the Mojave perspective on speakers for guitar amplifiers

Looking for new speakers for your guitar amplifier? Combo or closed back? High power or Low power? We beyond those basics, we’ve got some tis for you that might be of some good help and also clear up some misconceptions as well.

If you’re thinking about speakers, changing them, buying them, wondering what the differences are and what is a good choice, you’ve come to the right place. The first thing to remember is this, Speakers are not right or wrong other then two factors:

1.) Under rated power for the amplifier they will be used with. If the speaker is rated for 15 watts maximum, you do not want to pair it with a 50 watt guitar or power amp. The speaker should be factory rated to equal or exceed the power level for which the driver is to be paired with. Rule of thumb, it’s ok to go over, not ok to go under.

2.) The speaker impedance should be matched to either the other speakers in the cabinet, or exactly to the output of the speaker connection of the amplifier for which it is connected to.

Ok now that we’ve got that out of the way lets take a look at a few interesting misconceptions.

Misconception #1: a Speaker with X impedance sounds better then Y impedance.

Speaker impedance is function of the power transfer equation which is factor of current flow from the amplifiers power stage. In tube amplifiers, the output transformer is engineered so it will reflect the correct needed impedance required for the power tube plates so they can operate safely and within specification while delivering the maximum power output. Therefore if your amp has both a 16 ohm and an 8 ohm output connection, the output transformer will have a tap on the secondary that allows for connection of the 8 ohm speaker and 16 ohm speaker. The tap for the 8 ohm speaker will use less wire to transfer the power while the tap for the 16 ohm will use more. The end result is the power for the given tap is identical if both are matched with the right speaker. The sound should also not change given these perimeters. It is not completely undebatable of course but this is something that is not of concern when looking for speakers.So to put it simply, the sound of an 8 ohm speaker is and should be identical to the sound of a 16 ohm speaker when connected correctly to the power amplifiers output taps.

Misconception #2: ie: A 100 speaker won’t work properly with a 50 watt amp. As referenced in the above statement about power rating, the power level does not prevent an amp from being used with the speaker power rating of a higher value, it does however create a different  scenario if under rated. Therefore, speakers with higher power ratings are safe and probably a good choice to use if your going to use the rule of thumb, need 100, get a 200. That means your not exceeding the specifications more then 50 percent. That will always be a good formula for preventing failure.

Since most speakers are run in a group, you can have a speaker rated smaller then the amplifier because as a group, they collectively add up to more then the individual speaker. This is the typical case for a 4×12 where 4 speakers would be wired in series parallel and the sum total power is 4 times that of the rated speaker power of any single speaker. In the case of a 30 watt speaker, that would mean you could expect at least 120 watts of useable rated power handling.

Hiwatt  made cabinets with 50 watt speakers and they were good for 200 watts and were sold with *DR504s (*Sometimes) and DR103s. They were also sold With DR201s which were 200 watt rated. So the amplifiers varied but the cabinet was good for a maximum to allow the larger of the three to be used. This was a smart way to do things to keep form having to use different speakers.

Misconception #3: the speakers need to be the same type, same brand and same power rating when used together.  Speakers work together and since they an offer different sounds you gain the collective benefit of them as a whole. This is common when using a Celestion™ G12 Alnico blue rated at 15 watts, mated with a Celestion™ G1230H rated at 30 watts. The total power rating can never exceed twice that of the lowest power rating of the two speakers. So, a speaker with a 15 watt rating would only make a cabinet 30 watts capable even though the second speaker is good for 30 watts by itself. In speaker configurations, power is divided equally so if 45 watts were used to power the cabinet with a G12 alnico Blue and a G1230H, you would exceed the total power capacity of the alnico blue by 2.5 watts. the speakers are both receiving  22.5 watts of power. Luckily G12 alnicos are under rated on purpose as are many speakers of good quality. The true power rating is  closer to 20 watts capable. Mixing speakers is a good way to benefit form the qualities and attributes of the different speakers so long as these are done in such as way as not to over lap excessively and create a build up in one particular spectrum of the sound. 2 speaker configurations are common as are “X” pattern 4×12 speaker configurations. An “X” pattern is where you use two different speakers and place them 1/2 on top and 2/1 on bottom thus forming an X from the diagonal corner to corner.

Here is a graph of what frequency spectrum different musical instruments have and their typical corresponding harmonics. Using this graph you can see the range of the instrument, in our case an electric guitar would typically have.

Electric guitar would not need to see  anything under 75 Hz or above 5,000Hz. That means when selecting guitar speakers, it matters that the speakers are within these perimeter. If the speaker is exceedingly high in frequency response, your most likely going to hear unwanted high frequency sounds not to mention that sound disperses differently as the frequency changes. Lower frequency disperse very widely, as you move upward in the spectrum, that sound dispersion is very narrow on a woofer and it is like a beam coming right at you. That is why it seems exasperated or excessive in high frequencies especially when distorted tones are used. As shown above, the higher frequencies are mostly upper-end harmonics. Harmonics carry varying degrees of frequencies depending on the amplifier and type of design. Some amplifiers are great for clean tones and produce many even ordered harmonics. If that same amplifier is driven into a distortion, those even ordered harmonics carry a larger degree of high frequency and that will cause brash and harsh sounding overdrive. Couple this with a bright response speaker and you have a formula for an ice pick in the ear effect. You’ll clear the room fast and also do a good job getting the mice and pests to leave the building. Maybe go into pest control. Sort of the opposite of the pied piper.

Ok, so now what about amplifiers with odd ordered harmonics? they tend to load up heavier on the lower end of the spectrum and the higher frequencies are still there but dissipate faster in energy and therefor aren’t as aggressive sounding as even ordered harmonics when distorted. Maybe I should rephrase that, the frequencies that are produced are very pleasing to our ears and the odd order harmonic typically will behave more favorably for electric guitar overload sounds. The speaker can derail this very easily because if that speaker puts back a strong emphasis on the  high frequency response then your dealing with a counter productive combination.

Now we’re getting somewhere. This is why speaker selection matters so much.

Let me use an example here if I may. Enter the WGS Reaper 55Hz. Most guitar speakers are designed to fit the spectrum of response that you see in the chart. That spectrum will reach pretty far down but fall off pretty hard around 200Hz and give higher frequencies a strong push. This is a carry over from the older vintage designs which most people found pleasant so long as things were kept clean. Usher in the distortions that create strong harmonics and that means your going to get into the ice pick zone very fast if not careful. The WGS Reaper 30 55Hz is different. They took the most desired speaker range and shifted it down a notch. The result is an exceptional extended lower frequency response that holds together very well on the low end and produces good even energy response for under 100 Hz, thus the 55Hz rating. A speakers rating such as 75Hz or 55Hz means its resonant frequency response is maximized at that frequency. That means if you run an equally power signal from top to bottom, the speaker will create a bump in the rated area and increase in volume. But 55Hz is not a common frequency for guitar, the truth is, the strength lies in a second set of parameters. The low frequency has good bandwidth and holds together at the low end giving the speaker great even low end. That is commonly described as a “Tight Low End”. Secondly, This “Shift” I’ve mentioned also means that the movement down towards the lower end has pulled back on the response of the top end. Now don’t fear, this does not mean your going to get a dull response by any means, but it does do something unique, it creates a very good energy distribution on the higher frequency harmonics and prevents them from going into the dreaded “Ice Pick” territory. NOW YOUR TALKIN. That is the hard part in speaker choices for amps that are pressing upwards in the higher frequency harmonics which just so happened to be the vast majority of guitar amps built today. With so much emphasis on high frequency in the over all architecture of many guitar amps, especially those based on JCM800 EQ and or any of the so called Lead circuits, your looking at strong high frequency harmonic energy. The cool part of that is it really gets the sound aggressive and responsive inside the amplifier. The trick is to not allow it to make a full showing at the speaker. Because of the harmonic structures of the guitar amplifiers tone circuits and gain stages, there are many other terrific sounds we like, but that high frequency can be brutal on the listener and that means you. Remember the dispersion pattern is narrowed on higher frequencies. That is part of the problem. So by shifting the speakers response downward, we get an authoritative low end response while smoothing out that top end so it is pleasant and balanced.

This is the power of good speaker selection when choosing your speaker.

One last point. A good speaker will have the makeup of sonic properties which best suit your amplifiers intended purposes. If your amp has terrific high frequency response, your not lacking or for want in that area and a speaker like the WGS is a good choice since they have really come a long way in tailoring speakers for guitar amplifiers with the principle of harmonics and  balance.

There are also a great number of their good speaker manufactures as well. To many to list here but I will say this, of all those who build guitar speakers, most are in the general range of full spectrum and will give different results yet stay pretty strong in the higher frequency arena. That is an important factor in deciding what you need. High frequency is many times the crutch that many amp builders use to get their amps sounding sexy and sharp.

It was once told to me by a friend, Billy F. Gibbons. Eating a bowl of sugar is fine after the first bite, but try getting to the bottom of the bowl.

Translation, to much of a good thing, … well you get the point.

Until next time.