Guitarlington 2015 – The 4 Amigos Guitar Show in Arlington Texas

Last weekend, I displayed my amps at my first guitar show.  Besides the obvious marketing aspects, I met some great people there.  Although lots of vendors had amps, especially vintage amps, I was surprised that there were only a few other amp vendors there.  There were many choice pieces there, including some ’57-59 tweed Fender Bassman amps.

Daniel manning the Texas Tone booth

Daniel manning the Texas Tone booth

One of the amp vendors was Brown Amplification from McKinney, Texas.  They make heads and speaker cabinets, but not combos.  Since I only make combos, I sent them folks looking for heads and they sent folks to me looking for combos.

The first folks I met were the team from Wathen Audiophile. They make some really choice speakers and amps, but they were mainly displaying their select line of preamp and power amp tubes, all cryogenically treated with their proprietary treatment and selected to their own very strict specifications.  Each individually serialized tube includes its own laboratory test report for Heater vol, Plate vol, Screen vol, Grid vol, Transconductance, Grid Leakage, Plate Current, Plate Resistance and Gain. They were kind enough to supply me with a 12AX7-WCM that I used Sunday afternoon in my Texas 2:10 Special in the V1 preamp stage.  That amp got rave reviews (more on that later).

In the booth next to ours, between us and Warthen, was RBi Music, featuring FRET-King guitars by Trev Wilkinson . I use the Wilkinson compensating brass saddle Tele bridge on my guitar.  I really like those guitars, especially their JD Duncan Jerry Donahue model (my personal favorite) and a beautiful Elise semi-hollow model.  Rick Taylor and I got along well, and I let them test drive guitars on my amps, to our mutual benefit.

I had an interesting conversation about guitar amps and the music scene with Mark Daven of the Guitar Radio Show. Mark’s a great guy, and was nice enough to give me a shout out is his blog about Guitarlington 2015. Lauraine O’Toole from Avalon Multimedia dropped by for a visit and had some nice words for the Texas 2:10 Special.

I also got to meet Kevin Butts at Killer B Guitars.  I had to do this after Mark Daven brought a beautiful Killer B lefty T style guitar over to play through my amps. This guitar not only sounded great, but it was a work of art.  I had to tell the builder how impressed I was with his guitar.

The Texas 2:10 Special

I had three amps at the show – The original Texas Tone 12, the tweed Texas 2-Step, and the Texas 2:10 Special.

Daniel manning the Texas Tone booth

Daniel manning the Texas Tone booth

Although the tube tremolo on the Texas Tone 12 always warms my heart, and gets good response, on Saturday the Texas 2-Step got the most attention.  The ability to go from single-ended Champ to push-pull Deluxe circuits, and easily moving from clean to saturation, brought lots of positive response from listeners.

On Sunday, however, the Texas 2:10 Special was the star of the show.  Two incidents stand out.  A nice lady with a Tone Forge T-Shirt came by to get some brochures, and told me that the Texas 2:10 Special was the best amp in the show.  Late in the day, a very talented Nashville guitarist named Nathan came by, looking for the star amp.  He said he had heard about the amp (Texas 2:10 Special) and had come by to test it out.  He played and played on that amp, covering a variety of styles quite handily, all the while raving about the tone and responsiveness of the Texas 2:10 Special.  Rick from RBi let him play the JDD and Elise, but most of his playing was on my personal Telecaster.  He was most impressed with the amp, and I hope to get in touch with him again when he comes back to Austin.

All in all, it was a great time, and a great showing for my amps.  It’s always good to get feedback from musicians, and it’s extra special to get such positive response from people for whom music is their livelihood.

Bruce

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Why Do Tube Amps Sound Better… or Do They?

Many guitarists, especially those that play rock, blues, or country music, seem to agree that “tube amps sound better”.  Almost all guitarists would agree that given the same rated output power, that “tube amps sound louder”.  A 30W amp tends to sound louder than a 65W solid state amp.  Of course, for some types of music, solid state is the preferred amp, and it’s for very reasons that tube and solid state amps sound different.   A jazz guitarist who is not going to overdrive his amp may like the cleans that solid state amps offers.  A metal guitarist or “shredder” may like the very overdriven tones that solid state amps produce that make them so very different than tube amps.

Why do so many think tubes sound better?  I am one of them.

Here’s why:

Guitar amplifiers are often severely overloaded by signal transients, (THD 30%), especially in today’s world of high output pickups and pedals. Under this condition there is a major difference in the harmonic distortion components of the amplified signal, with tubes, transistors, and op-amps separating in distinct groups.

Op-amps produce strong third, fifth, and seventh harmonics when driven only a few dB into overload.  The resulting sound is metallic with a very harsh edge, which the ear hears as strong distortion. Because the sound may be objectionable, op-amps are rarely operated in their saturated region.  This results in a very clean amplified sound with little coloration and true dynamic range (within the limits of the amp).  This dynamic range is not necessarily a good thing, because of the limits of the rest of the system.  The top end of the dynamic range contains transients, but lacks solid pitch information.  The result?  Clean, but perhaps sibilant and cymbally.  Colorless.  Dull.  Perhaps you don’t want your amp to “color” your sound.

Transistors produce buzz or white noise when severely overloaded, caused by the edge produced by overloading on transients, mostly seventh and ninth harmonics. The ears hear this dissonance as noise. Another factor is a lack of “punch” due to strong third harmonics, a kind of blanketing of the sound. Transistor amps exhibit a strong third harmonic when driven to overload, producing that blanketed sound.  This sound, compressed lack of punch, and strong odd order harmonics, may be what some guitarists are looking for.

Tubes generate a whole spectrum of harmonics when overloaded, particularly the second, third, fourth, and fifth, to give a very full bodied sound.  Tubes also differ from op-amps and transistors in that they can be operated in the overload region without adding objectionable distortion.  A slow rising edge and open harmonics combine to create an ideal sound.  Within the 15-20 dB overload range, the electrical output of the tube increases only 2-4 dB, creating a natural compression.  Since the edge is increasing within this range, the subjective loudness remains uncompressed to the ear.  It is this effect cause tube amps to have a higher apparent volume level not indicated on a volume (VU) meter.

Tubes sound louder and have a better signal-to-noise ratio because of the extra subjective headroom that transistor amplifiers do not have.  Tubes get their punch from their natural overload characteristics.  Since loud signals can be reproduced at higher levels, the softer signals are also louder.  This is the famous “sweet spot” that tube amps exhibit.  Strong second and third harmonics give a feeling of a more natural bass response.

The sweet spot will sound loud clean and full, and exhibit wonderful touch sensitive dynamics that follow the guitarist’s playing dynamics.  Roll back the volume control on the guitar or play softer, and you get the full, rich tone at a quieter level.  Dig in, or roll up the volume control, and now you have that natural, sweet, singing tube overdrive that we love so much as guitarists.  This is why we love tube amps!

Notes on harmonics. The primary color characteristics of an instrument are determined by the strength of the first few harmonics.

  • Odd harmonics (3rd and 5th) produce a stopped or covered sound.
  • Even harmonics (2nd, 4th, & 6th) produce choral or singing sounds.

The second and third harmonics are the most important.  The second, an octave above the fundamental, adds body and makes the note sound fuller.  The third harmonic is a musical 12th.  Instead of making the sound fuller, it blankets the sound and makes it sound softer.  Adding a fifth harmonic to a strong third gives the sound a metallic quality that gets increasingly annoying as the volume increases.  A strong second with a strong fifth tends to open up the covered effect that the third induces (this is usually what we want).  Adding fourth and fifth to this will change the sound to an open horn like sound.

Higher harmonics, above the seventh, give edge or bite to the sound.  As long as this edge is balanced, it will reinforce the fundamental and give a sharper attack quality.  Too much of the higher harmonics- seventh, ninth, eleventh – will give that raspy, dissonant kind of sound.  The human ear is sensitive to the edge harmonics.

The major characteristic of tube amps is the presence of strong second and third harmonics, sometimes in concert with the fourth and fifth.  Remember, a strong second with a strong fifth tends to open up the covered effect that the third induces, and strong second and fourth harmonics help create that singing sound we all love so much in our tube amps.

What makes the Texas Tone 12™ different from a Princeton amp?

Recently, I was showing a new amp build to a friend of mine.  After telling him a bit about the amp, a 14W tweed style combo with tremolo, he rightly asked, “What makes your Texas Tone™ amp different from a Fender Princeton amp?”  It’s a good question.

The Princeton wasn’t in mind when I designed this amp, although I used to play through a mid ’70s Princeton (AB1270 with a 5U4 rectifier), in a band with this friend.  I used the Princeton both in the studio and on live gigs. I eventually sold that amp because I couldn’t get loud enough unless I had my Tele wide open on the bridge pickup, and couldn’t get good distortion unless I was using the neck pickup. Now the Tele bridge pickup wide open is not a bad sound, it’s just not appropriate for every song and every situation.

I often play my Tele with both the bridge and neck pickups together, and I often roll the tone control off a bit, no matter what pickup I’m using.  I like the flexibility.  I couldn’t get either the volume or crunch that I wanted. So, I went home, pulled up a Princeton schematic and did a comparison.  What I found is are some interesting thoughts about amp design.

Leo Fender intended the Princeton to be a student amplifier, using in teaching studios and bedrooms.  Of course, I’ve known many people who have used them on gigs and recording sessions, myself included.  In my opinion, it’s fine for not only its intended application, but for use on small gigs, such as coffee houses, and recording, as long as what you want is clean and bright.

So, here’s a synopsis of the differences between my Texas Tone 12™ and the AA964 black-faced Princeton amp. Compared to the AA964 black-faced Princeton, the Texas Tone 12™ has:

  • Cathode biased power tubes vs. fixed bias. The cathode bias I use is somewhat cooler than a 5E3 (the reference for tweed, low wattage, single 12” combo amps for blues and rock), as I find the tone to be much richer that way, and rich tone is what these amps are all about.  Better living through better tone, I say.
  • No negative feedback vs. negative feedback on the Princeton. NFB reduces distortion and gain, while slightly enhancing treble response by attenuating low frequencies. A feedback loop helps create a cleaner signal that goes into cutoff distortion at a much higher volume setting (which ties in with why I wanted to move on from the Princeton). The cleaner sound of NFB is good for clean headroom (a la black-faced Fender amps), great for country, jazz, and Hi-Fi. I find amp headroom in other ways.
  • A 12AU7 cathodyne phase splitter vs. a 12AX7. The single-triode cathodyne phase splitter is slightly-less-than unity gain (about 0.9), meaning there is no voltage gain (actually a slight loss). The 12AX7 tube triode is a voltage amplifier, while the 12AU7 is a current amplifier, and therefore more suitable to cathode follower/cathodyne applications, and can drive more current to the output tubes.
  • The Texas Tone 12™ operates at a higher B+ voltage, and has a beefier output transformer.  Since cathode biased amps tend to have less output power than fixed bias amps, all other things being equal (which they rarely are), the higher voltage level gives me more flexibility to help recover some of that loss while operating at a more reasonable bias than the hot-biased Fender tweed amps. Besides richer tone, the slightly cooler bias leads to longer power tube life. The beefier output transformer has a richer tonal response and more power handling capability.
  • A Jensen speaker that is both higher end and larger (C12Q vs. C10R) than the one on the Princeton. The result is a louder, fuller tone.
  • A subtle and full range discrete Tone control and independent Volume control vs. interactive Volume, Treble, and Bass controls. Easy, full range of tonal coloration and less insertion loss.  It’s not quite as “bright” as a tweed 5E3, although brightness is not lacking.  I get it back in other ways.

Both amps use a grid bias tremolo, although the component values are different and the Princeton acts on fixed bias power tubes while the Texas Tone 12™ acts on cathode biased power tubes. As far as the tremolo goes, everyone who has played or heard this amp raves about the tremolo.

The combination of higher voltages, a 12AU7 PI, reasonable cathode bias, no negative feedback, a beefier output transformer, and a larger, louder, full-range speaker enable the Texas Tone 12™ to be amazingly dynamic and touch responsive, while the single Tone control allows the simple freedom of varying the amount of warmth or sparkle. When the University of Illinois Physics department did an analysis and upgrade of a Weber 5E3 kit, they found that, after their many mods, “the sound of the amp was great, but in many instances the amp without the feedback loop sounded more interesting.” They go on to elaborate. I concur.

Better living through better tone.

Tremolo

I like tremolo.  I like the way it sounds.  It sounds great on a Rhodes piano and it sounds great on a Fender guitar.  It’s a great effect, and used on lots more songs that just Crimson and Clover.

Leo Fender added a tremolo effect to his guitar tube amplifiers in the 1950s with the introduction of the Tremolux and Vibrolux amplifiers.  For some reason, marketing perhaps or a misunderstanding, Leo often called his tremolo effect a vibrato, and he refereed to his vibrato arms on his guitars as a tremolo.

Just to set the record straight, tremolo is the varying of the amplitude, or volume of a sound, while vibrato is variance in pitch.  The “Fender Synchronized Tremolo” on a Stratocaster is a vibrato effect, while the “Vibrato” on Fender blackfaced amps is, in actuality, a tremolo effect.
 
The first guitar tube amp tremolos used what’s variously knows as “bias wiggle”, “bias vary”, or “grid bias” tremolo.  This is what my amps use.  Later amplifiers used different, more complex, or more advanced tremolo circuits
 

Grid Bias Tremolo

A 12AX7 tube triode high gain stage (one triode half of a dual triode 12AX7) is normally used as a low frequency oscillator (LFO), as high gain is a requirement for the LFO to work. (The other half of the 12AX7 is often used as the phase splitter for the push-pull output section.)  To produce the oscillation, the output of the tube is fed back to the input after being processed by a series of capacitor/resistor (RC) taps- three capacitors in series, with a resistor to ground after each one.   Each RC filter produces a phase shift, and cascading them in series causes the gain stage to go into an oscillation.  There is often a footswitch to lift the ground of the circuit, which turns it off.
 
By carefully selecting the value of the resistors and capacitors, the designer can set the speed of the oscillation.  Typically, tube amp LFOs have a base rate of anywhere from 1 to 12 cycles per second.  (A tremolo rate of between 4 and 6 cycles per second seems to be the most pleasing to the ear.)  One of the resistors is usually a potentiometer that is used to vary the speed of the oscillation.  When playing guitar through a tremolo, 1 cps is really slow, whereas anything above 3 cps is pretty fast.  Sometimes you want that really slow, relaxed sound, and sometimes you want that fast warbly sound.  It depends on the style and the song.
 
Once the LFO is built, we have to find a way to use it to vary the volume of the amp.  The “bias wiggle” version takes a tap off the LFO output, runs it through a DC blocking capacitor, and then to a potentiometer that is used as a Depth or Intensity control.  The output of this is fed to the grid bias of the output tubes.  The effect of this oscillation on the output tubes bias voltage is to cause the gain of the tube to fluctuate, and, voila, we have a volume-altering tremolo, where we can control the speed and depth, and click it on or off with the step of a footswitch.
 
This tremolo is lush, warm, and pulsing, a “hypnotic slam effect”. And everything was fine.

Photo-Cell Tremolo

However, Leo was a tinkerer, and always striving to make things better.  If the coupling capacitor were to fail, and high voltage DC was introduced into the grid circuit of the output tubes… well, bad things could happen, like blowing out the tubes or even transformers.  Leo wanted to isolate the LFO from the grid circuit.  He did this by using a lamp and an optocoupler (light-dependent resistor).  The LFO voltage was used to turn a lamp on and off, and the optocoupler then effected the grid bias of the preamp circuit.  This had the desired result of isolating the high voltage from the grid, but it changed the sound of the tremolo.  The optocoupler was more of an on/off switch than a variance, taking away some of the lushness.  Still, many like the deep sound of this tremolo. The parts count and cost was still low, and while it was great for a Princeton or Deluxe, but Leo wanted something better on his higher end professional amplifiers.

Harmonic Vibrato

His solution was a completely new design.  In a 1958 design R. H Dorf patented “a combined tremolo-vibrato system for use in an electronic musical instrument.  Mr. Dorf used an LFO to control the input of his vibrato triode, and the bias of his tremolo triode, and used high- and low- pass filters to prevent sub-audible tones from reaching the power amp, and to keep his effect of the bass notes. 

imageThis design, that “divided signals into components of equal magnitude and opposite phase,” was one influence on what Fender called the “Harmonic Vibrato”. 

This multi-tube circuit split the high frequencies from the lows, and then separate out of phase LFOs for the highs and lows.  The highs were becoming louder while the lows were getting quieter, and vice-versa (see drawing below).  This produced a very rich and lush tremolo that people still argue about- whether or not this effect produces a phase-shifting pitch change, a vibrato. My best answer at this time is that the swirling effect of the highs and lows isn’t a true vibrato, but when it reaches our ears the changes in intensity of the highs versus the lows can be interpreted as an apparent pitch change, when it really isn’t a pitch changing effect.

image

The Digital Age

I have a DigiTech RP-150 multi-effects pedal that I like very much. It uses the modern digital technology – effects on a chip –that’s used in most modeling amps.  I use it with headphones for practicing, often with the built in drum machine.  I connect it via USB to my computer, and play along with music recordings, or I use it to for recording tracks.  I’ve also used it live on numerous occasions.  One of its many effects is tremolo.  I used this to add a tremolo guitar track to a song that we used at my oldest daughter’s wedding for the father-daughter dance.  I bought the mp3 from Amazon, and then used my RP-150 and Audacity to add a tremolo guitar track.  The results were very pleasing.

I also built a transistor tremolo foot pedal to add tremolo to my Palomino V-16 amp for playing live and recording.  It sounds pretty good, and and gives a nice pulsating tremolo tone.  I used it every time we played Bob Dylan’s Everything is Broken.

Sometime after I built my first tube amp, with tremolo, I decided to do an A-B-C comparison.  I had been told by professional guitarists that my old-fashioned grid bias tremolo sounded very good, and wanted to put it up against my other tremolo effects. So, I did.

I hooked everything up, and played them one against each other.  Third place? The digital tremolo.  What sounds great on a PC or in headphones or in a recording environment, is not necessarily what works live.  See my post on why you can’t sound like your favorite guitarist. Second place?  The tremolo effects pedal that uses transistors.  The sound is more organic, more rich.  The clear-cut winner though, was the real tube tremolo.  Oh, my nothing beats the real thing, baby!

There is a richness, a depth, a feel, to tube tremolo that just can’t be gotten any other way.  Just as a good tube amp will be rich with a dynamic touch responsiveness to go from clean to crunch just by varying your right hand on your guitar, tubes give a rich tremolo sound that approaches the swirling sound of a rotating speaker.

This is why I build my amps the old way.

Conclusion

While tremolo was the first on-board guitar amp effect, and went out of favor in the late ‘70s, to be replaced by distortion, it’s still a widely-used effect, that can have a very pleasing effect to the ear on the right song.  Whether a slow ballad or a jazzy up-tempo number, a little tremolo can add a nice touch.

Tuning Your Sound – Speakers

Some people consider amps to be appliances; I’m not one of them.  They claim that your sound comes from you and your guitar.  That’s true, up to a point.  Without the amplifier, no one is going to hear you or your electric guitar.  Without a speaker, no one will hear what you, your guitar, and your amp, produce.

Just as tires are the most important safety feature on an automobile, the speaker is a key ingredient of your sound.  Many tube amp players “roll tubes” – change tubes to get a “better” sound.  Perhaps that money would be more well spent by choosing the right speaker for your needs. The sound coming out of the speaker is what people actually are hearing.  To neglect the speaker is to discount the final, and vital, link in your sound chain.

My first amp had an Eminence OEM Fender Special Design 12” speaker, the one that comes standard on many Fender tube amps.  It sounded good.  Nice, rich tone, with lots of chime.  I loved the tone, but wanted something a little louder to make up for a lack of headroom in a ‘50s tweed style guitar amplifier.  After much research, I selected an Eminence Cannabis Rex.  According to Bill M,, the Fender Blues Jr. expert, the Cannabis Rex is “very efficient, one of the loudest speakers you can put in an amp, and it pushes out pretty, round bass notes really well.”

After installing the new speaker, not only was the amp louder, the difference in tone was startling! It was almost like getting a different amp.  While changing from a JJ 12AX7 to a Tung-Sol to a Mullard to an Electro-Harmonix may produce a noticeable change in tone, changing to a different speaker will most definitely produce a change.

Please note that the amp still sounds great, and I always get compliments on the tone.  It does sound different than it did before.  What was gained was loudness, more bass, a more full tone, and the highs are still crystal clear.  What was lost is that chimey sound.  While louder across the spectrum, the Cannabis Rex has a less pronounced midrange dip and high end peak, and more bass, and it doesn’t have that double high end peak of the vintage Fender Special Design.  As Bill M states, “This is the warm/clean jazz speaker!”

If there’s something you don’t like about your amp, or you want it to sound different, instead of spending $60 or more on new tubes, research a different speaker.  One of the best resources I’ve found is on the BillMAudio website speaker comparison.  He compares the Fender Special Design (Eminence) with speakers from Jensen, Weber, Eminence, and Celestion, giving good descriptions of the various speakers’ attributes.  His advice is that the speaker should be the last mod, after you have tweaked your amp for best tone.  I come from a standpoint that your amp already is working fine.  Maybe if you start with the right speaker, you won’t need to mod the amp so much.  You have to make that decision yourself.

Are You Sure Leo Done It This Way?

Leo Fender was a tireless innovator, and his tube guitar amps set the standard for the industry that continues today.  Many companies make clones or clone kits of classic 1950s and ’60s Fender amps; many try to be exact copies.  Most current production tube amps use circuits based on, or very similar to, those that Leo Fender tweaked over half a century ago.  Of course, tube circuits predate Leo’s amps, and he paid license fees to Western Electric on many of those 1950s amps for using their circuits.  A triode preamp circuit is a known quantity, and there are only two or three different variations of the basic stage one preamp.  The layout is one thing, it’s how you voice those tube preamp and power circuits that shape the tone or sound of the amp.  But what about the components of the amp build?  Do you need “vintage” components in a vintage-style amp?

Carbon Composition Resistors

Many boutique amps and vintage amps and kits use carbon comp resistors. Why?  Well, that’s what Leo used, and those amps have that long sought after sound.  Modern resistors are carbon film or metal film, and most modern amps don’t sound like a tweed Deluxe or Bassman.  Leo didn’t use those, and many people want the look and sound of a carbon comp resistor, because that’s what the vintage amps had.  But, wait a minute, there’s more to it than that.  Do carbon or metal film resistors sound the same as carbon comps?

What does a resistor sound like?  Nothing, unless you drop it on a hard floor in a quiet room.  Tube amps are built on basic math- multiplication and division.  Current equals Voltage divided by resistance.  Put a 100,000 ohm resistor on that 300 volt DC supply and it works out to 0.003 Amps, or 3 milliamps (300 / 100,000 = 0.003).  So, what’s the difference between a carbon comp 100K 1/2 Watt resistor and a 100K 1/2 Watt carbon film resistor or metal film resistor, and what are the assets and liabilities of each one?

Carbon comp resistors look cool.  They’re brown with colored stripes around them, and they look (and perform) just about exactly like those ones in Leo’s 5E3 tweed Deluxe or 5F6A Bassman, so they must be good.  Leo used them (so did other amp builders of that era).  OK, so why did Leo use them?  Here’s a real shocker.  He used them because it was what was available, and the price was right.

Carbon comp resistors have know qualities.  Among these are poor stability, with at best a +/- 5% tolerance, and it’s usually wider than that.  They will change value when stressed with over-voltages, and if internal moisture content (from exposure for some length of time to a humid environment) is significant, soldering heat will create a non-reversible change in resistance value.  Outside of guitar amps, they’re rarely used because modern resistors have better specifications, such as tolerance, voltage dependence, and stress. Carbon comp resistors also cost more today than carbon or metal film.

On the other hand, carbon film resistors have a working voltage of up to 600 volts, and have operating temperatures of -55C to 155C (-67F to 311F).  If your amp ever gets that hot or cold you will have other issues besides resistor performance!  Metal film resistors typically have a 1% tolerance, and possess good noise characteristics and high linearity due to a low voltage coefficient, and they’re very stable.

I like to use rugged MIL-SPEC, low noise, 1% tolerance, high temperature, 500V metal film resistors.  I also use commercial metal film and carbon film resistors. I use some carbon comps, but mostly to satisfy the desires of vintage amp buyers, not for any performance reasons.  The way I see it, if Leo Fender was alive today and building amps, he would use 1/2W carbon film resistors in his amps, because they are the lowest price resistors that have the right electrical and mechanical characteristics.

Cloth Wire

Old Fender amps and guitars (and most old amps and guitars) used this cool cloth covered wire.  Why?  Pretty much for the same reason that they used carbon comp resistors. It was cheap, it had the right characteristics, and it was what was available.

Today, we have much better wire. We have silver-plated, MIL-SPEC aerospace grade, Teflon coated, 600V, 200C wire.  It’s easy to work.  It’s flexible yet holds its shape, it takes solder well, and is small diameter, which is helpful in a cramped chassis.  It’s also pricey.

Less costly is the MIL-SPEC Tefzel coated, tin plated wire. It has similar ease of solder and work characteristics of the Teflon wire, is rated 600V, 150C, and is about half the cost of the above named Teflon wire.  We also have high-temperature MIL-SPEC PVC wire, which has many characteristics of the Teflon wire – takes solder easy, easy to work, small diameter, and is rated 600V, 105C, for about 1/3 the cost of the MIL-SPEC Teflon wire.

There is a new cloth wire out for those who prefer the vintage look.  After all, you may want to show off the wiring in your amp.  This has a cotton cloth braid over a 600V, 105C PVC insulated wire. It’s much easier to work with that the old-style cloth wire, and has superior performance characteristics to the good PVC wire, although it’s still not as easy to work with as the Teflon or standard PVC wire.

Use the new cloth-covered PVC if you absolutely must have the look of cloth wire in your amp, otherwise use a high temp PVC, Teflon, or Tefzel wire.  It’s also the same price as the aero-grade Teflon wire!  Don’t use any PVC or other wire that’s rated less than 600V or 105C.  85C wire has no place in a guitar amp.

Capacitors

I’m not sure I want to open this hornet’s nest, but here goes.  Capacitors are used as power supply filters (to reduce AC ripple in the DC power supply voltage), to block that same DC voltage from the AC signal path and couple tube gain stages together, and to bypass tube cathodes so that the amp gets the desired sound and gain.

Many of the capacitors Leo used aren’t available today.  Electrolytic capacitors are used as filter and bypass caps, and the ones we have today are very good. I use high quality European made electrolytics.  The controversy comes in when people talk about coupling caps.  The ones that Leo used aren’t made anymore.  No surprise.  There are lots of things from the 1950s that aren’t made anymore, and in spite of nostalgic dreams, much of what we have today is better. Televisions today not only outperform the old tube sets, they cost less.

Some companies today sell very expensive vintage style capacitors, and lots of people buy them.  You can easily find $120 .022 tone caps for you guitar, but a $0.79 Radio Shack ceramic disc will give you the same sound. The only signals that go through tone caps is shunted to ground!  You never “hear” any of the signal that goes through the tone cap.  One company makes vintage size electrolytic caps that are nothing more than a modern small size cap placed inside a larger container! They cost more, of course.

I like to use high quality Mallory 150 coupling capacitors.  Mallory 150 has always set the standard for top quality metalized polyester film, high voltage axial coupling capacitors, and that’s what I like to use.  I use high quality ceramic disc capacitors in tone and oscillator circuits.  I tend to stay away from orange drop polypropylene types.  These caps came into guitar amps in the 1960s, and are the heart and soul of the 1970s CBS Fender silver faced amplifiers.  They’re very stable, that’s the good part.  They were cheap in the ‘60s and ‘70s.  They’re stable and cheap and that’s why amp builders used them, not because they had superior sonic characteristics.  If you can find one, look up an old TV repairman and ask him if orange drops give a TV a better picture that a metallized polyester cap.  He’ll probably look at you as if you’re totally nuts.

In Summary

I build vintage-style amps.  To my ears and to the ears of those that play and hear them, they sound very good.  They have that vintage amp sound- the breakup, the tone, the dynamics, and the touch-responsiveness that make those 1950s tweed amps so much revered.  I get that sound by tweaking the component values while using modern high-quality components that offer better characteristics than the old-style components.  I don’t get that sound using vintage style carbon comps, orange drops, and cloth wire.

If you want the old-school components, I’ll make it that way.  It will certainly make it more “vintage”… and it will make it more expensive.

Point-to-Point Wiring?

Recently, I saw on a boutique guitar amplifier maker’s website that his amps feature “point-to-point wiring”.  I doubt it, and I don’t think you would want it if it were true.  Leo Fender did us all a favor when he dumped point-to-point wiring and started using tag boards in his amps.  In the 1950s, Fender amps earned a well-deserved reputation for serviceability and reliability, so much so that an amp could fall off of a touring bus or pickup truck bed, or be pulled out of a wrecked car, and still work.

What Leo did in his narrow panel tweed amps was to mount his components on sturdy boards with solder grommets for the passive components, and then he mounted the entire amp chassis to the top of the amp, with the controls facing up and the components facing the back of the amp.  Simply by removing the back panel, all electronic components were accessible, with the exception of the power and output transformers.

An amp that is wired point-to-point does not use any type of board for mounting components.  Resistors and capacitors are attached directly to potentiometers, switches, jacks, and tube sockets, and use flying wire leads to connect to one another.  It’s a rat’s nest of wires and components that makes servicing a real pain in the neck, and subjects the components to un-needed stress.  Here is a photo of an old amp that features point-to-point wiring:

point_to_point

I think you’ll agree that it’s a mess, and that troubleshooting or servicing would be difficult, and many components are unsupported.

On the other hand, here are two very nicely done tag board amps, the first a Champ-like build, and the other a Marshall type build:

LilDawg12

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As you can see, the tag board amp circuits are easily traceable for troubleshooting, and the components are all supported by sturdy boards.

It’s for reasons such as these that I choose to use tweed-style cabinets and tag or turret boards in my own amp builds.  My amps are hand wired, but do not feature point-to-point wiring; they feature tag boards or turret boards.  All connections are hand wired, and all component leads are bent and soldered by hand using high quality solder for a sure and lasting connection.