Author Topic: Combo amp Project - Noisy Cricket or Tiny Giant  (Read 275 times)

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Jebull

Combo amp Project - Noisy Cricket or Tiny Giant
« on: January 14, 2018, 12:11:03 AM »
Hello! I've just gotten into building pedals a few months ago - completed 6 builds so far - a SHO/black eye boost, EQD Acapulco Gold, DAM Meathead Dark, ProCo Rat2, zvex fuzz factory, deadastronaut X fuzz! I have been creeping on this site for a while, it along with "guitar FX layouts" has helped me tremendously. I think I'm hooked! I think I'm ready for something new now.

I am making a Combo amp - 1x10 or 1x12. I want to make either a Noisy Cricket or a Tiny Giant build, using veroboard layouts from guitar FX layouts. But I would like to add a few extras if I can manage. I want to know if it's possible and how to go about adding a preamp, specifically the Sunn Model T preamp from the vero layouts site. I don't know if it would work better on either of these or if it would be possible at all. Where would I go on the boards to insert / replace the pre-existing preamp?

I'm also thinking about adding reverb, either a pcb or vero or an un-housed retail pedal. How would I go about this? Where would I insert it on either of these circuits? I also have an Ibanez TB25R that I'm considering cannibalizing - could I use the spring reverb tank from it or would that be too far beyond my capabilities?

I'm thinking I could put it all in a "looper" sized enclosure that I'll mount into the speaker cab.

For the record this is going to be a "mini doom rig" - I live in an apartment and can't play too loud. I'd like for it to work decently with drive pedals, esp fuzz.

Is this at all feasible?
Thanks so much!  ;D

vigilante397

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #1 on: January 14, 2018, 01:16:54 AM »
Welcome to the forum :)

So short answer to your question is yes.

Slightly longer answer:

Both the Tiny Giant and the Noisy Cricket already have preamplifiers, but they could absolutely be removed in favor of the Sunn preamp. For the noisy Cricket remove C6 and everything before it, plug the Sunn Model T pre into pin 2 of the LM386, and voila. Done.



For the Tiny Giant remove the 1uF capacitor and everything before, plug the Sunn pre into pin 3 of the TDA7240 and voila. Also done.



Your other questions get a little more complicated. I am one of the least picky people for reverb placement, as none of my amps have spring reverb or FX loops so I just use a reverb pedal in front of them and it sounds good to me (never had any complaints from anyone else either). So you could easily add an existing reverb pedal before the Sunn preamp. If you wanted the FX loop-ish sound you could probably put the reverb between the preamp and the power stage (depends on what reverb circuit, impedences, stuff like that) and be fine. Personally I wouldn't recommend adding spring reverb. It gets complicated and in my personal opinion smaller reverb tanks just aren't worth the trouble as emulated spring reverb (i.e. Belton digital reverb modules) sound much better.

This should all fit easily into a looper sized enclosure, or if you really like torturing yourself you could probably get everything into a 1590BB. Some people on this forum could probably get it into a 1590A on a dare ::)

Anyway, welcome again, I hope this has been at least somewhat helpful. Keep posting as other questions arise ;D
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

"Tayda's Whipping Boy"

http://www.sushiboxfx.com

Jebull

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #2 on: January 14, 2018, 01:36:51 AM »
Woah! Thank you for the excellent reply! You pretty much answered everything perfectly. Exactly what I need to know. I had actually thought first of the 1590BB haha. I only decided on the looper for aesthetics mainly, with the added bonus of it being a breeze to fit everything. I have a rather large empty 1x12 speaker cab that I'm thinking of using for this.

Yeah I figured the tank idea wasn't worth the trouble! I think ill stick to a belton build or maybe find a cheap biyang yri-reverb. Haven't decided yet. Feel like since this is already DIY,I should go all the way and build the 'verb myself!

So, one more question for now, I'm sure I'll have a lot more one I get started :)
Will the different voltage on the tiny giant matter with the other boards?

Jebull

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #3 on: January 14, 2018, 10:27:19 PM »
As far as I understand, the TG would output 12v. Would the preamp etc. be okay with that?

slashandburn

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #4 on: January 15, 2018, 07:39:36 AM »
Id say most preamp circuits shouldn't be too fussy. I quite often power my pedals and lm386 amps with an unregulated wallwart that outputs about 13v. Some (most? All?)  respond a bit differently.

You could always throw in 9v regulator or go the other way an use a charge pump to get up to 12v where it's needed? I'm no authority on the subject, but those seem like the simplest options if you really need to use different supply voltages. But no I don't think it should matter a great deal in most cases.

vigilante397

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #5 on: Yesterday at 01:08:58 AM »
As far as I understand, the TG would output 12v. Would the preamp etc. be okay with that?

First, on the power supply: If you use the LM338 regulator as shown on the vero layout you end up stepping a 19-ish volt rail down to 12-ish volts, which I think is silly, why not just off a 12V power supply? If you have a 12V supply then you can just use a common rail for everything. Otherwise you have to run your 19V rail into the tiny gian board, then take jumpers from the 12V supply on the tiny giant board. That being said it couldn't hurt to make sure you have proper filtering on your power to keep the noise down. I can elaborate on that if you need.

As for your actual question, the preamp won't care at all. It's all discrete components, and the only difference you might notice is an increase in clean headroom with a higher voltage. Just make sure you use properly rated capacitors (hopefully nobody is using 10V rated caps on a 9V build anyway).

The only concern I would have is if you attach a Belton style reverb build. Belton reverb bricks run at 5V (pretty common operating voltage for digital circuits) and get there by using a 5V regulator. In the world of stompboxes we tend to use something called a linear regulator. They're dirt simple and they get the job done with minimal hassle. But the bigger the difference between the input voltage and the output voltage the less efficient they get. In power supplies less efficient means you're losing a lot of power to heat.

Now this still probably won't be a big deal depending on what you build, but it never hurts to be prepared. The small package (TO-92) 5V regulators would be risky. They are capable of putting out 100mA at 5V, but if you look at the Belton reverb datasheet its max current draw is also 100mA. Now I've never had a Belton project draw that much, and they list typical operating current at 60mA, but knocking a 12V supply down to 5V will give off quite a bit of heat even at 60mA, so you would risk the regulator shutting down. I would recommend paying an extra few cents and getting one of the TO-220 package 7805 regulators with the heatsink tab on the back. Much more robust and less likely to overheat on a small load like that. (slightly off-topic: I had a ver power-hungry pedal that used a linear regulator and pulled 600mA, and when I used a 9V power supply it ran fine but with a 12V power supply it overheated in about 2 or 3 minutes.)

Sorry if this answer was overkill to your question, I get excited sometimes and start to ramble ::)
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

"Tayda's Whipping Boy"

http://www.sushiboxfx.com

Jebull

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #6 on: Yesterday at 04:21:37 PM »
Oh. Hmm. For some reason I hadn't even considered using a 12v supply to begin with. So I could leave off the regulator section entirely. Cool. I guess because of the whole focus on using a "laptop power supply" I didn't think about that. lol Thanks for that tip! I would still need a 4A one correct? That would still easily cover the Reverb, right? That sounds like it would be fairly easy to find too.

Thanks so much for your help guys! Since posting this I've been slowly making my way through the original Tiny Giant thread on here... which is 53 pages.... but I've learned a great deal since posting this! (also I'm sorry for making an entirely new thread for something that's already been beaten to death, but that just seemed like it may already be exhausted)

So without the preamp and voltage reg sections, this vero will be TINY. Nice! Maaaybe just maybe I can figure this out enough to draw up my own layout for it. :) I have a layout making program.. but I'm still sadly almost a total novice when it comes down to it. I'm not the best in the world with schematics yet. I'm basically still just "painting by numbers" from vero layouts. I'm very much working on changing all of that now though! This project has helped tremendously with that!

OKAY. So let me see if I understand this correctly. I would want to go:  Reverb > preamp > TG
I could power these all from the 12v. Could I simply run power to the TG, then run power to the other 2 from the TG with a regulator between the reverb and TG? Also, the regular needs caps before and after? or something like that? I'm not entirely sure how to do this. Nor do I have a clue how to word that to google it or I would. I never want to come across as needy or wanting to be spoon fed :P Oh and also, the power filtering. Yes please elaborate! haha

Thank you so much again!

P.S. This would be all I would need of the TG schematic, right?


PRR

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #7 on: Yesterday at 10:55:46 PM »
> stepping a 19-ish volt rail down to 12-ish volts, which I think is silly, why not just off a 12V power supply?

At the time it was proposed, 12V supplies cost money, eBay was flooded with Dell flaptop supplies at $4 and less.

The rise of LED lighting has increased the supply (and lowered the price) of 12V supplies. Meanwhile the Dell flood has abated toward $8. So *now* your point may be on-point. There's still the advantage that a Dell-branded lump is a known-good product, while some of the cheap 12V supplies are dubious.

vigilante397

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #8 on: Today at 12:43:31 AM »
There's still the advantage that a Dell-branded lump is a known-good product, while some of the cheap 12V supplies are dubious.

Which is why I wanted to talk about filtering. The 19V Dell supply explanation makes sense though, I guess I didn't really get into stompboxes (and amp building) until the 12V lighting supplies were around as I've always had something similar floating around. Definitely answers a question I always had and never asked anyone :P

But anyway, to your questions:

I would still need a 4A one correct? That would still easily cover the Reverb, right?

Yes and yes.

As for the layout, I would recommend trying a layout of your own and I would be more than happy to take a look at it and double-check it. I had been building for quite a while before I felt comfortable making layouts, and to be completely honest I think PCB layouts are a million times easier than vero layouts :P

As for the order, you could go Reverb > Preamp > Tiny Giant or you could try Preamp > Reverb > Tiny Giant. Depending on how you build them it wouldn't be very difficult to try swapping the order, especially if they're on separate boards.

You could run all of your boards off of the same 12V supply, just running a line to each from the power supply. Any reverb circuit that uses a Belton brick will already have a 5V regulator as part of the design, so you just need to worry about getting 12V to there and the regulator will take care of it. But as I said before, I would recommend one of these instead of one of these as the regulator for the reverb.

Power Supply Filtering
Regulators tend to have capacitors for high-frequency filtering on both the input and the output. Obviously our pedals are powered with DC, but the cheaper the power supply the more likely there is to be some AC leakage (ripple) on the line, which goes back to what Paul was saying about the laptop supplies. You'll notice that if you power a pedal with a cheap power supply you may hear some high-pitched squealing or general "noise," whereas if you use a One-Spot or any of the other specifically designed power supplies they are beautifully quiet. This comes down to filtering.

LEDs are very tolerant of noise on DC power supplies, which is why you can buy 12V supplies super cheap; there really isn't much to them. Audio circuits obviously need to be significantly quieter. This is why most pedal schematics have a 100 ohm resistor in series with the power input then a 100uF and a 100nF (or something similar) between the positive and ground rails. Resistors block AC signals, which means one in series will drop ripple levels, and capacitors allow the flow of AC signals, so the ripple will go through the capacitors to ground, leaving you with a much cleaner line (this is a simplification to a degree, but applies well enough to stompboxes).

Computers and other digital circuits usually require VERY clean power to operate, which is why, as Paul mentioned above, laptop power supplies already have MUCH more filtering than a 12V wall-wart supply will, and therefore don't need as much filtering in the circuit. They are also more stiffly regulated, meaning that you are more likely to get the voltage they are supposed to give you regardless of the load, whereas many 12V supplies with no load will read 14V. Any DC supply you can get for $3 on eBay can work, but you may need varying degrees of filtering (generally with capacitors) to get the same results as you would with a pre-filtered supply.

P.S. This would be all I would need of the TG schematic, right?


Yes. You'll notice you have a couple fat capacitors on pin 6 between the power supply and the chip? Filtering 8)

Never be afraid to ask questions. Everybody needs help and this is a great place to get it. When I first started Paul (PRR) here gave me quite a bit of help on a wide variety of problems I had. There are many extremely knowledgeable people on here (much moreso than me) and everyone is super cool about sharing knowledge. That's kind of what the whole forum is about. Knowledge and sweet, sweet tone. 8)
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

"Tayda's Whipping Boy"

http://www.sushiboxfx.com

bool

Re: Combo amp Project - Noisy Cricket or Tiny Giant
« Reply #9 on: Today at 06:18:06 AM »
If you're a bit more adventurous, the vintage but still available TBA800/810/820 chipamps have inputs of sufficiently high impedance so you can plug a guitar directly into the chip without any buffering. You can realize the tone control inside the chipamps' nfb loop. (ie, it's a one-chip affair all in all).