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10-13-2011, 02:23 PM
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GBX Member #1 | | Join Date: Jun 2011 Location: London, Ontario, Canada | | | Testing Impedance
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I'm trying to find out the impedance of the 2, 15 inch speakers in this GBX Amp. When I removed one speaker, and put a Mutimeter on it, it read around 6 ohms. Does this signify leaning toward 8 ohms?
The Meter is an older, swing arm style, not digital.
The purpose is to re-driver the Cabinet.  |
10-13-2011, 02:28 PM
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GBX Member #1 | | Join Date: Jun 2011 Location: London, Ontario, Canada | | If someone here could steer me toward ANY chance of finding Grill Cloth Replacement for a GBX 2, 15...PLEASE let me know.  |
10-13-2011, 02:29 PM
| | | | Re-driver the cabinet? Replace the speakers? Whats the overall impedance of the cab and what is the number of speakers in it? A multimeter cannot test impedance, it can only test resistance. Or rather most multimeters anyone would care to buy
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10-13-2011, 02:31 PM
| | Registered User | | Join Date: Jul 2007 Location: Dallas, TX | | | If it reads 6, it's an 8 ohm driver. Most likely a 4 ohm cab with 2 of them. Download WinISD to find out what drivers are suitable to the cab. measure the cabs internal volume first.
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10-13-2011, 02:32 PM
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Originally Posted by 4StringShooter  If someone here could steer me toward ANY chance of finding Grill Cloth Replacement for a GBX 2, 15...PLEASE let me know. | Look at Parts Express, Antique Electronic Supply, Mojotone, Gerald Weber,..... |
10-13-2011, 02:33 PM
|  | Registered User | | Join Date: Nov 2007 Location: boston, ma | | | If you're testing DC resistance and getting around 6 ohms it's probably an 8 ohm speaker. In DC, the meter should read about 3/4 of the speaker's AC impedance. |
10-13-2011, 02:35 PM
| | | Quote:
Originally Posted by 4StringShooter I'm trying to find out the impedance of the 2, 15 inch speakers in this GBX Amp. When I removed one speaker, and put a Mutimeter on it, it read around 6 ohms. Does this signify leaning toward 8 ohms?
The Meter is an older, swing arm style, not digital.
The purpose is to re-driver the Cabinet. | Your meter is fine- it's just measuring DC resistance, which isn't quite the same as impedance. Impedance is resistance to alternating current and will vary with frequency. It rises to a peak at the free air resonance frequency and falls off from there, to its minimum, somewhere in the 1KHz- 3KHz range. The DC resistance is lower than the stated impedance, so yes, your driver is 8 Ohm. |
10-13-2011, 02:37 PM
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GBX Member #1 | | Join Date: Jun 2011 Location: London, Ontario, Canada | |  Quote:
Originally Posted by 1958Bassman Look at Parts Express, Antique Electronic Supply, Mojotone, Gerald Weber,..... | I'll take that as a web-wite, and give it a whirl...Thank YOU !!!  |
10-13-2011, 04:58 PM
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Maker of HPF-Pre upright bass preamp | | Join Date: Mar 2004 Location: Madison WI | | Quote:
Originally Posted by patrickbrose Not true. You are only measuring resistance NOT impedance. Using that type of logic, you could just as easily say it is 4ohms.  | The impedance of a mainstream speaker has a large series resistance component equal to the voice coil resistance, that can be measured with an ohmmeter, and is typically around 5 to 6 Ohms for a driver with an 8-Ohm nominal impedance rating. |
10-13-2011, 05:02 PM
| | | I have a random question on impedance, but it is not related to amps. Something I have just been unsure about, but I do not want to ask and steal the spotlight from the original poster, nor create a new thread on something when impedance is already the topic. So I shall ask permission first 
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10-13-2011, 05:18 PM
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John K Custom Basses | | Join Date: Feb 2008 Location: Thousand Oaks, CA | | Quote:
Originally Posted by patrickbrose Not true. You are only measuring resistance NOT impedance. Using that type of logic, you could just as easily say it is 4ohms. | wrong. all 8 ohm drivers have DCR of anywhere from 5.4-7.2 ohms. 4 ohm drivers usually have a DCR of about 3.2ohms. |
10-13-2011, 05:54 PM
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Maker of HPF-Pre upright bass preamp | | Join Date: Mar 2004 Location: Madison WI | | Quote:
Originally Posted by Papa Dangerous I have a random question on impedance, but it is not related to amps. Something I have just been unsure about, but I do not want to ask and steal the spotlight from the original poster, nor create a new thread on something when impedance is already the topic. So I shall ask permission first | I think the OP has an answer, so whale away. |
10-13-2011, 06:27 PM
| | Registered User | | Join Date: May 2006 Location: austin,tx | | Quote:
Originally Posted by fdeck I think the OP has an answer, so whale away. | Wail?....Whale?
Sorry, I do have better things to do right now...I'm just not doing them.
Is there some historical reference where "whale" is correct?
Whale - a mammal that lives in the ocean.
Wail - as in wailing on someone with your fists...or other body parts with the intent of doing damage. Also loud, howling, non-musical sounds produced by the voice or other musical instrument used in a non-musical way....such as "wailing away" on a guitar.  |
10-13-2011, 06:28 PM
| | Registered User | | Join Date: May 2006 Location: austin,tx | | | Also a person from eastern Kentucky or West Virginia trying to pronounce the word "will". |
10-13-2011, 06:34 PM
|  | Endorsing Artist: Wild Turkey Bourbon | | Join Date: Jul 2008 Location: The Wilds of NW Pa. | | Quote:
Originally Posted by will33 Also a person from eastern Kentucky or West Virginia trying to pronounce the word "will". | Nah ... "well".
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10-13-2011, 06:50 PM
| | Registered User | | Join Date: May 2006 Location: austin,tx | | Quote:
Originally Posted by Steveaux Nah ... "well". | My singers name is Bill, he's from Kentucky, his wife is from eastern Kentucky, according to her, especially after a couple, his name has 2 syllables. |
10-13-2011, 07:05 PM
| | | | Okay cool xD I a pretty sure this is related to impedance. It is what someone else referenced to it as, so I kinda just piggy backed it.
On some keyboards, they have 3.5 mm output for headphone. It does not have a 1/4 inch for adding an amp or monitor. One can easily use a converter to fix the connection issue, but I was told there could be an issue with impedance because the output is for headphones, and not an amp. Was I mislead, or is there really something about this? If there is something, what is the issue at hand?
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10-13-2011, 07:20 PM
| | Registered User | | Join Date: May 2006 Location: austin,tx | | Quote:
Originally Posted by Papa Dangerous Okay cool xD I a pretty sure this is related to impedance. It is what someone else referenced to it as, so I kinda just piggy backed it.
On some keyboards, they have 3.5 mm output for headphone. It does not have a 1/4 inch for adding an amp or monitor. One can easily use a converter to fix the connection issue, but I was told there could be an issue with impedance because the output is for headphones, and not an amp. Was I mislead, or is there really something about this? If there is something, what is the issue at hand? | Yes, that has to do with the oitput and input impedances of different electrical devices, not the same as speaker impedance but impedance nonetheless.
The real techs here could give you a more detailed explanation.....the laymen's answer is, you can plug this into that if you keep the gains down.....or turn 'em up if it sounds weak. |
10-13-2011, 07:30 PM
| | Registered User | | Join Date: May 2006 Location: austin,tx | | I used to have this keys player who for some wierd reason thought other musicians didn't like keys and always buried them in the mix so whenever we set levels, he always had the volume on his keyboard at about 1/2, thinking he could turn up later and be heard.
Well, it's easy to bury other instruments with loud keys so after discovering this, I always set his levels low and after he turned up, it was a good mix. Later on, he discovered my trickery and along with it, the fact that I love a good piano/organ player and our outwitting each other became much less and were much more cooperative although there was always a little bit of it but guess what....my fingers were on the mixing board so I get to play God and there's no amount of turning up I can't turn down.
Moral of the story? Get a good keys player who's a team player who keeps their damn left hand out of the lower registers, then turn them up for everyone to hear and all is right with the world. |
10-13-2011, 07:32 PM
| | | Quote:
Originally Posted by Papa Dangerous ...
On some keyboards, they have 3.5 mm output for headphone. It does not have a 1/4 inch for adding an amp or monitor. One can easily use a converter to fix the connection issue, but I was told there could be an issue with impedance because the output is for headphones, and not an amp. Was I mislead, or is there really something about this? If there is something, what is the issue at hand? | It's not a problem to use a headphone out to feed an amp or even a PA or recording console. Headphones are of course, little speakers, their impedance can be any where from 8 ohms to over 32 ohms. The impedance mismatch isn't an issue because 1) it's probably a solid state amp and 2) the power is very low. Just make sure you turn the volume down and bring it up gradually. It's possible the the headphone signal will be too hot and distort the input stages, so listen for that.
But I've used headphone outs as "line outs" on several different keyboards and drum machine, so I know it works fine.
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