Tube question: short plate Vs Long Plate 12 Ax7's

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stratkiwi
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Tube question: short plate Vs Long Plate 12 Ax7's

Post by stratkiwi »

I bought my first tube amp head which is the Laney Cub 15w head, it came with the ruby branded tubes from china. I have been thinking about the idea of changing the preamp tubes and output tubes to JJ tubes. What would installing long plate tubes in the pre-amp achieve?. Also are the ruby branded tubes any good ? or should I change out to the JJ tubes?.

I am very new to tube amps as I have always persevered with solid state amps

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by Marshmallow »

Frey wrote:I like long plate 12ax7s, especially in the first position. The one JJ makes is pretty good. I'd definitely recommend changing to JJs. Even if they aren't that much of an improvement you can always keep the rubys as spares.
how does it differ from chinese tone wise?

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by Molly »

I've just posted an article in this thread that might be of interest:

http://nzguitars.com/forum/viewtopic.ph ... 7&start=15

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by sizzlingbadger »

The Ruby branded Chinese valves are excellent, leave them in there until they fail. Long plate valves tend to suffer from microphonics in combos due to there construction. JJ's are very rugged partly due to their very short plate design.

I wouldn't differentiate the tonal characteristics of valves by the length of the plate. The TungSol 12AX7 is a great sounding tube in V1 and isn't a long plate. The Sovtek 12AX7LPS is great in PI positions but is a bit flat in V1 in my experience and thats a long plate.
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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by stratkiwi »

Molly wrote:I've just posted an article in this thread that might be of interest:

http://nzguitars.com/forum/viewtopic.ph ... 7&start=15
I just read that and was quite interesting

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by stratkiwi »

sizzlingbadger wrote:The Ruby branded Chinese valves are excellent, leave them in there until they fail. Long plate valves tend to suffer from microphonics in combos due to there construction. JJ's are very rugged partly due to their very short plate design.

I wouldn't differentiate the tonal characteristics of valves by the length of the plate. The TungSol 12AX7 is a great sounding valve in V1 and isn't a long plate. The Sovtek 12AX7LPS is great in PI positions but is a bit flat in V1 in my experience and thats a long plate.

When you talk about positions like V1 I am not quite understanding what you are saying there, when I look at the back of the amp head I can see the 3 12AX7 tubes and right beside them is the EL84 tubes so would v1 be the first of the 12ax7's that I see?. Apologies for the newbie question as I said in my OP that I am new to tube amps and I will take yiour advice and leave the ruby tubes in there till they fail.

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by sizzlingbadger »

V1 is the first valve in the circuit, 90% of the time its the one closest to the input jack. Looking at Laney Cub photos though it would appear yours could be one of the exceptions. Here I have labeled them for you.
R15.jpg
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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by Reg18 »

I tried a JJ long plate in V1 on my Vox and preferred a short plate in that position but can't remember exactly why, I liked the long plate better in V2 though. As stated above they are more prone to microphonics because of the design so for the small difference you might hear it's probably best to play it safe and go with short plates. I've recently done some swapping of tubes to see what I like including pulling out some Ruby valves(both pre and power amp valves) I put in some JJs,Tung Sol,some NOS and some Chinese tubes, and the differences were minor and not necessarily better or worse....just different (although I ended up putting a ANOS Phillips 12at7 in V1 which lowered the gain and sounded better to my ears) I assumed the Ruby's would be noticeably worse but they seemed just fine actually. It can't hurt to throw some new ones in though and just keep the others as backups like Frey said.

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Re: valve question: short plate Vs Long Plate 12 Ax7's

Post by stratkiwi »

sizzlingbadger wrote:V1 is the first valve in the circuit, 90% of the time its the one closest to the input jack. Looking at Laney Cub photos though it would appear yours could be one of the exceptions. Here I have labeled them for you.
R15.jpg
Thanks for that, made things a lot more understandable and I appreciate that, the tubes in the laney cub head are set out exactly the same.

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