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Chip Amps Amplifiers based on integrated circuits

Modding the SMSL SA-36A Pro
Modding the SMSL SA-36A Pro
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Old 10th November 2016, 08:49 AM   #11
Konzentr8 is offline Konzentr8  United Kingdom
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As others have touched on the amp is rated for 15 v for a reason, although the chip can be used with higher voltages this has been limited in this amp mainly so Smsl can use the same chip in a more expensive amp with higher rated caps etc enabling a higher power rating.
I initially used mine with 12 v 5 a ( i don't trust cheap " in the box psu s ) and it sounded fine then in my ignorance tried a 24 v 4.5 a supply and fried it taking out the tweeters on my new JBL s at the same time.
Whilst i understand your enthusiasm for modding just make sure you understand exactly what you are doing or it will end in tears
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Old 10th November 2016, 02:19 PM   #12
brozium is offline brozium
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Quote:
Originally Posted by Konzentr8 View Post
tried a 24 v 4.5 a supply and fried it taking out the tweeters on my new JBL s at the same time.
So out of curiosity did you also have 16v caps and this is why you fried it? I mean I see what you are trying to tell me but if I do get better caps, what could the problem be? What should I be watching out for? I can always try the amp with some old speakers first as a "security measure".

That's why I was wondering about using a lower voltage, higher current amp. I've seen people mention that using astron psus made a big difference in sound. I currently only have a 12v 2A PSU laying around but I feel it sounds tiny. Actually, I feel the one I'm using now sounds "tiny" or like too "tight"? Don't know the exact words.
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Old 10th November 2016, 03:23 PM   #13
irribeo is offline irribeo  Netherlands
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Problem might be that not just the two big electrolytics could be rated below 25V, I don't know.
Your Teapo are general purpose series, low impedance or ultra low impedance/esr series should be better. Teapo have bad name because they tend to fail in stressfull positions in computers, here they could be fine, again I don't know. If only above 2 were available I would take the Teapo.
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Old 10th November 2016, 05:26 PM   #14
brozium is offline brozium
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So I did some calculations based on what I read on this thread and found out that:
Vpeak=sqrt(32w*8R)=16
Ipeak=16/8=2A
Cbulk=ipeak*td*dmax/vripple
=2A*1/250khz*0.95 / 0.1v = 76uf
cbulk 2 channels = 152uf
esrmax= 0.1/2 = 50mR

So I need at least 152uf for capacitance and a maximum esr of 50mR.
These OSCONs are 390uf and 14uR esr. So if I can fit 3 in there it would be the best option correct? I'm not completely sure how to set them up in parallel if they currently are in series but if they have the minimum capacitance there shouldn't be any problem.

Otherwise I could get a couple of these. and maybe just 1 OSCON.
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Old 10th November 2016, 06:32 PM   #15
brozium is offline brozium
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So I read up un how to solder them in parallel, basically I just need to put them through the same hole. I found These which are 20v 680uf and since my psu is 19v I guess that would be ok? I don't think I could fit 3 but my guess is 2 should do the trick in parallel. Am I going in the right direction?
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Old 10th November 2016, 06:35 PM   #16
irribeo is offline irribeo  Netherlands
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I get tired again thinking about then LOL Advice still remains the same as then, two large high frequency low impedance Chemicon electrolytics that fit comfortably and one solid polymer. If you can only get Teapo easily, go for Teapo. If you only can get Teapo 50uF solid polymer easily, add that value. Shipping can get ridiculous.

But what happened above in post #11 does make me wonder
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Old 10th November 2016, 06:44 PM   #17
brozium is offline brozium
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Originally Posted by irribeo View Post
two large high frequency low impedance Chemicon electrolytics that fit comfortably and one solid polymer.
Ok this seems doable. Just to clarify, the solid polymer one MUST be the same voltage as the others but it doesn't really matter if the capacitance is low as long as ESR is low.

Yeah it's 30usd to Mexico but thankfully I know someone in the US so I can ship it to them and then pick it up. I'm a bit eager to do this but I guess I can wait if I can get something better.

Quote:
Originally Posted by irribeo View Post
But what happened above in post #11 does make me wonder.
I know it scared me a bit but I'm guessing I should be ok if I do it correctly

Last edited by brozium; 10th November 2016 at 06:54 PM.
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Old 10th November 2016, 08:20 PM   #18
Konzentr8 is offline Konzentr8  United Kingdom
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Just for clarity i didn't make any changes my amp was as supplied , i just tried 24 v because i read that the chip could take 26 and assumed that Smsl were just limiting output by using / rating it at 15 v for marketing purposes .Obviously there are other components that play a part it made a loud squealing/cry for mercy then went silent. Next time i wired the Seakers up to a different amp tweeters were dead .
Live and learn as the saying goes
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Old 10th November 2016, 10:04 PM   #19
irribeo is offline irribeo  Netherlands
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I made a 3118 board with 16V Chemicon electrolytics and 16V Nichicon polymers and powered it with 24V powersupply and it started to pop sometimes while playing music, that surprised me a little till I figured it out Ampboard still seems to sounds the same as identical others, with a 15V PSU, the figuring what was going wrong maybe took one minute max. But the polymers probably are damaged inside.
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Old 11th November 2016, 02:21 AM   #20
PRR is offline PRR  United States
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> Vpeak=sqrt(32w*8R)=16

You have computed V RMS, not V Peak.

Peak of a Sine wave is 1.414 times higher. 22.6V.

In conventional single amplifiers, the power supply must cover the peak-to-peak, 45.2V.

These little class D modules give you *two* amplifiers per speaker. Each one can run on 22.6V (plus losses) and deliver the 45V p-to-p output.

Which is why it wants 25V DC supply to reach its 32W claim.

At 12.5V supply it would be 8W. At 18V about 16 Watts.

Remember that Double Watts is nowhere near Double Loud!!

But it does increase chance of break-down.
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