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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Audioromy FU13 (813) diagram and mods

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Wow - Great!

I have surfed past Rören und Hören previously but obviously not found the right threads. There is lots of stuff there. In Norway there is a lot of interest in the Music Angel KT88, but it seems Germany is the place to go for Audioromy.

However, I see that I will have to brush up on my school german as google translate looses about half of the meaning.
 
Mine has 6n6p drivers;) , of course.

An externally hosted image should be here but it was not working when we last tested it.


Below the parts i have replaced until yet.

- Volumepotmeter. After 2 months it started to crack, replaced with Alps 100k LOG 2 channel potmeter.

- 47uf/40 V Capacitor to control on/off relais.

An externally hosted image should be here but it was not working when we last tested it.


If this one is defect, the relais switch at 100hz and the fuse is blown.

- Rectifier tube was defect after 4 months, changed for another.

- Changed 6DJ8 tubes for JJ E88CC goldpin.

- Changed ECC82 for 6N6P. Must modify the heater powersupply.

The last two modifications are to change sound and this is very personal.
 
Guess I´ll have to start tracing one from the amp then, it´s a good way to get to know it anyway.

About tube exchange you were talking about ecc99 needing more heater current. But you don´t need to do any changes in the amp, so it will run cooler, is that correct?

I want to buy a set of tubes for the amp and keep the originals in reserve. Would this be the best set:
a more linear input ecc99
Drivers Ecc88 - what is the effect?
Rectifier as standard
and Output 813s - Find something for better longevity I have heard the FU13 only last 2-3000hr
 
The ECC99 needs MORE current so the amp will be a little hotter. You do not have to change anything. You got less distortion and more linearity and more dynamic/drive.

The tube setup is very personal. Do not change the brand for the FU13. We treid about every 813 tube we get our hands on but the shuguang FU13 sounds the best.

For the record:

The 6dj8( ecc88 or ecc85) is the inputstage.
The 12ax7 is the driver.
 
NFB = negative feedback. Usually a loop from output back to input, where it is more correctly called "global" NFB, but can be local as well, e.g. round two stages. NFB can reduce distortion but it may not always sound better and can also introduce instabilities. The simple solution with innately low distortion triodes is not to use it. With pentodes it has much more popularity, and with solid state devices it is almost compulsory.

andy
 
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