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Switching Tubes


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Hey there

I've had my SV mkii 212 for about 3 months now. I bought it used in great condition, 

And ive noticed that its not as loud as it use to be. 
Its time to change tubes

I Want To Hear Your Opinion before i make it up my mind


Im thinking of getting a pair of Winged SED 6l6GC and a pair of Tung Sol 12ax7


Should i Get the Stock Tubes or should i get these high end Tubes?


I know its going to change my tone a bit.


Has anyone tried this? What were your results?


What tubes did you put in your sv mkii?



Thank you for your time 


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Changing the tubes on a SV will change the tone, as it will on any tube amp.  However, the tube amp in the SV series is intended to be pretty transparent.   The SV series uses full amp and cab models, meaning that the pre-amp, power-amp, and cabinet is fully modeled.  The tube amp is just coloring the tone on top of that.  It may not have as drastic of an effect as changing the tubes on a regular tube amp.


For example, the 12ax7's in a regular guitar tube amp are fully involved in creating the unique sound, whereas the 12ax7's in the SV are there simply to boost the final fully-modeled signal before it hits the power amp tubes.  So, changing the pre-amp tubes on the SV may not have the same amount of effect as it would on a regular tube amp.


When I got my SV, I put in a pair of matched JJ 12ax7's.  They were a bit darker, and had just a bit more break-up at volume.  I set up all my patches using those, and it sounded great.  So, when the time came to change 'em out, I just stuck with another pair of matched JJ's because I didn't want to adjust all my patches.  Same for the 6L6's.  I used the stock ones, and replaced them with the same.

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  • 2 months later...

Here's a good read... They actually have "matched" 12AX7 tubes! Which wont really matter on the SV, but I got them anyway! LOL! I put the 5751 in the phase inverter slot or V2 and a Tung Sol in the "power boost" slot or V1 and then a nice Mullard in the SV Pre. I also put a set of Groove Tube 6L6's in. All of this made a definite improvement on the amps tone. Not like night and day but it is noticeable. Did it about two years ago and it stills sounds great!


cgtrox B)

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I treat all my tube amps the same way now....Mesa 5881s, EL34s, EL84s and SPAX7s (SV MK1, MK2, DT50 and DT25)...However, I use GT-SAGAX7 (balanced inverter) for the inverters...But I cannot tell any difference between the SAG and the SPA in terms of inverter usage...the cost is identical between those...Always had good luck with Mesa tubes since the late 80s.

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  • 2 weeks later...

I retubed mine with JJ Tubes from Eurotubes and it sounded much better.  Less harsh and more responsive/thumpier.  I couldn't be happier.  Mine were practically brand new too.  I've just gotten into the habit of switching all my tubes over to the JJ Tubes right away.  I also biased the tubes as they were biased a little cold from the factory.

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Bought a used SV mkI, I've been tempted to try different power tubes on it, does anyone know what plave voltage the am runs?

anyone tried a 6CA7's?  


Another question; will it sound bad if you don't bias SV with tube replacement? since it's got a modelling cab and preamp I'm not sure if bias has any effect?

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  • 3 weeks later...

The other guitarist in my band also got a Mesa SPAX7A in his MK2 now.

We switched tubes (my SPAX with his 12AX7) and did a "before and after" comparison and the absence of noise is simply brilliant. He immediately order the tubes too

(and so did I, just to have a spare one). :-)

Just replace the #1 tube and be amazed!

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  • 3 months later...
  • 6 months later...

I just replaced it with this: - it could be my imagination but it really feels more responsive due to the pure absence of hiss/noise.


Or it is just my imagination. ;-)


Did the same thing on V2 .. replaced with a MESA 12ax7 ... more low end, sounds "heavier".


Tried a RUBY brand 12ax7 in V2 and it sounded frigging horrible.


Had previously tried the MESA in V1 and that sounded horrible.


So ... it seems like .. if you want to play .. play with V2 (12AX7 on the left).


SOVTEKs are know for being transparent ..... I assume MESAs are "built for modern, heavy gain."

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  • 1 year later...

Im way late to the party, but glad to have found this thread. Im gonna try two Mesa SPAX7A in my Mk1 212. The sound has been muddy for awhile, and distorts in a bad way at higher volumes.

Replaced the power tubes last year with a pair of sovteks, rebias it myself thanks to a wealth of information on the internet. So that leaves the 12ax7s or the speakers.

I just started  running a pod hd into the power amp, for more flexability, and it seems to worsen the effect at even bedroom volume. Perhaps the pod outputs higher than the dsp in the amp?

It could be the speakers, but the cones look nice and are still soft to the touch. So gonna try the mesa tubes and hear how she sounds, its alot cheaper than speakers.

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