Switch to full style
A place for discussion general audio, music and related topics.
Post a reply

Been thinking about the environment inside a speaker cabinet

July 29th, 2020, 4:27 pm

The area near and around speaker drivers inside the cabinet must be high in EMF due to the magnets.
Why wouldn’t be advisable to shield the crossover and the wires inside the cabinet

Re: Been thinking about the environment inside a speaker cab

July 29th, 2020, 4:47 pm

Pelliott321 wrote:The area near and around speaker drivers inside the cabinet must be high in EMF due to the magnets.
Why wouldn’t be advisable to shield the crossover and the wires inside the cabinet

Actually it is a static magnetic field that is pretty much focused on the voice coil of each driver. It is essentially a closed circuit. I seriously doubt there is any effect to be concerned about. But EMF it is not.

The reason some hi-end manufacturers put the crossover outside is to get away from enclosed severe acoustic issues that can interact with the crossover parts that may be influenced by mechanical vibrations.

Re: Been thinking about the environment inside a speaker cab

July 29th, 2020, 5:09 pm

Capacitors are potentially microphonic (in fact a condenser microphone is a capacitor).

Inductors will have a electromagnetic field, and can interact (couple) with each other, and I suppose, can interact with a speaker voice coil (or vice versa) if sufficiently close and the field strong enough, though that may be pretty low order.

So yes, best to get the crossover out the box if practicable, though this is rarely done for anything other than DIY speakers.

David

Re: Been thinking about the environment inside a speaker cab

July 29th, 2020, 11:05 pm

David McGown wrote:Capacitors are potentially microphonic (in fact a condenser microphone is a capacitor).

Inductors will have a electromagnetic field, and can interact (couple) with each other, and I suppose, can interact with a speaker voice coil (or vice versa) if sufficiently close and the field strong enough, though that may be pretty low order.

So yes, best to get the crossover out the box if practicable, though this is rarely done for anything other than DIY speakers.

David

10-4

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 8:48 am

I agree that the mechanical vibrations are a problem for the crossover. At the same time I have never seen anyone physically securing the wires inside the box so they do not flop around.
I am also thinking about using different wires for the different drivers.
Small litz for the tweeter, a medium gauge for mids and large solid wire for woofer

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 9:37 am

Pelliott321 wrote:I agree that the mechanical vibrations are a problem for the crossover. At the same time I have never seen anyone physically securing the wires inside the box so they do not flop around.
I am also thinking about using different wires for the different drivers.
Small litz for the tweeter, a medium gauge for mids and large solid wire for woofer

Actually hard-wired interconnecting wiring is virtually not there. Not to worry. Say the average hook-up wire in a speaker is about 1-foot long -- the DC resistance is a mere .0064 ohms. The self-inductance again is not a big deal at .58-uH.

You have bigger fish to fry. Quality of crossover components and crossover design.

In terms of the wiring -- just simply use-twisted pairs to connect the drivers to the crossover.

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 10:30 am

I think it should be a wiring harness shielded against EMF with some of the new aerospace products out there. I found a heat shrink with foam lining impregnated with EMF shielding that would act as a dampening agent also. make up the harness and securely to the inside of the box.
Someone here said "the devil is in the details"
Then move the Xover outside the box.

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 11:34 am

Pelliott321 wrote:I think it should be a wiring harness shielded against EMF with some of the new aerospace products out there. I found a heat shrink with foam lining impregnated with EMF shielding that would act as a dampening agent also. make up the harness and securely to the inside of the box.
Someone here said "the devil is in the details"
Then move the Xover outside the box.

You keep focusing on "EMF." That's not what is going on in a loudspeaker. It is not an issue. To be clear -- here is how it is described in the literature:

There are two types of EMF. Low-level radiation, also called non-ionizing radiation, is mild and thought to be harmless to people. Appliances like microwave ovens, cellphones, Wi-Fi routers, as well as power lines and MRIs, send out low-level radiation.

High-level radiation, called ionizing radiation, is the second type of radiation. It’s sent out in the form of ultraviolet rays from the sun and X-rays from medical imaging machines.

EMF exposure intensity decreases as you increase your distance from the object that’s sending out waves. Some common sources of EMFs, from low- to high-level radiation, include the following;

Non-ionizing radiation:

microwave ovens
computers
house energy meters
wireless (Wi-Fi) routers
cellphones
Bluetooth devices
power lines
MRIs

Ionizing radiation:

ultraviolet light
X-rays

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 11:57 am

A solution in search of a problem....

Re: Been thinking about the environment inside a speaker cab

July 30th, 2020, 12:18 pm

Roscoe Primrose wrote:A solution in search of a problem....


Right there!

From an engineer's perspective, we are talking about EMF influence on the pico, nano or micro-watt level, whereas we are supplying signal to the speakers several orders of magnitude above this. Any possible effect will be swamped out by the amplified music signal. It might be something really useful for source components, like phonostages. That being said, if amplifier driving the speaker is high gain and has a global feedback loop from the output terminal of the amp, there might be some injection of noise that can occur and is amplified.

The ham radio operator a few houses down from me have kept me on my toes over the years dealing with RFI issues, but fortunately, that now seems to be confined to listening to phono. I get less noise from low impedance moving coil, than high impedance moving magnet, even though the latter is 15 to 20dB higher signal level from the cartridge. No problem with digital (line level) inputs. When he starts up his rig, then I just switch sources and keep happy.

David
Post a reply