Hi all, I am interested in building my first amp, inspired by a Roland Cube but simpler and on wheels with a handle, with an integrated battery that can power the speaker for two hours of busking with an amplified violin.
Dream:
Speaker box with two hours of battery life
One input
Volume knob
Low, medium, and high EQ knobs.
Reverb would be a bonus but I imagine that is trickier.
Is this a reasonable first-time project? I studied mechanical engineering and have basic CAD skills, as well as some basic circuit understanding, but I haven't tackled a project like this before.
Any advice or links much appreciated.
Thanks!
Dream:
Speaker box with two hours of battery life
One input
Volume knob
Low, medium, and high EQ knobs.
Reverb would be a bonus but I imagine that is trickier.
Is this a reasonable first-time project? I studied mechanical engineering and have basic CAD skills, as well as some basic circuit understanding, but I haven't tackled a project like this before.
Any advice or links much appreciated.
Thanks!
I put together a busking amp based on a very simple dual TDA2003 board (not saying it is the best choice, but it's what I had on hand) and the 12v battery from a $20 Harbor Freight electric drill. Disassembling the drill provided the socket for the battery.
The 10 watts was enough with an efficient speaker and the battery was able to drive it at loud volume for 2+ hours.
This was very simple, and you will probably get input here for a better approach to the amp. But I was surprised at what could be done for almost no money. If you want to keep things very simple you may want to consider a pedal for reverb and/or EQ.
The 10 watts was enough with an efficient speaker and the battery was able to drive it at loud volume for 2+ hours.
This was very simple, and you will probably get input here for a better approach to the amp. But I was surprised at what could be done for almost no money. If you want to keep things very simple you may want to consider a pedal for reverb and/or EQ.
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Here's a little more information on the approach to the TDA2003 amp until you get a more knowledgeable suggestion. Prebuilt boards are inexpensive, but this article will help you understand what's going on, and where to start of you want to build from scratch. The appeal to me was the 12v compatibility, and even more so, the fact that a prebuilt board was on the shelf. https://www.circuitbasics.com/complete-guide-to-build-a-10w-amplifier-with-the-tda2003/
Thanks. What would be your hoped for amount of amplifier power (bearing in mind that high power means short battery life)?
Importantly, we need to know your desired enclosure dimensions as this will dictate the diameter of the loudspeaker.
The frequency of the lowest note on the violin is 196 Hz, so low bass response from the busking amp/speaker combo is not a requirement.
I imagine employing a sealed enclosure and a speaker driver having a reasonably smooth frequency response (and not peaking around 2.5 kHz like a guitar speaker does).
Importantly, we need to know your desired enclosure dimensions as this will dictate the diameter of the loudspeaker.
The frequency of the lowest note on the violin is 196 Hz, so low bass response from the busking amp/speaker combo is not a requirement.
I imagine employing a sealed enclosure and a speaker driver having a reasonably smooth frequency response (and not peaking around 2.5 kHz like a guitar speaker does).
Since we are talking battery powered, a class D amplifier module could be a good choice since it wastes less battery energy as heat.
I've seen them complete with tone controls, so I'll have a look around later and see what's available.
P.S. I agree with mbose that we need a speaker driver of high sensitivity in order to extract most sound pressure level per watt of input.
I've seen them complete with tone controls, so I'll have a look around later and see what's available.
P.S. I agree with mbose that we need a speaker driver of high sensitivity in order to extract most sound pressure level per watt of input.
Hi @mbose and @bucks bunny , thanks for the info. I think a drill battery is a great idea!
So, it sounds like I could use a one-channel TPA3116 amp, with knobs for low, mids, and high (although maybe a violin is just midrange) and volume, and then wire it to the drill battery, a 1/4" input jack, and a speaker with frequency response greater than 196Hz to about 5k Hz.
@Galu, thanks so much for your help. I am really not sure what cabinet dimensions, speaker dimension, and specific speaker I should use.
Any advice much appreciated !! I have access to a CNC woodcutter, so if there is a free cad program that I can use to help design the cabinet, I am all ears.
I am building this in Portugal, so if anyone has an idea for good supply shops in europe, please do let me know.
Thank you!!
So, it sounds like I could use a one-channel TPA3116 amp, with knobs for low, mids, and high (although maybe a violin is just midrange) and volume, and then wire it to the drill battery, a 1/4" input jack, and a speaker with frequency response greater than 196Hz to about 5k Hz.
@Galu, thanks so much for your help. I am really not sure what cabinet dimensions, speaker dimension, and specific speaker I should use.
Any advice much appreciated !! I have access to a CNC woodcutter, so if there is a free cad program that I can use to help design the cabinet, I am all ears.
I am building this in Portugal, so if anyone has an idea for good supply shops in europe, please do let me know.
Thank you!!
You might still benefit from a 3 band tone control, although if you are customizing one you might push the turnover frequency for the bass control up a bit. Most of the stuff designed for small speakers/amps has the bass control set “way too high in frequency“ anyway, so it might end up being just what you want. Treble control will always have audible effect, even if the fundamentals are all below a kHz.
Your biggest expense will be a high sensitivity speaker. The best one for the job is about $120 (B&C 8PE21) but it’s WAY overkill on power handling. Unfortunately, getting one that sensitive and that smooth for a 10 watt application is impossible today. In the days of tubes, yeah. Faital Pro makes some nice 6 and 8 inch that are about 95 dB, but even they start at $50. Typical cheap midrange drivers are only about 85, maybe 87 dB. I don’t know if the BOFU clone is any good anymore, but they are priced right ($14). If they give you even 90dB/W/m, it might be a good compromise.
Your biggest expense will be a high sensitivity speaker. The best one for the job is about $120 (B&C 8PE21) but it’s WAY overkill on power handling. Unfortunately, getting one that sensitive and that smooth for a 10 watt application is impossible today. In the days of tubes, yeah. Faital Pro makes some nice 6 and 8 inch that are about 95 dB, but even they start at $50. Typical cheap midrange drivers are only about 85, maybe 87 dB. I don’t know if the BOFU clone is any good anymore, but they are priced right ($14). If they give you even 90dB/W/m, it might be a good compromise.
This TPA3116 based amp has what you ask for, but is dual channel: https://www.ebay.co.uk/itm/20420736...s=ispr=1&amdata=enc:1hCqT9fUGT_GXV_rKDu5ZxQ73
The 5" diameter Celestion TF510 driver has a high sensitivity of 91 dB and is available from Thomann for £35.
It has the required frequency response.
Full specifications here:
https://celestion.com/product/tf0510/
It has the required frequency response.
Full specifications here:
https://celestion.com/product/tf0510/
Well said
speaker sensitivity plays a major advantage
Since bandwidth is more upper range
your not looking for extreme low frequency.
So choices and cabinet design is somewhat more
simple.
Numerous pro sound even some HiFI
8" can be around 92 to 93 dB
some guitar 10" can be well up to 97 dB
high sensitivity yields high sound pressure
volume levels, with lower power.
lower power gives longer battery life.
Diy " bluetooth" speaker designs.
being popular. at least give premade modules
and battery management systems already designed.
most the cost be the battery, and getting nickel and
dimed to death putting a speaker in a box.
speaker sensitivity plays a major advantage
Since bandwidth is more upper range
your not looking for extreme low frequency.
So choices and cabinet design is somewhat more
simple.
Numerous pro sound even some HiFI
8" can be around 92 to 93 dB
some guitar 10" can be well up to 97 dB
high sensitivity yields high sound pressure
volume levels, with lower power.
lower power gives longer battery life.
Diy " bluetooth" speaker designs.
being popular. at least give premade modules
and battery management systems already designed.
most the cost be the battery, and getting nickel and
dimed to death putting a speaker in a box.
I can recommend this 6.5 driver: https://www.amazon.de/IMG-Stage-Line-100PA-PA-Mitteltöner/dp/B002DUGDVU
For ultimate efficiency and wideband: B&C 6X13