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speaker question

E

elonoic

Guest
May 29, 2013
67
0
Oporto, PT
#1
So, a friend of mine gave me a combo amp that I want to use just as a cab, since I got my own amp.

The thing is, he couldn't tell me anything about the speaker in it.
He said he replaced the speaker not long before he stopped using that combo.

The combo is 90 watts, so I must assume the speaker in there is close to that.

1st question: Is there a way I can know impedance and wattage of that speaker? Only thing left in the sticker in its back is HH Acoustics, so I only know the brand really..

2nd question: About how far could I push the speaker without damaging it, considering my amp pushes 350w@8ohms and 500w@4ohms? Keep in mind I have no idea what's the speaker impedance..


PS: If it helps in anyway, the combo is an old Carlsbro Cobra 90 BG.
 
#3
+1 not the best of ideas. At best, you can measure the DC resistance of the spkr to figure its nominal impedance, but don't for a second assume its power handling by the amps output. It could be anything, but what it's not- is a good solid bass spkr. Just use your new amp with a good bass cab.
 
#4
If you really need the additional cab and money is tight, you could replace the cab's 'replacement' 15 inch driver with an 8 ohm driver having at least 300w (thermal) power handling and with t/s specs that would be compatible with that cab. Online photo shows the cab to be ported at the bottom. If you provide cab, wall thickness and vent dimensions we can provide some useful advice. The driver will likely cost around $100 USD or more.
 
#5
Money is tight, but I can and was going to buy a cab (most likely gk neo 115) but then this friend gave me that to see if I could do something out of it. But if I'm possibly going to damage I kinda prefer to sell it for parts or something and buy the new cab myself.
 
#6
elonoic said:
Money is tight, but I can and was going to buy a cab (most likely gk neo 115) but then this friend gave me that to see if I could do something out of it. But if I'm possibly going to damage I kinda prefer to sell it for parts or something and buy the new cab myself.
Click to expand...

+1 for all this.

If you can swing the money, you are much better off getting the GK Neo 115, than trying to work with the relatively small combo cab.

Good luck!
 
#7
It is really simple. The numbers matter very little. Use your EARS, not a calculator (and this is coming from an electronics engineering student). Just listen for signs of distress. When it starts to SOUND like it is getting too much, then it IS getting too much. Simple as that.

But if you are interested, here's a really simple video showing how to check impedance.


You can Google "how to check speaker impedance" and a gagillion videos and web sites will pop up.
 
#9
Fair enough. The load and frequency (as well as the rest of the circuit) will make a difference. I was just trying to keep it simple. Do you honestly think the OP is at the point of trying to wrap his head around that? Not knocking him, just pointing out his inexperience with electronics.
 
#11
Jensby design said:
:confused::confused:
whats the difference:confused:
Click to expand...

Resistance applies to direct current, impedance, also measured in ohms, applies to alternating current. Resistance is a component of impedance, but impedance also has additional components due to any capacitance or inductance in the circuit (the capacitance and/or inductance in the circuit cause additional impedance, I can't recall the correct names- reactance and ???).

https://en.wikipedia.org/wiki/Electrical_impedance

It was reactance! Yay me!
 
#13
two fingers said:
Fair enough. The load and frequency (as well as the rest of the circuit) will make a difference. I was just trying to keep it simple. Do you honestly think the OP is at the point of trying to wrap his head around that? Not knocking him, just pointing out his inexperience with electronics.
Click to expand...
All the more reason to use correct terminology.
Using a multimeter method to "impedeance", could cause the OP to think he has an oddball 6 ohm or 3 ohm driver.
 

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