Setup maintenance misadventures...

Just a post to calm down while changing the two valves of my Zoom G9.2tt guitar effects board. I bought these several months ago, but was afraid until now to proceed and on right account : no less than 34 screws and 3 connectors to remove. Some of the screws are horrible to reinstall especially the ones fixing together the valve base, the cover protecting it and the mainboard.

As I am writing this, I already changed and fixed one of the valve and its cover, but the second one refuses to go in its slot : something seems to block its insertion on the base and I’m afraid of twisting some of the 9 pins. :unamused:

Can’t believe that such a maintenance task is so complicated. I’m about to write a mail to Zoom with a “You made it on purpose, right ?” at the end of it.

So, an advice : if you have a G9.2tt and plan to change the valves for the first time, be sure to have very good reasons to do so !

Now back to work, hoping that this f*****g valve will kindly go into its base, finally…

Cheers and… any testimony of a similar experience is welcomed, just to assure me that I’m not the only one ! :laughing:

Why did you replace the tube?

Preamp tubes, especially when run in low voltage circuits like the one your describe, last a very, very long time. Decades. Or more.

Fixed, finally, with all the patience at my disposal. I changed the tubes because I read in several places that the bundled ones are crap, so, as tube replacement wasn’t too expensive, I thought that it was worth a try.

Now, after using the box for a while with the new ones, is there a difference ? Seems so, but as there is nothing more subjective than the sound you are hearing, I wouldn’t swear it and I certainly won’t put back the old ones to compare… So, a waste of time ? Maybe… :blush:

One thing is sure, I won’t change them again before a very long time.

Tubes in low-voltage circuits, like the ToneLab, are a gimmick. That’s not to say the ToneLab (and similar variants like the Zoom G9.2tt) don’t sound good; it’s just the tube isn’t operating as in a classic tube preamp circuit with tubes supplied with the voltages those tubes were designed to operate at. What you’re hearing is the solid state circuitry. The tube is passing signal but not contributing diddly-squat to the “tone”.

They quite often have a diddly-squat knob too :laughing:

Heh, heh, heh :laughing:

Those kind of boxes are great for folks that can’t track a roaring tube-amp in a decent room. But no silicon circuit is going to give the tone AND feel of a real tube guitar amp (with the possible exception of the Fractal Audio box … I’ve read good testimonials, but not had a chance to put it through its’ paces … yet).

Played with it again, this afternoon. Still not definitely sure that something is better. But again, ir just seems so, especially on some presets involving slight distorsion. I don’t really trust my ears, though : maximal placebo effect, I guess. Let’s say that if there is an improvement, it’s far from outstanding. It probably wasn’t worth the hassle : I learned something, at least. I changed the original tubes with '‘Made in China’ written on it for 2 Electro-Harmonix 12AY7 with… ‘Made in Russia’ as mention… :mrgreen:

@swamptone : If I understand you well, all the solid state amps sold with a tube only in the preamplification circuit are also gimmicks. The ‘real thing’ must be based on tube amplification with high voltages involved. Could you confirm ?

I knew when buying the Zoom that no board will ever compete with a full tube amplifier but, indeed it was both a matter of cash and place at my disposal. If you could confirm, it would give me the technical reason why tube amplifiers are so praised, even now.

Without getting overly technical, the typical 9-pin noval pre-amp tube can take 300 volts on the plates. It’s fairly common to see voltages of 200 to 300 in Fender and Marshall guitar amp circuits. The 12AY7 you used has a little less than half the gain factor of the more commonly used 12AX7 pre-amp tube.

Those tubes are made to be operated at far higher voltages than the ToneLab and similar circuits supply. I have read the voltages supplied to the tube heaters is insufficient to make them glow enough so users can see they’re working … and that Vox added an LED behind the tube to provide the illusion. In any case, the tube is in circuit but it’s not being worked nearly hard enough to impart beneficial tonal effect. It takes voltage, which requires heavy and expensive iron (power transformers) that drive up the price of “real” tube-based high voltage guitar preamps such as those made by Marshall, Mesa Boogie, etc.

None of this matters to many folks. They get a satisfactory result with minimal dollar outlay. It’s all a matter of what’s important to the end-user. I often use a Tech21 PSA -1 SansAmp for late night tracking without disturbing the household. It’s completely analog and solid state. It can be made to sound very good … but honestly … it doesn’t “feel” like a tube amp driven to saturation.

This why I choosed the 12AY7 : as the gain is less than the 12AX7, I thought that they would calm down a little the saturation effects that often sound quite harsh in the factory presets banks, which are often a start to shape something else. I’m not too much in the metal kind of sounds. And… no illusion LEDs here. :mrgreen:

Thanks for your precisions. :slight_smile:

Good guitar tone starts at the fingers :laughing:

How true! While I can get some decent sounds out of my guitars, I can’t get even close to what some of my friends are able to create with any guitar/amp combination.