Chinese eBay parts amp build

[cobblers]

I'd been tempted to build an amp for ages, and I wanted something with a bit of power. After a few beers I decided to build one entirely out of bits ordered off chinese eBay, just to see how it would turn out.


I know it's cheating a bit, but Sure Electronics do some fairly well regarded class D amp modules, so I just bought one of those:

www.ebay.co.uk/itm/350542134444?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649



Then I needed a power supply. Ideally I wanted 36v (the max that the module can take) but I settled for 24v, with this:

www.ebay.co.uk/itm/110820555032?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648



Then I needed a case, so I took the measured dimensions and stuff and decided I could cram everything in this, and it would fit on top of a speaker nicely.

www.ebay.co.uk/itm/110908324070?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_1044wt_1163


And obviously I'd need a volume control, so while searching through a load of expensive potentiometers, I found an interesting digital volume thingy again from sure electronics, so I ordered that:

www.ebay.co.uk/itm/230646999349?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648#ht_5163wt_957



I had the binding posts, capacitors etc etc in stock cos I'm super cool like that. They were all cheap chinese stuff, but they were all pretty good.

Anyway, a couple of weeks later all my loot had arrives, so I set it all up on the bench and noticed one of the inductors in the power supply was wobbly, so I cracked the thing open to find it had completely come adrift - resoldered it, turned the power supply on and it worked GR8 for about ten minutes, when one of the AC capacitors on the input decided to set on fire. On top of that, it didn't actually fit inside the case on account of it being 10mm larger in all directions than specified.


So, my power supply ended up being an even more cheap universal laptop power supply (for now) along with a load of capacitance to beef it up. This has the advantage that it'll also work off a 12v feed, but I've never tested it. This was also ordered off chinese ebay a few months ago but none of the supplied tips fitted my laptop. I've already cracked it open and repaired it (it turned up completely DOA due to the voltage switch being full of gunk)

Anyway so here's the amp in all it's "glory":







It seems to work great - By ear, it seems to be more powerful than my Denon 55wpc amp , and with normal music the power supply can keep up, too (it only dips by about half a volt according to my cheapo scope) but I'll probably end up replacing it at some point. With a tone generator doing 40hz I can suck the supply dry after a couple of seconds. As for sound quality, I'm not good at articulating what I hear unless the SQ is particularly poor. I can comfortably listen to this amp at high volume all day, whereas many much more expensive systems have been tiring to listen to.

Ignore the solid core wire as the speaker outputs - I'm not some audiophile plonker who thinks it'll make a jot of difference, but I just thought it would be neater than using stranded flex, and I had some of it to hand.

The little fan on the amp seems a bit overkill, but it's totally silent when sealed in the ally case. It's a bit silly enclosing a fan in a sealed case, but the air circulates around inside and the whole thing stays fairly cool because the alu case is good and conducting heat.

So overall, other than the PSU setting on fire (the seller has already dispatched another one) everything arrived in under a fortnight and was just as described.

As for ebay chinese sellers, sureelectronics seem to be pretty good (I've used them dozens of times and never had an issue) so I can 100% recommend them. The case guy seemed good, and we'll see if the power supply guy sends a replacement like the promised. I'll just have to use the replacement 24v supply as a bench supply or whatever when it turns up.

[MiataMark]

Nice, like the case especially.

Mark

[g40jon]

really nice build! I will be interested to see how well it lasts (my experience of chinese ebays goods hasn't been good! I bought a couple of temp gauges to use on my cars to show outside air temp. the gauge itself worked fine, but the back-lighting failed after ten mins on the bench power supply at work. de-soldered the cheaper than chips surface mount leds and fitted some that we had kicking around at work and they have been fine since! The were cheap mind! £6 for 2 and exactly the same as the ones i've seen uk ebay sellers getting £20 upwards for when described as boost temperature gauges!)

[Mark]

I used hifimediy for my TK2050 build after reading a fair amount of negative things about sure electronics so glad to see you had a good experience.

[Thrasher]

Brilliant, I ordered my TK2050 and control from sure and its all turned up no probs, struggling with which case to use ATM.

Need to wire up the volume control too. :-)

[cobblers]

If you've got the exact same amp as me there's a 5v output to power the volume control board, and you just run the signal and ground into the volume board, then out to the amp itself. If not you need to get a 5v supply from somewhere, there's bound to be one on the amp as it'll be used for logic for the TK2050

Then I had some problems with the wire that connects the volume knob to the actual control board - two wires were included, one did nothing, one one worked one way round - the controller has a couple of modes for use "standalone" or for use with some certain amps, and I think you choose the wire you need to select that mode - it's not very well explained in the instructions.

It's got a mode where you press the volume knob and it can go into a "menu" for use with more advanced amps. For some reason it comes on in this mode by default so you have to click it before it works.

[Thrasher]

Thanks matey,

does yours look like this at the input end ?

[mym]

how hard would it be to adapt one of these to work in a car environment?

[cobblers]

Nov 26, 2012 19:22:12 GMT Thrasher said:

Thanks matey,

does yours look like this at the input end ?

It did til I desoldered the phono input jacks.


Connect the bottom 4 holes at the top marked CH2, GND GND CH1 to the corresponding outputs of the volume control board. Around the edge of the board (left side IIRC) where there's space for screw terminals should be a pair of pads marked as supplying +5v and gnd - that's the power supply for the volume control board.

Tie both the grounds of your input phonos together and run that into GND on the volume board, and the signals to CH1 and CH2 on the volume board respectively. It "should" work, if you get no sound just connect a bit of wire shorting the input and output of the volume control board together to see if you get sound then, if not then the amp isn't working properly for whatever reason.

Nov 30, 2012 8:51:50 GMT mym said:

how hard would it be to adapt one of these to work in a car environment?

I was looking at this the other day. The amp itself should run straight off 12v, just at a much reduced power (In the region of 25w per channel)

If you want to get anything approaching the 100w per channel you need a ~12v to 32v boost converter that'll do about 8A to 10A on the output. There's modules on eBay about that can do that for about £30 or so. Then you need to put the whole thing in a case, add a few capacitors, terminals and some soft start circuitry off the remote lead to stop the power supply tripping off when it tries to dump 35v into the capacitors.

[jaykay]

just a quick thought dude. is there kit availible to make a half decent cd player home brew? i have a cyrus one, and i want to make a half case cd player to match it...