SPAX7 in Mark IV - V1 position

[LittleJohn]

Hi all,

I "heard" the SPAX7 was the best thing to get for low noise goodness BUT
it wont fit within the sheild casing in the V1 position . ( SPAX7 is too fat )

Should I infer the SPAX7 is not intended for use in the V1 position ??

Anyone been down this trail ?

thanks in advance.
--John

 

[KH Guitar Freak]

Not sure about the Mark IVs, but they fit fine in my Roadster, and in the Stilettos too...

 

[LittleJohn]

they fit fine in the Mark IV also,,, in sockets V2 thru V5.

I am hoping to find out what ( if not the SPAX7 ) works well for socket V1.
I am not an electrical engineer, but I imagine it is probably not a good idea to get rid of the metal can .<?>

According to the docs, the V1 socket requires a low-noise high grade 12AX7.
V2 thru V5 can have "ordinary" 12AX7's.

thanks for the response, I will keep poking around and see what I can learn.

 

[crane]

The metal can is a shield for less noise. You can try without it, and if you like it there's no other problem.

 

[EvoLove 34]

they fit even though they have that rubber coating. I currently have one in my mark iv. it just takes a bit of finesse to get it to slide down straight without catching the coating on the lip of the metal surround.

but they do fit.

 

[fleeced]

The metal can is a shield for less noise. You can try without it, and if you like it there's no other problem.

and if not try a Tung Sol ... Very smooth and low noise

 

[fdesalvo]

Old topic, but for future reference it's ok to remove the rubber sleeve. I've done so with no ill effect. May be a bad idea in a combo format, where vibrations may contribute to microphonics.

 

[Anonymous]

The metal can is a shield for less noise. You can try without it, and if you like it there's no other problem.

and if not try a Tung Sol ... Very smooth and low noise

+1000

 

[dodger916]

The metal can is a shield for less noise. You can try without it, and if you like it there's no other problem.

and if not try a Tung Sol ... Very smooth and low noise

+1000

+ 1 more. You can find fair deals on good vintage ones.

 

[kungfujews]

They do fit...close though - I've just replaced the V1 in my MKIV B, it was a squeeze! Worth it as the noise reduction is noticable.

 

[mikey383]

Old topic, but for future reference it's ok to remove the rubber sleeve. I've done so with no ill effect. May be a bad idea in a combo format, where vibrations may contribute to microphonics.

That rubber sleeve is why it's branded a SPAX7, and not a regular 12AX7. Keeps the microphonics down.

Don't buy into the hype. It's still a regular 12AX7, you're just paying extra for the rubber sleeve.

 

[droptrd]

I knew it.

 

[jpdennis]

I use the off the shelf TAD 7025-S in all but the Reverb & PI. It works very well for all my Mesas. The Reverb I play with based upon the tank and amp. The PI has the balanced TAD 7025-S and I noticed an improvement in the Heartbreaker and the .50 Caliber for power. The Mark III however, seems a little weaker with the balanced TAD in the PI. This weekend I am doing the old TAE approach with several of the other tubes (preamp & power) I have to see if I can wake the Mark III up. I am hoping it isn't a bad TAD, which can happen from time to time with any tube, but I will find out one way or the other.

Dennis