Tube for an F1-X

[jazzyvee]

Now just finding the right tube. The one in there is called Ruby and is made in china and is 12AX7A no idea what that means.
I called a supplier here and this was recommended as a mild gain warm sounding tube. I know nothing about them so is this a good one?

http://www.hotroxuk.com/ecc803-12ax7-tungsol-gold-pin.html

[xlrogue6]

Just so you know, Jazzy, in the F1-X half of the 12AX7 is a unity gain buffer for the FX send, the other half is the first gain stage (drives the tone stack). The Ruby in your pics is several years old. The current Ruby 12AX7AC5 is well balanced harmonically with a nice bright top end. (Full disclosure: I'm in the midst of working with Tom at Magic Parts on a tube comparison project, initially we're working with the Ruby 12AX7AC5, Ruby 12AX7WBC, Electro Harmonix 12AX7, TungSol 12AX7 and the JJ 12AX7. Will post results when I've got them, hopefully in the next couple of weeks.)

[lbpesq]

Looking forward to your results, Kent.

Bill, tgo

[gtrguy]

I personally don't like Ruby tubes (or new Tung Sols, or Groove Tubes). I really like JJ's, old RCA, and other vintage USA, and vintage British, and vintage German tubes.
Sovtecs (did I spell it wrong?) are good well made tubes, but to me seem more 'grainey' and more suitable for modern hi gain guitar sounds.

[jazzyvee]

i have been reading this one Kent.
https://www.tubesandmore.com/tech-corner/12ax7-comparison-current-made-tubes?fbclid=IwAR3EwCEaHwxz9HE7sZkw-44JumiGTwpk3QTcQHxFBgH_4HPrSFUkaJebkQU

[xlrogue6]

Of course the problem with these tests (including mine) is that they're entirely subjective. You and I may hear completely different things from the same tube, and then there's variation in any given tube from production run to production run. Really, the best thing to do is to buy a couple or three (or more) different ones and see what sounds best to you. Since preamp tubes typically last for years, the good news is it'll be a while before you have to do it again.

[gtrguy]

I think of tubes as being like car tires. Some work well on dry pavement, some in the rain, some on the race track, some hold up a long time, etc, with all of them being a blend of traits. However, they all wear over time.

They all will eventually fail, and even that trait has various ways of happening. Some go out all at once, some (like the JJs I have owned) solder on forever, but their performance will get worse slowly over time. It's a good idea to find a brand you like and use it. It's also a good idea to keep a new one around to 'compare the tread' to the older ones you have, by swapping it in once in a great while. It's also a great idea to keep a spare handy. And beware, a lot of tubes, many with famous old time names, are not the same as the ones made years ago, but are instead now made in various places (like China) to other standards than the originals from back in the day were. Ask a good amp tech and they will tell you which ones they have seen fail most often. It is an eye opener.

[xlrogue6]

Most, if not all of the "old tube mfg. names on new tubes" are Russian, made in the same factory as EH and Sovtek for the same US distributor.

[sonicus]

A good friend  who was a specialist in the repair of tube amplifiers and who was involved with a publication called " Vacuum Tube Valley " explained to me of an observation that was made upon the examination of various power tubes such as 6L6 genre and 12AX7 / 7025 genre . He mentioned that in general that the Chinese tubes had a lower envelope vacuum that resulted in a lower threshold where the tube could be driven into harmonic distortion . The Russian tubes had a higher envelope vacuum and noted that they might interest me more so as a bassist seeking a cleaner lower distortion result at higher SPL levels ( SPL signal pressure level )     
 
He also mentioned that he actually also observed among various guitarists an appeal of tubes with a lower envelope vacuum who's preference is to be able to more easily enable tube distortion as was the case with the lower envelope vacuum Chinese tubes .

[gtrguy]

You can also pretty much swap in other 12ax7 type tubes (12at7, etc) with lower gain into 12ax7 slots, to get other tones and maybe less distortion (and less headroom). Many folks also don't know that a 12ax7 is really two tubes in one glass envelope.

I sometimes bypass the tone stacks on small amps, like vintage Fender Champs, by changing out the 2nd input jack for one that has a built in switch. Then when you plug a guitar into the 2nd jack you get at least a 1/3 jump in usable volume, because 1/2 of the preamp 12AX7 tube is used to push the signal through the tone controls. It is surprising how much power that takes up!

[jazzyvee]

Progress so far. Today I went and got a new tube for the F1-x and fitted it and the distortion is still exactly the same. I've been round and exercised all the jacks in my rig at least 100 times each, (highly tedious), nevertheless  It had t be done but still the pre-am is distorting at whatever level the gain is set at.
The overdrive light on my power amp does not light up at all whatever I use to drive the power amp, F1-x, SF-2 or direct from my bass.
When I plug my SF-2 in pre-amp mode on it's own instead of my F1-x there is no distortion however loud I can stand to it turn it up.
 also played my bass directly into the power amp and that is clean as a whistle. I have tried the individual F1-x outs one at a time , high and low pass and full range and still getting distortion. I have tried using a standard jack cable from my S2 bass and the sound still is distorted. Iv'e turned off the tweeter and still the same situation.
The individual volumes on the bass are about 2/3rds up and even with the master volume on a lowish setting the distortion is still there.
Any further thoughts.

[David Houck]

- Try running from the FX Send to the power amp.

- Try running from the direct out to the power amp (or to a mixing board).

- Try both inputs.

[gtrguy]

I can't remember if the F1-X has an output jack with a extra contact on it (inside the unit). If it does, cleaning the contacts may help. I use a small bit of very fine sandpaper pulled through the contacts a few times. I have had units distort like what you are describing, and that has been the problem. 

[jazzyvee]

I hope to get a chance tomorrow to try some of your tips. David I did try both inputs on the F1-x as i recall the second one has a has a pad on it to lower the input signal but that still made no difference. I never thought to try the send signal to see if that is also distorting. Let's hope i get to the bottom of this issue. Thanks again for your pointers I will report back on the situation. :-(

[edwin]

I can't remember if the F1-X has an output jack with a extra contact on it (inside the unit). If it does, cleaning the contacts may help. I use a small bit of very fine sandpaper pulled through the contacts a few times. I have had units distort like what you are describing, and that has been the problem. 

The FX loop return is usually the culprit here. Worth exercising that one.