Need Help withTube Selection

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Jim McNealon
Posts: 48
Joined: 27 Sep 2000 12:01 am
Location: Tampa, FL, usa

Need Help withTube Selection

Post by Jim McNealon »

I need to retube my 67' Twin. Are there any brands that are better than others? Are there any gourmet brands available? I figure that I'm not going to have to buy tubes very often so I dont mind spending a little more to get optimum performance.
I have found a tube dealer that has a kit for Twins. It consists of (4) 12AX7 Yugo made Phillips, (2) 12AT7WC US Phillips ECG JAN Tubes, (4) 6L6GC matched Svetlana Tubes.
The chart on the side of the cabinet calls for (3) 7025, the kit has apparently substituted 12AX7 for the 7025.
Are 7025's discontinued or is this an upgrade?
Thanks in advance for your opinions...Jim
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Scott Swartz
Posts: 1079
Joined: 23 Jan 2001 1:01 am
Location: St. Louis, MO

Post by Scott Swartz »

7025 refers to a 12AX7 that was guaranteed to a low noise or hum spec in the old days, the gain and performance parameters are exactly the same as a 12AX7.

Yugo 12AX7s can sounds pretty good but tend to go microphonic. NOS RCAs or GEs would be better, but cost WAY more, and even these can be microphonic. If you buy NOS at the going rate of $30 each, make sure they are guaranteed.

The phillips 12AT7s aren't too bad.

The Svetlana 6L6s sound pretty good but often times require a different (higher negative voltage) bias point. You will want to get the amp rebiased if you buy this kit.

Here are a couple of sources for good US made NOS tubes
www.tubesandmore.com (Antique Electronic Supply)
www.angela.com (Angela Instruments)
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Ricky Littleton
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Joined: 7 Mar 1999 1:01 am
Location: Steely-Eyed Missile Man from Cocoa Beach, Florida USA

Post by Ricky Littleton »

You are well advised to steer clear of the Yugoslavian tubes. NOS RCA, Tungsol, Phillips, Mullard and the such are good choices. In applications such as the paraphase amp section of your amp, the 12AT7 is a good choice, but all other preamp tubes should be the 12AX7 or it's variants. ECC83's, 7025's are excellent choices depending on where you want to get to for sound and tone.

Sovtek is a good brand of tube thatg is "middle-of-the-road" in price. Groove Tubes are pretty pricy, but they are precision matched differently than other matched power sets and it shows in their tone.

You can call me at my shop toll free at 1-866-379-0000 if you want to talk more about tubes.

Good luck

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