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Topic: ?? Plug small amp output into bigger powerful amp ?? |
Eddie Cunningham
From:
Massachusetts, USA
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Posted 4 Apr 2014 12:41 pm |
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| Is it possible to plug the speaker output of a small , nice sounding amp ,like a battery powered or even an A.C. powered small amp into a bigger , more powerful amp to get the nice "small amp" sound more amplified ?? I need the "experts" opinion before I blow something up !! Thanks !! olde geeze - AKA Eddie "C" |
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Lane Gray
From:
Topeka, KS
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Posted 4 Apr 2014 12:53 pm
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Only if the small amp has a headphone out. Headphones are REALLY close to line-level devices, and an amp can usually accept line level at the instrument input.
I strongly suspect that if an input saw power levels meant to drive even a 6" speaker it'd fry something.
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Erv Niehaus
From:
Litchfield, MN, USA
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Posted 4 Apr 2014 12:54 pm
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DON'T!!!
The signal from one amp is much too hot to feed into the input on another amp. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 5 Apr 2014 6:12 am
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Amps used to come with this feature... my '61 Gibson has it. Amps without negative feedback can do this because the speaker output is fully transformer isolated... you'll need to determine if this is the case. Battery-powered amps are definitely OK with this.
The theory is, you use a reduced voltage by using a 'resistor-divider'. Put two resistors in series across (in parallel) with the speaker, then take your other amp's input from across one of these resistors. Typically one resistor is much larger than the other and you take your output from across the smaller resistor.
You get the same effect by using a potentiometer... put a 10K pot's outside terminals across the speaker terminals and take your output from the wiper to one of the terminals. Keep the wiper close to this terminal for small output voltages (start with zero!).
If your amp doesn't have an isolated speaker output then you'll want to transformer-isolate the signal you get before you try to connect it to another amp or you'll get hum (from the ground loop). Mic transformers can be used for this, put your divided signal into pins 2&3 of the XLR side and plug the 1/4" transformer into the larger amp.
Easiest for this... there are DI boxes made to do this. It will say 'speaker level' and it will have 'ground lift' capability as well as a 20dB or so 'pad'. The 'pad' is the resistor divider we made, above. The box goes between the amp and speaker, with the output to the big amp taken from the box.
Tube amps always need to have their design load in place... so either leave the speaker connected or put a load resistor (8ohm 10watt, say) resistor in place of it. Solid-state amps don't normally need a speaker load but there are exceptions.
And if you let the magic smoke out of anything, welcome to the club! You can certainly blow stuff up trying this, so don't attempt any of this unless you understand the theory and practice as I've explained above. Chances are, if you don't already own an ohmmeter and soldering iron, you probably should buy the DI box.
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