Reverse Engineering of a Chinese Tube Headphone Amp

[amirm]

I want one.

Write us a dozen technical articles Don and I will buy and send it to you for Christmas present.

 

[NorthSky]

MiniDSP UMIK-1 ($75+$20 s/h from HongKong) is a safe choice in my opinion, plug and play with REW software for measurement.

REW reads the calibration file and no further fiddling is needed for reasonably accurate performance.

Cross Spectrum Labs sells them (when they have them), maybe with a better calibration file.

I want one, black. It's my birthday tomorrow.

 

[mingkahn]

I want one, black. It's my birthday tomorrow.

happy birthday of good sound

 

[NorthSky]

Make it happens, make it counts ♪, buy me one.

 

[DonH56]

The DSO, though after watching the vid and looking a bit, the next higher line is pretty interesting.

The CSL-calibrated UMIK-1 is the mic I (and RayDunzl, and many others) suggest, along with REW. It is a blessing and a curse that it is comparable to my much more expensive previous setup using an Earthworks measurement mic, preamp, and professional analysis software (all of which I still have but rarely haul out). The UMIK-1 is not as quiet nor has the dynamic range of my Earthworks, and of course is nowhere near as intrinsically flat, but for routine measurements is an incredible value. The measured response using my M30 and the UMIK-1 practically overlie.

 

[DonH56]

Write us a dozen technical articles Don and I will buy and send it to you for Christmas present.

Gee, in front of witnesses and everything. Very tempting, if I ever get off the current work treadmill (26 days straight, finally have the weekend off). Not sure they are needed on this site, however, and a dozen sounds easy until you sit down to write them.

Wait, I could just copy over my WBF threads, hmmm...

 

[ceedee]

Not actually a tube amplifier. More like... We have buildings full of worthless tubes let's find something to do with them.

Used properly tubes can be wonderful devices, sad many know so little about them these days.

That's alright … I don't think the tube even has to be in the signal path for audiophiles to hear a difference!

 

[Don Hills]

That's alright … I don't think the tube even has to be in the signal path for audiophiles to hear a difference!

Check out the use of tubes in this example, another of David Jones' teardowns:

 

[amirm]

Yeh, I remember watching that. The scam can be a lot worse. Often you get boxes willed with bricks instead of any audio gear. I was actually approached by one when I lived in Florida. White van and all. The guy who chased me in the parking lot of the grocery store was quite aggressive and took the attitude of, "how can you pass up on that" in semi angry tone! The white van was full of sealed cardboard boxes.

 

[TBone]

"Hey buddy, want a great deal on ..."

White vans troll our local shopping parking lots looking for suckers all the time. For some reason, they always choose me (how they know I'm an audiophile is beyond me, perhaps they can smell it) strolling back to my vehicle. If the mood fits and I'm alone, I pretend interested. I always look for their biggest boxes, usually tight fitting speakers. Real pain for 'em to remove and repackage, but I insist seeing the product before any cash transfer. Love watching 'em struggle in the confines of a small van filled with big boxes. We talk shop until the speaker/object is removed, then I ask em to wait while I pretend to go back in mall to the bank machine for cash ...

 

[RayDunzl]

I might not troll anyone in person like that, we live in dangerous times...

Lemme get my brother...

Meanwhile, I'm stuck wondering how you "pretend to go back in the mall".

 

[TBone]

I might not troll anyone in person like that, we live in dangerous times

Yeah, location location location, open public area, distance & caution, plus mall security camera's are everywhere and these mugs are fully aware of their presence, they need keep moving to avoid mall security.

Meanwhile, I'm stuck wondering how you "pretend to go back in the mall".

simply walk away in that general direction, they generally know the gig is up by then, cursing away ...

You are indeed correct, it is a rather silly risk, not recommended, but I can't help myself, and honestly, I feel way more at risk (and for good reason) way up north in Gods country, but there I have Stewey.

 

[NorthSky]

Check out the use of tubes in this example, another of David Jones' teardowns:

Lol, he keeps the $4,ooo projector that he found @ the dump, and he destroyed the sub by poking it with a screwdriver real fast like if enraged.
Numero uno; I doubt that he found those two items @ the dump.
Numero dos; he is so biased that he just keep repeating himself...and that's all what she wrote, all that sort of jazz.
Numero tres; he is just too funny with that 7.1-channel Marc vincent stereo brand. But he likes Marantz.
Quatro; Too much, he should apply for a job in Hollywood.

 

[amirm]

Numero uno; I doubt that he found those two items @ the dump.

He does actually. He lives in an apartment complex with a centralized trash area. He has shown videos of it where he goes and finds everything from computers to TVs and such.

 

[NorthSky]

Amir, a $4,000 front projector! Wow, you have videos of him going through the trash where he lives?

When he destroyed that sub driver, it was like that he wanted to make sure that nobody else can have it when he trashed it himself in the dumpster.
A seven-year old kid would have loved to have a stereo in his bedroom. ...7.1-channel as a matter of fact, with three cool glowing tubes, and a welcoming front panel display.

Anyway, I'll send him an email, with this test: https://www.16personalities.com/free-personality-test

...and this video:

 

[amirm]

Wow, you have videos of him going through the trash where he lives?

Sure. This is one I found in a quick search: https://www.eevblog.com/2014/12/09/eevblog-691-dumpster-dive-xeon-servers/

 

[mingkahn]

Sure. This is one I found in a quick search: https://www.eevblog.com/2014/12/09/eevblog-691-dumpster-dive-xeon-servers/

good food in trash to

 

[NorthSky]

I checked few of his finds; he certainly is an expert trash electronic finder. He knows were to rent an apartment.

He even found three magnificent full aluminum cases that can be used to put his next multichannel power amplifiers...McIntosh hi-end style...wow!