beginner amp, 100?

[easyrider]

hay everybody, im new round here,

anyways im looking to build my first amp and am looking for some help or guidence from you guys.

im after an amp which has 100W per channel.

umm...

dont mind about briging, or parralell stuff.

umm... it must have a parts list, i can't work it out from a schmatic yet


anyway thanks in advance for anyone who is willing to help or point me in the right direction.



easy rider.


p.s

i have searched without any luck, maybe im looking for the wrong things.

 

[ronc]

First question is why do you need 100 watts?
ron

 

[ir]

possibly used to 'rubbish' brand name stuff (AIWA, Sony, Philips)?

thus isn't aware that even 15W is TOO loud for the average room (thru good speakers)

 

[ronc]

Very true Ir.
Easyrider if you are following this thread ,heres kinda sorta IMHO the way things work.
If you use innefficent speakers you will need lots of power.However low efficency drivers are kinda handicapped by slow response time.That is they dont really follow the incoming sine wave in a linear timely fashion.
Second point (if you are use to really crap low fi systems) if they are WAYYYYYY overrated in wattage output, in fact if you look around you will see some that the wattage output is actually greater than the incoming rated wattage?Maybe there is a small nuclear reactor in the amp?Most of the advertised watts ratings are just advertisng and have very little meaning in the real world.(Note! this applys to things that you buy at wallmart,circuit city, best buy ect ect,NOT to really higher end good amps)
I run +/- 12Vdc batt power on a LM3875T gainclone with Fostex fe-103e horns and i cant really turn the volume up to 50% as it just gets too loud,=>100Db.
I would suggest that you study up on efficent speakers and amps,then after you see what most of the ppl in these forums are about come on back and ask, then mabey we can help.
thanks
ron

 

[easyrider]

ron clarke thanks very much on the info.

so what your saying is if i use high quality parts and some decent speakers I can use like 1 LM3886 chip or LM3875 in you case and get decent sound?


now could anyone direct me to a easy to build amp. must be ac powered though.

must have a parts list too, thats all i ask.


thanks.

easy rider

 

[ronc]

http://www.decdun.fsnet.co.uk/gainclone.html

A good site for the newbies.I would not try the buffered GC right at first , unless you have a pretty good handle on electronics.
ron

 

[carlosfm]

However low efficency drivers are kinda handicapped by slow response time.That is they dont really follow the incoming sine wave in a linear timely fashion.
ron

Come on ron...
If you have a low efficiency speaker yes, they will sound slow and with a detached bass IF your amp is not man enough.
Give them a real amp and they will be fast.
There's no free lunch.
Generically speaking, less sensitive speakers have the disadvantage that they need power, but they have the advantage of being more linear.
Generically speaking again, a high sensitivity speaker shouts at you when playing at high volume levels.

 

[sam9]

ESP's project P3A sound.au.com is not out of the question for a first project, nor are the PM2 or PM22 from www.marchand.com.

This may sound dumb but I before you start be clear in your head which is more important:
A- a very, very sonicly excellent amp (low THD+n, good clipping charateristics, enough current to handle any forseen demands, etc) but in a cheap, ugly crappy enclosure.

or

B- a visually beautiful work of art that will catch the eye of your guests but which is of modest sound quality.

Of course you want both beauty and performance but trying for both in a first effort may get you neither. If you focus primarily on one goal you will be more likely to achieve that and with a little luck may not do too badly with the secondary goal as well.

I'm speaking from my own experience. This taught me that there is no such thing as "no compromise". But the compromise will work out better if narrow your focus initially.

 

[ronc]

Well carl thats true, but i have had better results with light cones and BIG magnets and generally lower Qts.Of course all i do is rear loaded horns.
I find the faster speakers to sound more realistic to a live performance, closer anyway.
I am however working on a design now using the ff85k which has a bit higher Qts (around .46 i think) and a seperate dipole sub rolled off at around 140Hz. The fostex will be run full range.
I had to come up with a smaller design as some of my customers wanted some thing smaller(than the horns) and less prominante (read too damn obvious) for their main rooms.
ron

 

[Jerry Parker]

possibly used to 'rubbish' brand name stuff (AIWA, Sony, Philips)?

thus isn't aware that even 15W is TOO loud for the average room (thru good speakers)

I agree, however IMO it depends on if you are listening to music or watching movies.

At reference levels, my subwoofer amplifier actually clips on Starwars Episode 2 when the spaceship lands at the beginning of the movie.

And my amplifier is rated at 1400w into 4ohms bridged (QSC RMX 1450)

Same with my speakers, I am definatly using more than 15w on peaks, and my speakers are pretty darn efficient, ~95dB 1w 1m.

However, with music, you are right, I usually use around .1 watt or so

However I occasionally put earplugs in and crank it up to 110dB+ levels with music

 

[ir]

i could get round to finishing the page on the 20W amp i built. the chip (LM1876) is electrically compatible (i.e pinouts EXACTLY the same) as the 40W stereo model so without ANY modification you can build either the 20W or 40W stereo amp with ease

here's the simple layout for building it on stripboard:

http://oc4free.scalded.net/amplifier/20+40WIC_veroboard_%20layout.gif

here's a pic of the power amp module once built:
http://oc4free.scalded.net/amplifier/20Wstereo_close_med.jpg

and the underside:
http://oc4free.scalded.net/amplifier/20Wstereo_bottom2_med.jpg

just say the words and i'll put up a complete page on how to do it

(here's the finished amp)