SDS100/SDS200: Headphone Jack

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Ghost4658

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I put a Mini amplifier made for a motorcycle on the back of a Uniden BC 15 speaker hook the speaker to one side of the stereo amplifier and plug the amplifier into the headphone jack on my sds100 now got all the volume I ever needed
 

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JoeBearcat

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No, the earphone jack on the portables can not be changed to be an external speaker jack.

If more audio is required, an amplified speaker can be added. (which can be modded if required)

Not only would Uniden be liable for excessive levels, but anyone who changes the level of the earphone jack and later sells the unit may be liable for the new user's hearing damage. At that point, Uniden would be able to prove the unit was tampered with (modified), so Uniden would not be the liable party.

Even a warning that "you may risk hearing damage" may not absolve Uniden if damage were to occur.

The amplified speaker is the answer.
 

Ubbe

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There's no logic to it and a bit ridiculous as they haven't restricted your living room HiFi system to 10W as higher powers could damage your hearing. It's impossible to restrict an amplifier to a set safe level as there are earphones and headphones of different types and models that have a huge difference in efficiency and audio pressure to the ear. If it feels uncomfortable to listen at high volumes you should probably lower the volume to avoid hearing damages, in both cases when using earphones or loudspeakers. It's common sense. The legal system in US has gone out of hand.

/Ubbe
 

JoeBearcat

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There are also technical differences in that earphones are 32 ohm devices and speakers are generally 4-8 ohm devices so the jacks are designed for those devices expected to be connected to them. There is also a substantial difference between a device IN your ear vs a speaker that is not as closely 'connected' to the ear drum.

Line outputs, Earphone outputs, and Speaker outputs are three distinct devices and cannot be interchanged as desired.

There is a ton of logic to it - including the desire to not invite lawsuits. Even if you do not agree, you are not the one at risk.

Again, the proper solution is to use an amplified speaker that you can turn up as much as you like.

The irony is that there are complaints about the weather alert features were there are MINIMUM mandated levels and we have many complaints that the alerts are "too loud". But again, it is a matter of complying with laws and avoiding lawsuits. It's easy to argue that it should be difference when you have no dog in the fight (not that I condone dog fighting - it's just a common phrase).
 

Ubbe

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it is a matter of complying with laws and avoiding lawsuits.
I agree, but those laws are crazy and have no logic to them other than some lawyer started to claim that it wasn't the users fault damaging his hearing when turning up the volume too much over an extended long period of time. It should never have been acknowledged by the court system that it was the fault of the product manufacturer.

I run a 2 ohm speaker from the earphone jack on a SDS100E at a volume 6 setting with a sound level high enough as it would be a speaker out jack. Earphones can have a spread of 80-115dB SPL in sensitivity where a 3dB difference are perceived as double or half the volume level to the ear. SPL are the sound pressure emitted when feed with 1mW of power. It makes it impossible to try and regulate the output level by law from an earphone jack to keep a safe level to a human ear, when earphones can vary that much in sensitivity level. The longer time you listen the lower the volume has to be to avoid hearing damages.

Understanding Earphone / Headphone Specifications (shure.com)

/Ubbe
 

AK9R

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...but those laws are crazy and have no logic to them...
Unfortunately, those sorts of "laws" are common in the U.S.A. Note that I put "laws" in quotation marks as there may or may not be product safety laws in place here. But, there may be product safety rules implemented by bureaucrats in response to legislation or there may be court cases that set precedent or there may be corporate legal teams who are trying to protect the corporation from future legal challenges.

There was a celebrated case several years ago involving a woman who went to the drive-through at major fast-food emporium. She ordered coffee which she then spilled in her lap causing burns to her skin. Was it the restaurant's fault that she spilled the coffee? Was it the restaurant's fault that the coffee was served scalding hot? The court, aka a jury, ruled that the restaurant should not serve their coffee that hot. So, the restaurant had to make some changes to their procedures and they are now careful to warn you about hot coffee.

Seems ridiculous, right? Whatever happened to common sense and personal responsibility? How did we become a country where we expect the courts, the government, and major corporations to protect us from our own carelessness or stupidity?

Frankly, I think, i.e. it is my opinion, that this whole headphone jack thing is a waste of time. Uniden's engineers made a decision that possibly was driven by Uniden's lawyers. Unless you can show that Uniden's production department installed the wrong parts or installed them improperly, there's probably nothing that can be done other than external workarounds. It is what it is.
 

JoeBearcat

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I agree, but those laws are crazy and have no logic to them

AK9R said it well. Even if the laws make no sense, they are still laws and corporations
cannot simply ignore them and expect to not have them used against them.

Crazy laws need changed, but until that happens they are still laws.
 

aprswatcher

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Uniden reduces audio output power at the headphone jack to avoid legal liability for customer's possible hearing damage if the volume is set too high. There may also be regulations in places like California that bear on this issue. I would not expect Uniden to change their position on this.

The audio power reduction at the headphone jack has generally been done with a resistor network. If this method is also used in the SDS100 then firmware cannot reverse the power reduction.

The Uniden BC23A amplified speaker can be modified for higher gain and that may bring the SDS100 to full volume. There is a noise filter button on the speaker that rolls off frequencies above 5 kHz. We can use that switch as a gain selector with a small modification. Referring to the attached schematic, find the two resistors, 680K and 560K, in parallel. They are near the bottom of the page connected to switch S1. Connect a 47K resistor across (in parallel with) either resistor to increase the gain by about 16 dB.

Now when the noise filter button is pressed in the speaker is at low gain with 5 kHz roll off. With the switch pushbutton in the out position the gain is increased by 16 dB with no roll off.

I didn't take a picture of the board when I drew up the schematic. If someone posts a high resolution picture of the board, I can point out the location of the resistors.
I purchased the Uniden BC-23A amplified speaker on E-Bay, it was modified so that it would not shut off after 20 seconds of no activity.
I added the 47 K resistor as mentioned by "pro92b" and it works fantastic! It was a little hard finding those resistors but with a good magnifying glass and bright light I was able to find them.
Thanks for posting this modification "pro92b"
73, Rex
 

emscapt9816

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I purchased the Uniden BC-23A amplified speaker on E-Bay, it was modified so that it would not shut off after 20 seconds of no activity.
I added the 47 K resistor as mentioned by "pro92b" and it works fantastic! It was a little hard finding those resistors but with a good magnifying glass and bright light I was able to find them.
Thanks for posting this modification "pro92b"
73, Rex
Picture?
 
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