mesa sp12ax7 tube?

[TheNightLife]

does anyone have any experience with this tube? from what im seeing its a high grade substitute for a 12ax7 (ecc 83). im thinking about putting this tube in my preamp section as tube one of my svt-cl. any thoughts or recommendations?

[Scutterflux]

find out what sovtek version it is, and save yourself some money, probably the LPS if it's supposed to be good. I think Mesa tubes are relabeled Sovteks???

[beans-on-toast]

It is a tube that has been screened for low noise and microphonics. It will work in the first pre-amp tube position (V1) of any amp, including the CL, that takes a 12AX7.

I've had SP12AX7's that came in a couple of Boogie amps that I've owned. I found that they worked well. Having a low noise tube in the V1 location in any amp is a good thing.

There are a number of low noise 12AX7 options available. For example, the 7025 and ECC803S are both NOS low noise tubes. There are others to look for, search for "low noise 12AX7". Some do a much better job than others. The better ones like the ECC803S can be very expensive.

Finding a good tube that meets your expectations can be difficult. In this case, they are pre screening and selecting a quiet tube for you for a slightly higher cost.

[coreyfyfe]

Originally Posted by Scutterflux

find out what sovtek version it is, and save yourself some money, probably the LPS if it's supposed to be good. I think Mesa tubes are relabeled Sovteks???

They use a variety of tubes (russian, chinese, etc) from what I've read, but given that this is supposed to be "special" and low noise, it's probably one of the better russian tubes. The sovtek 12ax7LPS as mentioned above is supposed to be pretty good, it's a long plate tube with a special construction that's supposed to help reduce microphonics normally associated with long plate tubes. I have one, wasn't bad in my SVT when it was set up for 12ac7s, but I preferred the NOS tubes I had. Either way, there are lots of good sounding tubes out there that cost less than the $21 that mesa charges for their special 12ax7.

[TheNightLife]

well the thing is i work for guitar center and we have that tube here so for me its only 7 bucks lol

[coreyfyfe]

Try the mullard reissues. GC carries those as well. They're sovteks, but they're rated pretty decently. I tried one the mullard reissues in my SVT-CL when I had it, it sounded pretty good. At least better than the stock sovtek that it came with.

http://thetubestore.com/12ax7review.html

[TheNightLife]

Originally Posted by coreyfyfe

Try the mullard reissues. GC carries those as well. They're sovteks, but they're rated pretty decently. I tried one the mullard reissues in my SVT-CL when I had it, it sounded pretty good. At least better than the stock sovtek that it came with.

http://thetubestore.com/12ax7review.html

see the thing is im looking for something thats gonna be a little cleaner then the stock stuff in it now. the mullards id have to order which id rather not do lol i think im gonna give the mesa sp12ax7 a shot

[beans-on-toast]

For a cleaner sound, try a lower gain tube like a 12AY7 or the low noise version of the 12AY7, the 6072.

[paganjack]

the mesa sp12ax7s are decent tubes. The "special use" moniker just means that it tested above a certain standard on the tube tester. Ostensibly there will be less variability in their sp12ax7s, but it's not like they are specifically made differently.

For $7, go for it.

[nervous]

Sorry to drag up an old thread but can anyone tell me about the wrapper As seen in the pic below) on these tubes? I assume it is meant to be left on and not removed before use?



First time I have ever seen this.

[B-string]

It should be a hi-temp silicone damper, meant to be left on (fights microphonics).

[JimmyM]

Originally Posted by B-string

It should be a hi-temp silicone damper, meant to be left on (fights microphonics).

Really? First I've seen that. I figured it was a wrapper just to keep fingerprints off the glass.

[B-string]

Originally Posted by JimmyM

Really? First I've seen that. I figured it was a wrapper just to keep fingerprints off the glass.

There is a company the sells reusable dampers call "FatHeads" IIRC. They look like a halo. They will reduce some audible microphonics. Old school was to use a hi temp "O" ring on the base but the socket tension had to be really good.
FatHeads is no longer around? Can't find them anywhere.

Here is a high priced version (marketing boys can really make it sound like the end all). http://www.tubedepot.com/dctuberings.html

[nervous]

Originally Posted by JimmyM

Really? First I've seen that. I figured it was a wrapper just to keep fingerprints off the glass.

Yup, that's what I was originally thinking as well, or possibly a shipping sleeve of some sort but this is really on there and I think if I had tried to take it off I would have risked damaging or at the bare minimum scratching the tube, all far worse outcomes than some fingerprints (which, BTW, I have read are inconsequential to these tubes unlike halogen bulbs, because they just don't get hot enough to matter. But, that's another topic). Glad to have confirmation that it's meant to be there. Thanks.

[B-string]

Originally Posted by nervous

Yup, that's what I was originally thinking as well, or possibly a shipping sleeve of some sort but this is really on there and I think if I had tried to take it off I would have risked damaging or at the bare minimum scratching the tube, all far worse outcomes than some fingerprints (which, BTW, I have read are inconsequential to these tubes unlike halogen bulbs, because they just don't get hot enough to matter. But, that's another topic). Glad to have confirmation that it's meant to be there. Thanks.

People have tried many ways to deal with microphonic tubes, other than dumping them.
I just saw recently someone is using leaded glass on some output tubes ! Don't handle those with bare hands, I would bet finger oil will degrade the glass.

[nervous]

Here's a little up close and personal for those who have not seen the insulator we're talking about:

[JMac4strngr]

From what I can tell, It looks like common heat shrink tubing.(?) Be cool to know if it is... If that is the case, that stuff can be found at any electrical supply house and some home improvement stores. It is available in pre-cut lengths or on a roll. You'd basically buy the next size up in diameter, cut to desired length, and heat shrink it with a heat gun.

[Doufuss]

I bought one of these for my kid's M9 Carbine. It mightily reduced the amount of hiss that these amps are famous for and you can crank the gain a lot further before it breaks up. At 2:00 pm you get a noticeable amount of nice smooth tube compression with just a little fur. This is the older model, with one fan and no grill in the top.

Of course, your mileage may vary. But my experience has been a very pleasant surprise.

[beans-on-toast]

It is a heat shrink cover over the tube but it is much thicker and harder than the standard cable heat shrink tubing.

I think that it acts as a damper to some extent. It would make sense if it had some sort of heat sinking and EM shielding capability build into the material. Both these features would benefit the tube. Like a build in metal tube shield.

It's also provides Mesa with a bit of a marketing advantage. You can't see what's inside the glass envelope so they can change the tube to whatever is currently available and still label it as a STR SPAX7-A. You never know what you are getting. They will meet the same spec. In reality, some tubes are going to exceed that spec more than others and therefore perform even better. In the past when they were available in larger quantities Mesa used american made NOS tubes and the quality was very high.

[Bongolation]

Originally Posted by beans-on-toast

Having a low noise tube in the V1 location in any amp is a good thing.

I'll say.