Author Topic: Model 500 Echo  (Read 934 times)

Offline mmd

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Model 500 Echo
« on: January 06, 2012, 08:51:36 PM »
I gave my Dad my model 500, which is now used in the livingroom, and works great.

It however has one slight problem.  When I call him, and he picks up, I can hear my own echo from that phone for the first 10 seconds before it fades away and goes to normal.

What could be causing this?  I tried my 302 on this line, and it doesn't do this.
Brandon
Western Electric 302, 500

Offline GG

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Re: Model 500 Echo
« Reply #1 on: January 07, 2012, 08:00:35 AM »


I'm willing to bet your dad is on a Comcast line or some other VOIP line. 

In that case, the 500's louder transmitter output (as compared to the 302; this being one of the key aspects of the 500 design, to enable it to be used on longer loops) is probably causing the echo to begin with, and the Comcast or whoever's ATA or possibly central office switch, is using echo canceling, which takes a little while to kick in on each call. 

One possible fix for this is to put some kind of dropping resistor in parallel across the R and B terminals on the 425 network block, to reduce the transmitter output to the same level as the 302.  Finding the correct value of resistor would take some doing, to get the volume down to exactly the right level. 

One way to do this without a bunch of test equipment, might be to take a variable resistor ("potentiometer") at about 25 K, and solder two leads onto it (center contact and one of the outer contacts), connect them to R and B, and then quickly make a series of brief phone calls to another phone (e.g. your cellphone) whilst setting the potentiometer at various points to see what works best.  You'll need to have good enough ears to be able to remember the loudness of the audio from each test, starting with the 302 as a reference point.  Then when you find the correct setting, use an ohmmeter to measure it, and go buy a resistor (rated 1/4 watt or higher) at a value that's as close as possible to the one you measured. 

Note, the sidetone level on a 500 set in normal use is a tad lower than on a 302, so it's also possible that someone who is used to a 302 will tend to speak a little more loudly on a 500 in order to hear the same amount of sidetone.  Speaking more loudly will also produce the result of louder output and greater echo. 

Alternately you could just "get used to it" and think of it as one of the "cute" transmission artifacts of "modern" (VOIP) telephony.  If you internalize the worldview that real life has become dystopian science fiction, everything makes more sense:-)

Offline mmd

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Re: Model 500 Echo
« Reply #2 on: January 07, 2012, 07:59:02 PM »
We do infact use VoIP.  I use Vonage actually, and the only MTA that even has rotary support (V-Portal).  It services two lines (other line is my personal line, which is the 302..)

I'll try these things to see if it resolves it.
Brandon
Western Electric 302, 500

Offline Phonesrfun

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Re: Model 500 Echo
« Reply #3 on: January 07, 2012, 08:50:06 PM »
I don't think it has anything to do with the phone you have hooked up.

Starting about one year ago, the same thing happened on my Vonage service.  Every time someone called my Vonage number, they got an echo for about the first 10 seconds or so.  I also noticed this when I called home to talk to my wife.

I just got used to it.

It happened whether the phone I used was a 500, a 2500, a 302, and even a modern cordless that is only about 6 months old.

I think it is how the Vonage router is provisioned with your cable or DSL service, but I doubt if there is anything you can do.

The way I solved the problem was that a couple of weeks ago my cable company called and offered me a deal better than Vonage, so I took the deal.  They ported my number over, and now, no more echo!

-Bill G