP10Ws I use. It's practically the only drivers in it's price range I can recommend. You can order them from any of the many European resellers since there's currently no UK reseller (as far as I know). It'll be about £80 including delivery for a pair.

An amp9basic will not put out more power as output power is determined by the laws of physics, ie. the supply voltage and load impendance, and since neither change, the output power won't change either. But you would have one 4 channel amp to drive the woofers and I'd recommend an active crossover or PLLXO crossing to a suitable horn directly on the other 2 channels.

Just going to the 10" woofers, either the HP10W or the one you link to, will give you about 4 times more output, ie. +6dB, just because they're that more sensitive.
great, ill start hunting down some euro sellers

you mention the amp power being limited by the the laws of physics - but this class D amplifier Class D Audio TI-300 Amplifier - PRODUCTS

(another candidate, as mentioned earlier on in the thread - further up the page) puts out more power than the amp9, i take it pushes the voltage rails higher than Vsupply for the amp?

so, with this amplifier [or the bigger brother], 107db 1w1m high [two apt80s], and 98db 1w1m lowmid [two 10"s] should be a potent combo by my calculations
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