Does swapping out old power tubes really improve your tone?

[ckyratm]

Hey guys.

So I recently put new power tubes in my RV50mk1 and I was curious as to whether the new tubes really would make the amp sound better or not. I did a little shootout experiment to find out. All the details are here:

http://ediblefoliage14.tumblr.com/post/ ... prove-tone" onclick="window.open(this.href);return false;

I'd love to hear what you guys think. Any comments, good or bad, are welcome. Check it out and thanks!

(Full disclosure, the new tubes were plugged in breifly before the test. Details are described here in the 6th post of this thread: http://ediblefoliage14.tumblr.com/post/ ... prove-tone" onclick="window.open(this.href);return false; )

[a.hun]

Did you rebias the amp for the new valves? No mention of it.


Andy.

[Jondog]

New tubes will improve old worn out tubes. Must be biased correctly.

[ckyratm]

I did not rebias the amp for this test. Partly because the ratings between each set of tubes was pretty close, and also because I wanted the only variable to be the age of the tubes.

That is a good point that I should have mentioned, thanks for pointing that out.

[Ronnie Robinson]

I think so if tubes are old/ knackered and well used. Tubes that have been in an Amp 4 years but have hardly had any use and only at low volume should still sound good. Tubes that have been in a year but gigged 3 - 4 times a week will get knackered a lot quicker.

Do u say how old the 'old' tubes were and what sort of use they have had?

[Jondog]

I did not rebias the amp for this test. Partly because the ratings between each set of tubes was pretty close, and also because I wanted the only variable to be the age of the tubes.

That is a good point that I should have mentioned, thanks for pointing that out.

But, by not biasing correctly, that would be a variable, one set being hotter than the other set, plus age.

[a.hun]

New tubes will improve old worn out tubes.

Yeah exactly. Old fairly worn valves will usually lose both top and bottom end punch and dynamics. But it doesn't depend on valve age, only on use. (Decades old unused ones will still perform as new because they effectively are new!) Which is why I find recommendations such as 'replace every year, eighteen months, two years, whatever' pretty much nonsense. Doesn't take account of how much and how hard the valves have been used. Also they often don't mention that preamp valves should last on average maybe 4-5 times as long as power valves.

Usually you'll find the people saying these things are people who'd like to sell you new valves...


Andy.

[ckyratm]

You guys are right about use over age, I probably should have worded those parts of my Tumblr post better.

In the case of my amp, the old tubes were used quite often during the roughly 3 years that they were in my amp. My band plays fairly regularly with 1-3 shows a month, regular band practices, all at full band volume. The tubes also went through recording a full album last year and a week tour this year.

Did you guys listen to the sound clips? What did you think about that part?

Usually you'll find the people saying these things are people who'd like to sell you new valves... [/quote]


Good point, that's one of the reasons I wanted to try this experiment.

[Ddjembe Mutombo]

Biasing wasn't important in this situation. If he is replacing old/used-up JJ 6V6 power tubes with new JJ 6V6 power tubes then the circuitry math suggests that no variance has taken place. I always have my amps biased when I change from stock tubes to my preferred tubes. However, I trust a quality tech more than the manufacturer.

This was a great test. A lot of tube swaps are placebo tests. Power tubes are notorious to cause this. I'd love to see someone do this with a very dark power tube vs a very bright power tube. We hear what we want to hear when we have no reference material. If we are told EHX is bright then we will believe it when we play them for the first time. However, when played against a Mullard, how much will we actually notice?

I am about to start recording guitars for an album. I am using a Rocker 30, JCM 800, AC15 that were last retubed in 2010. My original AD30 was retubed then too, but it was stolen in 2012 so I have a replacement AD30 that is rocking stock tubes. However, my Rocker and JCM haven't been played at a show since they were retubed. The AD30 has yet to be played at a show. The AC15 is the only one that has received a moderate amount of playing time. They all sound find just fine though, so I'm not worried.

PS. I set up everything, and I am using a SM81 with the most severe roll-off setting. Let me tell you that it is the best raw guitar tone I have heard. It is just a slight EQ and compression tweak away from being a pro guitar tone. Plenty of clarity along with tons of room for the bass. I really don't have to make room with the board's EQ. This is the first record I haven't used a 57 as the primary mic though.

[a.hun]

Biasing wasn't important in this situation. If he is replacing old/used-up JJ 6V6 power tubes with new JJ 6V6 power tubes then the circuitry math suggests that no variance has taken place.

Sorry but that is plain wrong. Not all JJ 6V6 valves will have identical current draw characteristics. (Far from it!!!) And that means some will be run much hotter than others at a given amp bias setting with substantial differences in tone.


Andy.

[ckyratm]

Biasing wasn't important in this situation. If he is replacing old/used-up JJ 6V6 power tubes with new JJ 6V6 power tubes then the circuitry math suggests that no variance has taken place.

Sorry but that is plain wrong. Not all JJ 6V6 valves will have identical current draw characteristics. (Far from it!!!) And that means some will be run much hotter than others at a given amp bias setting with substantial differences in tone.


Andy.

So if I'm understanding what you're saying correctly, had I biased my amp for this test, there probably would have been a bigger change in tone?

[jojo68]

Yes new tubes sound better and yes they must be biased.

[nlimbaugh]

I think it's hard for me to notice until my stuff breaks. I actually miss my old gt e34l's compared to the new JJmetallish tubes I can't remember what they are anymore. SO, my rig sounds good to me until it breaks or the preamp tubes get funny or noisy. I wish I had the cash to buy some NOS powertubes FWIW. I need to get the nerve to bias the thing. I have specific instructions I got from a tech. Oh yeah, my tubes in my rig are KT77's... amp sounds good, but the tubes seemed kind of mushy until I bought some killer preamp tubes. Sorry to get off topic.

[a.hun]

The difference in tone you get by replacing used valves with brand new but otherwise identical ones will depend on exactly how worn the old ones were. As Billy pointed out they will start degrading from day one in use but it is a gradual thing so unless they have had a lot of use the difference (even biased up properly) probably won't be dramatic.

One important factor is that some amp types deliberately run the power valves much hotter, usually the 30ish watt cathode biased 4xEL84 jobs like AC30s, AD30s etc etc or their 15W kid brothers and sisters. These give you much shorter (power) valve life spans, but that's okay, EL84s are pretty cheap to replace.

Other (usually fixed bias) amps run their valves at higher plate voltages but lower currents which is more efficient giving both more power and longer life. With the hotter running amps and modern valves you'll often get pretty noticeable sound degradation after just a very few hundred hours of use, sometimes even just a couple of hundred hours of hard use. In cooler biased amps they should last much longer, probably several times as long. And when you are talking about really high quality old production valves, well you can sometimes find original power valves in well used amps from the 70s still working well. My regularly used '74 Hiwatt had its first new ones just a few years back with it's previous owner. The life expectancy of high quality old valves is usually between 5 - 10 x that of any modern production valves. So properly biased in cooler running amps NOS valves can literally last for decades.

Some players I know tend to flog their power valves until they are basically dying to dead, and in that case replacing them with new ones gives a really nice surprise. Tone and dynamics are back, power is back, even though they'd never realised they were gone. But because many people these days tend to believe the 'replace them every 'X' months' advice they probably never get anywhere near that stage.

These people are all welcome to send me all their part used but still fully functional valves!


Andy.

[Randy Bass]

Biasing wasn't important in this situation. If he is replacing old/used-up JJ 6V6 power tubes with new JJ 6V6 power tubes then the circuitry math suggests that no variance has taken place.

Sorry but that is plain wrong. Not all JJ 6V6 valves will have identical current draw characteristics. (Far from it!!!) And that means some will be run much hotter than others at a given amp bias setting with substantial differences in tone.


Andy.

So if I'm understanding what you're saying correctly, had I biased my amp for this test, there probably would have been a bigger change in tone?

It's likely that there would have been less change in tone had you adjusted the bias for the new tubes since the variable of extreme cold or hot bias of the new set would have theoretically been eliminated, leaving only the variable of the tubes themselves relative to one another. This assumes that the different sets of tubes were noticeably different in terms of bias requirements, which is not known at this point.