Tube Replacement

[180gRoc]

What are the options, pros and cons, or other relevant considerations when considering a tube change for a desktop Tonelab?

How often should the tube be changed under normal use?

Thanks in advance!

[180gRoc]

I found this thread on the topic, and will monitor it, as it seems to have a head of steam going. Still curious how often to change under regular use though.

http://www.valvetronix.net/forum/is-tube-changing-in-tonelab-valvetronix-worth-the-hassle-vt800.html

[Nik]

A preamp valve run at low voltage - as in the Tonelab - does not wear appreciabley. Useful life could be as much as 10 years.

[180gRoc]

Thanks Nik... I suspected as much as far as voltage goes. I may have to pick up a couple options to try some different tubes (er... valves) myself. Luckily there's a Mesa Boogie dealer down on the corner!

[Nik]

Invest in a Groove Tubes GT12AX7M. It's their remanufacture of the old and revered Mullard design. It's not cheap, but it's a really worthwhile upgrade to the Tonelab in my experiance.

[Blueswaite]

I put a GC ECC83 in mine and like it alot.

[180gRoc]

Well... My GT12ax7M has been back ordered for three weeks, so last night I went and got what they had, a stock Mesa Boogie 12ax7.

I set up a test by selecting six models. Three clean and three overdriven. I saved a preset with no effects for each (assuming I would knock some knobs around when I changed the valve) and recorded a simple progression straight into my firewire interface.

I set the tonelab up on an insert and bounced six files to disk on the stock tube, each with a different model. The six models were:

UK 80's w/ UKT75
UK Modern w/ UKT75
Recto w/USv30
2X12 Black
4X10 Tweed
Boutique Clean w/UKH30

I then pulled the tube and replaced with the Boogie and repeated the process. I arranged the finished clips to play comparatively one after another. I had intended to post them, but will save the trouble because there was almost no discernable difference.

The stock tube (a Russian EH, not Chinese) was maybe very very slightly louder. I'm afraid I may have compared apples to apples with the Mesa Boogie. I am curious when the GT Mullard comes in if it may be different. I will re-test at that point. So far the stock tube wins.

Anyone have any suggestions what other tubes I might try beyond the Mullard copy?

On a sidenote, I was suprised to see the little LED under the tube. I suppose I shouldn't have been, as the tube (or what I thought was the tube) lights up brightly with no warm up time. Silly marketing fluff? A waste of voltage in my opinion.

[Nik]

On a sidenote, I was suprised to see the little LED under the tube. I suppose I shouldn't have been, as the tube (or what I thought was the tube) lights up brightly with no warm up time. Silly marketing fluff? A waste of voltage in my opinion.

People expect valves to glow. Generally, preamp valves hardly show any glow at all, because the glowing heater coil is buried in a network of grids and plates. The heater coil in the tube in the Tonelab gets 6 volts instead of the standard 6.3 volts - a small difference, but it might reduce the glow a little.

Anyway, many or maybe most companies that put visable preamp valves in products put a LED behind them to give a nice, bright orange glow that people expect. I'm tempted to change mine for a blue one.

[180gRoc]

I'm tempted to change mine for a blue one.

Now that would be cool... I could see doing that.

As far as the valves go, I'm not up to speed on the different lineages and similarities of preamp valves. I can say that the MB I put in looks exactly like the EH I took out. Looks like they were made to the same specs, maybe even at the same place. I didn't suprise me when I heard no tonal difference.

So... what's compatible but different?

[bitzerguy]

I replaced the original EH with a JJ ECC083s tube in mine. I use the JJs in my AD120VTH as well. But I did not do a detailed recorded comparison. I'll try to do one this weekend. I still have the original EH tube.

...Dean