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Headphone Systems Everything to do with Headphones

E19 headphone amplifier board K2381 J407 MOSFET Yuanjing Audio
E19 headphone amplifier board K2381 J407 MOSFET Yuanjing Audio
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Old 5th September 2016, 05:54 PM   #11
nattawa is offline nattawa  Canada
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I set the output bias at about 60mA per transistor and be done with it

I wouldn't worry about the power filter capacitance. 4x 6,800uF is more than plentiful. In my C-R-C rail filter configuration that supplied with a 20VA 2x12Vac Antek toroidal, the 120Hz saw-tooth is about 120mV in amplitude on the first cap, and quarter that after 0.5-ohm on the second cap. I could go with a 10VA 2x 15Vac tranny for its much larger internal resistance if the ac hum was a challenge. For a Class A headphone amp where load regulation is not much of a concern, a smaller power rating transformer often widens the conducting angle and lowers the charge current peak, making a less noisy PSU.
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Old 5th September 2016, 06:43 PM   #12
HotIce is offline HotIce  United States
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Quote:
Originally Posted by nattawa View Post
My guess is they have failed that model of headphone amp and are dumping the batch of failed prototype builds to the online market, which in my book would be a malicious conduct.
Yes, exactly what I meant.
Many just grab either public schematics around, or reference ones out of manufacturer data sheets, which would work, if the devil within the detail would not play them tricks.
And the devil many times comes in the form of proper ground routing, or PCB signal routing in general, or properly designed power supply (which is mostly omitted by public or reference schematics), or/and choice of cheap/fake components.
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Old 5th September 2016, 07:29 PM   #13
keilau is offline keilau  United States
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Quote:
Originally Posted by HotIce View Post
Yes, exactly what I meant.
Many just grab either public schematics around, or reference ones out of manufacturer data sheets, which would work, if the devil within the detail would not play them tricks.
And the devil many times comes in the form of proper ground routing, or PCB signal routing in general, or properly designed power supply (which is mostly omitted by public or reference schematics), or/and choice of cheap/fake components.
That's why we need this forum here to sort out the pros and cons of many offers on Ebay or various websites. Nattawa did a wonderful job helping other users to make the E19 to work.

Among the FET input and full complimentary MOSFET output headphone amplifier boards, which is the one that meets your standard? Do you mind to share your experience too?
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Old 5th September 2016, 10:01 PM   #14
HotIce is offline HotIce  United States
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Last time I bought a "kit", it was many many years ago, wasn't on ebay/amazon/alibaba, and I don't even remember its specs.
Nowadays I either design them from the ground up (schematic, pcb, ... - for fun), or I buy directly brand ones.
The reality is, unless the design and/or implementation are really wrong, they will all have have flat-at-glass-tabletop frequency response within the audio bandwidth, and a distortion which is MUCH less than what the human ear can distinguish.
Given that, when I do design them, I like the challenge of achieving the "I can't tell the difference" result, with as much simplicity (in terms of design and number of components) as possible.

So, sorry but I can't suggest you any preferred ebay kit. Some sellers do follow up, and show up in forums like this one, but the reality is, out of a $30 kit, do you want to spend another $20 for shipping back to China (and wait at least a month of turnaround)?
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Old 6th September 2016, 02:03 AM   #15
keilau is offline keilau  United States
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HotIce, most of us participating here are hobbyists with various degree of understanding in electrical and electronic basics. Most are not well educated to do their own design. It may be true that yours is better than the rest of us. Find a way to contribute for the rest of mere mortals.

Nattawa showed how one can make lemonade out of a lemon, the E19.
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Old 6th September 2016, 02:25 AM   #16
HotIce is offline HotIce  United States
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Originally Posted by keilau View Post
HotIce, most of us participating here are hobbyists with various degree of understanding in electrical and electronic basics. Most are not well educated to do their own design. It may be true that yours is better than the rest of us. Find a way to contribute for the rest of mere mortals.
Where did I say, or even imply, that my design are better than "the rest of you"?
You asked for a suggestion for an ebay kit, and I told you I am sorry, but I prefer not to buy ebay kits, and hence have no experience to suggest one.
There are countless schematics on this site, with people sometimes offering PCBs.
If not, you can have PCBs made for cheap (using the posted Gerber files), and head to Digikey or Mouser to pick the various components.
Clearly, it is going to be more expensive than an ebay kit.
But if you consider the probability of getting a lemon by buying ebay kits, and you include that into the cost, that "more expensive" might suddenly look not so expensive after all.
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Old 6th September 2016, 05:42 PM   #17
phase is offline phase  United States
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I have the E5, has been a great amp.
This one wasn't around back when I purchased mine, am thinking this is a "copy".
There are other versions from the same seller as the E5 also, a progression in the design, E5 being the more recent.
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Old 6th September 2016, 06:26 PM   #18
keilau is offline keilau  United States
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Originally Posted by phase View Post
I have the E5, has been a great amp.
This one wasn't around back when I purchased mine, am thinking this is a "copy".
There are other versions from the same seller as the E5 also, a progression in the design, E5 being the more recent.
Yep, the E5 is a good board.

After I got the E19, I found this Audio Technica HA5000 clone board. I may build another box when I finish the E19 project.

Reference HA5000 MOSFET Class A Headphone amplifier AMP kit Toshiba 2SK370
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Old 6th September 2016, 07:44 PM   #19
ammel68 is offline ammel68  United States
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E19 headphone amplifier board K2381 J407 MOSFET Yuanjing Audio
Several different amps have been mentioned here.

Is the E5 as good or better than the E19?

Is the more expensive "Reference HA5000 amp" suppose to be better than the E5 and E19?

With all the hacking and reworking needed for the E19 board, I think I'm going to pass on it.
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Old 6th September 2016, 10:05 PM   #20
phase is offline phase  United States
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Don't know about the ha5000 board, looks fairly beefy, doesnt have a protection circuit however, and is dc coupled it appears.
The e5 doesn't have input protection, which is fine with me.
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