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Favourite 6FQ7's





PHOTO: The RCA black plate D-getter "chrome top" 6CG7 which is my favourite for 6FQ7 positions





PHOTO: The odd "Omega" labeled black plate, Square getter 6CG7's that were made by Hitachi.


Ivan303,

My favourite 6FQ7 is the 6CG7.

In all my gear- which use 132 tubes of 31 types, I use only 4- 6FQ7s, those in the Audio Research D115 power amplifier.

When I bought the D115 in 1985, there were no 6FQ7's in production so years later when it was easy to buy NOS, obsolete types on Ebay I decided to have an over-selection that I could later cull to the model I liked. this resulted in buying 51! At first I bought 6FQ7's, but when I read of the original design for the reduced 6SN7 - the 6CG7 with the centre electrostatic shield- I liked that idea more. More is more!

My theory was that when they squeezed the big 6SN7 plates into the more compact 6CG7 bottle they must've felt the need to have the shield between. This shield was grounded to pin 9 and therefore if the amplifier had that pin to ground, you've quell the cross talk between the plates. The conventional wisdom was that the 6FQ7 deleted the shield as unnecessary- and of course to save costs.

The D115 doesn't connect pin 9 to ground so there would not be as mush advantage there though the shield would still prevent the plates' electrons talking to each other- as much. Another advantage for the 6CG7 is that the 6CG7 is generally older production, I thought it wouldn't hurt to concentrate on those.

Of course I bought 10 times the amount I'd ever use- the panic of the tube no longer made:

6CG7 (4) TOTAL: 51

13- RCA 6CG7- “cleartop”- centre shield- US- NOS [5,8
5- RCA 6CG7- blk plate, D gtr, centre shd- NOS [8, 14
1- GE 6CG7- centre shield- NOS [5*
11- Omega by Hitachi- black plate- sq getter- cnt shd-NOS [3
2- Tung Sol- US- TNOS
7- Westinghouse 6CG7- blk pl, D gtr- NOS [1.5
8- Westinghouse 6CG7- blk pl, D gtr- Used? [1.5
4- RCA 6CG7- grey pl, halo gtr, cn shd- TNOS [6

But, at least in 2005, the 6CG7 was not expensive as you can see by the $ amont behind the [.

I was interested to buy the 11-"Omega" 6CG7's as they were the only Japanese tubes I ever saw that had black plates and square getters- plus they were NOS in the box for $3- couldn't lose. These turned out to be really well made tubes by Hitachi- though I can't find out their age- the boxes looked like late 60's styling as did the etched Hitachi logo. I was also pleased to find a pile of "Westinghouse" black plate, D- getter 6CG7's- and those were only $1.50. I also don't know who made those- they aren't RCA or GE, perhaps Sylvania?





PHOTO: The 15 very inexpensive Westinghouse 6CG7's

At the time I was buying the hot number 6CG7 was the RCA black plate, sidegetter "cleartop" and I invested heavily in those, buying 13 at $5 and $8. However, I only tried two kinds in the D115 and found the more conventional black plate, "chrometop" to have a greater clarity and transparency than the cleartop so I wish I'd bought more than the 5. And, the 6CG7 had a noticeably solid authority I didn't sense in the RCA cleartop 6FQ7's in the D115, confirming the 6CG7 advantages over 6FQ7.

These RCA 6CG7's of both kinds were such good tubes I began to be interested in their larger cousin 6SN7s.

Sometime, I'll get around to trying some more of these- especially the Hitachi's, but for now I'd say that either of the RCA' 6CG7's would be preferable to the 6FQ7.

Cheers,

Bambi B


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  • Favourite 6FQ7's - Bambi B 02/25/1021:52:43 02/25/10 (0)

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