ELEKIT TU-8200R

Hello All,

I finally finished building my TU-8200R kit with no issues and it sounded really good to my ears even with only few hours burn in with the stock JJ's tubes this amp have no problem driving a cheap bookshelf Pioneer SP-BS21-LR 6 ohms 87db sensitivity speakers. Next is to upgrade the coupling caps and will try different power tubes like KT88-ST is there anyone out here know about this brand Sophia Electric I read good thing about there tubes on some other websites. See linky Sophia Electric Coke-bottle KT88-ST Tubes (long life version). Any advice on other power tubes that is good for this kit? Your comments is greatly appreciated.
 
When I'm listening for 15 mins the enclosure gets a little bit hot around the tubes. I measured it with Laser Infrared Thermometer Temperature Gun and the temp register closed to 160F. I'm concerned that the components inside like the FET transistors will be able to handle this heat and is this normal? and also is this will have changes in sound when its get this hot? Your comments is greatly appreciated.
 
I checked the voltage on A1266 11,12 (1.13v) within ref. specs and 13,14 (-25v) 1 volt higher. On 23,24 (284v) 4 volts higher than the reference voltage. the rest of reference voltage are all in specs per manual. However I swapped JJ's 6L6GC to KT88's power tubes I'm not sure if thats the cause of my heat issue around the enclosure.
 
Just wanna show photos of my completed Elekit TU-8200R kit build and my listening experienced. I swapped power tubes to Sophia Electric Coke-bottle KT88-ST and driver tubes Genalex-Gold Lion B749/ECC82/12AU7 also upgraded resistors to Takman 1% metal film and coupling capacitors with Mundorf MCap Supreme EVO Aluminum and I must say the KT88 tubes is far superior way much better in my opinion and sounds really good than the stock JJ’s that comes on this kit. Listening to new album “Wallflower” by Diana Krall and old album “Orgy In Rhythm” by Art Blakey recorded 1956, Paul Desmond “Bridge Over Troubled Water” recorded 1968 the sound is rich and detailed, superb imaging realistic bass, piano and alto saxophone smoothed good instruments separation the vocal is so clear is just like the singer is singing in front of you large soundstage very clean no noise/hum driving the Triangle Borea BR3 speakers 8 ohms 90db sensitivity and this amp can deliver powerful output rated 8 watts. The source of music are analog out of BlueSound Node 2i streamer with Parasound Zpre3 preamp also tested listening it with EVGA Nu Audio Soundcard analog out with upgraded Burson V5iD hybrid OPamp, the sound of TIDAL MQA Masters lossless audio is superb on all variety of music. Next project is to build a matching Elekit TU-8500 Tube Preamplifier :)
Attached Thumbnails
 

Attachments

  • elekit4a.jpg
    elekit4a.jpg
    893.1 KB · Views: 703
  • IMG_2246.jpg
    IMG_2246.jpg
    982.8 KB · Views: 644
  • IMG_2248.jpg
    IMG_2248.jpg
    815.7 KB · Views: 648
Last edited:
I would simply bypass R43 and R44 with a shortcut made of resistors pins. For higher-end open back Sennheisers, 75-100 Ohm resistors are the best. Note that the output impedance of the original TU-8200 was about 94 Ohms.

I own an 8200R and while the headphone out worked OK with Sennheiser 58X, driving my recently acquired Hifiman Ananda the output was very low, i could turn the volume all the way up and the volume was still low (albeit with a lot of distortion). So i implemented the mod suggested above and the amp now drives my Anandas with ease. I have my headphone jumper set on low, i never did try changing it before the mod however.
 
The 8200R has adjustable output level so if you install a pair of let's say 3.3 Ohm/1W resistors instead of 220 Ohms, you should be fine with lower impedance phones. Modifying the original model is a bit more complicated and I haven't done it yet as I am not sure if I will keep these headphones.

Hi paczeltf - just wondering if you ever made any headphone impedance mod to to the TU8200 original version so that it pairs better with lower impedance headphones. I'll be opening up mine up soon to install the Lundahl, and am considering whether to figure out a mod to make the amp pair better with low impedance planars (eg HE1000).
 
Member
Joined 2018
Paid Member
Hi paczeltf - just wondering if you ever made any headphone impedance mod to to the TU8200 original version so that it pairs better with lower impedance headphones. I'll be opening up mine up soon to install the Lundahl, and am considering whether to figure out a mod to make the amp pair better with low impedance planars (eg HE1000).

I bypassed the 90 Ohm (2x180 in parallel) resistors and left it like that so my phones are connected to the OPT. The output level in this case is too high for low impedance dynamic phones as some background noise is present, but may be ok for low sensitivity planars. (I use HD600s almost exclusively with this amp after a brief affair with HD800S and a longer one with Focal Clears that I still use with portable devices. I will restore the original status when I will be opening the cage next time.)

Output level attenuation while keeping the output impedance low is possible but not with a 100% PCB friendly way.
 
Cheers thanks. I've now bypassed those resistors. The amp is working perfectly with my HE1000 and Aeon Flow closed. No noise through either of those headphones, and there is enough usable range to comfortably use the volume knob (I usually have it around 8 o'clock now, whereas before the mod it was usually at 9-10 o'clock).
 
Just a follow up to my post above. I'm thinking of reversing the change because there is not enough usable range in the volume pot for my relatively low sensitivity headphones (90dB sensitivity) between the lower bound (point where channel imbalance corrects) and the point where it is too loud.

Based on my experience, I'd probably only recommend the mod for lowish impedance + very very low sensitivity (sub 90dB) headphones (eg hifiman he6)

(note i'm using a typical line level source - dragonfly red - 2.1V). Actually before I reverse it I might try reducing the dragonfly red volume (bit perfect) to reduce the source level, and see how I go.
 
Last edited:
Member
Joined 2018
Paid Member
Mine did not have channel imbalance, at least until I upgraded to a TKD that later replaced with an Alps RK27 for the same reason.

The problem with restoring the original configuration is that many headphones do not sound great when being driven from an output impedance that is higher than their rated impedance.
 
Member
Joined 2018
Paid Member
Yes if you have low level channel balance issues. The RK27 is very accurate, I measured my sample and it was well within specs in all positions. It is much bigger than the stock pot though so you will need to cut that piece from Unit-2 and connect it with wires.

There are a couple other ways to decrease headphone output level.

- If you use it with 8 Ohm speakers, changing the speaker impedance to 4 Ohms while listening with phones gives you about 3 dB lover level.

- If you bypass the 90 Ohm resistors with a 15 Ohm/1W resistor, and also connect the headphone output to the ground via another 15 Ohm resistor then you will get another 6 dB attenuation. I would have done this myself if my main phones weren't HD600s.