Building the Tiny Giant amp

[Keeb]

On that note, my laptop DC has something attached to the cord on the DC side (it's a small cylinder - smaller than a size C battery).  I have noticed this on multiple AC to DC converters on the DC side.  What is it?  I already cut the stock end off and soldered my power end, but I want to replace it.  Cutting it again will put me very close to this widget. 

A ferrite bead perhaps?

http://en.wikipedia.org/wiki/Ferrite_bead

[DocAmplify]

Yes.  It is so close to the end that I worry that I'll have to cut it off if I modify more, but it sounds like a useful addition to the power line. 

[bcalder]

So ... my amp is now 100%. I had labeled one of the NC jacks with a piece of masking tape, and part of it must have slipped between the switch & tip contacts, preventing it from completing the circuit without patching it. It's working great now.

[garcho]

Here's my Tiny Giant build. It sounds awesome even without a preamp. Taylor's PCB soldered together in about 10minutes. It's in a crappy faux train case with a Jensen Mod 10". Plenty of room left for my lonely, dusty spring reverb unit. I hope the speaker doesn't vibrate the unit too much. The box is light, so I'm sure it will, but I'm gonna try anyway.

           

[Taylor]

I like it. 

[DocAmplify]

This may speak to my total confusion here, but I've searched and can't find the answer. 

Does the Tiny Giant have a preamp and an amp section? 

My goal was to plug my guitar into the tiny giant and then go out to my cabinet. 

I notice that many of the effects pedals have amplifier sections (op amps or transistors).  If you use an overdrive or distortion could you consider this a preamp, or am I misunderstanding?

[garcho]

Personally, I would just build the Tiny Giant, plug your guitar in, play with it for a minute, and judge from there. Maybe like me, you'll find it sounds great the way it is. I don't mind schlepping pedals around, so it doesn't bother me that the circuit is bare-bones.

The TL072 is a preamp/buffer for the TDA.

Also, I would make CERTAIN everything passes the continuity test before trying it with your cab. Do you have a cheap speaker laying around?

I like it.  Cool

Thanks dude!

[DocAmplify]

Yes.  I tried it through an old car speaker, then through a TV sound system speaker, then my cab. 

If the TL072 is acting as the pre-amp, then am I correct in assuming that the only reason for another pre-amp would be for tone control (as opposed to actually boosting the signal). 

If that's the case, then would a cab simulator like the Condor (or Marshall modified Condor) serve the purpose of adjusting the tone quality?  Or would that make changes that then get further changed when it hits the actual cab?

I'm thinking about building a Condor cab sim modified with the Marshall dip so I can put my guitar directly into the mixing board, but if it could piggy back on the Tiny Giant on occasion, then I'm all for multi-tasking. 

[Taylor]

The TG does have a basic clean preamp at the beginning, so you can definitely plug your guitar straight into it. The only reason to add another preamp or pedal is to get a particular sound.

If you replace the 220k resistor with a 1m pot, then put anti-parallel diodes in parallel with the pot, you could have some variable TS-style distortion/overdrive. Adding some tone shaping after that would probably be preferable to most people, but it's all a matter of personal preference. Some people have posted their thoughts on adding tone stacks to the TG in this thread.

I would build the cab sim as a separate unit, because you won't generally need a cab sim when using an amp into a real cab. If you were going to record to a desk while also playing back through the TG and a cab, it would make most sense to split the signal with an active ABY or something, then run to the two devices.

[arma61]

Hi there

built a second one, for a new fun project.... while the first one worked the first time I've turned on, with this one I've problem..... I've no sound at the speaker, just noise, almost like when gnd is missing, there is sound there, I can hear it, but completely covered by the noise. I'va taken some voltage readings, here they are

PSU - 19.40
TL072
1 - 5.96
2 - 5.96
3 - 4.06
4 - 0
5 - 4.07 ?? on Taylor pdf it states 11.6!!
6 - 5.79
7 - 5.99
8 - 11.82

LM338 facing from the front
10.58 11.83 19.39

TDA facing from the front
1st row of 3 pins
11.82 - 0 - 5.38
2nd row of 5 pins
5.59 - 5.55 - 4.83 - 5.56

I've changed already 6/8 TL072 with the same results.

Compared this board with the working one... everything seems to look the same

Pitcture of the board
http://i256.photobucket.com/albums/hh174/arma61/SNC00019.jpg


Any idea on what could be wrong ? there's no way I can get more than 4.7V at pin 5, it this the problem ??


Thank for help m8s!!!
Ciao

Armando

[Keeb]

PSU - 19.40
TL072
1 - 5.96
2 - 5.96
3 - 4.06
4 - 0
5 - 4.07 ?? on Taylor pdf it states 11.6!!
6 - 5.79
7 - 5.99
8 - 11.82

Any idea on what could be wrong ? there's no way I can get more than 4.7V at pin 5, it this the problem ??


Thank for help m8s!!!
Ciao

Armando

I get the same voltages and mine works.
Both pin 3 and 5 are the non-inverting inputs. If you look on the schematic pin 3 is fed 11.6V through a voltage divider that reduces the voltage by half so your pin 3 is correct.
If you look on the PCB, pin 3 and pin 5 are connected so they should read the same.
I can't help tell you what's wrong but I don't think your problem lies within the tl072.


The PDF might be confusing. I think the TL072 side named U1A in the schematic is pin 5, 6 and 7 (pin 8 gets 11.6V and 4 goes to ground). I base this on the fact that by looking at the PCB it looks as though pin 7 is connected to pin 6 through the 220k resistor and pin 1 and 2 are tied together (like shown in the part named U1B).

Maybe Taylor can shed some light on the subject.

[Taylor]

Pin 5 is actually connected to pin 3 and therefore driven by the input signal and biased to the center of the power supply. That opamp is not being used and this is just a way to hold it near the center of the supply to avoid drawing a lot of current.

So, that's a mistake in the schematic. There was an error in the voltages at one point, which I corrected, but it looks like in correcting that I created a new error. In other words, there should NOT be 11.6 at pin 5.

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.

[Keeb]

Pin 5 is actually connected to pin 3 and therefore driven by the input signal and biased to the center of the power supply. That opamp is not being used and this is just a way to hold it near the center of the supply to avoid drawing a lot of current.

So, that's a mistake in the schematic. There was an error in the voltages at one point, which I corrected, but it looks like in correcting that I created a new error. In other words, there should NOT be 11.6 at pin 5.

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.

Sometimes, I find it hard to know when there is an error somewhere or wether it's just my lack of knowledge keeping me from understanding things. But just for my own understanding, am I correct in thinking that the U1A part is pins 5, 6 and 7 making the U1B pins 1, 2 and 3?
I'm used to thinking of opamps as a record, "A" being the first side (1,2,3,4) and "B" being the second side. That's why I'm asking.

I would also like to take this oppertunity to thank you Taylor. I have built two of these using your kit and they have both been great. Much appreciated!

[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

[Ark Angel HFB]

Hey guys I'm just breaking into this whole pedal thing and I wanted to run some ideas by you guys and see if you could help me make them happen.

We all know that tubes being driven sound great. And that ss amps have awesome cleans but if driven to hard can make a really bad sound.

What I wanted to know is...

would it be possible to use a tube circuit like the "valve-master" and wire it up to this SS amp with some kinda limiter/buffer between them so that no mater what the settings on the valve-master were, the "Little Giant" was feed a relatively lower output signal level.

This way The valve part of this new amp could be driven as hard as you want, getting all the goodness that tubes can offer, while the SS section didn't clip and was allowed to push out a good signal inside it's normal range.

Would this be as simple as a slight compression circuit or just setting the Valve-Master up as if it volume pot was turned much lower(like around unity gain), and have the only control from it be the gain knob?

Would this work? I mean if it did it might just be the greatest Tube/SS hybrid amp you could make for around $70USD

[Somicide]

Hey guys I'm just breaking into this whole pedal thing and I wanted to run some ideas by you guys and see if you could help me make them happen.
We all know that tubes being driven sound great. And that ss amps have awesome cleans but if driven to hard can make a really bad sound.
What I wanted to know is...
would it be possible to use a tube circuit like the "valve-master" and wire it up to this SS amp with some kinda limiter/buffer between them so that no mater what the settings on the valve-master were, the "Little Giant" was feed a relatively lower output signal level.
This way The valve part of this new amp could be driven as hard as you want, getting all the goodness that tubes can offer, while the SS section didn't clip and was allowed to push out a good signal inside it's normal range.
Would this be as simple as a slight compression circuit or just setting the Valve-Master up as if it volume pot was turned much lower(like around unity gain), and have the only control from it be the gain knob?
Would this work? I mean if it did it might just be the greatest Tube/SS hybrid amp you could make for around $70USD

Most of what sounds awesome about (classic) driven tube-tone is over-/hard-driven Power Tubes; more modern tones typically involve preamp distortion (hence, 4+ 12A_7 tubes in modern preamps) instead of (just) power tube distortion.  This isn't to say NO power tube distortion is there; just that the majority of that tone is not from over-driven el34/6l6/kt88s/etc., which is why most modern tones are (slightly) easier to achieve w/o stadium volume or attenuators.

So yes and no; yes, in that you could have a rockin' preamp OD in the situation you describe, and no, you wouldn't have the typical definition of awesome "tube-tone."

try it out, see if you like it; this is all that really matters, no?

[Taylor]

You can definitely do that. I think it's a good idea and I actually think a few people have already done that with the TG. A couple of caveats/notes:

-I am not really a tone fiend, but my guess is that few people would consider the Valvecaster to be representative of good tube amp tone. I think it's pretty cool for a 12v circuit, but nothing like your favorite tube amp clipping.

-Much of what people like about tube amps is power amp distortion, not preamp distortion.

-I don't think you should take it as gospel that "tube amps sound great distorting, SS amps sound bad distorting." IMO this is one of those memes that gets spread without people listening with their own ears. I have rarely been able to crank the TG as it's too loud for most of my play situations, but I have been told by two different guitarist/recording engineer/golden-ears that the TG distorts in a pretty interesting way. It's not necessarily like your favorite tube amp, but it's not hard clipped square waves. My father did a delta blues gig with a TG I built, playing his resonator guitar through it. Most people thought he was getting a great bluesy driven tone, and it was all TG.

Again, I don't want to dissuade you at all because I think a Valvecaster in front of a Tiny Giant is a great idea and would be a fun rig. I would just recommend checking out the amp by itself first, and making up your mind based on your own ears. Nobody on the internet knows better than you do what sounds good to you.

It's true though, that slamming the front end with a booster won't sound good because you'll just be clipping the opamp in front, not the amp itself. So if you do the Valvecaster you might want to bypass the TG's preamp.

[Ark Angel HFB]

You can definitely do that. I think it's a good idea and I actually think a few people have already done that with the TG. A couple of caveats/notes:

-I am not really a tone fiend, but my guess is that few people would consider the Valvecaster to be representative of good tube amp tone. I think it's pretty cool for a 12v circuit, but nothing like your favorite tube amp clipping.

-Much of what people like about tube amps is power amp distortion, not preamp distortion.

-I don't think you should take it as gospel that "tube amps sound great distorting, SS amps sound bad distorting." IMO this is one of those memes that gets spread without people listening with their own ears. I have rarely been able to crank the TG as it's too loud for most of my play situations, but I have been told by two different guitarist/recording engineer/golden-ears that the TG distorts in a pretty interesting way. It's not necessarily like your favorite tube amp, but it's not hard clipped square waves. My father did a delta blues gig with a TG I built, playing his resonator guitar through it. Most people thought he was getting a great bluesy driven tone, and it was all TG.

Again, I don't want to dissuade you at all because I think a Valvecaster in front of a Tiny Giant is a great idea and would be a fun rig. I would just recommend checking out the amp by itself first, and making up your mind based on your own ears. Nobody on the internet knows better than you do what sounds good to you.

It's true though, that slamming the front end with a booster won't sound good because you'll just be clipping the opamp in front, not the amp itself. So if you do the Valvecaster you might want to bypass the TG's preamp.

Well to be honest I've built the valve caster and my first thoughts were how I wish the sound I was getting could just be my amp... the TG seems like an easy solution to my wishes... this brings me to my next "no nothing but would be cool" question.

Would it be possible to build two TG's and wire them some how for push pull operation resulting in a, roughly speaking I know, 40W power amp section?

Could this be done by simpling spliting the signal after the Valvecaster stage, running like stereo into both TGs then joining the TGs possitive and negative leads together before going into what ever speaker(s) you wanted?

Or would this result in some kinda horrible mushroom cloud. XD

Also I was reading along and did we ever find out what was causing the shocks with a PA system? was it just the 48v phantom power or the fact most PA use AC while the TG and guitars use DC. I've got a shock before with 48v Gear when I was playing a poorly grounded amp... would there be a way to ground the TG without messing up what it does?

EDIT: OR... would it be as simple as changing the Amp IC up to something that puts out more?

I only ask because the Amp you listed is obsolete at Mouser and they don't sell it any more... what would be a good substitute?

thanks btw for such a fast response... you are great dude. ^_^

[Taylor]

There are places on the web that sell the amp chip. Of course, it comes in the kit I sell on my site, but if you don't want to buy that, a Google search for the chip should find a few places.

You can't make a bridged amp with 2 Tiny Giants because it is itself a bridged amp. What you can do is split your signal and parallel them into 2 speakers. This is good because doubling your wattage only creates 3db more volume, which is barely perceptible. So you'd be doubling your work effort for almost no gain in loudness. But adding another speaker adds 3db of its own, so a second amp into a second speaker would be more worth it than just doubling wattage.

AFAIK the shocks are nothing specific to the TG. Any time your PA and your amp are on different circuit breakers, there is a chance of a ground potential between them. So this has to do with the wiring in some houses/clubs. It's not an AC/DC thing because all music gear that plugs in receives AC and then turns it into DC.

[Ark Angel HFB]

There are places on the web that sell the amp chip. Of course, it comes in the kit I sell on my site, but if you don't want to buy that, a Google search for the chip should find a few places.

You can't make a bridged amp with 2 Tiny Giants because it is itself a bridged amp. What you can do is split your signal and parallel them into 2 speakers. This is good because doubling your wattage only creates 3db more volume, which is barely perceptible. So you'd be doubling your work effort for almost no gain in loudness. But adding another speaker adds 3db of its own, so a second amp into a second speaker would be more worth it than just doubling wattage.

AFAIK the shocks are nothing specific to the TG. Any time your PA and your amp are on different circuit breakers, there is a chance of a ground potential between them. So this has to do with the wiring in some houses/clubs. It's not an AC/DC thing because all music gear that plugs in receives AC and then turns it into DC.

I will be honest... despite wanting to find stuff as cheap as I can... I can only assume you are making between $6 and $10 bucks per amp kits... and with how helpful you are, and how much you back up you work I'd rather would rather buy your kit than source the parts myself and vero it... I think people who do good work should get paid.