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…….