[CQ-Contest] How to rigorously test transmitter audio equalizer settings

donovanf at erols.com donovanf at erols.com
Mon Oct 19 12:39:16 EDT 2020

Hi Alan, 

Have you applied for DXCC Challenge yet? 
More than one hundred PVRC members have. 
Sixty members have more than 2000 and six members have more than 3000 
30 PVRC members have 6 meter DXCC. 
Who says PVRC isn't a DX or a VHF club? 

Your equalization practices are the same as mine. All of my microphones 
are either ModMics or Heil HC-5s. The frequency response seems to be 
essentially identical for both microphones. I don't use HC-4s any more, 
but they were great for old generation radios without equalizers. 

I don't change equalizer settings between operators, although that 
might marginally improve our audio quality. Its just too complex 
with dozens of operators. 

We used a "blind" audio testing process to initially set my 
K3 and FTdx5000 equalizers for HC-5s and ModMics. 

What's blind audio testing? 

The tester uses a transmitter (K3 or FTdx5000) into a dummy load. 
It could also be done by transmitting into an antenna with the listener 
at a different QTH on a dead band so you don't disturb anyone. 

The tester has long list of audio equalization settings to test. Each setting 
is tested at least three times, randomly scattered throughout the sequence 
of equalizer settings to be tested. 

The tester says "CQ Contest CQ Contest Whiskey Tree Lima Papa Lima Alpha" 
for the first equalizer settings 

Then "CQ Contest CQ Contest Whiskey Tree Lima Papa Lima Bravo" 
for the equalizer settings to be compared to Alpha 

He repeats this three times before going on to the next equalizer settings in the list. 

(in contests we never say three, we always say tree ) 

A skilled SSB operator listens on a separate receiver connected to an antenna 
with normal background antenna noise. His only response to the tester 
is Alpha (is better), Bravo" (is better) or X-ray (no discernable difference). 
The listener is not allowed to know what equalizer settings correspond 
to A and B. The tester writes down each A, B or X response from the listener 

The listener hears about a S5 signal, only about one or two S-units above 
the antenna noise. 

The tester runs through a long list of alternative equalizer settings, 
never telling the listener what the settings are. Each equalizer setting 
is repeated randomly many times until the blind listener provides 
consistent results. 

The listener replies with only: Alpha or Bravo or X-ray 

Voila: after about 15 minutes of A vs. B vs. X blind testing you get 
your final equalizer settings! 


----- Original Message -----

From: alanbh at cablespeed.com 
To: "Frank Donovan" <donovanf at starpower.net> 
Sent: Monday, October 19, 2020 3:24:58 PM 
Subject: HC4 mic 

HI Frank, the HC4 has always been touted as a contest mic. I don't know if your read my article some time ago on "eq" settings in the reflector. I have an HC4 and an HC5 plus the Heil Pro set. I consistently get better reports of "good sounding audio" or "your signal has great punch" or "you are really loud but no distortion" on the HC5 mic. The HC5's curve according to the people I talked to at Heil is more like the old D104 with a relative flat response and a believe a 3 dB peak around 2000 Hz. The low end starts rolling off about 300 Hz. I am doing this from memory! 

The HC4's low end starts to roll off around 600 HZ with 6Db peak at 2000 Hz. I may have the peaks incorrect. They could be 6 dB for the HC5 and 12 dB for the HC4 but the HC4 has twice the peak it also rolls off the higher end sooner. 
The HC4 gives a more limited frequency range is tailored to the upper voice range. (where the male voice is not natural) 

Being an audio person the power in the voice is in the lower ranges not the upper. Voice Clarity is centered around 2000. (1500-2300) Voice silbilance is center around 3500 to 4000 which our mics and EQ's won't even allow us to add in. teh power in the voice is down the 300 to 800 Hz range. Intelligibility is not in that range but it raises you over all average voice level. What does this do for us? 

The HC5 gives a specific amount of intelligibility and a specific amount of punch for specific mic and compression settings. In order to obtain the same intelligibility and punch using my HC4 I have to use higher mic gain and higher compression plus reduce the dB in the 2000 range or I get distortion at the higher mic and comp settings. The HC4 is a narrower, limited, higher frequency, more annoying sound on the other end than an HC5. Some people think this is good. This one I just don't agree with my reasons are described below. 

I do not adjust the mic to an individual operators voice. I have found that adjusting the K3's equalizers to the mic element's characteristics to obtain the best clarity and best bunch punch with the least distortion yields the best contest results so that no mater who speaks into that mic his or her voice is exactly reproduced. What does that do? Suppose you have a deep voice. Then that deep voice will be reproduced and that voice will stand out in the crowd and the DX will come back to you. Suppose you have a squeakily little voice. Again you will be a different but clear voice that stands out and the DX will hear it. The key is clarity and punch not the opposite taken to the extreme which is what some of the Italian stations that sound like they are on Helium and holding their noses shut! 

So there is my short epistle on good sounding audio and why I believe it works better pinched down, over compressed high pitched, all sounding the same voices! 

On a another note could you please send me the email address for the BGE person to contact to help me reduce the noise on my neutral line. Tnx again. 


alan WA3EKL 

P.S. I finally confirmed 100 countries on 17 meters with my little point down triangle and 80 watts out of my K3 on FT8. It took me about a year. Already have 110 on 30 meters also with a point down triangle. 
Now if I can just get 9 more on 160 I will have 8 band DXCC. 

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