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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th March 2011, 09:18 AM   #901
coit is offline coit  Australia
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Saturnus,what do you think of the Paudio PHT-406?
I can get them for $33 each,but they're 105dB.
Pad them down to suit the HP-10W?
thankyou
coit
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Old 8th March 2011, 05:30 PM   #902
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I'd recommend the PHT-407N instead. In my opinion it sounds nicer and doesn't have the strange peaks that needs to be dealt with that the 406 has.

The rising output toward the low end on the 407N is perfect for making a low order filter that has a very steep slope acoustically. What you do is choose a filter that is -3dB at XO, for example a first order butterworth (a single series cap), and put that XO on the low end of the peak, ie. ~2500Hz. What you get acoustically is basically a 6th order bessel filter with -6dB XO at ~2100Hz with perfect completely linear output and phase response. It will basically be almost within 1dB in frequency response almost to 20KHz, it's something like within +0.5/-1 dB.

Another reason that I'd chose the 407N over the 406 is that even though there's nominally only 10 degrees difference in coverage angle, it appears to be much more than that.

A third reason is of course weight. 200g vs. 900g each adds up to a difference of almost 3 kilos more with the 406s.

Fourth reason to chose the 407Ns is that if you have a 4 channel amp then you parallel connect the woofers and serial connect the tweeters to go 2 different channels per side. Doing this means the woofers are 4 ohms and the tweeters are 16 ohms. Together with the insertion loss of a PLLXO on the woofers channels the padding down of the tweeters is automatic and matches eachother. It also means the tweeter channels will consume next to no power but since they are serially connected they will have a power handling that easily matches the woofers even with a low order filter.

Last edited by Saturnus; 8th March 2011 at 05:52 PM.
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Old 13th March 2011, 09:23 PM   #903
ThokN is offline ThokN  Denmark
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I'm making another build for my GF's camp, and they want it ultra-cheap (<1000kr / <190$), so I will use only 2 speakers (still stereo, not back-to-back), and the sound-quality is not of importance, so I have found this amp:

SA-36A TA2020 Tripath Class-T Digital Amplifier HiFi on eBay (end time 20-Mar-11 04:01:55 GMT)

and these speakers:

SPM-200X/4

I've read something about these cheap china-amps but I get confused about people's arguments about these, so what do you think? Is it okay for a budget-boominator? Or is it possible that they use way more power than the great Amp6-B kits?

And also...does the speaker seem okay? I noticed they only go to 15.000Hz, but when I cut off @16.000Hz in Winamp, I barely notice any sound-quality loss, although I do @14.000Hz

Hope you can help
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Old 14th March 2011, 02:13 AM   #904
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BL of 3.9 and xmax of 1mm indicate poor bass performance - however relatively high SD gives a high efficiency of 94db (i think they have the wrong graph shown though - seems to be impossibly high for a 6.5" driver)

weight is 700g though so v light and at 35 quid its a decent enough deal

verdict - a loud efficient speaker that is bound to handle mid well, but will struggle at the bass end (no bass) and it wont sound all that crisp.. although - it will do the job
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Old 14th March 2011, 09:16 AM   #905
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Quote:
Originally Posted by zerokelvin99 View Post
BL of 3.9 and xmax of 1mm indicate poor bass performance - however relatively high SD gives a high efficiency of 94db (i think they have the wrong graph shown though - seems to be impossibly high for a 6.5" driver)

weight is 700g though so v light and at 35 quid its a decent enough deal

verdict - a loud efficient speaker that is bound to handle mid well, but will struggle at the bass end (no bass) and it wont sound all that crisp.. although - it will do the job
Maybe it's because it's an 8" driver
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Old 14th March 2011, 09:23 AM   #906
rubennn is offline rubennn  Denmark
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ThokN, I'm only using amplifiers from eBay and they are doing a great job. I dunno whether or not my amps use power in idle because they have a power switch, but it seems to follow the tripath power consumption very well. My stereo played 3,5 days last year on a 9 Ah battery with 10-14 hours playing time each day.

I'm very satisfied with these ebay amps but Saturnus said that they may be less fortunate when failing on you at the festival. Although I personally have not experienced anything at all yet (and I've been using them all year).

I think you could get a "decent" performance out of those Monacor speakers. Good enough for medium output listening. I've heard that these fullrange speakers with "doublecones" distort quite a bit when pushed to a limit. Somebody has to confirm that though
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Old 14th March 2011, 10:26 AM   #907
ThokN is offline ThokN  Denmark
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Thanks for your great responses!

I'm a bit worried about the lack of bass on the speakers, but since it seems ok to use such an eBay-amp, I save some money there instead of buying an Amp6 + enclosure + power switch + volume knob, so I might be able to choose a little bit better speaker. I will look into what BL and Xmas is to get a one with better bass.

Edit: Actually I think I will have the money for some piezo's and some bass/midrange drivers...that will probably give the best result. I think it will be these:
https://www.madisound.com/store/prod...oducts_id=8594
http://www.monacor.dk/produkter/hoej...-9/vnr/103980/

Thanks again, very helpful

Last edited by ThokN; 14th March 2011 at 10:37 AM.
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Old 15th March 2011, 12:09 PM   #908
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whoops, so it is

thokn: here is a great guide Speakerplans.com

Also worth looking into:

Vd (you want as high as possible, product of Xmax and Sd) and
Fs ideal 50-80hz
Qts anywhere in 0.28 - 0.45. you'll see in simulatons which work better for intended box sizes

you will need to simulate in "winisd" for ported enclosures
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Old 15th March 2011, 12:22 PM   #909
rubennn is offline rubennn  Denmark
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I actually have a question regarding the use of winISD.

Say you want to design another cheapo boombox as ThokN is about to. To calculate a port you need to fill in size of the port. Then there's a red or a green number, usually 0.xx (zero dot something). I guess when it's red it's not good and the other way around. But is it good to have a high number here? Like 0.8ish or so?

I'm I just babbling or does someone know what I'm talking about? :P
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Old 15th March 2011, 02:41 PM   #910
ThokN is offline ThokN  Denmark
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Zerokelvin99: Inspiring site you linked to! Great info, and I think we might build an X1 for next years festival to extend our Boominator!

I can't find the relevant data (Qts, Vd, Fs etc.) for the Monacor speaker unfortunately. Maybe someone in here has a guess on volume and port-size for those?


I have a quick question:
Does it matter where in the system I connect the solar panel? Close to the battery f.x.?
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