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Author Topic: Help with talkbox internal amp?  (Read 8632 times)

RasmusR

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Help with talkbox internal amp?
« on: March 17, 2007, 09:58:01 AM »
Hi, I'm new to this forum, and new to DIY too, so try and bear with me.
So basically I am building a talkbox which will be like the Rocktron Banshee, it will have an internal small amp built into it along with a horn driver so I can put it in my pedal chain between guitar and amp (normally a talkbox goes between your head and cab). I have to build a small amp just enough to drive the horn driver effectively. I think it should be something around 5 watts or so, but would less than that work? What's the wattage rating for the ruby amp thats on runoffgroove.com? Would that work? I would run all the pedals I have before the talkbox, including overdrive pedal, so I dont really need a gain control and that jazz because I only need the clean. I am very new to electronics and some help would be really appreciated. Just ask me if something is left unclear in my post.

joecool85

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Re: Help with talkbox internal amp?
« Reply #1 on: March 17, 2007, 10:06:10 AM »
The ruby uses two lm386 chips to bring 1watt of power total.  With the proper horn driver it *could* be loud enough.  I would recommend a more powerful chip though, maybe something along the lines of a lm1875 (depending on voltage applied it can be up to 30watts RMS, or as low as 14 or something.)
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RasmusR

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Re: Help with talkbox internal amp?
« Reply #2 on: March 17, 2007, 10:10:25 AM »
Thanks. So instead of the two LM386 chips, I use two LM1875? Would i have to make any other changes to the layout?

syndromet

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Re: Help with talkbox internal amp?
« Reply #3 on: March 17, 2007, 01:01:25 PM »
Welcome to the forum! 8)
I would disagree with Joe here. First of all, I think the Ruby or little gem should be powerfull enough to drive a horn driver. A talkbox doesn't need a lot of volume, so I belive a lm386 based design should do it. I you have the driver and tube allready, I suggest you build the ruby and try it. If it doesn't work you can box up the ruby, and have a lm386 based desgn should do it. I you have the driver and tube allready, I suggest you build the ruby and try it. If it doesn't work you can box up the ruby, and have a very good pratice amp.

If the lm386 amp won't cut it, I think you should look for other designs than the lm1875 chip. This chip require a bipolar PS, wich means you can't run it off a regular wall wart or a battery. You would need an internal transformer too, and this would make the talkbox fairly big. I would suggest you look into someting like the tda2003, wich works fine on 12v DC. www.generalguitargadgets.com have a layout for a tda2003 amp, and I belive you'll find one in the schematic section of this site too.

I'we been planing to try somehing like this myself, but haven't find a usefull midrange driver yet. I have even bought the tube. :tu: Let us know how things turn out.

joecool85

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Re: Help with talkbox internal amp?
« Reply #4 on: March 17, 2007, 01:11:27 PM »
One LM1875 would be all you would need, I recommended it because depending on what he can find for a horn driver, he won't get enough volume out of the LM386 setup.  HOWEVER, I would definetly recommend trying the Ruby first.  Just find a good driver.  Also, for stompbox use a Ruby is better because as syndromet said, you can run it on 9v, no bipolar PSU to deal with and whatnot.
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syndromet

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Re: Help with talkbox internal amp?
« Reply #5 on: March 17, 2007, 05:36:16 PM »
One LM1875 would be all you would need, I recommended it because depending on what he can find for a horn driver, he won't get enough volume out of the LM386 setup.  HOWEVER, I would definetly recommend trying the Ruby first.  Just find a good driver.  Also, for stompbox use a Ruby is better because as syndromet said, you can run it on 9v, no bipolar PSU to deal with and whatnot.
That is why I suggested the TDA2003, as it's a very small circuit, can run of a 12v wall wart and don't need bipolar PSU. It doesn't sound as good and get as loud as a LM1875, but for a talk box it should be more than enough. The Lm1875 is a far better chip, but I thinkfor this purpose it overqualifies, and make the box harder to build than necessary.

joecool85

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Re: Help with talkbox internal amp?
« Reply #6 on: March 17, 2007, 06:28:48 PM »
I can vouch for TDA2003s not sounding so good, but it should get the job done.
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RasmusR

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Re: Help with talkbox internal amp?
« Reply #7 on: March 18, 2007, 09:37:18 AM »
Thanks guys,
I think I will try and build the Ruby with the LM386. Joe, you say I need two of the chips, but on the http://www.runoffgroove.com/ruby.html<<schematic there is only one chip... Am I missing something? I probably am, like I said, I'm new to this so yeah... So basically, I would connect the horn driver to the "output" on the diagram of this http://www.runoffgroove.com/ruby-perf.png? The output would lead the signal to the driver and amplify it, am I correct? On that same diagram, the "in" is where I plug the jack from guitar, eh? All this would run on 9Volts? If the chip can't handle the job properly, is there some other chip that would put out a little more watts that
still runs on 9volts? 9volts because I am powering my other pedals with a daisychain system anyway, and I have no idea how I would do with any of the internal transformer jazz...
Are there any alternatives for the Ruby amp, like the Little Gem/Smokey that would put out more power, and still run on 9volts?

Thanks for your help guys.

syndromet

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Re: Help with talkbox internal amp?
« Reply #8 on: March 18, 2007, 05:50:14 PM »
You're right, the ruby uses only one chip. You should look at the little gem mk2, wich is a 386 based design with two chips. If the little gem won't power the driver, you could, as mentioned before,use the tda2003 an supply it with a 12v wall wart that you use only for this effect. Most amplifier chips use a lot more power than your regular stompbox, so even if you find a design that could run off 9v I would suggest you use a wall wart for the talkbox alone. this, ofcource, depends on the power consumption of the amp, the mA rating on the wall wart you use in your daisy chain and how many and what kind of effects you have hooked up to it.
« Last Edit: March 19, 2007, 02:13:45 AM by syndromet »

joecool85

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Re: Help with talkbox internal amp?
« Reply #9 on: March 18, 2007, 07:35:01 PM »
Oops, sorry to be misleading.  You are right, the Ruby uses a single LM386, I was thinking the Little Gem MKII as suggested by Syndromet.  I think that would be a better circuit for what you are thinking of doing.
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RasmusR

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Re: Help with talkbox internal amp?
« Reply #10 on: March 19, 2007, 03:15:15 PM »
Ok thanks. I shall figure out the parts, and go buy them tomorrow from a nearby electronic store then. I probably will later need to ask some help about wiring the Little Gem up with the rest of the talkbox parts, horn driver, inputs, outputs, grounds, status LED, and powering (I know most of it[just to make sure]):D Thanks for your help guys.