Building the Tiny Giant amp

Taylor · February 14, 2011, 11:26:46 PM

Hmm, if I understand you correctly, the "grommets" are just the regular holes that the parts go in like any other PCB. If you're used to single-sided boards etched at home, the difference between that and these is that these are "plated through holes". The pad that you would solder to on a single-sided, home-etched board is still there, but the inside of the hole has metal plated into it to make a better connection, and so that you can solder from either side of the board, and to connect the top and bottom copper layers.

But you can solder to it just like any other kind of pcb. No special tool is required. You don't need to get the iron inside the hole, just heat the pad and component lead as you normally would with any PCB.

You'll be fine with an 18v supply. I'm using a 19.5v one and a box smaller than a standard RACO.

Your ground connection for pedals should probably be the ground tab on your power inlet jack.

David · February 14, 2011, 11:56:34 PM

Quote from: Taylor on February 14, 2011, 11:26:46 PM
Hmm, if I understand you correctly, the "grommets" are just the regular holes that the parts go in like any other PCB. If you're used to single-sided boards etched at home, the difference between that and these is that these are "plated through holes". The pad that you would solder to on a single-sided, home-etched board is still there, but the inside of the hole has metal plated into it to make a better connection, and so that you can solder from either side of the board, and to connect the top and bottom copper layers.

But you can solder to it just like any other kind of pcb. No special tool is required. You don't need to get the iron inside the hole, just heat the pad and component lead as you normally would with any PCB.

You'll be fine with an 18v supply. I'm using a 19.5v one and a box smaller than a standard RACO.

Your ground connection for pedals should probably be the ground tab on your power inlet jack.

Excellent to all the above. Exactly the answers I was hoping for.

StarGeezers · February 15, 2011, 12:49:48 PM

Taylor , got my Kit !! What a Beauty , and TINY ...

Very COOL !!!

This just looked like too much FUN to pass up !!! Thanks , Dude !!!

Brymus Possibly

... Doing Good , got a CD ... Surprisingly very Close to Taylor ... Yes , still Croaking ...

culturejam · February 15, 2011, 04:13:03 PM

Got mine today as well. Can't wait to get it going.

thedefog · February 16, 2011, 09:46:28 AM

I'm noticing on mine that there is some very low level distortion going on, even with the guitar volume rolled down and volume on the amp low. Where could something like that come from if it isn't dependent on the input volume?

Taylor · February 16, 2011, 01:54:35 PM

The distortion really is the same regardless of input volume, or it's there at any input volume (but more distorted at louder in volume)?

David · February 17, 2011, 11:26:34 AM

Taylor, I still have to connect the "offboard" components on mine.

What I need to know is, how much current can the "offboard connection" really supply? Can it go to an amp?
If not, I can always use a 9V wall wart like I do now. I had thought about feeding the "offboard connection"
through a LM317 set up to deliver 9V.

It would sure be nice to just have one power cable coming to my pedalboard.

Taylor · February 17, 2011, 02:29:03 PM

The onboard voltage regulator has a max current capability of around 5 amps as I recall, but check the datasheet. Assuming your power supply puts out that or more, the current available for pedals would be that minus the actual current draw of the amp. I haven't had a chance to measure current draw yet, but I wouldn't be surprised if it was something like 3a or less in regular use.

David · February 17, 2011, 02:54:54 PM

Quote from: Taylor on February 17, 2011, 02:29:03 PM
The onboard voltage regulator has a max current capability of around 5 amps as I recall, but check the datasheet. Assuming your power supply puts out that or more, the current available for pedals would be that minus the actual current draw of the amp. I haven't had a chance to measure current draw yet, but I wouldn't be surprised if it was something like 3a or less in regular use.

So that pin that is marked for offboard connections in the build document does not connect to the half of the TL072 that is creating the bias voltage, then. OK, got it. EXCELLENT!!!!!!!!!!!!! THANK YOU!!!!!!!!!!

Kain · February 18, 2011, 07:24:33 AM

Just ordered Tiny Giant amp + Christine, can't wait. Thank you.

thedefog · February 18, 2011, 10:56:28 AM

Quote from: Taylor on February 16, 2011, 01:54:35 PM
The distortion really is the same regardless of input volume, or it's there at any input volume (but more distorted at louder in volume)?

It's there regardless of input volume. Not more or less at different levels (unless it's cranked and it's breaking up obviously).

Taylor · February 18, 2011, 02:46:23 PM

Hmm, that's quite strange. Generally, distortion means clipping. But I can't think of any normal way that something could clip where the amount of distortion does not vary with input volume.

Are you plugging your instrument straight into the TG? Is it a guitar or something else? If a guitar, is it a normal passive one?

defaced · February 19, 2011, 02:59:07 PM

Got mine built. A couple of naked box shots and the power adapter I'm using, $9.80 on eBay. I really dig this project. And it plays just fine with a 16 ohm cab.

Fiber isolation washer to keep the output jack, well, isolated from the chassis which is at ground potential.

$9.80 on ebay. VAIO Laptop 19.5V 4.7A from seller laptopz-outlet.

http://cgi.ebay.com/AC-Power-Adapter-Charger-fr-Sony-VAIO-Laptop-19-5V-4-7A-/310229426156

waltk · February 19, 2011, 03:13:24 PM

QuoteGot mine built.

It's beautiful. Nice work!

doug deeper · February 19, 2011, 09:26:35 PM

Ordered mine!
Gonna try it for monitoring with my mono reel to reel recording rig.

David · February 20, 2011, 10:17:45 PM

I'm working on testing mine now, which is proving interesting since my guitars are in the shop and I'm
trying to improvise using a signal generator. I had issues with the op-amp not being in all the way and
a faulty mute switch. I tracked these down and I'm going to put a different switch in.

What I'm noticing is that the 10K is not acting quite as I expected. It was marked 10K audio, so I don't
THINK it's linear, but it's not acting like it's logarithmic. I get nothing for probably a third of the pot's travel,
then the volume climbs like a Saturn V taking off.

Any ideas?

Hides-His-Eyes · February 21, 2011, 06:03:43 AM

I think I'm going to build this in a box with one of those FET Fender blackface Preamps all in one box.

Not really a related question but say I wanted to use a MAX1044 to run that at 36V; the max the 1044 can take is 9V, right? Would I want to use a regulator for that, or just run a voltage divider into an op-amp buffer at the full voltage?

defaced · February 21, 2011, 09:10:08 AM

I don't think you can. http://pdfserv.maxim-ic.com/en/ds/ICL7660-MAX1044.pdf

From the data sheet:

QuoteAbsolute Maximum Ratings
Supply Voltage (V+ to GND, or GND to VOUT)....................10.5V

It looks like you're limited to 10.5v, or we'll call it 10v input, and if I'm reading that right, 10v max output. It looks like they stack the Vout on top of Vin to get voltage doubling. I'd verify this information, I've not read the entire data sheet or really worked with this device.

Hides-His-Eyes · February 21, 2011, 09:44:30 AM

There's a way to get 36V using diodes; it's on geofex.

Skruffyhound · February 21, 2011, 03:27:04 PM

You can get there with a charge pump, but I don't know what's happening on the current side of things.

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Building the Tiny Giant amp