headphone amps question

bloodmist · February 16, 2006, 11:16:17 PM

hello, first question... why do people not like helping me? I posted similar questions with my problems with ruby amp and although people helped me, I still have no iudea what is wrong with my ruby amp.
second question...I looked for schematics for headphone amps and found way too many. can anyone suggest an headphone amp which is easy to make, and can be used with other battery powered effects.
3rd q... is ruby amp supposed to be a stand alone or can I plug effects into it? built 2 ruby amps(because noone could help me with the first one) and both don't like being plugged in with another effects(both (effect and ruby) bettery powered on separate batteries). the first version is strange, plugin: guitar pedal amp headphones. everything is dead quiet. plugin: guitar amp effect headphones. very quiet but there is some sound..but it ios very distorted. with the second version in both cases its dead quiet. when plugged straight guitar to amp everything is fine.

if I am asking something stupid or incomprehensable or in a wrong format, please tell me because I am asking questions that are not that hard from my point of view and non the less practically noone can help me.

flibbergibbin · February 16, 2006, 11:31:14 PM

Hope this will help you. I'm quite new here myself so this is the best I can do. As for your questions they'll have to be answered by someone whose knowledable in these things. Anyway the link is quite useful nonetheless.

http://www.generalguitargadgets.com/index.php?option=com_wrapper&wrap=ricardo_practice_amp

coitmusic · February 17, 2006, 01:49:26 AM

First of all, you gotta drop the 'tude,man. If you haven't received a response that is helpful, it may be because you aren't asking the right questions. I just built a couple of Rubys and would be glad to help.

I'm assuming that you followed the instructions on the runoffgroove site... check every connection. Plug your guitar into the amp and wiggle stuff around on the board. If anything changes in the sound, look closer at that point for a bad solder. Look especially at the jacks. I had a hard time wiring these up correctly when I first started electronics. How is your headphone jack connected? Does it break the connection to the speaker? What impedance does your headphones have? This may cause a problem as some headphones have much higher impedance than speakers. Not sure why you would put the effect after the amp...Have you checked the batteries in your effect? try the same set up in a known good amp to check that your effect chain is sound.
Good luck,
Chester

bloodmist · February 17, 2006, 06:40:05 AM

I apologise for being harsh and offensive. Its just that in 3 posts (all had mostly different questions), people have either not answered anything or started helping me and then suddenly disappeared. And the same thing happened on another forum about something else(which was about something very common and still noone answered.) I apologise again. you(coitmusic) on the other hand did exactly what I wanted..gave me a bunch of questions and suggesstions.

yeah,instructions came from runoffgroove and generalguitargadgets.com

impedance on headphones...don't know how to measure it : (...not even sure what exactly impedance is...

headphone jack: no I have no speaker connected to it. only headphones.

battaries checked. everything works with big amp(not-self-made one, with a speaker : ))

why would I use effects with a portable amp? well... I like playing with effects and if I wanted a clean sound I would either play electric without the amp or acoustic...

I will post all info on the 2 rubys and exactly what problems I experience later today because now I have to run....thank you very much for helping, please don't abandon this thread....

lethargytartare · February 17, 2006, 10:56:52 AM

Quote from: bloodmist on February 16, 2006, 11:16:17 PM
hello, first question... why do people not like helping me? I posted similar questions with my problems with ruby amp and although people helped me, I still have no iudea what is wrong with my ruby amp....

So people tried to help you but couldn't, and that means people don't like helping you?!?

Quote from: bloodmist on February 17, 2006, 06:40:05 AM
...impedance on headphones...don't know how to measure it : (...not even sure what exactly impedance is...

google. search on "impedance"

Did you read "what to do when it doesn't work"?

Ge_Whiz · February 17, 2006, 11:41:22 AM

Sometimes folks can't offer help because they've never experienced the problem. My first rule of ROG (and the reason I build so much of their stuff) is that their stuff WORKS. It's not just "here's my idea, please someone build it, debug it, and let us know how good it is because I'm too busy at the moment". They go to enormous efforts to present designs that are reliable, and if yours doesn't work, there is something wrong with your build. The Ruby is designed as a small amplifier to feed a loudspeaker. Using it as a headphone amplifier is something that you've done yourself. Try it as it was originally intended - hook it up to a speaker - first, then try modifying it. Frankly, my Ruby is so loud I wouldn't dare try plugging headphones into it directly for fear of damaging (a) my ears and (b) the headphones.

There is no reason why the Ruby should not work with effects plugged in, but at the input like any other amp. Guitar-effects-Ruby. Having read the 'What to do..." thread, start learning some serious circuit debugging methods. Build an audio probe and learn how to use it - your Ruby is the perfect opportunity. Does the signal get through the input socket to the board? Does it make it out of the source of the FET? Through to the other side of the 47n capacitor? Does it reach the volume control? Does it make it out of the wiper (middle lug)? Does it reach pin 2 of the 386? Is that chip connected up exactly as shown? Have you remembered to earth pin 3 as well as pin 4?

Any small amp chip should make a good headphone amp, but some use fewer additional components than others. Make sure that the parts are still available to buy. Narrow your choice down to a few designs and then post the URLs in your message so that we can go and examine them for you. You can make a reasonable headphone amp with a simple op-amp chip like the 741. I prefer to use an old, obsolete, small power amp IC a bit like the 386, but I always use headphones with an in-line volume control to tame the output.

Relax! We all love you, really.

gez · February 17, 2006, 12:43:48 PM

Quote from: bloodmist on February 17, 2006, 06:40:05 AMIts just that in 3 posts (all had mostly different questions), people have either not answered anything or started helping me and then suddenly disappeared.

In your first thread you stopped replying. I gave you my opinion on what I thought was wrong "might have accidentally wired the LED to the top of the 1M5 instead of ground" but you didn't reply.

twabelljr · February 17, 2006, 12:49:36 PM

Quote from: Ge_Whiz on February 17, 2006, 11:41:22 AM
Sometimes folks can't offer help because they've never experienced the problem. My first rule of ROG (and the reason I build so much of their stuff) is that their stuff WORKS. It's not just "here's my idea, please someone build it, debug it, and let us know how good it is because I'm too busy at the moment". They go to enormous efforts to present designs that are reliable, and if yours doesn't work, there is something wrong with your build. The Ruby is designed as a small amplifier to feed a loudspeaker. Using it as a headphone amplifier is something that you've done yourself. Try it as it was originally intended - hook it up to a speaker - first, then try modifying it. Frankly, my Ruby is so loud I wouldn't dare try plugging headphones into it directly for fear of damaging (a) my ears and (b) the headphones.

There is no reason why the Ruby should not work with effects plugged in, but at the input like any other amp. Guitar-effects-Ruby. Having read the 'What to do..." thread, start learning some serious circuit debugging methods. Build an audio probe and learn how to use it - your Ruby is the perfect opportunity. Does the signal get through the input socket to the board? Does it make it out of the source of the FET? Through to the other side of the 47n capacitor? Does it reach the volume control? Does it make it out of the wiper (middle lug)? Does it reach pin 2 of the 386? Is that chip connected up exactly as shown? Have you remembered to earth pin 3 as well as pin 4?

Any small amp chip should make a good headphone amp, but some use fewer additional components than others. Make sure that the parts are still available to buy. Narrow your choice down to a few designs and then post the URLs in your message so that we can go and examine them for you. You can make a reasonable headphone amp with a simple op-amp chip like the 741. I prefer to use an old, obsolete, small power amp IC a bit like the 386, but I always use headphones with an in-line volume control to tame the output.

Relax! We all love you, really.

Very well said!

coitmusic · February 17, 2006, 01:03:43 PM

A couple more things to think about:

Check the sticky about "if it doesn't work" at the top of the list of the stompbox building page. Very helpful advice here. Especially where it describes the info you need to provide in order to get a helpful response. People are much more willing to help if they can do it in one message instead of back and forthing with you asking a ton of questions.

Also, you say that it works when you plug a speaker in to the out jack, but not when you plug in the headphones. What type of jack are you using? Headphones have a stereo plug on them, speakers a mono. Not sure how, but you may have things crossed somewhere.

Peace,
Chester

bloodmist · February 17, 2006, 02:03:36 PM

yes, I have read the"what if it doesn't work" page. and in one of my posts put all that data and that was one of the posts that some person never came back...
theese are my posts about ruby :
// last 2 posts are mine with questions
http://www.elixant.com/~stompbox/smfforum/index.php?topic=41969.0

//again...asked a few questions and the person didn't reply..
http://www.elixant.com/~stompbox/smfforum/index.php?topic=41305.0

//gez, I truly don't understand what happened... I keep where ever I post in a window which is always open and I just renew it and then after a few days if noone answers I close it... and by the dates I see that you answered right away and then someone else answered. I have no idea why I didn't see it.
http://www.elixant.com/~stompbox/smfforum/index.php?topic=41388.msg298460#msg298460
..wait I did read this.....umm.. sorry, I guess I somehow intended to answer but forgot and then that dude posted right after you and I complely forgot...
compleetely admit my fault. sorry.

man, so many posts. see all I had to do was get some attetude and everyone started answetring.. thank you very much. I will sort through everything in a couple of hours hopefully.(if the heavy wind doesn't rip up the fence again...)

some new observations about the second amp.
plug into a computer speaker(with no sepatrate power supply) and seems to be working but even with practically no gain there is distortion. I think I actually made this one right. but in this one too, when I turn up the gain at a certain point it starts squealing kinda although not very loudly(meaning it is possible to play over it)
..also I just found out that the pedal that I used(dunlop crybaby) just stopped working and I am not sure wether it was before I tested it with the second amp or before so tonight I will test it with something that will work(because to make the second amp I kinda took apart my first creation..electra distortion I think).
oki so by tonight I will post all my findings...(I feel like I will get many more posts by then..)

2gez: no I checked, the led seems to be going to the ground. plus as I seem to remember everything was like that before I put it in.

2coitmusic: hm...umm. no, either all of them work(small headphones, large headphones, speaker) or all of them don't... they do work very differently though... on the second amp, small headphones create a clean sound and speaker with larger headphones create more distorted sound...I am looking into what impedance is.. hopefull will be able to measure it by next post. : )..just checked... the small headphones don't get any distortion even with gain all the way up(and volume all the way down...)

gez · February 17, 2006, 02:44:00 PM

Is there a tried and tested layout for this amp and if so did you use it?

The amp is oscillating, that's what the squealing is. Might be layout...if you attempted one yourself?

bloodmist · February 17, 2006, 03:13:10 PM

layout meaning how the components are positioned in relation to each other? yeah I put them where I thought they would fit better : ) and in the first amp and second I put them down differently.(umm...if yes on the previous qhestion are there any common rules?)to make everything fit together compactly.
also, just finished reading on impedance : ( how the hell can I measure it if it is frequency dependant resistance(meaning different from normal resistance)(sounded sophisticated probably doesn't make sence..: ))so would simply measuring the resistance help?(on headphones and speaker)
next trying to find what audio probe is and how to use it(at the moment I feel like its basically taking the multimeter and measuring wether there is voltage after each component...am I right? anywhere in the vesinity?well if I am I still am not exactly sure how to do that...negative lead on ground and then with positive go along the path of signal?)
inline volume control, I think I have that : )(because I can change the volume: ) but I am not sure what is inline and not inline mean...)
first I put together the shematic by looking at the schematic and the drawing and then connected in volume, gain, and jacks and battery according to:
http://generalguitargadgets.com/index.php?option=content&task=view&id=213&Itemid=238
the PDF in there...

gez · February 17, 2006, 03:29:18 PM

Quote from: bloodmist on February 17, 2006, 03:13:10 PM
layout meaning how the components are positioned in relation to each other?

Yes, exactly that. The chip you're using has a reputation for oscillation so you need to be a little careful how you lay it out. If you haven't done so already, try taking the ground connection from the speaker/phones directly to the -ve terminal of your power supply/battery. Don't share a common ground with the rest of the circuit.

Quotealso, just finished reading on impedance : ( how the hell can I measure it if it is frequency dependant resistance(meaning different from normal resistance)(sounded sophisticated probably doesn't make sence..: ))so would simply measuring the resistance help?(on headphones and speaker)

When people say 'impedance' they usually mean 'input resistance'...it makes like easier. With cans, it might say on them what their impedance is, otherwise measure them (your intuition is doing well

)

Quotenext trying to find what audio probe is and how to use it(at the moment I feel like its basically taking the multimeter and measuring wether there is voltage after each component...am I right? anywhere in the vesinity?well if I am I still am not exactly sure how to do that...negative lead on ground and then with positive go along the path of signal?)

An audio probe is just a probe that connects to your guitar amp so you can hear where you're getting sound (you can plug your instrument in at the input or use a test signal instead). You work your way through the circuit stage by stage until you don't hear anything...this helps isolate the problem. It's not really worth it for this circuit as it's so simple, plus you're hearing something at the output...at least I think you said that (too many threads plus my minds not what it used to be)!

gez · February 17, 2006, 03:38:41 PM

OK, my remarks about oscillation are in reply to comments made in one of your other threads, but presumably you still have this problem (squeal with headphones when you turn it up)?

bloodmist · February 17, 2006, 03:53:25 PM

resistances:
small headphones: 40ohms 8o
big headphones: 5 ohms (I changed the cable on them and both speakers are fed through the same line now : ))
speaker: about 10 ohms(it was so funny, I moved the probes and it made sound : ))) I am so amused : ))
so this now explains why there is heavy distortion on the speaker/big phones and no distortion on small ones.

yeah.. both of them do just that one does it more than the other. whew...umm lemme think what it is that you mean in there...umm..don't all the grounds have to be connected? they are in the layout.
so you mean connect the ground connection of input jack to the negative connection from the battery?(just checking if I understand what exactly you are saying : ))

gez · February 17, 2006, 04:03:11 PM

Quote from: bloodmist on February 17, 2006, 03:53:25 PM...umm..don't all the grounds have to be connected? they are in the layout.

Ultimately, yes, all grounds get connected. However, it's not a good idea to share the same trace/wire for things like the output ground connection of a speaker and the input ground connection, that way you can generate feedback. What I'm suggesting is you take the ground connection for the speaker directly to the battery terminal, don't connect it to a trace that gets used as ground for the main body of the circuit.

bloodmist · February 17, 2006, 04:13:51 PM

nope sqealing is still there once you reach a certain point in volume.

gez · February 17, 2006, 04:14:56 PM

Did you perf this? If so, there's a layout at Runoff you could try.

bloodmist · February 17, 2006, 04:20:40 PM

well I kinda went semi with that layout... only I put my transistor under the IC not above and the .047 capasitor which supposed to be on top of the transistor went under it(if looking at the layout.)

gez · February 17, 2006, 04:22:18 PM

Quote from: bloodmist on February 17, 2006, 03:53:25 PM
resistances:
small headphones: 40ohms 8o
big headphones: 5 ohms (I changed the cable on them and both speakers are fed through the same line now : ))
speaker: about 10 ohms(it was so funny, I moved the probes and it made sound : ))) I am so amused : ))
so this now explains why there is heavy distortion on the speaker/big phones and no distortion on small ones.

I've checked a data sheet for the LM386 and at 9V typical output power is only 700mW. With a 5 ohm load you're going to exceed its capabilities at high gain settings. Sounds as though the same is happening with the 10 ohm load too...though I'd have thought that would have been ok.

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headphone amps question