vocal megaphone effect

[idy]

I have not found a diy for this. I love the sound when I see people using an actual megaphone, but want to build a little device to use with a wireless headphone mic. Mostly a midrange band pass? I have tried graphic eqs and not found the sound I am thinking of. Not narrow enough? Some kind of distortion necessary? Maybe I should build one of those harmonic energizers...?

[11-90-an]

https://smallbusiness.chron.com/megaphone-effect-radio-ads-32497.html

perhaps try to emulate the loud feedback/oscillation noise too when volumes reach a certain level...

[ThermionicScott]

Pass your signal through a Metal Zone with the Bass turned all the way down.   

[merlinb]

Megaphones have terrible dynamic range, so I would have thought you could get close with a steep 300Hz low-cut filter, and a steep 5kHz high-cut filter (similar to telephone effect), then adding a soft clipping stage? I would try filter > clip > filter again

[Fancy Lime]

Way back in high school, we used a cheap microphone with a 1/4" plug into a Boss PW-2 into a little practice amp, which we then miked for vocals. That sounded very much like a really bad bullhorn. Check out Tim Escobedos Lofo Mofo for a simpler solution.

Andy

[marcelomd]

The singer in my old band had a megaphone. I loved that.

We had two cars, and, on our way to and from the studio, often would talk trash to each other using the megaphone in traffic.

Good times!

[iainpunk]

Way back in high school, we used a cheap microphone with a 1/4" plug into a Boss PW-2 into a little practice amp, which we then miked for vocals. That sounded very much like a really bad bullhorn. Check out Tim Escobedos Lofo Mofo for a simpler solution.

Andy

i love the PW-2, i had one on loan, it comes quite close to the HM-2 if you set it right in front of an already driven amp.

i guess a good way to do lofi is using a single sided clipper and an (active?) bandpass filter. a bit of crossover distortion is also a good tool
even with a huge amount of distortion, like a big muff, your voice will remain somewhat recognizable and understandable, you can really go nuts.

cheers, Iain

[anotherjim]

An ISD1820 voice/memo chip might be useful. It can be set in playthrough mode where you have an input AGC and low pass filter always active and don't bother with the recorder side. A cap sets the speed response of the AGC and a resistor sets the filter via the record time pin. The input cap to the preamp would set the bass response.

[garcho]

How about a multiple feedback band pass and a LM386? You could throw some gating diodes in there, too, for extra crappiness.

[iainpunk]

How about a multiple feedback band pass and a LM386? You could throw some gating diodes in there, too, for extra crappiness.

i have an idea, do you like oscillations?

[iainpunk]

its only a building block, not a full design yet:


the 386 is a buffer until the diode threshold is overcome, then the part over the threshold gets a 21dB boost of 1kHz
an other opamp can be used, depending on the incomming signal, a boost could/should be placed up front.

i think this is going to be part of my newest iteration of my death metal pedal projects!

cheers, Iain

[idy]

Thanks, I think we've got some places to start...
My attempts previously led me to think that fuzz/od/distortion didn't really do it (for me), and feedback from compression is not desired.  Real megaphones compress, but feedback is controlled by the directionality of the horn. I'm looking for tinny, lo-fi, distant, disembodied, not monstrous and harsh.

The first suggestion from 11-90 suggests steep cut (everything below 90hz?) and a boost peak around (2k?) and some kind of compression/distortion. Maybe better and simpler to think "limiting" than "compressing" and diodes would seem right. But maybe some opts action...

[11-90-an]

Check out Tim Escobedos Lofo Mofo for a simpler solution.

@idy you should try this ckt, really simple to do on the breadboard and should give "satisfactory" results...

[PRR]

....get close with a steep 300Hz low-cut filter, and a steep 5kHz high-cut filter...

That's one way. But 300Hz is a BIG megaphone. And 5KHz may be hit-or miss (uncontrolled peaks/dips).

You can cut bass at 1kHz or so. Since most speech Power is below 1KHz, you must cut SHARP so (as you say) the bass does not bleed and fill-up the empty octaves. A lot of talking got done on 3kHz (or worse) max telephones, and some of those very sharp cutoff.


https://www.fishercom.xyz/voice-channels/the-human-voice.html

Some of us in Bell territory grew up on Bell 500 phones (introduced 1951). The one before, the 302, my parents remember, but mostly from old movies. That was THE Bell telephone for much of the early 20th century when telephone growth was phenomenal. It looks like a bell-ring but was intelligible enough. To-the-ear bass response is much better than horn in open air so it won't toe-out at 300cps but drop at 1kc.

[iainpunk]

Check out Tim Escobedos Lofo Mofo for a simpler solution.

@idy you should try this ckt, really simple to do on the breadboard and should give "satisfactory" results...

doesn't that basically do the same as the range master? clip asymmetric and take off all the bass!

cheers, Iain

[Rob Strand]

Quote from: merlinb on Today at 03:33:46 AM

    ....get close with a steep 300Hz low-cut filter, and a steep 5kHz high-cut filter...


That's one way. But 300Hz is a BIG megaphone. And 5KHz may be hit-or miss (uncontrolled peaks/dips).

The basic ideal of what merlin said seems OK but I agree with you on the frequencies.   A lot of megaphones quote 500Hz as a cut-off but even that might be too low for an exaggerated effect.

I suspect the roll-off doesn't need to be too high a rate to work.  A higher Q high-pass filter would help add some of the peaking you see near the lower cut-off of crudely made horns.   

However as far as a filters goes there's more to it.   There's a 6dB diffraction step that needs to be added on which is going to be complex since the megaphone has a weird shape and your head and torso come into the equation.     Perhaps a 4 to 6dB treble boost from 1.5kHz to 3kHz would be a good start.   Smaller size horns are going to mean pushing those frequencies up and larger horn pushing them down.    It definitely will help get that abrasive "small" sound.

[ElectricDruid]

I suspect the roll-off doesn't need to be too high a rate to work.  A higher Q high-pass filter would help add some of the peaking you see near the lower cut-off of crudely made horns.   

+1 Agree. The filters don't need to be extraordinary. If you put a simple 2-pole 12dB/oct highpass at 1KHz, you've got -3dB down at 1KHz (the cutoff freq), but 12+3=-15dB at 500Hz, and -27dB at 250Hz. So you're in the right ballpark. A bit of boost at 1KHz due to a higher Q might give the sort of midrange, peaky sound you often get with those things, so that's worth playing with.

Edit: Bleedin' autocorrect!

[Rob Strand]

If you put a simple 2-pole 12dB/oct highness

2nd order would be a good minimalist starting point.

megaphone 2012


megaphone 2025  (Iphone 16? comes with free backpack)

[Fancy Lime]

If you put a simple 2-pole 12dB/oct highness

2nd order would be a good minimalist starting point.

megaphone 2012


megaphone 2025  (Iphone 16? comes with free backpack)

An iPhone that comes with free accessories? Do they deliver via flying pig?

[11-90-an]

megaphone 2025  (Iphone 16? comes with free backpack)

Haven't you heard? the iPhone 12 won't have a charger in the purchased box. At 2025 there's bound to be on iPhone in the box as well... iBox 1 anyone?