[EV-MAN]

Got a AVA Ultra SL Hybrid Tube Preamp built around 2005. Put two new JJ ECC83S tubes in. Lows and mids sound good highs are a little distorted. Wanted to try a different tube so many to choose from Mullard is the only one that says it works well with home audio. All the rest just speak of guitar amps. What do you guys think? What should I try. Thanks Bill

[Listens2tubes]

Look for original Mullard 12Ax7 or ECC83, gold pin. Or Telefunken ECC83 or ECC803s. I had great success with Mullard 10M series 12AX7a on my Super Pas 4i turned T8 phono section, though they can be prohibitively expensive.

[avahifi]

I think you are using the wrong tube type if you put ECC83/12AX7 tubes in the line section.

The line section should use 12AT7 tubes, the phono section 12AX7 tubes.  12AX7 tubes in the line section will have too much gain and will be run too hot and too hard.

Frank Van Alstine

[Ericus Rex]

EV-man,

You need to give new tubes 20 hours of break-in, at the absolute least, before making any judgments about their sound.  Highs usually tame themselves during break in and bass often will get tighter and soundstage will often expand.  Many say tube break-in takes 100 or more hours but you can get a sense of the direction the tube is going in after about 20 hours.

[avahifi]

Note that the back panel label for the preamplifier should tell you which tubes to use.

Frank

[EV-MAN]

They are correct I have JJ ECC81 tubes in line section and JJ ECC83S in the phono section. I have no past experience with tube. I will be patient and break them in and listen to what happens. Thanks for your help and if anybody thinks of another tube worth trying let me know. Thanks Bill

[EV-MAN]

Being patient has paid off. Probably have put around 30 hrs the last two weeks and it sounds a whole lot better.

[festuss]

Highs are a little distorted?  Why would that be, from a BAD tube not  a tube that is of a particular brand? Or bad source material.  My Ultra Hybrid pre amp are still using the original factory JJ and there is no distortion, why would a JJ versus a Mullard distort, unless it's a bad tube. Or another issue that has nothing to do with what tube is in place

[EV-MAN]

I have no clue why. I have never owned any tube gear and know nothing about them. But as I got some hours on the new tubes it improved a lot.