SDS100/SDS200: Question about SDS200 external speaker jack configuration

[sammywala]

I have a question about the external speaker jack on the Uniden SDS200. I am trying to find out what the configuration is. From the several radios I use, the external speaker jack is monaural using the tip and sleeve (T/S) configuration. The tip is the audio signal and the sleeve is at the radio’s chassis ground potential. I am hearing the SDS200 and other scanners with external speaker jacks may not have the same configuration. I was told by a vendor for Uniden that the SDS200 external speaker jack is stereo, even though the output audio is monaural. That would indicate that the tip-ring-sleeve (T/R/S) configuration is being used. He did not know if the audio signal was on the tip or ring or if the sleeve is at chassis ground potential. I contacted Uniden and they were not able to answer my question. I have a speaker distribution switch box that requires the external speakers to have a monaural output with the sleeve to be at chassis ground potential. If anyone knows how the external speaker jack on the SDS200 is wired it would be very helpful. Thank you

 

[doctordialtone]

SDS100/SDS200: - Headphone Jack

Looked in the manual can't find the answer. Headphone jack, Mono or stereo? Thanks

forums.radioreference.com

 

[wtp]

from the uniden manual
You can use an optional 32Ω stereo headset or earphone with your scanner. Use of an incorrect earphone or headset might be potentially hazardous to your hearing. The output of the phone jack is monaural, but you will hear it in both headphones of a stereo headset

https://www.uniden.info/download/ompdf/SDS200om.pdf

 

[fxdscon]

I have a question about the external speaker jack on the Uniden SDS200. I am trying to find out what the configuration is.

If you are asking about the speaker jack on the REAR of the SDS200 labeled "EXT. SP." , that is a mono output.

I was told by a vendor for Uniden that the SDS200 external speaker jack is stereo, even though the output audio is monaural.

That sounds like he was describing the headphone jack.

Headphone jacks are stereo on all our scanners. EXT SP jacks are mono.

 

[RFI-EMI-GUY]

The external speaker jacks on these radios are monaural bridge tied load (BTL) amplifier configuration. * They want to see a balanced load like a speaker or transformer that is floating above ground and below 13V. In no case should the leads be grounded or pulled up to battery voltage. The amplifier can be damaged, or at best distortion occurring. Don't connect directly to an unbalanced sound card without going through a balance transformer. Yet everyone does which is why the feeds all sound crappy.

* simplistically on a block diagram it appears to be a stereo amplifier but schematically and functionally it is not, thus the confusion.

 

[RandyKuff]

It is a stereo type plug and according to one of Unidens Speaker manuals they terminate it to the Left side only...

 

[n1chu]

I do not believe the jack is at chassis ground. Didn’t Uniden change that due to a concern about damaged hearing when using earbuds and forgetting to turn the volume down first? I recall using a short jumper on a handheld scanner. It wrapped around the outside barrel of the BNC antenna connector (chassis ground) and the headphone jack, which had its own different level of ground for the hearing concerns mentioned above. The volume level jumped up appreciably, because the headphone jack’s ground was not chassis ground until I shorted it out. (My main use for the earphone jack was for using a better sounding external speaker. I didn’t need or want Uniden dummying down the max volume level but understand why they did.

 

[sammywala]

Thanks for all the input you guys gave, it is appreciated. Confirmed what I thought that they are using a bridged mono amplifier and it does not use chassis ground. I had an audio amplifier I tried to use to amplify the earphone jack output of a radio, the amp is stereo but can be configured to mono. When I connected it to my speaker system in the mono configuration it did not work, it produced howling and distortion. It would probably work if I only connected one external speaker to it but my multiple external speakers through the speaker switch box are all shield at chassis ground (only one speaker can be selected at a time). I thought maybe an audio isolation transformer might work, with the external speaker jack connected to the primary and one connection of the secondary could be connected to chassis ground and the other end of the secondary would be the audio output to the speaker switch box. However, I was unable to find an audio isolation transformer with a 1:1 turns ratio with 8 ohms impedance on both the primary and secondary of the transformer. Thanks for all your input.

 

[RFI-EMI-GUY]

It is a stereo type plug and according to one of Unidens Speaker manuals they terminate it to the Left side only...

View attachment 156817

"It is a stereo type plug and according to one of Unidens Speaker manuals they terminate it to the Left side only..."

I would bet you pulled that from a very old speaker spec sheet. not for SDS 200 speaker or BCD536 HP.

 

[RFI-EMI-GUY]

Thanks for all the input you guys gave, it is appreciated. Confirmed what I thought that they are using a bridged mono amplifier and it does not use chassis ground. I had an audio amplifier I tried to use to amplify the earphone jack output of a radio, the amp is stereo but can be configured to mono. When I connected it to my speaker system in the mono configuration it did not work, it produced howling and distortion. It would probably work if I only connected one external speaker to it but my multiple external speakers through the speaker switch box are all shield at chassis ground (only one speaker can be selected at a time). I thought maybe an audio isolation transformer might work, with the external speaker jack connected to the primary and one connection of the secondary could be connected to chassis ground and the other end of the secondary would be the audio output to the speaker switch box. However, I was unable to find an audio isolation transformer with a 1:1 turns ratio with 8 ohms impedance on both the primary and secondary of the transformer. Thanks for all your input.

Radio shack and some auto sound manufacturers used to sell a decent audio isolation transformer (hum buck) that was effective in providing a balanced match for driving a high impedance amp or sound card. They are stereo so useful for two radios. The drawback is that RCA phono plugs are fitted, so you have to adapt to what the radio has.

 

[RandyKuff]

"It is a stereo type plug and according to one of Unidens Speaker manuals they terminate it to the Left side only..."

I would bet you pulled that from a very old speaker spec sheet. not for SDS 200 speaker or BCD536 HP.

That's correct... Just posted that to show that the Uniden speakers are only tying to the Left channel pin on the plug... I know, I have one and thats how it is terminated... Works fine on my 200... With plenty of volume...
Wasn't referencing how the jack on the 200 is setup...

 

[Ensnared]

I don't understand why the eternal speaker is wired for stereo. Stereo has a left/right channel. Why would a mono need to go through a stereo setup. I can achieve stereo (two channels) by having two mono earphones, one in each ear. That is, two scanners or a CB and scanner. I think it is stupid to waste two ears on one radio. I know this is weird, but this has saved my marriage & made me a happier man.

 

[RFI-EMI-GUY]

Well because; It is not stereo.

Bridged and paralleled amplifiers - Wikipedia

en.wikipedia.org

 

[Ensnared]

View attachment 156861

Well because; It is not stereo.

Bridged and paralleled amplifiers - Wikipedia

en.wikipedia.org

Thank you for the schematic. Since I am unfamiliar with basic schematics, I would like to ask some questions:

1) How does this differ from a mono setup? 2) When it gets to the ear, how do the audio dynamics differ from a mono setup?

I have never heard a digital scanner that compared to the audio quality of the GRE PSR 500. I believe it was mono. The Uniden 536HP & SDS 100 appears to have similar-sounding audio.

I am going to play safe. For the SDS 100, I rip the earphone off of the right side so I hear it in the left ear. I use a mono over-the-ear mono earphone for the CB on right side. Although it is impossible for the brain to synthesize two audio sources at the same time, I manage quite well.

Thanks for the information.

 

[RFI-EMI-GUY]

Thank you for the schematic. Since I am unfamiliar with basic schematics, I would like to ask some questions:

1) How does this differ from a mono setup? 2) When it gets to the ear, how do the audio dynamics differ from a mono setup?

I have never heard a digital scanner that compared to the audio quality of the GRE PSR 500. I believe it was mono. The Uniden 536HP & SDS 100 appears to have similar-sounding audio.

I am going to play safe. For the SDS 100, I rip the earphone off of the right side so I hear it in the left ear. I use a mono over-the-ear mono earphone for the CB on right side. Although it is impossible for the brain to synthesize two audio sources at the same time, I manage quite well.

Thanks for the information.

The schematic is for the SDS200 speaker jack on the rear driving tip and ring.

1) That is a mono amplifier. It has two amplifier sections A1 and A2 that work 180 degrees out of phase with each other to deliver maximum power. 2) Its mono.

As far as the SD100 I assume the earphone jack is also fed from a BTL amp as it is a common part these days but I could be wrong. The manual is not informative.

 

[Ubbe]

As far as the SD100 I assume the earphone jack is also fed from a BTL amp as it is a common part these days but I could be wrong.

If I connect a stereo plug it measures 0 ohm from the sleeve to ground and the left and right channels are tied together to get a mono sound in the same phase to earphones, so no BTL. It doesn't really need high power to earphones but it is usually easier to take the audio from the speakers BTL circuit and reduce the signal by a couple of resistors, instead of doing a separate amplifier solution. So probably no BTL to a SDS100 speaker, as that tiny speaker can't handle any high power audio anyhow. It's an 8 ohm 1W speaker so will give full power at 3volt rms.

/Ubbe

 

[kruser]

I have a question about the external speaker jack on the Uniden SDS200. I am trying to find out what the configuration is. From the several radios I use, the external speaker jack is monaural using the tip and sleeve (T/S) configuration. The tip is the audio signal and the sleeve is at the radio’s chassis ground potential. I am hearing the SDS200 and other scanners with external speaker jacks may not have the same configuration. I was told by a vendor for Uniden that the SDS200 external speaker jack is stereo, even though the output audio is monaural. That would indicate that the tip-ring-sleeve (T/R/S) configuration is being used. He did not know if the audio signal was on the tip or ring or if the sleeve is at chassis ground potential. I contacted Uniden and they were not able to answer my question. I have a speaker distribution switch box that requires the external speakers to have a monaural output with the sleeve to be at chassis ground potential. If anyone knows how the external speaker jack on the SDS200 is wired it would be very helpful. Thank you

Read this post Bcd536hp external speaker connection considerations and precautions and pay attention to the drawings inside that posts zip file. One of those drawings should work for you. I've used one of them for years now but I already had the small audio transformers I used. Mine were not exact but for simple audio, they worked perfect with my Motorola amplified speakers which all share a common ground with the power supply ground.

Maybe read the entire thread as it has some good info on rolling your own interface.

 

[Ensnared]

The schematic is for the SDS200 speaker jack on the rear driving tip and ring.

1) That is a mono amplifier. It has two amplifier sections A1 and A2 that work 180 degrees out of phase with each other to deliver maximum power. 2) Its mono.

As far as the SD100 I assume the earphone jack is also fed from a BTL amp as it is a common part these days but I could be wrong. The manual is not informative.

Interesting. I got to thinking about this while driving yesterday. I believe the audio quality I referenced is associated with the speaker. When I use BT, the sound is rich, depending on the BT speaker.

I will continue using ear buds because they are almost everywhere along the highway.

I used to buy the mono Diesel brand that used to be sold at truck stops. You can also buy a similar-looking one from Crane Radio, with a "stereo plug."

Over the Earphone (Stereo Plug)