Low microphonics 12ax7 for V1 use?

I have had good luck with GTs, EHs, JJs and Tung Sols. They may not always sound the best, but for the most part they've been sturdy.

 

Sovtek 12AX7LPS - 'long plate spiral' filament, meant to be quiet. The 12AX7B is meant to be selected for low noise, too. Mesa SPX also 'special selected' although I think they're JJ which most people don't seem to highly regard in V1

 

If you're comfortable working on a live amp; try moving the wires connected to V1. Sometimes the placement, or lifting off the chassis, of certain wires will lessen or rid the amp of microphonics. Use a plastic or wooded probe to do this. ;-)

 

All of the above is correct and also did good with a Mullard RI.

 

TubeDepot (no affiliation, etc) has a "low noise/microphonics" option on their preamp tubes that I've found very useful.

 

LPS= LONG PLATE spiral

Longer plate = More gain and potential for microphonics.

From the tube store on the Sovtek LPS

The tube store on JJ ECC803s (long plate)

OP- Look at the lead dress on the tubes in the amp. The lead dress can affect microphonics greatly. Also, sometimes the tube shield causes microphonics. I ran into that issue on my Hiwatt.

 

Oops you're right. I was thinking noise not microohonics for some reason.... Not enough coffee today.

 

TAD (Tube Amp Doctor) sells rebranded Chinese (Shuguang) tubes that have been tested and labeled for low microphonics and so forth. They're not too dear. For example, the 7025 is the classic "hi fi" low noise tube. I think their 7025 WA would be their best. Check out their website.

There's also PM tubes, which are another line of rebranded Chinese tubes. They're even less expensive than TAD's. In the US, they can be acquired through Tube Boutique: https://www.tubeboutique.com/preamp/

 

+1 on the TAD 7025wa

After looking for issues with the lead dress.

 

Are you dead set on a 12ax7 at V1? 5E3 "normally" uses a 12ay7 at V1, not that the lower gain tube can't be microphonic.

 

Avoid the long plate Mullard and Mullard style designs. I've had microphonic issues with those.

Tung Sols seem quietest of the bunch of new cheap tubes but the glass on those can be chunky and not fit the can if the amp has one on V1.

As mentioned above Mesa do a selected SPax7 low microphonic tube esp. for V1 in high gain amps. I quite like Mesa tubes even if they are JJ/Chinese these days. Even the standard ones don't get microphonic in my high gain Boogie.



I think the rubber jacket is largely cosmetic but it might do something

 

I prefer the 12ay7 at v1 as well.

 

++ on TAD 7025wa, their short plates and also slightly lower gain than most 12ax7 types which means less noise and subsequently less prone to microphonics.

Hunt around though and you might find a ANOS GE 5751for $10-15 more, that's what they were designed and built for, low noise and microphonics in military communications use. Many ruggedized with extra support rods and extra thick mica to withstand vibration, one of main causes of tubes going microphonic in combo amps. Go for the short plates.

 

Been using a 5751 "low noise" option from t-depot in V1 and love it!

 

Another happy TAD 7025wa guy here. They go in all my amps.

 

^^ This.

I don't care for 12AX7's in 5E3's - or most tweeds - in the V1 position. Much harder to control and a thinner type of sound to my ears. The interactivity of the controls also becomes far less useful - you can't fatten up the sound the same way.

 

I also have the VHT 5e3 clone. I changed out all the tubes except rectifier for tung sol. When I first got it I noticed a lot of noise. I think the tube change helped but I've made so many mods it could of been something else.

I haven't tried a 12ay7 in V1 but would like to. The VHT has a pretty high negative feedback resistor on the bright channel of v1 so this helps tame the gain some.