845 DHT SET electrostatic headphone amp (scam alert)

Can you share where you got the switches from? I know they are pretty standard in the hobby community, so why not know which one is the "best".

Thank you for sharing your awesome builds!!

 

It occurs to me... are modern tubes all made by machine or is there any hand assembly involved?

 

That's one heck of an aesthetic, totally stunning and quite unique, thank you for sharing your work with us here! Are your designs up for sale at all?

 

Even at the height of tube manufacturing there was still a bit of hand assembly required to line up the metal components.

 

I'm guessing KR tubes are maybe more hands-on assembly than stuff like Shuguang or New Sensor stuff, and the video doesn't cover things like plating the filaments with special sauce, or stamping and coating the plates, or forming the mica, but it should be evident that it's a relatively manual process.

 

No hum I've experienced, dead quiet at even maximum volume. Actually I'm really surprised about Kevin's designs, none of the amps experienced this, even sometimes the power transformers are really close to amp boards.

Depending on the materials of the cores. The Amorphous cores are from Japan and Finemet are from India. Insulation paper is teflon. Here is a pair of output transformers for the 45 tubes that I've just made a week ago. Notice the grey-ish cores, they are Amorphous. Other cores are often black or darker grey.

 

It's from a firm in China. Believe it or not, everything is not made the same in China. There are still some very high quality stuffs made for domestic use there. I bought those switches from like 5 different vendors and found this is the best. The switches out there may look the same but build quality and press feeling are totally different. They also have a high current (13A) version which I used in the T2.

 

Thanks, those are all thanks to the generosity of Kevin Gilmore. I just tried to put his fantastic designs into pretty boxes. Yes, some of them are for sale when I need to fund for other builds.

 

I got some weekend time to work on the new project, the revised T2.

I decided to go all-in and opted for all 1W resistors with at least 5mm rise above the boards. This ensures maximum airflow and preventing high voltage shorting to the groundplane which I experienced in the past. If this turns out to be a successful build, next time I'll have the heatsinks machined from a single block of aluminum, like what Boulder do.

 

@Beefy wipes a tear from his eye

It's beautiful!

 

Weekend, so next to the power supply. 2 separate transformers, a 80W one for the low voltage stuffs and 300W for high voltage rails. The T2 does require a boatload of supplies. All 14 wires to a single gigantic umbilical jack which takes up most of the height of the rear panel. I try to organize the wires as tidy as possible, did take quite a lot of time but I'm happy with the result.

 

I'm somehow imagining that you can get very cheap custom enclosures in Vietnam.

 

It could be cheaper but “very cheaper” a wrong idea. 3 main suppliers of aluminum (China, Korea and Switzerland) have increased their prices significantly after the Covid19. Cheaper for me because I do the design and machining on my own, not sure the real cost if I hire a firm to do. I do wish I could buy cars as cheap as in Europe or the US though, $45k only gets me a bog standard Camry with lots of features removed.

 

Do not suggest dealing with the topic starter.

I bought CFA3 build from him this summer. The visuals are beautiful, I liked the housing. But, it was dead on arrival. I sent a mail to him about a problem and did not get any response.
Thankfully, I have a friend who can do a repair, so I took it to him. The basic problem was not terrible, just one solder joint come loose. It was quickly fixed.

Then I come home, listen to it for about two hours, and right output transistor burns. So back to repairing.
We also found that power transistors at the dead channel were completely different, looked like they were the same initially, but then some burned and he installed another type. They did not fit well but were roughly soldered in anyway. So I ordered new transistors, we matched and put them in place.
After this, for about half a year it worked fine, until yesterday. Now left channel is burned out. I'm not sure what the exact problem is right now, but I asked for help in CFA thread on head-fi, and, well, quote:

https://www.head-fi.org/threads/kg-cfa3-headphone-amp.938064/post-16730444

I started searching, and come around this head-case tear-down of another Felitsa work: https://www.head-case.org/forums/to...hone-amplifier/?do=findComment&comment=863358
You can read after that, KG himself is basically rebuilding that amp right now from scratch.
Seems, my amp is beyond saving as well:
https://www.head-fi.org/threads/kg-cfa3-headphone-amp.938064/post-16732331

And it isn't a full list of problems, there are much more concerns told to me by Dukei in head-fi pm.

So, basically, I bought pretty housing for $3000. And it is the most costly piece of audio gear I ever bought, even slightly more than my speakers, which has a sad story associated with them as well. Both of my most costly audio purchases are a complete disappointment

 

This is why I stick with Mid Fi. Low expectations, low disappointment.

Really sorry to hear about your experience. I had seen that the Felitsa electrostatic gear was terrible on Head Case, but the solid state stuff I'd seen posted looked reasonably good. I guess the glamor shots didn't show up the problems.

Suffice to say, I now wouldn't touch that T2 I liked above with a 10ft pole.

 

This maybe deserves more attention. @purr1n @ultrabike (sorry I wasn't sure which mod to ping.)

I know Head-Case can be overly critical, but OP also seems to have disappeared with a serious amount of money from community members (10 or 20K USD or something???) in build fees with nothing delivered under a different name quite a few years ago. Super shady. Not to mention the dead amps etc...

I almost bought a Dynahi from OP based on this thread. Glad I didn't end up going for it.

 

I'm sorry to hear that. I'm getting a CFA3 built by Dukei but it's good to know when a builder isn't honest. The pretty housing does look great but if it's built to fail, everyone should be aware of this issue if people are going to continue to give the builder money.

Have you reached out to see if fls will fix the issue? If he will, I'd suggest having someone else review the work as well.

 

If you follow the whole story back through the years, this person pops up every couple of years... new name, new aesthetic, new pool of people that they rip off.

Long and short of it, chances of getting them to fix it are zero. And even if they offered, chances of getting a properly built amp are zero, because they either don't know what they are doing or deliberately cheap out.

I'm rather embarrassed at myself that I didn't recognise them when I saw this thread. The T2 group buy going to hell was one of the last sagas I followed when I left the hobby years ago.

 

A summary from somebody with recent experience ( @ufospls2 , @Drakkard ) in the thread below would be helpful:

https://www.superbestaudiofriends.org/index.php?forums/buyer-and-seller-feedback-negative.68/