Can a regular stereo amp be used for guitar?

[syzygyn]

I have an old Onkyo amp that I was going to give my daughter to power her speaker cabinet. She says it wouldn't work but I don't see why not. Will someone explain to me what makes the usual musician amp different from a regular stereo amp?

[Chuck H]

Guitar amps aren't like reference amps in many ways. Just like a smart car isn't a tractor and vice versa. Both motorized vehicles with four wheels, but not interchangeable beyond those qualities.

[Leo_Gnardo]

The sort of tone quality generally expected for electric guitar isn't generally available through hi fi amps. The Onkyo doubtless will carry signal from guitar thru amp then onto speaker cab but won't sound "right" for guitar. Possible solution - she could use a preamp intended for electric guitar, patch preamp output to the aux input of the Onkyo. But that makes for a system that's a bit more complicated than necessary and inconvenient to set up. Plus only one channel of the Onkyo will be in use.

Onkyo made above-average quality equipment. I've always been satisfied with it. But hi fi gear generally is intended for home use with recorded music. It isn't intended to be used the way you propose. Long, loud playing will overheat the power amp resulting in either destruction of the power amp, or if you're lucky the amp has thermal shut-down devices which will switch it off typically right in the middle of a hot solo. Not acceptable.

Of course there are exceptions... In the early-mid 1970's the Grateful Dead made use of dozens of McIntosh 300 watt per channel industrial strength hi fi amps powering tall columns of JBL speakers. Of course they sounded great, if you like that sort of thing. Guitar signals were passed through Fender Twin Reverb preamps on the way to those power amps, and it took hours to set up & tear down that enormous rig. In the end they decided it wasn't worth the trouble and expense. Best to select a guitar amp, and let that Onkyo survive in style doing its thing powering a pair of nice stereo speakers.

[nosaj]

When I was about 15 or so. I got a guitar but had no amp to hear myself. So I used my dad's Panasonic stereo it had a tape deck with a 1/4 mic input. i would plug in there, open the tape door push the record switch with a pencil then hit the record button and play away through the speakers.

nosaj

[glebert]

I've done it with a thrift store stereo, going into an RCA input, but the output was always weak and a bit flabby. Of course the problem is that I was putting an instrument level signal into a line level input, along with the voicing issues stated above. If it has a mic input like in nosaj's case it may work a little better. I think a $20 pawn shop practice amp will still sound better and be easier.

[nosaj]

I've done it with a thrift store stereo, going into an RCA input, but the output was always weak and a bit flabby. Of course the problem is that I was putting an instrument level signal into a line level input, along with the voicing issues stated above. If it has a mic input like in nosaj's case it may work a little better. I think a $20 pawn shop practice amp will still sound better and be easier.

Probably so but when your poor you use what sitting around. I'm sure there are several here that took old tube radios and converted them to a guitar amp when they were little.

nosaj

[Chuck H]

One could take the Onkyo to the nearest pawn shop and trade or partial trade it for a proper guitar amp.

[mikepukmel]

The sort of tone quality generally expected for electric guitar isn't generally available through hi fi amps. The Onkyo doubtless will carry signal from guitar thru amp then onto speaker cab but won't sound "right" for guitar. Possible solution - she could use a preamp intended for electric guitar, patch preamp output to the aux input of the Onkyo. But that makes for a system that's a bit more complicated than necessary and inconvenient to set up. Plus only one channel of the Onkyo will be in use.

Onkyo made above-average quality equipment. I've always been satisfied with it. But hi fi gear generally is intended for home use with recorded music. It isn't intended to be used the way you propose. Long, loud playing will overheat the power amp resulting in either destruction of the power amp, or if you're lucky the amp has thermal shut-down devices which will switch it off typically right in the middle of a hot solo. Not acceptable.

Of course there are exceptions... In the early-mid 1970's the Grateful Dead made use of dozens of McIntosh 300 watt per channel industrial strength hi fi amps powering tall columns of JBL speakers. Of course they sounded great, if you like that sort of thing. Guitar signals were passed through Fender Twin Reverb preamps on the way to those power amps, and it took hours to set up & tear down that enormous rig. In the end they decided it wasn't worth the trouble and expense. Best to select a guitar amp, and let that Onkyo survive in style doing its thing powering a pair of nice stereo speakers.

Leo, geez, the young lady would probably only need 1/4 that for her first guitar rig.

[mikepukmel]

I have an old Onkyo amp that I was going to give my daughter to power her speaker cabinet. She says it wouldn't work but I don't see why not. Will someone explain to me what makes the usual musician amp different from a regular stereo amp?

Double what Chuck said. Depending on where you live, and how safe you feel doing it, maybe try a "trade for practice guitar amp" think on Craigslist. What's the year and model of you Onkyo amp?

[Leo_Gnardo]

Probably so but when your poor you use what sitting around. I'm sure there are several here that took old tube radios and converted them to a guitar amp when they were little.

nosaj

Who says poor? Folks at any level of $ucce$$ try to save a buck when they can, no problem with that. Over the last 30 years or so it's been a sort of cottage industry, converting old radios, mono & stereo tube hi fi amps, and PA amps into guitar amps. Further back, consider Terry Kath's Knight or Bogen PA head he used with Chicago. Tone for days - even Jimi Hendrix was impressed. Can't argue with that guy's tone, just WOW!

One thing to consider, a rarely mentioned item called "duty cycle." Most hi fi amps are expected to be used with recorded music, set up to - at best - barely go past clipping (100% power) on music peaks. With regular music (Metallica albums the exception) that amounts to about 10% duty cycle. The hi fi amp doesn't overheat, and the music comes out sounding acceptable. OTOH guitar amps are expected to be used blaring loud, 100% duty cycle isn't unusual, and the amp must be designed and built to handle that situation. No wonder tube amps excel in this application, and those who use consumer hi fi amps for rock guitar are disappointed when their prize turns into a smoking box of silicon rubble with no value at the pawn shop or anywhere else.

Chuck's suggestion may be the best, as long as you have no further plans for the Onkyo.

[Leo_Gnardo]

When I was about 15 or so. I got a guitar but had no amp to hear myself. So I used my dad's Panasonic stereo it had a tape deck with a 1/4 mic input. i would plug in there, open the tape door push the record switch with a pencil then hit the record button and play away through the speakers.

nosaj

Proving - you can send a guitar through a hi fi amp. And everything's OK at low volumes, although the tone isn't quite what you wished for. I'll bet every amp you used since then sounded superior to the Panicsonic. FWIW I've done the same. It was far from impressive. What our UK friends say, courses for horses, right? Woops, may have got that back'ards...

[syzygyn]

It's a model 5160 100W stereo amp. It likes ohm speaker values in the 8-16 range which matches her cabinet. I told her all she would need is a phono to RCA pin conversion cable. She has a GSP21 sound modeler and I think that has a input signal adjustment so will she still have a problem with the signal from her guitar? If line level is 2V, what is the typical guitar signal? What about voice from a mic and bass? I could probably get $100 for the amp on Ebay but what kind of music amp would that amount get me? I don't want to trade okay for worse.

[Helmholtz]

Most hifi amps have input impedances around 50k. Most pickups sound best at input impedances of 500k or greater. So it may be a good idea to use a buffer or buffered pedal like e.g. a Tubescreamer in front of the stereo amp. The signal at the pedal's low impedance output can be easily split to drive both channels.

[nosaj]

Who says poor? Folks at any level of $ucce$$ try to save a buck when they can, no problem with that. Over the last 30 years or so it's been a sort of cottage industry, converting old radios, mono & stereo tube hi fi amps, and PA amps into guitar amps. Further back, consider Terry Kath's Knight or Bogen PA head he used with Chicago. Tone for days - even Jimi Hendrix was impressed. Can't argue with that guy's tone, just WOW!

One thing to consider, a rarely mentioned item called "duty cycle." Most hi fi amps are expected to be used with recorded music, set up to - at best - barely go past clipping (100% power) on music peaks. With regular music (Metallica albums the exception) that amounts to about 10% duty cycle. The hi fi amp doesn't overheat, and the music comes out sounding acceptable. OTOH guitar amps are expected to be used blaring loud, 100% duty cycle isn't unusual, and the amp must be designed and built to handle that situation. No wonder tube amps excel in this application, and those who use consumer hi fi amps for rock guitar are disappointed when their prize turns into a smoking box of silicon rubble with no value at the pawn shop or anywhere else.

Chuck's suggestion may be the best, as long as you have no further plans for the Onkyo.

I said poor because that what I was growing up. WE only got new electronics when my dad would go on a WesPac tour, he'd pick stuff up in japan cheaply and send it back home. I remember our first VCR like a big briefcase with a 25ft corded remote.
Most other things we got were always used and he would refurbish them for our family which in turn taught me the same principal, people always get rid of useful stuff if you know where to look.

nosaj

[g1]

My spider sense is tingling a bit on this one, so interested to see how it plays out.