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Preamp Tubes

joelb79

joelb79

Mar 22, 2006
4,558
315
Lansing, Michigan
#1
I own a hartke 7000 head, and it comes with a 12ax7 tube which i recently replaced with a groove tubes 12ax7 in search of something a little warmer than a sovtek.

But i was wondering if there were other tubes i could replace that with, such as a 12at7. Im looking for something a little warmer that verges on overdriving when turned way up. any suggestions?
 
#2
The 12AT7 will just have lower gain than the 12AX7. There shouldn't be a difference in tone. The real difference is between brands, most of which will sound better than Sovtek for bass.My favorite is the JJ ECC83.

Try subbing a few different 12AX7 brands in your amp and listening to the difference...somewhat subtle but noticeable.
 
#4
Differences in mu (gain) are not the only considerations with 12AX7s, 12AT7s, or 5*** whatever tube types. I hear about people swapping tube types all the time without any consideration that several part values inside the amp should be changed as well to match.
 
#5
I just snagged a Chinese 'gray plate' 12ax7 from Lord Valve. It was $25 which seems like a lot for a 12ax7 but... It is a great sounding tube. Yesterday I did a bunch of AB'ing. Currently I have the gray plate on 1 side and a JJ on the other. The JJ has less gain by about 1 setting (vol at 4 vs 3 for the gray plate). Has a very clean, hifi character. The gray plate seems to have more bass and more low mids in it. It isn't muffled but it is definately 'warmer'. I'm not into the distortion thing so I didn't push the pre into clipping. Really a nice sounding tube. When I talked to Ned, I mentioned that I was interested in re-tubing pre (I was ordering a set for my Fender Guitar amp) and he dove on this Chinese tube as his fav for bass. I think I agree.
 
#8
Let's see...

In an SWR SM-400, I compared the JJ to EH, Sovtek, and GE. Fuller, clearer, smoother.

In a Bassman 50 silverface, compared against the old stock Fender branded tubes. Less noise, fuller, less distortion.

Oddly, in a Bassman 100, I liked the GE better than the JJ, but I think the JJ might have been not as good as usual.

Peavey Max preamp, EH and JJ sounded similar.

And a few years ago, Eden WT-300, didn't seem to matter what tube went in...all sounded the same :)
 
#10
tornadobass said:
Let's see...

In an SWR SM-400, I compared the JJ to EH, Sovtek, and GE. Fuller, clearer, smoother.

In a Bassman 50 silverface, compared against the old stock Fender branded tubes. Less noise, fuller, less distortion.

Oddly, in a Bassman 100, I liked the GE better than the JJ, but I think the JJ might have been not as good as usual.

Peavey Max preamp, EH and JJ sounded similar.

And a few years ago, Eden WT-300, didn't seem to matter what tube went in...all sounded the same :)
Click to expand...

That is fairly consistent with what I found. I did compare against Tung Sol, Mullard and NOS JAN Phillips. TIn a bass pre, for my needs the JJ case the better sounding tube. The grey plate tube is quite different and is much thicker / warmer sounding. At about double the cost, it ought me.

I have a very simple 1 tube mic pre (Bellari/Rolls MP105). I think I'm going to do some exerimenting there and take some variables out of the loop.

I'm, not used to dramatic changes while tube swapping being 1. common 2. good. I have heard dramtaic and bad... THis is something new.
 
#11
4Mal said:
I just snagged a Chinese 'gray plate' 12ax7 from Lord Valve. It was $25 which seems like a lot for a 12ax7 but... It is a great sounding tube. Yesterday I did a bunch of AB'ing. Currently I have the gray plate on 1 side and a JJ on the other. The JJ has less gain by about 1 setting (vol at 4 vs 3 for the gray plate). Has a very clean, hifi character. The gray plate seems to have more bass and more low mids in it. It isn't muffled but it is definately 'warmer'. I'm not into the distortion thing so I didn't push the pre into clipping. Really a nice sounding tube. When I talked to Ned, I mentioned that I was interested in re-tubing pre (I was ordering a set for my Fender Guitar amp) and he dove on this Chinese tube as his fav for bass. I think I agree.
Click to expand...

That is so cool. I did the same thing a little while ago. My tube in the Metro was getting old and I called up the guys at Eden and they said put that very same gray plate Chinese tube in. It is amazing what that did for my sound. Bold, is the word that comes to mind.
 
#12
tornadobass said:
And a few years ago, Eden WT-300, didn't seem to matter what tube went in...all sounded the same :)
Click to expand...

I'd heard that the Eden amps don't actually use the tube for the gain stage (they're used for impedance matching, or possibly for the Marketing Stage ;) .. so your experience fits. Maybe someone who's inspected their topology can comment on this.

In a week or so I'm going to try a pair of Jan/Ge 5751s in my demeter. No idea how this will sound. I'd heard a couple of recommendations for the same brand 12ax7, but the only ones i found cost a fortune. these were reasonable.

Of current production tubes, the best I've used so far are the Sovtek 12ax7 LPS. Much nicer than the chinese tubes i've tried, and much nicer than the WA series Sovteks. Greater warmth, more bass, AND more clarity. Nice trick to pull off.

In my stereo the best sounding tubes I've tried are new old stock RCAs. I've tried several different vintages and types. happily, the ones that I've liked best are not the oldest ones or the types shrouded in the most mystique. I may pick up some RCAs for the demeter at some point. I'll report how they sound if i do.
 

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