Speakers.. push or pull?

BASSKADET · #1 12-20-2010, 09:21 AM

My Aggie DB210 I thought was being overdriven at too low a volume. I took the grill off and plucked the open E and the speaker retracted in. I thought speakers were supposed to push air?

m.oreilly · #2 12-20-2010, 09:29 AM

me too...

Bassamatic · #3 12-20-2010, 09:31 AM

Speakers move in both directions at the same frequency as your string. They push AND pull - this is the nature of sound. You're just not seeing the "out" as much as the "in". Touch it lightly while it is vibrating and you'll see this.

BASSKADET · #4 12-20-2010, 09:52 AM

It's moving in a whole lot more than out. Hardly moving out at all.
Is it possible the polarity is reversed?

greenboy · #5 12-20-2010, 09:54 AM

It's obviously your technique.

BASSKADET · #6 12-20-2010, 09:57 AM

Quote:

Originally Posted by greenboy

It's obviously your technique.

Funny

unclejane · #7 12-20-2010, 09:59 AM

Quote:

Originally Posted by BASSKADET

My Aggie DB210 I thought was being overdriven at too low a volume. I took the grill off and plucked the open E and the speaker retracted in. I thought speakers were supposed to push air?

That's actually just instability in the power supply of the amp. You'll get a little DC at the output in some amps when they're overdriven as the power supply voltage drops and then attempts to recover.

The low E is about 44hz, which is only visible at the speaker cone as the blur...

Nothing to worry about, really...

LS

jamievespa · #8 12-20-2010, 10:01 AM

With low frequencies especially, watching speaker cones looks a lot like spinning wheels on cars where they look like they're spinning backwards.

It's just the 'refresh rate' of your eyes is seeing the speaker when it is in the 'inward' position.

You can do an experiment with a tone generator and a strobe light and a speaker and you can set the strobe frequency just right to watch the speaker moving in and out.

Hope this helps

billfitzmaurice · #9 12-20-2010, 10:11 AM

Quote:

Originally Posted by BASSKADET

It's moving in a whole lot more than out. Hardly moving out at all.

That's only possible with a driver that's seriously AFU. I'd bet it's an optical illusion.

greenboy · #10 12-20-2010, 10:15 AM

Interesting things can be done with an adjustable strobe light pointed at a cab. And changing what notes you are watching. So much of this stuff is perceptual rather than actual, as jamievespa notes.

Don't buy the bit about instability of amplifier.

E1 is 41.2 Hz btw - here's some frequencies (third chart down) - : http://lowdownlowdown.com/greenboy/D...sfrequency.htm

john m · #11 12-20-2010, 10:20 AM

If you doubt any of the above statements,
temporarily reverse the polarity somewhere (like an old speaker cord) and see what happens.

Be sure to put it back so that all of the speaks in your system are in phase.

jm

BassmanPaul · #12 12-20-2010, 10:29 AM

Connect a 9V battery across the tip and sleeve of your speaker cable. You should hear a healthy clunk from the cabinet and see the cones move. All the speakers should move in the same direction. It would seem that most manufacturers have is so with the positive battery terminal connected to the tip the cones move out away from the magnet structure.

M0ses · #13 12-20-2010, 10:31 AM

It can't be moving in more than out! The speaker is stationary.

PhiDeck · #14 12-20-2010, 10:32 AM

OP: Any time you encounter an unintended half-wave rectifier you should consider the presence of an unauthorized diode. Do you have any prankster friends who own a soldering iron?

Crockettnj · #15 12-20-2010, 10:35 AM

Quote:

Originally Posted by PhiDeck

OP: Any time you encounter an unintended half-wave rectifier you should consider the presence of an unauthorized diode. Do you have any prankster friends who own a soldering iron?

EE humor... gets ya every time!

billfitzmaurice · #16 12-20-2010, 10:46 AM

Quote:

Originally Posted by M0ses

It can't be moving in more than out!

Yes, it can, if the voice coil isn't centered in the magnetic field with no signal is applied. That could occur with a driver that was improperly assembled.

BASSKADET · #17 12-20-2010, 10:51 AM

Quote:

Originally Posted by billfitzmaurice

That's only possible with a driver that's seriously AFU. I'd bet it's an optical illusion.

If I pluck the E string up and out the speaker moves in. If I pluck the string straight out it does not do this it moves out a little.

I did do the 9V and it does move out with a click.

greenboy · #18 12-20-2010, 10:53 AM

For starters, do some other notes like I mentioned above.

BASSKADET · #19 12-20-2010, 10:55 AM

Quote:

Originally Posted by greenboy

For starters, do some other notes like I mentioned above.

More prevalent in the lower range like F, F# G on the E.

At Any rate I have Aguilar calling me back this afternoon. I might also want to check the pre tubes to see if they got bumped in the shipping.

My amp settings are pre 10 o'clock eq flat and the master 1 O'clock. And I get the fuzz tone(distort).

greenboy · #20 12-20-2010, 10:58 AM

Does it sound right? Then you are good. Short of actually measuring this stuff with tools and skillset you do not possess, you have not a chance of determining what's what absolutely anyway.