Hello everyone,
It's late so I'll keep it short. The DIY bug is coming back and I was wondering if I could build a an amp that would fit into an old guitar (saw out an extra hole) and fit in a speaker as well.
I know it's a terrible idea and it'll sound like hell, but I'm making this just as a novelty no matter how poor the quality. I'd like to learn more about amps and try and make them go at low voltages (12v?)
I could use some pushes in the right direction though as I'm unfamiliar with designing my own schematic.
I've built a few headphone amps (followed others schematics), speakers,... currently I'm in my second yearl engineering in college and I just chose to major in electronics, alas specific courses only begin next semester so my knowledge is quite small.
I know my wa around the basic stuff, but I'm way to underqualified to make my own schematics that are more complicated than a cmoy.
Any help would be very much appreciated 😀
Dries
It's late so I'll keep it short. The DIY bug is coming back and I was wondering if I could build a an amp that would fit into an old guitar (saw out an extra hole) and fit in a speaker as well.
I know it's a terrible idea and it'll sound like hell, but I'm making this just as a novelty no matter how poor the quality. I'd like to learn more about amps and try and make them go at low voltages (12v?)
I could use some pushes in the right direction though as I'm unfamiliar with designing my own schematic.
I've built a few headphone amps (followed others schematics), speakers,... currently I'm in my second yearl engineering in college and I just chose to major in electronics, alas specific courses only begin next semester so my knowledge is quite small.
I know my wa around the basic stuff, but I'm way to underqualified to make my own schematics that are more complicated than a cmoy.
Any help would be very much appreciated 😀
Dries
I'm no guitarist, but I suspect feedback could be a problem if the speaker is mounted inside the guitar! (That is an example of the sort of understatement which English physicists love to make).
Feedback..hmm that could be a problem but I'm not sure. If I'm correct feedback happens when the signal from a speaker reaches the microphone and amplifies itself again and again and again...
But in this case the sound from the speakers need to vibrate the strings to get back into the input or the speakermagnet could interfere with pickups from the guitar.
I've tried to google it and see what pops up but maybe someone else can help with this?
But in this case the sound from the speakers need to vibrate the strings to get back into the input or the speakermagnet could interfere with pickups from the guitar.
I've tried to google it and see what pops up but maybe someone else can help with this?
This is not a new idea, in fact it's already been done several times. But probably not with tubes, only SS. You can find them on eBay. They even have amplifiers in guitar carry bags or cases.
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Well the hardest part would be getting a power transformer in there. Its doable.
I know that you could use 50EH5, but don't unless you have an isolation transformer.
Build something along the lines of a Fender Champ. If you rectify with SS it only has two tubes.
I know that you could use 50EH5, but don't unless you have an isolation transformer.
Build something along the lines of a Fender Champ. If you rectify with SS it only has two tubes.
If you SS, just hack something apart for it's chipamp or opamps, then google the datasheet. Some of the datasheets have simple schematics in them. You can even "stack" the opamps.
Distortion can be simulated by using a pair of diodes. This will clip the signal when it diodes start to conduct. One diode is "reversed from the other", to clip either end of the AC signal. Were it's placed in the circuit will be depend on what you pick (ie: feedback loop etc)
Modern silicon diodes clip (distort) at the highest voltage (out of common diodes) and clip hard. More suited for heavier sound.
Germanium diodes, the little glass ones you used to see will clip a little sooner and softer resembling a tube amp.
That's if you even want distortion. That's how "real" SS amps distort, so your project will sound surprisingly good, for a SS amp that is.
Have fun.
AL
Distortion can be simulated by using a pair of diodes. This will clip the signal when it diodes start to conduct. One diode is "reversed from the other", to clip either end of the AC signal. Were it's placed in the circuit will be depend on what you pick (ie: feedback loop etc)
Modern silicon diodes clip (distort) at the highest voltage (out of common diodes) and clip hard. More suited for heavier sound.
Germanium diodes, the little glass ones you used to see will clip a little sooner and softer resembling a tube amp.
That's if you even want distortion. That's how "real" SS amps distort, so your project will sound surprisingly good, for a SS amp that is.
Have fun.
AL
Yeah, you can't get a lot of volume with a hollow-body guitar with a speaker in it. but a solid body might be something to play with. I know I've seen a thread in recent months on this (some commercial Fender(?) model with an amp and speaker build into a solid body), I think in the musical instruments subforum (where this thread sorta belongs).
I'd rather not have a tube amp inside a guitar I'm playing, for both the heat generated and the high voltage. I suppose it could be done, but I'd be reluctant to play it for more than a minute.
I think the "best" solution is a battery-powered Class D amp and speaker in a solid body, with the preamp having whatever distortion-generating circuitry you want or need. Use Class D to get the best combination of power and battery life.
I'd rather not have a tube amp inside a guitar I'm playing, for both the heat generated and the high voltage. I suppose it could be done, but I'd be reluctant to play it for more than a minute.
I think the "best" solution is a battery-powered Class D amp and speaker in a solid body, with the preamp having whatever distortion-generating circuitry you want or need. Use Class D to get the best combination of power and battery life.
Ah heck it's just for fun, put tubes in it with a clear pick-guard. Not a gigging axe, although it would be fun.
As far as feedback, you should be OK in a solid body, a hollow body would have to be stuffed.
I hope they don't put your thread there, it's a desert.(musical instruments)
I'm assuming you want tubes because you posted it here, in the DIYaudio Tube forum. This is were those types of questions would be best answered.
Or just lie and say your building a mono amp and you can stay 🙂
As far as feedback, you should be OK in a solid body, a hollow body would have to be stuffed.
I hope they don't put your thread there, it's a desert.(musical instruments)
I'm assuming you want tubes because you posted it here, in the DIYaudio Tube forum. This is were those types of questions would be best answered.
Or just lie and say your building a mono amp and you can stay 🙂
Since the moderators started forcing guitar related gizmos into that forum, the desert has become populated with a few oasis. I find myself looking there about as often as I come here.
I have been working on one for about 3 years. When I run up against a road block I put it aside where it has been for most of this year.
There have been speaker and amp inside guitar designs for as long as I can remember. None have been commercially sucessful. I played one in the Lafayette Radio and Electronics store in Miami in about 1968. Of course the amp was solid state and it wasn't very loud since it was designed for practice.
This is what I have found so far:
Feedback is a real issue with the speaker mounted in the guitar body. There are three kinds of feedback to deal with here and all of them are an issue in a design like this.
Acoustical feedback:
This is commonly used to add coloration and infinite sustain in extremely loud rock and metal music. The sound waves from the speaker system will cause parts of the guitar like the strings, neck, and the entire body to vibrate. The energy will excite the strings which will of course be amplified and emerge from the speaker to create a TUNED positive feedback system. A bit of positive feedback lowers the system losses allowing the strings to vibrate for longer than they would if they were picked without feedback increasing the sustain of a note. Turn things up more and the strings will play themselves, but the system is still tuned and controllable by the player.
Mechanical feedback:
Similar to the acoustical feedback path, except that the losses associated with the sepaker vibrations travelling through the air to the guitar body are eliminated. To see this in action set your amps speaker cabinet on a towel or something that would allow it to vibrate more than setting it on the floor, and touch the guitars headstock to the cabinet. Play the guitar and turn up the volume. You will reach a point where the sustain grows longer, turn it up louder and it will become infinite. Turn it up louder and it will break into an uncontrolled trainwreck.
Electrical / magnetic feedback:
There is a coil of wire inside the speaker. You are stuffing watts of electrical energy into that wire which gets turned into magnetic energy that works against the speaker magnet to move the cone. Some of that magnetic energy will be radiated out of the speaker.
There is another coil of wire inside the guitar pickup that is designed to turn vibrating strings inside a magnetic field into electrical energy. When the pickup gets into the speakers magnetic field a transformer is created 9two coupled coils) leading to UNTUNED uncontrollable feedback. This will occur even if there are no strings on the guitar. it will cause a squeal, or high frequency blocking type of distortion. In extreme cases with powerful amplifiers blown parts is possible.
Here humbucking pickups are your friend. Keep the speaker as far away from the pickups as possible. I have found that in the lower wing of an assymetrical flying V type guitar body works best.
Acoustical and mechanical feedback will limit the volume level of a system like this. You can get quite loud, but it will never be a stage guitar unless miked like an acoustic.
It would be wise to experiment with the various feedback mechanisms to be familiar with the problems before building anything. Otherwise this will be a multi year long project like mine. Breadboard and test amplifiers before commiting the design to a guitar body. If your amp can't function when mounted to a piece of wood with a speaker bolted to it, don't waste time making it into a guitar. In fact screw the amp, the speaker and a pickup to a 1" X 4" by 4 foot pine of poplar board and mount a string or two to it. Keep the amps OPT away from the pickup, and rotate it for minimum electrical feedback!!!!! (yes I learned the hard way)
The amplifier must be designed for low power consumption and heat generation. These are kind of a problem with a tube amp, but not impossible to overcome. I have been experimenting with different types of amps.
At first I tried the tubes designed for battery operated portable radios (1U5 and 3V4). They consume the lowest heater / filament power, but have the lowest gain and power output and most are quite microphonic. Yes the amp can squeal all by itself without being connected to the pickups. I have put this path aside for now. I ran the filaments all in series, and made a small inverter for the B+ (90 volts) and ran the whole thing from two series connected cell phone batteries (7.2 volts). Run time per charge was about 3 hours.
I have since discovered the LIPO batteries used by the model aircraft hobby. These have extreme energy densith and light weight. They are however volatile and can burst into flames or explode if mishandled or improperly charged. You must use the correct charging circuit, and you must cease discharge at a fixed voltage point. The cells are thin and flat. I am using a 7.2 volt 2 call battery, but I plan on switching to a 3 cell.
With this power source it is now possible to put a 2 to 5 watt tube amp inside a guitar body. I am still experimenting on the best way to do that. Subminature tubes like the 5718, 5840, and the 6021 are your friend in the preamp section. I am currently using 6AK5's for the output tubes but I want more power!!!
Finding a tiny OPT is a challenge. A tiny power supply toroid is probably the best choice, but I am still using a 70 volt distribution transformer from parts express.
The guitar itself must be modified to fit all the electronics. The thickness is an issue, so I have been making my own bodies. They are about 2 1/4 inches thick. They are made by laminating 3 layers of 1 X 6 inch poplar together. This limits the depth of the speaker. Tiny speakers are not efficient, so it won't be screaming loud.
Of coarse feedback will be an issue at some point or power level.
Finding a tiny SE OPT is a problem?
I think the OP is just looking for a novelty project to get back into DIY.
I would expect it to be ugly and noisey having some parts surface mounted or sticking out.
Decouple the speaker some and you will be fine at bedroom levels.
Finding a tiny SE OPT is a problem?
I think the OP is just looking for a novelty project to get back into DIY.
I would expect it to be ugly and noisey having some parts surface mounted or sticking out.
Decouple the speaker some and you will be fine at bedroom levels.
Low voltage otl with inverter..
high resistance speaker..
SS has been done lots of times..
http://www.youtube.com/watch?NR=1&v=2BItidsQz0s
Try a mains Tx for a laugh as O/P Tx
What about SS hybrid with O/P Tx using low voltage tube preamp..
http://diyaudioprojects.com/Tubes/6418-Tube-Preamp-Headphone-Kit/
Just ideas..
Regards
M. Gregg
high resistance speaker..
SS has been done lots of times..
http://www.youtube.com/watch?NR=1&v=2BItidsQz0s
Try a mains Tx for a laugh as O/P Tx
What about SS hybrid with O/P Tx using low voltage tube preamp..
http://diyaudioprojects.com/Tubes/6418-Tube-Preamp-Headphone-Kit/
Just ideas..
Regards
M. Gregg
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Hey guys,
Wow! Thanks all for the responses, I'm just on the web so I haven't thoroughly read the long ones but when I get home I will.
About the 'it's been done before': Ofcourse is has been done before 😀 almost anything has, but it's 'uncommon' and thus a great topic to talk about/show with/to friends.
SS would indeed be the way to go if I really want it to be decent but I thought those would be more common then the usage of Tubes. Which is why I thought I'd give the whiole tube idea priority.
I came to think of it because I saw this a long time ago.
It's not the exact pic (I think the one I saw ran of 9v battery!).
These things must sound horribly, lots of distortion on such a low voltage and it's for headphones (in this case).
But maybe I might give something likewise for guitar amps a try. I'm not yet familiar with guitar amps so I'm sure there are quite a few setbacks that'll pop up.
But remember this isn't really to get 'good' quality, as long as it amplfies and the signal from the guitar doesn't just fall into the distortion: I'm happy.
Some are talking about High voltages, but that's clearly something I'd like to avoid. I haven't worked with them and I'd NEVER want to swing them around on a guitar.
That's the main reason I came to the Tubes section: I hoped you guys have some knowledge of tubes that work on extremely low voltages (I can always just plug in a wallwart, but it'd be awesome to have it run on batteries no matter how awful the batterylife is). I'm hoping they're out there and that they can be used for this purpose.
But please remember: as long as they amplify a decent amount (enough for a built in speaker) that should be enough, even if the quality terrible according to normal amp standards.
Expensive tubes are also not that welcome, this is an 'in between' kind of project and has to be nothing more than looking pretty and working. So I'm not planning on spending alot on this.
Thank you everyone for your input 😀 this really helps
EDIT: I think globug got me
Dries
Wow! Thanks all for the responses, I'm just on the web so I haven't thoroughly read the long ones but when I get home I will.
About the 'it's been done before': Ofcourse is has been done before 😀 almost anything has, but it's 'uncommon' and thus a great topic to talk about/show with/to friends.
SS would indeed be the way to go if I really want it to be decent but I thought those would be more common then the usage of Tubes. Which is why I thought I'd give the whiole tube idea priority.
I came to think of it because I saw this a long time ago.
It's not the exact pic (I think the one I saw ran of 9v battery!).
These things must sound horribly, lots of distortion on such a low voltage and it's for headphones (in this case).
But maybe I might give something likewise for guitar amps a try. I'm not yet familiar with guitar amps so I'm sure there are quite a few setbacks that'll pop up.
But remember this isn't really to get 'good' quality, as long as it amplfies and the signal from the guitar doesn't just fall into the distortion: I'm happy.
Some are talking about High voltages, but that's clearly something I'd like to avoid. I haven't worked with them and I'd NEVER want to swing them around on a guitar.
That's the main reason I came to the Tubes section: I hoped you guys have some knowledge of tubes that work on extremely low voltages (I can always just plug in a wallwart, but it'd be awesome to have it run on batteries no matter how awful the batterylife is). I'm hoping they're out there and that they can be used for this purpose.
But please remember: as long as they amplify a decent amount (enough for a built in speaker) that should be enough, even if the quality terrible according to normal amp standards.
Expensive tubes are also not that welcome, this is an 'in between' kind of project and has to be nothing more than looking pretty and working. So I'm not planning on spending alot on this.
Thank you everyone for your input 😀 this really helps
EDIT: I think globug got me
Dries
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I need to start a separate thread on this Kent amp I found cheap at a thrift store. It's a piece of junk I thought "too lightweight to be a tube amp", but I looked in the back and saw toobs (!) so I bought it - I'd post a pic of the schematic, except I'd be afraid someone would want to build it. It's only got one transformer (it's small), and it connects to the 3-inch AM radio speaker...
I don't see how this is a lie.
This IS a mono tube amp, isn't it?
I don't see how this is a lie.
tubelab.com you're a hero ! I knew there were others out there that must have tried it.
I will keep looking into it, but I'm sure you just saved me alot of trial and error, for that I am greatly appreciative.
I'll see what I can do about a schematic concerning those lightweight tubes (it's not meant for stages, room volumes are more then sufficient). I'm not sure if I'll go with LiPo's I've worked with them before (and with there dangers) and I never use them if I can't find a suited powering circuit.
I'm amazed that you already got 3 hours out an amp like that!
Please do keep me updated if you find anything new. Do you happen to have a build log concerning your own try?
I will keep looking into it, but I'm sure you just saved me alot of trial and error, for that I am greatly appreciative.
I'll see what I can do about a schematic concerning those lightweight tubes (it's not meant for stages, room volumes are more then sufficient). I'm not sure if I'll go with LiPo's I've worked with them before (and with there dangers) and I never use them if I can't find a suited powering circuit.
I'm amazed that you already got 3 hours out an amp like that!
Please do keep me updated if you find anything new. Do you happen to have a build log concerning your own try?
Hey guys,
I've drawn something based on the things I read this weekend. Keep in mind that this is the first go at trying to understand these schematics (not to mention draw one)
It's been a pain this week to find any good sources on the web to explain these things to me in a not too complicated way, so if anyone knows any good sources, please do share.
I've drawn something based on the things I read this weekend. Keep in mind that this is the first go at trying to understand these schematics (not to mention draw one)
It's been a pain this week to find any good sources on the web to explain these things to me in a not too complicated way, so if anyone knows any good sources, please do share.
An externally hosted image should be here but it was not working when we last tested it.
freestompboxes.org • View topic - "Superfly" - submini tube version of Doug H's Firefly that might be helpful, it uses a 555 timer in a switched mode supply to get a high voltage (170 ish think) or if your completely against high voltage, http://www.sophtamps.ca/mambo/index.php thats what got me started with tubes.
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