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Messages - Oooscar

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Just to share with you...

I have tried the g1xOn with a generic TDA7297 stereo amp board bought on eBay, and I can get louder volumes without the squeal... (I am bit experimental... But it seems you can get nice volume and sound in a cheap DIY way) I have been told as well that cheap pickup coils can also contribute to produce that squeal, due to microphonic effects. Wax potted ones have less microphonic effect. In the future I will try better pickups also.

Yes... Well, I learned today that the g1xon has different level controls, one of them, the master level can make a difference. I will keep trying. Maybe I can use my nice diy amp after all...

I have tried with a different lm386 amp that I have with volume control, and at some point starts to happen. I also have tried disconnecting the pins 1 and 8 of the amp of the photograph, and the problem still remains at some point. I noticed that when I touched the strings with my hand the squeal disappears, but when I touch the strings with some fabric, textile, for instance, the squeal does not vanish.

The other road to go is buying some device. I would prefer not to do it, or buying something economical.

The idea for this small amp was to make it as simple as possible, and to get the maximum of it. So I decided to control the volume with the guitar volume control, and the gain of the LM386 is set to maximum. Pins 1 and 8 are connected together with a wire, like in a smokey amp. Some of the patches give me more trouble than others, but in general, as soon as I crank up the volume control of the guitar, the squeal comes in. I would like to get still a nice volume to fill the room,  ;)

Preamps and Effects / Zoom g1xon and diy guitar amp based on lm386
« on: June 24, 2020, 08:27:56 AM »
Hello all,

Recently I bought a Zoom G1xon effects processor, and I am trying it with a homemade amp I did based on an LM386 ic. I didn't expect to work properly. What happens is that any guitar I connect to the g1xon and to the amp produced in general a lot of noise, and if I turn the volume of the guitar up, a high pitch squeal, like feedback sound starts to sound. Have you had these sort of sounds in any unwanted situation? Maybe I can get some tips to solve it. The amp by itself with just a guitar works well, with a bit of hum of course, but fine. I attach a photograph of the diy amp.

The Newcomer's Forum / Re: Tda ICs Pentawatt PCB
« on: May 29, 2020, 04:14:06 PM »
I see, thanks a lot... I have read about mica washers. The idea is to use a washer that transfers well the heat but not the electricity. Usually, go together both properties. The reason to do that is to avoid kind of antennae effects? I have not thought in those issues. Sorry... Too many questions...

About the heatsink, I have a piece of solid metal from a car radio, this piece is one the sides of the whole radio. Pretty impressive heatsink.

The Newcomer's Forum / Re: Tda ICs Pentawatt PCB
« on: May 29, 2020, 06:59:43 AM »
Thanks a lot...  :tu: About the heatsinks, do you think any piece/sheet of metal will do the job, or it is worth to use a proper one. Aluminum or denser... ?

The Newcomer's Forum / Tda ICs Pentawatt PCB
« on: May 28, 2020, 04:29:39 PM »

I have some TDA ICs, 2030A, 2003, 2006. The Pentawatt package pins do not fit on a typical perforated board. Is there some specific socket to use it with a perforated board? Otherwise I have to make bigger holes. Any suggestion? Maybe some of you have more experience.

Another question. I heard that Jfets with low pinch off voltage are better to use them as buffers, boosters? I guess it affects to the clipping, taking into account that a guitar signal has 200 mV peak to peak, let's say.



The Newcomer's Forum / Preamp stages, clipping and tone control.
« on: May 11, 2020, 10:47:11 AM »

I am studying different preamp schematics. I am inclined to minimal amps or amps with not so many parts, just the ones needed to produce a given sound for guitar practice/bedroom playing purposes. I have several questions:

1.- Is it good to add a boost stage initially before any overdrive/soft clipping in terms of sound?
2.- Is it better to add a tone control stack before any clipping or after, in terms of sound?
Let's say you make: guitar, boost, tone control/tone stack, soft and/or hard clipping, out.
3.- Does it worth to add a classic tone stack with bass, trebble, mid respect a single pot tone control, or a BMP with some mid control (Jack Orman mod I believe...)?

It seems to me that with a simple tone control (or maybe two pots) you can get a wide range of sounds, but I am learning, and I would like to understand how many stages can have a guitar amp, and the purpose of those, to see how can I simplify or minimize them, and still get a good and wide range of sound. For instance, adding preamp stages to an LM386 can give you a good sound with control. I have tried hard clip diodes with a TL072, and the sound to me gets better. Nicer.

Thank you very much for your attention.

Regards, cheers.

Amplifier Discussion / Re: Official SSGuitar kit, on-board options
« on: April 24, 2020, 11:19:09 AM »
Looking forward for the schematic...

Here it is.

The first issue is solved. I added a 100n capacitor to isolate the filter from the dc of the second op amp as well, and it seems to work.

The second issue with the JRC386D remains. The picture shows both schematics.


I am starting to experiment with opamps as preamps, and/or headphone amps.
I am trying to add a tone control, and the big muff pi seems a simple one. I put it between the two op amps of a TL072CP but the sound I get is very bad. When there is not tone control, I get at least a clean sound when I listen with my headphones, but when I introduce the big muff pi tone control, the sound is noisy/distorted (in a unpleasant way). What I am looking for is a clean and filtered sound. If I want musical distortion I will add it later. But just to go step by step.

I have tried also to add the big muff pi passive tone control to the output of a JRC386D simple circuit, with just a capacitor at the output, and I get no sound at all. I am thinking if the output current of the opamp is not enough for the tone control circuit. When I remove it, I get sound in my headphones. I know that there is a circuit called Smash Drive that has a tone stack in the output of a LM386, but it is used as a pedal, and I have no tried and don't know if it has enough power the signal to drive headphones.

I am trying things with ingenuity, just step by step. Maybe some of you here have tried the same circuits or similar ones, or have more knowledge, and can give me some clues to help me get those circuits work.



The Newcomer's Forum / Re: TDA2030A based amp
« on: April 13, 2020, 08:16:15 AM »
Interesting. I bought one TDA2030A recently. Which is a good and not very expensive way to power it? That's the first thing, and I am afraid that 12 v and 1 A max. is not enough.




I voted for other, because it would be nice to have a combination of both as well. The schematic could cover preamp with tone stack on one side and tone control on the other side, and then, even if the PCB has to be for one of the options. I am going towards a practice amp, making it each time more complete. Now, I am starting with op amps. I saw a project on the forum with a PAM8403. And it sounds good.

Anyway, nice idea.


Amplifier Discussion / Re: Feng - Mini Amp using PAM8403 (2x 3 Watt)
« on: April 07, 2020, 03:59:57 AM »
This project looks interesting. The schematic shows more components than a typical op amp preamp. I am not taking into account the tone stack. Could it be simplified? For instance, could the 220 resistor be removed? Which function does it have?

Thank you very much.

P.S. That's my first post, btw.

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