Combo amp Project - Noisy Cricket or Tiny Giant

[Jebull]

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! 

[vigilante397]

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

[Jebull]

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]

As far as I understand, the TG would output 12v. Would the preamp etc. be okay with that?

[slashandburn]

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]

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

[Jebull]

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 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]

> 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]

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

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

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

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.

[bool]

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).

[Jebull]

Excellent guys! Thank you again for all your help!

Yeah that totally makes sense about the 12v power supplies! I think I see a few nice candidates on Amazon. Nice.

Okay, so I should add a cap or two before the power supply on the Reverb and the Preamp to filter out potential noise. Right? OR I'm assuming find a better PS that is designed for audio equipment. Either way, makes sense! (I'm guessing I should go ahead and add the filters to be safe regardless of the PS used.)

So, I decided to go ahead and take a stab at making a layout since that schem seems so dead simple. Even I could wrap my head around it! (hah, I hope..) Warning: my first attempt at this! It SEEMS that this is right to me, but of course it could be horribly, horribly wrong.  How'd I do? Any ways I could improve it?

I tried my best to keep the chip to the side so I could easily use the case as a heatsink or mount a standalone one. The one thing I wasn't so sure about was the "2" terminal of the chip. As far as I understand this is for a "standby" function, which I have no desire to implement. I only want a power switch! So I added a "double link" for the jumper so I could take it to ground, is that necessary? Or could I just leave it open?

BTW I totally agree on PCB being easier, but I don't really want to take that dive yet. I'm totally fine with vero and I'm familiar with it. Plus this is itty bitty!

Now for another question. I've been thinking about the reverb, and I would like to possibly set up a footswitch option for it. I've been reading some about relays and jfet switches and such. How hard would it be to implement this in a 1/4" jack format, with a relay, so I don't have a long audio loaded cable? If I did do it I would still want a bypass (on/off?) switch for just the reverb along side the footswitch, so I could use either. If this is needlessly complicated, I have no problem only using a switch on the amp, I can walk just fine.. I just like options

Oh and I do fully intend to try out the order of the reverb and preamp to decide which I like better!

Thanks bool, at some point I'll definitely check into that TBA800etc idea, I'm intrigued!

Thanks again! This forum is absolutely fantastic! I honestly did NOT expect to get this much help, as most sites are very adamant on the whole "figure it out yourself" bit.. Which I 100% understand, but hey we all have to start somewhere right?

sorry about the long winded post lol..

[vigilante397]

Your vero layout looks good to me, but if you don't want the standby function you need to ground pin 2, so definitely make that a double link. As for improvements, the only thing i would really suggest is leaving extra space on the corners for mounting holes to mount to the chassis. Mounting is generally kind of optional in pedals, but I absolutely recommend it in amps.

Do you have an idea what reverb you're planning on using? Most will already have some filtering designed in, but obviously it never hurts to add more as long as you've got room for it.

As for relay switching, it really comes down to how much time and money (but mostly time) you want to put into the amp. R.G. Keen wrote an excellent article talking about different methods and considerations for relay switching, I would highly recommend giving it a read: http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm

If you decide that's something you really want to do we can definitely figure it out, but I would recommend having a read through that article and deciding how bad you want it

Thanks again! This forum is absolutely fantastic! I honestly did NOT expect to get this much help, as most sites are very adamant on the whole "figure it out yourself" bit.. Which I 100% understand, but hey we all have to start somewhere right?

This forum is my #1 favorite place on the internet. Figuring things out for yourself is great, but giving you a background and a push in the right direction so you can get started is cool too Because seriously, what's the point of a forum if nobody's going to help?

[Jebull]

Excellent! I'm proud of myself. haha 
Oh yeah! I was already intending to leave room for mounting holes, guess I just forgot. Not a big deal to add though. Especially since I'm probably gonna put it in a huge looper box. Thanks!

I'be been eyeing these mostly so far, I haven't done a ton of looking yet though, and I also haven't ruled out PCB builds either:
http://tagboardeffects.blogspot.com/2012/04/box-of-hall-reverb-culturejam.html
http://tagboardeffects.blogspot.com/2016/04/madbean-ping.html
http://tagboardeffects.blogspot.com/2014/07/rub-dub-reverb.html

I'm gonna do some more looking soon! I really don't know an incredible amount about reverb setups. I just know that when I got my current amp without built in Reverb, I've been missing it.. and been too lazy so far to buy/make a pedal.

I'll definitely take a look at that relay article! Sweet. Definitely not a huge deal to have it or not, but I feel like it'd be nice.

Yeah, this site is fantastic! I'm so glad I decided to do this project, it has exponentially improved my knowledge and skills as far circuits and pedals and such go!! Thanks again! You've been an incredible help already Vigilante!

Hopefully next month or so I can start actually building this! I've got a busy few weeks coming up. Now I guess soon I'll need to decide if I wanna go through the trouble of tolex or just find some good paint.. Hmm. 

[vigilante397]

I've built the box of hall (my first reverb build, using that exact layout actually ) and I liked it, I've heard good things about the ping (and I trust anything Madbean makes, super cool guy), and the rub-dub is kind of a simplified "bare-bones" Belton reverb. But if you look at the layouts you'll see that all of them have filtering capacitors on the inputs and outputs of the 5V regulators.

So my recommendation is to build everything as-is and trust the filtering already built in, then if you find it to be noisy when you try it with the power supply you can add a separate small board just for power supply filtering and use that as the main distribution to all of your boards.

Let me know when you start building, progress pictures are always cool

As for tolex vs. paint, for an amp that's just for home use and won't be dragged around to gigs and whatnot paint would be fine, but for anything that needs to be more rugged I would lean towards tolex.

[Jebull]

Okay, cool! I'll definitely do that. I'm leaning toward the BOH, but knowing me I'll change my mind 6 times before I get to it. lol!

Yeah I figured the only reason I would NEED to do tolex is for ruggedness and travelling, but with this project I'm really more concerned with trying new things and going all out, just for the sake of it. Plus I wanna make it purdy That being said, tolex looks like a huge PITA, so I'm sure I'll be going with paint.

Definitely going to be posting progress pics once I get started! I'm excited!

[vigilante397]

Yeah I've never worked with tolex before as I just had somebody else build the cabinet for all of my amp builds But I'm planning to try it out on the next build (hopefully in the next couple weeks) mostly just to see if I can do it.

[Jebull]

Yeah, I'm sure I'll eventually give it a shot with some project, just maybe not this one haha.

So, a few new questions:

1. How on earth do you wire an "on-on-on" switch with a bi-color or rgb (?) LED. In other words, I want the channel selector switch for the Sunn preamp to have 3 different status LEDs. One for Normal channel, one for Bright channel, and one for both. I'm assuming I'll need a 3pdt or a 4pdt? I've been google for a while now and I can't seem to word it right. haha. Plus switches still somewhat overwhelm me in general.  This may not even be worth the trouble (or even possible for all I know), but I thought it might be neat. I suppose I also wouldn't have a problem with 3 separate LEDs, if this would be more doable.

2. Since this is solid state, would there be any need at all for a "master volume" of some kind? Or any use in leaving the volume pot in the TG layout? This amp will be almost entirely for apartment bedroom use (for now) so I'd like to be able to get okay tones at a low volume. I understand usually the only reason for this is with TUBE amps, so you can get your tubes pushed hard but cut back the volume. I'm guessing just the preamp volume control would be all I need, but I'm certainly no expert.

3. For a power switch, I only need to insert an on-off SPST between the power supply and everything else? I found an SPST with a built in LED indicator, but to do this myself I would need to use a DPDT?

4. I suppose the easiest way to make make the combo also a "head and cab" would be 2 jacks and a patch cable? I've seen where you can make it to where when you plug a jack in, the internal speaker disconnects, but I'd like BOTH. I'm assuming doing this both ways - where the head disconnects when another is plugged in OR when a speaker is plugged in the internal one disconnects - is either too much trouble or not possible? I suppose I would have 3 jacks on the back if I could do this, not sure if that is worth it. haha

5. I don't think I feel like implementing the relay switch, at least for now. I'll add it later if I feel like it. It seems a bit too costly for what it is, not worth it! So should I just wire it like normal, with a 3pdt bypass switch? I can just use a toggle switch on the amp, I'm not THAT lazy. 

Again, some of this may seem overly complicated and over the top, but I am wanting to make this project fancy - mostly so I get to see how/if all of these options and ideas work! I also know that "murphy's law" is basically religion to me, so I may very well be going way more simple on a lot of this. But I looove options!

Please and thanks!! 

[vigilante397]

1 - I had written a fairly lengthy response before remembering it can't be done. Obviously the advantage of a toggle switch is you can physically see which channel you're on, so and LED is unnecessary. I was trying to think if there was a good way to do it with a rotary switch if it was really important (I did something similar on a Dumbloid build with three different tone settings) but I can't see it working with the way that switching works.

2 - Master volume is still necessary in solid state amps as you generally just want to be able to overdrive your preamp without overdriving your power amp.I would probably recommend leaving the volume in the TG layout.

3 - Correct. SPST or SPDT and just leaving one lug empty (SPDTs are just more common). I personally like DPDT and an external LED, I just think it looks classy and I have yet to find a switch with a built-in light that I liked the look of.

4 - Do I understand correctyly that you want the option to use internal speaker + external speaker as well as an option to shut off internal speaker when you plug in an external speaker? Because frankly it seems to me the best option is to have a switch that just shuts off the internal speaker, that way you only need one jack. Want to use both speakers? Piece of cake, just plug in another speaker and leave the switch alone. Want to just use an external speaker? Also piece of cake, plug in your speaker and flip the switch.

5 - A 3PDT toggle wired the same way you would in a pedal would work, but if you don't want an LED for your reverb indicator you can just use a DPDT, because, as we mentioned, with a toggle you can physically see whether it's on or off.

Thinking your way through a million different ideas, whether you actually implement them or not, is good problem-solving practice. It's always good to understand how to do a million things, even if you don't ever plan to do them. When I build amps they're usually fairly simple: single channel, no reverb, usually just gain, bass, treble, and volume. There are plenty of people that need more than that in an amp, but that's enough for me. That being said, The first amp I built had reverb, LEDs lining the cabinet, a switchable dummy load (solid state amps don't care if they have a speaker plugged in or not, but tube amps do!) and a headphone jack with its own independent volume. It didn't take very long to realize I didn't need and didn't use most of these features, so all my builds since have been simpler. But everyone has their own style, and your build can be as extravagant as you have the patience for

[Jebull]

Excellent!!

Totally fine with no channel indicator. Less work! Like you said, the toggle makes it obvious anyway.

So if I leave the volume pot, do I still need the 1u cap that's after it? Or can I just stick the pot on the front?

Ooh yeah that sounds like it would be prefect with the switch for the speaker. Thanks! now to go study switches more. I really need to wrap my head around em better.

Yeah I 100% know I won't end up needing or using half this stuff, but like you said I feel like this is all good exercise! Plus it'll be more fun to show off when I'm done haha. I'm even considering throwing an analog voltmeter in there as that would really nail the look I'm going for.. I've seen a few pedal builders do it and I actually have access to a few where I work, so what the hell? I don't suppose you or anyone would have any tips on this? As far as I understand I would need to wire it in series with the circuit somewhere along with a resistor. Not entirely sure though.

[vigilante397]

I just looked at the schematics again and I don't know what I was thinking, the volume control of the Sunn T preamp will act as the master volume, and the gain is controlled by each channel's gain control. So no you don't need another volume control, and there would be no point in making one.

As for the voltmeter, I've only ever done a digital one that had a 10x LED readout, never done an analog one, so I'm afraid I don't have any experience there. That being said it should be a fairly simple thing to work into the circuit. Do you know the model number of the one you were thinking of putting in? Many (most?) of them have a 600 ohm impedence, so you can take a resistor out of your circuit and add whatever you need to your meter so it adds up to the resistor you took out. Or you can work it into a place where 600 ohms of resistance isn't going to cause a noticeable drop in your signal (maybe after the preamp?). Uncharted territory for me, but you should be able to find a good place with some experimentation (or if someone smarter than me pops in with some advice ).