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Busking Amp for Bass & Vocals

Started by Puguglybonehead, October 02, 2021, 07:30:43 PM

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Puguglybonehead

I've been building pedals for years now and built several guitars over the last few decades but I've never built anything amp-wise other than a very dirty sounding little LM386 amp.

My sweetheart and I were trying out and admiring our neighbors' Yorkville portable/rechargeable PA. It's the ultimate thing for busking. Can handle a guitar, bass and microphone all at once. (while disturbing the entire neighborhood for a 3 block radius) Runs for at least 4 hours on a charge. Wonderful thing, but the $700 price tag is just out of our range for something that would only get used for a handful of gigs per year.

I'm sure I've got at least one or two TDA2003 power amp kits around here somewhere. Rated at 10 watts or something. I was going to use a FET based amp-sim kit as a preamp along with an 8"/25-watt guitar speaker. (there are some nice, efficient ones available now) That would take care of my guitar well enough for busking.

I have a 2x/bridged TDA2003 kit here as well. Claims to be 20 watts. If I used that, with preamps on two separate inputs, would that be enough for bass and vocals? I was thinking of using a 10" bass speaker (Eminence has some nice ones) and maybe a smaller speaker with a crossover as well. (I know nothing about crossovers but it would be a good thing to learn) Would I need more power for busking with bass?

Would I be better off using the 2xTDA2003 amp as the guitar amp? Would I be in danger of blowing the 25-watt speaker?

Also concerned about current consumption. There are 12-volt gel-cell options and there are now plenty of lithium-ion options thanks to 10+ years of e-bikes everywhere.

Jazz P Bass

Sounds like a fun project.
The real issues will be the cabinet & the recharge circuit.

Alesis has a 25 w/ 50 w peak amp for under 200 US.
https://www.sweetwater.com/store/detail/TransActW2--alesis-transactive-wireless-2

Enzo

Projects are great, but if you only do a few gigs a year, consider renting something for them.

Tassieviking

There are plenty of circuits out there to find, just google busking amp circuit, then try them out.
It sounds like a small mixer desk might be worth a look, I know people have used the old Sunn Alpha powered mixer for guitars in the past.
I'm not suggesting that the Sunn Alpha would suit you, but looking at the circuit might give you some ideas.
You can easily incorporate some stomp box circuits into it as well, like reverb, chorus etc.
Do you have a battery operated drill ? Or any other portable power tools ? Nice portable battery packs.
You can get adapters to fit portable drill battery packs so you can use the batteries for other things.
Good luck with your project, please keep the post going if you proceed.
There are no stupid questions.
There are only stupid mistakes.

Puguglybonehead

Thanks for the advice. I'll definitely keep searching for ideas. I would just go out and buy a ready made system but I'm not liking the look of most of what's out there. Speakers are always too small (for bass) and usually too few inputs. A mixer section is definitely something I'm thinking of. Possibly adding a reverb for vocals as well. As for power tool batteries, I've got a couple around here but I'm doubtful of their current capacity. They've been sitting unused for some time. Might just go the gel-cell route.

joecool85

Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Tassieviking

Another small amp module I think might be good is the TPA3116D2, very cheap on Ebay ($8 up).
In stereo at 12 volts it can go up to 15 watts per channel into 4 ohm speakers.
If you needed more power you could use 2 x 12 volts batteries for 24 volts, then you can get 60 watts per channel into 4 ohm speakers
If you do go with a stereo amp module you could run one channel Bass amp and one for voice / guitar, 2 different speakers.
The TPA3116 can run on 4.5 volts to 26 volts.
I have 2 100 watt mono  modules I bought ages ago, they are small enough to fit into a 1590B stomp box, I was thinking of using one with a laptop power supply for a small pedal amp.
I think that would go nicely with the Sunn Beta preamp pedal I made.
There are no stupid questions.
There are only stupid mistakes.

Tassieviking

If you are busking I imagine you might be doing it mainly during the day, have you considered a small solar cell ?
You can get a 20 watt panel that would be smaller then the top of a small amp with a 10" speaker in it.
The solar panel would continuously top up the battery as you are using it, you might possibly be able to use a smaller battery.
The solar panel does not need to supply enough power for continuous use, just enough to prolong the use, ie. using 2 amps playing and putting 1 amp back in at the same time. And the solar panel keeps working while you have a break.
Just a crazy thought that popped into my mind.
There are no stupid questions.
There are only stupid mistakes.

Tassieviking

I just looked at the TDA2003 spec sheet, it looks like you would get 4 watts at 12 volts, not enough for bass in my opinion, but I am not an expert.
If you have the kit, build it and run your send/line out/ to effects output of your amp into it, and run the output to a separate cab and see what it sounds like.
Or get the signal from your stereo/phone/MP3 player and try it, see how loud the music sounds.
If its not enough the just get another amp module, like I mentioned before, the TPA3116D2 has 15 watts at 12v on the spec sheet at 4 ohm speaker.
You will not us a lot of extra power with a TPA3116D2 if you keep the volume down.
Class D power amps are very efficient and only use a bit more then what you use, if you use a 100w class D amp and only turn it up to 10Watt you will only use about 12-13 watts of power, at least that's my understanding.
Check the spec sheets of the power amp you are thinking off using and find the power rating for the voltage you intend to use, that's what I would do.
Class D amps don't need big heatsinks as well which saves money and weight.
There are no stupid questions.
There are only stupid mistakes.

joecool85

Quote from: Tassieviking on October 12, 2021, 12:39:11 PM
I just looked at the TDA2003 spec sheet, it looks like you would get 4 watts at 12 volts, not enough for bass in my opinion, but I am not an expert.
If you have the kit, build it and run your send/line out/ to effects output of your amp into it, and run the output to a separate cab and see what it sounds like.
Or get the signal from your stereo/phone/MP3 player and try it, see how loud the music sounds.
If its not enough the just get another amp module, like I mentioned before, the TPA3116D2 has 15 watts at 12v on the spec sheet at 4 ohm speaker.
You will not us a lot of extra power with a TPA3116D2 if you keep the volume down.
Class D power amps are very efficient and only use a bit more then what you use, if you use a 100w class D amp and only turn it up to 10Watt you will only use about 12-13 watts of power, at least that's my understanding.
Check the spec sheets of the power amp you are thinking off using and find the power rating for the voltage you intend to use, that's what I would do.
Class D amps don't need big heatsinks as well which saves money and weight.

This is correct.  One thing to note though is the TPA3116D2 is an SMD component and difficult to solder.  TPA3122D2N is a through-hole component and much easier to work with.  There are several kits available with this chip, or you could do something on your own.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Puguglybonehead

#10
Thanks for the advice on the TPA3116D2 and the TPA3122D2N. I will definitely look into those. If I use it with a trimpot controlling output I should be able to conserve battery life and avoid ugly clipping as well, no? I will probably use the TDA2003 module I have here for just a guitar amp. 4 watts with a good speaker and a good preamp should be enough for guitar alone.

Puguglybonehead

#11
Still haven't made progress with this project yet due to being sidetracked with other problems. I've decided that building a busking amp for just the guitar or maybe guitar and vocals would be a better approach for now.

I was considering using this Blues Breaker pedal kit as a guitar preamp. (I like the sound)

https://www.musikding.de/docs/musikding/breaker/breakerschalt.pdf

I already have a premade TDA2003 board around that I could use for a power amp.

https://www.jameco.com/z/VM114-Velleman-7W-Amplifier-Kit-Assembled_2151881.html

Or I could go with this TPA3122 kit to have a channel for guitar and a channel for a mic. 

https://www.parts-express.com/Sure-AA-AK32151-2x15W-Class-D-Stereo-Power-Amp-Kit-TPA3122-320-322

I was just wondering if I would need a buffer between the Blues Breaker and the power amp board?

joecool85

No buffer needed between the power amp and the preamp (Bluesbreaker).  That said, I've never used a BB as a preamp.  You won't know if you like it till you try it.  My guess, you won't have enough tonal control.  You like the sound of them which is great, but you don't send it into a flat eq'd amplifier - you send it to a guitar amp.  Even when you set a guitar amp eq to look flat, it has a large mid cut and sometimes other shaping.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Puguglybonehead

At this point I'm switching to building something for guitar. (and maybe vocals) Going to put the TDA2003 board to good use, I hope.