Magnavox horn speakers

[hermitcrab]

I noticed one channel was dull, horns not working on one channel , pulled the back and checked with ohm meter both are open... can you get replacement diaphragms for these? looking at other forums , people have replaced the drivers / diaphragms on these , but none say what they used as replacements?

[electra225]

I have a set of horns out of a Stereo Theater. I can test them to make sure they are good if they would help you. I remember reading where people repaired horns, but I have no idea where to get the parts.

[hermitcrab]

I appreciate the offer , but any horn that is 60+ years old the voice coil membranes are brittle and on borrowed time... searching on other forums , I guess these were made for Magnavox by Heppner ....Parts express has a Pyle 4x10 horn for 20 bucks rated for 20 watts only..., I asked them if these could be used as drop in replacements for a Magnavox , but they have no clue on anything that is not from the modern era ...don't know if I want to spend $$$$ to find out the bolt patterns are different and they won't fit... But in my searching people hook up the horns by themselves testing them and they are loud and will fill a room... going back to my MW I just built ... those horns are barely putting out anything... I think they are dead as well ... they look identical to magnavox horns , except they say Hoffman on them... if I can find a supplier for the diaphragms I could repair four horns right now ...one video shows a guy cutting the styrofoam off the back , then putting in a new diaphragm , but he gives no information on what he used... frustrating ...

[TC Chris]

Is your low output because the crossover is limiting the horns to HF audio? They're not supposed to put out as much noise as the old P.A. reentrant horns, for example. They're tweeters.

Chris Campbell

[TC Chris]

One more thing--you don't need a drop-in replacement. It's easy enough to drill new bolt holes or to make a plywood or Masonite adapter.

Chris Campbell

[electra225]

I don't understand all I know about horn speakers. There are several videos on YouTube on how to rebuild them, doesn't look that hard. The problem is they don't give sources for parts. My understanding is that you check them for continuity, and, if you have some, they are working. They are tweeters, they aren't supposed to be loud. I also understand that the crossover networks cause more trouble than do the speakers themselves. I have been wrong before........

[hermitcrab]

Is your low output because the crossover is limiting the horns to HF audio? They're not supposed to put out as much noise as the old P.A. reentrant horns, for example. They're tweeters.

Chris Campbell

I connected the horns directly to an amplifier and even at max volume you have to be within a couple feet to hear them .. the typical range for these horns are 1000 kz - 14,000 hz there are videos of people playing Magnavox horns on the bench... and they have decent volume , compared to what mine are doing..

[electra225]

Now, I'm not a horn speaker expert by any means, but aren't those diaphrams "freeze or fry", good or bad, open or not? Can they be "partly bad", in other words, they work, but not "enough"? Also, if you are feeding them full frequency audio, maybe they can't handle that. Maybe they only work on certain of the higher frequencies. I don't know, and find this topic of particular interest. I've never really studied horn speakers before.

When you take a car horn apart to get rid of the mud dauber's nest, if you work just the diaphram part all is does is vibrate or buzz. When you put it back onto the horn assembly, then it is loud like it should be. If I understand the theory on audio horn speakers, the diaphram is surrounded by a coil, doing the job of a voice coil in a cone speaker. This diaphram vibrates in a chamber that "collects" the sound, then feeds it to the horn for amplification, so you can hear it. If the voice coil in a cone speaker was open, you wouldn't get any sound. My understanding is the same thing holds true for horn speakers. I reckon you could have that coil/diaphram assembly sticking or hanging up, which might make it quieter than it should be. Comments, criticism? Remember, I've been wrong before.....

[William]

I have no clue, but what Greg says makes sense and if it were totally dead then it should not make any noise, but it does, just faint. Also, if the voice coil was bad but not dead would it not sound like a paper speaker, sounding fuzzy and the horn would amplify that sound?

Bill

[electra225]

It has happened in the past where speaker cones get hard and brittle and refuse to move like they should. Can the diaphram in a horn speaker do the same?

[TC Chris]

Or maybe those horn have mud dauber nests or mouse mansions inside them....

Chris Campbell