To connect home speakers in guitar amplifier - AVS Forum
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post #1 of 15 Old 12-08-2013, 07:57 PM - Thread Starter
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Hi everyone! First post here.

 

I searched a bit on google and youtube, maybe my keywords were off, but I didn't find anything clearly answering my questions.

 

I play guitar in 2 bands : rock and folk. I have a Dual Rectifier with a 4x12 cabinet. It serves me well when I play rock music with my electric guitar, and suprisingly the amp sounds pretty good too when I play my acoustic guitar on the clean channel. But it's a bit overkill to go to an acoustic gig with my half stack amp!

 

I have 2 speakers that I did not hook to my home theater system (Lancaster RX10). Those speakers match my guitar amplifier's impedence (8 ohms) and the max power handling is 100 Watts. The guitar amp is also 100W. The frequency response of the speaker is 70 Hz- 20 kHz.

 

So basically I would like to know :

 

1- Could it work?

 

2- Does it even makes sense? I mean, would it sound good with the given frequency response?

 

3- How would I do that? Do I just take a standard 1/4 jack speaker cable, cut it in half, take the 2 wires out and plug them in the speaker?

 

Thanks a lot!

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post #2 of 15 Old 12-08-2013, 08:12 PM
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Quote:
Originally Posted by niklai View Post

1- Could it work?

Maybe.
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Originally Posted by niklai View Post

2- Does it even makes sense? I mean, would it sound good with the given frequency response?

Guitar speakers are colored by design, HT or hifi speakers are intended to be flat, so they will not be a direct replacement for a guitar cab.
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3- How would I do that? Do I just take a standard 1/4 jack speaker cable, cut it in half, take the 2 wires out and plug them in the speaker?

No. That would result in a 4ohm load. You could rig some sort of series wiring dongle, which would show a 16ohm load. This would result in less volume, the amp working harder, but guitar amps are much more likely to be damaged from "flyback" than getting overloaded.
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post #3 of 15 Old 12-08-2013, 08:22 PM - Thread Starter
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No. That would result in a 4ohm load. You could rig some sort of series wiring dongle, which would show a 16ohm load. This would result in less volume, the amp working harder, but guitar amps are much more likely to be damaged from "flyback" than getting overloaded.

 

The guitar amp has two 4ohm outputs, what if I plug the 2 speakers there?

 

I as well doubt that the sound would be as good as a guitar cab, but I would like to give it a try and see what I can get by playing with the EQs.

 

Thanks for your help, I don't have much knowledge on speaker wiring..!

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post #4 of 15 Old 12-09-2013, 04:11 AM
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Dig out the manual, often, guitar amps will have simply split the output in parallel to create "lower" impedance outputs. Amps with an impedance switch actually utilize different taps on the output transformer to create genuinely different impedance capabilities.
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post #5 of 15 Old 12-09-2013, 04:14 AM
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Actually, the easiest way out would be to use one speaker. You're not getting stereo in any event. Just keep the master down to avoid nuking the speaker, guitar amps and HT equipment are not rated by the same yardsticks.
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post #6 of 15 Old 12-09-2013, 05:31 AM
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Does it even makes sense? I mean, would it sound good with the given frequency response?
No. Guitar speakers and home speakers are totally different in every respect. Get a 1x10 or 1x12 cab or combo for small gigs. You'd probably find a 1x12 plenty for larger gigs as well. The 4x12 is an anachronism of the 1960s, and could serve as a poster child for how not to build a speaker cabinet. They made some sense when 30 watt drivers were as large as there were and there was no such thing as good PA, but that situation ended by 1975.

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post #7 of 15 Old 12-09-2013, 07:10 AM
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It would only cost him a RCA connector and some soldering to find out how it sounds. He's already using a high gain amp with a piezo pickup, so he's clearly OK with a non - traditional sound. Not something I would do, but it shouldn't break anything.

If we send him shopping, I'd suggest an active PA box. Guitar Center had one for black friday for $100.
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post #8 of 15 Old 12-09-2013, 07:17 AM
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It could very well break something and might well break the speaker voice coils. Home audio speakers aren't made to handle the abuse of dealing with guitar pickups and all the signal processing. Take note of Bill's comments above. He is a designer of pro sound speakers as well as home theater speakers.
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post #9 of 15 Old 12-09-2013, 09:13 AM
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I am aware of who he is, and I respect that. I've played guitar for 24 years or so, I've plugged right into receivers, I've played bass through guitar amps, guitar through bass amps, run vocals through instrument amps. Stuff happens, you improvise. The only conditions I am aware of that will break things are impedance mismatches or overloading, neither of which are in play here. I don't know what about pickups and signal processing comprise "abuse," but I'd be glad to learn.

I note Mr Fitzmaurice's comments address the sonic implications exclusively, unless I misread him. Similarly, if one has limited goals regarding the tone produced, I advised to keep the master volume down to avoid any mysterious spikes, and barring any unknowns, nothing will break.

To reiterate, the best thing to do is to grab a powered PA speaker.
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post #10 of 15 Old 12-09-2013, 09:56 AM
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Quote:
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The only conditions I am aware of that will break things are impedance mismatches or overloading, .
In this case the risk of driver damage is severe. Since the average home speaker has at least 10dB lower sensitivity than the average guitar speaker it's quite common for guitar players who try this experiment to be rewarded with magic smoke when they apply enough power to get adequate volume. eek.gif

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post #11 of 15 Old 12-09-2013, 11:52 AM
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Makes sense. I know guitar amps are way under - rated compared to AV gear, that's why I've emphasized taking it easy on the master. How do they they work out the sensitivity numbers, the advertised specs aren't all that different?
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post #12 of 15 Old 12-09-2013, 12:04 PM
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How do they they work out the sensitivity numbers, the advertised specs aren't all that different?
When they aren't it's because the hi-fi manufacturer is lying. mad.gif
The average 1m/1w sensitivity of a hi-fi woofer is 86dB. Some might get to 88dB, some only 84dB. A pair parallel wired will get 6dB higher voltage sensitivity, but that's two watts, not one. A pair will on average have a 1m/1w sensitivity of 89dB. If you see claims of 96dB they're BS, pure and simple, unless the speakers are loaded with pro-sound drivers. They have higher sensitivity because they don't go as low, and run on average 93-95dB 1m/1w. Guitar drivers have even less low frequency extension than pro-sound woofers, so they run around 98dB. Some run as high as 103dB, but those do so by being both very expensive and by chopping off response around 200Hz.

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post #13 of 15 Old 12-09-2013, 12:19 PM
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Ah. For some reason, I remembered guitar speakers advertised in the low 90s, rather than high 90s.
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post #14 of 15 Old 12-10-2013, 12:30 PM - Thread Starter
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Thank you both for helping me out. Well obviously it doesn't seem to be a good idea after all...

 

Bill, when you talk about magic smoke, it's coming from the amp or from the speaker? I don't really mind to blow the speakers off, because I got them for free. But my guitar amp... if I see smoke coming out of it I'll get a heart attack!

 

Since I don't want to pay for a quality acoustic amp, I guess my only options are to buy a PA speaker and plug my guitar straight into it or to buy a small cab and use it with my Mesa amp.

 

As a side note, it's not that I don't care about tone. When I'm recording, I'm using a condenser mic, no pickup at all. But I'm trying to find an affortable solution to play live, and miking is not an option. Since I already have an amp for my electric guitar, I thought maybe I could use it also for my acoustic, with home speakers I already have. I guess it was a little bit naive to think so...

 

I appreciate the help.

 

Cheers!

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post #15 of 15 Old 12-10-2013, 01:40 PM
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The speaker would blow first. If the coil shorts, the amp wouldn't be far behind it.
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