Purpose of 1K tone...

[144inBama]

Just sitting here this morning, having my daily cry before heading into work and was thinking..."why do we use a 1K tone when we don't have a 1K voice?" Sooo.....why do we use it? I mean, I can understand it being used as a baseline, but let's say you tune it perfectly to 1K, looks awesome on the scope, but due to your voice freq, the audio processor doesn't respond well because of "weak" components or your voice just sounds like Harold Reid from the Statler Brothers or Edith Bunker....Is it possible to tune the radio to "your voice" for better audio response or clarity?

 

[sp5it]

If you can make your voice look smooth on the scope to tune TX path, sure you can

 

[Handy Andy]

That question comes up a lot at shops...

How to bring my voice out...(not necessarily in those words, but) how to make my Radio more Loud is the premise...

There are several threads about people using Equalizers, Compressors, Better Mic Elements...even how to inject Hi-Fi thru Wi-Fi into your Hi-Po Miracle.

Most shops shove a Clone of Communicational Contrite in your face and say;

"Buy this! You'll be heard throughout the county ..."

​

Before you can even analyze, let alone answer...

"For - just an extra $70 we will even wire it up for you and throw in a Battery for Free...!!!"

Caveat Emptor!
​

Just don't forget to read the Fine Print...

Sigh - You did ask...
​

But little for just using your CURRENT equipment ..

Doesn't say much...

At least no one wants to go down a (Rabid) Rabbit hole to find those answers...Or is there a way?

Most people say - it's not worth it...

They Encounter...

• Boomy Distorted Audio
• Poor sounding Station
• Angry Neighbors
• Become Laughing Stock of that very same County

IF that is the case, then why do they try adding all this other crap to the bill as external accessories that will need more batteries - wall-warts and tangled up mess of cords?

Only to Encounter even more...​

• Distorted Boomy Audio
• Poor sounding Station
• Angry Neighbors
• Become Epic Facebook Pundit of that very same County

Why do that?

Because most "mods" done to the inside of a radio is to cut the limiter - add a few caps in and never look back no matter what the customer may say about the shop - There's one born every minute - they became very happy Shop owners when that Minute came thru their door...

You ask about a 1K tone, and you already know if you have "The Voice" for 1K tones, you wouldn't be trying to buy a CB Radio - you'd be working at NBC - being the Test Tone...

​

You know, I spent a lot of my "idle lean time" as "Clean Time" at Electronic stores - gave me time to think about ways to do things that may take a little more effort. Design a few ideas penciling in, while winding my day down, doodling on a local Cafes' Placemat and find answers - but when you approach the Boss at the morning coffee meeting about the concerns of the shop - you usually meet, and Greet, an angry Mob...

Hmmm...Speaks Volumes (Pun intended) when it comes to working methods of application to the various other duties a clerk must perform, like Sales for example...

So that's where Forums like this one come into play.

We are a Beacon, a Yellow Porch Light to light the way to better equipment more better audio - more better way to say things and not make up double redundant's even better!

​

But I digress...

You have to know limitations and how filters work so you can do more with what you have to improve filtering...

It takes time and patience, although good to have, not many CB Radio enthusiasts have both to work with.

I am not asking people to spend thousands of dollars on new equipment - just understand some simple changes made inside a radio you currently use, can go long ways in making your radio more Intelligible - that unless you have that kind of money to spend - you would not be here reading this - you'd already have spent it and now are figuring out how to wire it all up...

Oh, Hello - that must be you...

Quiet You numbskulls - I'm broadcasting!
​

Ok, most users clip limiters and throw on the Contrite Clone of a D104 (With the Free Battery) - so most of what I can do to help them, has and already is, taken away from me by doing just that...

If you try and add more to the above two items, you're going to wind up in a much bigger mess - only now - the Big of that Angry Mob of Neighborhood Associational Associates Slippered Spouses has grown bigger and are now appearing with large long poles big sticks and torches...wanting a piece of you

Nothing big - right?​

Again, every time I try to offer a simple Mod, someone comes along and says "I can do better!", further research shows their tricks are from some of the many predecessors of previous mods and the changes between different radios of the same platform - so who wins?

No one really, for the noise just gets too loud to deal with.

So my efforts are drowned out by the shouting...

Subtlety is a lost art, people are angry and they want serious changes and demand results.

So they buy that better equipment - that doesn't solve the problem with the personality of the performer.

As (someone famous) once said...

​

I'd like to think that my input matters, but in cases of simple 1kHz test tones, my efforts are not the best application to that...

What I am offering is more effort towards making, that which you have, work better - in more ways, for you.

But if all you want to be is louder, or more like that 1kHz test tone - Monochromatic, then, what I offer cannot help you.

Many people really don't know what they want, you raise the carborundrum of;

- If you want Loud, Press 1,
- If you want to be Heard, Press 2
- if you want to be Loud to be Heard Press 3 (<Beep>)

"We're sorry the caller you are trying to reach is no longer available...Please Hang Up and Try Your Call Again...<(*Click*)>​

So to answer your question - ponder the following...

Test Tones were for efforts of Producers and Production workers to show Purity in faithful reproduction of an audio signal...

Most Test Tone - were Test Tones - and is plural - more than one is used to generate a set of summed and subtracted notes or tones from the initial set (usually two).

Helped to determine bandwidth and how well it transmitted that effort.

So voice - being what it is, like a sonic fingerprint - each one is different yet produced by the same organ. We're just shaped differently to produce the "overtones" and the Fundamentals that make us what we are...not 1kHz test tones - as you observe, we are unique in that aspect.

That's where I work...and No, what I discuss is not going to make you sound like Ethel Merman or Barry White - just ... you.

If you wish to go down that rabbit hole, that is your choice - alone. For as with anyone else, this too applies...

The work and designs and modifications shown are for
EDUCATIONAL PURPOSES ONLY!
You proceed at your Risk and Peril.
If you are not sure, or Understand the Ramifications
or are unable to do the work required, PROPERLY...
Please STOP!
Refer this effort to a Qualified technician.

​

I'll wait here...

 

[DoctorAudio]

A 1K tone or all of the science and technical jargon in the world, won't matter if you don't keep the string tight..

 

[TM86]

I always thought the 1k tone was done because it was the standard test tone brought over from the phone system. Well within the margins for audio on even the lowest fidelity systems.

 

[Shadetree Mechanic]

The 1k tone is just a reference. It is a way to set up radios in a repeatable fashion. The same type of thing is done when setting up sound systems. Car audio has a system made by Steve Meade Designs that has you setting the gain on your audio amplifiers while monitoring the output for clipping while using the supplied reference tracks depending on the level of the recorded material you will be playing. This is done to establish a safe maximum for your volume control. But then you play a song that was recorded louder and your reference goes out the window. The setup is not the end all be all, it is just a reference. So the sound system user needs to know that when playing full tilt, they are flying by the seat of their pants. The same goes for transmit audio on a radio. The CB factory safely sets the modulation below 100% so they don't get dinged for someone's loud voice. Turn it up to 100% and it is easy to go over, but that doesn't necessarily mean that it will sound bad with a loud voice. There is a little bit of leeway there where it starts to look bad on the scope but still sounds good. Using a monitor radio with no antenna and headphones is a good way to get a feel for what you sound like and is essential for setting the mic level. An even better station monitor is an SDR dongle plugged into the USB of your computer with no antenna. This way you can record your transmit to know for sure what you sound like. The radio with headphones does ok, but the audio mixes with the sound of your voice that travels through your skull so you may not get the true sound of you. I would not operate my station without a monitor, I usually do a quick check when I first power up. Along with an SWR check and power check. Just to make sure everything is ok before I really start talking.

 

[Handy Andy]

No matter what, that 1kHz tone is simple - a TEST tone.

It's really not meant to be used as replacement for the human voice...although some radios in their stock form - you kinda' wonder...

 

[Big Kahuna]

Wow - I just did a search and found this thread because this exact question came up in a discussion with someone yesterday.

Why do we use 1kHZ 50mV? What was the historical reasoning that this became the standard in radio equip and studio testing, etc.?

Additionally, it was brought up that the supplied tone always mentioned in manuals for setting modulation seems much stronger than most voice peaks would hit regularly. So in factory service manuals is it referenced purposely to reduce the likelihood of violating FCC rules?

How do you set yours? Right at 100% with the 1kHz tone like the service manual says...or slightly higher?

 

[sp5it]

I set to 98% negative peaks.

 

[freecell]

the 1 khz. tone is part of a transmitter amc specification that is always stated in connection to a recommended voltage level to be applied to the microphone input to establish a threshold or reference voltage for the following speech amplifier stages. when mic input exceeds this level the gain of the speech stages is reduced and when mic input drops below this level the gain of the speech stages is increased, assuring maximum average power output from the transmitter over a wide range of variables such as distance from the microphone element, the wide range of speech energy in the human voice (which is by nature asymmetrical) and varying levels of energy when speaking in anything other than a normal conversational tone of voice. the voltage level is usually stated @ 30 millivolts in most exports while by comparison, in a 148gtl using high and low level class b modulation the voltage input level is 50 millivolts.

given average long term speech within the allotted spectrum averaged over a time period of 60 seconds, the maximum speech "energy" is in the 250 hz. and the 500 hz. range while over 80% of speech "intelligibility" begins above 500 hz and up. while the lower-frequency range corresponds to the vowel sounds, the higher-frequency range in the 500 hz. to 4 khz. region corresponds to consonant sounds. (typical human male speech spectrum)

 

[Handy Andy]

Additionally, it was brought up that the supplied tone always mentioned in manuals for setting modulation seems much stronger than most voice peaks would hit regularly. So in factory service manuals is it referenced purposely to reduce the likelihood of violating FCC rules?

I didn't get much of a response, so do you want to know what Good-ol Handy Andy Would Do (GHAWD)?

Takes two radios - one just to monitor - on the same channel.

You throw a carrier using the Hand Mike (or Customers Favorite Mic) - you set up a feedback squeal loop using the Monitor Radio as the Source of the sound - with your Mic in the Radio you're tuning up to be the pickup.

• For best results, use a Monitor Radio that is a known good quality receiver, one that can give you the tonal quality response - thru it's own internal speaker or the use of an external speaker.
• The more natural the sound, the better.

You simply make the Feedback squeal LOW - Enough (quiet) to begin the feedback - just as the squeal - you can then tune the AF strip - Say Cobra 29 - mostly the TX Strip L14...

​

Although the most easier and most popular method to use, but is it the right one or if it is right, what is the best way to tune with it?

That is the subjective part, but to be honest, the "squeal" effect is only part of this - the squeal is the easier path of audio feedback so it' is the PREDOMINATE tone the radio peaks out the most in audio bandwidth to use.

Once you know that path, and the predominate tone, it's not 1kHz - it's something else.

You'll find the squeal is the easier path and the easiest way to observe SATURATION - the sheer amplification distortion of that fundamental.

So do you tune for that Squeal?

• - in most cases - you can, and get away with it, but remember too, the level of power ENVELOPE being developed in this area is frequency dependent - so it's going to follow more the fundamental bandwidth than anyone's voice

The trick here is to listen to the entire spectrum getting passed - you set the monitor radios' speaker output so you can hear the "Background" of the room - BEFORE the squeal occurs - this may mean resetting the Mic Gain (Dynamike) and these matters. But overall, the emphasis here is to tweak the mic's own pickup tonal pattern for best results of the drive - not the radios' "tuned" set of bandwidth frequencies - there is a difference.

It may mean you have to reset L17 (the Pre-driver coupling coil) to obtain the spectrum - but that is what the tune up is really about - bringing out the voice of the operator/personality - this is why Galaxy and other AM-Regulation Radios tend to excel at the bandwidth drive - you don't have that kind of bandwidth in the 29's and other Transformer-based radios.

• What I'm trying to emphasize here: Many people have asked why do you have to whistle into the mike (mic) to make the radio even swing forward?
  • To provide a simple answer is, you're overdriving the amplifier that takes your audio and puts it into an RF signal to get it out there.
  • Re-think before you jump on the keyboard and complain.
  • Does your voice mimic the sound of a whistle? No!
  • But to a Radio - it doesn't matter - it still is a sound the radio will try to amplify.
  • Ever notice how the 1kHz tone and the Whistle are pretty close in fundamental tone?
  • That is the point I'm trying to bring up - many others are also hitting it...
  • Reproducible results - doesn't matter how, but if it's consistent - it happens.
  • So they use a Higher pitch tone than most people talk - but the other side of this coil is the intelligibility of such sounds needs to have their higher tones to be discernable.
  • So in a way, your 1kHz test tone, being what it is, is a trade off between a range of vocal sounds of consonants - versus the range of vocal energy used for Vowels.
    • When you talk to someone - face to face, they look at you and watch your expressions as you talk - you don't have this when you use radio.
    • Instead you have you listen to their voice and use methods of perception to detect...

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So when you use your regular voice, unless you have some method in which to generate AVC (Automatic Volume Control) - a from of compression using Volume - you have a rather wide dynamic level of - well, noise! Yes, Noise! that a person has to wade thru to find the meanings.

So in all that noise is tonal effects - inflections - embedded within the persons speech - if the radio is not able to pass thru all the vocal range of sounds the person produces - you don't always understand or discern what they are talking about.

This is why I have so much to say about that 1kHz Test tone, I've had to set up systems to help others' understand a person with a speech impediment.

• - they aren't handicapped, just unable to speak in a manner others can easily understand.
• They had limited vocal abilities due to damaged vocal cords (or folds)
• - so I had to really re-work a radio or two to help the person communicate. Just had to open up the bandwidth of speech thru the radio - some tweaking of the mic amp and Audio Amp and it's path helped him to be able to have his full range of voice be heard - including the inflections.

I could go on, but the above is a primer, the next step is to start tweaking the capacitors in the strip to help elevate the vocal presence

 

[Big Kahuna]

I knew I could count on you guys for some good responses I find these threads much more interesting than "what amp should I buy"

 

[Crawdad]

How dare you. ........

 

[TM86]

I knew I could count on you guys for some good responses I find these threads much more interesting than "what amp should I buy"

The big one.

 

[Alabama Buckeye]

Freecell said, "...when mic input exceeds this level the gain of the speech stages is reduced and when mic input drops below this level the gain of the speech stages is increased, assuring maximum average power output from the transmitter over a wide range of variables..."

My question is: With respect to radio communications, is this "maximum average power" the principle instance to which this oxymoronic terminology is applied?