Does Size Still Matter?

Take a look at the photo below and if you look close you can see the relative sizes of the speakers in each cabinet behind the grill cloth.   The one on top is 8″ in diameter and the one on the bottom is a 15″.    Common sense would seem to suggest that one could draw some conclusions just based on what you can see in the photo.
sizeAnd chances are, you’d be wrong.   The little cab actually will reproduce a lower frequency than the big one and the two cabs are actually pretty close in how loud they will actually play. When people see the little cab, they invariably think it’s almost a toy.

I spent much of my working days in the consumer electronic industry including working for a speaker manufacturer in the 80’s, so I know speaker size is also a “big deal” in that world.    Speaker size is also as much as a marketing concept as an actual physical one.    Back in the 80’s, it was common to see a speaker described in advertising as a “12 inch three way” or a “10 inch two way”, along with some low price indicating Value for money: as if the speaker size and number of drivers were primary considerations.

50 years or so ago, when I first started playing electric guitar, I quickly learned to equate speaker size with quality.    Look at the 1966 Fender Line up and you went from the Champ, which had an 8″ speaker, to the Princeton, which featured a 10″, then up to the Deluxe which had a single 12″ speaker.    Some models had two (or even four) speakers and then you also have the Piggyback series of amps (with a separate sealed cabinet) that went on up to the top of the line Dual Showman with two 15″ JBL speakers.   Along with bigger speakers, the amps also had more power as they got more expensive, so there was an obvious corollary between speaker size, amplifier power and quality.   Not only would the top of the line amps play louder without distortion and have deeper bass, but they would also “sound better”.

Over the years, I’ve owned examples of most styles of guitar speaker and cabinet: open back combos with single 8 speaker, single 10, single 12, dual 10’s, dual 12’s, and four 10’s, and as you can see in the photo, a single 15.   I’ve had sealed cabinets with single 10, single 12, dual 10’s, dual 12’s, and four 12″.  Whew.

But, prior to a couple of weeks ago, I’ve never used a single 8″ speaker in a sealed cabinet.    My previous experience with an 8 has been limited to several example of a Fender Champ.   I always thought of a Champ as a practice amp, or maybe something to record with, but never gave much thought to using one on stage playing with a drummer.  I posted a blog post a few years ago about my experience with a Champ, although I entirely missed the role the smaller speaker played in my enjoyment of it.

A couple of years ago, I played through a Quilter amp that, unbeknownst to me, had a 8″ speaker, specifically the Celestion TF-0818.    I noticed that it sounded pretty full for such a little amp, but I was more focused on the guitar I was playing through it.  I WAS also a little surprised that it was also a solid state amp design.   It was also a $900 amp, as well, a price that would purchase any number of other amps with “real” guitar speakers in them——-

I started reading favorable reviews of quilter products and when they came out with the 101 Mini head for $299, I figured I could pair it up with one of a number of speakers and  cabs I already owned, and thus try it out for little financial risk.

I have mostly been happy with the results of running the 101 into a couple of 12″ cabs with various speakers.    I read a couple of posts on the Quilter Facebook forum about people taking existing 8″ sealed speaker cabs and fitting higher quality speakers in them.   I also listened to a few clips and read positive reviews about the MicroPro with the 8″ Celestion.

So, now I have the little cab you see in the photo, which now has a Celestion FT-0818 speaker inside.  My total investment in cab and speaker is under $120.  It weighs 14.3 pounds.   I’ve mounted the 101 on my pedalboard, which also weighs around 15 pounds,  so I now have a rig that I can easily carry into a club in one trip with a couple guitars in gig bags on my back.  Sweet

entire rigI’ve discovered that it has more than enough power to use a band rehearsals and since I usually turn things up louder in the garage than I do on stage, (proximity of the drums in a small space) once the band starts gigging again (new lead singer) It will work there as well.

I REALLY like the sound of it.    I particularly like the way chords and arpeggios sound with it.  The string to string balance is superb and it has unusual clarity.   It also goes down lower in the frequency spectrum than any of my other speakers, including that 15″ in the photo.

To be clear,  this bass is there because of the sealed cabinet and the other speakers at my disposal seem capable of playing at louder volumes than the Celestion with the bass cranked, although I don’t actually do that in practice.  But set a microphone in front of the cab, and you’ll hear it produces more bass than the open back cabs do, as you will probably have to adjust EQ to deal with that.   I used the controls on the Quilter to reduce the bass to suit my preferences.

The other thing that is noticeable is the relative lack of “beaming” or directionality compared to other sealed enclosures I’ve used.  You can put it right on the floor and yet walk right up to it and practically have to be standing on top of it before you hear it start to sound muffled.   At band practice, I set it up where I usually have a 12″ cab which I have to tilt it up to hear the full spectrum out of it.  I don’t have to do that with the Quilter.    It still doesn’t quite have the spaciousness of an open back cab, but the dispersion is wide enough that the sound is bouncing around off the walls, ceiling and floor a lot more intensely than it does with a larger speaker in a sealed cab.   The sonic difference between open and closed back cabs with a speaker this size would seem to be much less: so it also might be less “objectionable” to folks who prefer open back cabs with larger speakers.

It might be helpful to look at a couple of charts to explain why some of the differences between speakers exist.  Below, find Frequency response curves of both the Eminence Texas Heat 12″, and Celestion FT-0818 8″ speakers.
texas heattexas heat vs celstionIn addition to this information, this little table might come in handy:
guitar-tableFirst off, it should be stated that these figures were obtained with the speaker installed in a flat baffle and measured with a microphone at a distance of one meter.   Installing the speaker in an actual cabinet will have a large impact, particularly in the area below around 2-300 Hz.

A sealed cabinet of the correct volume will allow the speaker installed in it to reach lower frequencies than one installed in a cabinet with an open back.

Further, all speakers tend to become directional when the wavelength of the the frequency the speaker is producing becomes shorter than the diameter of the speaker.  A 1,000 Hz wavelength is about 13.5 inches long and 2,000 Hz is about 6.5 inches.   This explains why the little 8″ driver has better dispersion than a larger driver in a sealed cab.

An open back cab will disperse some of the energy out the back of the cabinet, which will lesson the directionality somewhat, but is unpredictable, depending on what is behind the cab: curtains, glass, a brick wall, nothing, or more likely a drum set.   Also, multiple drivers in a cabinet, such as a 4 X 12″, will also couple and act much like a single large speaker, with directionality starting at an even lower frequency.

It should be clear that the frequency response characteristics of the two speakers are most different above 1,000 Hz, aside from a slight rise in the Texas heat between 500 and 1,000 Hz.   The fundamental frequencies on a guitar neck are virtually  (except for the last three frets on a 21 fret guitar) all below this range.  What differences you hear are going to be largely a matter of harmonics.    Start a blues based solo on the fourth string 10th fret “C” and end it on the “F” on the 13th fret of the 1st string, and your fundamental tones will be between 262 Hz and 698 Hz.  As you move up the neck, more harmonic information moves you into an area where the Texas Heat is becoming somewhat non-linear.    Those harmonics will be noticeably louder than they are with the Celestion.  This doesn’t mean the Celestion is better, just different.   One man’s “smooth” is another man’s “dull”.

In my own particular case, I have a suspicion that the extended flat response is part of why I like the Celestion so much.   The guitar just sounds so “clean” and clear and I also hear the progression from clean to dirty when I use distortion.    I’m also noticing that I seem to prefer using the amp’s overdrive instead of stepping on a pedal.

Looking at sensitivity of the speakers, the Celestion is rated at 95 dB (with a one watt input averaged from pink noise response, measured at one meter distance) and the Texas heat is 99.5 dB.   You’ll also notice that for much of the guitar’s frequency range they are only around 3 to 4 dB apart and that most of the difference only begins above 1.7 KHz or thereabouts.   If you look at something like an Eminence Red Fang, (which is rated at 102.5 dB sensitivity) you typically find that it has an even more elevated response at around 2 KHz.

Keep in mind that the test signal is created by a noise generator and it is at the same level at all frequencies.   A guitar signal, on the other hand, is going to tail off as the frequency rises through the harmonic sequence.    By 5,000 Hz most harmonics are barely audible.   The level of power required from the amplifier at these frequencies is going to be considerably less.   The reality of this is that looking at a sensitivity spec and then predicting that one speaker will require 4 times the power to play at the same loudness level is not likely to hold up in the real world.   there WILL likely be an audible difference, and maybe even enough to make you favor one speaker over another, but likely  not as dramatic as the numbers might indicate.

What a speaker will sound like to the audience depends on a lot of other information you won’t find on a specifications chart.   Much of the sound, if not most, is going to have bounced off several surfaces.    A cabinet that disperses well is likely to sound more even through out the venue.   I once had the unsettling experience of standing out on a dance floor with a wireless unit and discovering that my 4 X 12″ had a laser like beam that seemed to be confined to a narrow spot and was delivering a piercing sound suitable of one of those sonic pest control devices rather than the warm, balanced sound I was hearing on stage—–

The 15″ Weber that’s in the amp you see in the top of the page photo isn’t rated for efficiency by Weber, but comparing it to other speakers I’ve had, I’d estimate it to be around 97 dB.  It’s rated for 50 watts input which is about what the amp puts out.   The little Celestion is rated for 100 watts which is about the maximum output of the 101.   For my style of guitar the two rigs have nearly the same level of volume available before they begin to show some signs of distress.  (making sounds I find unpleasant)

I’ve seen comments on various internet forums where people dismiss a single 8″ speaker out of hand as a viable guitar speaker option.  I think the speaker just says “Cheap Practice Amp with No Bass” to them.

Those who play metal are not going to go out and buy one of these, nor are those who like to feel the impact of a loud guitar.    But for those of us who play a moderate levels, a smaller speaker can handle the signal for an Electric guitar just fine.

I know this is an oversimplification as there are all sorts of other factors that come into play here.    I’ve spent over 2000 words here to barely scratch the surface.   I’m hoping the broad strokes will at least give the impression that new technologies have made it possible for guitar amps that are much more lightweight and compact than previously thought possible, that still can perform like, and maybe, in some ways, superior fashion to older technologies…….

A Brief, and Incomplete History of Guitar Amplification

My recent purchase of a Quilter 101 amp head has made me think a lot about guitar tone and how it has “evolved” over the years.    One thing that sticks out to me is that MOST of the amps that have a “signature” tone, achieved that sound mostly by a happy accident.

quilter101I think the first recorded incident of a guitar amp being created with the idea that users would deliberately drive it into distortion was the Mesa Boogie in the late 60’s.   You can see Marshall advertisements in the 1960’s touting “distortion free sound”.

By the 50’s pickups and amplifiers evolved around each other, as did speakers, which in the early amps, were off the shelf items, rather than devices especially created for electric guitar.   None of these devices seemed to be designed with the idea of a “flat response” in mind.    Pickups, amps and speakers were all considerably “colored” and all evolved rather slowly: but everyone who designed a pickup designed it with the idea it might be plugged into some other manufacturer’s amplifier.

That said, the electric guitar never does seem to actually be an attempt to just make an acoustic guitar louder.    Right from the start, you can hear 1930’s and 40’s guitarists driving their amps into distortion and using that capability as a creative tool.      At the same time, the quest for a clear, undistorted rhythm sound lead to increasingly powerful amplifiers.   The Fender Blackface series of amplifiers hit the market just as baby boomers inspired by the Beatles exploded into garage bands, and needed amps.     These amps had a big dip in the midrange response which was a psycho-acoustic slight of hand designed to make the amps seem louder and more powerful.

Since most of the information in a guitar signal is concentrated in the 100 to 2,000 Hz range, “scooping” the mid range area had a HUGE impact on the perceived volume the amp was capable of.       A Fender “Dual Showman” with two D-130F speakers (you could see the bright aluminum cones through the grill cloth) was considered, (at least in my circle of friends) as the ultimate guitar amp.

As Fender was one of the leading amp manufacturers for professional musicians, this sound, however colored was taken as “just how an amp is supposed to sound” to most of us.   All we knew is that those “tweed” amps we saw in pawn shops got fuzzy at low volumes and sounded rather “dull” in comparison.

Looking at these photos generated by the “Tone Stack Calculator”  on the Seymour Duncan page it’s obvious how scooped the mids were on a Blackface amp.     If you look at the photos, you can see the response curves generated by various positions of the tone controls, which are shown to the lower left corner.  Look at the positions of the controls in the photo that shows a relatively “flat” response.  To this very day, Fender is still selling replicas of this series of amps (along with ones that feature “tweed tone”) by the thousands.   They’ve undoubtably sold more “re-issues” of both the black and Silver faced amps than they did back in the day.

Curve FenderThe above photo shows the response curve of a typical fender Blackface amp with all the tone controls set at “five”.  The “scoop” is quite severe, something around 12 dB in this case.

Below is a more typical tone control setting for a black face amp, in fact, this is my starting spot for my own Fender.

curve fender typicalThis one is what one would need to do to the tone controls to get a flat response out of  a Fender amp from this period.

curve fenderflatFinally, a graph showing a rather extreme setting with the treble control turned fully up.

curve fenderextreme

Most Baby Boomers will remember walking into a pawn shop and  discovering lots of old amplifiers sitting around and remember some that were actually painted or dyed black or maybe even covered with black vinyl in an attempt to make them more “modern”.    The period I’m speaking of was the early to mid 60’s and we all wanted to sound like Dick Dale or the Ventures.    When listening to amplifiers in music stores we determined that the ones that sounded the most like a Showman were naturally the best ones.

At this point in time it wasn’t common for rock & roll acts to show the actual guitar amps they were using.  (Also well before the “Guitar Hero” era)   I remember the first time seeing the Beatles on TV with these strange looking amps with a three letter name that I couldn’t quite make out on my parents B&W TV.   (A friend of mine thought they were VOC amplifiers)

Later on in the 60’s and early 70’s, most of the Guitar Heroes seemed to use Marshall amplification.  Most of us know the first Marshall amps were heavily based on the tweed Fender Bassman.     If you look at the control panel on an early Marshall it’s a dead ringer for what you’ll find on a Tweed Bassman.    The amps didn’t sound like the tweed amps, particularly when coupled with two 4 X 12” cabinets with British made speakers in them, but the sound was a lot closer to a tweed amp than a Blackface Fender. Below is a typical Marshall amp response curve.

curve MarshalThe mid bass dip is far less extreme than the Blackface ones.

Below is a typical curve out of a Vox amp.

curve voxVox amps fall somewhere in between and you also have the “Top Boost” option on the AC-30 to add it’s own personality.    The result of all of this is that people usually purchase a guitar amp with a particular “personality” in mind.    Mesa Boogie, Marshall, Blackface Fender, Vox AC series, Tweed Bassman all conjure up sonic signatures of one sort or another.   It’s not at all like purchasing a PA or Hi-Fi amplifier where the standard is fidelity to reproduction of the original signal.    A guitar amp is seen as a tool for the production of sound, as important as the guitar itself in determining the overall sound and many guitarists “play the amp” as much as they play the guitar.

The above is a huge oversimplification with all sorts of factors one can’t account for by frequency response alone.  We’re just isolating one factor.

Obviously, the above response curves are then added to the ones generated by the pickups and further on down the line by the speakers they run through, effects used and even the cable the guitarist is using to connect his guitar to the amp.  And on top of this, every guitarist has his own tone to add to the equation.   Plug Carlos Santana into Eddie Van Halen’s amp and he’s still going to sound like Carlos.

Introducing a new amp head in today’s market is a rather brave proposition as it has to sound like other guitar amps, particularly TUBE guitar amps in order to fit into the signal chain that’s been developed for use with those amps.    Indeed, Quilter has provided a “Voice” knob on the 101 to emulate the sonic signature of several common amp sounds: “Surf”, “Tweed” and “Jazz”.  They have accomplished this to a degree that would seem to be regarded as a breakthrough.

I’ve been using the Quilter for a while now and it is a veritable “swiss army knife” able to get most of the amp tones I regularly use and some I’ve not been able to make previously.

The Trunkslammers, (the band I play with) only do a couple of covers, so the Quilter works well for me, I only have to sound like me.    Once I convinced myself the amp sounded “tube like” I relaxed and started to explore the wide range of tones that ARE available.  The amp’s lack of a “sweet spot” that most tube amps have where they sound best and the fact that the distortion level is totally independent of the amp’s volume give one  a big advantage that the tube amps I’ve owned don’t have.

On the Quilter Facebook page, there have been posts from people who are not satisfied with some aspect of the 101’s performance.    I would be amazed if this was NOT the case, given the amazing variety of guitar amp sounds out there and all the possible combinations of guitar, pickups, speakers and cabinets, not to mention a range of tastes.   The odds of making all guitar players happy are not too great.

When someone purchases a Fender, Vox, Marshall, Mesa Boogie or Dr. Z amplifier, it’s often done (depending on amp model) with the idea of getting a few specific tones being paramount.    One doesn’t buy a Marshall stack with the idea that it also would be able to sound like a Fender Twin Reverb or a Vox AC30.   While some amps do have a reputation for being versatile, most brands do seem to have certain tones they are associated with.

Given all the attempts of manufacturers to make amplifiers without vacuum tubes sound “like a tube amp” over the last 40 or 50 years, it would seem at this point that arguably Quilter has managed this to an unprecedented  degree with several lines and models on sale.

Sounding “like a tube amp” is only the first stage, and we’ll discover if Quilter is “here to stay” when someone describes an amp as “Sounding like a Quilter”.