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Megatron Electrostatic Headphone Amplifier


kevin gilmore
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Just wonder, what do you think about the build quality of the casing in this unit?

 

Not exactly related to this unit, but it seems that the builder is going Mikhail after this Megatron scandal surfaced. I sent my down payment for a CFA amp right before the issue about this amp appeared in this thread. Mainly I am interested in the casing of his amplifiers. They look good for DIY units.
I got a feeling that it’s not going to end well, but back then Thuan still communicates regularly so I got some hope. Until last month when he stopped giving updates and answering email..

Well. 

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Posted (edited)

this is a put together chassis of a specific size. where he bought the chassis i do not know, but it completely comes apart, all 4 sides, the round corner pieces etc. Then he had the front,back and top all machined. all panels are .2 inch thick. And the front wood piece is esentially a stick on made of unknown wood.

absolutely every single thing about this is fucked to the max. broke the anti-spin pin off the pot and did not even bother to drill a single hole to prevent the pot from spinning. Some of the work was definitely done by an nc mill, and a really shitty one at that. on the mill i used, everything was accurate to .00001 inch, and it really was at least this accurate. this thing is barely accurate to .008 inch. nothing on either inch or metric boundaries. and the holes for the power supply board were drilled by hand, and blind tapped, 2 of the 4 holes went all the way thru the panel.

But the worst is the way under-rated power transformers which were potted with definitely the wrong stuff. And wiring all the filaments together. 

And the stax jack it turns out is also massively fucked. And force held in with rubber o-rings. Gold plated hex screws with the gold coming off.

And the tube sockets were really low quality garbage, as bad as the russian crap that mikhail used.

The 3 boards from jlcpcb were a total of $65 with shipping. and shipping was half the price. The hand dremel tooled boards were so utterly fucked, no reason for any of this.

Somebody really high on really bad drugs did this. Not even mikhail or mike bean (hennyo) could do something so utterly and completely fucked. Wow, i gave hennyo a compliment, yikes.

The 300v tube supply is actually pretty clever and kind of unique, but also utterly fucked because he had the pass tube cathode wired to ground when it had to be connected to 300v.

And the bias supply with a 100k series resistor. Guaranteed to kill your headphones.

Its not my money going into this, so i will continue till its either completely finished and working or the tube diode power supply cannot be made to work. Looks like the repair price will be about $1500 in parts, plus the original purchase price of about $5k. All the improvements to the amp board are in the new board. There are places for solid state diodes on the power supply just in case.

There is no reason for any of this.

So far i have about 30 hours of labor in this. The mikhail es1 ended up about 50 hours of labor.

Yes i'm fucking nuts.

all you have to do is take my board files, have them made, stuff with parts, slap into chassis. how fucking hard can it be.

Edited by kevin gilmore
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Posted (edited)

So more than 30 minutes to disassemble the front panel, 10 minutes to get it aligned into my emco fb5, and 10 seconds to put in a fucking hole that should have been there from the start.

Notice the fucked up stax jack and the shitty finishing on the wood.

DSC_0912.JPG

Edited by kevin gilmore
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I believe this is the chassis used: 4308 rounded corners Full aluminum DAC chassis tubpower amplifier enclosure box | eBay

I believe Kevin has also managed to salvage the following parts from the original build:

1. Aluminum knob (1pcs 50x27mm Gold Aluminum audio Knob Volume Control potentiometer | eBay)

2. Strip of unknown wood

3. Power switch

4. IEC inlet

5. 4x feet

The total salvageable value of the parts was certainly under $150.  The cheap Chinese tubes included were certainly worth under $100.

Hence, the total as-delivered value of Thuan's amp was roughly -$8,600 CAD, or about -$6,000 USD at the time, -$5,000 USD for the amp itself, plus the cost of shipping, currency exchange, and a customs nightmare.

Pretending that Kevin or anyone else would actually be crazy enough to charge a modest $150 an hour for their time to work through to completion on completely re-designing and re-building something so hellishly nightmarish, the cost of the estimated 50 hour repair and parts would come to: $9000 USD.  Adding this to the acquisition cost would bring the total repaired cost to $15,000 USD.

I doubt anyone else could actually be both qualified and convinced to work on it in the first place.

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@tumpux

Thuan is alive, actively selling, and not in a medically-induced coma this time around, either; he just sold a supposed Dynahai under fls.audio, yesterday: REFERENCE DYNAHI Super Symmetry Dual-Mono Fully Differential Headphone Amplifier | eBay

I feel awful for all the people ripped off by this guy since circa 2009; why anyone in their right mind would post pictures of themselves, their sales receipts, shipping labels with US and VT addresses to flickr and leave them up for 12 years is simply beyond me... tee8tee4388 | Flickr

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On 8/29/2021 at 5:15 PM, orientexpedite said:

I apologize in advance if this is news to absolutely no-one, but after reading the entire DIY T2 build thread in anticipation of receiving my build from George, I was surprised to find a name and handle that looked familiar: Tran, and Lil Knight.

A search showed that the schematics of the failed DIY T2 board/case buy were posted in 2013 by a fellow going by Lil Knight under blogspot account tee8tee84388…  to my eyes, that rather unique Blogspot/Reddit/Flickr handle looks very familiar:

Yes, this is the same Tran who later sold the DIY T2 parts kits on head-fi as kytuphicanh, which also happens to be the selfsame Tran that built my ‘Megatron’, stamped FLS Felitsa Audio.  That incomplete sale, along with Paramesh’s, outlined earlier, resulted in kytuphicanh being banned (and mostly scrubbed, likely due to dozens of historical classified sales) on head-fi, and a warning placed under his alter ego, tranhieu.

Tran is tee8tee4388 on reddit, tranhieu and kytuphicanh on head-fi, and fls.audio on sbaf and ebay…  and we now know that you can presently message him as thuytn right here on head-case, since he so generously reached out, asking me to shut up about my dead ‘Megatron’, because it would ‘heavily affect his future sales’.

Tran, aka Lil Knight, aka tee8tee4388 on blogspot, takes credit for posting his failed DIY T2 board buy schematics here (Posted by Lil Knight, 12:21am, Wednesday, July 31, 2013):

http://tee8tee4388.blogspot.com/2013/07/t2-diy.html

Tran aka tee8tee4388 takes credit for my rather ‘unique’ (and dead) Megatron on reddit:

Fls.audio aka tee8tee4388 aka Lil Knight aka Tran takes credit for my Megatron build here on SBAF: https://www.superbestaudiofriends.org/index.php?threads/845-dht-set-electrostatic-headphone-amp.8740/

And Thuan Tran aka Lil Knight here shows off his Stax circa 2009, shipping labels and invoices on Flickr under the same tee8tee4388 user name, as he himself references in the below Reddit post:

https://www.reddit.com/r/headphones/comments/a2dsoo/was_randomly_skimming_through_an_old_flickr/

https://www.flickr.com/photos/[email protected]/page2

https://www.flickr.com/photos/[email protected]/page4

This particular Tran quote on Reddit, as above, caught my eye (regarding Singlepower):They stole lots of people’s money by not delivering amps. That sucks because their amps sounded very good, much better than the stuffs by Woo now.”

Indeed, that ‘sucks’.  How long was Singlepower around for?  Who has filled the void?

Tran’s ‘Megatron’ as sold to me omits all CCS loads, contains no inrush current limiting of any kind, has severely underrated power supply capacitors, a failed transformer/winding, and can hardly be called a ‘Megatron’ in the first place.

Fls Audio ‘creations’ still sell today on Ebay.  Buyer beware.  You now know who you’re buying from.

@gepardcv Yes, its the same Thuan, under 10 different characters and names, as quoted above; he made the mistake of replying to me under several different accounts over the past 2 years. 

I didn't fully put the pieces together until I read the complete DIY T2 build thread, in anticipation of receiving GeorgeP's build to replace his horrific amp.

Thanks to Kevin fully gutting the Thuan fls.audio nightmare, it looks like I'll have two amps!

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actually that plaque was a structural element that held the 300v board in. You can see the extra mounting holes on the new circuit board. But its way more than stiff enough without the extra 4 holes, so it can be flipped and re-engraved if necessary, but the screws won't be countersunk unless its re-machined. sounds like too much work for what is going to be a joke. birgir probably knows what i'm gonna do, but he better not tell.

notice that all the 9 pin tubes do not have countersunk mounting holes. Also way to hard to fix.

Edited by kevin gilmore
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On 4/4/2021 at 11:14 PM, jamesmking said:

My megaslow build.

Thank you JoaMat for supplying the 3 mosfets I needed for the golden reference psu.

The megatron is workingish. This build was a little perplexing. I used groove tube 12ax7, electroharmonix 12au7 (gold pin) and groove tube el34s.

_MG_6205.jpg

_MG_6204.thumb.jpg.ce5eee1bd02887af3f1af711cc9170f3.jpg

 

I implemented the 12ax7 increased current modification form the outset.

I found that I could only get about 220Vrms output before clipping. The clipping was not symmetrical and it was the bottom of the wave on the +O that was clipping only. I started to probe with a scope and found that the voltage drop at the 330K anode resistors on the 12ax7 was only about 19V on the +O side and about 35V on the -O side. Everything else looked fine. I scoped the output of the 12au7 when the amp was fine - no clipping when the output of the amp clipped. I checked all the psu voltages - no problems. It was the output of the 12ax7 was asymmetrically clipping.

I took the valves out and measured them and the 12ax7 was only managing about 0.5mA output on one plate and about 0.8mA on the other. The avo manual said I should be expecting about 1.2mA. I was not sure if the amp had damaged the valve or if the valve was weak. So I checked the amp and removed the extra current modification and tried with a stronger 12ax7. Now both the +O and -O clip at approximately the same point but the clipping is still asymmetrical. I'm getting about 35V to 40V across the 330K anode resistors on the 12ax7. The bottom of both outputs clips before the top, and I am getting about 440Vrms output before clipping.

I got in an email conversation with watford valves and the proprietor said that almost all new production 12ax7s are only capable of about 0.8mA and that only new old stock could do 1.2mA. So the high current mod might not be an option if you are running new production 12ax7s.

I did some frequency response measurements and found the -3db point was only at about 23-24Khz... which seems rather low.

Could someone tell me what output voltage rms they are getting before clipping and the -3db point for verification.

thanks in advance James

 

From above picture it looks like there are 12ax7 anode current sources and 330K anode resistors. You shouldn’t have both, should you?

Edited by JoaMat
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1 hour ago, JoaMat said:

 

From above picture it looks like there are 12ax7 anode current sources and 330K anode resistors. You shouldn’t have both, should you?

well I did think this was a bit strange. I have not really had time to experiment with the amp. The original pdf of the schematic only shows the 12ax7 anode connected to the collector of the stn9360 with a 150K resistor from the base to ground.

The gerbers have two 150K resistors in series from the base to ground and 330K 12ax7 anode resistors from the 300V rail.  (items in pink not in the original pdf schematic but present in the gerbers)

megatron.jpg.6b4c79a50aaf0b502f04fe3cbfedd661.jpg

 

 

Edited by jamesmking
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This seems to be where most of Thuan's fls.audio recent sales are coming from...

fls.audio | Super Best Audio Friends

Felitsa Audio (fls-audio.blogspot.com)

Anyone know Marv of SBAF to give him a heads-up?

@rayofsi Any chance you could provide some hi res shots of your fls.audio CFA-3 build?  And also possibly of your fls.audio Carbon: "I also have one of his KGSSHV Carbon builds he sold on ebay. It does some crazy inrush that my lights in my room dim a second when it turns on, but works well otherwise."

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17 hours ago, orientexpedite said:

This seems to be where most of Thuan's fls.audio recent sales are coming from...

fls.audio | Super Best Audio Friends

Felitsa Audio (fls-audio.blogspot.com)

Anyone know Marv of SBAF to give him a heads-up?

@rayofsi Any chance you could provide some hi res shots of your fls.audio CFA-3 build?  And also possibly of your fls.audio Carbon: "I also have one of his KGSSHV Carbon builds he sold on ebay. It does some crazy inrush that my lights in my room dim a second when it turns on, but works well otherwise."

Hey, emailed you back, Will get some pics. I also have a SUSY Dynahi that Thuan Sold.

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