Do you need matched output tubes? Is it worth the extra bucks? Are unmatched tubes just as good? There are at least three major things to match in output
Do you need matched output tubes? Is it worth the extra bucks? Are unmatched tubes just as good? There are at least three major things to match in output tubes that affect the sound of a pair of tubes in guitar amps. “Matched” may mean a number of things. And you may or may not want perfectly matched tubes.
Today’s tubes vary a lot. The vagaries of mechanical tolerances, materials chemistry and perfection of vacuum translate to variations in the DC bias point of the tubes, the AC signal gain of the tubes, and the distortion characteristics of the tubes.
Most of us are familiar with biasing to eliminate crossover distortion. We adjust the grid bias voltage so a little DC current flows with no signal. That current lets the two tubes hand off signal cleanly as the signal changes from positive to negative, and it is what you set when you DC-bias your amp. The tubes not only need to have a little current flowing with zero signal, but that current also needs to be the same for both tubes. That’s DC matching – selecting two tubes which happen to have the same current for the same bias voltage.
Some amplifiers have a bias adjuster for each tube that can effectively DC-match un-selected tubes. This is important enough that I put per-tube bias controls into the Workhorse amplifiers with LED indicators so you can DC-match your own tubes in the amp. If your amp doesn’t have separate per-tube biasing, you may need to pay the extra money for matched power tubes.
Each tube is also responsible for amplifying its own half of the signal smoothly. The AC gain (or “transconductance”) of the tube does this. If the AC gain of one tube doesn’t match the gain of the other tube, the result is distortion as well. Unfortunately, most tube testers can’t measure gain at full power, so gain matching on a simple tube tester may not reflect what you get in your amp. On the bright side, this is asymmetrical or evenorder distortion, and human ears perceive a little bit of this as a “sweetening,” not as distortion at all.
A high AC-gain tube on one side of a pair will hit overload more quickly than a lower gain partner will. A lower-emission tube may simply run out of electrons to pass, and may also overload earlier. Both of these may cause a lower clean power output from the amp.
Little quirks of the elements inside a tube can cause another form of distortion – little bends and twists of the signal within what is otherwise a linear part of its operation. This is the kind of difference that helps make an EL34 sound different from a 6L6. A lesser degree of this difference exists between any two tubes of the same type.
Distortion matching can be done, but this is a very muddy area. I’ve talked to some tube suppliers who claim to do this, and they have all been reluctant to discuss this area of matching. I’m guessing that most of the “distortion matching” is really a combination of DC and AC gain matching.
Some suppliers provide tubes matched by a grouping scheme, the idea being that if the tubes in your amp are from the “#5 group,” you can replace them with new pair from the same group without re-biasing. This is O.K.-ish, but since the tubes in a group like this have a range of values in them, don’t count on perfect matching from set to set. And bias is not directly tied to distortion, so I can’t see how the grouping system can do anything about overload or distortion.
Automated tube curve tracers exist that can run the tubes at full power, and record what the tube does at every point over its entire range. This kind of testing is great for hi-fi tubes, and is likely to be the future of tube matching and testing. Unfortunately, these are quite rare today.
Tubes also drift with heat and age. Tubes that were matched when you bought them can drift apart. You can see this graphically in the Workhorse amps by looking at the LED indicators after you have adjusted the bias current. The tubes will drift in and out of perfect bias slightly – which is actually O.K.
After all that, the answer to whether you need to buy matched tubes is a resounding “maybe…” You need equal DC bias currents per tube. If your amp is not one that lets each tube be adjusted independently, you need to buy matched tubes. Beyond that, your ears may or may not like the slightly sweetened sound of imperfectly AC gain matched tubes better.
As a musician, you need to check it with your best test equipment – your ears.
Kick off the holiday season by shopping for the guitar player in your life at Guitar Center! Now through December 24th 2022, save on exclusive instruments, accessories, apparel, and more with hundreds of items at their lowest prices of the year.
We’ve compiled this year’s best deals in the 2022 Holiday Gift Guide presented by Guitar Center.
Mystery Stocking is coming soon! Sign up for PG Perks below so you don't miss it.
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About Mystery Stocking
Each year, Premier Guitar likes to put out these mystery boxes as a part of bringing some fun to the holiday season. Remember, this is supposed to be a fun holiday treat! If the contents of this box will ruin your holiday, deplete the last of your bank account, or end your ability to see the good in humanity, it may not be for you.
- This year's Mystery Stocking will cost $44.95. ($39.95 + $5 Flat shipping)
- Each box will be guaranteed to contain $40 or more in value.
- US only. (Sorry World.)
- Make sure your shipping address is correct.
- Have your credit card ready to go before you refresh the page. Paypal is not available. Autofill may not fill in your information.
- There will be NO REFUNDS given.
- There has been a huge demand for these in the past. We really did sell out in less than 4 minutes last year. When they are gone, they are gone.
- One per household, one per person.
Q: What's in the Mystery Stocking?
A: It wouldn't be much of a surprise if we told you, now would it?
Q: Will I definitely get my money worth?
Q: Can I return it if I don't like it?
A: Nope. All sales final.
Q: What if I live outside the US?
A: Sorry, US only.
Q. How much is it?
A. $39.95 Plus $5 shipping
Q. When will it ship?
A. On or before December 10, 2022.
Q. What form of payment do you accept?
A. Credit cards only. Sorry, no Paypal for this.
Q. Can I ship to a different location than my billing address?
Q. I tried last year and didn't get one. Will I get one this year?
A. There is an overwhelming demand for Mystery Stocking. Be sure you have a fast internet connection and be ready when they go on sale. Last year we sold out in 3 min 33 seconds.
Q. I want to buy 5. How can I buy 5?
A. You can't. This year, we're limiting to one per household, so more people can get in on the fun!
Featuring the Adaptive Circuitry recently introduced on their Halcyon Green Overdrive, Origin Effects have brought us a pedal with a character all of its own and a new flavor of drive.
Origin Effects introduce the new M-EQ DRIVER mid booster & drive pedal. Based on a vintage Pultec studio EQ, this unique pedal offers a range of mid-focused tones, from a subtle mid boost to thick, resonant overdrive. Featuring the Adaptive Circuitry recently introduced on their Halcyon Green Overdrive, Origin Effects have brought us a pedal with a character all of its own and a new flavor of drive.
A choice of three mid-range frequencies ensures that you can boost just the right part of your guitar signal and, when pushed harder, can elicit a range of saturation from a classic “mid-hump” overdrive to fierce “cocked wah” distortion. Thanks to the Adaptive Circuitry, the high-end roll-off of the Cut control is reduced as the pedal cleans up. This allows for a smooth transition from warm overdrive to bright clean tones in response to playing dynamics or guitar volume knob changes.
Introducing... M-EQ DRIVER || Mid Booster & Drive
Built-in the UK to the highest standards, the M-EQ DRIVER continues the Origin Effects tradition of vintage, studio-inspired tones in modern guitar pedals. The Origin Effects M-EQ DRIVER is available now from Origin Effects dealers worldwide.
RRP: 259 GBP (Inc VAT) / 319 USD (Ex TAX)
For more information, please visit origineffects.com.
The new finish, according to Lava Music, is “inspired by the beauty of the golden hour,” a shining time just before sunset and after sunrise when photographers covet to capture stunning pictures.
With bright and warm golden hues, the new finish adds a brilliant metallic glow to the surface of Lava ME 3, complementing its AirSonic 2 carbon fiber unibody which features L3 Preamp with FreeBoost 2.0, delivers industry-leading sounds by breakthrough acoustic technologies, and houses a multi-touch display powered by Lava-developed HILAVA system.
Speaking of the HILAVA system, Lava Music also added four new effects: Nebula, Desert Rose, Cassette, and Edge of Breakup. As unique as their names sound, they are very much different from what we normally know about effects. Programmed into the HILAVA system, each of the four is powered by the company’s latest ArctanDrive algorithm and incorporates effects like Pitch Shift, Delay, and Reverb. And every one of those incorporated sub-effects comes with various parameters that players can adjust to design unique, overdriven sounds by just tapping on the multi-touch display. That said, those effects enable users to play with overdriven tone on an acoustic-electric guitar without even plugging in any external gear.
LAVA ME 3 | Now in Golden Hour | LAVA MUSIC
Lava Me 3 in Golden Hour is now available starting from $999 on LAVA MUSIC, Amazon, and local guitar dealerships near you.
For more information, please visit store.lavamusic.com.