planning to build car sub amp, help needed

[navin]

Originally Posted by s0uljah

Off Topic, nevertheless I saw some Burr Brown DAC's lying in an electronics shop at SP Road the other day... is it a necessity for building an amp?

DAC for an amp?

as far as high voltage needed one can build a SMPS today no need for step up transformers etc...

here is a link to start with

diyAudio Forums - Making car amplifier SMPS with tl494 + DC Protection

[tsk1979]

Hey clipto which market is it??
I wish there was one in Delhi which did that!
Is such a market there in Ludhiana too, or are you talking about Jalandhar?

[navin]

Originally Posted by Sutra

I am big fan of Hitachi Mosfets, the popular design around this matching pair was Crescendo and Mini Crescendo, could not locate these for long time, last i checked on Lamington Road it was Rs750/- a pair, too steep.

Those must the the pastic packaging. THe Metal boxes cost a bit more.
BTW the Cresendo etc.. are not really worht the effort. I would at designs from companies like B&K. Google might help. I have not dont this sort of work for a while.

OT: Sutra, It is nice to have someone who is knowledgable about DIY here. We wish you contribute more.

[clipto333]

Originally Posted by tsk1979

Hey clipto which market is it??
I wish there was one in Delhi which did that!
Is such a market there in Ludhiana too, or are you talking about Jalandhar?

hi,

the market is called phagwara gate, its in jalandhar. there's also another market for heavy gauge wires and elecrtical stuff. i dont know anything about ludhiana.

do you need any stuff? if you want i can find out. and i have no problem doing that. also ill courier the stuff. so just let me know if i can help you in any way.

can anyone let me know if there are any good quality indian drivers. or how much do the good ones cost approx? eg. scan, vifa \. please let me know guys.
thanks

rishabh

[tsk1979]

Thanks clipto.
What I am looking for now involves a 2.5mm stereo Plug, wire, 2 push button switches and 1 DPST switch.
Will let you know if I need anything.
Can you let me know the location of the market while coming from LDH?

Don't reply on this thread lets not go offtopic, send me a PM

[clipto333]

hi

bhai i need to know about drivers availabilty. how does bolton fair?
please help me out on this so i can decide.

[clipto333]

Originally Posted by tsk1979

The other problem is availability of analysis equipment. In college I had oscilloscopes to see wether it turned out right or wrong. If I assembled an amp today I wouldn't know where it went wrong.

hi,

what kind of oscilloscopes are suitable for amps? i will definitely buy one. how much do they cost?

thanks

rishabh

[clipto333]

hi,

decided to build a chip amp using lm3886. can anyone send me a schematic which you think i s good. im lookin for 50 w rms per ch and need 2 ch. also i have 6 ohm speakers. and what kind of psu do i need. specs would hep.

thanks
rishabh

100th post i guess.

[low_bass_makker]

if you are going for a 50 w rms amp then it would be a home audio amp....and not a sub amp....and since it is a not a sub amp you are going to use it at home....so then power supply would not be a issue....you can use a setupdown transformer to power you amp....with a simple bridge rectifier with a small capacitor bank to clean it out.....

[Sam Kapasi]

Originally Posted by low_bass_makker

to achive higher wattages firstly one will have to make the DC-DC power supply which is a challange itself as one would be requiring more than 24-0-24 volts to power an amp which would be making more than 400 rms...so it will be hard time ahead clip dont get dishearted we all are here to help you.....

I could not agree more. It is easier to build a power amplifier, once you have the power supply all sorted out.
When you build an amplifier for home, you take the input power for granted.

Keeping it simple:
We have 230V/50Hz/15A (current approx) on tap. All we need to do is get a suitable step down transformer (preferably toroidal), build a decent recitifier (using bridge diodes and the ilk) and a nice capacitance bank (10,000 mfd+) and your power supply is ready.
Alternatively, you can even use a X-0-X transformer and build a centre ground +/- supply for use with push pull circuits.

Now comes the car supply:
You have 12Vdc/30A (current approx) on tap. That means in most cases you will need to step up the voltage. Also, the question of transformer coupling becomes difficult as the voltage is already in DC (transformers only work on AC)
Hence you need to CHOP up the dc voltage, regenerate AC out of it, step it up etc.
Building a chopper step up power supply is far more complicated than a transformer based AC-DC step down supply. Also requires certain components for accuracy (Most standard car amplifier supplies use opto-couplers, standard BJTs, FETS and gates like theyre going out of style) which may not be that easily available. Also building of chopper transformers requires precise (read:deadly) accuracy.

Building a 12Vdc power supply, that runs a power amplifier that can drive 400W is not something for the faint of heart. I do not say it is impossible, but I suspect that for most average DIYers, it's a morsel that may turn out to be difficult to chew.

[navin]

clipto. no need for 3 seperate posts. you can edit your posts for 15 min.
a) did you get a pair of 6" drivers Sam was offering for free?
b) Bolton are past their prime but if you are really interested see if you can find anything made by Peerless India. Post us a pic and we can try and help you from there. Philips makes a decent dome tweeter too. If you have a bigger budget try Corrson in Bangalore.
c) There are plently of 3886 based ckts out there. So many that it can confuse you. You'd need atleast a 300VA PSU for a 50W x 2 / 6ohms amp. I forget is this a car amp or a home amp?

[tsk1979]

@Sam - Can't a simple DC DC boost converter do the job?
A circuit can be created with this IC.
MAX1932 Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply

We had to make such circuits to pass our exams.
DC-DC Converter Tutorial - Maxim/Dallas

If you buy off the shelf a 12V-24V DC-DC converter costs around 50-100$ in the US.

[Sam Kapasi]

Originally Posted by tsk1979

If you buy off the shelf a 12V-24V DC-DC converter costs around 50-100$ in the US.

A simple 12V-24V dc convertor is very far from the answer.

We need a high current 48V upto 120V or even more(depending on design) +/- dc power supply to power todays power transistors.

[low_bass_makker]

Originally Posted by Sam Kapasi

We need a high current 48V upto 120V or even more(depending on design) +/- dc power supply to power todays power transistors.

I agree here.....


Clip so what are you planning to do a home audio or a car audio.....

[navin]

At +/- 36V the LM3886 and the LM3875 will produce about 60W see XLS file

http://www.national.com/appinfo/audi...gn_Guide14.xls

this will help you if you are interested in the LM3886

diyAudio Forums - LM3886 car clone

diyAudio Forums - LM3886 macro model ?

diyAudio Forums - LM4780 kit vs ready car amplifier

diyAudio Forums - Want to build car amp to run a couple of 12" subs

and for a sampler on SMPS
Switchmode Power Supply For Car Audio

diyAudio Forums - S.m.p.s

diyAudio Forums - SMPS 12VDC to +-45VDC

I'lll trust google will help you further.