[Hey_Its_Cole]

I have a real nice guitar tube amp $1000+, It is a mesa boogie nomad, would I be wasting my time attempting to use it as a headphone amp? I figure there is that small chance that it would be great so why not ask.

 

[pearljam]

Interesting question. But it will probably not work and here's why:

My brother is a professional musician and so obviously I have had a lot of experience with guitar amps over the years. A guitar amp is designed to provide a "Sound" which it generally does by introducing some form of distortion. So even though guitar amps sound cool (with a guitar hooked up to them) and have a definite tube sound, they will have a degree of distortion that would be unacceptable for headphone use and full range music reproduction.

The controls on a guitar amp allow a wide range of settings, typically manipulating the gain, compression and other deliberate distortions. Obtaining a good tone and sound for the player generally involves overdriving the output stage which means noise and distortion...a good thing for creating a distict sound for the musician but a bad thing for listening to full range music.

In my experience, even when set to a "clean" setting a guitar amp would produce a large amount of noise for headphone music purposes.

Now if you want to plug in your cans to my brother's guitar amp and have him rock your world by pplaying his Les Paul or Telly, that is a different story!

 

[rickcr42]

Quote:

I have a real nice guitar tube amp $1000+, It is a mesa boogie nomad, would I be wasting my time attempting to use it as a headphone amp? I figure there is that small chance that it would be great so why not ask.

Not applicable without extensive modification.It can be done but in the end not a good way to go unless just as a cool project.Reasons ?

1-way too much gain for one.Guitar preamp stages use two cascaded high gain stages one into the other so you can set the "overdrive" state of the amp second stage.That is the reason you have multiuple adjustment for volume.One is Gain/Drive into the next stage and sets harmonics the other at the very last stage in the amp,just before the power amp output stage and sets overall volume.
The reason it is set up this way is so you can have extreme drive levels even at low actual listening levels.

2-likely there will be two and possibly three or four more stages between this and the actual output (Tone/reverb/etc) and each with its own active device (tube or ss stage) each of which will add noise to the signal.This noise is part of the guitar amp sound and a non issue when used as intended but strap on a set of headphones and plug into a multiple high gain stage headphone output and you will not like the results usually.
Low gain is the domain of the headphone amp,high gain the guitar amp.

3-where will you be taking the signal from ? The first stage after the guitar intput ? Second stage drive ? After the tone controls or other FX ? After the power amp stage ?

Great guitar amps do not neccessarily make for great headphone amps because the overall requirements for each are different so are designed with "end use" in mind but you CAN force it to be what you need if your needs are not high fidelity music but guitasr palyback over headphones.In that case take the "line out" feed used for recording straight out to your cans and listen.Be aware this will be a "mono" output in most cases so you will need a "mono-to-stereo phone jack" adapter or if a stereo output a "Dual TS to TRS Adapter" (two mono phone jacks to a single stereo phone jack).If drive is too low hand a buffer off the output and try that.If volume is not enough (though no way i see that event !) add a gain stage.

hope this helps

rickmongo

 

[Hey_Its_Cole]

Quote:

Originally Posted by rickcr42 Not applicable without extensive modification.It can be done but in the end not a good way to go unless just as a cool project.Reasons ? 1-way too much gain for one.Guitar preamp stages use two cascaded high gain stages one into the other so you can set the "overdrive" state of the amp second stage.That is the reason you have multiuple adjustment for volume.One is Gain/Drive into the next stage and sets harmonics the other at the very last stage in the amp,just before the power amp output stage and sets overall volume. The reason it is set up this way is so you can have extreme drive levels even at low actual listening levels. 2-likely there will be two and possibly three or four more stages between this and the actual output (Tone/reverb/etc) and each with its own active device (tube or ss stage) each of which will add noise to the signal.This noise is part of the guitar amp sound and a non issue when used as intended but strap on a set of headphones and plug into a multiple high gain stage headphone output and you will not like the results usually. Low gain is the domain of the headphone amp,high gain the guitar amp. 3-where will you be taking the signal from ? The first stage after the guitar intput ? Second stage drive ? After the tone controls or other FX ? After the power amp stage ? Great guitar amps do not neccessarily make for great headphone amps because the overall requirements for each are different so are designed with "end use" in mind but you CAN force it to be what you need if your needs are not high fidelity music but guitasr palyback over headphones.In that case take the "line out" feed used for recording straight out to your cans and listen.Be aware this will be a "mono" output in most cases so you will need a "mono-to-stereo phone jack" adapter or if a stereo output a "Dual TS to TRS Adapter" (two mono phone jacks to a single stereo phone jack).If drive is too low hand a buffer off the output and try that.If volume is not enough (though no way i see that event !) add a gain stage. hope this helps rickmongo

This is what I figured but i had it sitting there so why not ask.

 

[kramer5150]

You'll fry power tubes with the impedence mis-match.... or at the very least shorten tube life.
Similar to unplugging your cab, cranking it up and playing.

Tubes dont like not having an optimal imedence load connected to the output stage.

at least this is my understanding... someone please correct me

IMHO youre better off getting a cab simulator for headphone practice... Line6, sans amp... or the likes. Morley JD-10 is my favorite, although it lacks all the delay and modulation effects of my line6.

 

[mkmelt]

The sound signature of a tube guitar amplifier aside, you need a two-channel amplifier (stereo) for headphone listening. A single guitar amplifier will not provide the two separate amplifier channels necessary for stereo listening.

 

[rickcr42]

Quote:

You'll fry power tubes with the impedence mis-match.... or at the very least shorten tube life.

Not at all.headphones are a load just like any other and it will either work or not within the driver/driven match or mismatch

Quote:

Tubes dont like not having an optimal imedence load connected to the output stage.

the stage is already under a proper load because it is working.any additional load will be in parallel so with reduce the resistive load by half but a simp,e resistor can restore all original operating ponts even with cans in place.If this is the actual amp output nothing is need since the tubes are already isolated by a transfomer though there neesds to be a load on the output at all times and maye a simple gain reduction resistor so the volume control can have a usable range.

Any "line out" or "record out" could be used potentially for headphones but this is better served if the actual interface is a headphone amp following the output.

Still,not the best soltion if noise levels are important unless the amp is designed for the recording studio environment.

Quote:

A single guitar amplifier will not provide the two separate amplifier channels necessary for stereo listening

simple "Y" adapter as stated above

 

[cpw]

Aside from the stereo/mono issue, the requirements of driving a 12" speaker to stage levels vs a small headphone driver 1" from the ear are sooo different that it realy isn't worth the effort.
I have a Boogie too (MKIII combo, I've also had a MKIV as well as others)
CPW

 

[rickcr42]

Quote:

Aside from the stereo/mono issue, the requirements of driving a 12" speaker to stage levels vs a small headphone driver 1" from the ear are sooo different that it realy isn't worth the effort.

Actually that depends on the headphones CPW.Certain AKGs for instance need an actual power amplifier/resistor matrix to get the proper amount of power because they were designed to be driven directly from the studio control amplifer.Use a whimpy opamp headphone amp and the results will be not good.
It is also tru that low power pentode amps make nice headphone amps with a resistor matrix to match/limit the output but only if noise levels are low.
I have a 20WPC Class-A amp that has my ASL UHC matching transformer and Stax Transformer interface on the output (no speakers at all !

) through a speaker selector box and it sounds damn nice though with Grados just a bit too "literal" for my taste so having headphones hooked up to a p[ower amp stage alone not a bd thing if that stage is quiet enough and has enough.
Where a guitar amp has limitations is in the noise department unless specifically designed to be quiet like with a studio guitar amp but a stage amp usually not.there is also the built in bandwidth limitations for instrument use that make the amp suitable only for the instrument it ewas designed for and by no meanms ready for a full bandwdth hi-fi signal.