Will Vacuum Tubes Change Your Amp?

Many of us have spent a great deal of time & money swapping out vacuum tubes in our amps in a quest for "better tone." Let's apply the scientific method & see if it was actually worth it!

This test was made possible by using the incredible TWO NOTES Captor X: Click & affiliate link & help out the show!

0:00 intro
1:20 "special" tubes???
3:40 Human Perception
4:55 applying the Scientific Method
7:30 Joyo Zombie
10:14 5150
12:43 Power Tube test
13:56 For the Tone Elitists
16:58 Results
18:54 Conclusion

Many thanks to @jacksonwarddrummer @erikarko and John Souki for the incredible performances!

About Spectre Sound Studios:
I'm Glenn Fricker, engineer here at Spectre Sound Studios. I love making records, and after doing it for sixteen years, I want to pass on what I've learned. On my channel you can find tutorials on how to record guitar, bass, real drums and vocals. There's reviews and demos of tube amps, amp sims, drums, mics, preamps, outboard gear, Electric Guitar, Bass Guitar, and plugin effects.
We've covered Moon on the Water, played Bias FX, given you the absolute best in Stupid Musician Texts, ranted & raved about bass guitar, and this channel is where The Eagle has Landed.
Everything you've wanted to learn about recording Hard Rock & Heavy Metal can be found right here on this channel!

I also respond to your comments & questions: The best make it into the SMG Viewer's Comments series of videos. Loads of fun, lots of laughs.

Thanks for checking out my channel & please subscribe!

[achannel]

You'd think that people would be happy about not needing to buy rare, discontinued valves to get vintage tones.

[Anvilshock]

But there IS a noticeable difference! When I changed the tubes in my amp, the FEEL of my _wallet_ was so much lighter!

[johnmorrison]

But what type of paint was on the amp? That’s a huge difference in sound only the most experienced would notice.

[bghammock]

The mic movement changes were crazy eye opening.

[ChuckHaney]

The other thing that perpetuates the myth is this: First, tubes can and do go bad. If you've been playing your amp for months or years with bad preamp tubes you may not notice the amps less than stellar sound. You put in new tubes, maybe they aren't the same brand you had before, you turn on the amp with tubes that are actually working correctly and suddenly it sounds good and you figure it must be the new brand you've used. Wow! "Those Jim-Bob tubes are GREAT!!!" Maybe, but really it's just that your shit tubes sounded bad.

[crottedepingouin]

i've always seen the tube change as a way to cutomize your amp, a way to fix the little things you want to improve about your amp. today, glenn made me question everything, i was already ready to come up with criticism but this video answers all questions and doubts about the matter. this is the best spectre sound video so far (and i've been subscribed for a while). great job glenn, and thank you. changing people's mind on the internet is not an easy thing!

[Fiddling_while_Rome_burns]

This test is complete bunk, everyone knows changing tubes doesn't work with a red guitar.

[alexholmes]

Thank you for such a thorough and precise test, we need more of this in music. Especially loved the "warm doesn't mean anything" part.

[jimmoss]

The bias is setup in the local feedback resistors, called self biasing, in small signal tubes like the one we are talking about. The frequency response is also a function of the tube resistors and caps. None of this will change if the circuit was properly designed. The idea in good design is to make the resistor bias and frequency performance dependent on the the local circuit itself and therefore be immune to variations in tube construction. The OPEN LOOP circuit which has none of these protections. Those will depend on the tube for the circuit's performance. (That is what a college education in electronic engineering will get you. I am an EE, Musician, Studio Owner, Equipment Designer.) So how swamped (technical term) the circuit is will determine the performance as outlined above. Changing a 12AX7 with another 12AX7 of another brand, in a properly designed circuit, will make no difference at all. The proper designed circuit depends very little on the actual tube other than for gain. You might be thinking of POWER output tubes with their ability to have a pot for the bias setting.

There are a family of 9 pin tubes in the 12 - - 7 tubes. These are optimized for either Voltage Grain or Power Drive capability. The 12AX7 is one of the worst in the family. These were made for cheap 5 tube AM radios. These can cut back on the number of tubes that are needed in the AM radio. This is called Economics. The 12AX7 driving a high Z load will still have a lot of distortion, but lots of gain. If you replace that 12AX7 with a lower gain tube with a lot of drive capability like the 12AU7 then since this tube can drive more power into it's load without distortion, but with less gain, this will make the quality will go up and the loudness go down. Loudness and Tone is all about the circuit around the tube. This can be tested with an Analog Signal Analyzer. So the range of tube designs were meant to address these different requirements.

You might want to examine the Decoupling circuits of each amp section. I updated mixing consoles by adding bigger Decoupling Caps. I checked the console with a Kick Drum Sample. This was causing the input of one channel to drive all the channels into saturation. These were cheap performance mixers.

[bmcash]

Finally, someone who actually did a proper scientific study on tubes; only variable was the tubes and everything remained constant. Bravo, sir.

[edcook]

Bottom line, Glenn might take heat for this test, but he is just trying to save us some money. Thumbs up.

[Hellseeker]

Glenn's like Santa with this one, saving everyone money for Holiday's. Make sure to re-bias, double check that shiz.

[tonyhook]

Thanks, Glenn. All these years I couldn’t hear what everyone was going on about. I thought it was me. Turns out I was right, nothing much was happening. Great content, as ever.

[transistorradiorecords]

I think the JJ sounded special, kind of magical unicorn dust sound. Warmer yet blissful. Of course I have special Tube speakers.

[deadsky]

This is THE most thorough application of the scientific method outside of a formal scientific or academic setting. I'm sending this to my brother who's an educator. This needs to be shown to kids in middle school!

[hde]

I can already tell you there's gonna be more "wah wah wah!" about this video than a Metallica solo. 🤣 Great video Glenn.

[vaibhavahujate]

Yesss. I've been waiting for this video since the Klark Technik Review. It amazes how people (even smart ones) want to validate their purchases without considerable evidance.
I hope you'll release the tracks to those so I can show this at school to all my classmates and teachers as well who might say something about YouTube not being enough due to its compression algorithm.

[sumyupee]

The biggest shock to me was how close the el34s were to 6l6s. That's nuts. It's nice to know how little the power tubes actually matter in regards to tone. Thanks for the scientific approach.

[Jake]

An incredible eye-opener. As of now, on this day, i solemnly swear to never smell another cork again. Thanks for showing me the light. Furthermore, the mic placement example really deserved it's own mini video demonstration because it's a very valuable piece of recording knowledge that has a much more dramatic effect than id ever thought. This is a great video. Just Excellent. Loved the null comparisons as well. That told me everything.

[LuisVascMusic]

I was expecting these results but it still amazed me how there's basically NO FRIKING DIFFERENCE. At least not a very noticeable one, specially in a mix. If you want to be picky go ahead and use different tubes but in reality no one in a audience will notice.