Building the Tiny Giant amp

[myramyd]

Hey Taylor,

I'm happy to report that I have the TG working now after installing a new chip and reflowing some joints.

I'm unhappy to report that I'm an idiot...

I didn't realize that I had the polarity reversed on the power jack. I wired the power supply plug to be center positive and didn't make the connection that it's the opposite of how pedal PS are wired.

Luckily I didn't blow the replacement chip--it just got fairly hot while I tested voltage and made the realization.

At least it's working now! Lesson learned...

J

[PRR]

> polarity reversed on the power jack. ...it's the opposite of how pedal PS are wired.

Something for the manual.

[Taylor]

> polarity reversed on the power jack. ...it's the opposite of how pedal PS are wired.

Something for the manual.

Huh? The Tiny Giant can be wired however you want, but in general most people are wiring them the same as pedals - center negative. So there's nothing special about this circuit that requires you to wire things differently from the way you're used to.

[haroldjenkins]

Hi again,
I've decided to trash the preamp I had built for this, since I did a questionable job on it and it had some issues. The TG works great however.
I'm about to build another preamp using subminiature pentode tubes.

Would the input impedance of the TG play well with the high output impedance a tube preamp, or should I use a buffer on the output? I'm thinking it will be OK, since the first preamp I tried was a JFET design, without a buffer- and it was PLENTY loud. Just want to be sure.

[neutronarmy]

I know this is a strange question, but is there anything that can be easily substituted for the isolation material? I managed to lose one of the two pieces and was hoping to replace it with something I can find locally, rather than making an online order for such a small part. Thanks for any help folks!

[Taylor]

I know this is a strange question, but is there anything that can be easily substituted for the isolation material? I managed to lose one of the two pieces and was hoping to replace it with something I can find locally, rather than making an online order for such a small part. Thanks for any help folks!

Yeah, anything that is an electric insulator will work. Rubber, silicone, plastic, wood, paper, cardboard, but you need to be really serious about checking that there's no continuity with the enclosure this way, and of course fashioning something that's the right shape/size is tricky. I can also mail you some replacements for the price of shipping.

Hi again,
I've decided to trash the preamp I had built for this, since I did a questionable job on it and it had some issues. The TG works great however.
I'm about to build another preamp using subminiature pentode tubes.

Would the input impedance of the TG play well with the high output impedance a tube preamp, or should I use a buffer on the output? I'm thinking it will be OK, since the first preamp I tried was a JFET design, without a buffer- and it was PLENTY loud. Just want to be sure.

The built-in preamp of the TG is basically just an opamp buffer, so I'd go from your tube preamp output to the regular input of the TG and it should work well.

[haroldjenkins]

The built-in preamp of the TG is basically just an opamp buffer, so I'd go from your tube preamp output to the regular input of the TG and it should work well.

I suppose I should have paid more attention to the schematic. There is TL072 with JFET inputs there cleverly disguised as an opamp. Thanks for the reply, Taylor.

[arma61]

Hi Taylor and you all

this is just to report I just became part of the Tiny Giant Amp family!!! worked at first go! Deadly silent and great sound even into a home stereo 2 ways speakercabinet, cannot imagine it into a proper guitar speaker!!!

just one question about the PSU, my one has 3 wires, 2 braids insulated from eachother. I get 19.5V and I use to power up the TG, then in the second bread there's another blu wire and I can get 12.5V with the 1st bread. Do you thinks I may use this "spare" wire to power up my pedalboard after a 9V regulator ckt, ot it will suck current from the TG?


thx m8!!

ciao
Armando

[waltk]

just one question about the PSU, my one has 3 wires, 2 braids insulated from eachother. I get 19.5V and I use to power up the TG, then in the second bread there's another blu wire and I can get 12.5V with the 1st bread. Do you thinks I may use this "spare" wire to power up my pedalboard after a 9V regulator ckt, ot it will suck current from the TG?

Well done on the TG build - it's always nice to have a build work on the first try.

To answer your question, it depends on how much current is available from the PS, and how much is required for the pedalboard.  It's also possible that the 19.5V and 12.5V output are rated for different current output.  In general, supplying a pedal would require a tiny fraction of the output available from the PS.  Many pedals only draw a few ma, digital pedals might 90 or 100 ma.  Unless you have a huge current requirement on the pedalboard, it should be fine.

[arma61]

Thx Walt

I've just looked again at the sticker on the back of the PSU, there's no mention of this double voltages, it just says, among other things , output 18.5V at 3.5A.

So I'd better leave my pedalboard powered up with its own PSU, to avoid problem and the search for 3 prongs jack and plug

Thanks again
Ciao

[phector2004]

I've had a very difficult summer, but I finally got this one built!  

It's great! Works well in the same box as a Dr. Boogie, just biased and it was ready to play. I want to do a volume test but I doubt the neighbors would be too happy at this hour!

Thanks for designing this and making kits available

[Hupla]

Hey guys, I want to include a 9v power out to power my pedals with this amp and I was wondering if you can run a 9 volt regulator off of the 12 volt regulator in this build?

[waltk]

This has been a frequent subject of posts in this thread.  Take a look back at some of the other posts.

Short answer: Sure (with a couple minor caveats).

[arma61]

Hi there


Almost finished!!

Put the PSU directly into the enclosure, then I had a "Condor Cab Simulator" board laying around so I put it inside to test, OMG!! perfect!!! it's powered up directly with the PSU, a DPDT with a Millenium bypass et voillà, selectable CabSim depending on the external cabined available!!

Then I just take the power from the PSU connected to a small perfboard with a LM7809 and a couple of caps, and got 9V on the back to power up my pedalboard! perfect too, no hum no noise....... (btw yesterday I left it on (unattended!!!    ) for 3 hours, nothing hot, if I touch the bottom plate, where all the heatsinks are connected my hand is warmer than the plate.)


.................Taylor what have you done!!!


Still need something to be fixed, ie cut the PSU cables and put 4 fixed resistors instead of the pots on the cabsim, and redo the wiring even though I may leave as it is now.... it sound perfect!!!



Rear

Details!


Guts!



Ciao!

[waltk]

Almost finished!!

That's beautiful. Nice work!

[Taylor]

Yes, looking good Armando. 

Thanks again to Walt for his many contributions to this project.

[Hupla]

This has been a frequent subject of posts in this thread.  Take a look back at some of the other posts.

Short answer: Sure (with a couple minor caveats).

OK so I looked back and I can't find anything other than people talking about doing it. From my understanding as long as the on board regulator in the tiny giant amp has an output of higher than 11.5v (as according to the datasheet of my 9v regulator) I can attach this output straight to the input of my 9v regulator?

Now I can suspect it's not as easy as that. So does anyone know of any problems that might come about from this?

[waltk]

Now I can suspect it's not as easy as that. So does anyone know of any problems that might come about from this?

No problems.  It's really as easy as that.  As long as the power supply can supply all the current required, and the add-on 9V regulator can supply the current for the pedal(s) you want to power, it should be fine.

[Hupla]

Now I can suspect it's not as easy as that. So does anyone know of any problems that might come about from this?

No problems.  It's really as easy as that.  As long as the power supply can supply all the current required, and the add-on 9V regulator can supply the current for the pedal(s) you want to power, it should be fine.

Thanks. How could I test the power supply for this? Is there a ball park figure I should be leaning towards for a power supply? Also my 9v regulator max's at 1 amp so I think that should be enough as I wouldn't have many on at once. At most I would be using one digital pedal?

[waltk]

How could I test the power supply for this? Is there a ball park figure I should be leaning towards for a power supply? Also my 9v regulator max's at 1 amp so I think that should be enough as I wouldn't have many on at once. At most I would be using one digital pedal?

If your 9V regulator can handle 1 amp (e.g. like an LM7809), and is in a TO220 package, then it probably wouldn't even break a sweat - even with a fairly loaded pedal board.  With one digital pedal, and a handfull of analog pedals, you probably don't need more than 200ma for all the pedals together.  I doubt that you would even need a heatsink for the add-on regulator.

Taylor was pretty conservative in specifying the power supply for the TG.  If your laptop power supply handles 3.5+ amps (as marked on the label), there should be plenty for all.  Seems like the TG draws about 1 amp when it starts up, then settles down to a couple hundred ma at moderate volume levels.