Monday, 9 June 2014

Tiny Giant Amp

Requested by a few people on the forum, this is a mini amp circuit by Taylor Livingston with a bit more ooomph than the others on here, giving 20 watts into a 4 ohm speaker, or 12 watts into an 8 ohm.

Designed to run off a laptop power supply which I'm sure we all have hanging around the house from old broken laptops, with a LM338T taking that down to a regulated 11.6V to supply the opamp and amplifier.  The pins of the TDA7240A will need offsetting slightly so it is suitable for vero, but it can be done easily enough, as checked by Lazy Swamis on the forum.

Details of the project can be found here, and there is plenty of discussion to read through if you want to at diystompboxes.

Short clip of the amp in use






Posted by at 16:18
Tags: , ,

48 comments:

  1. Unknown9 June 2014 at 16:58

    Hi all.
    In a voltage doubler is a max1044scpa good to use in place of a 7660s anytime?
    dale

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    Replies
    1. IvIark9 June 2014 at 17:02

      The MAX1044 is rated for a maximum 10V supply, the ICL7660S can take up to 12V. Apart from that it would be fine, personally I prefer the peace of mind you get from the extra capacity from the ICL7660S, and they're also much cheaper.

      You can't use them in this though, it will be too much current for them.

      Delete
    2. Unknown9 June 2014 at 18:09

      I agree.
      Tayda here I come.
      jeff

      Delete
    3. Unknown9 June 2014 at 18:11

      Thanks.
      I am not building this one.
      I know, that to get your attention quickly, I go to the most recent post.....hee hee hee.
      jeff

      Delete
  2. Unknown9 June 2014 at 18:40

    Hi all ...Struggling to track down the TDA7240A. any alternatives? ...pref from farnell/cpc

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  3. boratto9 June 2014 at 18:44

    any chance on a 9v power supply version?

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    Replies
    1. IvIark9 June 2014 at 18:58

      No, the amp needs a higher voltage

      Delete
    2. Ark Angel HFB9 June 2014 at 19:48

      Could you use a charge pump before... maybe double the 9v to 18v then regulate down?

      Delete
    3. IvIark9 June 2014 at 20:03

      No the charge pump can't provide enough current

      Delete
    4. boratto9 June 2014 at 20:03

      maybe a tripler charge pump, than go back to 20v.

      Delete
  4. Beaker10 June 2014 at 00:12

    Nice one! Ordered the parts for this this morning. I'm thinking of putting this into a small hi-fi enclosure, along with a Rump Roast and a Schaller trem. Can't wait to get building.

    I would urge EVERYONE building this to FULLY READ ALL THE DOCUMENTATION on the link above. That stuff about grounding and isolating the heat sinks is critical - you don't want to risk electrocution!

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    Replies
    1. vince10 June 2014 at 01:05

      How could a person Electrocute them self's at such a low voltage anyhow?















      Vince

      Delete
    2. Unknown10 June 2014 at 04:21

      I thought the danger was not electrocution, but rather burning up components. It's not all that much current really.
      Heat sinks probably never saved anyone from lightning poisoning.

      Delete
    3. Beaker10 June 2014 at 10:42

      Erm, sorry guys - Arse of the month award goes to me - (huge round of applause).

      That was really stupid of me. Swamis right, the bit about grounding relates to burning out your components, not electrocution.

      Must have been too tired last night. I'm going to sit in the stupid corner now...

      Delete
  5. Unknown10 June 2014 at 04:00

    got everything ordered or arrived. 1590A friendly for sure.
    I think I'll just zip tie the Tiny Giant on top of the reverb tank in my old vibrolux.
    The next time the old girl starts acting up in the middle of the show, I'll let her rest a bit.
    Thanks a heap lvlark!

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  6. Doron Barness10 June 2014 at 04:47

    verified?

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  7. Alex S.10 June 2014 at 10:41

    Am I right in thinking I could put any preamp (is one of ROG's JFET emulations) before the volume control instead of the TL072 pre?

    If that's the case I think many people would enjoy a very layout for the post volume amp section only (which I assume is as per the TDA7240A data sheet?) to try some options out, tweak or create multiple pres monster mini amps *wink wink* :)

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  8. 12314 June 2014 at 18:00

    Hi!Can I replace LM338 by IP338 ?

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  9. Kinski19 June 2014 at 02:57

    Here is a mod to just use a 12v power supply, and get rid of the regulator. Could I just follow these same instructions when using your layout? Omit the 1K and 120R resistors, and connect the 2 legs of the regulator pads?

    http://i1160.photobucket.com/albums/q485/jdansti/0AB0651D-D4B0-46A7-A5F8-BDE5DD767627-12822-00000C36B2650DE0.jpg

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    Replies
    1. Unknown15 September 2015 at 22:17

      Good idea. 12 vc source is cheaper than the 19,5v
      Have made this in practice?? worked fine??

      Delete
  10. Kinski26 June 2014 at 14:02

    Anyone have any success building this yet? I'm still waiting on some parts from China. Should be here by next week hopefully.

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  11. vigilante3974 July 2014 at 03:29

    I just got this all put together and am having trouble getting it working :-/ A few questions:

    1) What is the proper pinout of the amplifier? Numbering 1-7 isn't very informative, though I'm not entirely sure that's my problem.
    2) How am I supposed to connect the amplifier and regulator to a heatsink if they are sideways in the middle of the circuit?
    3) How are the speaker 1 and 2 supposed to be hooked up? To those correspond to - and + terminals of a speaker? Please clarify.
    4) Related: is speaker - allowed to be grounded? I would like to turn it into a 1/4" output so I can drive a cab with it like a head.
    5) Will someone please just take a picture of a completed build so I can double check mine? :-/

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    Replies
    1. Beaker4 July 2014 at 13:45

      1) Pinout:

      1
      2
      3
      4
      5
      6
      7

      2) I used ribbon cable to form "flying leads" to do this.

      3) Yes, 1 to + and 2 to - (though it does not matter if you reverse them).

      4) NO - DO NOT GROUND the speaker jack. Use a plastic case jack socket or spacer sleeve to isolate to jack from the enclosure. (Read the PDF linked at the top of this page.)

      5) I will photograph my board when I've finished it, and put it on the forum post, (also linked at the top of this page).

      Delete
  12. Kinski17 July 2014 at 19:16

    Crud. I don't have any 2.2ohm resistors. Closest I have is 7.5ohm. How important are those values?

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  13. Bohemian H17 July 2014 at 20:45

    If you put 2 of those 7.5 ohm resistors together PARALLEL you would get 3.75 ohm which is a lot closer.

    Three 75.5 ohm resistors in PARALLEL would get you down to 2.5 ohm.

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    Replies
    1. Bohemian H18 July 2014 at 10:23

      That last sentence should read "7.5" not "75.5"

      Delete
    2. IvIark18 July 2014 at 10:42

      I've got a keyboard like that :o)

      Delete
  14. Zach30 July 2014 at 05:23

    anyone get this one working? i was thinking that it would be awesome to put the preamp section for whatever amp you really want in front of this and you can essentially have a mini version. like putting an orange preamp in front could give you a mini 20watt orange that can fit in a guitar case.

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  15. Andy Miller8 August 2014 at 01:55

    I've got this layout working. A few words to the wise. .. . First, verify that your power supply can provide 4A or better. I neglected to check that and tried to make it work with a 2.6A supply and it just won't make any useful sounds that way. If you've got a big enough laptop supply laying around, you're in luck. If not, you're going to have to spend some money to power this thing. Next, you have to keep your signal wires away from your power wires away from your speaker wires, or you will experience a lot of noisy, crosstalky shit. Finally - get your heat sinks squared away before you start trying to power this up/troubleshoot it, lest you cook your ICs before you ever get it working.

    Thanks for the layout lvlark, so many fun projects. . . .

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    Replies
    1. Unknown8 August 2014 at 02:27

      how did you fit the heat sinks inside the layout ?
      i tried firing it up without the heat sinks...
      got kind of a floppy sound then a high pitch squeal ...
      the guitar sound is coming thru thowe with allot of distortion and low volume with allot of heat.

      Delete
    2. Andy Miller8 August 2014 at 02:38

      I could only fit a heat sink onto one of the two ICs in this layout without the heatsinks touching, so I wired the voltage regulator offboard.

      Delete
    3. IvIark8 August 2014 at 10:03

      Awesome, thanks for verifying Andy

      Delete
    4. Unknown8 August 2014 at 22:11

      ok so i installed the heat sinks and im still experiencing issues.
      im getting some floppy sound at about 60 hz frequency. it sounds similar to driving in a high speed with one of the windows in the back open.
      the guitar sounds very weak and distorted and still it goes to a high pitch squeal after a few seconds...
      you know what can explain this ?
      i'm running it thru a 3.17ohm 8 inch speaker.

      btw are there suitable sockets for ics like those in this project ?

      Delete
    5. Unknown9 August 2014 at 15:38

      https://dl.dropboxusercontent.com/u/35159092/20140809_173008.jpg
      https://www.dropbox.com/s/89q4nwu3s1ish67/20140809_173016.jpg
      i have provided with a few pics...
      can this problem be related to heat dissipation ?
      maybe my heat sinks our not sufficient ? i noticed that the ics our getting really hot while the metal boards i use are not heating up so much ?

      Delete
  16. Insulator17 August 2014 at 07:38

    I have a working layout that positions the 2 chips at one end of the board for heatsinking purposes. See here for details:
    http://www.diystompboxes.com/smfforum/index.php?topic=89687.msg983965#msg983965

    ReplyDelete
  17. Andy Miller19 August 2014 at 13:09

    Ugh. I started having problems with my build, cutting out plus intermittent if you nudged the power amp IC. During troubleshooting I broke one of the leads off the TDA7240 I got from China on ebay. I have since broken the leads on 2 more of them trying to replace it. I suspect I got some crappy ICs, they're barely rugged enough to install in a build. Be careful. Not sure where to look for better ones. Futurlec has them, not sure whether to expect theirs to be any different.

    ReplyDelete
  18. Kinski19 August 2014 at 13:29

    I'm doing something wrong here. Immediately after powering up the TDA7240 went up in smoke. I mean a TON of smoke.

    I did try to bypass the regulator and just use a 12v power supply. I read that to do this you can just omit the 1K and 120R resistors, and connect the I and O of the regulator? But that was for the PCB. Did I do something wrong doing with this vero layout?

    ReplyDelete
  19. Andy Miller20 August 2014 at 01:38

    Kinski - make sure you don't have something shorted to ground that's not supposed to be - like a wrong connection/solder bridge/missing cut at the board, or a metal bodied speaker jack connecting to ground, for example.

    ReplyDelete
  20. Unknown24 November 2014 at 11:22

    hey all,
    i apologize in advance for my english.
    i have built this little beauty for the second time now and still no success.
    the thing works in very very low volume. but when i try to turn the volume up a bit or sturm a few strings together i get this repeating pop sound.

    i build this with a slightly larger vero layout to accommodate the heat sinks.
    i have used monolithic capacitor for the 1u values.
    i tried looking for bridges mis matched components and such with no luck
    i replaced the amp chip the power regulator the ic and the power supply and got the same results with all of them.

    https://www.dropbox.com/sh/uq6n3x2f4u4z6t9/AAAk1LRsrtmeOfIAZZnpk2Ava?dl=0

    could it be one of the capacitors ?
    any ideas what could have gone wrong ?

    ReplyDelete
  21. Friedrich6 May 2015 at 12:57

    Requested by a few people on the forum, this is a mini amp circuit by Taylor Livingston with a bit more ooomph than the others on here, giving ... mguitaramp.blogspot.com

    ReplyDelete
  22. Arkham18 September 2017 at 11:01

    Hi, can someone tell me which heat sinks I need for this project ?
    Is there anything in this list that would do the trick ? https://www.musikding.de/navi.php?qs=heat+sink
    Thanks

    ReplyDelete
  23. Piotr Kuzemczak15 December 2017 at 11:50

    Great amp. Works fantastic with the active baxandall tonestack.
    Regulator and amplifier wired offboard.

    ReplyDelete
  24. Sevrien16 February 2020 at 10:54

    This comment has been removed by the author.

    ReplyDelete
  25. Sevrien16 February 2020 at 12:50

    This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Sveto38910 March 2020 at 23:59

      the best way to put fxloop is before volume pot or after pin 2 of volume pot... if you are doing only amp
      what i have done is i put ROG Tonemender in front of the amp and i put fx loop between tonemender and tiny giant amp
      also i had some trouble with loud noises after half way up on volume so i put a speaker simulator and problem solved not best solution but works
      so if u run it on 12v dc be prepaired to make good trouble shoooooting
      for the TDA7240 i cant help u much i found it in local electronic store

      Delete
  26. Sevrien10 April 2022 at 15:40

    Hello, can someone please verify if my ideas are correct?

    Variable gain: replace the 220K resistor wit a 250K pot?

    preamp bypass: a switch that toggles the input signal between the standard input and pin 3 of the Volume pot?

    Any suggestions to make it suitable for bass guitar?
    I'm looking for a clean sound, maybe some breakup on high gain.

    Will a switching power supply work? or wil it produce too much noise? I'd like to build a small practice combo that is power straight of the net.

    ReplyDelete

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