Guidance for a 'beginner'

[fooboo]

Hi All

This is my first post For the past year I have been working on a project. A small part of this was the amplifier. In this case it was a TDA2003 which preforms perfectly for the design it is a part of. I am now working on a bridged version, well more like thats finished , Which has proved more of a challenge. One circuit design I used off the net didn't work but I got there in the end and have 8W at the disposal for the original circuit. So as I went through all this I found this site and a lot of stuff going on based on the 'gainclone' amplifiers. Right I am getting to the point now . I am a builder of electronics not a designer and there is much I don't understand and probably never will. I just like soldering things up and trouble shooting if they don't work, thankfully, so far so good! But I have always fancied making my own audio amp (for music) and speakers. I am now in a position where I can, albeit slowly, achieve this teenage dream (I'm now 40 ) So I've looked around at all the clever stuff you chaps have done and I would like to build something. Can you point me in the direction I need? I can etch my own PCB's so something with a freely available pattern would be good.
I am looking to go stereo (2 mono circuits) and build the PSU for it. Power Output? well I guess this will be governed by the spec of speaker cones I get. So a bit of guidance would be good especially as I would like to make my own enclosures. I guess 'simplicity, quality of sound, not super expensive' is the governing directive. I will be using MP3 players, CD, and turntable as the primary inputs.......the latter will need an RIAA pre amp. I know that bit because I built one from a velleman kit way back in the 80's when I was in digs so I could listen to my vinyl collection I know there is a huge dearth of options and ways of doing this which has got my interest but I have no Idea what to choose from all the available info. So I will rely on your experience if I may.

regards

Fooboo

[Nuuk]

Fooboo, welcome to the wonderful world of chip-amping. As you can see, you can find just about all the help that you need right here on this forum.

But may I humbly suggest that you start off with some homework by visiting the Gainclone pages at Decibel Dungeon.

To make things as easy on yourself as possible, aim to build a power amp, and a separate pre amp with the necessary inputs and RIAA stage etc. You will find that infinitely less confusing that trying to put it all in one box IMHO.

If you are yet to choose speakers, do yourself another huge favour and get something as efficient as possible. Your chip amp will love you for that and reward you with even better sounds.

I nearly forgot. Start off with a basic chip amp. Don't worry about all the different versions, different power supplies etc. If you start with a basic as a reference, you will be able to change things later and hear what you actually doing.

[fooboo]

Thanks Nuuk

Currently spending lots of time over at DD I was thinking along the lines of separate Pre amps, power amps and PSU! Speaker wise I am remembering a pair of Mission 761i's I heard a long time ago. ARcam CD and Amp feeding them........Actually it was like there were no speakers and the band were present! Right back to DD for more education!

regards

Fooboo

[john blackburn]

fooboo

Don't let him seduce you with his smooth typing ways, turn back now while you have chance. You are entering addiction country.

I was once like you, a casual Decibel Dungeon visitor. Since then, I'm now on with my fourth chipamp, with most of the bits laid by for a fifth. I only have eight rooms in my house but if I build an extension I could have one in there as well..........

Keep us posted with your progress.

John

[Nuuk]

Only four John! Tut tut!

Well keep that iron hot, the chip amp scene is about to get a huge kick up the rear!

Fooboo, get stuck in there, you can already see the sort of riff-raff that I am keeping off the streets.

[fooboo]

It's to laaaaaaaaaate!!!!!!!!!!!!!!!!! I can't turn back! His writing is so eloquent
Seriously though it's all interesting reading. I'm currently at the stage of 'I've read
far to much and it's hurting'. Now P2P or PCB, it's all so much fun! Right then back
to DD for a fix!

regards

Fooboo

[john blackburn]

Hi Nuuk.

I will wait in eager anticipation for bottom kicking developments, hot iron in hand! I assume there will be an announcement when you have it sorted.

What are you up to? I had thought that all permutations of the chipamp were covered but maybe I'm wrong on that as well. As the bloke I was apprenticed to was fond of saying "It's not often you're right but you're wrong again" He was the one drinking tea that had been stirred in a most unconventional manner mindst.

As for the Riff Raff coment I prefer to think of it as "Earthy Rustic Charm" with a hint of beasts of the field about it.

John

[fooboo]

Hi Gentlemen

Well I have looked at sourcing the primary Items, Toroidal transformers 2 off and a pair of LM3785's. both from Farnell. Luckily that takes me over the minimum order limit . I can also get a pair of LM3886's from Cricklewood electronics. After that it's just sourcing the discrete's, I have an account with Rapid online . I am getting both chip types because I am unsure which to attempt first but all being well both will get built . I am a bit nervous of the P2P setup but I think it's bloody clever. I have found a couple of PCB patterns that I could print of as well but on the whole DD is soothing my tattered nerves . I think the nerves stem from having built most of my circuits on vero board and a year ago I made my first home made PCB successfully first time so I am a bit tied by habit to fitting things to a PCB of one sort or another. I have done a bit of 'cludging' (I think that's the term) when I needed to fix a design problem. A case in point being the bridged TDA2003 amplifier I have just finished. It failed on first trials but I added 2 poly caps and an electrolytic radial, on the track side, very neatly with a few deft bends of the wires. After that it worked and I redid the PCB with provision for these bits to be fitted topside on the final design. Is there a PCB pattern for either of the GC's on the DD site? I know I could design my own but although I understand that I/O's and power planes need good separation I really suck at self designing PCB's. I can adapt and modify existing patterns but thats usually just to suit components that may be larger or smaller than the original design. My current PCB for an existing circuit has shrunk by 10mm on the length and width as I have fiddled with parts orientation resistor wire lengths. basically the PCB traces are unchanged just a little more compact. That's my limit Still I'll stop waffling now and go read some more.

Just been through the Rapid site 'by hand' and I can get the LM3876.....any good?
and the toroidal coils

regards

Fooboo

[john blackburn]

fooboo

Make sure you know if you have the T or TF chips. I ordered LM3875Ts (uninsulated) and then found out the price of silpads, it cost twice as much for the insulating pads than the cost of the chips.

Using a pcb and known good design makes perfect sense for a first build, theres great happiness value in it working first time. You can get exotic with the next one and start comparing how one type compares to another until you find the sound for you.

Have you seen this site? http://www.madaboutsound.com/

He (Vikash) has PCBs for the LM3886 in stock, and a good range of speaker drivers, heatsinks, connectors etc to boot. Add to that he's a moderator on here, a good bloke to do business with and you are onto a winner in my opinion.

John

[fooboo]

Oh yes been there! very nice they are to and already added to my bookmarks!
I think I may go with the PCB first then Go on to a DD GC. Half the fun is going to be making a nice enclosure for the unit(s). Two other items that I will need to address are.......My 'HiFi' is still in it's box since I moved 2 years ago as there is nowhere for it to go as yet. On top of that it's a modular Akai with a rubbish turntable and it can't be split to use the 3cd changer on it's own as it has a proprietary connection system. Apart from that it would probably not do justice to the Amplifier I intend to build. So without having to sell an arm and a leg what would be a good introductory CD player, Tuner, turntable, and possibly tape player in that order. Also I doubt the speakers that came with it are good enough either so I want to build my own pair. What is a good beginners design to self build and what would be a reasonably priced pair of drivers to use as the basis for picking the cabinet design. I fancy floor standing, small footprint, and 4-5' tall ? I know it's a lot of questions and I have read bucket loads on here and at DD but I still lack a clear direction I fear.

These look very nice, good price and full range to boot. 2 x CSS FR125SR & Firm Hold Fasteners

regards

Fooboo (who asks to many questions)