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Old 31st August 2010, 12:30 AM   #1
liquias is offline liquias  Israel
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Default 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 ?
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Old 31st August 2010, 02:10 AM   #2
tinitus is offline tinitus  Europe
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What makes a good amp good ?

I would say good speakers
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Old 31st August 2010, 02:13 AM   #3
adason is offline adason  United States
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do not forget good signal source
(amps are **** in **** out devices)



oh ****, I can't say ****
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Old 31st August 2010, 03:00 AM   #4
SY is offline SY  United States
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Quote:
Originally Posted by liquias View Post
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 ?
Only if your PCB design and layout skills are the equal of the original designer.
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Old 31st August 2010, 03:58 AM   #5
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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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Old 31st August 2010, 05:17 AM   #6
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Quote:
Originally Posted by liquias View Post
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.

Quote:
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.

Quote:
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.

Quote:
What other problems should I expect ?
Expect your worst problems to be unexpected ones.

Quote:
What are the main considerations when I want to build the very best for myself ?
Attention to detail. Patience. Rugged determination.
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Old 2nd September 2010, 09:05 PM   #7
liquias is offline liquias  Israel
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Default Guys, thank you

for the info.
I am now wondering (although maybe in the wrong forum) about the same question regarding a passive/active Preamp.
What will be the main concerns ? what should I avoid ?
What problems am I likely to encounter ?
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Old 2nd September 2010, 09:43 PM   #8
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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
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Old 2nd September 2010, 11:30 PM   #9
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Default 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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Last edited by destroyer X; 2nd September 2010 at 11:32 PM.
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Old 3rd September 2010, 01:12 AM   #10
Pocoyo is offline Pocoyo  Indonesia
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Quote:
Originally Posted by liquias View Post
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

Last edited by Pocoyo; 3rd September 2010 at 01:16 AM.
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