| Series III lead Speakers [message #16244] |
Thu, 13 October 2011 10:29  |
Shakes
Messages: 8
Registered: October 2011
Location: Illinois
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Junior Member |
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Hello, I am a first time user. This forum has been great so far. Kudos to moderators. I just bought a Series III lead SC guitar combo. The speakers are wired up in series and plugged into the speaker-out on the back of the head. Only one of the speakers works, nothing and I mean nothing is coming out of the other one. I know nothing about this stuff but I want to replace the speakers. I have found from this forum that the speakers I get should be 4 ohms each (correct if wrong, please). Is there anything else I should know before purchasing speakers? Should they be plugged into the speaker out through a quarter inch like it is now? What were the speakers like that were originally in this cabinet?
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| Re: Series III lead Speakers [message #16245 is a reply to message #16244] |
Thu, 13 October 2011 12:06  |
chicagobill
Messages: 2005
Registered: April 2003
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Senior Member |
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Welcome to the place.
If your speakers are wired in series, then the dead speaker has to have a shorted voice coil, otherwise the working speaker would not be making any sound either. Do you have access to an ohmmeter? If you do, you can read the resistances of the two voice coils and see what is going on.
Normally, the speakers do plug into the jack on the back panel.
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| Re: Series III lead Speakers [message #16250 is a reply to message #16244] |
Thu, 13 October 2011 17:52 |
chicagobill
Messages: 2005
Registered: April 2003
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Senior Member |
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If you get an ohmmeter, you will want to test the wires that connect the two speakers, as well as each speakers voice coil.
Set your meter to read low ohms and touch the two leads together. You will get some sort of reading. Unless the meter has a zero function, the read out might be something like 0.6 ohms. This reading is how much resistance your two lead wires have. Now separate the two leads and the readout will go back to infinite ohms. This reading could be OL as in overload or it may be blank (no digits). You just need to know what the readout for your meter is.
Now pull out the plug from the head and read the resistance across the two terminals of the plug. This is the resistance that the head is seeing. The reading that you get could be anywhere from 4-16 ohms.
Now follow the wire from the plug to the speakers. If the speakers are wired in series one wire will go the left speaker and the other wire will go to the right speaker. Then there should be a wire that connects the second terminal of the left speaker to the second terminal of the right speaker.
If the speakers are wired in parallel, the two wires from the plug will go to one of the speakers. Then there will be two wires that connect the two terminals of this speaker to the two terminals of the second speaker.
If the speakers are in series, read the resistance across the terminals of each speaker. If they are in parallel, you will have to open the connection between the two speakers before you read the resistance across the terminals.
The dead speaker will read as a short (zero ohms) or wide open (infinite ohms). If you do get a reading across the terminals, then you need to look for a bad connection or wire.
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| Re: Series III lead Speakers [message #16254 is a reply to message #16244] |
Sat, 15 October 2011 11:33 |
Shakes
Messages: 8
Registered: October 2011
Location: Illinois
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Junior Member |
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Can't say enough about how you guys are awesome. So I bought a gauge and followed the instructions. First off, the speakers are wired in parallel (I was wrong about being in series). Now to the ohms. The speaker on the left,the one that works and the one that is not connected directly to the amp, reads around ~5 ohms. I have an analog meter so this could have been 4. The right speaker, the one not working, of a clearly different make than the other, and the one connected directly to the head, also read ~5 at the terminals. When I measured ohms at the quarter inch jack that plugs into the head, it looked like ~8. I believe that this is impossible with parallel wiring, in that your total ohmmage is less. I also can't measure the dead speaker when it's "open", if I'm understanding that correctly, because the working speaker's wires are soddered to the terminals of the dead speaker.
Given this mess, I'm going to probably replace the speakers.
---What's a good match for this head, technically speaking?
---I guess I would need two speakers, 8 ohms each, wired in parallel showing the head a total of 4 ohms. Is that right?
---What sort of wattage do I need? If the head is 130, would I want two speakers of about 50 each?
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| Re: Series III lead Speakers [message #16255 is a reply to message #16250] |
Sat, 15 October 2011 11:34 |
Shakes
Messages: 8
Registered: October 2011
Location: Illinois
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Junior Member |
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Can't say enough about how you guys are awesome. So I bought a gauge and followed the instructions. First off, the speakers are wired in parallel (I was wrong about being in series). Now to the ohms. The speaker on the left,the one that works and the one that is not connected directly to the amp, reads around ~5 ohms. I have an analog meter so this could have been 4. The right speaker, the one not working, of a clearly different make than the other, and the one connected directly to the head, also read ~5 at the terminals. When I measured ohms at the quarter inch jack that plugs into the head, it looked like ~8. I believe that this is impossible with parallel wiring, in that your total ohmmage is less. I also can't measure the dead speaker when it's "open", if I'm understanding that correctly, because the working speaker's wires are soddered to the terminals of the dead speaker.
Given this mess, I'm going to probably replace the speakers.
---What's a good match for this head, technically speaking?
---I guess I would need two speakers, 8 ohms each, wired in parallel showing the head a total of 4 ohms. Is that right?
---What sort of wattage do I need? If the head is 130, would I want two speakers of about 50 each?
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| Re: Series III lead Speakers [message #16270 is a reply to message #16244] |
Mon, 17 October 2011 12:06 |
chicagobill
Messages: 2005
Registered: April 2003
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Senior Member |
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The reading that you got was probably correct for a single 8 ohm speaker. When you measure the resistance, it will always be a little lower than the rated impedance, so an 8 ohm speaker will usually read somewhere around 6 ohms on a meter.
I usually use lamp cord to wire up speaker cabs. It is 18 gauge and can be found at any hardware store or home center. If you want separate wires, just get some 18 gauge stranded wire.
Pleat is right about lower wattage speakers, they tend to sound warmer and are usually more efficient too. The theory would be for a 130 watt amp you would need each speaker to handle 65 watts.
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| Re: Series III lead Speakers [message #16279 is a reply to message #16244] |
Tue, 18 October 2011 11:57 |
chicagobill
Messages: 2005
Registered: April 2003
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Senior Member |
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Are you talking about a shielded guitar cord?
Don't use that as the center conductor is usually too small to handle the power of the amp output. Heavier 14g wire is okay,but as you stated it is overkill, especially with the short lengths of wire that you will be using. Crimp on spade connectors are fine, just be sure that the connections are good and tight.
The one thing that you need to watch out for as Pleat mentioned earlier, is the speaker phasing. Make sure that the two positive terminals on the speakers are connected to each other and that the two negative terminals are connected to each other. If you wire them out of phase, you will lose bass response from the amp.
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| Re: Series III lead Speakers [message #16283 is a reply to message #16282] |
Tue, 18 October 2011 20:26 |
pleat
Messages: 1453
Registered: June 2004
Location: Belding, Mi
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Senior Member |
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If the amp sounded OK with the one good speaker, and your using the same speaker cable from the amp, you may have purchased a pair of bad speakers. If the one good speaker that you got with the amp is louder than the pair you just bought, then you might want to unhook one of the V30 speakers. If there is no change, unhook that speaker and hook up the other one, if the sound is the same than I'd say you have bad speakers. One other thing to check is make sure both speakers are in phase. + to + and - to -.
If they are reversed and out of phase, you will have a very thin sounding amp, low bass response and in general a poor sound.
pleat
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