Bought a XY LM3886 Kit.

I am kinda new to building amplifiers and HiFi equipment , buy have been working with electronics for a couple of years now, but build mostly sumo robots and other projects.
have ordered a xykit from eBay, and a speaker protection kit, but have some stupid questions
I am gonna drive a pair of dynovoice speakers. as computer speakers
Dynavoice Magic S-4 EX
to be more specific.

1, can I connect my PC directly to the gain clone without a DAC?
2, what is the best way to regulate the volume, and is there schematics, if its a build
3, is there any other module or PCB that is recommended for me to have in the amp
 
with all things made by xy one has to study the original data sheets then trace the xy board figure out what is missing or different or what size part does not fit on the space they provide so thus making it all the more challenging as to what you can build out of them i think the demand dropped off for them and maybe that brought down the prices as they themselves had realized that their boards had some limitations thus why you get version 5 printed on some boards which makes me think that 4 older versions had problems???
 
I am kinda new to building amplifiers and HiFi equipment , buy have been working with electronics for a couple of years now, but build mostly sumo robots and other projects.
have ordered a xykit from eBay, and a speaker protection kit, but have some stupid questions
I am gonna drive a pair of dynovoice speakers. as computer speakers
Dynavoice Magic S-4 EX
to be more specific.

1, can I connect my PC directly to the gain clone without a DAC?
2, what is the best way to regulate the volume, and is there schematics, if its a build
3, is there any other module or PCB that is recommended for me to have in the amp
I would almost never use opamp as first stage of gainclone.
For volume i would use potentiometer.
Dac might be needed if sound card is horrible.
 
The 2.2uF capacitor is the DC blocking capacitor as Andrew mentioned. This means that it prevents DC from entering the amp and destroying your speakers.

You can read about it on the My RefC thread where people have even bypassed it if the DC at output is very low or if your preamplifier already has a DC blocking output cap.

The higher the value of the input capacitor the lower the bass frequencies will cut off (high pass filter as told by Andrew). To explain in a simpler way with an arbitary example, say 1 mfd capacitor will pass frequency of over 40 Hz (so you lose the 20-40Hz band) while a 2.2 mfd one goes down to 20 Hz while a 10 mfd may gown down to 5Hz. Since healthy humans can hear from 20-20KHz, a 10 MFD will be an overkill (and enormous too). One can use from 1 microfarad and above however 2.2 to 4.7 will be the best.

After searching a lot of sites for a good yet small input cap I only found that the panasonic polypropylenes are the ones that fit.
The value of R3 feedback resistor determines the gain of the amplifier.

Polypropylenes are better than polyester ones. Try to find a 2.2 polypropylenes that fit. Wima MKP / FKPs are bigger however you may solder them from below. Here is my schematic and BOM:

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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.

I was looking for an updated component list for the XY3886 boards is this a good solution? :xfingers: Thanks.
 
No.
The RF input filter is missing.
The decoupling C3 & C4 must be changed from MKP, to ceramic x7r or similar.
C3 is in the wrong place on the sch.
C8 is too small.

The type and/or value of component is far more important than the manufacturer.
But the biggest problem is the semi ground plane that has Power Ground and Speaker Return and Zobel Return and NFB and Signal Return all sharing the same bouncing potential. The three left most ground symbols must all connect directly and must be separate from the eight right most ground symbols.
The PCB must be altered if it still incorporates the shared semi ground plane.
 
Here, some pictures including the new PSU with the four Cornell Dubilier 18000uF 50V caps, the new amps, the speakers and the two sources I'm using, iPod Mini and QLS QA350 WAV player. Also, the new Thiele R//L network with bigger inductors and resistors on a PCB board, as Corpius did it.

I know, I have to fix the wire mess, it looks terrible, but this is just for testing purposes. Now I have a very little hum if I get my ear really close to the tweeters, but with the first amps I had NO hum at all, that's why I haven't bothered fixing the mess. But I will eventually do. And yes, the left speaker has a stain on the front, but that's how I got them, I bought them used, but they sound great.

Pemo, I still have to take the picture of the back of the Thiele PCB, I didn't do it now because I have to disconnect it, I'll do it soon.

Woah those caps are $30 each? ( CGS183U050V3C - CORNELL DUBILIER - CAPACITOR ALUM ELEC 18000UF, 50V, +75, -10%, SCREW | Newark element14 Canada )

Will those actually make a noticeable difference? I bought these (since one of the caps that was shipped was damaged) UFW1H103MRD Nichicon | 493-3183-ND | DigiKey and considering 4 of them cost more than the XY board I thought that was expensive.....
 
The amplifier, i.e the PCB and it's components are likely to be about 10% of the completed Power Amplifier total cost.
The 18000uF (=18mF) is part of the PSU. That PSU will account for ~30% of the total cost.

did you read this?

I mostly picked my caps randomly, I assumed the ones shipped weren't good quality considering I couldn't find a datasheet and the price wasn't much. I just went on digikey and grabbed something that looked similar from a reputable manufacture - wasn't a whole lot of science in my decision.

But again, will those expensive caps make a audible difference in the sound? Would the quality of my speakers negate any benefit of going with a more expensive/better component?

I'm pretty new to audio stuff in general and I'm a bit weiry of some of the stuff I read. I understand that on paper it's better - but if I can't tell a difference I don't see the point.

I will be ordering another one of these XY kits and will use the caps it comes with and test if I notice a difference. I'll probably also try some of the mods from this thread and compare it against my 'stock' board.

I have blown my budget by quite a bit on my first amp (though probably not as much as I thought since I ordered multiples of lots of items)
 
Is'nt the magic of these amplfiers in the chip and the choice of loudspeakers rather than the changing of a few components?

That's an ongoing, never ending dispute/conversation. I'm of the opinion, and by my experience, that the choice of components supporting a chip can make huge differences. That however, is totally non dependent on the cost of those parts. In one case a $9 Audyn Plus input cap performs at 90% -95% of it's big brother the True Copper of same value costing ~ $35. In another a Mundorf AG power cap ($45) produces (allows) more and cleaner bass than it's generic equivalent. I try to read a lot of posts from folks who have installed items on their own builds to get some direction and value considerations. Still end up with a few pieces to put in the "I'll use that later" box.;)
 
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I often wonder why speakers are never included in the equation by you modders?
I have purchased several different assembled boards and connected them to a collection of non diy speakers ranging from small cheap to large and expensive.
All the amplifiers sound mediocre on Radio Shack full rangers and wonderful on large Tannoys. I cannot hear the difference between a tpa3123, tda7297, tda7294
I think I prefer the 7297, perhaps it's because the PS requirements are modest and I'm just amazed by the sound that comes from so few components.
 
I often wonder why speakers are never included in the equation by you modders?
I have purchased several different assembled boards and connected them to a collection of non diy speakers ranging from small cheap to large and expensive.
All the amplifiers sound mediocre on Radio Shack full rangers and wonderful on large Tannoys. I cannot hear the difference between a tpa3123, tda7297, tda7294
I think I prefer the 7297, perhaps it's because the PS requirements are modest and I'm just amazed by the sound that comes from so few components.
My theory is..

(1) there's likely a big difference in sound with any amp between the RS's and Tannoys. You probably have a little 'expectation bias' built-in. I think a great pair of speakers will always reveal an amp's and source shortcomings. I've also found the type/genre and recording of music will make a setup sound good or bad - depending.

(2) when you're modding and trying to determine what makes the most sonic impact on the sound you should probably keep your source constant, as well as your speakers. Rule #1 of scientific observation. That said, I'm not sure how much scientific observation goes on with DIY'ers. :) It's just too subjective of a process. Our 'expectation bias' is hard to ignore.

(3) although my ears are getting older... :( I have a hard time telling any difference with many of these small, monolithic based chip-amps too. I think they all generally sound pretty good for the low price point they represent. I just don't think their specs are that far off from each other, but alas I don't have the equipment to measure any of them either.

My current sweet spot a little farther up the amp module food chain, is the class D IRS2092 by LJM. To my ears - and using relatively very inexpensive speakers - these are very musical sounding amps. I love the emphasis on vocals and mids and the timbre of the highs. With a good, well-adjusted sub in the mix I'm sure the sound would be even more pleasing. :D I'm waiting on a another 2092 module from Cristi to explore any 'noticeable' sonic differences between the two.

Rick
 
Jumping a bit more on track... What is a good pot value for the 3886? (specific on this board since it's what I have) I bought a 10k one since the data sheet seemed to indicate that was the best value but it really didn't offer much choice in volume, it was either loud or kinda loud.
 
Are you sure you have your pot wired correctly ?? your volume should vary between silent and full blast ..... When your volume knob is at it"s lowest setting the signal gets shorted to ground so it should be totally silent so if the Volume is either "Loud or kinda loud" then it points to an incorrectly wired pot ....
 
Are you sure you have your pot wired correctly ?? your volume should vary between silent and full blast ..... When your volume knob is at it"s lowest setting the signal gets shorted to ground so it should be totally silent so if the Volume is either "Loud or kinda loud" then it points to an incorrectly wired pot ....

So 10k should be fine?

(it should be wired correctly - I used a pcb but maybe that is junk)

I'm a bit confused here though - when the pot is at 10k that should be the lowest volume, and when it's at 0ohms that should be the loudest volume right?

The pot is a alps blue... this one 10K, Blue Velvet - STEREO
 
That pot is a fine pot , much better quality than anything I would ever buy and 10k is a good value to use .....

I bought several of those XY LM3886 boards off of ebay quite a while ago , They were only $2.50 each so I bought a few and am using a 10k pot with them and they work fine and as a volume knob should ....
 
Hi everyone, I'm back on this usefull topic beacuse I've just bought a pair of XY poweamp boards.

I would like to ask if would be possible to bridge XY boards...

I'm looking to build a mono guitar amplifier for 8 ohm speakers, is it possible with those boards?

thank you in advance... and sorry for my "dirty" english" ;)