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#24648 by Shredd6
Fri Mar 07, 2008 9:01 am
Wow man... I just got a tube in from ebay that freakin blew me away..

All week I've been buying and experimenting with tubes for my amps. I ran a test of 7 new (and NOS) 12ax7 preamp tubes.
It's been really interesting to go through the sales pitches and reviews of sellers, buyers, guitar geeks, and ham radio geeks (and I use the word geek as pros). I've looked at test charts. 1200/1800, 45/36, 86/92. 2117354/987997, 47873648/908734064. On their Hickocs and Eico's and every tube sounds great, and you just can't live without their brand. Russian, American, Chinese, Brittish, Military stock, medical stock, NOS, NIB, Octagon letters, unlabeled, sourced out, Triple micas, black plates, curved black plates, grey ribbed plates, Cryoset, D getters, O getters, Halo getters, tilted square getters, pu**y getters !!!!! AAAGGGH!!! I just gotta hear it for myself!!!

I mean, HOW MUCH DIFFERENCE CAN IT MAKE!!! Some go for $12, some go for $50, $100, $500.. Obviously I can't buy them all.. I'm just a blue collar guy with a tax return. I just bought 10-12ax7's, 4-5u4's, 4-6l6's, and a 12bz7 and I still ain't done..

But tonight I tested these 12ax7's with my own ears, through my Marshall Valvestate which only takes one. I picked these tubes based on the evaluations, reviews, and sales pitches of all sorts of people and their tests, some close friends, some strangers, and 3 results were really surprizing to me.

First let me show you how I rated them in my opinion. But before I do, I want it to be known that I don't have the money for Genalex, or Telefunken's, or other extremely expensive tubes. And I tested these tubes in distortion only. Generally I've found that if a tube sounds vibrant when distorted, you'll be fine with it in clean channel.

This is how I stacked 'em up after switching 'em up bracket style.. Head to head as well as process of elimination. It literally took me a couple of hours to do this with 7 tubes. But it was definitely worth it.

1. RCA- nos
t2. Mesa
t2. National-nos
3. Sovtek- LPS (cryoset)
4. Groove tubes
5. Sovtek- WA
6. Tungsol

Ok.. So lets get to the ones that didn't surprise me first.. The National Union, the GT, and The Sovetek-WA didn't surprise me.. The WA comes stock in a lot of stuff, and the GT is pumped HARD by Guitar Center for the masses. Both sounded flat and without any vibrance to me. But I knew the National would test high. The Sovtek "cryoset".. Ok let's move on. It was just middle of the road.

Now the surprises..

This is a three way tie in different ways.

The Mesa was really surprising.. It was arguably the best value 12ax7 of the bunch. I was told that these were heavy on the bass side, "not too bright, not so colorful".. Complete BS!! This tube hung with both NOS tubes in straight-up balls and sound-color. I couldn't tell the difference between the Mesa and the National. I bought it for $16 at Guitar Center, and it was a total baddass.. Screw GT. This is a stock tube with a NOS sound, and that's why I listed it just above the National. Phenominal result for the price..

The Tungsol.. What a total POS!! The output was 1/2 of the others, flat, not even worth being in the test. And if anyone wants to say "maybe you got "2" bad tubes", then I would say to Tungsol, "be more consistent. I could accept 1 out of 2 being bad, but not 2 out of 2. They suck. Period. Both of your tubes went right in the trash right along with my $25 bucks, I'll never buy your crap again."

The best tube by far was the RCA-nos.. MY GODDD!!! I knew it would be good, but not this good. This is heaven in a 1" glass tube. My jaw dropped to the floor and I just stood there staring at my amp for the next 5-minutes... I always wondered why some people swore by NOS tubes, and now I know by my own ears. Most people would've stopped at just this tube, but I spent the next couple of hours evaluating 2nd, 3rd, and so on.. It wasn't even a close second. The National and the Mesa were miles behind, and I bought this tube for $50 just to see for myself if the myth was true.

It kinda sucks because I spent the money on sales pitches and charts, and reviews, and Hickock readings, recommendations from friends and peers, and a ton of crap.. But sometimes you just need to listen with your own ears without all the explanations you read. I can now only imagine what the Genalex and Telefunken tubes sound like. If they are really miles above this RCA, I would probably go into a coma!!

Anyway.. That's my geek review. Take it or leave it. Make of it what you want.


#24666 by Chris2203
Fri Mar 07, 2008 2:21 pm
Great Read - I love "field testing" posts!

#24670 by jw123
Fri Mar 07, 2008 2:52 pm
Thanks, I use Mesas in my Mesa. A couple of years ago I did what you did and tryed a variety. I dont think I tryed the RCA NOS, maybe I should and see how it works.

Thanks for sharing.

#24741 by Shredd6
Sat Mar 08, 2008 12:22 pm
I just ran across a tube place that will sell you customized setups for amps like Mesas that have a lot of tubes. But after seeing the list of tubes they use in their kits, it looks like a BS service to me.

Here's a list of the 12ax7's in a "custom kit" for a Triple Rec.

(1) Tung Sol 12ax7
(1) High Gain JJ
(1) Penta 12ax7
(1) Shuguang 12ax7 9th gen.
(1) Sovtek LPS 12ax7

I haven't heard the JJ, but I guarantee you it's nothing like an RCA.
The Sovtek isn't bad, but it wasn't anything special.
Shuguang's and Pentas aren't generally known to be better than the Sovtek.
And you know how I feel about Tung Sol.. They must be the most brittle of the bunch, cause mine were DOA.

So basically, they're putting the JJ in the #1 slot, and everything else is middle of the road or stock mass produced tubes that are marked up 50%. And 1 POS.

Along with the marked up price of the tubes, they want $150 to install the tubes!!! And Mesas are "fixed bias" amps. So basically, they're charging you $150 to change 11 light-bulbs..

Normally I would say to myself "what a bunch of A-holes".. But if someone is willing to fall for it, and they don't do their research, and they have it done and are happy with it.. Then I guess all power to the tube place. They gotta move that stuff and make a buck somehow. The installation fee is a little dishonest though. Not cool.

#24748 by gbheil
Sat Mar 08, 2008 2:19 pm
Its scary to me how much I have too learn in this business. Im so used to being at the top of my game in my other endevors. Just goes to show humility is a good policy.

#24749 by HowlinJ
Sat Mar 08, 2008 2:31 pm
Every body's out to make a buck for sure. Doesn't matter if it's someone stickin' a tube in your Boogie, or a mad Strat thrasher blowin' the cobwebs off the rafters down at the local beer joint. remember what ol' P.T.Barnum said about a sucker being born every minute. It's just part of the "down-side of Capitalism" , wouldn't wanna' have it any other way!

I have always been an advocate of vacuum tube guitar amplifiers. It's virtually the only application for tubes (or "valves", if you prefer) in this day and age. As long as you guitar players keep demanding them, there will be a supply. Otherwise the market will naturally "dry up". I'm not convinced that those little 12ax7 preamp tubes have any perceivable audio effect on an amplifier's output. The real engine in your amp are those 6L6 "power" tubes.
All tubes must be replaced eventually, but when you replace them, it's somewhat like getting a brand new amp , sound-wise. Rock On guitar playin' brothers and sisters, and for the sake of all of us , KEEP BUYIN" THOSE TUBES! ...

#24798 by Shredd6
Sat Mar 08, 2008 10:15 pm
I have to have at least one tube in an amp.. A true Solid state is only good for practice amps in my opinion.

But in all honesty, those little 12ax7's mean a whole lot to your sound. The difference between a NOS 12ax7 and a modern 12ax7 is like putting 87 octane in your car vs. putting 92 or higher.

The distortion that comes with your amp will be clarified and perform and sound better. It's amazing what those tiny little suckers can do..

I'm about to fire up my Rec right now.

This is how I set up my preamp tubes:

#1- RCA
#2- Mesa
#3- National
#4 & #5 Sovtek

I just bought a matched quad of SED (winged C) 6l6 tubes, and some Mesa Rectifier 5u4gb's.. I'm waiting on a 12ax7 Brimar-nos, a Sylvainia-nos, and some SED 5u4's, but in the meantime I'm gonna see how this sounds.

Wish me luck..

#24866 by Starfish Scott
Sun Mar 09, 2008 3:15 pm
I have RCA 6550's in my Marshall 100W JCM 800. It's what it came with when I bought it.

I think the last owner upgraded them, but to be honest I don't really know. And I am dreading having to replace them and rebias the new tubes for the head.

(My buddy uses Sovtek tubes and I don't like them at all)

#24874 by jw123
Sun Mar 09, 2008 5:59 pm
My old Sunn head still has Sylvania 6550s in it. Capt 4 6550s are the equivalent of 180-200 watts. Thats what an amp tech told me a few years ago. So that Marshall is one bad puppy with all that fire power. I got out my old Sunn head and played a couple of days ago. I have an old powersoak that I attenuate to -32 dbs and it is still loud. The old tube SVT amps had 6 6550 tubes in them. Ive always been curious if I could put EL 34s in my old Sunn head.

#24892 by Shredd6
Sun Mar 09, 2008 10:17 pm
Captain Scott wrote:I have RCA 6550's in my Marshall 100W JCM 800. It's what it came with when I bought it.

I think the last owner upgraded them, but to be honest I don't really know. And I am dreading having to replace them and rebias the new tubes for the head.

(My buddy uses Sovtek tubes and I don't like them at all)

That's a fat setup. To replace 'em with the same would run about $300-$350.

You should have them tested before you replace them, you'd be surprised how long NOS tubes are said to last. (My guess is, that's why they don't make 'em like that anymore.)

How do those Sylvania's sound?? They're supposed to be just as good as RCA's.

I don't think you can replace your 6550's with el34's.
Looks like the replacement for your 6550's are KT88's, which if you ask me are much better than el34's anyway. They're short, fat, Coke-bottles. If you're used to hearing your 6550's, you'll probably feel like you downgraded your amp if you put in el34's. I tried it once on my Rec, and took them back. But then again, I'm not a soloist.

By the way I finally have a lineup for my 12ax7 preamp design.

12ax7 (5):
#1 RCA-nos (1950's)*
#2 GE (5751 triple mica)-nos (1950's)
#3 GE (5751 triple mica)-nos (1950's)
#4 Westinghouse/RCA- nos (1960's)
#5 National- nos (1960's)

*Depending on how good the GE's sound, I might move them to the 1 and 2 slot. The triple mica design is said to be Ultra quiet, High gain.

This thing is gonna sound like a freakin freight-train!!!


#24957 by Starfish Scott
Mon Mar 10, 2008 4:29 pm
Good God, I wondered why they lasted so long. (I have had this head for 4 years now, never had to change even (gulp) 1 tube)

I noticed that the head had a very warm, brown sound but I never had a marshal head before this so I assumed that it was just the head.

Now all I need is to get a quality power soak so my ears will stop bleeding.

#24971 by Starfish Scott
Mon Mar 10, 2008 7:49 pm
OOf, so I was checking everything out and I made some mistakes..

My Marshal head is a JCM 800 Mk II Super Lead 100W/ with 4 inputs and no master volume.

It has 4 smaller tubes in aluminum (12ax7's?), 3 6550's (found out to be Tung-sol) and 1 HUGE rectifier tube (unknown).

My amp guy was looking at it closely and he thinks it's 50's? (I think he is wrong, wrong, wrong)

He offered me 5k for it cash. I told him "no way." (It'd be like selling a child and I probably would sell a child before that head)

I thought it was a 1979, right on the edge before they changed them complete with selenium rectifier. Now I don't know. I know my amp guy knows more than he is telling, but that's all I know.

I thought that sucker was supposed to have 4 smaller tubes and 4 matching larger tubes (el34's or 6550's). Seeing the 1 rectifier tube that was 2x the size of a 6550 was a shock to my system. I would love to know why that was done and is it a mod??!!??!?!?!?!?!?!?!??!?!!?!!?!?????

#24994 by Shredd6
Mon Mar 10, 2008 9:14 pm
Damn dude.. That's crazy!!

You might want to try asking here.

At least you might get an honest answer. You might be sitting on a goldmine..

( How much you wanna bet Capt. is polishing his amp right now. Cleaning it up. Got the Armorall out. Big smile on his face. Haha )

#25007 by HowlinJ
Mon Mar 10, 2008 10:31 pm
HaHa,I sold my black panal" Fender Super Reverb Amp" to Ceasar Diez for a hundred bucks! Foolish, wasen't he? :wink: ........................... :oops:

#25008 by HowlinJ
Mon Mar 10, 2008 10:33 pm
Ha Ha, I sold my black panel"Fender Super Reverb Amp" to Cesar Diaz for a hundred bucks! Foolish, wasn't he? :wink: ........................... :oops:

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