Thieliste's new Reference system

Argonaut · Jun 16, 2024

Thieliste said:
Yes I know it can get much worse but since this red plating is moderate I wasn’t sure.
Do I have to change only this tube or the pair ?
Thanks

A defective KT120 is one possibility , The other being that there is nothing wrong with the valve per se , and that there may be a slight problem with the bias circuit for that particular tube causing it to draw more current than is specified .

The quick and dirty way of diagnosing the latter , replace the KT120 with a spare and observe , should the spare overdraw and red plate it would be unlikely to be another defective tube and would indicate a slight problem with the bias circuit .

If you don’t have a proven ‘good’ spare KT120 then by merely swapping the recalcitrant tube around with one of the other KT’s would achieve the same end , caviat , don't run the amp for any longer than to prove the experiment , a couple of mins should be long enough.

Thieliste · Jun 16, 2024

Ok I swapped the pair of KT120s and it’s not red plating anymore.
Peharps bias was not settled during the first day yesterday because I was using KT88 before that.

Argonaut · Jun 16, 2024

Thieliste said:
Ok I swapped the pair of KT120s and it’s not red plating anymore.
Peharps bias was not settled during the first day yesterday because I was using KT88 before that.

Doesn’t quite work like that , so neither KT’s are now red plating including the one that you swapped into the previous red plate socket correct ? How long did you run the amp ?

Thieliste · Jun 16, 2024

Argonaut said:
Doesn’t quite work like that , so neither KT’s are now red plating including the one that you swapped into the previous red plate socket correct ? How long did you run the amp ?

That's right none are red plating anymore, i ran the amp a couple of hours.

Thieliste · Jun 17, 2024

Ok guys very strange situation here, when I put back this tube in it’s place it does red plate but when I swap it doesn’t do it.
I have no explainations.

Thieliste · Jun 17, 2024

Should I ask Jadis to change both tubes ?

Argonaut · Jun 17, 2024

Thieliste said:
Should I ask Jadis to change both tubes ?

I think that would be a start If availible to you ? Are you still under warrenty ? If so all good , if not , a word with Jadis regarding your issue would be progress . Do you have a circuit diagram for this model .

Thieliste · Jun 18, 2024

Argonaut said:
I think that would be a start If availible to you ? Are you still under warrenty ? If so all good , if not , a word with Jadis regarding your issue would be progress . Do you have a circuit diagram for this model .

Obviously they are still under warranty, they are not even a week old.

Argonaut · Jun 18, 2024

Thieliste said:
Obviously they are still under warranty, they are not even a week old.

Thank you , I wasn’t aware of that , good luck.

Thieliste · Jun 18, 2024

Argonaut said:
Thank you , I wasn’t aware of that , good luck.

Yes they replaced a full set of Psvane KT88C also from Jadis that went bad.
Looks like a i have no luck with tubes selected by Jadis lol
I have a set of Psvane Acme KT88 that i purchased in Germany and they work just fine.

Thieliste · Jun 23, 2024

Ok guys my problem is solved, I moved the back pair to the front and vice serva and that did the trick no more red plating.
Been burning them for about 100h they sound fantastic, much better than KT88s not even close.

Thieliste · Jun 23, 2024

For the preamp part I tried NOS Mullard, Tungsram, Brimar, Radio Technique and RCA.
Here again RCA smokes them all by a wide margin paired with the KT120s.

Robertd · Jun 30, 2024

I think it’s great that you’re building a reference system around the 3.7s. I loved them when they came out, but I didn’t have the space for them. And then Thiel imploded. I had the 1.6 then and still have them and run those with a VAC Renaissance 70/70.

Would love to hear how it’s sounding through you’re Jadis.

Thieliste · Jun 30, 2024

Robertd said:
I think it’s great that you’re building a reference system around the 3.7s. I loved them when they came out, but I didn’t have the space for them. And then Thiel imploded. I had the 1.6 then and still have them and run those with a VAC Renaissance 70/70.

Would love to hear how it’s sounding through you’re Jadis.

Hi Robert, many thanks yes the Jadis is definitely the best amp i've had to date for my Thiels even much better than the Audionet Humbolt that i home demoed.
It's insane how much current i have with the KT120s and it's never harsh.
It took me 3 years to find the right amp for my 3.7s, its was not an easy task but i'm very happy now.
Several years ago i never thought i would go the tube route as most Thiel owners use powerful SS amps to drive them but here i am today and i will never go back to SS.
I'm still amazed at how these speakers can sound when you drive them with the right amp.
You also made a very good choice with the VAC for your 1.6s

Thieliste · Jun 30, 2024

I purchased plenty of NOS input tubes as my KT120s are now burned in.

Thieliste · Jul 25, 2024

Ok guy after several weeks of input tube rolling I finally settled on RCA Black plate 12au7 preamp tube.
This is by far the best NOS preamp tube I’ve ever tried, it is very smooth, liquid, open, transparent from top to bottom.
Musical engagement at it’s best.

Thieliste's new Reference system

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