Q. What characterizes a good speaker in a guitar amp?
A. A good speaker produces a tone that pleases the guitar player.

Q. Brithish or American?
A. The terms were traditionally used for the American Fender + Ampeg amps/speakers and the British Marshall + Vox amps/speakers. American speakers were typically Jensen, CTS, Oxford, JBL + while Celestion was the main British speaker manufacturer. Today these terms are mostly used to describe a bright and full tone speaker (American) or a smooth and mellow sounding speaker (British). In our opinion American speakers are best for cleaner sounds while the smoother British speakers tend to match distorted guitar tones well. This is because the smoother speakers reduce the highest frequencies that are produced in a distorting amp.

Q. What does the power rating mean?
A. It says how much electrical power, P = Current x Voltage, measured in Watts, a speaker can handle before it gets damaged. It can get damaged in several ways; the coil wire burns, the speaker cone is teared up or the spider holding the coil in place is torn up or gets misaligned allowing coil rub into the magnet, among others.

Q. Is a powerful speaker louder than a speaker with less max power rating?
A. No. The power rating does not indicate how loud a speaker is. That’s efficiency or sensitivity, measured in dB / ( 1 Watt x 1 Meter) which tells you how loud your speaker is measured 1 meter away when fed by 1 watt.

Q. Does a high power speaker sound better than low power speakers.
A. No. See first question. It is our personal opinion at fenderguru.com that you should size the speakers “correctly”, matching the amp’s power. The four 10″ speakers in a 40W super reverb will only handle 5-8 watts each during normal playing. There is no point in having 50 or 100 watt speakers in that amp unless you really like the tone in those speakers (other reasons than the power handling). We think it is better to have low power speakers, 20-30 watts, in the Super Reverb so that the speakers are operating in their sweet spot. Some player’s do not prefer the bass notes farting out in the speakers, but others do. How much you push the speakers depends a lot on the tone, attack and playing style. If you play in a smooth finger style you will more likely not need as much firmness in the low end as someone with a firm right hand pick attack.

Q. How do you build a high power speaker?
A. First it is all about the electrical current and the magnetic field that is created. A thick coil wire can handle lots of current from the amp. The larger coil diameter and the more coil windings, the stronger magnetic field will be created. A small gap (in mm) between the magnet and coil wire ensures a high conversion factor between electrical current and magnetic field. Secondly, when you have produced a strong magnetic field you need a strong magnet that can generate a mechanical force/push against the induced magnetic field from the coil. Then you have converted the magnetic field energy to a physical energy (mass and speed of coil+cone+spider). Hence, the coil will start moving and vibrate according to the frequency of the alternating current. An A note at 440Hz will make your speaker coil go in and out 440 times pr second. If the coil is pushed by a strong magnetic field you will need a strong mechanical construction of the spider, speaker cone and coil that is glued together. The spider and speaker cone needs to be firm, tight and thick and must be able to vibrate freely without overriding the physical boundaries at either end of the magnet gap. A large speaker with large pysical dimensions in all ways (coil diameter, vibration range, cone diameter) is able to to push more air. Hence more desibels can be measured over a wide frequency area.

Q. What are the generic tonal differences between 10, 12 and 15″ speakers?
A. As a theoretical exercise let’s compare three single speaker configurations, 1×10″, 1×12″ and 1×15″, mounted in equally sized speakers cabinets. The size of the speaker cabinet plays a significant role and we need to eliminate that factor. And we should compare three speakers that are built on the same design principles, for example Jensen P10q, P12n and P15n. There is no point in throwing in the EVM12L or Eminence Swamp Thang in the comparison against vintage style speakers. First, the bigger speaker diameter the more spread you get, one of the key advantages with larger speakers. The drawback is of course weight, size and the fact that you need more power to run/vibrate the speaker, pushing it into its sweet spot. The bigger speakers can handle more power and more bass since bass frequencies require lots of power handling. However, the 12″ is the overall loudest speaker. It is true that a 15″ speaker can handle more bass and power, but the loudness of a guitar tone lies in the middle and treble frequencies. This is where the 12″ speaker excels with an overall balanced tone. If you have a large 1×12″ cabinet you can actually get more bass from that than from a smaller sized 1×15″ cabinet. On the smaller side, the 1×10″ speakers are faster and quicker in the response. Less current is needed for the speakers to vibrate. You will get improved dynamics and touch sensitivity, which is nice if your music benefits from that. Summarized, there is no speaker size that is superior to the others. But if it was one speaker, one man, one island, we’d go with the 1×12″.

Q. What should one think of when mixing different speakers?
A. Books can be written about this. It’s all about taste and how complicated you want to do things. See the speaker section on our web site http://fenderguru.com. The most important thing is to not mix speakers that are too different in efficiency, brightness and firmness in bottom end. Otherwise you will have a hard time finding a sweet spot on your amp where the volume and EQ settings match all speakers. It also gets more difficult to mic the amp.

Q. Different magnet materials? Ceramic, Alnico, NeoDymium? Should I care?
A. It depends. If weight is an issue and you play powerful amps and speakers, you should consider NeoDymium. Personally we think Alnico is a bit overrated among vintage amp enthusiasts. Some of the best Fender tones we’ve come over is from ceramic speakers, for example blackface Pro Reverb with Jensen C12n. blackface Vibroverb with Jensen C15n, blackface Super Reverb with CTS Ceramic, blackface Princeton Reverb with Jensen C10n. Yes, our Super Reverbs with alnico Jensen P10r are also fantastic, but not necessarily because of the speakers. The frequency response, clarity and brightness of a speaker is determined by many other factors than the magnet, for example the cone material, stiffness, doping etc.