Light Bulb Attenuator. Anyone done it?

[jon the art guy]

Just curious.

For those who don't know what I'm talking about, Apparently you can just splice a light bulb base into a speaker wire and screw in a bulb of double your amp wattage, and the bulb will light up and pull signal out in the process. It's also suppose to compress in an odd way. I don't have a proper amp I can dissect with me right now, but I'd like to hear people's opinions on the sound of it.

 

[dominus]

Re: Light Bulb Attenuator. Anyone done it?

 

[GuitarStv]

Re: Light Bulb Attenuator. Anyone done it?

No, but it sounds cool! Going on my to-do list.

 

[Grenade]

Re: Light Bulb Attenuator. Anyone done it?

:haha:

 

[Artie]

Re: Light Bulb Attenuator. Anyone done it?

It's also suppose to compress in an odd way.

A light bulb is damn near a dead short when it's cold. But its resistance rises rapidly when it comes on. (Ever notice that a bulb tends to blow at turn-on?)

So, on a hard voltage spike, the bulb will suck all of the current, then let go as the filament warms. I'm not positive about this, but I believe that's the principal behind some of the great old "optical" channel strip compressors such as the Universal Audio LA-2 and similar. Although, they use the light-bulb "delay" to operate a photo-cell.

 

[uOpt]

Re: Light Bulb Attenuator. Anyone done it?

The bulb is in series?

Might be a bad idea for a tube amp. I don't think you have any control over the resulting effective impedance. If you don't have enough resistance the output transformer runs effectively empty and might be damaged.

 

[Artie]

Re: Light Bulb Attenuator. Anyone done it?

I assume the bulb is in parallel or the "compression" effect wouldn't happen. Series would sound awful.

Reverse compression. A loud "pop", followed by low volume.

 

[Empty Pockets]

Re: Light Bulb Attenuator. Anyone done it?

Sounds like a bad idea left to somebody with more time than sense and / or money.

Plug your guitar into your amp and make music. If your amp sounds so bad that you want to plug it into a lightbulb, you should buy a different amp.

 

[DankStar]

Re: Light Bulb Attenuator. Anyone done it?

Jam a christmas strand bulb into the speaker jack. Just don't use the blinking one.

 

[GuitarStv]

Re: Light Bulb Attenuator. Anyone done it?

Sounds like a bad idea left to somebody with more time than sense and / or money.

Plug your guitar into your amp and make music. If your amp sounds so bad that you want to plug it into a lightbulb, you should buy a different amp.

Someone needs to look up what an attenuator actually does before commenting.

 

[kilphody]

Re: Light Bulb Attenuator. Anyone done it?

The bulb is in series?

Might be a bad idea for a tube amp. I don't think you have any control over the resulting effective impedance. If you don't have enough resistance the output transformer runs effectively empty and might be damaged.

+1
Save the light bulb in series for the dim-bulb for dimwits test after a build.lol
Just turn the amp down. Don't fry it.
PC

 

[trevorus]

Re: Light Bulb Attenuator. Anyone done it?

These can be used on the AC in circuit, which can provide sag on transients. They also use it for testing amplifiers that are blowing fuses to limit current to give a little more time to diagnose. I've seen them used on little Valve Junior amps, but I would really want to be quite aware of whats going on electrically before I just throw a bulb inside an amps normal operating circuitry.

 

[Animal]

Re: Light Bulb Attenuator. Anyone done it?

Don't waste a perfectly good bulb!

 

[Grenade]

Re: Light Bulb Attenuator. Anyone done it?

A light bulb is damn near a dead short when it's cold. But its resistance rises rapidly when it comes on. (Ever notice that a bulb tends to blow at turn-on?)

So, on a hard voltage spike, the bulb will suck all of the current, then let go as the filament warms. I'm not positive about this, but I believe that's the principal behind some of the great old "optical" channel strip compressors such as the Universal Audio LA-2 and similar. Although, they use the light-bulb "delay" to operate a photo-cell.

This is how the automotive bulbs work in our Peavey 215 PA cabs. Unfortunately they are 12 volt 25 watt and a PITA to find.

 

[crusty philtrum]

Re: Light Bulb Attenuator. Anyone done it?

If your amp has some form of selector for the output impedance, look at it closely. It will allow you to select between at least two of either 4, 8, or 16 Ohms, either via a switch or dedicated output socket(s). Do not use a light bulb instead of a loudspeaker in this type of amp.

If you see an amp that has, for example, three speaker output sockets, labelled '8/16/Light Bulb', or a switch labelled '4/8/16/Light Bulb', by all means use a light bulb.

Follow these directions and you won't have any problems.

 

[MrTondo]

Re: Light Bulb Attenuator. Anyone done it?

Well I guess you can attenuate lightbulbs. I have never done it to be honest, I have seen it done though.

It all dependens on the lamp type though, some will work, some won't. One thing you will surely need to attenuate lightbulbs in a government approved way is a dimmer switch.

Hope that helps in purchasing a light bulb attenuator.

 

[Ascension]

Re: Light Bulb Attenuator. Anyone done it?

My ol buddy and long time personal amp tec Sam Timberlake has been doing this for years with his Samamps.

 

[jon the art guy]

Re: Light Bulb Attenuator. Anyone done it?

Ah, he runs them in before the output tubes. That makes way more sense than before the speakers.

Sent from my DROID RAZR using Tapatalk

 

[zzmoore]

Re: Light Bulb Attenuator. Anyone done it?

I am still confused about where the bulb is.
Cannot run a 120 volt bulb off of 200-400 VDC for very long.
So where are the bulb(s) located.?
Is it in series with the mains supply.? What does that do to the heaters.?
Anyway...I guess I have no idea what this is about.
Thank You

 

[GuitarStv]

Re: Light Bulb Attenuator. Anyone done it?

Wait, isn't this what THD does with their Univalve amps?