Building the Tiny Giant amp

[garcho]

@Ark Angel

buy the kit, you'll be happy you did when you're playing through it 15 minutes after getting it in the mail

[Ark Angel HFB]

Ok just ordered it...

To be frank I'm halfway flirting with the idea of become a part time custom order pedal maker / tube maker...

I'm hesitant even mentioning this as it almost feels like people who do this are frowned upon on these forums.

But I think that comes one from the fact most people here know how cheap it is to make a pedal... and how over priced everything is that companies sell.

It is one reason why I just bought the amp I did is because one, I can learn how to make it first hand... and second... he didn't charge $30 to $40 for the kit like most would have... The fact he didn't try and run the price up on people is a show of both character and goodwill and is a sign of person who deserves to be paid for their quality work.

/mini-rant.

[Taylor]

Nobody has any problem with you (or anyone) building things for sale. There are many people on this forum who make some or all of their living from building effects or amps. What many people do object to, is when people come here, take DIY projects, and then sell them without asking permission or compensating the designer - or, in general, cashing in on other people's work. People also object to those who want others to do their homework for them. This is true in any discipline.

I started to write some "personal advice" on a custom electronics business, but it was going to be too long and boring. Short version: you might find that you spend more time emailing about what the person wants than it takes to build a pedal. IME you might find yourself making much less than minimum wage when you do the real math.

Nobody's going to object to you becoming a big star in the pedal biz. But I suggest that you forget the dollar signs for now, build a ton of things for your friends for free, to their exact specs, then reassess once you have a better idea of what goes into it. If you think most pedals are overpriced, you may have a lot to learn about business.

[Ark Angel HFB]

No my main thought has more to do that if you make a product for $50 you should's charge over $150.

I know it sounds odd but I'd rather sell twice as many at half the price so more people can have good effects and amps and what not. This is coming from a Former guitar teacher who had the displeasure of seeing people(mostly kids) come in with a lot of excitement, and then be held back by bad gear. It was such a horrible feeling looking at a kids/people who had practiced hard and were doing a chords perfectly but due to cheap instruments or amps... were sounding really bad. Actually seeing enthusiasm die in a person is a completely crap.

I gave lesson for cheap, around $10 to $15 hour, and if I make pedals I'm sell them for cheap.

Don't get me wrong I like making money... but I don't think I could live with myself if I started just another company that made good stuff and then kept it outside of people just starting out by charging more than it is really(massively subjective word) worth.

anyway to stop derailing this thread.

I've been looking at a few PS for this little amp and have a few I'd like to get your opinion on. I specifically found some that seem to have a good supply behind them so that if anyone else wants one of these there should be plenty for a good long time.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190426611359+&item=190426611359&lgeo=1&vectorid=229466#ht_3219wt_1185

http://www.amazon.com/PA3048U-1ACA-PA3282U-1ACA-PA3282U-2ACA-pa3260u-1aca-Satellite/dp/B001MQ35EY/ref=sr_1_12?s=pc&ie=UTF8&qid=1333599515&sr=1-12

[Taylor]

The second one is better since it is 15v. Technically the 12v would be fine but you'd want to bypass the voltage regulator on the board. For those just getting started, who don't want to mess with modifying things, I'd recommend the 15v one.

[Ark Angel HFB]

The second one is better since it is 15v. Technically the 12v would be fine but you'd want to bypass the voltage regulator on the board. For those just getting started, who don't want to mess with modifying things, I'd recommend the 15v one.

Well crap a duck... I could when I was linking them that they were both 15v. XD

[Ark Angel HFB]

was looking things over and I think a cool mod / adition to this that wouldn't be to much trouble would be an effects loop... maybe even get fancy with some kinda foot switch option or something... I do so love being fancy. 

It would be added just before pin 3 of the TDA7240A, or am I missing something.

[garcho]

Maybe try building one of runoffgroove.com's amp-turned-stompboxes as a pre for your TG, then no need for an effects loop, and you'll get some real guitar amp-y tone, too.

[Colonel Angus]

Question RE: Tiny Giant P/S - I haven't looked at the supplies that others are buying, but I rounded up a couple laptop P/S last night and they all had what appears to 4.5mm jacks. Has anyone sourced a P/S that fits in 4mm or is everyone just buying the 4.5mm Kobiconn?

[Taylor]

For one of mine I cut off the supply's plug and wired in a regular 2.1mm (internal dimension) plug for interfacing with a standard (for pedal use) 9v jack.

However, I feel that this is probably not best practice, since you now have multiple power supplies which are electronically incompatible (your pedal supply and your amp supply) but which can physically be interchanged. Potential for bad things. Probably smarter is to buy some unrelated plug and jack that you would never use for anything else. That way your amp supply can't plug into anything into which it shouldn't.

Depending on space you can also simply wire the supply directly to the amp PCB if you are mounting them together inside an enclosure.

[arma61]

Hey guys thx for help...

T I don't see anything obviously wrong in your voltages, so my guess is that there is just an open circuit somewhere in your audio path. I would recommend audio probing to see where the signal is getting stopped.

That's good to know, this mean I didn't mess up with the important components (btw I hat those resistor    having a cheap&old multimeter it's quite hard to take their value!!!).

I will have a go with the audio probe in the next days and report, quite sure, being the voltages right, it's something stupid... so better I leave it sitting there for a while...........

Thanks again

Ciao

Hi there

happy to report I'm now an owner of 2 working TGAs !!     

There problem was, most probably, related to the stuff I used to test it, signal coming from an old walkman powered by a not-so-well-filtered wallwart... (bored to keep on changing batteries 'cause I leave it on everytime    ), so when I connect the right speaker and the guitar it works as it's supposed to!!!

Thanks again m8s for help and again to Taylor for this fab little amp.

Have a nice day!!!

Ciao

[Taylor]

Glad to hear it Armando!

[Colonel Angus]

I guess I meant 2/2.5 mm not 4/4.5. Anywho, you seemed to take my meaning and answered my question. Thanks Taylor!

[Taylor]

No, you might well be right about that - they have an internal dimension and an external dimension. I always forget the external dim of the standard pedal jack, but I'm sure it is somewhere in the range of 4 or 5mm.

[Ark Angel HFB]

Ok so here are some things to consider / help me out with... 1 you might want to go ahead and give a heads up about the kit not including the 10k pot... just saying I was getting ready to build this it tonight then had to go aaa crap... I don't have a part. it isn't a big deal. they are $1 off ebay with free shipping so it is on it's way... but it was a bit of a disappointment to have to wait. XD

You may want to redesign or maybe just leave a bit more room so that the 1k resistor is swapped for a 1k trim pot with a 500ohm resistor in series after it. This would allow people to dial in the volts/power output they want as well as protect against it going over the 1.5k limit you suggested.

Just saying these are two changes that might make this an even better product. ^_^

In the same vein as the second thing mentioned above I'm planing on combining this with a ValveMaster which I would like to run at 12.5vDC.

I'm using a 15vDC 4A Power supply so...
A. what value should the 1k resistor change to to give me a steady 12.5vDC.
or
B. Simply tell me how to do the calculation and I will do it myself so it is not like I'm just asking for all the answers in the world. XD

[Taylor]

Ok so here are some things to consider / help me out with... 1 you might want to go ahead and give a heads up about the kit not including the 10k pot... just saying I was getting ready to build this it tonight then had to go aaa crap... I don't have a part. it isn't a big deal. they are $1 off ebay with free shipping so it is on it's way... but it was a bit of a disappointment to have to wait. XD

Hmm, ok, this is tricky because I do state precisely everything that comes in the kit, but not what doesn't come in the kit. The reason it doesn't come with the pot is that there a million different types and every person will want a different one (9mm for 1590a builds, 25mm for heavy duty amp guys/solid shaft, knurled shaft...). This is also why the kit doesn't come with an enclosure, knob, heat sinks, etc. But I definitely see how that could be confusing and a little annoying for somebody who doesn't know quite what they need. I will think about how to solve this.

I'm using a 15vDC 4A Power supply so...
A. what value should the 1k resistor change to to give me a steady 12.5vDC.
or
B. Simply tell me how to do the calculation and I will do it myself so it is not like I'm just asking for all the answers in the world. XD

No problem asking questions, however now is a good time to learn that about datasheets!  Every part in the world has a datasheet, and it knows more about the part than even the legends on this forum ever could. So the regulator is called LM338T. When you need a datasheet, you can usually just google the part number and hit the first PDF you see.

http://www.ti.com/lit/ds/symlink/lm138.pdf

The relevant equation is on page 7. What I have done on a build before is to solder in a pot or trimpot, find the voltage I want, then sub in the resistor of that value. To me this is better than putting a trimpot in the amp - trimpots get bumped, or you might forget what it does, etc. so to me a critical function like this, which does not need to be tweaked later on, is better as a fixed value.

[Ark Angel HFB]

Ok so here are some things to consider / help me out with... 1 you might want to go ahead and give a heads up about the kit not including the 10k pot... just saying I was getting ready to build this it tonight then had to go aaa crap... I don't have a part. it isn't a big deal. they are $1 off ebay with free shipping so it is on it's way... but it was a bit of a disappointment to have to wait. XD

Hmm, ok, this is tricky because I do state precisely everything that comes in the kit, but not what doesn't come in the kit. The reason it doesn't come with the pot is that there a million different types and every person will want a different one (9mm for 1590a builds, 25mm for heavy duty amp guys/solid shaft, knurled shaft...). This is also why the kit doesn't come with an enclosure, knob, heat sinks, etc. But I definitely see how that could be confusing and a little annoying for somebody who doesn't know quite what they need. I will think about how to solve this.

I'm using a 15vDC 4A Power supply so...
A. what value should the 1k resistor change to to give me a steady 12.5vDC.
or
B. Simply tell me how to do the calculation and I will do it myself so it is not like I'm just asking for all the answers in the world. XD

No problem asking questions, however now is a good time to learn that about datasheets!   Every part in the world has a datasheet, and it knows more about the part than even the legends on this forum ever could. So the regulator is called LM338T. When you need a datasheet, you can usually just google the part number and hit the first PDF you see.

http://www.ti.com/lit/ds/symlink/lm138.pdf

The relevant equation is on page 7. What I have done on a build before is to solder in a pot or trimpot, find the voltage I want, then sub in the resistor of that value. To me this is better than putting a trimpot in the amp - trimpots get bumped, or you might forget what it does, etc. so to me a critical function like this, which does not need to be tweaked later on, is better as a fixed value.

Thanks for the help... I completely get what you are saying and I wasn't saying that you should have included a pot... as like you said everyone has their own type of pots that they like... someone might want to get a push/pull and have it act as a switch. What I was suggesting was to find an place to state that a 10k pot is needed. it wouldn't hurt anything to treat it the was as your international shipping message.

heck you could probably even have a quick three line bit about were to buy the for cheap and what to look for. People find actions like this reassuring... although you time might be mostly wasted as most here know how to buy a pot and what to look for. ^_^

On a related side note I could have sworn I was very good at math... but now my brain hurts and I feel dizzy. T_T... how the hell do I find out Vout... do I just stick in the number I want it to be then solve for that number. T_T...

[zuk16l]

I can't find any female jacks for my 15v power supply.  Can I just rewire the male from a 6mm to a 5.1 which are available locally.  I guess I'm being impatient.

[Colonel Angus]

Look up a few posts, I had a similar question. The answer is yes, you can but then you run the risk of using your specialized power supply with a regular pedal, which could cause problems.

[guitarplayer83]

Built the Tiny Giant today and plugged it up and the TDA7240A melted. Any idea what is wrong.  I ordered everything as a kit.  I am using this power supply http://www.ebay.com/itm/270860174266 Thanks for the help