• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Tube Rolling among the Great's 12AX7

The second Mullard 6C4 came in today and was a grey cv4058 box plate, the first Mullard 6C4 was a blackplate. Both sound great no problem there, what I ended up with was the Amperex 12AX7 long plate and the grey plate 6C4/cv4058 on one side and the Telefunken 12AX7 smooth plate and the 6C4 / EC90 black plate on the other side. I was not real impressed with the Mullard BH8 code 12AX7 longplate or with any of the Telefunken 12AX7 ribbed plate tubes. Not saying that they are bad tubes just that in these two amplifiers they don't sound that great. So my conclusion is that Mullard 6C4 are the way to go in black or grey plate and that the 12AX7 Amperex long plates and The 12AX7 Telefunken smooth long plate are my two favorite 12AX7 tubes both tubes sound very similar to each other. I still have to decide on what 12AX7s to use in stage 1 for the Mag and mic inputs . The Aux 1 and 2 bypass stage one tube and go directly into the second tube. I'm running a Sony CD deck into it and playing CDs. I plan on playing my Cassette deck through maybe a mic input to add some volume and the FM into Aux 2. Has the really old type mic connectors and I need to change them to RCA phono type.
 
Last edited:
Gary Mattis said:
Not exactly accurate information on the Amperex long plates at that website, My tube is a 8J but it also has a flat getter on top of the D getter from a 9 number tube.
Click to expand...

What did you find was not exactly accurate?

I'm not sure I follow, what's a 9 number tube?
 
Dswankey said:
What did you find was not exactly accurate?

I'm not sure I follow, what's a 9 number tube?
Click to expand...
Code 9 tubes is what I was trying to say, 1959 is a code 9 tube. They don't have my tube listed with the D Getter and the flat foil, has both and has the stapled plates , they show it but with welded plates and a 6 or 1956 code ? My tube is a code 8 or 1958 tube. Seems like their is some confusion about the long plate Amperex tubes because my tube is not identified properly for some reason ? . I was wondering why you have so many knobs on your bass guitar in the picture ?
 
Last edited:
Was wondering if I can use a 12 volt AC computer type fan on each amplifier to keep the output sockets and transformers cooler without picking up a bunch of noise ? I have a two wire 12 VAC feed right up front from the heaters for a dome light that I am not using. I know that the sockets are like a Fisher 400 and get hot and lose connection sometimes and that a fan really helps with that problem of 7868 tube sockets, mine has been pretty good but when I flipped the amplifiers over to work on the mic input plugs one tube had a bad connection after playing about a hour and good thing I was watching it when it happened. I put some RCA connectors on the two mic inputs on each amplifier. I'm not really using the mic inputs but I might want to use a mixer and mics some time so I went ahead and changed them.
 

Attachments

  • IMG_20190923_213649.jpg
    IMG_20190923_213649.jpg
    63.6 KB · Views: 9
Last edited:
Gary Mattis said:
Code 9 tubes is what I was trying to say, 1959 is a code 9 tube.

I was wondering why you have so many knobs on your bass guitar in the picture ?
Click to expand...

Ok, now I understand

As for the bass guitar in my avatar that is a custom made by Alembic bass for Phil Lesh of The Grateful Dead. It's known as the "Godfather" and or "Big Brown".

If interested here's a blurb about it. If you like deep rumbling bass then Phil's your man!

https://forum.phish.net/forum/show/1377253605
 
Gary Mattis said:
the D Getter and the flat foil, has both and has the stapled plates , they show it but with welded plates and a 6 or 1956 code? My tube is a code 8 or 1958 tube.
Click to expand...

The 6 or 8 would be correct as in 56, 58

IMG_20190917_174444.jpg

As I understand the codes goes like this either mC? ⊿8J or I6? ⊿8J

What does yours have above the

⊿ = factory code in this case Herleen, NL
8 = 1958
J = The month of October

Does yours look like this?

This is a mC6 ⊿8F


DSCN1217.JPG
 
I put the two Mullard 6C4 box plates in the PI and used a Telefunken long smooth plate as a substitute for another long plate Amperex and it worked out pretty good with those two tubes, I put a pair of KLH 10s on it too but I can't turn it up too much or It will blow the KLH speaker's, It is plenty loud enough for me and a pretty clear sound also . The sound is good enough that you don't need it crazy loud. I'm probably going to leave the Telefunken long smooth plate in because the long plate Amperex tubes are really expensive to buy. The short plate Amperex is not nearly as good as the long plate Amperex tubes. The long Telefunken smooth plates are better than a short plate Amperex. I'm not knocking short plate Amperex tubes at all as far as short plate tubes go those and Mullard are both pretty good but the better made long plates just seem to blow all the short plate tubes out of the water.
 
Last edited:
Yes
apachef1 said:
Amperex over the RCA 12AX7 Black plates?? Thats a first. Amperex is a nice sounding tube but a little congested in the highs with difficult classical chamber music. RCA are silky smooth topend with tight deep bass to rival all the Euro tubes.

On a side note - I see you mentioned Mullard 6C4 tubes? did you mean Mullard M8080 with the big box plates? Fantastic tube over the US 6C4
Click to expand...
But I have black box plates 6C4 now. I like RCA black plates but I don't think they compare to The Telefunken's and Mullards or Even Amperex Holland.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom