I built this TU-8500 Stereo Tube Preamplifier Kit. Now for evaluation

sanford12

sanford12

Old Stuff New Stuff As long as it's Good Stuff
Subscriber
I'm seriously considering this kit. It gets good reviews and looks like great value. Tube Depot also gets kudos for their service after the sale. Anyone one with experience building and use or if you've heard one your thoughts would be appreciated. Thanks
 
Register to hide this ad
I have built these before. Very solid unit, I recommend using a good solder like the Cardas Quad Eutectic. The one mod I made to the ones I build is to change the sleeve for the shafts with grommets, apply some lithium grease to the shaft where it goes into the grommet. Much better and more professional feel. Also upgrade the op-amps in the phono stage for a better unit, I have used LM4562NA or OPA2227 with good results.
 
It sounds very good, I swapped the 5965 tubes for some Brimar 6060 tubes. It sounded vastly better. It a swiss army knife of a pre amp. Lots of features and selectable gain. I think you will be very happy with it.
 
It looks like a well put together kit, with good documentation. I'd build it just for the satisfaction. It has tubes in it and that's awesome, but having just read the review it seems that the RIAA stage is all opamp based, and that the tubes are mostly acting as a buffer on the output. Don't let that stop you, just be aware that it's more of a hybrid design than a true tube preamp.

That being said, you are getting a lot of good stuff at a reasonable price, not the least of which is the experience of building it. I'd say the Elekit is going to be a fun step in your journey but probably not your destination. Your mileage may vary.
 
I ordered it today. Downloaded the assembly manual. Looks straight forward and it states 4-5 hours to build. You can tack on another 3 for me doing it.
 
Noteworthy experience: A friend and member of our audio group built a premp with audiophile grade solder. He couldnt get it quiet and he kept losing a chanel. I looked at it and couldnt figure it out. The fix which finally solved the issue, another tech sucked every joint dry and re soldered it. My friend never had another problem with the preamp. I use Kester old fashioned lead solder, rosen core. I buy it by the pound from mouser. I have some good friends who are audiophiles but the solder NASA uses is good enough for me, and it works every time, with every component...
 
Ordered one last week from VKMusic. Went with the resistor, opamp and Mundorf caps upgrades. Friend is building it as he wants listen to for a bit and I'm snowbirding for a while. If it is as nice as the reviews I've read I'll likely go with a matching TU-8340 PP amp.

If it really is that good I wonder if the Khozmo 64-step motorized attenuator & boards would fit? Do me good to get up and turn the volume knob.
 
Last edited:
I may change the caps and since it's sockets for the IC's I'm gonna wait till I hear it first. Be here on Monday. Should be fun.
 
Well here it is Tuesday and I'm sitting here listening to a freshly finished preamp. Been running about an hour. It's cut the slight hiss that the Outlaw as a pre had to next to nothing. This pre has a bottom end that the Outlaw can't match and really nothing else I've heard and that's right off the bat. It may be the solution that the Kef 950's need to be their best and they're sounding awfully good right now. If it's this good with no break-in and chinese 12AU7's this will be one hell of a buy. Got some nice double mica 12AU7's waiting and some Phillip's 12AT7's on the way. I'll get some hours on it then tell ya what I think.

They said 4-5 hours to build but it was 10-11 for me. I was very anal slow and precise. Still managed to put 3 parts in wrong but since I checked each piece after soldering it so things were corrected right then. This build is fairly easy if you have some soldering skills but it's not something to learn on. I used Radio Shack 60-40 rosin solder and I really like it. Bought a bunch when they had the going out of business sale. Good stuff.
 
Last edited:
sanford12 said:
Well here it is Tuesday and I'm sitting here listening to a freshly finished preamp. Been running about an hour. It's cut the slight hiss that the Outlaw as a pre had to next to nothing. This pre has a bottom end that the Outlaw can't match and really nothing else I've heard and that's right off the bat. It may be the solution that the Kef 950's need to be their best and they're sounding awfully good right now. If it's this good with no break-in and chinese 12AU7's this will be one hell of a buy. Got some nice double mica 12AU7's waiting and some Phillip's 12AT7's on the way. I'll get some hours on it then tell ya what I think.

They said 4-5 hours to build but it was 10-11 for me. I was very anal slow and precise. Still managed to put 3 parts in the wrong but since I checked each piece after soldering it so things were corrected right then. This build is fairly easy if you have some soldering skills but it's not something to learn on. I used Radio Shack 60-40 rosin solder and I really like it. Bought a bunch when they had the going out of business sale. Good stuff.
Click to expand...
12at7 is the wrong tube. It's designed for 12au7 / ECC82
 
MX117.MC7150 said:
12AT7 is the preferred tube according to Victor Kung, the NA distributor and this review:
https://wallofsound.ca/audioreviews/review-elekit-tu-8500-tube-preamplifier-kit/#prettyPhoto
I have some NOS Sylvania 12AU7 and JAN Phillips 12AT7 to roll thru mine.
Click to expand...
I am skeptical, he also claims "12AT7 tube. This is a lower noise version of the 12AU7." which is plain wrong.
12at7 fits, it won't damage anything but the tube will operate in a non-linear part of it's region.

In retrospect, as the both tubes are working in near cutoff region due to very low current
they might be as bad.
 
Last edited:
Am sure Sandford12 & I will let you know our thoughts on the "great 12AT7 vs 12AU7 controversary" once we've rolled a few tubes. Will be several weeks for me as I am traveling to the warmer climes shortly (only crazy people live where its cold ;)).
 
MX117.MC7150 said:
Am sure Sandford12 & I will let you know our thoughts on the "great 12AT7 vs 12AU7 controversary" once we've rolled a few tubes. Will be several weeks for me as I am traveling to the warmer climes shortly (only crazy people live where its cold ;)).
Click to expand...
Yes, that's good. Some measurement would n´be nice, what voltage on the B+ ( plate supply ) ?
Is it really 140V ? That confirms that the tubes are starving and unlinear. ECC83 should fit
better, output impedance is already high.
 
Last edited:
I couldn't tell you. Found it on this film archive.
https://archive.org/details/movies
It's a very compelling image.

Hi-Figuy's recommendation to use grommets instead of the sleeves for the volume and output shafts is a good one. It feels a little cheap when you use the sleeves. The grommet adds some friction and just feel better.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom