LME49811 as a guitar amp.

[CorySCline]

Hello all!

I have recently completed a small guitar amp based off the LM386N-4 IC and am rather proud of it . However, I only built it as a proof of concept. More so, proof that I could have the dedication to learn such a field. My true goal is to build a stage quality amp. I am looking for a forum that would be willing to guide me through my stages of learning . I hope this community will be willing to help (2 others have refused to help essentially saying that my current lack of knowledge means I can never learn to do what I want). I will admit, I am definitely in the learning stages, so please understand I may ask stupid questions. Anyways, introductions aside, onto my current goal!

As previously stated, I wish to make a LOUD stage amplifier. I have been considering using the LME49811. Looking at the example circuit in the datasheet, I understand (for the most part) how to modify it too my needs. The parts I don't know I will worry about as I get there. The current issue that I am having is this. The example circuit calls for a 20V~100V operating voltage range with a max of 200V. it outputs a current of 9mA. I wish to put together my own power supply (This seems to get people laughing at me for some reason...is wanting to learn how bad?) I have looked around for days, but can't find a detailed enough resource that can teach me the math involved in choosing a transformer, rectifier, smoother, or regulator. How can I go about learning this? Also, just to be sure, the 20V~100V means any voltage between those values will be safe to drive it, correct?

Thanks in advance if this community will be willing to accept me for my current noobness.

[CorySCline]

No love for me? lol....jk I can be patient

[preiter]

There's nothing special about the amplifier in a guitar amp, except perhaps a need for more robust cooling.

[CorySCline]

Originally Posted by preiter

There's nothing special about the amplifier in a guitar amp, except perhaps a need for more robust cooling.

Thank you for the reply I have considered incorporating some sort of PC style liquid cooling...mostly for bragging rights...I mean..why not? lol. However, I would prefer to start another thread about that when I'm ready .

For now, my concern is about designing my power supply . Any tips on that?

Thanks!

[AndrewT]

There are three kinds of amplifier.
a.) One to reproduce the creations of others.
b.) One to help create those sounds the musician wants him/herself or us to hear.
c.) One that is specified PMPO.

I think you need type b.
This is quite different from type a. & from type c.

I suggest you move this to musical instruments.

BTW,
192 is insignificant on this Forum.

[sreten]

Hi,

Its +/- 20V to +/- 100V you need. 9mA is the maximum current drive
to the output devices, your power supply will need far more current.

It is inevitable with beginners attempting to make large powerful
amplifiers the thing will blow up at some point, and as a high power
device may well qualify as dangerous if not built to proper standards.

http://www.national.com/an/AN/AN-1849.pdf details a high power supply.

The amplifier in the chip spec sheet is a bit of a joke and barely scratches
the issues of proper amplifier design, it just states you need a "properly"
designed output stage for high output, far easier said than done.

http://www.national.com/an/AN/AN-1850.pdf is a lot more useful.

Its far better to buy a suitable (used ?) instrument amplifier that sounds
good (to you) with all the facilities you will ever need, and then pondering
the service manual for as long as it takes to understand how it all works
and how and why its put together the way it is. Its not simple.

rgds, sreten.

[CorySCline]

Well then, I shall move on and give up on what I wish to do then? I understand the difficulty, and have been coming to the conclusion that the LME49811 is not for me. But I still wish to make something more powerful than the LM386N-4. Any recommendations?

[CorySCline]

I appreciate all the advice.

@sreten: having a device is not te problem, I have quite a few. I simply want to learn. However, you are right, I am probably shooting too high.

[AndrewT]

Don't give up.
Do the research, expand your knowledge.
Build/buy what you need.

[panson_hk]

why don't start with something easier - a chipamp such as LM3886, TDA7294.