"Sweetening" a telephone hybrid

[ChiefOperator]

Folks,

At an AM, the on air callers sound typically muddy and the levels are over the place. The hybrids have AGC, but the function doesn't seem to work well.

I'd like to level and improve the audio. I'm thinking some compression and EQ would definitely help. Before I start making changes, how have you folks done this successfully?

To do this, I'm thinking about using a dbx 286a mic processor (I won't be using the preamp section).
Given its compression and vocal controls, I'm thinking it would help.

THANKS!

 

[JZ6563]

Are we talking about an POTS hybrid here? If so, I have found that with these hybrids, their ability to yield a quality output can be greatly impacted by their ability to null out the line. Try to get nice clean runs of twisted pair directly back to the CO, little to no flat lineif possible. Watchout for paralleled phone sets or even other house phone systems on your studio lines. These can load and greatly tweak the charactoristics of the line that the hybrid is trying to null against. You can parallel stuff after the hybrid if need be, but keep it clean going in if possible. The cleaner the line, the better the null. A better null I have found tend to give you a better caller sound and more consistent output.

Once you get a really good null you may still want to process the caller, but I would concentrate on the null first and then the processing. I have used dbx, valley and aphex processors on caller outputs and all do a pretty nice job as long as the null is good.

JZ

 

[Play Freebird]

At an AM, the on air callers sound typically muddy and the levels are over the place. The hybrids have AGC, but the function doesn't seem to work well.

I'd like to level and improve the audio. I'm thinking some compression and EQ would definitely help. Before I start making changes, how have you folks done this successfully?

I've never used a DBX 286a for this pupose, but it's probably worth a try.

One problem I've noticed with telephone audio on certain FM stations: The voice peaks can hit the main processor's clipper quite hard, but due to bandpass limitations of the phone line, there's very little natural audio energy above 3 kHz to mask this distortion, as would normally be the case with music or local mic sources. Therefore, muddy callers can also sound very raspy over the air.

Seems to me there's a product niche for a DSP phone audio processor that would add some "controlled" harmonic distortion to muddy caller audio and enhance the fullness.

 

[ChiefOperator]

Thanks for the replies. Yes, I'm talking about a POTS hybrid, one is digital and the other is analog (soon to be replaced).

 

[TomT]

On our incoming POTS audio we have an inexpensive eq (an ART multiband: $99) and an Orban 424. This is just incoming off a coupler for remotes, but you could use the same setup with a hybrid on the caller audio.

Impractical, of course, to eq every call on a live show, but the ART has proved very useful for us in eliminating hum and/or hiss on bad phone lines. Nothing more irritating than a 2 hour long sports broadcast with a bad hum in the background.

 

[Chuck]

On our incoming POTS audio we have an inexpensive eq (an ART multiband: $99) and an Orban 424. This is just incoming off a coupler for remotes, but you could use the same setup with a hybrid on the caller audio.

Impractical, of course, to eq every call on a live show, but the ART has proved very useful for us in eliminating hum and/or hiss on bad phone lines. Nothing more irritating than a 2 hour long sports broadcast with a bad hum in the background.

We're using a Furman 31 band EQ (we had it) and a dbx 266 compressor/limiter/gate. Both are two channel devices. They are connected to a pair of JK Audio "Inkeeper" digital hybrids. It really helped, especially when you have a noisy phone line at a remote location. You can get rid of a lot of unwanted noises with this set up.

I've never thought of using a dbx mic processor for this application, but I see no reason why it wouldn't help.

 

[wgliradio]

I'm using an Aphex Dominator to catch peaks (FM). Works VERY well, it's quick enough to get in, control the audio and get out. The AGC in the Telos is set very conservative and it works like a charm!

 

[Sgeirk]

We use a single Texar Prism. Works OK. We still have level issues, though, but I think it's the null...good advice. New job for tomorrow.

 

[Dndsh237]

I have found that for the phone broadcasts I deal with, that a simple, single band AGC between the hybrid and the console, works very well to balance all the levels and enhance the audio quality a bit.

Of course this is strictly for sports broadcasts, not talk shows or anything like that.

 

[dtube1]

Tonally, get an Aphex 204 aural exciter. They are relatively cheap (especially on Ebay) and can make a phone call sound pretty darn good. Place it AFTER a compressor with a low threshold, 2:1 ratio, and 75ms release.
-D

 

[Play Freebird]

Tonally, get an Aphex 204 aural exciter. They are relatively cheap (especially on Ebay) and can make a phone call sound pretty darn good. Place it AFTER a compressor with a low threshold, 2:1 ratio, and 75ms release.
-D

Good idea -- this will replace some of the vocal harmonics that are filtered out by the narrow bandpass of a phone line.

Telos, could you add an option like this to a future DSP hybrid? With more FM stations running news and talk formats, and AM stations simulcasting on FM translators, there's a greater need for improved phone audio.

 

[Chuck]

Tonally, get an Aphex 204 aural exciter. They are relatively cheap (especially on Ebay) and can make a phone call sound pretty darn good. Place it AFTER a compressor with a low threshold, 2:1 ratio, and 75ms release.
-D

Good idea -- this will replace some of the vocal harmonics that are filtered out by the narrow bandpass of a phone line.

Telos, could you add an option like this to a future DSP hybrid? With more FM stations running news and talk formats, and AM stations simulcasting on FM translators, there's a greater need for improved phone audio.

It is a good idea. In fact, you might try a BBE exciter. They are cheaper than the Aphex and produce a similar (but not quite the same) effect. I think you can buy their basic version for less than $100 brand new. I know that BBE offers their chip to various OEM manufacturers. I have a TV that has it built in. I’ve even seen it on some boom-boxes, so it couldn't cost much to add. Perhaps it would be a very cost effective improvement that could be made for various hybrids. Manufacturer’s take note!

 

[ChiefOperator]

Thanks for all the replies...

The Aphex 204 sounds interesting. You prefer the Aphex 204 to a regular EQ? I might have to give it a try..

 

[dtube1]

Yes. The Aphex unit creates harmonics above and below the 300-3k audio from the POTS line. It really improves the perceived fidelity. Be warned though that It will take some experimentation to find the sweet-spot, though.
-D

 

[Dndsh237]

Yes. The Aphex unit creates harmonics above and below the 300-3k audio from the POTS line. It really improves the perceived fidelity. Be warned though that It will take some experimentation to find the sweet-spot, though.
-D

As is often the case with any equipment containing knobs, buttons and lights. ;D

 

[Fenway Frank]

Just a crazy thought here, before you start adding more gear to solve the problem, why not make 100% certain that the Hybrids are working properly? They could easily have taken a lightning hit or some sort of surge. If they are old units, it may be time to look at something newer. If they are new then hit the tech support line (of whichever brand they may be). Most manufacturers are more than happy to help you get happy about what you just bought.

 

[ChiefOperator]

All the gear is working fine and doing the best it can, given the limitations of POTS lines. I was simply looking at established methods to "sweeten" the audio quality...

Thanks...

 

[petsy]

Adding to an old thread here. I tried something today that you might be interested in trying yourself. Many phone hybrids can output either a line or mic level signal. We took an Electro Harmonix 12AY7 mic preamp (really good pre for the money) and ran the hybrid at mic level through it. With the right setting, it added that little bit of extra warmth to the signal that I think you might be looking for. Might be a good idea to go this route instead as the 12AY7 is a really handy pre for regular recording as well so you won't be buying a unit that doesn't work for anything else but this one application. Of course you can try it with any mic preamp you might have lying around but I'm fairly sure a "vintage" type pre would be the best option.