diyAudio (
-   Solid State (
-   -   looking for schematics 4x80Wrms (

belg 13th September 2003 03:50 PM

looking for schematics 4x80Wrms
My classmates and I al had to pick a project to build and depending on what it is and if it works and if it's hard to make we get grades that are essential for me to complete my last year.

I didn't have an idea what to build so i went to talk with my dad.
It didn't take him long to tell me what he wanted:
transistor amplifier 4x80W rms, in and out for tape, in for Cd, SCART in for TV, pre-amp for mic and pickup. Goodman speakers or Cerwen vega. when I heard him busy my head kindoff exploded 'cause I don't yet have the knowledge of audio like he made me believe he has. what i get from it know is that he wants 4 speakers, each speaker has a 80Wrms amp, per 2 80W amps there is a normal amp, there al in signals come toghether and the out's of the 2 pre-amps to. the big problem is finding schematics like the one's i need and the need to know if the schematics are good.

so if someone has a schematic for a +/-80Wrms amplifier, a power supply to go whit that and pre-amps for mic and pick up it would be a great help

also site's with more info on the subject that you think that would realy help me out then please post them.


keyne 13th September 2003 06:46 PM

hello belg,
no offense intended, i just want to save you some frustration.
there is no way you can make this work... mic preamps and phono preamps are hard to build because they amplify tiny signal levels, they are very sensitive to hum and noise pickup. this stuff is a bit hard to get right.
All the signal switching you listed can be worked out...

making a four channel power amplifier is a big enough school project!
look at Rod Elliot's site for some schematics. he also sells boards.
what about
for an easy poweramp.

there is very little chance of success without considerable experience for the project you outlined. And a non-working project will probably not net you good grades, eh? So may i propose a four-channel poweramp for now and a matching preamp (ideally kit based) for later?

belg 14th September 2003 09:51 AM

okay, so making my own pre-amp is out

that's not to big of a problem 'cause that was just an option. We won't be using a mic or pickup anyway. I just wanted to make a full system.

My knowledge about electronics is enough to build something with just the schematic, I've got the possibility to use ultiMate programs to draw te PCB and also to make PCB's is not a problem.

Another problem is that the sustem really has to be good, my father is really a music fanatic and first he wanted amps like MBLE made them altough they're broke for over 20 years but now philips sells those amps, he wanted goodman or cerwen vega speakers so i'm looking for a verry good amp.

What I saw on that site would be nice but I'm not shure if it is what i'm looking for. If you know more examples of good amps with 100Wrms or something like it that would also be great

thanks keyne

belg 14th September 2003 10:07 AM

'cause i'm still under moderation i'll reply here and paste this post i'm my post above and delete this one, srry for this

I was checking out the site that keyne gave me and browsed the other projects and i found this project:

I found it more interesting 'cause the overall quallity would be better and the output is more like i wanted it.

What do you think?

belg 14th September 2003 05:18 PM

ok here I am again, i alsow saw that posts are unediteble, ok so I learn something new

i've found some stuff that was reallyyy interesting to me
i'll be making this amp:
so I order 2 PCB's and use it with 4ohm and tadaa 100Wrms
as pre amp i'll be making this one:
it has the desired controlls and also I can order the PCB
schematics on that page where also verry helpfull and they made me understand the whole idea of it
as phonoamp i'll be making this
again I order the PCB and my work is complete

with this my father wanted to use goodman or cerwen vega speakers, i'll wee what's availeble today

the stuff i just typed, does it look okey to you guys, I don't know yet what works good togheter and what won't

is someone willing to check it out for me?

thx guys

keyne 15th September 2003 07:51 AM


the ESP projects with their associated PCBs look to be the right thing for the project. This is not tweaky high-end stuff, but this also means you have a very good chance of making things work with his PCBs.
It would be an advantage if you had an oscilloscope and a signal generator so you can verify performance of the finished product.

build it carefully and slowly, and modular! check all pieces before you connect them together.

Goodmans is out of business i think. Cerwin Vega (spelling!) is here: . I don't think these speakers are my cup of tea so i will refrain from commenting further on this matter.
Regards and Good Luck with your project!

belg 15th September 2003 03:33 PM

hey keyne, i have an oscilloscope and low frequency generator that can go up to about 2Mhz, i think there are some more things i have acces to at school, that won't be a problem.

If the teacher accepts and i hope he does 'cause i love this project then i'll start ordering the pcb's and the parts.

The cooling fins, do they have to be outside of the casing or dan it be inside with enough vent holes?

thx for the cerwIn vega :nod: site, i'll be surfing that one for a while to. You also say that cerwin vega isn't your favorite but then what would you recommend, i myself don't have a clue what to use but my father said he wanted these, what are the pro's and contra's?

thx for the help keyne

belg 15th September 2003 04:35 PM

okey i've switched preamp, i'll be building with power supply

keyne 16th September 2003 08:44 AM

the cooling fins should be outside, they CAN be inside (as in all the commercial mid-fi equipment) but you really have to make big vent holes in the top and bottom of the enclosure. Or you need a fan, which obviously is noisy (but you could add temp control for the fan to your project, too...).

I don't buy speakers, so i have no recommendation, sorry! i build my own... all i can say that it doesn't make much sense to select a speaker based on brand name alone, because the range of speakers offered by one company is vast. I guess your father wants a certain sound associated with a CV speaker he already heard and not just the sticker on the box, eh? Maybe he can help you selecting the speaker based on catalogs or the website or - much better - actually listening in a store.


belg 16th September 2003 03:26 PM

well he has always been a fan of audio and listening to music, i think it's like you say, that certain sound one produces i guess.

surely we'll be going to a store to listen and so on butt if someone has a good idea to fit this amp, please tell me.

about that fan, indeed i could try to do that whit a NTC resistor, that might work, butt my dad says that if it's a good amp and there are vent hole's at the back, bottom, side and top (at the end of the casing were the fins will be placed) then the heat won't be that big, but also the supply's will be placed in that same casing so maybe...

i'll try to convince him to putt te fins on the outside or to put a fan with an ntc around it

All times are GMT. The time now is 05:59 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 18.75%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio