#1
I have a little blackheart killer ant head which has outputs for 4, 8, and 16 ohms.
I have a 10" cab with an 8 ohm speaker which has a jack to run another cabinet.

I built a custom box for a vintage jensen 12" which reads 6.5 ohms on my meter.

First question: when running just the 6.5 ohm speaker should I use the 4 ohm or the 8 ohm output?

Second: If I connect the 6.5 ohm 12" to the 8 ohm 10" cab and run them both what ohm output should I use?

thanks for any help.
Joe
#2
always use the higher impedance so the 6.5 ohm speaker would round up to the 8 ohm output. As far as both speakers if they are connected in series (which i'm assuming they are) the the impedance like resistance is added so you would use the 16 ohm output.

I am no expert on this matter and would suggest hearing from other people also but this should work.
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#3
Quote by riffmasterjosh
always use the higher impedance so the 6.5 ohm speaker would round up to the 8 ohm output. As far as both speakers if they are connected in series (which i'm assuming they are) the the impedance like resistance is added so you would use the 16 ohm output.

I am no expert on this matter and would suggest hearing from other people also but this should work.



Thankyou, That is what I thought but just want to make sure, I have had the 12" cab into the 8 ohm out for about 15 minutes, I found an old Jensen P12Q dated 1958 in an old hammond cabinet.. After a short listen it sounds better than the weber 10A125 I have in the other cab.
#4
PM Phil Starr, a cabinet designer.

Shooting from the hip:
1. Run the 6.5 ohm cab at 4 ohms from the amp.
2. Since the 2 cabs will present a 3.586 ohms load, setting the amp at 4 ohms might stress the amp and the volume will be lower.

#5
Quote by Ippon
PM Phil Starr, a cabinet designer.

Shooting from the hip:
1. Run the 6.5 ohm cab at 4 ohms from the amp.
2. Since the 2 cabs will present a 3.586 ohms load, setting the amp at 4 ohms might stress the amp and the volume will be lower.


I'm pretty sure you should only run a cab from an output of equal or higher impedance, otherwise you can damage the amp. Higher impedance will lower the volume a bit, but its safe.
#6
Quote by littlephil
I'm pretty sure you should only run a cab from an output of equal or higher impedance, otherwise you can damage the amp. Higher impedance will lower the volume a bit, but its safe.
If you set the amp at 8 ohm going to a 6.5 ohm cab, wouldn't that throw too much power and potentially blow the speakers?

*paging Phil Starr*

#7
1 - Solid state amps are perfectly happy with speakers of the correct impedance or if the speakers are a higher impedance. Most power is transferred when the speaker is of the correct impedance, but no damage will occur if the speaker impedance is higher than the amp is rated for. In fact, you won't damage a solid state amp if no speaker is connected. Do not run a solid state amp with a speaker system that is lower than the amp requires.

2 - Tube amps are a little more particular. Best if they are only used with a speaker system of matching impedance. If the speaker system doesn't match, the safer mismatch is when the speaker is a lower impedance than the amp. It is likely to cause severe damage to a tube amp if no speaker is connected.

3 - It's unlikely that Jensen is a 6.5 ohm speaker. It's very common for a speaker to have a lower DC resistance than its actual impedance. My money says that's an 8 ohm speaker.

4 - Easiest connection for separate speaker cabinets is parallel. I'd put both of those 8 ohm cabs in parallel and connect to the 4 ohm output.
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#8
Quote by SomeoneYouKnew
1 - Solid state amps are perfectly happy with speakers of the correct impedance or if the speakers are a higher impedance. Most power is transferred when the speaker is of the correct impedance, but no damage will occur if the speaker impedance is higher than the amp is rated for. In fact, you won't damage a solid state amp if no speaker is connected. Do not run a solid state amp with a speaker system that is lower than the amp requires.

2 - Tube amps are a little more particular. Best if they are only used with a speaker system of matching impedance. If the speaker system doesn't match, the safer mismatch is when the speaker is a lower impedance than the amp. It is likely to cause severe damage to a tube amp if no speaker is connected.

3 - It's unlikely that Jensen is a 6.5 ohm speaker. It's very common for a speaker to have a lower DC resistance than its actual impedance. My money says that's an 8 ohm speaker.

4 - Easiest connection for separate speaker cabinets is parallel. I'd put both of those 8 ohm cabs in parallel and connect to the 4 ohm output.



thanks for your help.
I guess I am new to series and parallel,
I have a blackheart 1 X 10 cab that is wired in parallel, I installed a weber 8 ohm speaker.
I was told by someone else to use 16 ohms when connecting both the weber and jensen, I think You sound like you know what you are talking about so I guess 4 ohms it is.
#9
The ohms quoted for a speaker are the impedance not the measured dc resistance. This is the resistance of the coil plus a frequency dependant component due to the inductance of the coil. This means that the actual impedance seen by the amp varies between 8ohms and perhaps a hundred ohms depending upon the speakers detailed design.

Both your speakers are 8ohms, try measuring the other one with your meter I'm sure it will also measure 6 ohms or thereabouts.