FWIW, I have been checking back to the YJ frequently, and the statement: "Adjustable Frequency Crossover 70Hz~150Hz " was not there last time I checked. So who knows? Xrk971, please let us know if you hear back.http://www.diyaudio.com/forums/members/xrk971.html
Well, as the Chinese New Year is almost here, I wonder whether YJ has closed for holidays.
Regards,
Hmmm, interesting. I thought all the Chinese boards are essentially the same circuit - the one described in the data sheet/application note. The main differences between them would be the PCB design and the parts used. Look like Saturnus is right, the PCB of this green board is better designed than the YJ board?
Now, I am tempted to get one of this green board.
Regards,
green or red? pbtl?
This green board is not the same one which has the previous one shown which has the pbtl or mono capability. I am about to take the plunge on one of these designs, which one sounds the best stock and easiest to modify if i decide to? My soldering abilities are to the best..but could improve quickly! Thanks for any suggestions!
This green board is not the same one which has the previous one shown which has the pbtl or mono capability. I am about to take the plunge on one of these designs, which one sounds the best stock and easiest to modify if i decide to? My soldering abilities are to the best..but could improve quickly! Thanks for any suggestions!
I actually thought Saturnus said this design was not optimal because it did not use the tightest layout and the caps were not ceramic SMT. I may have misread it. It is a compact package and skips the volume pot which is a plus. I am concerned that the gain setting appears to be 36 dB vs 24 dB as on the YJ boards. This may make for a lower input impedance?
The output caps are tantalum. Next best thing. The board layout isn't optimal but by a good margin better than the YJ boards, and a mile better than the breeze amp.
I must also stress that just being SMT X7R ceramic caps in the output filter section is not in itself a good thing, they must also be rated for at least 100V, and preferably 250V, otherwise tantalum is preferable. An alternative to a 250V X7R caps could also be 2 100V X7R in parallel, one being 676 times smaller than the main cap, and main cap value could be 1.414 times larger than nominal for best effect (keep the 676 times ratio).
I must also stress that just being SMT X7R ceramic caps in the output filter section is not in itself a good thing, they must also be rated for at least 100V, and preferably 250V, otherwise tantalum is preferable. An alternative to a 250V X7R caps could also be 2 100V X7R in parallel, one being 676 times smaller than the main cap, and main cap value could be 1.414 times larger than nominal for best effect (keep the 676 times ratio).
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Yes, Saturnus is right. I think the circuit is sligthy different, with mute function and other gimmicks, probably some smd caps to act as filters on the powerline. Not sure, but it looks like that to me. But the core circuit for chip operation most likely follows the datasheet.
At the moment I have not tested it. I guess it has to do with the mute function working as a "stand by". But with the chinese instructions I am not sure how to make it work, though the pins are labeled as GND, MUTE and SD.
Not, it's not the same. The PBTL/Mono sells on Ebay only, and these retail on Aliexpress/Taobao.
If these are similar to Tripath boards, the most crucial components are the input capacitors, followed by output filter components (coils and caps) and then power capacitors.
One thing I forgot to mention, the power caps on this board are rated 35V. And a gain switch would be great.
For 15 bucks it's worth the try. I have a few of the blue boards (taobao only) on the way, might be better, but no ideia when they arrive.
Great... hope to read you comments on blue one soon! I'd like to buy one of the green or blue board.
How does "mute" work? Does it need just a switch?
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This one is interesting as it is the first to use the factory spec 10 uH inductors instead of the 22uH ones on all the other ones. Also, it has polyester film input cap instead of ceramic SMT cap and has tantalum filter caps coupled with polyester film caps for RF snubber. Also the first one to have what appears to be a zener diode - presumably to set a voltage for the no sonic boom (turn on thump suppression) switch. The price is unbeatable. Curious to see how this one works out.
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I found the green PBTL board here ??? 50W+50W?/100W - , I am looking into getting a shipping service, at $8.60 I would be a lot more likely to try a couple than the $29 on Ebay
xrk
Thank you for pointing it out. I did not realised that the gain is at the maximum setting. I am a little worry about possible noise issue. Something around 30 db is the maximum that I prefer. Well, I guess the YJ and this green board is not quite the same then.
Regards,
On the gain setting. Think of it this way. Gain has to match the source.
20dB gain match balanced or automotive high voltage line level signals
26dB gain match normal line level signals
32dB gain match portable equipment headphone output
36dB gain match very low output devices like some ipods and smart phones headphone output
20dB gain match balanced or automotive high voltage line level signals
26dB gain match normal line level signals
32dB gain match portable equipment headphone output
36dB gain match very low output devices like some ipods and smart phones headphone output
I might have to swap out the tiny SMT resistors to set it to 26dB if needed. Although I will listen to it first at 36dB to see what it sounds like. Although my miniDSP is having a hard time driving my current 24dB gain to high volumes so maybe this won't be so bad.