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Messages - Lex

#16
As I newbie may join this conversation;

  • 5W USB powered with rechargeable internal battery,
  • Full controls;  gain, mid, bass, volume, treble,
  • output 4 to 16 Ohm
  • easy accessible 'effects' board to exchange/combine diodes for the personal taste of sounds with kind of rotary or multi-switch

I base my idea on what I have: small 3W Donner amp for carry on or while sitting on the couch  practicing
For what it is (and the cost of it) it's a very handy piece of hardware. Of course it has limitations but the concept is great and it does sounds 'good' for such a small amp.
When I need 'more' from this amp I connect Zoom G1on/xon ..
An idea to have the best of both worlds in a small package would be great.
+ the process of learning amp / electronic things for ppl like me ..

Cheers

Lex
#17
The Newcomer's Forum / Re: DC output tweak
April 12, 2020, 06:58:12 AM
Thanx all,

did it, nothing fried or melted .. amp works.

BTW:
Always wanted to know but never asked, some cables / adaptors have at the end a plastic cylinder - is this just a joint to change polarity, kind of a mini fuse or just a usability insert to help cable unplug .. or sth else ?

Cheers

Lex
#18
The Newcomer's Forum / Re: DC output tweak
April 11, 2020, 05:21:44 AM
Hello, thanx for answers.

It's Hotone Nano amp, and the other adaptor is from an old Del notebook.

QuoteCurrent is drawn by the load, current is not pushed out of the power supply.   Think about the wall socket in your home  It may have a 15 amp breaker in the service panel, but only the current needed flows.  meaning a 100 watt bulb won't be brighter in a 30A circuit than a 20A circuit.   Your adaptor only needs to have the current you need as a minimum.

Well, now Im think about that , it seems logical.

But would so small class-d board be overload protected  .. ?

If it was old some skool analog thing well I could find the fuse and change it ..

CHeers

Lex
#19
The Newcomer's Forum / DC output tweak
April 10, 2020, 05:00:51 AM
Hello,

I have to test a device but Im without the right adaptor.
Have many adaptors from previous devices so I want to use one.

So I have one idea:
- I have to lower DC output from an adaptor that is 19V 2.5A to 18V 1.5A.

I suppose that I could do it adding one (or more) diode/resistors and placing it on the cable. I have to cut the cable and turn the polarity anyway.

Since I need to drop (only) 1V, I suppose i could use something  like a 5A diode and simply place it in series?
But now Im not sure about dropping current from 2.5A to 1.5A

I'm thinking in the right direction and this is possible to do,
or im just dreaming?

Cheers

Lex
#20
Hi all,
I can't report any progress as I lent this amp to a friend and he is enjoying it like it is.
So I'll be back with more stories .. if I dont sell it to him.
I'm discovering the wonderful world of amp's so I would not be surprised if I just move to something else. (this means more amp's, not less..).
Actually Im quite interested in a vintage Peavey Studio or Bandit .. well will see,
Stray strong all and away of Corona (beer is quite refreshing tho!)
Cheers
Lex
#21
Thanx Phil,

u got a msg back

Cheers
#22
Ok Phil thanx,

still looking for the time to get into it.

Tell me please, that piece of the software is 'Circuit Maker 2000' ?

Could you share with me the 'project' file so I could import after the installation and test / learn / play .. ?

Im still not so familiar with the signs so it will take me weeks figure out

Greetings all and have a good Sunday

#23
The Newcomer's Forum / Re: Some wisdom regarding speakers
February 23, 2020, 05:07:40 AM
Quote from: joecool85 on February 22, 2020, 07:52:42 PM
Quote from: Lex on February 22, 2020, 05:13:16 AM
Thanx all for your reply,

it's obvious .. buy them all, try them all .. and probably keep them all !!!

Cheers

I like the way you think lol.   :tu:

yeah .. have the same with the cars, bikes, ski's .. and probably other stuff

still much cheaper than keeping a women around

#24
The Newcomer's Forum / Re: Some wisdom regarding speakers
February 22, 2020, 05:13:16 AM
Thanx all for your reply,

it's obvious .. buy them all, try them all .. and probably keep them all !!!

Cheers
#25
Hi Phil,

thanx .. im overwhelmed with your reply and need time to read and understand.

Mostly intrigued my the last 2 schematics, as I can see you have changed the positions of 4 diodes / resistors within the circuit ?

So this gives different amplitudes (and the sound as the final output).
What does represent the 1st simulation and what the 2nd in terms of sound?

Regards
#26
The Newcomer's Forum / Re: Some wisdom regarding speakers
February 17, 2020, 08:54:35 AM
Thanx Enzo,

this means: there is no way to be reasonable but to try it all ..

was a bit afraid of that. It's a justification of GAS ...

Cheers
#27
 ok Gent's, thanx again.

I fully understand comments.

Those links are very usable. I need some time to read it and understand it, its not easy.

And yes I agree about the single channel amp.
Im running álso  Laney K30 single ch. keyboard/guitar amp (their first SS amp from 4 decades ago, got it almost unused) and Zoom FX thingy.
The sound is much much better than playing through those 2 small 15W Fenders on 12 inch speaker.
Difference like day and night.
However, tweaking that Champ Squier remains as a challenge to me.

Enzo, yeah that's obvious!
While drawing didn't recognise that solution (not used to draw circuits) but in the real life I think I would see it myself.
Thanx for your comment.


Now the second reply based on Phil's last comments;
Quote
BTW I've just been studying the Schematic for this Amp and it's dawned on me that the output of power chip (pin1) connects to both +&- terminals of the speaker. 
Maybe I've missed something but might be a mistake.
Unfortunately I cant see that on this schematic.
But I suppose it's a weird construction?


Quote
Also regards to the amp distorting even at low volume;
I just simulated the preamp and a 100mV signal at input does not distort until you turn up past halfway.
But I notice the FB resistor around power chip is 130k. :loco
surely that is rather high and I'm guessing would distort even at low gain. (And that was the main reason for *Lex's* initial post)
The schematic is not very clear and I can't read the part number on the power chip.

Out from my curiosity, how do you simulate a pre-amp ?
Some software where you put and connect all the components and then observe amplitudes .. ? (cant imagine sound)

And yes there is a slight distortion on the clean channel, in combination with a 'flat' sound.
Second Gain pot all the way turned to 0.
I did not drive this amp more than 1.5-2 on the volume pot.

If you could point to this 'power chip' so I know where and what is it, then I could make some tweaks in the photoshop to get more clear reading of schematic?

Im enjoying emojis too, they are great !!!

Greetings
#28
The Newcomer's Forum / Some wisdom regarding speakers
February 16, 2020, 09:09:41 AM


Any worth of getting used 10 inch speakers from old Peavey Backstage (late '70, CST), so called 'squareback' for an external cab?
I mean, Im 'educating' my self and trying many things just to understand what Im hearing (and why of course).
It brings (un)necessary costs with it.

So, would I be just better to go for a new modern speaker(s) or take a risk and spend less money (about 1/3 of the price of the new one) for my 'tests'?

Im I reasonable ..?

Greetings
#29
Phil & Joe thanx,

the purpose of re-building this old cheap Champ amp is purely to learn, understand and improve the sound and my knowlegde, if possible. 
Im re-entering music again after many years.
This time Im gonna learn to understand and not just interpret someone elses music. Or gear..

While drawing I did not pay attention to the polarity of diodes as Im not used on their graphical appearance.
But I do assume that all diodes should be wired in the same way, probably positive (+) as input and negative (-) as output.
I think this was a wrong assumption now.

So this explains where I made a mistake:

Quote" wiring back to back in the loop" and
  + -
<     >
  - +

I have attached changed polarity for S1 section of diodes, I hope I understood your comments gent's,

Thanx

Greetings
#30
Hi all,

got carried away with this thought about multiple diodes and after some brainstorming I made a simple schematic (according to my knowledge based on auto-moto electronics) .. with some on-line schematics tool.

I would like to hear if my thinking is logical or not.

CR 1 & 2 are removed, there comes a socket (J1 & 2),
2 x switches (S1 & 2),
repeating diodes D1 - D10

Greetings