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Songbirds Magnatone Vibrato

Magnatone Vibrato: How It Works

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In the 1960s there were plenty of amplifier manufacturers that were clamoring to compete with giants like Leo Fender. Of course, competition breeds creativity, and many companies struggled to find their niche. Silvertone, for example, secured their place as the “budget-friendly” Fender competitor and monopolized the mail-order catalog. Ampeg cornered the bass amplifier market. Vox and Marshall voiced their circuits in a distinctly different way that produced the “British sound.”

Enter, Magnatone. Known for their clean, but not as sparkly as Fender, tones and their stiffer, less-responsive overdrive, there wasn’t a wide-open field for their company to shine. Sure, the Magnatone sound is different and excellent in its own way, but it wasn’t spectacular enough to dethrone the Fender royalty. Except for one special thing; one secret and proprietary effect that would cement Magnatone in the halls of amplifier history: true vibrato.

*Magnatone ended its run in the mid 1970s, but there has been a modern revival. If you are enamored with the sound, you can purchase a brand new reissue of one of the classic circuits. Or, you can always try your luck at finding a vintage one that’s hoping for resurrection. Most fans now lovingly refer to them as “Maggies”.

 

Vibrato versus Tremolo:

Let’s clear up a confusing detail right away: the difference between tremolo and vibrato. Many vintage and modern amps include onboard effects like reverb. The most common and ancient effect is tremolo. This is a post-amplification effect that modulates, or changes, the instrument signal by rapidly changing the volume. Commonly, you can alter the intensity of the tremolo, or its depth, as well as the speed at which the volume change happens. This allows the player to layer on a slow, rhythmic pulse all the way to a fast, trembling warble. Remember: tremolo is a manipulation of output volume.

Vibrato is a change in pitch. Say, for example, someone sings the musical note “C”. Vibrato happens naturally in healthy singing, and if you were to look at a recording of that singer, you’d see an audio wave that subtly fluctuates around the note “C” by going slightly sharp, then flat, then sharp, then flat, etc. Vibrato sounds organic and is commonly heard in the human voice, orchestral strings like the violin, and even guitars and fretted instruments on longer notes.

In the 1960s world of amplifiers, it was pretty simple to create tremolo, a fluctuation in volume, but extremely difficult to create vibrato, a fluctuation in pitch.

The difference between tremolo and vibrato is easily confused, but it’s further convoluted by the fact that Fender called their effect “vibrato” on many of their amps (and still do!) when in reality, the effect that they were producing and manipulating is tremolo, a fluctuation in volume, not pitch.

 

Hold Up:

You may be wondering if the difference between tremolo and vibrato is noticeable, or if it even matters. Yes, it is noticeable, and yes, it matters! The two effects are closely related, but they do have distinctly different sounds. Check out this video from one of my favorite technicians of all time, Uncle Doug. Around the 18:30 mark, you can hear a side-by-side comparison of tremolo and vibrato… plus, he’s using a vintage Magnatone amp!

As you’ve probably surmised, Magnatone figured out a way to create real vibrato in their amplifiers. They coined their effect “true vibrato”, and kept the circuit a secret. That didn’t work for long, though, as amp technicians were able to get their hands on the Magnatone true vibrato, trace the circuit, and see how it works under the hood. Speaking of…

 

How Magnatone Vibrato Works:

Traditional tube tremolo (like the kind found in Fender amps) is pretty straightforward: take a tube that can function as an oscillator, then have it throttle the audio signal before it gets to the output section of the amp. It can also be done by oscillating the signal at the phase inverter, which is technical nerd jargon for “you can have the audio signal cancel itself in rhythm to create the effect”.

Magnatone true vibrato uses a rare and super special component called a varistor. A varistor is a type of semiconductor that is kind of like a common resistor. Instead of being one permanent value, however, the varistor can change its electrical resistance based on how much voltage is applied to it. They are most commonly found in surge protection, so think of it this way: if current is flowing normally through a circuit, the varistor will have very little resistance. If a voltage spike happens and the circuit starts to overload, the varistor will “see” this irregularity and will quickly increase its resistance until the spike has been resolved. This helps protect the rest of the components.

Now, this isn’t helpful for audio. Magnatone realized that a partner circuit had to be employed to make the varistors shine. This is an LFO, which stands for a “Low Frequency Oscillator”.

LFOs are incredibly common with audio. Most modulation guitar pedals, synthesizers, and keyboards use them. They simply generate an audio wave that is too low for human hearing. Then, this wave can be controlled like a common amp tremolo circuit by manipulating the intensity and the rate. Most importantly, other audio signals, effects, or controls can be attached to the LFO and “ride” it to create interesting and novel sounds.

 

So, in combination, the magic and mystery of Magnatone true vibrato is this:

Instrument audio signal enters an amplification tube. At the same time, an LFO signal is being injected into the same tube. This LFO is strong enough to rhythmically vary the voltage at the tube, meaning that the output signal of the tube also varies accordingly. The tube has a separate varistor attached to both the positive and negative outputs, so the out-of-phase audio signal (which has been juiced with the below-human-hearing varying signal) gets squeezed and “corrected” by each varistor. When the two out-of-phase signals are combined at another amplification tube, the summed sound is the smooth, musical vibrato that we love. If you’d like to see an explanation using a schematic, check out this video at the 34:05 mark.

 

The Maggie, the Myth, the Legend:

Much to the despair of amp technicians back in the day, Magnatone was one huge step ahead: they kept the values, construction, and technical details of the varistor close to their chest. The actual component doesn’t have any markings on it, and attempts to recreate it have been futile. That is, until the Maggie revival in the 2010s. The current company that produces these amps spent a ton of time, research, and development in reproducing the varistors, and while their construction is still a secret, it’s refreshing to know that the knowledge of how to make them hasn’t been lost to time.

 

Is It Worth It?

To me, a vintage nerd, technician, and enthusiast, yes. Yes, the Magnatone true vibrato is a completely unique sound unlike any other, especially in comparison to traditional tremolo. It’s a subtle, musical, and organic sound that sits with the music. Tremolo interrupts the music more – it sounds choppier and more abrasive once you’ve tasted the sweetness of vibrato.

That being said, the Magnatone sound is a sum of its parts. An all-tube ensemble, vintage (often sub-par quality speakers), and the ability to jumper channels on the amp give the vibrato a charming grittiness, warmth, and mojo.

If you’re looking for just the sound of the vibrato and don’t need the full amplifier, there are some great modern pedals that try to faithfully emulate the Magnatone vibrato sound. Check out the Equilibrium by Alexander Pedals, Magnavibe by Bigfoot FX, SurfyVibe, and Killer V by Crazy Tube Circuits.

 

Wrapping Up the Vibes:

Thanks for learning about this unique and magical circuit from the 1960s! Keep in mind that not all Magnatone amps have the true vibrato circuit under the hood, but models that do can still be found in the wild. Keep an eye open for vintage ones at places like the Orlando Guitar Expo, and there’s always Reverb. Stay tuned for more interesting and nerdy offerings, and contact us if you have any questions!

Songbirds Magnatone Vibrato
Songbirds Tubes vs. Solid State

Tubes versus Solid-State

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There’s a lot of information (and confusion) out there regarding the constant debate over tube amplifiers versus solid-state amplifiers. Everyone has their own preference, but in general, most professional players agree that tube amplifiers are superior. Let’s look at why that is the case and compare how both tube and solid-state amps are constructed and function.

 

Note: With a few exceptions (looking at you, gorgeous Roland JC-120), I am firmly planted in the Tubes-Are-Better camp. I’ll be as unbiased as possible in discussing the pros and cons of each, though.

 

Overdrive Tone:

The real conflict between tubes and solid-state swirls around the way that each product produces distortion and overdrive. When an audio signal enters the amp, it gets amplified by either tubes or transistors. Transistors are smaller, more cost-effective devices that have a cut-off point. When the incoming signal gets loud enough to reach that threshold, the transistor clips the signal, or cuts off the tops and bottoms of the audio waveform. This gets further amplified by other transistors and eventually results in a distorted sound at the output.

Tubes don’t have a cut-off point in the sense that they clip the audio signal more gently, as if in a curve. This results in a more organic, smoother sounding distortion that most people find more desirable. There’s also the addition of even-order harmonics with tube amplification, which means that faint distorted frequencies ring out at higher octaves of the fundamental note. These harmonics aren’t produced with transistorized circuits, and their inclusion rounds out and enriches the overall audio signal.

The lack of hard cut-off point with tubes results in the touch sensitivity that many players enjoy. You’ll often see this referred to as “edge of breakup”, meaning that, under the right conditions, the instrument can be played without distortion when the strings are picked lightly, and with distortion when they are strummed with more force. This trick is more difficult to achieve with transistors. What’s more, tube overdrive and distortion creates a natural audio compression that helps the audio signal sound richer, warmer, and fatter, especially at high volumes.

Speaking of high volumes, tube amps need to be relatively hot to work properly and sound their best. Most tubes sound anemic and hollow at low volume, where transistor circuits do just fine at a whisper. A lot of players don’t have the luxury of knocking the walls down with added volume.

 

Durability:

Tube amps are much more fragile than solid-state. Tubes are made of glass and hold an internal vacuum. Even though they are protected by the amp’s cabinet, a wrong bump or smash can break a tube. Tube amps also run on significantly higher internal voltage than solid-state, and although the components are rated to handle the current, it’s still a lot of energy running around and causing stress. Solid-state amps can usually be thrown off a moving truck and still function (please don’t try this at home!), but problems at the component level are more difficult to diagnose when they arise.

 

Repair:

Unfortunately, most solid-state amplifiers are built to be disposable. It’s much more challenging to fix a broken solid-state amp, and hourly repair costs can quickly balloon when the required fix is complicated. When solid-state amps fail, it usually is a matter of weighing the cost of repair versus putting that money towards a new amp or better model. The transistors that amplify the signal in solid-state amps require more connected components to function correctly, and the circuit boards are always more populated and intricate. In digital circuits, proprietary chips may be involved that can only be replaced from the manufacturing company, not repaired.

On the other hand, tube circuits involve larger and fewer components. The tubes do all of the heavy lifting, so in a super simplified sense, the other components are just carrying current and making the necessary connections to help the tubes do their job. Most tube amps are designed with future repair or modification in mind. In short, it seems like most solid-state manufacturers don’t want you to repair the product, while most tube manufacturers know that you will eventually.

 

Realness:

Tube amplification was invented before solid-state, so the natural progression of technology is that solid-state will forever try to capture, emulate, and improve on the sound of tubes. Has it happened yet? Many players including myself would argue no, not at all. Solid-state sounds close to the real deal, especially with digital modelers, but that extra five percent of je ne sais quoi is what has yet to be accurately captured. The combination of even-order harmonics from an amp’s tubes, plus the volume saturation, plus the physical act of moving air in the room from the speaker is, as of now, the missing piece from solid-state products.

 

Cost:

There’s no bones about it: tube amps are far more expensive than solid-state. This is because the tubes themselves are costly on a parts-level, plus tube amps require expensive output transformers whereas solid-state usually relies on transistors to do the job in the output section. Tube amps that have onboard effects like tremolo, true vibrato, and reverb usually have extra transformers, chokes, and tubes for those sections as well. What’s more, tube amps that are intended to last decades are often hand-wired or constructed with point-to-point wiring, meaning that all internal components are easily accessible and visible in case a repair is needed. Building an amp in this fashion requires literal hands-on work, so labor costs are higher.

 

Mojo:

Guitars and cars are always compared, so a tube amp is like a classic American muscle car and a solid-state is like a brand-new vehicle that just came off the line. You may find enjoyment in both, or you may prefer one over the other. At the end of the day, your amp should be like your guitar – it should make you want to play more! I find that tube amps have extra mojo and “coolness” that gets me excited to pick up my instrument and play some tunes. Your goal is always to find that piece of gear that makes you want to do the same.

 

I hope that this helped shed some light on both sides of the eternal tube versus solid-state debate! Let us know if you have any questions, and if you’re interested in your own custom tube amplifier, check out our custom amps page!

Understanding Fender Amps

Fender Amps: A Comprehensive Guide

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Fender, the beloved guitar, amp, and effects company, has been producing excellent amps since 1946. Over the years, the products have evolved and changed so much that it’s difficult to keep them all straight, let alone understand which sound may be right for you and your music. I’ve broken the following information up into eras – most vintage enthusiasts use the same categories to discuss the amps. Modern models that are being sold today are mentioned at the end.

It’s important to note that the vintage amp market is ludicrously expensive, and will likely only continue to appreciate. As with classic cars, the number of available units will never increase, and as time marches on, more and more amps will be lost, only further pushing up the price of surviving models. I do not personally own any vintage Fender amps, but I have had the pleasure of playing several so far. I have scratch-built and repaired most of these models, though. The nice thing about Fender is that most amps are still derived from their original ancestors, so you can get the sound of a vintage piece at a fraction of the cost by buying a newer reissue. Likewise, you (or someone you know, like Justin at Songbirds) can build a new amp to the exact specifications of the vintage ones, allowing you to experience the exact sound and feel of the original circuit.

*Note: If you come across a vintage Fender amp and are in the United States, it’s advised to operate it with a variac set at 117 volts AC. If you aren’t experienced with amp repair, vintage gear, or electronics, it’s recommended to send it to a repair tech or someone with experience before even powering it on. You could get hurt or shocked – for example, vintage tweed amps were made with a sheet of asbestos covering the chassis… oh, the past!

Now, without further preamble, let’s look at the Fender eras of amp manufacturing:

 

 

Woody: The very first Fender amps were only made for a year and a half. Starting in 1946, they were constructed with a stylish wooden cabinet and came in three models: Princeton, Deluxe, and Professional. These circuits would grow and continue to be the cornerstones of Fender for decades to come. They are small and rather quiet by modern standards, but Fender was able to make a name for itself by producing amplifiers that were reliable and sturdy in a relatively empty market. Needless to say, if you ever come across an original Woody model, you’ll be sticker shocked as they are incredibly rare!

 

 

Tweed: The Tweed era is the true beginning of Fender amps as we know and love them. While still rare, you can find original Tweed models every so often. Most importantly, they sound incredible and, in my opinion, offer some of the finest tones that Fender has ever produced with their products. These amps are lacquered with a fine twill fabric and have a small chrome chassis. Tweed models include the Champ, Princeton, Deluxe, Tremolux, Vibrolux, Bassman, and more. Most of the named models are variations on the same circuit. It’s helpful to think of the amp as building blocks. For example, the Champ is the most simple circuit, and the Princeton is essentially the Champ but with an added tone control. The Deluxe is like a Princeton but with higher wattage output and two channels. The Vibrolux is like the Deluxe, but there’s a tremolo circuit added on. You get the idea.

The most important trait of all Fender tweed amps is that they are simple. Nearly all of them are made with all-tube topography, and some, like the Deluxe, are built with undersized output transformers. Both of these features mean that tweed amps produce the purest, most natural sound of real tube breakup and distortion. If you’re looking for incredible edge-of-breakup touch response and rich tube sound, you can’t go wrong with the Deluxe or other amps in the tweed family.

 

 

Brownface: This era was short-lived, but marks a vital transition from tweed to the powerhouse Fender amps that we love. Built between 1959 and 1963, brownfaces (named for their cocoa brown control panel), offered a few new bells and whistles, pushed the capabilities of volume, and were a bit higher fidelity than their tweed predecessors. Brownface amps are serious performers and can fetch a pretty penny due to their rarity. You may also see them with blonde control panels or Tolex. These amplifiers introduced more negative feedback in the circuit, meaning that they are capable of staying cleaner at higher volumes. They have two channels and independent tone circuits. Fender introduced standalone reverb units that could be piggybacked onto other amps during this period, and later brownface models like the Vibroverb were the first to incorporate onboard reverb. Most existing Fender model names were carried through to the Brown and Blonde faces.

 

 

Blackface: Named for their all-black control panel and commonly matching black Tolex, these amps are probably what you picture when you think of the classic Fender amplifier. They were produced between 1963 and 1968, and plentiful reissues and lookalikes are still made today. All of the models from this era were derived from the AB763 circuit (an internal Fender code for July, 1963). Most amp enthusiasts consider the AB763 to be the pinnacle of Fender’s innovation. Each one included tremolo, reverb, or both, and boasted the loudest and cleanest tones thus far. Midrange controls were added to the tone amps’ tone stacks, and an emphasis was placed on high fidelity, making the blackface era a far cry from the original sounds of the tweed era. An important moment in Fender’s history occurred in 1965 when the company was sold to CBS. Most enthusiasts agree that quality dipped across the board during the CBS era, but vintage blackface amps are largely exempt from this degradation. Silverfaces, however…

 

 

Silverface: You’ve figured it out by now – these amps have a chrome or silver faceplate. This is the biggest era yet and encompasses the time between 1967 and 1981. The last three years of the 1960s covers “drip edge” silverfaces, a unique cosmetic design that varies from the “silver panel” silverfaces of the 1970s. Drip edge silverfaces are the cream of the crop for this era and are only cosmetically different from the blackface era. In my opinion, I find a drip edge amp to be ultra classy and sleek.

In the ‘70s, Fender was well into its CBS occupation. Word had gotten around that the new ownership was cutting corners with quality, and rumor had it that the internal amp components weren’t as good. This isn’t necessarily true, but silverfaces quickly earned the reputation of being cheaper and the “working musician’s amp”. This resulted in them getting beat up, lugged around, dropped, water damaged – you name it. Silverfaces from this era are rife with modifications, damage, and strange tweaks that aren’t original to the design. This is the first time in Fender’s history that their amps received negative public feedback.

Speaking of feedback, the emphasis shifted from unique tone to overall volume. Concerts were getting louder, and CBS altered the AB763 circuit to compete with the newly required decibel output. Silverface amps from this era use an “ultra-linear” circuit, a feature (or a detriment, depending who you ask) that essentially prevents the amp from ever breaking up and distorting. Silverfaces are clean machines and can remain sparkling when pushed to extreme volume. Most players want the natural tube overdrive that Fender championed, but lovers of hi-fi may enjoy silverface amps.

 

 

1985 to Now: Fender was bought again in 1985, and the CBS era was officially over. Fender saw a sharp pivot across the board towards a return to quality. The beloved amp designs of the tweed and blackface eras were resurrected and continue to be reissued to vintage specifications. Upgrades and modifications of the original circuits were (and continue to be) incorporated with the needs of the modern player in mind while never sacrificing tone. Some of the current best-selling amps include the Blues Deluxe, Blues Junior, and Bassbreaker – all derivatives and improvements on the original tweed Bassman circuit.

You’ll see a lot of Hot Rod amps on the used markets, so let’s discuss. Fender made the Hot Rod Deluxe and the Hot Rod Deville, the latter being slightly cleaner and sparkly. They were introduced in the late 1990s and continue to be produced today. These amps are known for their huge output – the volume is enough to peel the paint off the walls. Most players use an attenuator with these models or only use them for big, outdoor gigs. In general, the clean channel for this series is exquisite, but the overdrive channel leaves a lot to be desired. If you’re comfortable getting your distortion tones from pedals and need high volume, these Hot Rod models may be for you.

Fender released their line of Mustang amps in the 2010s and still produce them today. Let me tell you, this is the amp that I wish that I had when I was learning to play guitar as a kid. This is a digital modeling combo amp that includes around thirty presets that emulate the tones of famous amps and musicians. They’re limited in versatility with live rigs – I’d never play a gig with one, but they are loads of fun and sound great in the house.

Naturally, the company continues to innovate and release newer models. For example, Fender recently released the Champion 100, a solid state model that seems to do it all for an incredible price. Of course, all entry and intermediate amps are solid state – but for the bells and whistles that they boast, plus the price, you can’t beat it!

This has been a ton of information, but I hope that I helped clarify some of the mystery and confusion of Fender’s history with amps. To recap, short and sweet, vintage Fender amps sound incredible but are extremely expensive. Modern reissues and custom builds can produce the vintage circuit sound for a fraction of the price. Fender amps made through the 1950s up until 1968 are the pinnacle of design, but your mileage may vary with models made through the CBS era from 1965 until 1985. Modern models riff on the classic circuits of the 50s and 60s with tone and taste in mind.

Let me know if you have any questions or need advice on your next amp upgrade!

Songbirds Speaker Guide

Amp Speakers: All You Need to Know

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Believe it or not, speakers have a huge impact on the overall sound of your amp and tone. They are the part of your chain that is responsible for transforming electrical signal into actual sound waves. Speakers do a lot of heavy lifting! Here’s some information on how to get the most out of your amp and your speakers.

General Considerations:

If you aren’t quite happy with the sound of your amp, make sure that it is placed appropriately in the room. Most speakers sound best when they are closer to ear level – you can raise them off the floor or tilt your cabinet to get this effect.

In general, speakers should be the last piece of the signal chain that gets an upgrade. If your guitar isn’t great, for example, buying a set of expensive speakers won’t magically fix the tone. Ensure that you love the rest of the gear (guitar, pedals, amp, pickups, etc.) before swapping speakers.

Speaker size has a big impact on overall sound. Twelve inch and ten inch models tend to sound the best for guitar by maximizing richness and fullness, while fifteen inch ones are great for bass. Larger speakers produce and support better bass frequencies.

Before swapping speakers, check that the ones that you have are set up appropriately. If they are producing a hum or not sounding quite right, there may be an issue with the amp. The speakers could also be damaged or plugged in incorrectly.

If speakers sound thin and brittle, they may be out of phase (when using multiple amps or sound sources at once) or out of polarity (plugged in backwards). Check this first!

New (or different) speakers may or may not make a huge improvement on your tone. Proceed with caution. Testing speakers in person and conducting unbiased A/B tests is the only way to know if the upgrade is worth it for you and your set up. Do not trust YouTube or other recordings online. With those recordings, the player in the video often has completely different gear, and the method of recording, like mic placement, can totally change the sound that is produced.

Notable Brands:

As far as great speaker brands, you can’t go wrong with Celestion, Jensen, Eminence, and CTS. In particular, Celestion carries many speaker models that are the gold standard for reliability and great tone. The Celestion Vintage 30s, for example, have been used so ubiquitously over the last several decades that players are trying to branch out and find more unique sounds!

Companies like Mojotone and Weber produce speakers that are made with vintage specs and also sound incredible. These are great options for reliable speakers that don’t carry extra name brand cost. Weber also offers services for breaking in new speakers as well as plenty of customization options.

Like any other piece of music gear, there’s a big vintage market with speakers. Many players swear that vintage sounds better and responds to accents with more finesse, but that’s up to the individual to decide. Depending on the year and the model, the high cost of vintage may not be worth the actual audial return when installed in the amp. The most important value of vintage (or used) speakers is that they are almost always broken in, meaning that the stiffness of the cone has worn off. Speakers that have been used sound warmer and are more responsive.

Impedance:

All speakers have an impedance rating, or how much resistance they present to the amp. Combo amps will have matching speakers installed, but the issue of impedance often arises when swapping amp heads and cabinets. Impedance is an important consideration when dealing with tubes as a severe mismatch can damage the amp. In general, amps should be matched to their speakers with the same impedance rating. This means that a four ohm amp output should be connected to a four ohm speaker, for example. 

Mismatches can be safely accomplished with interesting sonic results, but it’s good practice to never exceed double the impedance rating in either direction. For example, a four ohm amp may do just fine pushing an eight ohm speaker, but connecting it to a sixteen ohm speaker may cause damage.

If you aren’t sure about the rating of your speaker, you can easily measure its impedance by using a digital multimeter on its resistance setting. Place one probe on the positive terminal of the speaker, and the other probe on the negative terminal. It is common for the resistance to read slightly lower than the speaker’s rating. For example, a six ohm read would indicate that the speaker is rated with an eight ohm impedance. A reading of zero ohms or infinite ohms indicates a non-functional speaker.

Speakers and amps that are severely mismatched can still be used together with some simple rewiring! This is most easily accomplished with more than one speaker at a time, but you can also match impedance with only one speaker and some resistors. Check out this article to learn about wiring multiple speakers in series and parallel to match impedance, and read this article to learn how to solder resistors on a single mismatched speaker to match impedance.

Conclusion:

I hope that these tips help you get the most from your speakers! Let us know if you have any questions. Songbirds also has dealer access to Celestion and other speaker brands, so get in touch if there’s a special upgrade that you’re considering!