Building the Tiny Giant amp

[space_ryerson]

Thanks PRR! I'll give it a shot.

edit: I gave it a try without the second 10k pot. Although the synth has a volume control, the amount of noise that gets amplified makes me think I'll need to add the second pot. Even with the synth off, just having the second cable plugged in adds a degree of noise. It's too late to drill tonight, so this will have to wait until tomorrow.

[Psychemic]

I just built my Tiny Giant Amp. I'm going to use it with my DIY two channel amp with "Dr. Boogey" & "English Channel" as a preamps. In the build pdf it says that "you can take the regualted voltagefrom here...", so does it mean I can use that to give power to each preamps? Do they all have to be in the same ground? Thanks!

[G. Hoffman]

I built one of these as a test amp for my electronics workbench.  I liked it enough, I ordered three more PCB's, and am going to make test amps for some of our repair guys at the shop, so they can stop having to go over to our shop amp, which is frequently busy with someone else's job.

I'm also thinking of making a couple for use as the stereo "wet" amps in my dry/wet guitar rig (one or two "tone" amps that are always dry, and then taps from their output transformers get sent to all the time based effects - chorus, delay, etc. - which get returned to the "wet" amps.


Gabriel

[StarGeezers]

   I've been running the TG as a "second" amp ...  My guitar has a piezo bridge (Mike Christian) and i'm running that > the TG , the magnetics into a homemade tube amp ... Really get some interesting Tones  by using both at the same time ... very FULL ...  For the rhythm bits I just turn down the tube amp (guitar V pot)   ..    And if you spread the speakers apart , it really increases the Hugeness of the sound...  

[modsquad]

Forgot to post this here when I finished it, I might add some sort of tone control to it but its nice and loud so far

Did a side by side with a .22 caliber and they both had about the same amount of clean headroom with the cab I was using.

Wouldn't that make this the "Little Green Sprout"...

[Taylor]

I just built my Tiny Giant Amp. I'm going to use it with my DIY two channel amp with "Dr. Boogey" & "English Channel" as a preamps. In the build pdf it says that "you can take the regualted voltagefrom here...", so does it mean I can use that to give power to each preamps? Do they all have to be in the same ground? Thanks!

In general, all the grounds in any effects/amp system will connect. You can connect your grounds from your preamps to the TG board, or to the guitar input jack ground, which would probably be easier.

Yes, that point can be used to send power to your preamps. Note that the voltage is more than 9v - it will be 11.6v if you use standard values on the TG PCB.

[Psychemic]

In general, all the grounds in any effects/amp system will connect. You can connect your grounds from your preamps to the TG board, or to the guitar input jack ground, which would probably be easier.

Yes, that point can be used to send power to your preamps. Note that the voltage is more than 9v - it will be 11.6v if you use standard values on the TG PCB.

Hey thanks for the reply. What I read at least Dr. Boogey can handle 18 volts so 11.6v shouldn't be a problem.

[jkokura]

Hey Taylor, I sent you an email but haven't heard from you yet.

If I wanted to go with a bit more traditional power supply, using a transformer and such, is there a resource you recommend, or even an idea of what kind of transformer I should be looking for? I have very little experience with that kind of power...

Jacob

[Taylor]

Hey Jacob, sorry I hadn't answered your email yet.

I actually don't know much about power transformers - part of the reason I wanted to design this is to have an amp that didn't need a PT, for size, cost, and safety reasons. You might actually want to go with a different amp PCB if you're going to use a PT - you're going to need to add the diode bridge and big caps for the power supply, so you might as well go for a PCB with all that integrated on the board, rather than having to add a second board for the power supply.

D'oh, just checked and I see you've ordered the TG kit and received it already. 

If the only reason you want to do that is to have an IEC inlet on your amp, my personal solution was this:

Use a hole saw to cut a ~1" hole in your box, mount the laptop supply inside the box/cab with its AC inlet inside the 1" hole. You now can plug in the laptop supply's AC cable, and remove it for easy transport, etc.

You can still do a linear power supply with the TG, but I can't give too much guidance on that I'm afraid. You might want to bypass the voltage regulator, but I'd check out some solid state power amp schematics to see what's normally done.

[jkokura]

I didn't even think about that Taylor! Brilliant.

Got any eBay links for a good powersupply?

jacob

[PRR]

> Although the synth has a volume control, the amount of noise

Raise the mix-resistor on the line/synth side to 33K, 100K, or more.

Ideal goal is for synth hiss-floor to come out the speaker similar to room noise-floor (different in the midnight lab or the happy-hour saloon, some judgement required), and for synth maximum output to come out at or slightly above the Giant's full ~~20 Watt limit.

It may not be possible to meet both goals in a quiet space. But in a paying-gig situation, when the max-output gain is right, the hiss is often a non-issue (below crowd noise).

This also improves gain in the preamped path, by shifting the mix from 50:50 to something like 80% preamp 20% line.

[PRR]

> If I wanted to go with a bit more traditional power supply, using a transformer

Living in the past.

Assuming full 20W output, the raw DC should be around 11, 12, 14V with at least 2 Amperes. OTOH at idle current goes near-zero yet voltage must not rise much over (IIRC) 18V.

That's a very tight spec for a small transformer. Only 28% different, and small PTs have 20%-25% regulation, plus 5% or more uncertainty in wall-voltage, plus you can't get the eXacT voltage rating you want without custom-costs.

18V-14V 2A DC means a "10V or 12V 3A" transformer, a 10A FWB, and about 10,000uFd of 20V cap. And a line-fuse! Depending where you shop, that's $20-$40 of heavy metal.

Plus the extra-care needed to wire wall-voltage without shock or fire. You can do it; it is much better if some other person checks your work (we are most blind to our own oversights).

OTOH apparently excess flatop supplies sell REALLY cheap. The wall-voltage safety issues have been DEALT-with, in design, testing, certification, and by the fact that they made thousands of them before yours (not a "one-off"). And the supply is regulated just a little above the voltage we need, so that a not-excessive $2 regulator can nail the supply voltage for-sure.

And yeah, if you don't like cord-bricks, tuck it inside. These bricks do need cooling, but for the typical flaptop brick and this amp they don't really need to be out in the open.

[StarGeezers]

   Having built many Tube guitar amps , with big power transformers and the like , when I saw the TG , and the power supply choices  , I was totally impressed with the Beautiful Simplicity of this amp ...       I must confess , just building this  for the Fun of it ,but turns out I was totally surprised how well it worked and how really GOOD it sounded ...
 
 Great having the PS and it's heat and noise far away from the amp...  aside from the PS "affordability" ...(read: Cheap)   I think Taylor did a Super job figuring all this out . and after having played on it , I wouldn't change a thing ...  

Ps.  I did try it out at band rehearsal , and through my 2-10" Celestion Rolas (total 4 R)  , it Was LOUD enough to keep up with the band ...   Very Impressive !!!  ...  

  Looking forward to building another one soon ...  

[phector2004]

I didn't even think about that Taylor! Brilliant.

Got any eBay links for a good powersupply?

jacob

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=290429762390#ht_2793wt_1139

Here's the one I ordered. Voltage wasn't too high, puts out 4A, and it's only $12 shipped to Canada

I'll follow-up when I receive it, hopefully it comes with a power cord!


As for mounting it into the enclosure, could it make the amp really noisy? Might not be a problem for me, as I'm using a D or C-sized enclosure, but in a BB it would be cramped in next to the board  


EDIT #2:

Anyone know where I can get a 6.0mm x 4.4mm DC jack? The local place doesn't have it and none of the DIY stores carry it either... Would be nice to be able to use one PSU for many amps instead of lugging plastic boxes and cords, and having to figure out which one goes to which amp... 

[pruttelherrie]

So, finally some pics of my build. I find 'Tiny Giant' not as awe-instilling as for example 'Tiny Terror' (already taken, I know) so I went with 'Tiny Trepidation' to still have a sense of unease.







And although I renamed it, attribution where needed: (too bad it's going to be covered by velcro for pedalboardmounting!)



The waterslide decals got attacked by the paint...

And finally a gutshot:



The PCB is mounted 'upside down' so I could place the pot, switch and led where they are. Hell to mount it though, I had to glue the plastic washer and the nut to the chips before sliding the unit in place and screwing the chips to the side. The remaining space is going to be filled by either a preamp/compressor/whatever or by a 16V -> 9V power supply regulator to be connected to the second PSU plug so I can power the rest of the pedals from it.

[Taylor]

Your photos aren't showing up for me...

[pruttelherrie]

Hmpf, dropbox weirdness. Fixed the links in the post, should be ok now.

[p_wats]

Nice builds, guys!

I'm curious now, what would stop someone (say, me) from adding a 9v out jack to their build to power pedals, taking it from the pad on the board previously mentioned (supplying 11v or whatever it actually was)? Ground issues, I suppose?

[StarGeezers]

   Just one more little question .... mine has a little Hum , except when I touch the guitar strings ....  I was wondering if it would be effective to run a ground wire jumper from the input jack ground lug , to the negative side of the DC jack ...

[pruttelherrie]

I'm curious now, what would stop someone (say, me) from adding a 9v out jack to their build to power pedals, taking it from the pad on the board previously mentioned (supplying 11v or whatever it actually was)? Ground issues, I suppose?

That was exactly my plan with the remaining space in my build.

mine has a little Hum , except when I touch the guitar strings ....  I was wondering if it would be effective to run a ground wire jumper from the input jack ground lug , to the negative side of the DC jack ...

It already is connected, if you used both pads (GND and Input) on the PCB for connecting the inputjack to.