(SED) Winged "C" 12AX7

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cesjr

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I love the SED 6L6's so much that I'm now interested to try their 12AX7's in my Mark IV. At the tubedepot.com they have a few options; high gain, low noise, balanced triodes etc.

My question is what option would work best in each tube position? Balanced triode in the phase inverter, low noise and microphonics in the input stage? What about high gain rated tubes? Are they worth the extra noise?
 
According to Mesa you won't need a balanced Phase Inverter because of the design of the amp. They don't believe in Matched Phase Inverters like other brands.
 
I like older tubes in V1. I have tried 60's GE, RCA and Mullard. I like the RCA and GE better in the Mark IV. I liked the Mullard but they do more for my Marshall so there they will stay. I have had EH and JAN Phillips. Both sounded ok. I think you really need to try them all. It is good to have a good selection when you are tone searching anyway. I think Boogiebabies said he likes the GT12ax7m in V1 and V5 with the GT12ax7C9 in V2-V4. I like the C9 but not as a V1 either. Though it does sound ok in the 800. I have an R2 that I have tried in the Mark IV and it sounds decent but nothing spectacular. In the JMP it sounds great but doesn't do what a Mullard can. If you have a bunch of different ones you can mix and match to find your tone. I am often swapping still just to try to get the tone to die for. I think I am almost there with the JMP but I am just lacking some nice xf2s. The 800 likes most tubes but some can make it really happy. As far as the Mark IV goes, all I can say is I am still working on it but have found old tubes to sound better than the current production stuff. BTW try to stay clear of the SPAX7. It is not that premium of a premium tube. Sure it may be screened for microphonics (as all tubes should be anyway) and noise ( a good tube will not be noisy either) but it is far from screened for life expectancy or even (across both triodes) strength. I tested a bunch of them to find a mixed bag of half dead tubes that sounded ok but I can't have any faith in them lasting very long. Out of a half dozen I got one that I would consider decent and it barely passed as new on both triodes on my tube tester but still wasn't very matched. I am leaning towards GT for my future current production purchases. High gain tubes do give more noise but as you get more gain you get more noise. It is a simple trade off. If you get older tubes you can get higher gain and still have nice tonal characteristics that are different amongst the old manufacturers and more often than not you will have less noise than current high gain tubes. If you pay a little more for your current production tubes you can have them hand selected by those that screen them for their buyers. I still think that GT is probably the safest bet in the new tube market even with the SAG high gain kits. You just seem to get more for your money though you'll also spend more than if you had bought Mesa preamp tubes. Also be aware that Ei tubes can be flaky. It is suggested to only buy the higher end Ei's from reputable dealers with return policies for microphonic tubes as microphonics seems to be their weak link. The popular consensus is that the JJs tend to take away from the sparkliness but do high gain very well. I do know that Sovteks tend to be rather generic and lifeless unless you get a nice LPS. I have had Svetlanas in the past and they were ok but nothing spectacular. Telefunken and Amperex are nice choices. Brimar and Mullard are very nice too. RFT, Mazda, Tesla, and Phillips were nice tubes also. Actually Sylvania made some really nice tubes. Tungsram was another to consider. Any of these tubes will make a difference in V1. Some swear by EH, but I didn't see the attraction when compared to older tubes. Your tone is something that you will be the only one to decide what you like. Sure it might get expensive but once you figure out what you like it is easy and you have spares and different flavors to play with in the long run. My suggestion is try them individually not 5 at a time and see how you like them in each position. If you like a particular tube buy another and try different combinations until you get it completely right for you. Just like the power tubes the tone will vary with each different tube you put in there. I decided that the SPAX7s that I bought will just be emergency spares because if they get banged around a little it won't be such a loss if one breaks. I will leave my tube caddy at home and only ever take a couple well packaged if I want to experiment elsewhere. I am sorry but I don't know about the SED offering.
 
According to Mesa you won't need a balanced Phase Inverter because of the design of the amp. They don't believe in Matched Phase Inverters like other brands.
sometimes agree, sometimes disagree. mesa/boogie manufacturer the phase inverters with a non symetrical phase split, to achieve a classical rough and rude sound, so if you likes that tone you don´t need a balanced tube but if you like a cleaner sound so get a balanced tube, of course you will achieve the cleanest sounds modding the phase inverter stage with a pure symetrical split.
This asymetrical issue is a far cousin of the asymetrical clipping in most of the distort stompboxes
 
I really appreciate the replies. But I guess the SED 12AX7's are currently out of production. Anyone else hear this? I was really interested in trying them but I can't find a dealer who has any left in stock.
 
No problem with outstock, I have half a dozen of "C" 12ax7 tubes ;)
They aren´t outstock they are still manufactured.
Long time ago sovtek buys the svetlana brand and begin to manufacturer them in the sovtek factory labeling them as svetlana.
The old s.Petersbourg factory where old svetlanas were born still manufacturer the old svetlanas but labeling them as "C" ( the "c" cyrilic letter is the "s" occidental letter of svetlana )
so don´t be afraid we will have "c" tubes for many years.
Refers to "tubetown" or "tube amp doctor " both of them have the "C" 12ax7 tubes.
 
Well that's good news they're still being manufactured. I must have received some false information.

Does tubetown or tube amp doctor ship to the states?
 
I can't seem to find a US distributor who carry SED 12AX7's. They simply don't stock them anymore. Any reason why? I also hear a lot of mixed reviews. People either love them or hate them.

I still haven't heard back from tube town on whether they ship to the states.
 
A guy at Tube depot told me they're not being produced anymore. So maybe you and a few others are buying what's left? They don't seem available in the States.

I also remember reading (a rumor) that the SED 12AX7's are going under a redesign because they're "not reliable."

Also I just received word from our friends at the tube store saying, "We offered them years ago for about one month. We dropped them quickly because we found out that they pretty much don't work in guitar amps because they need DC heater supply or else they hum badly. Very few guitar amps have DC heaters so it made no sense to carry it as 99% of 12AX7 users are guitar preamps."

:?
 
hey welcome to the marvelous urban legends where everybody hears and talks of things without any knowledge.
i´m still buying the sed 12ax7 with no troubles, maybe on a few years they will be out of stock, ok no problem then my tubes will be nos and I will be as rich as arabian petroleum, i will buy a mansion in manhattan ;)
 
So what about "the need DC heater supply…" Or something about not recommended for use in amplifiers with "AC filaments."

This all speaks like a foreign language to me but is a concern none the less. By the way fatboy135, what amplifier do you use them in? Any problems with the "elusive" hum?
 
I never hear nothing about special filament purposes tubes :shock:
I think that a tube is only a tube it is not something special or voodo magic that a tube is build only to be used on a special feed ad or dc circuit :?
for example on my triaxis the filaments supply is a +/-3.2 AC volts ( 3.3 volts of amplitud so 6.4 volts peak to peak ) and I have the "c" on the 5th position and it is so fucking good for me.
Theory said to us to try to avoid the AC voltage the maximun as we can do it, because the 50,60 cycle hum could be induced by the filaments.
But dude, believe me my triaxis uses AC power for the tubes and the "C" is the cleanest tube on my setup, no hum, even there are so many triaxis users that wants my setup because it is funny silence, I don´t know why because I never mod any part of the circuit to get a silencer but comparing it with another triaxis of my friends they are very surprised it only has background noise on the ld2 yellow and ld2 red, even the ld1 red that is plenty of gain is farest from any noise. Think that I only use the hush gate from my intellifex on presets with ld2 yellow or red modes.
 
fatboy135, the curiosity has gotten the best of me so I think I'm going to order from Tube town.com.

My question for you is should I go with their sed12ax7 or sed12ax7-a? Would it be best to put their “audio selected” tube in the first gain stage only?

Thanks
 
Thanks for all the information, I ordered some this afternoon. I can't wait to try them. :D
 
After long anticipation my SED 12AX7's arrived from Germany (tube-town.) The wait was well worth it, I'm really happy with these tubes. Out of the six tubes I purchased only one was microphonic, most likely due to shipping. I can't really describe the tonal differences between these and the Sovtek 12AX7's. But in my opinion they sound much better. I still have to swap these around trying to find the best spot for each, but other then that they sound great.
 
Fatboy135, thanks for the push to try these tubes. I couldn't be more pleased. I did decide to order a single prescreened (low noise) tube for V1 in hopes of lowering the noise a little, but in general these are very quiet tubes.

Not to mention great tone :D
 
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