Question 12ax7 preamp tube differences?

[ivbenaplayin]

Once again I come to the forumites for advice/opinions...

My amp's preamp tube crapped out on me Saturday night without warning of any kind (worked perfectly the night before...) and now I have to replace it. I've been checking into a replacement part and I'm a little confused since there are so many available. After researching on the internet today, I've got the basics about the differences in gain, but my biggest worry is sound/tone characteristics. Is there a big difference in the sound between the manufacturers? What would you folks recommend? The amplifier is a SWR SM-500. Will it really make any difference which brand I use (as long as I use a 12ax7 tube...)?

BTW - When we pulled into the gig and saw where we were playing - I immediately thought of Bovinehost... We played in a really killer dairy barn that had been converted into a dance hall with beautiful hardwood floors and a kick-a$$ bar/lounge in the back! I'll try to get some pics from the guys to post...

Thanks, Eric

 

[Kirby]

While, I have never owned that particular amp, I love my NOS Mullards in my Demeter VTBP-201, but they were pricey. I have a NOS American RCA in my Alembic F-1X that really warmed up the tone there. The Alembic had a Ruby tube in it if I remember correctly when it was new and the Demeter had a form of Groove Tubes when I purchased it used. I love the tone I get with the Mullards and the RCA really turned out to be a great sounding well rounded tone tube for the Alembic. The RCA was about a fifth of what I paid for each Mullard.

With all this being said, I would double check that it is actually the 12ax7 that went out. I have been playing for over 20 years and have never had a pre fail. If it is the 12ax7, see if any of your friends could let you try a couple of tubes to let your ears be the judge. Any 12ax7 should work, but there are subtle differences that only you will be able to decide if you like or not.

 

[Aussie Mark]

I owned a SM-400 and experimented with different preamp tubes, including an expensive NOS Mullard. The conclusion I reached after trying 6 or 7 different tubes is that for live rock gigs an expensive preamp makes little difference to what you hear on stage or what anyone else in the venue hears.

In your living room, or for recording, there is definitely an audible difference though. If you are planning on using the SM-500 to record, it would be worth experimenting with a few different preamp tubes to see which one sounds best to your ears.

 

[Steamthief]

I swapped out the stock Sovteks in my TB-600 with some used, 100% tested Telefunkens and the difference was dramatic to my ears. Hi-mids and highs are sooooo much smoother, and I even got a little hotter output.

That being said, I've read that rolling preamp tubes depends on the preamp itself - some amps don't benefit much from it, others do. For brand new tubes, I've heard nothing but good things regarding Tung-Sols.

 

[cellkirk74]

I like this one in my preamp:
JJ ECC803S / 12AX7

 

[ivbenaplayin]

I like this one in my preamp:
JJ ECC803S / 12AX7

I took it apart last night and pulled the tube - that's what they had in it from the factory, and it was indeed smoked... I've decided to order a few different ones (EH gold, Tung-Sol, Tesla, and Groove Tubes) and play around with it to see what happens... I really don't anticipate much difference since A.) it's a single tube preamp, and B.) the EQ on my new Bongo freakin' kicks b-a$$!

 

[Thornton Davis]

I've decided to order a few different ones (EH gold, Tung-Sol, Tesla, and Groove Tubes) and play around with it to see what happens... I really don't anticipate much difference since A.) it's a single tube preamp, and B.) the EQ on my new Bongo freakin' kicks b-a$$!

I'd be interested in hearing your comments. I've been considering switching the 12AX7 Rudy in my amp to a E-H Gold or Tung-Sol.

TD

 

[ivbenaplayin]

I'd be interested in hearing your comments. I've been considering switching the 12AX7 Rudy in my amp to a E-H Gold or Tung-Sol.

TD

I'll let you know what I find...

 

[DJBenzBass]

From constant tube swapping in many different preamps, my 2 favorite are the JJ ECC803S Hi-Gain & Tung Sol gold pin. Now I see the JJ ECC803S Hi-Gain comes in a gold pin version as well. May have to get a few.
Good luck in your search!

 

[Jim C]

I have had an SM400 for many years (probably 20) and only keep it as a backup as the resale is terrible even those are good amps

Spent a lot of time rolling tubes in this amp and have found that it didn't make that much difference between: Groove Tubes, Sovtec, NOS GE, NOS RCA

The only tube that made much difference IMO was a used Mullard
Have heard from others I trust that a Telefunken tube works well
Not sure how the reissue Mullards compare to the originals

BTW, Mullard made tubes for a lot of other manufacturers and they seem to last forever; mine was marked Eico / Mullard and was pulled from an old Hi-fi mono preamp

 

[Rano Bass]

I used to own an old swr redhead and i used a groove tubes with good results.

 

[GHWelles]

I like the JJ high gain and the China 12AX7
I tried a couple Amperex bugle boys and they are bright and clear but don't seem to compress as well with distortion.

 

[Cblues]

I owned a SM-400 and experimented with different preamp tubes, including an expensive NOS Mullard. The conclusion I reached after trying 6 or 7 different tubes is that for live rock gigs an expensive preamp makes little difference to what you hear on stage or what anyone else in the venue hears.

How very true...I use an sm400 or a SWR Grand Prix and a Crown mostly...For the loud rock gigs no including myself will notice the dif tonal values etc of the expensive tube in the preamp.

 

[Jim C]

Just as a clarification, IMO SWR's are not that sensitive to preamp tube brands.
OTOH, a Mesa Walkabout is very sensitive and changing preamp tubes abosultely changes the tonality of the amp (OK not huge but definitely audible in a band situation)