Many Scanners on one pair of Speakers?

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kruser

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Hi gang,

I'm looking for an easy solution for scanner audio.
I collect scanners and repair/restore older ones.
I've finally built myself some shelf space and what not plus wired in power and several Stridsberg 8 port multicouplers so I can have all the radios working.
My big issue now is audio.
Many of the older scanners like the old bearcat III and 12 and the likes had front facing speakers so that works well but many of the newer models and many others have top, bottom or even side facing speakers. I did not take this fact into account when I designed my shelves so my audio suffers greatly due to the tight shelving and spacing between radios.

My first idea was too purchase a 12 or more channel mixer and feed the audio from each radio via the mixer to a common amplifier.
This idea would work but gets expensive fairly quick especially after I added in some type of LED indicator for each channel so I could tell by looking, which radio was talking.

Now I'm thinking about just using a cheap pair of amplified stereo computer speakers and using each radios volume control for setting the audio level from each radio.

So that is my question, does anyone have any experience in combining the audio output from several radios together?
I'm assuming I'd need to install some value of attenuating resistor on the signal lead from each radio.
I'm also planning this on the assumption that every radio uses a common negative ground for the external speaker jack. I'll test that before I hook them all together.
If I use a pair of cheap stereo speakers then I'll have two audio channels to work with that share a common ground at the input. I figure I'd need to put up to 8 radios on each channel if I tie them all in.

I guess my other concern is the fact that the cheap speakers all use a low level input and I'll be feeding them from an amplified output on most radios. Some do have headphone jacks that may work better then a full speaker level output.

Any advice on seperating the speaker level audio between each radio as well as attenuating that audio level to something that a cheap pair of amplified computer speakers will handle on thier inputs is greatly appreciated.

I would add a small speaker for each radio but I'm out of space for that idea!

Thanks All
 

AZScanner

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Somewhere in this room. Right now, you're very col
To do this right, you really should get a mixer. A quick google search revealed a 12 channel mixer you can get for $80. You'd need a mess of 1/4" to 3/8" adapters, but that shouldn't cost too much for some cheap ones. They sell for a couple of bucks each. I can tell you from experience however that when you have 12 scanners all going at once, no amount of LED's or funky speaker setups is going to help you make sense of the noise - back in my newshound days I simply fired them all up and waited for a bunch of alert tones or officers yelling before paying much attention.

Here's a link to the mixer I found: Behringer | XENYX 1202 - 12 Channel Audio Mixer | 1202 | B&H

Good luck, let us know what you end up doing.

-AZ
 

kruser

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Thanks for the link and advice.
I do like the idea of using a mixer. This would give me a single control point that could be used when things are out of control and allow me to quickly kill the audio of unwanted chatter.
I guess I'll end up going the mixer route as I could never build something cheaply that also looked good. One thing I will look for though is a mixer with rear panel jacks and maybe even XLR connections that can be switched between high and low level. I have a ton of XLR connectors and inline 1/8" jacks so it would be easy to put it all together.
The rear panel in/out jacks are important as I really would like all wiring to be hidden. Cleaning up the mess of wires I had prior is one of the reasons I started this project!
I also think I've just talked myself out of trying to make use of the XLR connectors due to their size compared to a standard 1/4" plug to 1/8" socket adapter. I bet I already have enough of those to do the job.

I think at this time I've definitely decided to go the mixer route and mainly for the point I stated above about being able to easily kill the audio of each input quickly. I like that thought.

I also know the frustration of trying to monitor more than about two radios at once!
Fortunately for myself, a lot of what I monitor are low traffic channels plus many (like our highway patrol low band) have a distinct tone (hum maybe) or sounds to their transmissions which makes it easy for me to discern what I'm hearing. Put six or so radios on our counties different precinct frequencies however and get them all talking at once and you can forget about trying to make any sense of it as it is a mess!
Oh well, it is fun and that is what it is all about.
 

kskarma

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A possible option for your problem...

I don't know if this would help your situation, but if your shelves and separation would permit, you could cut a small hole in the shelf directly under the speaker. This would eliminate the muffling of the sound and if you had the clearance, a small angled piece of wood or metal could act as a reflector. I understand your situation, but I think it's always helpful if I have multiple speakers spread around the room...or car. This really helps me to separate the different transmissions...and sort of focus my hearing on which ever scanner/speaker is the most interesting.

As a side note, years ago when I worked at a TV station, in the news room we had about 6 speakers on the different local frequencies..(long before trunking of course)...and since most of the news people were not able to tell which speaker was active....we needed a way to visually indicate which 'service' was talking. To do this, we wired small audio transformers across the speaker wires. We wired them so they were in 'step UP' mode...and on the secondary, we attached small neon lamps. Since these lamps took almost no current and would light at about 45 volts, they would light up and pulse in synch with the audio. So when the news people heard something interesting, they could look at the bank of speakers and see that the light over the HiWay Patrol speaker (for example) was on and flickering in synch with the sounds...and they would then know who was broadcasting that particular bit of information.

It was not my idea, but I always thought it was pretty clever...and worked great as well.
 

kruser

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Thanks for the reminder on using a step-up transformer driving neon's.
I used to do this at work many years agon and had forgotten all about this trick.
If I go this route I'll try and change to allow the use of LED's as I seem to recall the flickering neon's causing interference in the HF rigs. I don't remember if we were able to filter it with caps across the neon but I think we did. Boy, that was a long time back!

I have created space for several old small speakers from Motorola cell phone car kit amps I had laying around. These speakers sound great and did not take up a lot of space so I'm down to just 7 radios that need better audio solutions.
I'm really liking the device that chief21 posted a link for.

It will allow 6 radios plus it can be controlled remotely! Just what the doctor ordered!
I wish it had more inputs available though but it will work.
 
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kruser

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Check this out...

New Communications Solutions

Definitely not cheap, but they work GREAT!
Thanks for that link!
I think this is exactly what I need as I'm now down to just 7 radios needing a better audio solution. Surely I can find room for a speaker for the 7th radio.
I also love the fact that this thing can be controlled remotely. It is perfect for my needs but I do wish it had more inputs. I can work around that however.
I'm not worried about the cost figuring what I've spent on all these radios over the years plus what I've spent on custom building the display shelves and the needed RF multi-couplers for hooking them all together!
I could of course build something but it would be very crude and ugly plus it would probably not work!

Also to the others that responded, I really doubt I'd ever have all these things going at one time. If anything, I may have several sitting on various single channels but only one or two actually scanning.
This project is more of an attempt to get them all hooked up and have the ability to just turn any of them on and they just work without the need to swap coax or audio or power leads.
I'm almost there with my project with the exception of the audio on several.
How I overlooked that part I'll never know but perhaps it is old age!

Anyhow, I really appreciate the replies as all were helpful in one way or another.

Maybe one day soon I'll be able to sit down and actually enjoy all the work and time I've put into this project! It has been a fun project and I think I'll be happy when finished.
 

kskarma

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Good Info....and links..

kruser....interesting that you at one time used the step up audio transformers for this purpose. Our receivers were a long ways from the speakers / neons so interference was not a problem...or at least not one we noticed.

And chief21..that nifty device from NCS sure looks like fun... If someone reading this would only buy it for me and let me check it out for a few years, I would really be so grateful...! I like the "Spatial" idea...and at the least would like to see..(hear, actually...) ...how that worked out. Being able to locate the audio 'stereophonically'..is quite the idea.. It would work best if you had separate scanners in a logical Grouping order...so that the same services would appear in the same places all of the time. But...for those of us who have plenty of scanners / inputs / channels, it would be a good scheme. Thanks again for the link...and the loan of $400...!!
 

kruser

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kruser....interesting that you at one time used the step up audio transformers for this purpose. Our receivers were a long ways from the speakers / neons so interference was not a problem...or at least not one we noticed.
The guy that hired me 30+ years ago also did design work on the side for a new line of business back in the day. It was the indoor movie theater business or the beginning of the death of the drive-in.
He worked a lot with lighting and sound systems for some of the local theaters.
He's the one that showed me the trick of using a transformer to light a neon from an audio signal.
I still have a couple old huge tube powered amps that he gave me. I think I could heat my entire apartment with them should I power them up!
Those old amps were set for a 70 volt output but also has regular 4, 8 and 16 ohm taps as well.
Regarding the neon's causing noise in the HF bands, I may be way off on that one as it was 30 years ago! For some reason though, I think I can remember the neon blinking in sync with the static noise on the guys HF radio.
I miss those days. We used to work on all kinds of fun stuff while we should have been doing real work!
 

kskarma

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Interesting thought...

I think your LED idea sounds pretty good. I would wonder about the voltage applied to the LED however. As I recall, the voltage needed to light a neon is something in the order of 45 volts...and I think they will work find up to several hundred volts...since many were used in those simple pocket sized voltage testers. I know the current is very low with the circuit we are discussing..but would a LED be OK with that much?? Hmm, good thing LEDs are cheap!! It might also be helpful to use different colored LEDs for the different scanners...or not...!

I'll be interested to hear if you give this a try..


Thanks for the reminder on using a step-up transformer driving neon's.
I used to do this at work many years agon and had forgotten all about this trick.
If I go this route I'll try and change to allow the use of LED's as I seem to recall the flickering neon's causing interference in the HF rigs. I don't remember if we were able to filter it with caps across the neon but I think we did. Boy, that was a long time back!
 

kc2rgw

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Keep an eye on ebay for 'rack mixer' a lot of home studios and other recording studios use them as do keyboard players. Yamaha makes a really nice one that is common. You can find 12 or 16 channels in a 2U rack mount used for decent prices with patience.

I use a Roland 10ch compact here, but it fills up quickly ;-). Been happy with the Roland, no major RFI issues running a kW output on a regular basis two feet from it.

This is the Roland I got.

Roland U.S. - M-10MX: 10-Channel Battery-Powered Mixer

I was going to build one, but by the time I priced out all the nice ALPS pots, input jacks and components for RF isolation on all the inputs, it added up to what this one cost out of the box.
 

kruser

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Keep an eye on ebay for 'rack mixer' a lot of home studios and other recording studios use them as do keyboard players. Yamaha makes a really nice one that is common. You can find 12 or 16 channels in a 2U rack mount used for decent prices with patience.

I use a Roland 10ch compact here, but it fills up quickly ;-). Been happy with the Roland, no major RFI issues running a kW output on a regular basis two feet from it.

This is the Roland I got.

Roland U.S. - M-10MX: 10-Channel Battery-Powered Mixer

I was going to build one, but by the time I priced out all the nice ALPS pots, input jacks and components for RF isolation on all the inputs, it added up to what this one cost out of the box.
I also considered building but I found the same as you, a higher cost then an already finished product!
I'm fairly certain I'm going with the device that chief21 provided but I also have a backup plan in place.
I looked at mixers and I always loved the looks of them but it seems that most tabletop mixer's with all the neat looking sliders and what not also have the input jacks mounted on the top panel in the rear. I don't really wish to have all the cables sticking straight up although I could get some right angle plugs but that means more cable building. I did find I have a ton of 1/4 phone plugs as well as XLR connectors but no right angle.
So I started looking at rack mount units. They may not be as neat looking as the tabletop design but the functionality is there plus ALL cables go out the rear.
I recall seeing some really nice ones used at work used by various bands over the past 30 years. Should I go the mixer route then it will be a rack mount.
My backup plan is a guy at work. He does DJ stuff for some local clubs plus personal weddings and owns this equipment already. He tells me that he frequents pawn shops and they always have pro audio gear as he bought most of his from pawn shops for very cheap.
So he is checking the area pawn shops for me and will bring a few too me for me to look at. From the way he talks, he knows most of the shop owners and they let him take the stuff out of the shop and bring it back if it does not work out. He's worked with me for about 15 years and I do trust the guy so this may be a cheap way to get one. Now if the pawn shops are legit may be another story! I know several in the area area on the Missouri side of the river are on the up and up but I can't speak for the shops in Illinois which may be were he goes.
I've only ever been in a pawn shop once in my life myself and that was to get rid of a portable camera and recorder that I knew I'd never use again. I'd purchased myself a new all in one camcorder that actually had the tape in the camera. Boy, that was a long time ago! The one I sold was the old type that you hung the bulky recorder over your back along with a huge battery. I remember being fully honest with the guy at the shop and told him then that I did not intend on returning for it so he could sell it right away if he wished. He said he could not due to some law that says they must hold all property for 30 days I think before they can sell. He gave me $200 for the setup and I was only expecting $50 so I was happy. He said he could easily sell it then for between $300 and $400. I know the new one I purchased was over a grand in those days.
The funny part is that I bet I only used it maybe five times and it still sits on a shelf at work to this very day.
Ahh, the good ole days:p
 

elrod

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I think your LED idea sounds pretty good. I would wonder about the voltage applied to the LED however. As I recall, the voltage needed to light a neon is something in the order of 45 volts...and I think they will work find up to several hundred volts...since many were used in those simple pocket sized voltage testers. I know the current is very low with the circuit we are discussing..but would a LED be OK with that much?? Hmm, good thing LEDs are cheap!! It might also be helpful to use different colored LEDs for the different scanners...or not...!

I'll be interested to hear if you give this a try..
Hi Guys,
I see at some point people were using neons to indicate which speaker was active.
I have 5 moto un amped Moto speakers hooked to 5 scanners. I believe the speakers
are 2 or 2.5 ohms. Is it possible to use say 12v leds to show which is active ?
Thank
Chuck
 

kskarma

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This is a job for the "Smoke Test"....!!

I think some experimenting is in order here.. Since the Neon lamps did not have a filament, but merely energized the Neon (this might not be technically correct...so sue me!)...they had a wide voltage range. LEDs are not as tolerant...but...if the audio transformers were sized correctly, this might work fine. The best thing is the parts to give this a try would not cost more than 10 bucks at most.

Model railroad shops have a LOT of different LED stuff...limiting resistors, flashers, various colors, etc...so that might be a good place to find some of the parts. And while the Shack is pretty slim on most components anymore, they do show an audio transformer that might be a good starting place...for $3..!

I think several of us are anxious to see the results of using LED's in this...
 
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