Building the TU-8900

Having been so favorably impressed with the 300B in the TU-8600 I began testing the 8900 with the WE300B. I went through a test sequence of a) contemprary music with strong electric bass (Lenoard Cohen 10 New Songs) b) Jazz (Christian McBride Trio), and classical (Vivaldi Oboe Concerto). All recent recordings. Using 99dB @ 2.83V / 1m Klipsh Forte III speakers.

As soon as the first track started on the 8900 (300Bs) I could hear a marked improvement over the 8600. Nothing all that specific, but it seemed that all the outstanding qualities of the 300B were elevated: great bass, solid/clear mids, and impressive hights.

But, then I tried the same sequence using the 2A3s. The differnce was remarkabe. I agree with Neville, this takes things to a another level. Bass was smooth and mellow, not as pronounce (booming, sustained) as with the 300Bs. Mids were increadibly transparant and the highs were brilliant but not shrill. There is a clarity and a detail that brings out every instrument and elements of the music that I had never heard before.

These are only first impressions fained after just a few hours of listening. But, I have to say that this is one of the best, if not the best amp I have every heard. And with the 2A3s, well, not much more needs to be said.
 
@Neville and @FrEdward, thank you much. Will stay tuned for more updates from you and others.

@odamone, the stock version of 8900 costs a little over the stock version of the 8600, and I am guessing it is due to the auto-bias circuit on the 8900.

$1500 price tag of the 8900 is the stock version. While the ~$2000 price of the 8600 is with the Lundahl OPT and a couple other upgrades.
 
I am leaning to upgrade the resistors to PRP (series PR9372) which have 1% tolerance.

I used the PRP resistors in my TU-8200 rebuilt and really liked them. From what I recall there are both 100ppm and 50ppm versions, I went with the 50ppm as the cost difference was minimal. I rally liked them but I did sense that some listeners would find them overly detailed or bright.
 
Having been so favorably impressed with the 300B in the TU-8600 I began testing the 8900 with the WE300B. I went through a test sequence of a) contemprary music with strong electric bass (Lenoard Cohen 10 New Songs) b) Jazz (Christian McBride Trio), and classical (Vivaldi Oboe Concerto). All recent recordings. Using 99dB @ 2.83V / 1m Klipsh Forte III speakers.

As soon as the first track started on the 8900 (300Bs) I could hear a marked improvement over the 8600. Nothing all that specific, but it seemed that all the outstanding qualities of the 300B were elevated: great bass, solid/clear mids, and impressive hights.

But, then I tried the same sequence using the 2A3s. The differnce was remarkabe. I agree with Neville, this takes things to a another level. Bass was smooth and mellow, not as pronounce (booming, sustained) as with the 300Bs. Mids were increadibly transparant and the highs were brilliant but not shrill. There is a clarity and a detail that brings out every instrument and elements of the music that I had never heard before.

These are only first impressions fained after just a few hours of listening. But, I have to say that this is one of the best, if not the best amp I have every heard. And with the 2A3s, well, not much more needs to be said.

You described the 2A3 better than I did and agree with everything you said.

As for 300B comparison I too heard a difference but couldn’t tell if it was due to the difference in caps and different tubes.

I have Sylvania 12au7’s and plan to swap them in, later I might get 12bh7 from Victor.
 
Unfortunately not. I looked everywhere. So i email elekit asking them to send me. In the meantime, i just go ahead completing the amp without the leds. Now i am listening to it. Very happy with the quality on EH300B. Now looking to buy 2A3. Thanks for asking.
 
Sorry to hear that but it’s very uncommon for this. Japanese kits are usually precise. I have not heard EH300B but glad to see you looking at acquiring 2A3, to me and others here it made a remarkable difference. I will keep my Cossor 300B as backup but already looking at other 2A3 tubes. Let us know what you get and your impressions of it.