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12at7 rolling

B

Br1ck

Super Member
Well, time to roll some tubes in my new Stereomour 2A3 amp. I went into my tube stash and pulled out the following:

Amperex 12at7 made in Gt Britain
Raytheon 12at7wa made in USA
Telefunken 12at7 made in West Germany
TEN 12at7 no country Japan? tell me guys...never seen one
IEC Mullard 12at7 made in Gt Britain
Westinghouse reliatron 12at7 made in USA
Amperex Bugle Boy 12at7 made in Germany
Raytheon registered 12at7 made in Japan

What goes in first?

Tube that came in kit to worn to tell. letter A in a box and USA is all the markings I could read.

Ok, the Tele went first. I can see why many would think this the best.
 
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Ha, running the Bugle Boy now and you may be right. Very close to the Tele.
Mullard not the tube for this circuit.

Testing with Mozart all day. What a genius he was.

Maybe I'll go on a Coltrane or Art Blakey binge tonight.
 
you are correct at7s is what I'm rolling. Corrected.

Actually, the Amperex made in Gr Britain that look identical to the Mullard seem to have more clarity. Am I imagining things? I'm just trying to get my head around who made what for who.
 
I rolled in a pair of RCA black plates and liked them better than the teles that were in there. This was in a preamp. You gotta try 'em all because you never know.
 
The Westinghouse 12AT7????? how are those compared to the GE winged plates??? I have some of the winged-plates to be honest they really scream haha. The GE 5751 Bp tripple Mica would smoke that whole list though haha.
 
The 6201 is a step up (IMO) drop in. Here's a couple nice Mullards, but all the Euro companies made them.
 

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Ok, I'm getting confused. Can I assume if a tube looks identical in every detail, it was made in the same factory? I have three tubes, Mullard, IEC mullard and an Amperex made in Gr Britain that look identical. Are they all the same? My brain and ears are starting to play tricks as the Amperex made in Gr Britain seem to be brighter than the other two.

Anyway, I'm getting an education. I'll look for a 6201 in the stash.
 
Br1ck said:
Ok, I'm getting confused. Can I assume if a tube looks identical in every detail, it was made in the same factory? I have three tubes, Mullard, IEC mullard and an Amperex made in Gr Britain that look identical. Are they all the same? My brain and ears are starting to play tricks as the Amperex made in Gr Britain seem to be brighter than the other two.

Anyway, I'm getting an education. I'll look for a 6201 in the stash.
Click to expand...

If you go over every single detail inside and out, and they are exactly the same, I think you can safely assume they came from the same place. You have to look closely though, and preferably with magnification unless you're 20 years old. :D
 
OK, out comes my visor magnifier for a closer look see. The Raytheon 12at7wa also was marked 6201, so I do have one. It is pretty sweet. I'm trying to hone in on the tube that captures the best balance of warmth and high end detail.

So far the advancing to round two are the Tele, Amperex made in W Germany, the Bugle Boy, the Westinghouse made in USA (Sylvania made?), and the 6201.

My first criteria is is the overall sound lush and engaging? I guess you could call this mid range. Then I hone in on highs and realistic bass. Is there woody tone to acoustic bass? Anything harsh doesn't make it.

My pre has six tubes in it already, so leaning to a neutral and detailed power amp front end, which is why the Mullards don't work here. I'll try more rolling in the pre at a later date. I have JJ goldpins in that one mostly with an RCA blackplate if I remember.
 
It would seem to Me Too, in a PreAmp...RCA Black Black Plates are the Way to Go...They are both Neutral and Dynamic & Quiet...
 
I had a number of 12AT7s but have been thinning the flock. My only use for this tube is in the phono stage of my Conrad Johnson PV10A preamp, and I don't have that (stage) tubed at present, as I haven't had a turntable hooked up for about 3 years now. Will get to that soon.

I'm down to just 3 of them: Telefunken, Mullard CV4024, and GE 5-Star. Don't even know which is my favorite. These three were the best in my test for low noise and microphonics.
 
I bet those Amperex AT7s are really nice. I have a few of the world Logo 12AU7s they are really nice but 12AU7s just take too much away from everything in my opinion, 12BH7 sounds much better. I need try a good Raytheon too.
 
Br1ck said:
My pre has six tubes in it already
Click to expand...

I have to wonder why you would consider using a preamp, particularly one with 6 tubes. You have 2VRMS coming out of your CD player or phono stage and the Stereomour can be driven to clipping with .4VRMS input. So you have 2V into your preamp; you knock that down to millivolts with your volume control so you can amplify it by your 6 tubes despite the fact that you can never output more than .4V!

You will never get the full appreciation of the Stereomour with a preamp. The whole idea is to have only 2 stages of amplification and no cables and connections to add distortion and muddy the sound.
 
Are you suggesting I would be better off bi passing the line stage ? I do have the same phono pre as a stand alone unit. I don't use CDs. I'm vinyl and streaming only. I do need the multiple inputs, but Bottlehead has a fix for that.
 
Less is more. Interesting. Just the phono pre is plenty. I'm going to need a line stage for the computer, but the Stereomour has three inputs for a reason, I guess. Thanks for the tip. I learn something new here every day. Better to run the Stereomour at 75% gain than 30%.

Might change my AT7 prefrence. The Bugle Boy sounds pretty darn good.
 
Br1ck said:
Are you suggesting I would be better off bi passing the line stage ?
Click to expand...

I am suggesting that you plug your source, whatever it is, directly into the Stereomour. The Stereomour will be driven to clipping with only .4V input! The standardized output voltage from any source is 2V and that includes the sound card in your computer. That's why there is a volume control on the Stereomour.
 
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