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Building a small "travel" amp

dindinbre

dindinbre

Aug 2, 2017
356
352
Serbia
#1
I live in small village, but due to school i spend weekdays in town that is 30 miles away. I go home during weekend and holidays. I just cant carry my KB60 around;its heavy, big and I already carry bass and bags around (I don't drive,damn Serbian laws). I can't find anything prebuilt that does what I need for small amount of money. So i got an idea; why wouldn't I just build one for myself? I can find this kind of stuff dirt cheap:
cebek-e-11-mono-roadpower-audio-power-amplifier-module-20w-rms.jpg

Just build a small box, put any small speaker (I have some kind of car speakers at home), make power and bass inputs, add battery connection, and there it is. Will this work? I don't need it to be loud, just enough to practice.
 
#2
Your bass will sound a lot better through headphones than a tiny low power combo amp. That's the way I go when I travel. I use a tiny headphone amp that makes the bass sound glorious through headphones. And it includes a side jack for MP3 or streaming input. The tiny combo idea works better with a guitar, which doesn't require production and transmission of low bass frequencies. For bass, it's likely to sound underwhelming.
 
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#3
I have tried using headphones, but I dont feel like it is a thing for me. I daily have headphones on my head for about 4 hours. I mean I can use my "little invention" as portable speaker, so it has another +1. Just want to know if I could damage something with my bass.
 
#8
dindinbre said:
Will this work? I don't need it to be loud, just enough to practice.
Click to expand...

I guess that depends on what "it" is. I've tried using a small amplified speaker designed for plugging into headphone jack with my electric-acoustic bass guitar and I didn't get much volume out of it. My speaker does fine when used as intended, when plugged into a headphone jack, but not great when plugged into my bass guitar.

I was able to get sound, and nothing was damaged, but I could barely hear it. If you build something then make sure it's designed for a guitar otherwise you might find yourself disappointed in the results. I see that you don't need it loud but it's more than a matter of being a powerful enough amplifier, there's the matter of the amplifier designed to take in the very small signal of a guitar and make it big enough to move the speaker so you can hear it.

A headphone output can typically produce about 2 volts but a guitar pickup will produce something like 1/10th of a volt. If the amplifier is expecting 2 volts at maximum volume but gets only 1/10th then that's like only being able to turn the volume knob to 1/20th the maximum.

If you want to build your own amplifier from a kit to save some money and learn some electronics then I think that is a great idea. I just don't want to see you get the wrong kind of kit, waste your time and money, and perhaps learn the wrong lesson from the experience. Going cheap can get expensive quick if you don't buy the right tool for the job in the first place.

Also, if you are going to power this from batteries then you also have to make sure the batteries are big enough. It's not just the voltage needing to match but the batteries need to be able to supply enough current, and be able to do so for as long as you need them to.
 
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#9
I know basic electronics and how stuff works. I have an active bass, I get decent sound with headphones directly into bass, but only left channel cos mono. Volume i expect should be enough to fill a room with sound without distortion, but not louder than human voice during normal conversation
 
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#11
dindinbre said:
I know basic electronics and how stuff works. I have an active bass, I get decent sound with headphones directly into bass, but only left channel cos mono. Volume i expect should be enough to fill a room with sound without distortion, but not louder than human voice during normal conversation
Click to expand...

My bass guitar has an active pickup too, and plugging it into an amplifier designed for headphone output did not work well for me. I don't know how much electronics you know so I made some assumptions based on your comments, don't feel offended if you think I "dumbed it down" too much for you. Just so you know where I'm coming from I know some electronics too. I built some electronics kits and wired up some stereos. I also have a bachelor degree in electrical engineering. I'm very new to playing bass though. From personal experience I can say that my experiments with amplified speakers did not go as well as planned as I had no way of knowing how much output I could get from my guitar until I tried, I could not find a specification sheet for the electronics in my guitar.

I still believe you need to take care in choosing the amplifier you use, just because you can get sound from headphones plugged in directly to the guitar does not mean the guitar will be able to drive the amplifier properly.
 
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#12
I was looking at my little 20w practice amp the other day, and the amp portion is pretty damn small, and round here it's pretty easy to find low powered practice amps for damn all money. Also for damn all money are basic small hifi speakers. Suppose you combine. Obviously at any volume you'll blow cone across the room, but if you're careful, and you have a spare driver for first mistake. And if all else fails put original back together.
 
#13
Common Tater said:
My bass guitar has an active pickup too, and plugging it into an amplifier designed for headphone output did not work well for me. I don't know how much electronics you know so I made some assumptions based on your comments, don't feel offended if you think I "dumbed it down" too much for you. Just so you know where I'm coming from I know some electronics too. I built some electronics kits and wired up some stereos. I also have a bachelor degree in electrical engineering. I'm very new to playing bass though. From personal experience I can say that my experiments with amplified speakers did not go as well as planned as I had no way of knowing how much output I could get from my guitar until I tried, I could not find a specification sheet for the electronics in my guitar.

I still believe you need to take care in choosing the amplifier you use, just because you can get sound from headphones plugged in directly to the guitar does not mean the guitar will be able to drive the amplifier properly.
Click to expand...
I am not offended at all :) I like this forum cos there are many guys like you who want to help and whatever I ask someone will jump in and try to make things more clear. Thank you all on that :) I am third year of electrotechnic high school, I know basic electronics (how diodes, transistors and integrated circuits work) and how AC power works. I want to buy completed board, they can be found for 3 euros. I have speakers that should do what i need. I am aware of low frequencies destroying speaker, so I will squeeze them a bit.
 
#14
JimChjones said:
I was looking at my little 20w practice amp the other day, and the amp portion is pretty damn small, and round here it's pretty easy to find low powered practice amps for damn all money. Also for damn all money are basic small hifi speakers. Suppose you combine. Obviously at any volume you'll blow cone across the room, but if you're careful, and you have a spare driver for first mistake. And if all else fails put original back together.
Click to expand...
People ask too much for stuff over here. Small combo amps are 80+ euros. I don't have that much money right now + bass is my hobby atm, nothing serious.
 
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#15
dindinbre said:
I am not offended at all :) I like this forum cos there are many guys like you who want to help and whatever I ask someone will jump in and try to make things more clear. Thank you all on that :) I am third year of electrotechnic high school, I know basic electronics (how diodes, transistors and integrated circuits work) and how AC power works. I want to buy completed board, they can be found for 3 euros. I have speakers that should do what i need. I am aware of low frequencies destroying speaker, so I will squeeze them a bit.
Click to expand...
Glad to hear it, if you are able to apply your education to building your own amplifier then you will do well in the future. You shouldn't be too concerned about speaker damage if the picture you gave is representative of the kit you are getting. It looks like that kit can put out maybe 5 or 10 watts and you mentioned using a speaker rated for 25 watts. I doubt that such a kit amplifier could damage that speaker at any frequency.
 
#16
dindinbre said:
I know basic electronics and how stuff works. I have an active bass, I get decent sound with headphones directly into bass, but only left channel cos mono. Volume i expect should be enough to fill a room with sound without distortion, but not louder than human voice during normal conversation
Click to expand...
For about $6 you should be able to buy or build a "Y" adapter that will send your bass signal to both ears in your headphones. Then you'll have $14 left over to spend on batteries for the bass, which you will be needing!
 
#17
dindinbre said:
I live in small village, but due to school i spend weekdays in town that is 30 miles away. I go home during weekend and holidays. I just cant carry my KB60 around;its heavy, big and I already carry bass and bags around (I don't drive,damn Serbian laws). I can't find anything prebuilt that does what I need for small amount of money. So i got an idea; why wouldn't I just build one for myself? I can find this kind of stuff dirt cheap:View attachment 2841462
Just build a small box, put any small speaker (I have some kind of car speakers at home), make power and bass inputs, add battery connection, and there it is. Will this work? I don't need it to be loud, just enough to practice.
Click to expand...
I play at home running my Avalon u5 di with headphones.
 
#18
If you don't already have this kind of gear it will most likely be too expensive but if you've already got a preamp effect pedal like the ZoomB1on and a rechargable speaker with any Aux input you can get acceptable sound at talking levels. Here's my travel practice rig below. Bass into B1on then into Sony SrsX2. I also plug my tablet into the Sony and jam along to tracks.

20161216_094253.jpg
 

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