Mullard 12AX7 tubes

Fer1000

Fer1000

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I have changed the original tubes 12AX7 in my preamp (JJ tubes) for the Mullard 12AX7 and in the first hours they were very good.

Nice improvement on mids and trebbles and no changes on Bass but regretfully after 80 hours the sound have changed a lot.

Now there is too much bass present I was forced to change the tone controls in my preamp from Bass 0 to Bass -2 now.

Is there an estimated time to complete break in this kind/model of tubes.?

I really do not know what to do... If I need to wait more hours to see if there is a final improvement on bass and general sound or just to install again the original tubes.

The original ones were very good for me but I have done this change expecting improvements.

Thanks in advance for your cooperation... I´m new with tubes.
 
Preamp tubes can take 50-75 hours before finally settling in. I know it seems like a long time but definitely give it more time.
 
Thanks for your comments..!!!

Now they have 80 hours and the sound is not good.

In the very beggining they were very good but now regretfully there are too much bass.

I will keep them another 50 hours to see what happen.

If they do not get better I will install again the original ones JJ in my preamp.
 
Interesting turn of events. Sorry you aren’t crazy about them.
 
tube rolling......... be careful it can put a large dent in your wallet !
 
I didn't notice a change in mine (Platinum Grade, from Upscale) - but they certainly have a notably darker, warmer balance than most other 12AX7 variants both old and new.
 
mulveling said:
I didn't notice a change in mine (Platinum Grade, from Upscale) - but they certainly have a notably darker, warmer balance than most other 12AX7 variants both old and new.
Click to expand...
This was my experience, too. As in too much for my taste, which leans toward liking warm and dark.
 
In relation to this topic, I have changed the 12AX7 of the preamp segment of my Vincent SV700, for current 12AX7 Mullard (Manufactured by New Sensor Corporation in Russia). The improvement was very noticeable, greater dynamics, greater instrument separation, greater extension and control in the bass. They will be in about 40 hours of break in, so I keep waiting and listening to see if there are any major changes.
Everything has turned out positive for the moment.
The source is a Lumin T2 and the Tannoy 615 MKII and Sonus Faber Venere 2.0 speakers
 
Mullards tend toward the warm side, and can be very good in certain amps / preamps, and can be boomy in others. I love them in my VAC Sigma 160i SE. If you research the 12AX7 types out there on audiotubes.com, you might find some more suitable tubes in your preamp. As a general rule, German tubes tend to be more detailed with tight bass; British tubes are more warm, American tubes are sort of in between.
 
Many Thanks for your advice Scotty.!!!

Do you have some idea of how much break in time they require..?

Best Regards;
 
Fer1000 - I have never noticed a need to break in tubes - others say they sound better after about 15 hours, and the power tubes (output tubes) even longer. After they get up to operating temperature, in my opinion what you hear is what you'll get. The equipment also needs to warm up. Of course, my ears are getting old - so
 
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