[Dimu]

   
More updates from Elekit.
 
The limit is a combination of the output capacity of the transformer and the rectifier in the pre tube heater circuit. They suggested using a rectifier with approximately 2x capacity of the expected current draw for the heaters. I ordered a 1000v/2A rectifier to drop in but if that runs too hot I will go up to a 3A, which will require a bit more work to fit as the package size is completely different. As long as the rectifier is upgraded, it should be fine to run the 12BH7 with lower-draw power tubes to keep the total load on the 6v secondary < 4A.
 
I've also reached out for a couple of quotes on a custom transformer to replace the one that came with the kit, with the 6v secondary winding supporting 4.5A.
 
    -Mike

 
Have you ever figured out a replacement transformer to drive more current to both the signal and power heaters at the same time?

 

[SuperDuke]

Got my hands on the ZMF Blackwood Headphone.  The TU8200 really wakes them up.  I'd say transformative is the right word.  

 

[thebigcanman]

With about 6 hours of listening time now I have to say I think the TU-8200 and HD800 will be a long term pairing for me. It is just fantastic. I have to say I don't really understand some of the characterizations of the HD800 I've seen online. I've seen people say it's like a pencil to the eardrum or that 1/3 of their music is unlistenable. I haven't heard a single "unlistenable" song through this. Yes, if a song is poorly recorded or mastered it is very apparent but that is much different. The real proof is that my fiancé gave a thumbs up after listening to a playlist I made her.

First aside: has anyone come across a compiled list of all the tubes that will roll in?

Second aside: over at diyaudio there is an Elekit sub forum and victor has posted a lot of good pictures, including more of the possible upgrade transformer. Still very intrigued by that.

Evan99, I'm also using the 8200 with HD800. 
 
I'm in ultra linear with KT88tube, but i want to move to triode with EL-34. What tubes/mode are you using with the 8200?

 

[430011]

Evan99, I'm also using the 8200 with HD800. 

I'm in ultra linear with KT88tube, but i want to move to triode with EL-34. What tubes/mode are you using with the 8200?

Right now I only have new production Mullard KT88 and Electro Harmonix EL34. I have found that I dislike the KT88 in ultra linear where the sound just didn't feel alive, but love them in triode. Then for EL34 I prefer to use the amp in ultra linear as I find the bass is a bit light in triode. They still sound nice, but swapping between KT88 and EL34 in triode will make the difference in bass apparent. I've never tried pentode.

I've been cruising different tube sellers to see where I may experiment some. NOS is outside my budget/I'm wary of getting a defunct tube. I think I'd like to try the new production Gold Lion KT77.

Beyond that I'm very intrigued by the possibility of a set of larger output transformers for improved bass.

 

[Dimu]

I've been cruising different tube sellers to see where I may experiment some. NOS is outside my budget/I'm wary of getting a defunct tube. I think I'd like to try the new production Gold Lion KT77.

 
There are good NOS dealers who do extensive testing and who will accept returns should you be not satisfied. I would not worry about defunct tubes. Just buy at the right place and communicate your expectations clearly.
 
As for budget it stretches from around $125 plus-minus $15 for matched pair of 6L6GC GE or Sylvania (both good tube choices) to north of $300 for short bottle RCA 6L6GC (sounds better than GE and Sylvania) to $400 and more for tall bottle RCA and European tubes like KT66. If you have never heard RCA or those European tubes you won't know that you are missing anything with either GE or Sylvania, and those are clearly better than modern tubes (especially if you subscribe to the concept that NOS tubes last longer than modern tubes, in which case GE or Sylvania price becomes very easy to justify).
 
EL34 can be had reasonably priced too if you don't insist on original Mullards. For example RFT EL34 are fairly cheap in Europe- about half the price of Mullards. Genuine NOS KT88 are almost non existent unfortunately.
 
Another way to improve sound with NOS tubes without major budget is to get NOS driver tubes- you will notice good difference relative to stock driver tubes. There are some good reasonably priced options out there and these tubes last a long time. Having said that I have to admit the more expensive driver tubes do sound even better (think Telefunken for example).
 
You will always be able to "try new production". But trying those NOS tubes will be increasing difficult as time goes on.

 

[SuperDuke]

I have the Mullard Reissue EL 34s and could not be happier. Not sure what the XF2 designation is but I think someone on this thread steered me in that direction.  
 
http://www.ebay.com/itm/290680925976?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[JK-47]

Wow, tube prices have really sky rocketed in the last year. I was paying $60 a matched pair for GE 6L6GC's not long ago. Crazy !!!

 

[Dimu]

  Wow, tube prices have really sky rocketed in the last year. I was paying $60 a matched pair for GE 6L6GC's not long ago. Crazy !!!

 
If you want unused tubes then yes, NOS power tubes are on their way to extinction and prices are going to continue to reflect that. 350B and KT88 are gone, GEC KT66 are almost gone, Mullard EL34 and RCA 6L6GC are going to be next to disappear, and eventually you'll see GE pairs for $500. 
 
Also there are different GE vintages. Those from 1960s cost more than 1980s production. And I have an impression that GE tubes from 1960 sound better too.

 

[tdogzthmn]

Anyone have experience with this amp driving 600 headphones? I have an AKG K240DF and K400 (120ohm). Both are great headphones and I would hope the 8200 would serve them well.

 

[JK-47]

I have several tube testers, and have found even tubes advertised as NOS, are not. Just because the seller claims NOS, NEW, etc, doesn't mean they are, new crisp boxes do not guarantee a new tube. I've had "closely matched", "NOS", "unused", "not micrphonic" tubes from poplular sellers that were not as advertised when I tested them. The difference between the reputable dealers and the unscroupulous ones are, the good ones will refund /exchange with little fanfare. The bad ones will fight tooth and nail to avoid doing thre right thing.

 

[JK-47]

Anyone have experience with this amp driving 600 headphones? I have an AKG K240DF and K400 (120ohm). Both are great headphones and I would hope the 8200 would serve them well.

What are 600 headphones?

 

[tdogzthmn]

 
What are 600 headphones?

 
Meant to say 600 ohm headphones.  
 
I'd like to know if the amp works well with higher impedance headphones.  I now see some posts mentioning good results with 300 ohm sennheisers so I would guess they can drive 600 ohm cans to high levels as well.

 

[JK-47]

   
Meant to say 600 ohm headphones.  
 
I'd like to know if the amp works well with higher impedance headphones.  I now see some posts mentioning good results with 300 ohm sennheisers so I would guess they can drive 600 ohm cans to high levels as well.

 
Thanks for clarification, I wasn't sure if you were refering to the Sennheiser HD6x0 series or 600ohms. Works fantastic with the 300ohm Senns

 

[Dimu]

   
Have you ever figured out a replacement transformer to drive more current to both the signal and power heaters at the same time?

 
Would be interesting to hear whether replacement transformer worked out for Mike?
 
I've got confirmation from Elekit that PCB conductors can handle double heater current for V1 and V2 tubes. So after upgrading the rectifier 600ma tubes can be used with 6L6GC and KT66, however using them with  EL34, KT88, 350B, or any other 1.5A+ tubes requires transformer upgrade. I think I am also going to add a fuse to the 6V transformer output.

 

[mhamel]

   
Would be interesting to hear whether replacement transformer worked out for Mike?
 
I've got confirmation from Elekit that PCB conductors can handle double heater current for V1 and V2 tubes. So after upgrading the rectifier 600ma tubes can be used with 6L6GC and KT66, however using them with  EL34, KT88, 350B, or any other 1.5A+ tubes requires transformer upgrade. I think I am also going to add a fuse to the 6V transformer output.

 
I did have a custom transformer made but it does not fit the existing space. It's on my project "to do" list to add an external case/umbilical for it.  I had reached out to several places, but didn't have much luck with responses. I ended up finding a guy over on diyaudio that custom made it for me.
 
That's a good idea on the 6v output.