What makes a good amp good ?

Question is this :
Considering I choose some good design schematics. And lets also say, I choose the very best parts I can lay my hands on.
Is it OK to think that if I will make a PCB (by myself using the info from the schematic) and assemble everything together, I will get a "copy" (same quality or very close to the same quality) of the original amp ?

Do I even stand a chance at "copying" an amplifier at a good quality?

What about problems like ground loops ? schematics usually doesn't take care of that...

What happens when I design the PCB myself ?

Is etching your own PCB good enough ?

What other problems should I expect ?

What are the main considerations when I want to build the very best for myself ?
 
Or superior... I really want my LUXMAN 120a, so I studied the japanese board layout in great detail. They used phenolic , which is just highly compressed toilet paper with a bad habit of absorbing moisture.Pretty good layout.. with star grounding ..but they have the rail caps on board with the input stage using a common ground. :(

If you choose an amp to clone , pick one that uses high Ft/gain input stage and voltage stage devices. Then you can then be assured that you will find a modern equivalent and the compensation will work out fairly close. It does not hurt to simulate the original (with the original parts) ,to get a "feel" for the circuit. Read as many reviews as you can, the number of reviews and how positive they are are a good indication of the valor of the equipment.

I am amazed what the OEM's get away with.. BIG loops on the grounds , a million jumpers and small Pf caps to reign in the parasitics after the layout and production has started. WE , as the DIY'ers ,can add many extras , flyback diodes at the outputs , over rated capacitors and resistors , pretty led safety indicators , capacitance multipliers , AND make a better layout with separated grounds and split supplies for the different stages.

What is a fallacy is the cost. My 2 -250 watt power amps only came to about 70 dollars FOR THE PAIR , another $30 for the voltage amps and I will eat luxmans for breakfast at twice the power. This is far cheaper than reconditioned classic amps in this class, even on ebay. I did use the best panasonic and wima caps , Vishay 1% resistors, hardy ON semi output devices ... NO chinese fakes. Still, at $100 a pair , it can't be beat.

Where you REALLY spend the bucks is the power supply , my trafo(s) and the capacitors would of cost $200 if I did not salvage them. It is a long harrowing experience to design a good to exceptional amp , most of the expense is your time and learning curve. In the end , you can easily exceed the OEM's in both reduced cost and performance.(below-just priced it..)
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What about problems like ground loops ? schematics usually doesn't take care of that...

Too right they don't. And in my experience as a designer, grounding and layout are the primary determinant of how an amp sounds.

What happens when I design the PCB myself ?

Hopefully, you'll be aware of how important layout and grounding are to a good-sounding amp.

Is etching your own PCB good enough ?

Certainly can be. Have a look at wakibaki's exploits with a UV lightbox, he's produced some nice-looking boards himself.

What other problems should I expect ?

Expect your worst problems to be unexpected ones.:D

What are the main considerations when I want to build the very best for myself ?

Attention to detail. Patience. Rugged determination.
 

tryonziess

Member
2007-04-13 12:15 am
liquias.
At one time I shelled out some real hard earned money on a full high end stereo setup. I was extremely proud of this. To make a long story short I sold it all after hearing my DIY Leach amp.
The units you make with your own hands if done properly should and usually do surpass the high end commercial offerings.
First you will most likely match all of the components and test each item during assemble. You will have used an extra heavy gauge copper pcb. You will have chosen your components to be the best you could afford. You will have a power supply with more than enough grunt to handle the job EASILY.

In the end you should also have quite a bit of your money left over. You will also be proud of your efforts.

Tad
 
Topologie sounds.... current selection (decision during design) sounds

not overcompensating the amplifier sounds better... wide range sounds better too.

Also synergy.... something that sounds alike magic...and it really is.

When we think in current selection to each stage, of course we are thinking about parts that will work fine (linearity) with this voltage..so...part's selection matters too.

I am still searching the good answer for that.... 50 years researching and i cannot give you the answer...also cannot tell you the reason of our existence..if god exists or not...where he lives.... well.... what makes a good amplifier is a very difficult question.

regards,

Carlos
 
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Question is this :

Do I even stand a chance at "copying" an amplifier at a good quality?
Usually bought some pcb here will be better than you make
a clone cause some seller / group buy make from a big factory
& they knew what parts needed


What about problems like ground loops ? schematics usually doesn't take care of that...
If you clone all schema commercial amp usually handle this, if
diy amp if not the creator, the builder will be posted


What happens when I design the PCB myself ?
There were a lot of type of amplifier tube, transistor (Class A),
Transistor (Class AB) & Chip Amp. They had plus minus factor
so if you satisfy with an amplifier, stop dont build another


Is etching your own PCB good enough ?
it is depend what is etching you use (Price & quantity)

What other problems should I expect ?
- After you build and it not work at all, so you drop them in trash can
- when you try it is blow (remember electric can kill)


What are the main considerations when I want to build the very best for myself ?
- Hear a lot of amp by yourself, find out your taste
- Try to read a lot
- Try to learn from a lot of schematic first
- how big your budget ? if big enough build all the amp like master builder do
- destroyer x build more than 1000++ amp
- learn bout audio parts, by brand, by function, by community opinion
 
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What makes an amp good for you
is when it meets YOUR standards and needs.

For example, there are guys that have extremely high standards for how little THD an amplifier must have.
There are other that wouldnt settle for a low/medium Power amp. They can not accept less than 200 Watt.
There are others, that are not satisfied unless PCB and wiring is 100% perfect. Even by the looks of it.

So you define you goal. Set your standard.
You have some good questions in first post .. how to get there.
By your questions we already can figure out somewhat you want.
YOUR good amplifier.
 
Guys, thank you.
I am following up on your answers anxiously.

I must admit that my original question might have been perceived as a philosophical one, by some of you, while this was not my intention.
I meant for a practical question with practical design tips and hints. Things that are general enough, but still might not occur to a beginner designing his Amp Preamp and PCB out of schematics...
How to avoid (practically) given mistakes a beginner might do ?

pocoyo:
I would love to read about AndrewT's grounding endeavors, what thread are they on ? Where can i find it ?
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
Amplifiers of different topologies sound very different to each other...

As to wiring, this was quite a good thread, read it all.

http://www.diyaudio.com/forums/solid-state/101321-3-stage-lin-topology-nfb-tappings.html

Ultimately you have to understand the problems to avoid them in the first place, you can't just follow blind advice such as connect this here and that there... every design is unique in it's layouts and implementations.
I would recommend Doug Selfs books on power amp design as the best guide to explaining much of this... it's easy to read.
 
Guys, thank you.
I am following up on your answers anxiously.

I must admit that my original question might have been perceived as a philosophical one, by some of you, while this was not my intention.
I meant for a practical question with practical design tips and hints. Things that are general enough, but still might not occur to a beginner designing his Amp Preamp and PCB out of schematics...
How to avoid (practically) given mistakes a beginner might do ?

Where andrew is Mr. ground , I am Mr. practical.

1. start simple and with a lower power. A suggested amp is something like a DX original or my BX , or a blameless(I hold no bias). These amps have under 10 active devices and are VERY hard to screw up. Some truly qualify as audiophile and are used in VERY high class equipment. To build at the 40-50V rail level also keeps you safe in your first "steps".

2. I should of done this 2 years ago when I started this "adventure" , but modular is the way to go. You might find out down the road that you want to try something different ... it is a shame to waste good PCB's. Also with a modular system you can just unmount your input/voltage stage to alter compensations, upgrade components.. much easier.

3. Simple is best ,both in cost /reliability and the unlikely event of failure. being DIY , feel free to over-rate any and all parts (especially caps) and run your active devices as cool and well heatsinked as possible.

4. Have at least a oscilloscope (I didn't have one for a while- it was hard) , DMM and become proficient with a spice simulator (LT is nice).

These are the only general tips that can be given ,for each type of amp has it's own idiosyncrasies. Seeing an example is worth a thousand words (below).. that one took a month to get right , will build it next week , it is far more rewarding to design , prototype , and finally listen to YOUR creation than to just buy a kit.

I looked at all the diy amps here , all my hundreds of service manuals and read thousands of pages .. both subjective and technical, to come to my final design decisions. there is a lot of good advice to be had on this forum as well.

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Mr Ground!

I am going to argue the point.

I am still learning. I still get it wrong. I still find I cannot always solve a Hum and/or buzz problem. I can usually reduce it, but sometimes it just refuses to go to zero.
I have much more success with monoblock. I wish I could learn to be more consistently successful with two channel.

I did feel good when that new article popped up and so much agreed with what I had found and had been recommending.
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html

But, I am not an expert in any branch of Electronics nor Electricity. I am an amateur trained in building roads and gantries and fences and drains much of that Civil Engineering stuff.
 
I am going to argue the point.

I am still learning. I still get it wrong. I still find I cannot always solve a Hum and/or buzz problem. I can usually reduce it, but sometimes it just refuses to go to zero.
I have much more success with monoblock. I wish I could learn to be more consistently successful with two channel.

I did feel good when that new article popped up and so much agreed with what I had found and had been recommending.
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html

But, I am not an expert in any branch of Electronics nor Electricity. I am an amateur trained in building roads and gantries and fences and drains much of that Civil Engineering stuff.

That was meant in a light humor, Andrew. I am only a hard working street electrician myself. Dang, my house only has ground on 2 outlets (I had to add a bar and rod for these). :( They are for my PC's and amp ,BTW . :D
Your input is most often quite correct and concise , so it is greatly appreciated. :)


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