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PostPosted: 21 Sep 2015, 08:56 
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Joined: 28 Dec 2010, 22:07
Posts: 352
Hello all.

I'm looking at some kits on Ebay that might help me pass the time. I am on extended business travel (or something like that) and don't have access to my full work shop. However, I am decently resourceful and can improvise.

I have seen some kits on Ebay and am curious if anyone else has experienced them. There are tons out there (I imagine that tons is literal) and they are stupid cheap. I want to buy one, solder it up, and see if it is any good. Below is a link to one that I might look at getting. If it works well, I could see myself getting another one and using it to power 4 ohm speakers in a small enclosure something like a sound bar.

http://www.ebay.com/itm/TDA2030A-Audio-Power-Amplifier-Board-DIY-Learning-Kit-PCB-Board-15W-/181385570927?hash=item2a3b6c2a6f

I've gone the tube route before. My current stereo amp uses a 6U8A and two EL84s (...well...6P14Ps) and I get about 11 watts per channel. This is with Heyboer output transformers and an Antek toroid for the power transformer. The whole thing was more $$ than I would feel comfortable spending again. I like the idea of making great-sounding power amplifiers, just not with $250 in iron and copper and another $100 in tubes.

Ed

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PostPosted: 21 Sep 2015, 11:53 
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Joined: 06 Apr 2009, 10:08
Posts: 1626
Location: US Pacific Northwest
Most of these kits are simply the reference circuits included in the data sheets for the part. As such they usually have fairly good performance for most applications. This one looks like they even used the board layout from the data sheet. The only question I have is that the vertical version of the TDA2030A hasn't been produced since 2011. It was replaced by the horizontal Pentawatt version package. So you might want to be careful about what amplifier part you are actually getting.
Attachment:
Screen Shot 2015-09-21 at 9.44.16 AM.jpg

Most modern chip amps are very good (if a little bright) and this board, married with a decently quiet power supply should give reasonable good sound. And you certainly can't beat the price.


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PostPosted: 21 Sep 2015, 16:57 
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Joined: 28 Dec 2010, 22:07
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I work in an electronics repair shop and I have also thought about getting these purely for the sake of training new guys on soldering. Granted, in our line of work, we solder only wires and coax connectors. Still, if you can dodge a wrench...

I would have been thrilled to have one of these in 2008 when I was just starting out in electronics. I had a specific book that included several designs for a transistor power amplifier. I also found that the guy who wrote the book wasn't exactly an expert, as evidenced by his vacuum tube amplifier that would NOT work as shown in the book.

Nonetheless, the new guys might get a kick out of building something that turns out to be a stereo they can use. It would give them satisfaction to know they made it themselves. Also, I've used TDA2030s (or other, similar chips) from China and had no problem. I didn't pump full power into them but I did get them to work well.

Ed

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PostPosted: 02 Oct 2015, 08:38 
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Location: Australia
Certainly cheap enough. Married to some high efficiency speakers could produce good volume if not the perfect sound.

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PostPosted: 15 Sep 2019, 01:50 
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Joined: 28 Dec 2010, 22:07
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I revisited this kit four years after building it (I've never actually put music thru it). Here's what I found.

First, this is the kit I have:

https://www.ebay.com/itm/DIY-Kit-2-0-Du ... %7Ciid%3A1

I fired up one channel into an 8 ohm load resistor. At 12.0v (supply), clipping occurs just over one watt. I increased the supply voltage to 24.0v and got roughly 5.3 watts into 8 ohms. The supply current was something like 440 mA. This isn't terrible efficiency but not great. If it were me, I'd buy individual boards and place them 4-5 cm (a couple of inches) apart in the chassis so heat wouldn't affect one channel from the other.

The sound was great. I don't have stellar speakers but it brought out the best in what I had. Granted, I was using about 10 cm of 24 AWG wire (stolen from a CAT-5 ethernet cable) for power leads, and about 30 cm of the same for speaker leads.

Here's one thing I would change about the amp - the main filter cap is a 2200 µF 25v model. I think it should be a 35v cap. At lower voltages, the power output isn't impressive (effectively, I was running it at +/- 12v, which isn't much as far as power amplifiers are concerned). With a supply of 30v, it's very possible this amp could put 10 watts into 8 ohms.

I would highly recommend this amp kit, especially at the ridiculously low price. I'd just recommend some changes.

Ed

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PostPosted: 15 Sep 2019, 21:47 
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Joined: 23 Feb 2017, 02:02
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The headamps I had designed that runs on +-12v typically swing within 1.5V to the rails.
It can at least output 2v to each rail.

This means a voltage of +-10v is possible. 20v pk-pk

Peak power is V^2/R = 10^2/8 = 12.5W peak into 8R
and 6.25W RMS into 8R (12.5/2)

The IC chips typically have allot of internal circuit to limit the maxium output current and prevent blow ups when output is shorted so it can't swing to rails.


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