Extension cab for Hughes & Kettner combo

[Labi]

I am using a Hughes & Kettner QC310 1x10" 250w combo which is so far the only amp that has met all of my requirements regarding sound, power, size and weight. But from time to time i just need extra power, so I was thinking of getting an extension cabinet. Most probably a single 15". Any suggestions? Thanks!

[Ray man]

Hey there, I have the QC412.

I want to point out that an external speaker's resistance will be added to the internal, because it's a serial connection.
The internal speaker of the QC310 is 8 ohms. So I assume you should look for a 4 ohm perhaps.

The other speaker output bypasses the internal speaker. The manual says you shouldn't used this output with an impedance lower than 8 ohms.


I thought I should point that out.

[Labi]

Originally Posted by Ray man

Hey there, I have the QC412.

I want to point out that an external speaker's resistance will be added to the internal, because it's a serial connection.
The internal speaker of the QC310 is 8 ohms. So I assume you should look for a 4 ohm perhaps.

The other speaker output bypasses the internal speaker. The manual says you shouldn't used this output with an impedance lower than 8 ohms.


I thought I should point that out.

Thanks for your input Ray man. When you say 4 ohms, do you mean that the overall impedance should equal 4 ohms (which can be achieved by adding another 8 ohm speaker) or are you saying that the extension cab should be at 4 ohms?!

Also thank you for the info about the other speaker output the one that bypasses the internal one. I wasn't aware of that.

[Ray man]

Originally Posted by Labi

Thanks for your input Ray man. When you say 4 ohms, do you mean that the overall impedance should equal 4 ohms (which can be achieved by adding another 8 ohm speaker) or are you saying that the extension cab should be at 4 ohms?!

Also thank you for the info about the other speaker output the one that bypasses the internal one. I wasn't aware of that.

I'll try and answer the best I can so hear goes.

If an 8 ohm external cab is connected in parallel to the 8 ohm internal speaker, then it would indeed equal 4 ohms.
But the external speaker is connected in series with the internal speaker. So it's going to add resistance rather that cut it in half.
Therfore, if you get an external cab it's probably better for it to be 4 ohms since it's gonna be added to the total impeadance. You might get away with an 8 ohm extension cab, but that would total 16 ohms.

According to the QC310 manual, the other output (that bypasses the internal) should be no lower than 8 ohms.


Hope it helps. I'll try and aswer more questions if you have.

[Labi]

Originally Posted by Ray man

I'll try and answer the best I can so hear goes.

If an 8 ohm external cab is connected in parallel to the 8 ohm internal speaker, then it would indeed equal 4 ohms.
But the external speaker is connected in series with the internal speaker. So it's going to add resistance rather that cut it in half.
Therfore, if you get an external cab it's probably better for it to be 4 ohms since it's gonna be added to the total impeadance. You might get away with an 8 ohm extension cab, but that would total 16 ohms.

According to the QC310 manual, the other output (that bypasses the internal) should be no lower than 8 ohms.


Hope it helps. I'll try and aswer more questions if you have.

Ray u're the man. Thanks again. All of the amps that I've had so far had their external speaker connection wired in parallel. That's why I was confused. It's now crystal clear.

[Ray man]

Originally Posted by Labi

Ray u're the man. Thanks again. All of the amps that I've had so far had their external speaker connection wired in parallel. That's why I was confused. It's now crystal clear.

Yeah, it's kinda weird that it's in serial. I don't see the logic, oh well.

Glad to help you.
Latter

[Labi]

Originally Posted by Ray man

Yeah, it's kinda weird that it's in serial. I don't see the logic, oh well.

Glad to help you.
Latter

Does this mean that by adding another cab I won't be getting more power? Did you use your QC412 with an extension cab? What's your experience? Did it sound better, louder? Sorry for bombarding you with questions?

[Ray man]

Originally Posted by Labi

Does this mean that by adding another cab I won't be getting more power? Did you use your QC412 with an extension cab? What's your experience? Did it sound better, louder? Sorry for bombarding you with questions?

No problem, I do what I can. First I want to say that if your happy with the amp, then smile and enjoy it for what it is.

Anyway, I dug this out of the manual;

SPEAKER OUT A
"This is a serial speaker out, meaning that external speakers are
connected serially to the internal speaker(s). The external speakers’
resistance is added to the internal speaker or speakers’ resistance of
4 ohms (8 ohms for the QC 310), so you may connect speakers with
low resistance ratings. Although increasing speaker resistance
decreases power amp output, the overall level actually increases
due to the larger speaker surface area (which also reduces power
amp wear)".
In my opinion the sound isn't louder, just different. How different depends on the cab you choose.

I have a few things to say regurding my experience with the QC412. The head itself has a stellar clean sound with beautiful compression (tube growl). To me, the weakness is the 12" speaker and the cab itself.
I usualy bypass the internal speaker and plug into a 2x10 cab. Let me expalain why; I like a faster attack with a leaner more edgy tone. The 12" speaker is too warm and boomy for my requirments.
It's perfect for that rubbery Sgt. Pepper sound.

[Labi]

Originally Posted by Ray man

No problem, I do what I can. First I want to say that if your happy with the amp, then smile and enjoy it for what it is.

Anyway, I dug this out of the manual;

SPEAKER OUT A
"This is a serial speaker out, meaning that external speakers are
connected serially to the internal speaker(s). The external speakers’
resistance is added to the internal speaker or speakers’ resistance of
4 ohms (8 ohms for the QC 310), so you may connect speakers with
low resistance ratings. Although increasing speaker resistance
decreases power amp output, the overall level actually increases
due to the larger speaker surface area (which also reduces power
amp wear)".
In my opinion the sound isn't louder, just different. How different depends on the cab you choose.

I have a few things to say regarding my experience with the QC412. The head itself has a stellar clean sound with beautiful compression (tube growl). To me, the weakness is the 12" speaker and the cab itself.
I usually bypass the internal speaker and plug into a 2x10 cab.

OK let's conclude this.
Another cab doesn't mean extra power, therefore I'll leave it as it is. It just bugs me how the hell does a single 10" handle 250 watts, but hey, if it works I am not going to fix it am I? Thank you for your time and all the useful info.

[Ray man]

I would say another cab might bring out previously hidden frequencys making it sound fuller. But there wont be an increase in power if the resistance is higher.
So I wouldn't be in a rush to get a cab.

I do know that little 12" can take a lot of power. Why? I don't know but it does.

[RickenBoogie]

also, it's doubtful that the single 10 IS handling all that power. I would suspect that if you crank the gain, volume, and low eq, you could seriously damage that little spkr.

[Ray man]

Originally Posted by RickenBoogie

also, it's doubtful that the single 10 IS handling all that power. I would suspect that if you crank the gain, volume, and low eq, you could seriously damage that little spkr.

I know your right, I just can't expain why. I would expect that kind of power would microwave both the ten and twelve.
The funny thing is before I learned how to control my EQ, I used to max every knob on this amp including both pre and post gain.
Never even farted.

All that aside, the 12 in that box resonates an overwhelming upper bass tone resulting in many notes sounding the same.