Building the TU-8900

Tube amps require some load. Connecting headphones with impedance up to about 30 Ohms to the speaker taps is fine, but you should add a parallel resistor with high impedance phones. If you use the headphone output, it will be done automatically.

Thank you very much! I figured it out. Now the next step is to wire balanced in transformers to SE…to make it work with this amp. Has anyone tried that ?
 
So as promised. I have uploaded a PDF detailed build here including all the modifications and so on. You can download it and check it out. It may help others who are interested in building this kit as well
Click the link above to download , and it is 1GB!!

This link is broke

Please use this link
Thanks for the respond. I was too tired and didn’t check. Here it is again
I thought about the external solution, but I wanted to keep the purity and integrity of the signals. So, here it is internally
 
I am glad to share. However, I have a problem with Jensen transformers. These kinds are too sensitive and can cause hum if nothing is playing and volume pots are cranked to more than 80%😢. Will have the Lundahl coming and see if it is going to be any better. Crossing fingers
 
Ugh, I shouldn’t just blame on the Jensen right away lol!!! Anyways, experimenting and trying modify the amp are both not an easy tasks. They perhaps work as they should when building a separate box for them. There is something funky going on here and it isn’t the Jensen faults. I will wait on for that Lundahl and see if I can do anything further
 
Nice !!!! Been thinking about also getting WE 300B, but right now
I am fixated by 2A3 sound. RCA 2A3 is to die for. I have 1971 date code and it opens up 8900 to another higher level of 3D soundstage. Don’t get me wrong Cossor/Linlai 2A3 is very good and you know noise and microphonics will be good……buying any RCA NOS these days is a gamble unless seller guarantees no noise and microphonics.
 
I use NOS ECC82 Tungsram and also NOS Mullard 12AU7. No experience with RCA clear top. In my system with easy listening mostly vocal music, both are great, Mullard gives slightly overall smoother presentation and bit more details slightly larger soundstage maybe. But Tungsram performs well for the money. This is driving RCA 2A3
 
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For 12au7 I have tried Mullard cv4003 box plates and Brimar 6067 T version I only ran each for a couple of hours as did not want to put lots of hours on them and that was in the first 25hrs both sounded good. 99% or time I've been listening with the Sylvanian 12bh7 over 200hrs so far so will be sure to try the 12au7 again. I've been wondering about using E80cc as have some very nice ones but have not checked the data sheets yet.
 
These are all good tubes :) Let me add some others I have tried :

GE 5814A - nothing to brag about
Cifte 12au7 - reminds me of NOS Mullard 12au7
Mullard NOS CV4003/12au7 (Eico or Hammnd logo, found in organs) is probably the best with detail and adds some warmth to those bright systems.
RFT 12au7 - been a while since I heard these but I felt the soundstage decreased and lost detail
Bugle Boy 12au7 - this is one of the best 12au7 like the Mullard NOS but where the Mullard is detailed and warm, the Bugle Boy can be bright at times and mezmerizing with all the detail it brings out. Excels at 3d soundstage
Psvane 12au7 - this is a real sleeper, sounds probably 80% like a NOS Mullard but without the hefty price

Has anybody had any experience with rca grey vs black plates ?
 
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