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Ohms FAQ

#801
B-string said:
G-K cabs are all wired with speakers in parallel. If the Backline 410 was 8 ohms the speakers are 32 ohms each, if it was a 4 ohm cab they are 16 ohms each. Anything else than this and the speakers are not the original speakers for that cab. The GC Acoustic is more than likely using series/parallel wiring with "off the shelf" voice coil windings (8 or 4 ohm impedance). Does the Acoustic cab say 4 ohms on the input plate?
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Okay, so I opened up cab. And they are 32 ohm speakers. I was wrong. So cabinet is 4 speakers at 32 ohm ea. so that makes it a 8 ohm unit correct?

Now can I rewire to make 4 ohm? Or add something so I can SAFLEY use with the 4 ohm output on acoustic cabinet?
 
#802
B-string said:
G-K cabs are all wired with speakers in parallel. If the Backline 410 was 8 ohms the speakers are 32 ohms each, if it was a 4 ohm cab they are 16 ohms each. Anything else than this and the speakers are not the original speakers for that cab. The GC Acoustic is more than likely using series/parallel wiring with "off the shelf" voice coil windings (8 or 4 ohm impedance). Does the Acoustic cab say 4 ohms on the input plate?
Click to expand...
 

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#803
Bottleshok said:
Okay, so I opened up cab. And they are 32 ohm speakers. I was wrong. So cabinet is 4 speakers at 32 ohm ea. so that makes it a 8 ohm unit correct?

Now can I rewire to make 4 ohm? Or add something so I can SAFLEY use with the 4 ohm output on acoustic cabinet?
Click to expand...

No way to make it 4 ohm, but you can already safely use it. The 8 ohm is already above the 4 ohm minimum of the amp. The trouble is you already have a 4 ohm cab (the Acoustic cab) and adding ANY other cab will drop the load below the 4 ohm minimum unless those jacks are series and not parallel. Many of the GC Acoustic combos had series output jacks, I don't know if the head units did the same.

The 8 ohm G-K will work and be perfectly safe for the amp head so try each cab on its own and see which you prefer. If you like the G-K you can add a second 8 ohm cab, if you like the GC Acoustic you are done, no more additional cabs without the danger of burning out the amp.
 
#804
Bottleshok said:
I didn't have a input back plate/jack so I canablized a patch cord and used to for an input cable it is directly connected to the first speaker in the run.
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Welcome to Talkbass.
Is this a shielded instrument cable, with one cable inside then some wire? Or a Speaker cable, two cables inside that are the same size?
In a patch cord the small wire inside is your shielding, it can not take the power of your amp, this will heat up and possibly damage your amp.
You need to use a speaker cable.

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#805
B-string said:
No way to make it 4 ohm, but you can already safely use it. The 8 ohm is already above the 4 ohm minimum of the amp. The trouble is you already have a 4 ohm cab (the Acoustic cab) and adding ANY other cab will drop the load below the 4 ohm minimum unless those jacks are series and not parallel. Many of the GC Acoustic combos had series output jacks, I don't know if the head units did the same.

The 8 ohm G-K will work and be perfectly safe for the amp head so try each cab on its own and see which you prefer. If you like the G-K you can add a second 8 ohm cab, if you like the GC Acoustic you are done, no more additional cabs without the danger of burning out the amp.
Click to expand...
Thanks for the speaker cable info. Here what happened last night,
I plugged in both bass cabinets that are both 8 ohm (8 ohm
 
#806
Bottleshok said:
Thanks for the speaker cable info. Here what happened last night,
I plugged in both bass cabinets that are both 8 ohm (8 ohm as written on plate of acoustic cabinet and by looking at speakers on gk cabinet)
I first put head into protection mode. Them it popped a power strip breaker. After reset I unplugged g-k and all played well for 3 hours. Now I love the sound with both hooked up. The acoustic unot has a lot of high and gk has the low end. Now is the speaker cable thing a big issue ? And maybe be my cause of the effect? And I will make sure the gk is wired in parallel spec but I'm just double checking that the 2 8 ohm cabs are fine with a 4 ohm min. Head
Click to expand...
 
#807
B-string said:
Some of those "Acoustic" amps from GC have series speaker output jacks, if this is the case it may be why the amp didn't go up in smoke with the two cabs. But it was not too far from it so lets get things sorted out before you try again. ;)
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Thank for the help. Okay o got 2 8 ohm cabinets the Krueger is parallel and the acoustic is I don't know yet. I will make sure the Krueger and acoustic cabs have The correct cables ie. Speaker not patch. The head is a 4 ohm minimum. Now what if the acoustic cab is a series wiring job? Do I change to match Kruger.
 
#813
Bottleshok said:
Yes but I'm havin head go in to protect mode do you think its the patch cord I'm using would that do it
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It's unlikely because you don't play any note, right?. If I understand right the amp goes into protect mode immediatelly, so that has nothing to do with a patch (or no patch).
DIY cables?
Check resitance of hot (+) versus ground (-). Your Ohm meter should read infinite number "OL". Although Ohm meter reads a "infinite" number of resitance it's good practice to check solder points for loosely wires.
 
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#814
If you are not using a speaker cable then yes absolutely. Patch cords are low signal level shielded leads that overheat and melt when used as speaker cable. Other option is a wiring fault in the Acoustic cab, it should use 8 ohm speakers wired series/parallel. If the Acoustic cab was "rewired" with all speakers in parallel (to get the most wattage) it will be a 2 ohm cab.
 
#815
ThisBass said:
It's unlikely because you don't play any note, right?. If I understand right the amp goes into protect mode immediatelly, so that has nothing to do with a patch (or no patch).
DIY cables?
Check resitance of hot (+) versus ground (-). Your Ohm meter should read infinite number "OL". Although Ohm meter reads a "infinite" number of resitance it's good practice to check solder points for loosely wires.
Click to expand...
Although meant to fix an issue,
Don't use instrument cables for cabinet/speaker application!
 
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#816
B-string said:
If you are not using a speaker cable then yes absolutely. Patch cords are low signal level shielded leads that overheat and melt when used as speaker cable. Other option is a wiring fault in the Acoustic cab, it should use 8 ohm speakers wired series/parallel. If the Acoustic cab was "rewired" with all speakers in parallel (to get the most wattage) it will be a 2 ohm cab.
Click to expand...

just dropping in to say that you are awesome, b-string! always patient, always helpful. heed this man and his advice!
 
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#819
ThisBass said:
Although meant to fix an issue,
Don't use instrument cables for cabinet/speaker application!
Click to expand...
No not immediately, as I am playing it pops off I turn of and back on and fine. It also popped a power strip while playing as well. The acoustic cab is factory wired perfect. The gk cab was a unit I had to repair before be able to play, the back plate was gone. I took a PATCH cord and uses it as first connection in run ( diced it up) so I'm going to get 2 speaker cables and rewire gk in parallel and get a back plate and make sure back to factory spec. and I should be all set correct?
 

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