Frank the Tech Guy

Ordering your Effects Pedals

Oct 102011

In my daily work I receive a number of questions about the proper order in which to interconnect effects pedals – which ones should go first (closest to the guitar), which ones go last (closest to the amp), and which ones fit well in the middle.

Well, it must be said first that there is no definitive answer to this question, and neither should there be. Getting that unique and original sound is often about breaking the rules, rather than following them. However, this article provides a suggested order, and some explanation as to why that arrangement seems to work properly. However, the most important judge of whether your effects are in the right order would be your ears. If you like the sounds coming from your amp, then don’t listen to what anyone else tells you. Experiment by putting your pedals in all sorts of weird orders and you may stumble on something remarkably cool. The suggestions here, however, would be a good place to start. Rather than listing every single model of effect available, I have grouped effects into families. These should be recognizable to most guitarists.

As I mentioned, the “order” that we are using starts at the guitar, and ends at the amp. For some reason, most stomp boxes have the input jack on the right, and the output on the left. Therefore when you lay your effects out on the floor, the signal goes from right to left.
The theory behind this order is that first should shape your sound, then introduce effects that add color or modulation into the sounds, and then introduce effects that take away from the sound.

1. Distortion and overdrive.

These should come immediately after your guitar. The tone from your guitar and the overdrive form the basis of your tone. This goes first because you only want to be distorting or overdriving the sound of your guitar. The other effects in your chain are carefully sculpted, and if you distort them, you would end up with mush.

2. EQ and Wah.

Some people like to have an EQ immediately after their guitar, rather then after the distortion. Some people like to have EQ before and after the distortion. In an ideal world you would probably have an EQ after each effect, to fine tune the sound at each stage. In the real world that is not practical. Wah pedals are really a type of sweepable EQ that boost and cut the frequencies of the signal as you rock the pedal. In my experience, the wah pedal works best when placed after the distortion. This seems to be because the frequencies that are boosted and cut are those that contain the frequencies of the distortion. This means you get a very linear sweep, with one particular band of the distorted signal boosted at anyone time. Many people (Jimi Hendrix included) have the wah pedal in front of the distortion. This means you are feeding the distortion with different a particular frequency at any one time. The distortion pedal will react differently to differing incoming frequencies, so you will get a different “color” of distortion tone across the sweep of the wah. However, this seems to give the wah a much more binary, (on or off) feel, with a narrow section in the middle that does most of the wah-ing, and any movements of the pedal either side of that narrow band having little effect.

3. Delay (echo)

Some delay pedals come with reverb built in. Unless you will never ever buy any modulation type pedals, avoid them. You don’t want your delay and reverb to be happening at the same point in the chain. Get a delay pedal and a separate reverb pedal. Now that you have built, shaped, and colored your tone, you may want to repeat it using delay. Delay pedals simply repeat the sound that goes into them a number of times, normally getting quieter with each repeat. You want to have your delay before the modulation, because you don’t want your modulation effects to be repeated. Only sounds before the delay will be repeated. Sounds created after the delay will only be heard once.
Once the guitar tone has been created, overdriven or distorted and “shaped” with EQ and wah, and repeated as required with delay now is the time to start adding color and flair to the sound.

4. Modulation.

In this section, I include phasers, chorus pedals, flangers, and envelope filters. These are all effects that add to the sound. They add color, noise and often volume. These effects need to go after your distortion because if the distortion goes after then, you will then distort the subtlety of the effect. If you have a nice chorus effect for example, adding a lovely shimmer and sparkle to your sound, do you really want to then distort that shimmer and sparkle? Probably not.

5. Noise Gate

The noise gate normally goes near the end of the chain, because it is designed to remove background noise which comes from the electronics in the guitar (if it has active pickups) and in the other effects pedals. A noise gate would be pretty ineffective at the beginning of the chain. My choice is to put it at this point, close to the end of the chain.

6. Effects that take away from the sound

There only seem to be two types of pedals that fall into this category: Tremolo pedals and volume pedals. Tremolo pedals slice up the sound much like someone quickly turning the volume up and down on your amp while you are playing. Volume pedals don’t add volume, they reduce it. A volume pedal on full volume would be the same as not having a volume pedal. These types of effect should come last, because you want the complete sound to be cut. If you put the volume pedal after the guitar, only the volume of the guitar would be cut. The volume of all the subsequent effects would stay the same. This would mean that when you reduce the volume on your pedal, the guitar sound would cut out, leaving all sorts of hissing and whooshing from your other pedals. By having the volume pedal last, you can control the overall volume of the signal going to the amp. The same applies to tremolo pedals. By having them at the end, they cut out all the noise, leaving you with silence in “off” periods. (Assuming the depth on your tremolo pedal as at max.)

6. Reverb

Reverb breaks the rules I’m afraid. I just said that effects that add sound should come before effects that take away from the sound. Reverb is the exception, and I can justify this by imagining what happens to a guitarist playing in a big concert hall without a reverb pedal. (He doesn’t need one, the concert hall provides the reverb.) All the sounds are created and effects are added and blast out of the amp. Then the sounds bounce around inside the hall and get jumbled up. Any silent periods in the music are filled with the sound of the previous section still bouncing around. Therefore to emulate this, reverb pedals go after effects that cut the sound. However, if you want your tremolo and volume pedals to completely cut the signal, put your reverb pedal first.

Note on Effects Loops

The last thing to mention is effects loops. Effects loops are a “send” socket and a “return” socket on the back of your amp. These are normally used to add in modulation, delay and reverb effects. These exist because many people like to use the natural over drive of their amp to get their distortion, and therefore don’t want to line up modulation, delay or reverb pedals before the overdrive happens, for reasons I have already mentioned. The effects loop is a circuit that is in between the actual amplifier in the amp and the speaker, so is similar to having your modulation effects after an external overdrive or distortion device.

So, there you have it … as I said, a starting point. Experiment, and most of all enjoy all of the variations and endless possibilities with your effects pedals. Until next time, I’m Frank the Tech Guy!

“Effective” Use of Effects – Part III

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Jun 132011

Last time we discussed compressors, expanders, limiters and gates – devices that do not make drastic alterations to your sound, but are nonetheless very important. Next, we discuss effects that make “drastic” changes to your sound, namely Gain, Overdrive and Distortion. First, let’s dispel the myth that these three effects are the same thing. Similar, yes – identical, no.

First, let’s talk about gain. Gain by itself is technically not an effect, but is a parameter used to describe the amount of boost in your signal without changing tonal qualities. Essentially, gain is a function of the level of a preamp. Sometimes you will see “gain” as the label on the control of a stomp box or perhaps a channel on your amp. In the purest context of gain, lead players use the gain function to lift their guitar above the other instruments in the band and let it stand out in the mix. You will want to be careful however if you have multiple stomp boxes with gain settings. If you add more gain to every effects box and use multiple boxes at once you can end up blowing your audience out the back wall of the room, as well as drowning out the rest of the band.

Next, we’ll talk about overdrive. Overdrive is also a parameter that you may see on some effect boxes. This is generally described as the warm distorted sound that you get from cranking a tube amp’s volume up. You can change the dynamics of overdrive just by the way that you play. If you play softly on the strings the overdrive does not show up much but if you start to play harder the overdrive starts coming through. This makes overdrive a very dynamic effect. It is a slightly distorted sound that can really add to the overall tone you are looking for in your playing style. So you don’t have a tube amp, and even if you did, you can’t turn it up loud enough in your apartment complex to get the overdrive sound. What do you do? There are stomp boxes on the market today that allow you to get an overdrive sound at lower volumes. I have used the Tube Screamer stomp box and really enjoyed the sounds I got from it. This is probably one of the most widely used overdrive effects units on the market today.

Finally, distortion. Distortion can be one of the most difficult effects to choose. There are hundreds of different distortion effects on the market today and a new guitar player looking for his new sound is going to have a brain aneurysm trying to decide which one to get. What makes distortion stand out from the other effects we have dealt with so far is the fact that there is no standard in distortion stomp boxes. For example, if you buy two different chorus stomp boxes and set the parameters the same, you are going to get almost the same sound with very little variance in effect. Sure, you may notice some subtle differences, but the standards for these types of effects are very close from manufacturer to manufacturer. This is not the case with distortion stomp boxes. Not all distortion pedals are created equally. Distortion can be hugely different from manufacturer to manufacturer, and even from model to model in the same manufacturer’s line. Do not despair. There are some ways to sort through this crazy maze of sound. Let’s break down how to select the right distortion for you.

The first thing you need to do is figure out what kind of distortion you are looking for. This is based on the kind of music you are going to play, whether it be grunge, classic rock, heavy metal, modern rock, country (yes even country has distortion), or any other of the many styles of guitar playing out there. Once you figure this out you are on your way to choosing the right distortion for you. The best way to find your dream distortion is to start weeding-out the ones that are not right for your style.

What is in a name? The best place to start your weeding-out process is by reading the descriptive name on the units you are looking at. For example, if you are a blues or country player you may want to avoid stomp boxes that have words in their description such as “Death,” “Metal,” “Grind,” “Grunge,” “Atomic,” “Nuclear,” and “Atom Splitter.” These are definitely not going to shape your sound to your taste and would more than likely be a waste of time to even check out. Check them off your list. If you are a metal or grunge player you will want to avoid units with descriptive words like “Blues,” “Warm,” “Fuzz,” and even “Overdrive” unless it is preceded by a word like “Death,” “Metal,” “Grind,” etc. Now keep in mind that all the different pedal manufacturers are trying to outdo each other in their descriptions so some pedals may not even give you a clue as to where they fall in this mix. Those you are not sure of, you should check out. By following this simple step of name analyzing you can probably cut your selection process in half or better.

Another way to help in your selection process is to remember that most tube distortions will have a warmer and smoother tone while solid state distortions have more edge to them. This does not mean to discount them for this property, but it is another reference you can use while weeding the less desirables out.

When you get around to trying a different pedal always start with the unity gain control at “0.” This will allow you to hear what the pedal does to your sound without an increase in volume. This is important because you want to hear the pedal’s nuances before you crank it up. This is what will set the bar. Now start playing with the controls and see what you can come up with. Do not change your amp settings for different pedals. Set it up once to get your favorite tone before you start and then don’t touch it. If you do, you will be skewing the results of your testing. The distortion unit should sound good with your clean tone. If it does not sound good, you will have to sacrifice your favorite clean tone for the distorted tone. You need to find something that will work with the clean tone you like to use so that everything sounds good when you are switching between the stomp box in the on position and off position.

Now at this point you have probably weeded out the units that you did not like. I suggest that you make a list of two or three that you really like and one or two “possibles”. If you’re impatient and need a pedal to take home right now, select the one you like best and buy it. If you have a little more patience, I suggest that you take a break for at least an hour or so and go do something else that is away from a lot of noise. I suggest this simply because your hearing degrades over time when being assaulted with sound. If you take a break for awhile you can come back with fresh ears to try your favorites again. This will help you to select the one that sounds best to you.

Wait, what about those of us who play many different styles of music? There are two choices here. You can select a couple of different pedals for the different styles or you can go with a multieffect unit that has a couple of distortion choices – such as many rack-mount units on the market today.

Can you use two distortion stomp boxes together? If you get the tone you want by doing this, go for it. In music, the end always justifies the means when it comes to the tone you like and want to play.

I hope these discussions of effects and how to properly use them has been helpful. Meanwhile, I’m still Frank the Tech Guy – keep on playin’ that music!

“Effective” Use of Effects – Part II

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Mar 292011

Effects
In Part 1 we talked about reverb, delay, chorus, and flange. These are the “echo” or “delay” effects. In Part 2 we will discuss what compressors, limiters, expanders, and gates do and how they can be used. Note that these effects are what we call “control” or “behind the scenes” effects in that they do not intentionally modify the sound for variety or the enjoyment of the listener … rather, they control the basic sound so that it behaves itself. Let’s see what we mean by this …

Compressors:
What does a compressor do? Compression is arguably the effect most misused by guitarists. This misuse is probably because many players do not understand what compression is or what it does. When a new guitar player gets hold of a new effects unit they expect that it is going to alter the sound of the guitar in a very noticeable way. A compressor is not this kind of effect. Think of it as a ghost in the shadow of the effects chain. If you weren’t looking very hard for it you would not even notice that it was there.

So what exactly is a compressor? A compressor is a signal processor that is used to reduce the dynamic range between the softest and loudest parts of the audio signal. Think of the sound of your guitar as a wave. There is a peak where it is at its highest level and a trough where it is at its lowest. Sometimes these highs and lows get out of hand; that is, the highest levels start clipping, and the lowest levels are drowned out and are inaudible in the mix. A compressor reduces the highes and brings up the lows so that your dynamic range is, well … compressed. This stops the clipping of the louder passages and improves the sound while preventing costly damage to your equipment. It also brings out your quieter passages so that the listener can hear them.

Compression can be used on any single instrument or on the mix as a whole. Many bands and studios use compression on vocals because of the dynamic range of the human voice. Very high notes take more power to belt out and will sound louder than the low notes that sound softer because of the lack of power used to hit them. Using the compressor will make the singer have a more consistent range of volume. It also works great for live applications where the singer is constantly moving his head toward and away from the microphone. Bass players use compression to make a smoother-sounding transition between notes.

One of the benefits of compression on a guitar is the longer sustain of notes or chords. As the signal is starting to dip below the floor, the compressor will open up and let more signal through. This will allow the signal to be audible longer resulting in more sustain.

You will need to set up four main parameters on a compressor. These parameters are the compression ratio, threshold level, attack time, and the release time. The compression ratio sets the level of compression that will take place once the signal reaches the threshold. A 3:1 compression ratio would mean that for every 3dB of signal above the threshold there would only be a 1dB increase at the output. The threshold level is the level the signal needs to reach in order for the compressor to kick in and start working. The attack time is the amount of time it will take the compressor to react to the incoming signal. The release time is the amount of time it takes for the compressor to allow the signal to return to a normal level.

There are two main types of compression—hard knee and soft knee. The knee is the moment that the compressor starts to reduce the gain when the signal reaches the threshold. Hard-knee compression cuts the signal off abruptly when it reaches the threshold point. Soft knee is a smoother gain reduction that lets the sound taper off at the threshold point. Most good compressors on the market today let you switch between hard knee and soft knee.

It is very important to understand that compression can be overused and cause your signal to sound flat and weak. Use it with care, experiement with it, and improve your sound. Remember, a compressor is a tool to tweak your sound – use it carefully. Just as seasoning adds to the flavor of a good dish but too much can ruin an entree, so goes compression.

Limiters:
Limiters are quite similar to compressors. As we talked about earlier, a compressor reduces louder signals of your instrument. Unlike a compressor, a limiter completely cuts the signal off at the threshold. It is a great device to save your sound system from hitting levels that can damage or destroy it. It will not let your signal go above the maximum level you set. So unlike a compressor, the limiter is only going to deal with the louder levels of your signal.

Expanders:
Expanders are completely the opposite of compressors. Whereas a compressor is going to reduce your signal into a set parameter, the expander is going to widen that signal within set parameters. Why would you want to do that? An example of the use of an expander would be finger-sliding sounds on an acoustic guitar. Let’s say that you have the finger-sliding sound coming through your mix on the lower end of the audible signal. If you expand or exaggerate the signal dynamic width, it will push this sound further down into the mix so it will not be so pronounced. Another example would be breathing sounds from a singer at the microphone. Again if the signal is expanded it pushes unwanted sounds further down the audible signal. An expander is usually used to reduce unwanted background noise in the mix.

Gates:
A gate works like a limiter but at the other end of the signals dynamic range. A gate cuts the signal off below the set parameters level. Unlike the compressor which pulls the lower level sounds up, a gate chops it off completely. Like an expander it is used to keep unwanted background noise out of the mix. One very common use of gates is miked drums. When the drums are miked up individually, you do not want other drums sounds bleeding into the wrong microphones. The gates cut off the signals bleeding over from other drums and clean up the mix. This is effective in keeping the cymbal sounds from bleeding over onto the tom tracks. It is used most dynamically on the snare drum mic and hi-hat mic because of their close proximity. Gates work well with guitar for eliminating the hiss and unwanted noise heard when the instrument is not being played.

So where should these effects be put in the effects chain?
There are two schools of thought on where to put compression in the effects chain. The first is that it should be at the beginning, so a smooth clean signal hits all of the other effects. I do not buy into this method personally because I know that some effects are going to cause the signal to clip again. The method I like is to put it after all the effects except the echo effects like reverb, delay, chorus, and flange. I want to compress all the effects in the signal but let the reverb-type effects fade out naturally. Both methods work for different people so you will want to try them both and see which works best for you. These methods also apply to limiters and enhancers. As far as a noise gate goes, I like them at the end of the effect chain so they cancel out any residual noise caused by the effects unit, especially flange. Flange has a tendency to cause a lot of background noise when the guitar is not being played.

Next time, we’ll look at Overdrive, Gain and Distortion. Aren’t these all different names for the same effect? Actually, no. They’re similar, but not the same thing. Stay tuned! Until next time, I’m Frank the Tech Guy.

“Effective” Use of Effects – Part I

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Mar 202011

I just want to give you a quick note about effects before we get started. You can’t set up your effects in your practice area and expect them to sound the same in the club this weekend. Room acoustics change the dynamic sound of your effects. Allow yourself plenty of time to set up your equipment and tweak your effects at the club before you start playing. If you don’t do this, you can have a disastrous show and may not be invited back to that club again. Remember that every club is a different room environment. It is best to keep a notebook on how you set up your effects at each club in case you play there again.

Now let’s talk about specific effects.

Echo Effects:

Reverb:
“Reverb” is a good place to start since it is built in to most guitar amplifiers on the market today (and for the past fifty years!). Reverb is an echo effect reminiscent to sound you get when you are overlooking a canyon and can’t resist the urge to shout “hello” and hear it echo back at you. If you want an example of reverb, turn the reverb knob all the way up on your guitar and strum it. Immediately mute the strings with your hand and you should hear the echo reverberate from the speaker.

In the early days of recording reverb was done in different ways. One way was to place a microphone at one end of the room and another close to the speaker cabinet. You would then record the guitar on two tracks and play them back together giving a sort of echo effect. If the effect needed to be tweaked or changed the engineer would move the microphones or speakers around the room until the desired effect was achieved. Another way of achieving reverb is to place the microphone and amp in a bathroom. We have all sung in the shower before and thought we sounded pretty good, right? Bathrooms are small rooms with hard tile walls that reflect sound instead of absorbing it. Weird Al Yankovic recorded many of his early albums in a bathroom.

There are many types of reverbs that you may run across in your search for the best sound for you. Three of the most common are spring reverb, plate reverb, and digital reverb.

Note:
As a general rule of thumb too little reverb is always better than too much. Too much reverb in the mix can make the sound muddy and drown out vocals and other instruments.

Delay:
Delay is probably one of the most valuable effects. It is the building block that many other effects such as reverb, flange and chorus are based on. A delay is basically what the name says. It is a delay of the original signal of the guitar that plays at a set time after the original notes or chord is sounded. It can range from milliseconds to several seconds depending on how you set the time parameters. When set at several seconds you can actually solo over yourself.

Slapback delay is probably the most commonly used and can range from 30 milliseconds to 100 milliseconds.

Chorus:
Chorus is a version of delay and is my favorite effect for clean sounds. Chorus gives the impression of multiple instruments playing the same part. The unit puts a very small delay in the signal and (depending on the amount of delay) it detunes the echo to give the effect that another guitar is playing with you. This effect adds a sparkle and clarity to your sound. Chorus is best and most often used with slower tempo songs.

Flange and Phase Shifters:
Flange was created by accident in a studio. It was found that if you played back a reel-to-reel tape of the guitar track, held up the reel (the flange of the reel, to be exact) with your hand, and then let it go, it would catch up with the other tracks causing what would become known as flanging. The best way I can describe this effect is that it’s like riding a roller coaster. You go up the hill slowly (the engineer holds the reel back with his hand) and when you hit the top you pause for a millisecond and then you rush to the bottom very quickly (the engineer lets go of the reel to let it catch up with where it should be). Then you start up the hill again slowly (the engineer holds it with his hand again) to do it all over again. The other instrument tracks would be played normally and the guitar track would be held up and let go to catch up at regular interverals throughout the track. This created a “whooshing sound” on the guitar track kind of like a jet engine.

Thanks to electronic and digital technology we can reproduce this effect with stomp boxes and multi effects called flangers. Flange moves in and out at a constant and steady predetermined speed that you set.

Phase shifters are like flangers except they have multiple flanges going on at the same time and sometimes with no predetermined speed. Both are great additions to any guitar player’s setup.

A couple of things you need to remember about using effects in general. There are no set rules on how to use these effects. You can use just one or you can use a combination of all of them. While the echo effects are similar in ways they have their own distinct differences that can complement one another in a mix. Play around with them and have fun. You never know what you will come up with.

All the effects I have mentioned have their own parameters that can be adjusted giving you a full range of variations to play with. You can find your own signature sound by using what you like from each one.

Effects can improve the sound of your guitar and sometimes can make you think you are playing better. They can cover small mistakes, but I urge you not to use them for this. That is not the intended purpose of effects. You should be able to play a part cleanly with good technique before you start adding effects. If you can play it clean, it will sound even better with effects.

Note:
If you use compression and gates always put your reverb and delay behind the gates in the effects chain so they fade out naturally instead of being cut off by the gate.

In Part II of ” ‘Effective’ Use of Effects”, we will look at compressors, limiter, expanders, and gates.

Schematic Resources

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Oct 182010

For those of you who do work on your own amplifiers, there are a few resources on the internet which offer schematics for many different makes and models. A few of those include Dr Tube, at www.drtube.com/guitamp.htm, the Free Information Society, at www.freeinfosociety.com/media_index.php?cat=13&subcat=10&start=0, and up until recently Larry’s Schematic Heaven, at www.schematicheaven.com.

Unfortunately, Schematic Heaven seems to have finally made it to heaven, as the website has been down for several weeks now. Fortunately, a new resource for schematics has been opened, and will hopefully be able to reintegrate all of the schematics which were formerly housed on Schematic Heaven.

The new site is part of www.amprepairparts.com and so far has cataloged all of the Fender schematics which were formerly available from Schematic Heaven. The Fender schematics are found at www.amprepairparts.com/fenderschem.htm. There are also a few other schematics available on the site, and the company has promised to try and catalog all of the schematics which were formerly on Schematic Heaven within next few weeks.

If you work on amplifiers, you know how vitally important schematics can be. They are the road maps of the circuit design. Yes, simple problems can be resolved without the use of schematics, especially if the technician is familiar with the particular amplifier … much as you don’t need a road map to drive around familiar roads near to where you live. But if the problem is difficult or unusual, or the technician is not familiar with the amplifier, having the correct schematic is as vital as having that road map for a road trip.

One last thing: www.amprepairparts.com also carries a nice selection of parts for amplifier repair, and the folks there are very helpful. It’s handy to be able to locate the correct schematic for the amp under repair, and then purchase the parts you need from the same website.

Until next time, I’m Frank the Tech Guy. Keep on fixin’ those amplifiers!

Taking care of your PA horns

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Aug 082010

One of the most common equipment failures that I see in my business is the blown horn driver. The diaphragms in horn drivers are fragile, but with a little knowledge and care, they can last a long time. Here are some tips to avoid horn driver failure (and for that matter, sub and woofer failure as well!)

1. FREQUENT OCCURRENCES OF HARD FEEDBACK
If you go “ouch” after that last squeal, chances are so did your speakers! This one is compounded by proceeding to use the speakers after they have probably been damaged. You and/or your sound engineer need to respond very quickly to out-of-control feedback. Consider adding a feedback suppressor to your effects rack.

2. IMPROPER BIAMPLIFICATION: CROSSOVER TOO LOW OR HORN AMP LEVEL TOO HIGH
Always check your speaker specs for the best crossover points. Just look at the model number of your cabinets, or even the model number of your horn drivers, and set your electronic crossover to the crossover frequency recommended.

3. NOT ENOUGH SPEAKER SYSTEMS FOR SPL REQUIREMENTS OR PROPER COVERAGE
Most folks throw “extra watts” at the same speaker complement: add extra channels of amplification in concert with additional speakers. You can’t ask your speakers to produce more than their designed limits. If you bought your PA system intending to play small gigs at small clubs, and suddenly you find yourself booked for a wedding reception gig in a gymnasium, you need to add more power amps and speakers. Consider renting equipment to adequately cover the larger venue.

4. TRYING TO COVER AN OUTDOOR GIG WITH YOUR INDOOR SYSTEM
Outdoor gigs require at least 12 dB (16X power) more sound output than indoors, and as much as 20 dB (100X power!) to really do it right. If you are trying to do an outdoor festival with large crowds, you need a professional sound company.

5. EXCESSIVE EQ
The classic “smile” EQ curve is actually smiling at your speakers imminent demise! Keep in mind that EQs are best used for cutting, not boosting the signal. Need more highs? Reduce the bass…Need more lows? Reduce the highs.

6. INCORRECT USE OF COMPRESSORS/LIMITERS
Excessive compression squeezes the life out of your music AND your speakers! Learn how to use your equipment correctly.

7. NOT ENOUGH AMPLIFIER HEADROOM
Too little power, and amplifier clipping becomes the norm. Clipping spells the end of not only speakers, but power amplifiers as well. Watch your clip lights, and adjust the levels to avoid clipping at all costs. If you can’t get the volume you need without clipping, you are woefully undersized in equipment -see #3 and #4 above.

8. SUDDEN TRANSIENTS WHILE THE SPEAKERS ARE HOT
Turn-off thumps, plugging/unplugging mics, etc. The power amplifiers should be the last item of equipment to be turned on, and the first to be turned off.

9. CLIPPING THE SIGNAL BEFORE IT GETS TO THE POWER AMP
Improper mixer gain distribution, line signal too hot, etc.

10. KEEP USING YOUR SPEAKERS AFTER DAMAGING THEM…
And failing to have the crossover parts checked for damage after abusing the speaker system that way! Let your ears be your guide. If you hear distortion from any clean inputs, damage has likely occurred.

Use these tips, and you will experience fewer PA equipment failures. Until next time, I’m Frank the Tech Guy.

Musicians’ Equipment Damaged by Nashville Flooding

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May 122010

Nashville’s record flooding over the first weekend in May caused over one billion dollars in property damage, which made national headlines. But for musicians in Music City, a lot of the damage is intensely personal – hundreds of Nashville’s top stars, working musicians and tour support company owners lost what will likely be several millions of dollars in gear.

Most of the damaged gear was located at Soundcheck Nashville – a storage rental hub in an industrial park down by the Cumberland River. Owner Ben Jumper said the 160,000 square feet of space he rents out is all flooded and the losses will be in the tens of millions. The storage facility is full of classroom-sized “lockers” used to store gear. National touring musicians based in Nashville use the giant facility to rehearse and store their gear when not on tour.

Keith Urban lost his gear. Vince Gill lost most of his entire guitar collection, including irreplaceable vintage pieces with historic value. A tractor-trailer full of LeAnn Rimes’ road gear was under several feet of water. And Brad Paisley, set to start his next tour on May 21, lost his staging, props, guitars, amps and equipment. The list goes on and on. Literally hundreds of musicians use the facility and store their gear there.

Soundcheck Nashville's Flooding

As you can see from the picture above, the flooding was deep and extensive. That’s a 24 ft box truck parked at the facility, with water up to nearly the top of the cab. The fence and entrance gate are in the foreground of the picture, with a security camera barely above the water level.

Restoring musician’s equipment damaged by floodwaters is a daunting task. Many of the stringed instruments will likely be a total loss. The electronic equipment may be at least partially salvageable. Much of the amp restoration work is being done by Tour Supply of Nashville, great guys who do a great job. Mercury Magnetics, a leading manufacturer of transformers for musical equipment, is offering free refurbishing for power and output transformers damaged by the flood. But the amount of equipment damaged is staggering, and the resources to repair it in short order are overtaxed.

I currently have two pieces from the flood in my shop at Uncle Sam’s Jamms in Louisville – a bass amp head and a direct box. I expect to receive more in the next few days, as musicians fan out from Nashville to other nearby communities with repair facilities who can help restore the music to the Music City.

Musicians and others in the music industry are a close-knit group – we come together to help each other in times of crisis. This is no exception, and Nashville and its community of professionals will get through it. And I certainly don’t mean to minimize the losses felt by all of the affected residents of the Nashville area who lost their homes, businesses and possessions – many, many suffered greatly from this tragedy. They, too, will persevere.

Dating Vintage Fender Amps

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Mar 262010

From time to time, I get questions from my customers at Uncle Sam’s Jamms concerning the age of their vintage amps. The most frequently asked questions concern Fender amps from the 50′s up through the 70′s. In most cases, it’s not difficult to determine the year of manufacturer of most Fender models from those periods.
Fender Vintage Blackface Amp

On the inside wall of your Fender amp cabinet, there may be a tube location sticker which shows the tube layout, model number, production location etc. There may also be some letter date codes rubber stamped on this sticker. These date codes will contain two letters of the alphabet which refer to the year and month of production, and may be interpreted as follows:

Code Year
A 1951
B 1952
C 1953
D 1954
E 1955
F 1956
G 1957
H 1958
I 1959
J 1960
K 1961
L 1962
M 1963
N 1964
O 1965
P 1966
Q 1967
R 1968
S 1969

Code Month
A January
B February
C March
D April
E May
F June
G July
H August
I September
J October
K November
L December

In the absence of the rubber-stamped date codes, EIA numbers taken from the transformers may allow you to determine the date of production of your amp. These numbers always begin with “606″ , and are followed by three or four digits in various combinations. If three digits are present, the first digit would refer the units of the year i.e. (“7″ would mean 1967). If four digits are present, the first two digits refer to the year i.e. (“66″ would mean 1966). The last two digits would refer to the week of the year i.e. (“26″ would mean the 26th week or approximately June). Here is an example: EIA 606-4-21 would mean the 21st week of 1964. It is also advisable to add about 6 months to the date to allow for time these parts may have spent in storage.

There are other methods used to date “Silverface” amps, you will need to get the date codes from your speaker frame, tube chart or pots.

Pots and speakers are usually stamped with a 6 or 7 digit code that can be dated as follows:

The first 3 are the manufacturers code

137xxx = CTS
304xxx = Stackpole
140xxx = Clarostat
134xxx = Centralab
381xxx = Bourns
106xxx = Allen-Bradley

Speaker Manufacturers codes

220xxx = Jensen
465xxx = Oxford

The next number(s) is (are) the year. Initially this was a single digit, latter that was extended to two digits for clarity.

The last two digits are the week of the year. Note that if these digits are larger that 52, it probably is NOT a date code!

Thus a pot with the code of 137634 would be a pot made by CTS in 34th week of 1966.

Note that speakers also use the same type of date code.

Always remember that pots, speakers and transformers may have been changed during a repair!!

For more info, check out these references:

“Fender Amps, the First Fifty Years” by John Teagle and John Sprung
“How old is that Fender in the Window” by Richard Smith
Fender’s web site – www.fender.com

Until next time, keep on playing on that vintage Fender amp! I’m Frank the Tech Guy.

Your UHF Wireless Microphone’s Days May Be Numbered …

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Jan 202010

If you own a UHF wireless microphone in the 700MHz band, you may have only a few months remaining where you can still use it, both from a legal standpoint and from an interference perspective. In other words, it may eventually not be usable due to interference. And if you continue to use one of these microphones, you may be interfering with the new 4G digital communications platforms that are licensed in that frequency band for public safety and first responders.

The U.S. Federal Communications Commission will prohibit hundreds of existing wireless microphone models from being used in the U.S. by June, 2010 because they operate in the 700MHz spectrum band, which was auctioned off to mobile voice and broadband carriers in 2008.

The FCC prohibited electronics makers from selling existing devices that operate in the 700MHz spectrum as of Friday January 8, 2010 in an order issued the same day. Any existing devices broadcasting in the 700MHz band will have to stop operating by June 12, the FCC said.

The main products affected by the ban will be wireless microphones, which have operated without FCC licenses in television spectrum for years. While many wireless microphones operate in lower spectrum bands, and will be able to continue there, the FCC has listed more than 300 models of wireless microphone and related components from 12 major manufacturers that will no longer be allowed to operate in the 700MHz band after June 12, 2010

Among manufacturers listed on the FCC site with wireless microphones operating in the 700MHz band are Audio-Technica, Shure, Sennheiser, Sony and Samson Wireless. Representatives of Shure and two microphone groups didn’t immediately respond to a request for comments on the FCC’s order.

Most wireless microphone systems will continue to work because they don’t operate in the 700MHz band, said Matthew Nodine, chief of staff in the FCC’s wireless telecom bureau. Many wireless microphone makers and users have expected the FCC order since the agency auctioned off the 700MHz spectrum for mobile broadband and other uses in early 2008, he said.

The FCC will try to assist wireless microphone customers with any questions about making the transition to other microphones, Nodine said. Customers may also want to contact their microphone makers, he added. “We’re going to do everything we can to help out customers,” he said.

The FCC has already begun reaching out to people using wireless microphones, and the FCC will conduct an “aggressive” education campaign to reach out to wireless microphone users, the agency said in a press release.

The 700MHz band was formerly used by U.S. television stations, but the U.S. Congress voted in late 2005 to require stations to move off the spectrum and switch to all-digital broadcasts. U.S. TV stations exited the 700MHz spectrum last June.

The goal of the digital TV transition was to free up spectrum for commercial and public safety uses, but the portion of the spectrum dedicated for police and fire departments failed to sell in an early 2008 auction that raised $19.6 billion for the U.S. treasury. Several lawmakers pushed for the digital TV transition after the Sept. 11, 2001, terrorist attacks on the U.S. Many of the rescue agencies that responded to those attacks couldn’t communicate with each other because they were using incompatible communications devices on different areas of the spectrum.

The Public Interest Spectrum Coalition, made up of six consumer and digital rights groups, petitioned the FCC to ban the use of wireless microphones on the 700MHz band.

The FCC’s action will allow “for rapid deployment of new wireless technologies while protecting consumers who bought wireless microphones in good faith,” Harold Feld, legal director of coalition member Public Knowledge, said in a statement. “As a result of this order, more spectrum will be available … in the 700 MHz band for new services.”

The FCC order requires wireless microphone makers to tell customers that the devices operate in television spectrum without FCC approval. These notices will “curtail the previous deceptive advertising practices by wireless microphone manufacturers,” Feld said.

FCC Chairman Julius Genachowski said the commission’s ban on wireless microphones in the 700MHz spectrum was a “necessary and essential action” to complete the digital TV transition.

“Our decision will accelerate the buildout of 4G wireless networks, and will prevent interference with first responders who rely on the 700 MHz Band for mission-critical communications,” he said in a statement.

Nobody likes to learn that a product that they purchased and is still functioning will soon be illegal to operate. But wireless microphones operated essentially free gratis – that is, without licensing – for many years between TV channels in the UHF band. Now that the transition to digital television is complete, the remainder of the UHF spectrum is empty – the only thing that remains is wireless microphones and wireless intercoms in the 700MHz band. Those must be removed as well, so that the spectrum can be designated for emergency communication systems between first responders. The terrorist attacks of 9/11 demonstrated the weaknesses in our emergency communications systems – different agencies were unable to communicate with each other due to different types of radio systems operating in different frequency bands. The transition of 4G to the 700MHz band will allow all emergency responders to communicate with each other – even if they are from different regions and different agencies.

So, now is the time to shop for replacement wireless microphones. Until next time, I’m Frank the Tech Guy.

Bias, Part 2 (Fixed and Cathode Bias)

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Nov 212009

Welcome back, seekers of technical knowledge! (Wow, was that lame or what?) Anyway, last time we discussed the aspects of bias, and how a control voltage on the grid of an output tube in your amp controls the amount of current flow in the tube itself. To recap, this bias voltage acts as a control valve, setting the idle current in the tube at just the right value, so that the tube neither burns itself up by carrying too much current, nor sounds brittle and choppy because it has too little current and is in “cut off” mode.

Our discussion last time focused on the majority of larger tube amps which use an adjustable bias voltage to control the behavior of the output tubes. But a good number of amplifiers use either permanent fixed bias or cathode bias designs. Let’s look at those designs.

Permanent fixed bias is pretty simple, really. If you understand the adjustable fixed bias, then you’ll find that permanent fixed bias is a design which uses fixed resistors to set the negative bias voltage on the grid permanently, rather than offering an adjustable resistor (rheostat or potentiometer) to allow the bias to be adjusted. The advantage of this concept has been heralded for many years by Mesa Boogie, who proclaims that their amps have an automatic bias system that requires no adjustment, thereby making it easier and simpler for their customers to change tubes themselves. In itself, that is quite true – no adjustment needed, and anyone can change the tubes. The disadvantage is that it’s always necessary in a fixed bias design to set the bias on the “cold” side, to ensure that regardless of the characteristics of the tubes installed, the current through the tube won’t exceed the maximum limit. In other words, they have to err on the side of caution. This means that the output tubes response is pretty sterile – by setting the bias cold, the output tubes add very little coloration to the sound of the amplifier – no early breakup, no “bluesy” overdrive. But most Mesa Boogies are crunch machines, and blues isn’t their sound. The overdrive in a Mesa is handled completely in the front end of the amp, by stacking extra preamp stages. The bottom line is that permanent fixed bias is a low maintenance design, requiring no action by the owner. But (and this is just my personal opinion) – you almost might as well have a solid state output, because you’re getting very little in tonal enhancement from the output stage.

Cathode bias is a type of “automatic” bias. It not adjustable, but it’s handled differently than what we are calling fixed bias. Generally, cathode bias is deployed in smaller wattage amplifiers. It doesn’t require a negative voltage supply from the power supply. So … if you’re up on the technical aspects of using a negative voltage to repel and “slow down” the quantity electrons leaving the cathode headed for the plate, you might be wondering how this control can be accomplished without having a negative voltage available? Well, in electronics, voltages are relative to each other. If we can raise the cathode voltage to a moderate positive voltage (say perhaps 10 to 50 volts, depending on the tube), and we then keep the grid at or near 0 volts (ground potential), then the grid looks negative with respect to the cathode. The electrons on the cathode are still strongly attracted to the plate, because it is a few hundred volts more positive than the cathode. But the grid is still a partial barrier to the electron flow, because it is more negative than the moderate positive potential of the cathode. So, as far as the electrons are concerned, they can’t tell the difference – they behave the same as they do in a fixed bias or adjustable bias configuration where the cathode is at 0 volts, and the grid is at -10 to -50 volts DC.

So how do we achieve this positive voltage on the cathode? It turns out that it’s pretty simple. Whenever you force current flow through a resistor, a voltage develops across the resistor, and the polarity of the voltage depends on the direction of the current flow. If we put a resistor of typically a few hundred ohms between the cathode and ground, the current flow through the tube automatically “lifts” the cathode voltage above ground. The final voltage of the cathode depends on the value of the resistor, and can be calculated fairly accurately though the use of some formulas. By choosing the correct value of resistor, the cathode is set at a moderate positive voltage, and a sort of “automatic” bias is achieved.

Cathode bias has a couple of advantages over permanent fixed bias. It offers some compression, some even-order harmonics, and earlier break-up. It also is somewhat self-adjusting, depending on the specific characteristics of the tube installed. To a significant degree, it’s responsible for the warm bluesy tone quality of the old Fender Champs, the Vox AC15 and AC30, the old Silvertone amps, and pretty much any amplifier that uses 6V6 or EL84 output tubes.

So, including last month’s blog, that’s pretty much our discussion of bias in tube amplifiers. Yep, it’s pretty technical, but it’s a necessary, integral part of how the amp works, and one of the important reasons that a particular amp sounds the way it does. Meanwhile, keep on rockin’, and I’ll be back next time with more technical goodies. I’m Frank the Tech Guy.

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