big plan: to build a professional amplifier

[zappee13]

Hello,

My name is Arnold and I live in Hungary. I have a big plan: I want to make a complete professional amplifier with preamp, power amp, input selector, volume control and vu meter. The hardest part of my plan: I have to pack these parts in two boxes : In the first box will be the power amplifier and speaker protection circuit. In the second box will be the other things.

I spent lot of time to search on internet and forums and I found lots of circuit diagrams. I selected some of them.

power amplifiers:

• ST151 100W amplifier or ST151 100W amplifier [hu]
• MOSFET 200W

preamplifiers:

• Simple High Quality Preamp For Hi-Fi
• Minimalist Discrete Hi-Fi Preamp
• High Quality Audio Preamp (Mk II)
• Hi-Fi Preamplifier
• Hi-Fi Preamplifier
• Module Line amplifiers
• Symmetrical Class A Preamplifier [1]
• Symmetrical Preamplifier Class A [2]
• Symmetrical Audio Class A preamplifier [3]

volume controls:

• Audio Volume Relay Attenuator with IR Control
• Audio Switch
• Automatic Loudness Control
• Stereo Preamplifier with Bass-boost

vu meters:

• VU Meter with UAA180
• VU Meter 2
• 0... -40 dB VU meter by Archy

At first I want to make a professional power amplifier (~70-100W) and preamplifier with tone control (bass and treble).

Could you tell me what do you think about my power amplifier and preamplifier circuits? What do you suppose me? Which amp and preamplifier to build? Or could you suppose me a better power amplifier and preamplifier circuits?

Thank you, Arnold

[sakis]

neither the first nor the second can be called ""professional" amplifiers home use amplifiers may be .... but professional is simply out of the question ....


professional amps are to be used in heavy duty like PA . live music stage monitors club bars or theaters .... none of the above will be able to do that ( power is way too low )

then again between these amps and a professional amp the issue is not only power since this is quiet easy to achive ...the bigest diference is the protection methods against any possible abuse ( overdrive , high power demands , temprature , arround the clock full power and so on and on )

Finally most of these circuits will work ....and you may make any choise between them ... but matching circuit A with circuit B regarding gain/supply / wiring will make all the diference in you machine ....


I f you are looking for a high quality equipment all small details are very importand like wiring ,ground loops, power distribution , these small details can badly effect an otherwise very good circuit


regards sakis

[Gordy]

Originally Posted by sakis

neither the first nor the second can be called ""professional" amplifiers home use amplifiers may be .... but professional is simply out of the question ....

Hi sakis. I that you may have mis-interpreted Arnold. When he says 'professional' I think he means 'high quality, as you can buy in the shops', and not necessarily 'public address' or that type.

[sakis]

OK ....no probs i hope that he gets the point ( s) though for both

[Gordy]

Originally Posted by zappee13

I have a big plan

Yes you do!

I suggest that you start simple, get it working reliably, and then add things to it.

To this end I would look towards a simple preamplifer and power amplifer from ESP (sound.westhost.com). Use basic protection circuits but do not include tone controls and VU meters to start. These things can be added when you have the basic circuits functioning OK.

So how much power do you need? That depends on the efficiency of the loudspeakers, how close you sit and how loud you like your music. Maybe 100W is enough, or maybe 20W is enough, or maybe just 5W?

The volume control at
http://www.vaneijndhoven.net/jos/switchr/design.html
seems fine, but also look at
http://electronics.dantimax.dk/Kits/...ors/index.html

For a decent box consider http://www.hifi2000.it/default.asp?Langid=1

Good luck
: )

[derwhalfisch]

like this sort of thing?

http://www.sound.westhost.com/phpBB2...hp?f=13&t=2013

the circuits he's used are all detailed in the next link;

http://sound.westhost.com/projects.htm


Not that i'm reccomending Eliot's designs as i havent built any, just that this is a lovely example of a complete unit with some protections thrown in, la de da, and i thought it might be of some use to you Looking at the circuits this guy has used though, and the cost of chassis and so on, I reckon he's spent as much doing this DIY as you could spend second hand to get a commercial unit. Of course then you havent built it yourself ;P Best of luck my friend

[AndrewT]

MOSFET200W uses resistor biasing without any temperature compensation.
This demands the use of Lateral FETs for the output stage.
You will need 4matched pairs for each channel.
To give you any chance of matching your 4pairs you will need to buy at least 20devices to get your selected 16devices. This alone will cost a fortune.

[zappee13]

yes, yes. I am sorry
when i say "professional" it means a high quality amplifier for home use.

[sakis]

then start with something really simple to gain expirience

do an amplifier ..... stand alone ...no tones or anything like that .....avoide non tested circuits

[zappee13]

I don't want to buy a commercial amplifier I want to build it myself

In the past I made lots of electrical units. My favorite areas were amplifier and light units with triac. My last amplifier what I prepared were Quad 405 for 6 years ago. Now I have been working at a big company as java architect for 8 years.

Well, I need 70-100W power amplifier.

I drop from my list the last circuit (MOSFET200W) because its output power is high (200w) for my. But I found another power amplifier : quasar and ESP Hi-Fi Power Amplifier.

I agree with sakis: small details are very important, but if I select a bad construction, then sure, that the final result will not be good

Now I have three power amp circuit diagrams: ST151, quasar and ESP. I know I have to make a choice one of them but it is not too easy for me because I do not have practice in this. In the past I just made lots of stupid electrical units for me and my friends without quality