collapse

Author Topic: TDA2003 based Guitar Amp  (Read 25496 times)

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
TDA2003 based Guitar Amp
« on: January 19, 2008, 01:55:11 AM »
Good Day All!

Attached is a schematic of the amplifier I made I call the "Bug Eyed Monster" because the grills from the Roadmaster 5x7 speakers I bought at Wal-Mart give it that appearance!

About 8 to 10 watts RMS capable per speaker in this configuration.   Again, Mouser.com for most parts, I build the cabinets for these from scrap lumber and use hardware store handles and rubber furniture feet for the amplifer feet.  When I get my digital camera operational, I'll post some pictures of these amplifers I am providing schematics for - They are in use!

Again, the input is from "The Ruby" by runoffgroove.com, and the P.A. portions are from the datasheets for the chips, with my own "tweeks" added.  "Astro-Peke Music" is the "pen name" I use if I am building an amplifier for someone else, but I folded it as a small business - not enough time with my full time job to give a side business proper care!

To repeat from my first post -  I like high impedance inputs, and to keep hum and such down, you need to make certain and use a switched input jack that shorts the input to ground when there is no plug inserted.  (personal preference, in all my designs the input impedance is determined by the input resistor pair - feel free to modify as you see fit)

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #1 on: January 23, 2008, 10:17:00 PM »
Front and back pics of the Bug Eyed Monster!

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #2 on: January 23, 2008, 10:21:28 PM »
The "innards" of the Bug Eyed Monster.  Yep, 5x7 Roadmaster speakers from Waly World (20.00 for the pair), scavenged transformer and computer grade filter capacitors.  In the second pic a closeup of the "buisiness end" of the boards - note the HOT GLUE board mounting.  (Glue Guns - not just for crafties anymore).  The heat sinks on the TDA2003 chips are anodized aluminum.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3151
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: TDA2003 based Guitar Amp
« Reply #3 on: January 24, 2008, 07:32:20 AM »
Why such giant caps on the power supply?  (The ones as tall as the transformer lol)
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #4 on: January 25, 2008, 06:38:11 AM »
Simple reason for the BIG caps - I got them FREE, and had the space in the case. 

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #5 on: February 19, 2008, 02:13:16 AM »
Attached is an improvement I made in the B.E.M.   Moving the injection point for a tape player/CD/external audio seems to work better in the new location. 8)

casiomax

  • SSGuitar Regular
  • ***
  • Posts: 27
  • Chip Points: 0
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #6 on: April 16, 2008, 07:36:53 AM »
i dont really understand electronics, but from what i see, the front stage was with a FET pre-amp, can i eliminate this, and use other pre-amp? or the FET stage is critical?

I have built the tda2003 stage, and put an 8ohm speaker on each output, plug it to my electric-acoustic guitar, it already made a loud sound.

the pre-amp that i was thinking is the Tonemender from runoffgroove.com

thanks.

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #7 on: April 16, 2008, 10:46:00 PM »
Casiomax,
Yes, you certainly can use a different preamp with this unit.  I used the FET as an impedance matching device only, to give me a higher "front end" impedance going into the amplifier.
I use this ampifier with both electric and acoustic (piezo pickup) guitars, and the EXTEREMELY high input impedance is a MUST for the piezo pickup.
The FET preamp section has NO gain to it, typical of a source follower circuit.  In fact, I have measured the output voltage at the high end of the Volume Pot and the voltage is approximately 90% of the input voltage.
The buffered output is simply an additional feature that I use to daisy chain amplifiers together. (or to go to a "house" system).
Good luck and good building!
 :tu:

casiomax

  • SSGuitar Regular
  • ***
  • Posts: 27
  • Chip Points: 0
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #8 on: April 30, 2008, 09:39:02 AM »
I succesfully build the amp, also the preamp using the tonemender. I try to plug my guitar directly to the amp, it produce great clean sound, but when i try to hook up the tone mender before the amp, withouth plugging in my guitar it produce noise sound and humming.

Is pre amp design prone to low frequency signal? like RF signal sometime giving oscilation or something?

teemuk

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 1073
  • Chip Points: 282
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #9 on: April 30, 2008, 10:28:46 AM »
Many amplifiers hum when their inputs are left "floating". You need to use a switching input jack that grounds the input when the cord is not plugged in.

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #10 on: April 30, 2008, 06:38:37 PM »
Casiomax,

Glad to hear you had a successful build.  I designed the amplifer to be squeeky clean in its original inception, and haven't tried putting any pedals other than my chorus in front of it.  The chorus pedal does NOT have a "shorting when unplugged" input to it and if I turn the amplifier on with only the chorus pedal plugged in and on, I also get HUMMMMM.

If you look at the third paragraph of the first post, you will see that I recommended a "shorting when unplugged" input jack to the amplifier.  Most commercial amplifiers (the good ones, anyway,) have this type of arrangement on the input to keep hum down when the guitar is not plugged in.

Teemuk has it right on the money!  I'm certain that the hum you hear is the high impedance input picking up the powerline frequency.

The noise should go away when the guitar is plugged in.  It is for this reason the "old timers" in the music scene recommend plugging in the guitar BEFORE turning on the amplifier - stops hum and "connection noise".

Hope you enjoy it! :tu:




casiomax

  • SSGuitar Regular
  • ***
  • Posts: 27
  • Chip Points: 0
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #11 on: April 30, 2008, 08:56:26 PM »
without the tonemender no noise coming out from the amp. when i plug my guitar a short hummm is normal. without the guitar attached to the pre-amp (tonemender) noise is coming out from the amp. my intention was to build a tonestack before the guitar. and yes, the guitar input was grounded when no jack is plugged.

I guess i just build a simple 3knobs tonestack with a transistor pre-amp, maybe this would solve my problem.

thank you all for the help, lets see how it goes.

casiomax

  • SSGuitar Regular
  • ***
  • Posts: 27
  • Chip Points: 0
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #12 on: May 01, 2008, 07:38:37 PM »
by the way, can I bridge the output from two TDA2003 into one 4ohm speaker?

n9voc

  • Elite SSGuitarist
  • *****
  • Posts: 102
  • Chip Points: 35
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #13 on: May 01, 2008, 10:08:38 PM »
RE: Bridging TDA2003

Indeed you can, take a look at the datasheet for the chip, some versions of it on the net have the bridge circuit included.

casiomax

  • SSGuitar Regular
  • ***
  • Posts: 27
  • Chip Points: 0
    • View Profile
Re: TDA2003 based Guitar Amp
« Reply #14 on: May 01, 2008, 11:27:59 PM »
hey, thanks again, i found the datasheet and i will try to bridge my 2xTDA2003 amp. Regarding to the tonemender i builted, maybe using TL072 was the problem, should change to a better low noise dual opamp.

Basically, I only need a preamp with tone control.

 

* User Controls

 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?

* Recent Posts

Another Randall RG100ES question by vidmachine
[May 22, 2019, 11:17:47 PM]


Peavey Stereo Chorus 212 by vidmachine
[May 21, 2019, 12:58:44 PM]


Crate gx900h by Basill
[May 21, 2019, 09:19:36 AM]


Heathkit TA16 by GlenF
[May 12, 2019, 10:33:44 PM]


Dual or Split supply Audio amps by phatt
[May 07, 2019, 05:11:13 AM]

* Sponsors