C3=10μF and no pin7-5 circuit at all.

Shall we say this is FINAL?

(at least for today?)

EDIT: 1st Schematic removed as not correct and all relevant discussion, from this post.

--

I am posting three designs I found in case anyone would care to comment on their pros and cons. I would n't mind the passive design and the loss of treble, I'm not a pro musician, so I do not really care. Nevertheles, these 3 are definitely beyond my building capabilities.  

Thank you!

Quote from: J M Fahey on October 29, 2011, 02:25:13 PM

Δημήτριος would be Dimitrios

Παναγιωτίδης would be Panationis

του this one beats me

Γεωργίου would be Georgiou

..........
close enough?

You got 3 our of 4, that's impressive!

The "του" word is a declension of the singular form of the masculine article, in the genitive case (i.e. possesive). It basically means "of the". Thus my name is: 1st name Dimitrios (meaning, I was named after the Christian orthodox Saint Dimitrios), 2nd name Panagiotidis (that's my family name which -simplified- means the decendants of Panagioti who was my great-great grand father) and 3rd name (of the) Georgios (meaning that my father's 1st name is Georgios). According to Greek culture we name our children after their grand father/mother's names, which -you guessed- creates ever more complicated combinations.

I agree about the external quality or the greek women, and I am with you 100% on their pointless and futile desire to look less "Hellenic" and more American. But what can you do? Nothing... Can't live with can't live without them. Luckily, for the time being I am taking a hiatus from Greek women. Living in the US -definitely- gives one the advantage to be ethnically more ...selective.

--

BTW, any comments on the modified schematic? Let's not forget what we're here for eh!  8|

'Till later!   

Hello again!

The attached PDF is something I -with my limited knowledge- find as a viable better alternative to just a Y-cord (which should work but is NOT the ideal solution) especially since even I can build it with minimal effort and actually I could even attempt to integrate inside the entire chassis.

I did find some other more sophisticated designs based around the TL074 or similar but I would like to try something within my technical reach first.

Please let me know what you think.

Thank you!

Hola Juan, muy encantado de conocerte! Cómo está el tiempo hoy en Argentina?

Well, I won't attempt any more of my broken Spanish, all I know is from the guys I play fútbol with.

I am pleasantly surprised that you have visited my country, especially because after landing in Athens, most people "hit" the beaches and the bars/night-life in the islands. But you -instead- went into a bookstore and then a bakery shop. And as much as I can understand the bakery (cuando viajas te da hambre y tengo que comer, no?) shopping for a copy of Antoine de Saint Exupery's "The little Prince" is definitely remarkable!

Modern Greek (or Hellenic as is the proper term) is the direct descendant of Ancient Greek, simplified and adapted to people's ever-changing needs over the last 2,500 years. Still it is a language that is -according to my favorite saying- unnecessarily complicated, definitely not for the fainted at heart. However your approach makes a lot of sense and speaking a latin based language yourself clearly gives you an advantage. The only simple thing about Greek is that we say what we read and we write exactly as we say it. Sounds and letters do not change between words, i.e. like in English. One other thing is that Greek and Spanish have pretty much the same sounds that -say- Americans are not used to. My soccer buddies make fun of me when we play because when I get mad I start yelling at them in Spanish and actually my accent changes depending who I am yelling at. :grr  I play goalie, (y porteros suelen ser locos) so I get to yell at them a lot, you get the picture :duh  

OK, I am grossly abusing the terms of this forum. So back to business, I read your post, here's my take:

1. I am skipping the "grit" switch but keeping the variable R and C between pins 1-8 to adjust my gain and keep it scratch free. I am posting a modified schematic. Please comment if you see any mistakes.

2. I would have never thought using the speaker output itself to do such modulation can a Tremolo effect. WOW!

3. I heard the YT samples and I was blown away! If appears that a great amp will sound bad through a small/cheap speaker, while a basic amp will sound OK via, if not good enough, via a nice 4x12" cabinet.

4. In Greek the book you were looking for is "Ο Μικρός Πρίγκηπας" (o Mikrós Prínkipas) and the bread you asked for was not pizza but probably some kind of "πίττα" meaning some kind of variation of the famous "pitta" bread widely found in in the USA in those fast-food places selling gyros. BTW, "γύρος",  means when something goes around completing full 360 degree revolutions. You've seen how they cook "gyros", right?

5. I still have not made the connection why you are "torturing" yourself with learning Chinese but since I cannot help you with that I can only wish you "good luck", I admire you! If you ever want to brush-up on your Greek, you know who's your tutor gonna be! :tu:

Ηasta la próxima vez!

--
Δημήτριος Παναγιωτίδης του Γεωργίου
PS: Τhat's my full name, so now you know why the abbreviated Dimi Pana

Hello JMF -

Thank you for the long explanations, most of that is obviously way above me, but I was able to follow your reasoning.

I tend to be fast when I get infatuated with something, that is my shortcoming, I need to learn to curb my over-enthusiasm. I realize I have agitated you, and I apologize for that.

Regarding the NC, I have collected all the parts and I will build it as is. I want to hear how it will sound into a bigger cabinet. Eventually though I think I will try a non "grit" version, exactly per your advice. It sounds like for such a simple design a Volume and Gain control should yield a sufficient range of clean and "dirty" sound.

So, if I decide to NOT use the "grit" switch do I just remove SW2, jumper the gap, and leave everything else as is, or do I remove C4 and C3 as well?

--

I would have never attempted to learn Chinese, so -really- I admire your courage. I speak decent English, average French, basic Spanish and Italian. I can "fake it" in German as long as I keep my responses to an absolute minimum .  Finally, I am fluent in Hellenic since I was born and bred in Athens, Greece.

Best regards!

Τhanks for your reply, Joe. I now understand the pin 1-8 configuration and any additions (or not) to it.

I am building this with Volume + Gain + Tone controls, I just wish it did not have the "grit" switch.

From what I have read, "grit" switch augments the distortion. E.g. with this switch OFF the the gain control will still produce distortion, turn it ON and you get more body in the distortion. Perhaps you can put it in better more electronically correct terms.

Anyway, if anyone else cares to answer queston #1 and #2, it would be greatly appreciated.

As far as JMF, I am highly appreciative for all of his advice to date and -hopefully- in the future. I am not offended at all, on the contrary, I am concerned about myself NOT to offend anybody. My first language is not English either.  :tu:

Thank you all!

Sorry, but all of a sudden I do NOT feel welcome anymore.

When I registered in this forum it did not state anywhere that the minimum requirement should be electronics knowledge higher than 101. How am I supposed to know which of my questions is above or below level 101 if I have never taken the 101 class? I never said or even implied that I am an expert, on the contrary. When I see a schematic like the NC (noisy cricket) I can identify all the components but I am not 100% sure why they are there and what exactly they do.

Yes, I want to learn BUT NOT at the expense of your time or whatever. So, since I am not afraid to use a solder gun, if I am given CLEAR instructions and non-conflicting advice I can build a circuit as simple as this. I guess, my response is, if you find my questions TOO basic, by all means PLEASE do not bother answering them. Perhaps, a few others more experienced than me but definitely less knowledgeable than you, will chose to "waste" some of their time to do so. I personally, never took this forum for granted, sharing is caring, YES, still no one forces any one to do anything, right?

I do fall under the description of a " ... *regular* musician who has developed an interest on how Electronics they use work, etc..." however with all due respect it is not fair to be treated like the village idiot because I have never taken -YET- a 101 electronics class. I am a foreign graduate student at UI of Chicago in Information Technology Management and I tutor younger students on Math, Computers, etc. What do you think will happen, if my students asked me a basic question and I told them to go -first- take the 101 class?   

So, what do you want me to do? Keep posting or basically "get the heck out" until I have a better understanding of 101 electronics? I mean this is basically what your message is Mr. JM Fahey, and I am sorry if you feel I imposed on you and the rest of the members. That was not my intention. However, knowing myself, you will be surprised how fast I learn, with the right teacher, so if you stick with me now, I will be soon asking more challenging questions. If not, we're still friends...

In all fairness if you all go back in this thread, to previously posted messages, you will notice some conflicting advice and comments from various members that contradict each other or -especially- what the datasheet is saying. Yes, I did read the datasheet and understood most of it. I am assuming the datasheet is right, right?

Also, as matter or fact in JMF's last message paragraphs #1 and #2 state two exactly opposite positions. How am I to respond to that? If I say I agree, I am basically excluding myself from this discussion and I should probably un-register. If I say I disagree, I am being ungrateful to ALL this great feedback JMF already gave me. I am sorry, this is getting unnecessarily complicated, I just can't comprehend where this is coming from. Did I say something to offend you? If I did, I apologize.

-

Now to the original point, there is some confusion (at least to me) as to:

1) What exactly C3 is doing attached to pin-7 then going to ground (if pin-7 is a bypass), what is its optimal value and WHY?

2) Pin-7 is also connecting to pin-5 via the "grit" switch and C4. But, what will the effect be trying different C4 values?

3) Finally, is an extra capacitor -indeed- needed across pins 1-8 as the datasheet suggests (and as a matter of fact in series with a resistor) or NOT, and WHY? If you say YES, what are the optimal R, C values and WHY?


--
Thank you very much!

PS: I am attaching the PDF I am following for building the NC.

Quote from: DartPlayer170 on October 26, 2011, 05:41:53 PM
Your last statement is not correct. You can hook up a 4 ohm or an 8 ohm speaker to the 2030A.
You can replace the wall-wart to a 20W ( more would be a waste since the 2030A cannot handle it ).
The problem is to figure out how high of a voltage to get for the wall-wart.
There are two problems:
1 - the rating on the wall-wart is nominal. It may be more than the rating even at full load.
2 - the current drain of the 2030A is dependent on the supply voltage, the load and the input signal. And hence, so is the power dissipation.

The 2030A is rated for 44V max and 20W max. However, the current is dependent on the load. If you use a 4 ohm speaker then a 34V supply will dissipate 20W. I=P/V so the current is about 600mA.

What I can tell you is that I have replaced the wall-wart with a 24V 600mA and it works fine.

If you want to create a cleaner sound with the gain at 0, then you need to decrease the gain in the first stage of the amp. The designers set it too high. The clipping diodes that you were told to remove begin distorting the signal at about 800mVpp. You could just remove these diodes as suggested ( d1 and d2 ) if you don`t want to be able to use the distortion circuit. Another solution is to increase the negative feedback to the stage 1 amp. This can be achieved by replacing the feedback resistor with a higher value. The feedback resistor is in series with an electrolytic capacitor between either pin 2 or 6 ( depending on which one they are using as stage 1 ) of the JRC4558D and ground.

Alright, now I am lost...

1. Regarding the power supply: My intention is to hook this up to a 8Ω cabinet. So, are you saying that the original wall-wart will not be enough? If this is correct then, what are the specs for the proper PSU?

2. I thought phatt's advice about removing the diodes meant the gain pot is still working and you still get some distortion, you just get less distortion or "cleaner" distortion. However, from your last post, if I understand right, are you saying the gain pot becomes inactive and you basically lose ALL distortion this thing can produce? If that's the case, then no this is not what I am after. I do want the versatility of having a Gain control before my Volume. Question is can this Gain control be more gradual in response and smoother in performance?  

3. The 24V 600mA wall-wart powers your MA007 right? Are you using it as is or you modified it and play it through a different speaker?

Is this the MA007 ? Is it made of plastic? I'd be curious how it sounds!?!

Thanks!

Quote from: J M Fahey on October 26, 2011, 05:25:42 PM
Fact is, LM386 was designed with *extreme* simplicity in mind.
So much so, that it includes the gain setting negative feedback resistors.
To provide you an option, one of them is connected between pins and 8.
Open: "normal" gain, good for most uses.
Shorted: quite a lot more.
But there is some DC voltage betwen those pins, so if you add a pot there to vary the gain, you need a cap in series with it or it will scratch.
If you add a gain switch, it will pop when activated.
If the connection is fixed, no problem, can use or not the 10uF cap at will.
a 100nF cap is too small and, best case, will work as a bright control.

In my case, the 386 being simple is good.

So since I do want a Gain control, do I follow the NC design exactly or do I add the extra 10μF cap in series with the variable resistor between pins 1 - 8? And what designation do we give that cap so I do not confuse it with C3. And what is the purpose of C3

Thanks!

Quote from: joecool85 on October 26, 2011, 02:01:22 PM

Quote from: Dimi Pana on October 25, 2011, 05:39:16 PM
Also, when jumpering pins 1 and 8 of the LM368, should n't a capacitor be in there as well? I read somewhere about this but unfortunately do not remember any specifics.

On all three LM386 amps I've built I jumpered 1 and 8 directly, no cap or resistor.

OK, I am getting a little confused, but that's normal for a novice, right?

So, the LM386N-1 datasheet http://www.national.com/ds/LM/LM386.pdf says:

"With pins 1 and 8 open
the 1.35 kΩ resistor sets the gain at 20 (26 dB). If a capacitor
is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the
gain will go up to 200 (46 dB). If a resistor is placed in series
with the capacitor, the gain can be set to any value from 20
to 200."

First the 1.35 kΩ resistor from the datasheet, where is it on the NC schematic?

Second, regarding the pin1-8 gain thing, what is the difference between the two approaches? What are the benefits or simply the rational behind each design?

I guess if I want max gain without a gain pot I do it like you Joe, otherwise if I want to vary the gain from 20 to 200 then the original NoisyCricket design is correct right? But there is no capacitor in the NoisyCricket. So what's going on?

Also, that C3 cap is connected to pin 7 which is labeled as "bypass". Bypass, of what? The way I see it pin 7 is also connected to pin 5 (Vout) via the the "grit" switch and C4. I mean pin 7 is there for a reason, so why is it labeled "bypass".

So that C3 what is it doing there and is the NC value correct or should it be changed to 100nF instead of 10μF and why?

Thanks!

Quote from: joecool85 on October 26, 2011, 02:03:10 PM
Quick answer:

You can split it with a Y cable, but it is better to do it with an electronic splitter circuit using a TL074 or similar.

Thank you Joe, I searched google using keywords "TL074 guitar signal splitter" and found some interesting results, I will "weed" through them and re-post with more info/questions if needed.

Thank you very much for all your help so far! 

So are you guys saying that with the original FirstAct wall-wart, or even a slightly better one, I mean with more milliamperes, this amp is pretty much "doomed" anyway to an output of (no more than) ~5 watts into a 4Ω speaker? This is not necessarily bad, I am not really looking for more power, but for a cleaner and more usable (thus musical) sound.

My intention originally was to hook it up to a 8Ω self-made cabinet and if I can scrounge a couple of speakers, perhaps build it as a 2x8" or 2x10" depending on the price I get. I mean who would n't want a 4x12" but in this case I think (lol) this might be overkill ...

So unless I can attach a real power supply to this toy-amp, are you saying my output should "see" a 4Ω speaker, anything else and I will probably blow the TDA2030A up?

Is this a correct statement?

Thanks again for your comments!   

Quote from: J M Fahey on February 03, 2011, 10:58:44 PM
Well, with no volume and minimum gain, what's the DC voltage on LM386 pins   6 and 5?
What's Q1 (Fet) source voltage?
In that schematic, C3 should be 10uF and don't know what C4 is supposed to do.
I would not use it at all.

Hello, JMF !!!

Are you absolutely sure this C3 should be 10μF instead of 100nF ? What is the reasoning behind that? I am not questioning your input -on the contrary- I am just curious why, just want to learn.

Also, when jumpering pins 1 and 8 of the LM368, should n't a capacitor be in there as well? I read somewhere about this but unfortunately do not remember any specifics.

Thank you!

OK, I know the subject of my topic is unusual, to say the least. I will also admit that I am a noob and I know little about electronics, well just a few basics. I also looked up as best as I could into previous topics and could not find something similar.

So ... my apologies if what I will say makes no sense or is not doable. Also, sorry if this has been covered elsewhere.

Here it goes:

I am currently building my first DIY amp using this design --> http://beavisaudio.com/projects/NoisyCricket .

I used a Radio Shack board (see attached PDF) to build it thus I build two side by side.

These little amps are so easy to build, cost is very low, and each puts out no more than 1W of power. I tried both through an 8" speaker, and I also intend to build a 2x8" cabinet later.

--

I also have an old DOD multi effects unit (3 dimension) which has separate L and R input and output jacks.

I did some measurements and the dual-amp PCB can fit inside the DOD chassis, with all necessary in/out jacks and pots drilled on the DOD faceplate and backplate (after some creative artwork of course).

So ...  here's what I'd like to do IF possible:

Take my guitar's signal, split it in two, send one "half" to L and the other "half" to R input of the DOD, then take each output from the DOD (L and R) and send one to one amp and the other to the other amp. Finally, each amp drives each own speaker within the same cabinet. The DOD chassis will be mounted on top of the cabinet (slide-in, removable) and this whole contraption should measure about (18x22x8)" (HxWxL). Hopefully, it will sound OK. Not necessarily great but OK. I am not a professional musician, just for practice, jamming with friends and playing at (not-so-loud) parties.

-

So, are you still with me or looking for something to ...throw at me? (lol) (sorry, my jokes, as well my gadget ideas are lousy).

--

If you are still here, now it's time for some questions:

1. What is the best way to split the guitar signal in two equal/identical parts? Y-cord? Audio Mixer? small DIY circuit?

2. The DOD does not have separate volume controls for its L and R outputs. Therefore it makes sense to keep the amp controls separated too, having a L and a R side on my amp not only will look cool, but it can be practically useful to control how much/what effect goes to each side.

3. Since this simple amp design does not have FX in/out, what signal path is best?

a) Guitar to DOD to amp to speakers? (But how would this sound? Is n't it a wrong idea to insert your FX before the preamp?)

or

b) Guitar to amp to DOD to speakers? (would that work? I mean can the DOD drive the speakers? I do not think so).

c) If both a) and b) are not ideal, can anyone suggest if and how I can mod this little amp in order to use the FX unit?

--

So take your time, let me know if all this is possible or not. I understand it might not be worth the time or the money, and yes I agree, I do not intend to spend a lot of (more) money on it, but time, that I got, (no I'm not in jail) especially if this is going to be a fun project.

Thank you all so very much,

Cheers!