I want to get into this subject because it is important to good audio practice. This article is actually a second part to another article called “Microphone Frequency Response” which should be read first to fully understand the audio that radios and microphones are capable of. Reading that article first may clarify some of the statements made here in this article.
A lot of hams spend big money on these devices, and I do mean big money. These devices are not reasonably priced. But ask yourself this question. Are they really helping your audio, do they just fill a hidden fantasy of having that big comercial radio announcers deep bassy voice? Or are they just there to try and impress others? Let’s go back to the days when we got sick of crappy CB audio and strived for something much better. Back when it was a matter of pride to have good clean natural sounding audio from our nice expensive ham radios. But most of all, let’s use some basic common sense.
MFJ makes an audio device they call an audio conditioner, but it’s just another EQ. And the most popular one on the market is the W2IHY 8 Band EQ and EQ Plus units. (All shown above.)
I had a W2IHY 8-Band EQ and it worked great on my old Icom 706MKIIG. But that radio had a low gain audio amp that was great with an electret condensor mic element. But the audio levels were far too low for any dynamic element like most studio mics have. And the 706 did not have any mic tone settings. So I got the W2IHY 8 Band EQ and ran my former Heil PR 30 through it into the 706MKIIG. I got lots of big compliments on my clean strong audio on HF SSB.
Then I bought my new Icom 746PRO and instantly moved the W2IHY EQ to that radio. I still got compliments, but my local friends said it was not as crisp and clean as it was from the 706MKIIG. I thought that was interesting. So I tried a few EQ adjustments. It got better, but they said it still lacked something. It just wasn’t as clean and natural as it was on the old 706MKIIG.
One day I decided to bypass the W2IHY EQ device, and connect the old Heil PR 30 directly to my 746PRO. The 746PRO has a much higher gain audio amp than my older 706MKIIG has, as does most newer radios today. So I figured it would have enough volume to make the PR 30 provide enough audio. I did a quick wiring just to see what would happen. The PR 30 had a very noticeable hum and sounded very tinny on my 746PRO. Then I remembered that Icom inserts 7.5VDC on the audio line to power their Electret Condenser mic elements, and the coil in the PR 30 was vibrating with the voltage. So I opened the Heil PR 30, and installed a 1uf capacitor in the audio hot wire from the Dynamic element. The hum was eliminated, the tinny sound was gone, and the audio was strong and fantastic. And after a few adjustments of the bass and treble controls built into the radio, everyone told me I got my sweet natural strong audio back and it even sounded a little better than before on the 706MKIIG.
I mentioned this little story because there is an old axium that says, using an external EQ or audio amp, is not always the better thing to do. If your radio can sound great with just the wideband mic, then run it that way. I have always believed that adding anything to an audio line takes away some quality by altering it, instead of allowing the original audio of the mic to pass into the radio. This includes EQ’s, audio preamps, audio conditioners, and even big professional studio mixer boards change the quality of the original microphone characteristics. Something will always be lost.
Audio Compression in many radios also lowers the quality of original mic audio too, so I never use compression except in extreme cases. If the mic has enough audio gain to power up on SSB, then why fix what isn’t broken?
To EQ – Or Not To EQ
That Is The Question.
I have seen demos and brochures about some of the EQ’s and audio conditioners on the market. They have fancy features with switches, pretty lights, and a bunch of slide controls. But are they actually giving you the audio that you think you are getting? In many cases, probably not, and you don’t even know about it.
Mostly because we never get to hear exactly how we sound under good and especially bad conditions over the air. You can monitor yourself with headphones using the monitor jack on the radio if you have that feature. But the sound you hear is not even close to actual over the air sound. And your own voice coming into your ears never sounds the way other people hear you.
You can say you had a friend record you and play it back to you. But you are hearing your audio as received by the audio amp built into someone elses radio, which may have different characteristics than yours or other receiver amps. And it was recorded with a recorder or computer sound card that are never really designed to any set standard of audio. And they are certainly not designed with the same audio standards of a ham radio.
NOTE: Before I go into this any deeper, let me make something very clear. I am not trying to put down any of the W2IHY or MFJ products. I am only using them as an example because they are the most well known and most hams are familiar with what they do. They are good quality products that serve a purpose and have a place with certain ham radios. But this commentary is in reference to any kinds of EQ or audio conditioner from any brand name. They all basically do the same exact thing.
Take The Time To Think This Through
I watched a video online about running the W2IHY 8-Band EQ into the W2IHY EQ Plus device. Now let’s think about this for a moment. Both of these devices have volume, tone, and Noise Gate controls. Each one of these devices can add far more than enough volume, bass, treble, and the Noise Gate to the point of over driving and distortion, all on their own. So why would you want to run one of them into another one, when one of them can do the job with plenty of room to spare? That part made no sense to me. Isn’t that like running a 100 watt radio into a 100 watt linear?
He had both EQ devices in series with each other and connected to his computer to let us hear how the different features effected his audio. Actually, I thought his audio sounded fantastic. Very clean and natural. Then he switched the EQ inline, and his voice gained a Barry White deepness that did not sound natural and kinda muddy. Then he added the second EQ Plus in line and his audio got deeper, even though he had not increased the bass control on that unit. Hmmm. I thought he sounded better before he switched any of the units inline. But once again, we were not hearing this demo over the air from a radio with limited response. We were hearing a Heil Goldline mic through the 2 EQ units directly into a computers Hi-Fi sound card. A big difference and not even close to an accurate demonstration.
This is called “O V E R K I L L”. Your ham radio is not a big commercial broadcasting station playing Hi-Fi digital music. It’s a ham radio with built in audio limitations. Trying to force audio beyond those limits actually takes something away.
ECHO??? Are You Kidding Me????
One thing that surprised me greatly was the W2IHY EQ Plus device. It actually has a feature that will add echo to your audio. The one thing that many stupid CB’ers have proven to us for years, is that adding echo does not improve the quality or the readabillity of the operators voice. In fact, echo tends to lower the intelligabillity of the operators voice, making it harder to understand. So why would a ham operator who knows better, include an echo feature on an audio device designed for ham radios? That one completely escapes me.
There is another drawback to using one of these devices. Your radio is limited in audio frequency response. You can not increase what the radio is not capable of producing on it’s own. When you try to do this, the result is always distortion, or loss of the true original frequency response of the radio and the mic. That is something CB’ers prove when they crank their power mics up to 150% modulation. And you see just how well that works for them.
Also, your radio is designed to accept and work correctly with 600 ohm microphones. The EQ device outputs far higher than 600 ohms from the output of it’s built in amp circuit. This is an impedance mismatch and changes all the characteristics of the audio. Any time you add a device in the audio line, you change the characteristics of the original audio quality. Basically, you lose something. The reason is impedance mismatch. You can not feed a 5,000 to 10,000 ohm output into a 600 ohm mic input, and expect no changes in the frequency response and sensetivity in the audio.
The Nitty Gritty Facts
If the mic you are using does not produce good enough audio fidelity all by it self, then…
1. you are most likely using the wrong microphone,
2. you do not have the audio controls in the radio set correctly,
3. the radio is just not capable of what you expect from it,
4. All of the above or any combination thereof.
Some less elite radios that do not have higher gain audio amplifiers or any kind of built in tone controls for the mic audio, may benefit slightly by adding an EQ or an audio conditioner inline with the mic, but not both. My older Icom 706MKIIG is that kind of radio, as I described earlier. And there are several smaller, less featured radios on the market that are the same way. They do not have any kind of mic EQ or tone controls to tailor the audio of a good quality mic. The result is good clean audio, but kind of flat. No natural bass or highs even from a studio mic. The EQ helped my 706MKIIG to gain a better tone quality that the radio lacked alone.
But if you have a more elite type of radio like an Icom PRO series or higher, or the Kenwood TS-2000 or TS 590, or any equivilent radio that comes with a built-in mic EQ or tone settings, there is no need to spend $600 on EQ’s and conditioners. Adding an EQ or conditioner or both will actually degrade your original full range audio on this type of radio. These are not designed to use external EQ’s or conditioners. That is why they include built-in tone control features.
So What Have You Learned Here?
1. DO NOT use external inline EQ’s or amps if it is not necessary. And in most cases, it really is not necessary. They just rob audio quality. Let the radio handle the original quality of your microphone’s audio. It will sound a lot better and far more natural. Besides, many radios like my 746PRO have a built-in tone control for the mic to raise or lower the bass and treble in each mode separately. Why add an EQ when you already have one in the radio?
2. EQ/Audio amps are designed specifically for radios that have low gain mic amps that do not work well with Dynamic mic elements. But if your radio has a higher gain audio amp built in, then using an external device in the mic line will actually decrease the quality of the mic. Always try the mic directly into the radio first to see what it sounds like. If it sounds good, an external device will not make it sound better.
An EQ serves just one purpose. To increase or attenuate the dB levels of different frequency ranges of a mic element. This can be good for home stereo systems that have the full human hearing range. But for our communications radios with limited frequency response, this can not be done with any kind of efficiency. A mic element has built in limits by design, and you can not increase a frequency that the mic is incapable of producing. The result is usually some level of distortion, or it gives the audio an artificially and overly compressed type of sound.
3. If your audio quality is not an important issue to you, then forget everything you just read. You will consider it a waste of time. But if you take pride in how good your expensive radio sounds to others like I do, then do every thing you can to get that fantastic audio.
Do not waste your money on unnecessary external devices like EQ’s and audio amps just because it looks really really cool sitting next to the radio, and you think your friends will be impressed when they see it. Impressing people with expensive devices is worthless if your audio lacks quality because of it. We are hams, not CB’ers.
Article by K3DAV originally available at http://www.k3dav.com/externalaudioequalizer.htm