Headphone amp / mixer

[bones79]

Hi all,

I'm thinking of building something for late night practice. So far, I'm leaning towards the mxr headphone amp, but it would be nice to have an additional (stereo) input from my phone, so I could play along to tracks.
I think the chain from guitar would be something like:
Drive/delay/reverb > amp sim > headphone amp/mixer

Any ideas or suggestions would be appreciated.

Thanks!

[bones79]

Can't find any vero guides on what I need, so looks like I'll be buying either a Carl Martin Rock Bug (exactly what I'd like to build, plus an xlr out), or a mackie 402vlz4 compact mixer. Anyone used either or have any other recommendations?

Cheers

[Blackboarcult]

Haven't tested those two, but for the same purpose I use a simple audio interface (M-Audio Fast Track Pro) that works also on standalone mode. If you are using a cabsim, there's not really need for anything more than a small 2-track mixer.

Or you could get yourself a Rockman Guitar Ace/X100 if you happen to find one second hand at a reasonable price: guitar in, headphones out, line in and instant 80's AOR tone in 3 settings (clean, crunch and dist). This way you don't even need anything between your guitar and the gadget

The rock bug looks rather nice, though!

[bones79]

Looks like the m-audio box is discontinued, but I'll check their other options, I liked the sound cards they used to make.
Will keep an eye out for a rockman!
Gonna hunt a little longer for schematics/layouts, then buy something if no luck. Leaning towards the CM rock bug, though it's not cheap.
Thanks for the reply!

[Bodge]

http://guitar-fx-layouts.42897.x6.nabble.com/JamMix-Headphones-Practice-Play-Along-Amp-td26681.html
Haven't built it but seems to be what you are looking for

[bones79]

Brilliant, bodge - thank you!

[MAO]

The final combination of the Timmy and modifed JamMix worked out pretty well as a stand alone unit, but I built another version using a modified Runoffgroove Condor which I combined with the modified JamMix which also sounds pretty good as a stand alone unit, both clean and with some gain, but also more useful for stackung with or testing other pedals.

And its really cool to be able to pan your guitar left or right while playing along with music.

http://guitar-fx-layouts.42897.x6.nabble.com/runoffgroove-Condor-with-mods-td42252.html

FWIW, Im thinking of building one more version using a variant of the 27v boost as part of the modified Condor + the modifed Jam Mix. I may also put the clippers on a toggle so I can bypass them completely when feeding this newest version with another dirt pedal.

I just havent gotten to it yet as the current version linked above is working out nicely.

[GrooveChampion]

Wait I dont get it, do cab sims need a headphone amp circuit? Cos I tried plugging my AKG recording headphones into the output of a bass preamp and nothing.

[MAO]

I would say the simple answer is if the cab sim doesn't have a headphone output, then most likely you would need a headphone amp.

As I understand it, in non-technical terms, a simple cab sim will roll off the highs and usually has a notch filter or two to mimic the frequency curve of a particular cabinet/speaker combo.  

To work properly with a pair of headphones, the output signal also needs to be increased a good bit AND the output impedance needs to be low enough to drive a pair of speakers. Cab sims may or may not provide this.  

A high output pedal may be able to drive a pair of headphones on it's own, but most likely will not be very loud, and not sound very good due to the impedance mismatch and all those frequencies passing through.



   

[GrooveChampion]

I guess this is why the 386 is common chip in headphone amps. Sorry for my ignorance, MAO, and thank you so greatly for your patience

[bones79]

Good info, thanks Mao. I already have a timmy built and boxed, so I think I'm going to use a cab/speaker sim with the headphone amp, so I can use various amp sims and drives into it. On the lookout for a good celestion blue/green sim vero now! Alternatively, could use an eq...

[MAO]

That's a great approach bones79.

I did something similar, I built my 1st couple headphone amps in "modules". Highly recommended!  

I used this for the headphone amp section, which has an audio input, and a panning control for the guitar which is great when playing along with audio so you can place the guitar anywhere in the stereo mix.  (see the 03/19/2016 post for the stripped down headphone amp section)

Then I tried multiple distortions, overdrives, eqs and cab sims as the front end.

As with everything, there are positives and negatives with each.

The best option/combination really depends on what your main goal is...and your gear. Taking a modular approach until you dial it in will be the most efficient way to do it.

One suggestion I would make is if/when possible use a charge pump for at least the input and headphone amp sections to get the most headroom. The headphone amp section I linked to uses +9/-9 supply from a charge pump and sounds super clean with both the audio input and guitar input.  (I found most headphone amps lacked headroom with modern humbuckers and/or didn't take pedals well)

And if not using a breadboard, use sockets where you think you may want to try different caps and/or resistors, saves time and frustration. What sounds great through an amp, doesn't necessarily sound great through a headphone amp. Of course, that's the whole reason for using a cab sim.  

The omnicabsim on the main page may be the way to go for the cab sim if you don't mind all the knobs. You could always start with that and see which settings you prefer, then eliminate all the extras to slim it down if need be. (Personal experience - I had built the original non-commercial version of the omnicab a couple years ago and didn't care for it, preferring the simpler runoffgroove Condor. This version of the OmniCabSim looks much improved and worth a go I think)  

Keep us posted as I'm always looking for more :0)
       

[MAO]

Sorry, one more thing worth mentioning, although probably obvious.

The headphones can make a huge diffence in the final tone. So don't be discouraged if you find some recommendations that don't work out with your setup, just be prepared to tweak some of the values. You may be able to dial it in to your liking.

When I built my first cab sim/headphone amp I was using an expensive pair of Bose headphones, and after a bunch of tweaks, got it sounding really good with those. Then I somehow left those headphones on a plane and replaced them with a pair of Sony's at half the cost. That once good sounding headphone amp was now to dark with the Sony's.  

That's why I think the omnicabsim may be a good fit as its highly tweakable as is, without having to swap out components.

Good luck!

[MAO]

Groovechampion,

Yes, a 386 is a good choice for a mono guitar signal and can also provide some grit. The 5532 is also good choice to drive headphones, especially with a stereo/audio input.

Beside all the layouts, this forum is great place to learn and share experiences. The more questions, the more better :0)

One thing I have learned after many years at this is what makes sense to some, may not make sense to others. And now we have places like this to ask and find out why!

Also, what sounds good to some, may not sound good to you or me as much depends on the gear, tastes and expectations. The more we ask and read, the more we'll be able to tweak things to our liking.

So keep the questions coming :0)

[bones79]

Thanks for all the great info, Mao!
Your Condor layout does sound really good, especially as I also play humbuckers too (sd custom trem + 59). I think I'll stick with your final jamMix layout + a cab sim, as I really want the stereo aux input for playing along with mp3s or a metronome. It's the only vero I've seen with that feature, and I know you've refined it.
The jamMix + omniCabSim could be ideal! Looks very flexible.
I'll be using Audio Technica M40x headphones, fingers crossed they sound good!
Just finishing the Wampler Faux Spring, will then make a start. All the advice is much appreciated!

[MAO]

The faux spring, my favorite brick reverb!

I'll post the combined Condor cabsim/Jammix I'm currently using in case you want to try it. Its 21 x 27.

And yeah, if you do go with just the jammix, dont bother with the original, use the refined version from 03/16.

[MAO]

So in this version, I replaced the Timmy with a modified runoffgroove Condor Cab Sim, pretty much left the rest of the design as is, meaning the audio input, the guitar panning and headphone output.

The Condor mods are based on some comments I found on DIY or FSB I think.

I changed the input jfet stage of the Condor to a buffer as I could not get a completely clean tone using humbuckers with the original design, and also converted the U1A stage to a gain stage along with a pair of clipping diodes. I also went with the "Marshall" voicing as it sounded better with my gear and headphones.    

This JamMan version takes pedals well, and I still like the ability to pan the guitar left or right when playing along with the audio input.  The audio is crystal clear and sounds as good as the source.

It can also be used as a standalone pedal, although limited as there is no external tone control. But I can get 100% clean tones or a good bit of soft clipping with the gain control turned up. Which is useful when I just want to play for a few minutes and not so worried about the tone/distortion. But it certainly sounds better when placed after another pedal.

If considering building this, I would suggest reading the Condor build info for additional tweaks.  

Also, use a switched jack for the audio input so the jack is grounded when nothing is plugged in.  

The controls are straight forward:

Volume - Adjusts the guitar signal's output volume
Balance - Pans the guitar signal left, right, center or anywhere in between
Gain - Adds in the internal gain/clipping circuit, be careful with the volume control when cranking up the gain. (I turn the gain all the way down when using the JamMan with other dirt pedals)

Inputs
Audio In - Stereo jack - plug in a stereo cable from the line out or headphone out jack of a phone, computer, tablet etc. (Be sure the audio device volume is turned down to start)

In - Guitar straight in or from an external effect out jack.

Output
Headphones - Stereo jack  

The audio volume is controlled by the audio device itself...be careful it can get extremely loud!

As for the opamps, I would stick with the 5532, but the TL072s can be any dual opamp of choice. A 1044 for the charge pump would be ok too.



   

[bones79]

Fantastic, thanks so much for that, Mao! I'm going to order the parts I need and start ASAP :)

Is z1 still 9.1v zener 1N4739?

[GrooveChampion]

Dude I built the Faux Spring twice now and it refuses to work. The first time there was simply no signal, the second time there was only a clean signal.

I aint saying the layout is the issue, far from it. If anything I blame my own incompetence for it, I guess it is finicky like PT2399 based circuits, or Fuzz Faces.

[MAO]

I'll be glad to help you troubleshoot it over in the debugging forum it if you like.