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Old 28th January 2004, 10:29 PM   #1
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Default Gainclone basics for an enthusiast who's new to them

Hello...
I'm a non-EE trying to learn about gainclones.

I've done some research around here, but haven't really found any threads with many discussions of fundamentals - primarily, lots of specific application and build discussions.

So, I thought I'd start one.

I've got a few questions that I'd be highly grateful to receive answers on.
And I'm sure I will, this forum has amazing members, honestly.

__________________________________________________ _

In my poking around here, I've seen some discussions that seem to put gainclone amplifiers on par with big dollar high-end home amplifiers.
How does the sound quality compare?
What design/construction factors affect it?


If the sound quality truly is superior - or even comparable - given the low cost of the componentry (save for the expensive transformer), then...
Why don't we see more commercial high-end chip amps?

__________________________________________________ _

I have several questions related to the comparison of gainclones to standard class A/B and class D amplifiers, and what applications one might substitute a gainclone, and what practical limitations exist with them.
Are gainclones class A/B amplifiers?
What is their efficiency, as a general percentage?

I've seen mention of class B even... and wasn't aware it was even used in audio... in fact, I had believed there was a forum of current switching noise inherent in it.

How much power can they be built for?
How much output power can I build a gainclone to produce?
How can I manipulate this in my design, if it's a design variable?


What impedance goals can be catered to?
Down to what sort of impedances can I build a gainclone to be stable down to?
How can I manipulate this in my design, if it's a design variable?


__________________________________________________ _

I've seen many people using gainclones as full-range amplifiers.
Is the gainclone best suited for full-range duty?
Can it be built for subwoofer duty (ie. higher output power requirement applications)?


__________________________________________________ _

I read a review regarding a commercially-available amplifier that Peter Daniels designed, that included a special foot that could be equipped with a pad to change the "voice" of the amplifier...
Searching for more info led to some threads talking about gainclones being sensitive to vibrations.
How do (the explanation of the electrical/mechanics involved please) vibrations to the chassis affect the sound qualty / "voice" of the gainclone amplifier?

Is this one of these non-scientific things that certain people "swear" makes a difference, or is this a real anomoly?
Is it explainable?

__________________________________________________ _

As I understand it, the cost of the componentry is almost trivial, nominal... the exception being the transformer, for the power supply.
I've seen different chips being discussed.
What is the cost of the componentry?
Where can I best obtain the transformers and chips?

What are the differences between chips?
Why would I select one over another?


__________________________________________________ _

I've seen people discussing using DC batteries rather than obtaining the expensive transformer.
I'm also seriously involved in high end car audio, sound quality applications. The voltage supply by nature is DC, making this seem even more practical for car audio applications.
However, the question earlier regarding gainclones and vibrations to their chassis certainly could come into play, if that is truly a factor.
Could a gainclone be built to run off of a 12 volt DC supply?
Would this impart any limitations on the level of output power that could be produced by the gainclone?


__________________________________________________ _

I realize there are a pretty significant number of questions here, spread across a few general areas, but all tied to fundamentals, I think.
I'd love to start a gainclone project by springtime... and realistically, I can envision both home and car projects.
I'm already starting my research - I appreciate any help that can be given!
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Old 28th January 2004, 11:29 PM   #2
Ropie is offline Ropie  United Kingdom
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Could you be a bit more specific, please?

Yes, the gainclone is a very good amplifier (I'm not sure of any measurements) and you can probably build one cheaply and easily enough so it's not too much of a problem if you don't like it (unlikely).

Pick a schematic you think you can handle - they are everywhere on the net - and hardwire it together if you have enough experience; pcbs are apparently more hassle than they're worth. If you need help there are plenty of people who can help you with component choice, grounding (v important in GCs), etc, on the way.

Regarding battery power, speak to Roncla, usually found on Amp Chip DIY.com
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Old 29th January 2004, 12:20 AM   #3
matjans is offline matjans  Netherlands
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Default Re: Gainclone basics for an enthusiast who's new to them

my .02$ worth (where's the euro sign?!)

Quote:
Originally posted by geolemon
How does the sound quality compare?
What design/construction factors affect it?
sound quality is surprizingly good. Depending on build quality it out-plays many amps. Quite some Bang for few bucks!
WHat does not affect the sound of this amp... you tell me.

Quote:
If the sound quality truly is superior - or even comparable - given the low cost of the componentry (save for the expensive transformer), then...
[COLOR=darkred]Why don't we see more commercial high-end chip amps?
Dunno, there's not much to brag about. Maybe that's it. The only thing one can really say is that the GC philosophy (less is more) works...

Quote:
Are gainclones class A/B amplifiers?
What is their efficiency, as a general percentage?
yes, they are a/b amplifiers. My guess would be they're about 40-50% efficient.

Quote:
How much power can they be built for?
How much output power can I build a gainclone to produce?
How can I manipulate this in my design, if it's a design variable?
There are a few designs out there for say 200W (audio power) amps. More than enough one'd say. You can do this by bridging or parallelling chips.

Quote:
What impedance goals can be catered to?
Down to what sort of impedances can I build a gainclone to be stable down to?
How can I manipulate this in my design, if it's a design variable?
I wouldn't really use speaker sets with impedance below 4ohm.

Quote:
Is the gainclone best suited for full-range duty?
Can it be built for subwoofer duty (ie. higher output power requirement applications)?
yes, very well. for subs you could add more capacitance.

Quote:
How do (the explanation of the electrical/mechanics involved please) vibrations to the chassis affect the sound qualty / "voice" of the gainclone amplifier?
Is this one of these non-scientific things that certain people "swear" makes a difference, or is this a real anomoly?
[COLOR=darkred]Is it explainable?
No clue. I have experienced this, though. Putting nice feet under your amps makes it sound clearer, nicer, tighter bass. I seem to remember a thread about this somewhere around here but searching didn't help.

Quote:
What is the cost of the componentry?
Where can I best obtain the transformers and chips?
What are the differences between chips?
Why would I select one over another?
Cost depends on how much you invest in it. You can build one from scrap or you can go exotic (thus expensive).
Selection of chips methinks depends largely on availability in your country. And again, cost. lm3875 is cheap, tda548/9 is more expensive.


A pretty lengthy post, all in all.
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Old 29th January 2004, 12:24 AM   #4
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This reply took a while:

>How does the sound quality compare?
Some equal it to $1000.00 to $2000.00 amps.
>What design/construction factors affect it?
many, depending on who you believe.

>Why don't we see more commercial high-end chip amps?
I do not have the finances to pay $2000.00 for an amp with a $5.00 chip in it.
I think if I had a lot of money for an amp, I would go for a "classic" design, not GC.
__________________________________________________
for this section goto:
http://www.egr.msu.edu/classes/ece48..._datasheet.pdf
This is a good article.
also, goto:
www.national.com and search for application note "AN-1192".

>Are gainclones class A/B amplifiers?
Yes.
>What is their efficiency, as a general percentage?
much better than a class "A" amp.
>How much power can they be built for?
An-1192 =--> 200 watts.

>How can I manipulate this in my design, if it's a design variable?
Generally limited by power supply voltage and heat sink size in high power amps.
>What impedance goals can be catered to?
hard to drive less than 4 ohms.
>How can I manipulate this in my design, if it's a design variable?
hard.
__________________________________________________ _


>Is the gainclone best suited for full-range duty?
subs, mids, tweets, and FR.(may depend on speaker effenchency.
>Can it be built for subwoofer duty (ie. higher output power requirement applications)?
I built a "bridged" amp (2 ea. LM3886) in 1997 for a computer subwoofer using a 6.5" speaker ($10.00) - it rattled walls in a 20x35x14 foot room.
__________________________________________________ _

>Is this one of these non-scientific things that certain people "swear" makes a difference,
yes.
>Is it explainable?
IMO - no, YMMV.
__________________________________________________ _


>What is the cost of the componentry?
Chip $5.00, resistors $50.00, Capacitors $50.00, connectors $35.00 ea, Case $big-bucks.
>Where can I best obtain the transformers and chips?
I will sell you a sonicly perfect transformer for $2000.00, on the other hand you could buy a plitrin for $65.00 (www.piltron.com) which most say works fine.
>What are the differences between chips?
5 chips = 56 opinions. Most are using either LM3875 or LM3886
>Why would I select one over another?
Power output, so and so says chip xyz is sonic superior to chip abc.
__________________________________________________ _

>I've seen people discussing using DC batteries rather than obtaining the expensive
Using auto batterys is VERY dangerious, not for novice, I would never use them, not worth the risk. I would consider sealed Lead acid or Gel-cell.
>Could a gainclone be built to run off of a 12 volt DC supply?
>Would this impart any limitations on the level of output power that could be produced by the gainclone?
Yes, Read Lm3875 datasheet - page 9 "output power vs Supply Voltage" = maybe 5 watts.
__________________________________________________ _

I realize there are a pretty significant number of questions here
(I had to break for dinner, sharaz may effect many answers.)
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Old 29th January 2004, 01:19 AM   #5
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Thanks for the replies so far!
Quote:
Originally posted by Ropie
Could you be a bit more specific, please?

Yes, the gainclone is a very good amplifier (I'm not sure of any measurements) and you can probably build one cheaply and easily enough so it's not too much of a problem if you don't like it (unlikely).

Pick a schematic you think you can handle - they are everywhere on the net - and hardwire it together if you have enough experience; pcbs are apparently more hassle than they're worth. If you need help there are plenty of people who can help you with component choice, grounding (v important in GCs), etc, on the way.

Regarding battery power, speak to Roncla, usually found on Amp Chip DIY.com
Just so that I'm clear, I'm looking to learn this unique architecture, which is "new-to-most".

I can't be more specific, because as I mentioned in my first post - there's lotsof information on this forum with respect to particular applications, schematics, chips, etc...
...but seemingly quite little on fundamentals, concepts, considerations...
The things that would lead you to choose one of those schematics, and the things that would lead you to select particular components and values, amounts of capacitance, etc...
That seemingly missing (and I'm hoping I'm mistaken!) information is what I seek.

It's absolutely not my style to "just pick one" and run with it.
My concern is obtaining the knowledge to let me select superior results... a means of planning, to get there.
Maybe I'll build several, I'll probably have to.

It is true that I need something SQ-oriented, for home...
I currently have a QSC MX1450 here that I obtained more or less for stress-testing loudspeakers (I do R&D as a loudspeaker designer for a car audio manufacturer), but really haven't got anything with real finesse for my home system...

...it is killing me particularly upon my return back from CES 2004, where I spent a significant amount of time at Alexia Park, listening to systems where the two monoblock tube amps together cost more money than my house...

So, I'm sure I won't be disappointed, for the home.

But I'm more of an experimenter... I don't just want to build, and enjoy, that's not my goal.

I want to explore, to learn, to understand these amps.
Get my feet wet (er... figuratively. ).

I'd much rather learn the concepts, the pros and cons, the ins and outs of these amps, and never end up with one of my own...
...than not learn the concepts, but end up with a pair of nice sounding amps.

It's not about obtaining a nice amp, it's about obtaining knowledge.

That's just fundamentally me.
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Old 29th January 2004, 01:31 AM   #6
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Quote:
Originally posted by geolemon


It's not about obtaining a nice amp, it's about obtaining knowledge.

That's just fundamentally me.
That is quite simple. Use search function, type "gainclone" and read all the posts. Then build few amps and tell us what you think.
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Old 29th January 2004, 01:34 AM   #7
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Default Re: Re: Gainclone basics for an enthusiast who's new to them

Quote:
Originally posted by matjans
my .02$ worth (where's the euro sign?!)
It's worth a lot more than that - thanks!
Quote:
Originally posted by matjans
There are a few designs out there for say 200W (audio power) amps. More than enough one'd say. You can do this by bridging or parallelling chips.
OK, fair enough...

200 watts is definitely more than enough...

Do you know what upper-limit there is for a single chip based amp? 100 watts then?

Quote:
Originally posted by matjans
I wouldn't really use speaker sets with impedance below 4ohm.
Is this a fundamental limitation (ie. a function of what's built into the chips), or is this something that can be manipulated... limited essentially by how much current is flowing (ie. more current flows, given the same amount of power, at lower impedances)?

Quote:
Originally posted by matjans
Cost depends on how much you invest in it. You can build one from scrap or you can go exotic (thus expensive).
Hmm...
I'll go reasonably exotic as needed, on functional componentry... or even a massive base to damp the whole thing physically...
...but I say that in part because it seems like we're talking about the difference between $2 capacitors and $10 capacitors... still "budget-worthy".
It's an amp for experimenting... someday, after I'm done playing, maybe I'll create one with an "exotic" look, hardwood & acrylic case, etc.
But, well, that's not what I'm shooting for right now.

Quote:
Originally posted by matjans
Selection of chips methinks depends largely on availability in your country. And again, cost. lm3875 is cheap, tda548/9 is more expensive.
Well, in the good 'ol USA here, I'll have to hope I can get my hands on virtually 'whatever'.

I do have one of my distributors in Korea, if that were somehow advantageous (heck, most solid-state transistor amplifiers are born, at least to some degree, in Korea ).
Worst case, I'm sure I could talk him into mailing me a chip... sounds a bit extreme though.

Quote:
Originally posted by matjans
A pretty lengthy post, all in all.
Yeah... I probably should have posted my original questions before bothering searching...
...that just led me to having more questions!

Thanks again, for taking the time to reply.. it's very much appreciated.
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Old 29th January 2004, 01:47 AM   #8
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Quote:
Originally posted by Peter Daniel


That is quite simple. Use search function, type "gainclone" and read all the posts. Then build few amps and tell us what you think.
Ah, if only it were!
I've been doing that for three days - and doing nothing but creating more questions.

As I mentioned (twice now):
Lots of posts on particular builds, specific applications, "I finished my...", etc. all applied...
But very little, on basics, fundamentals, theory, or planning.

Try searching for
"gainclone basics"
"gainclone fundamental"
"gainclone fundamentals"
"gainclone theory"
"gainclone design"
"gainclone overview"
etc.

I've been at it for days... about three now.
It's time to start learning.

I took nuuk's personal recommendation to search for some of your threads in particular, and while I can appreciate them (beautiful work), I just didn't find fundamentals.

Possibly, I'm misunderstanding things, from this "fundamentals" level:
I believe there are several schematics... I have seen four, so far... no doubt there are more.
I believe there are several chips... I've seen at least five mentioned (by model number), I believe there are more.
I believe there are several components and values - within the scope of a particular schematic (such as capacitance) that are essentially variables.

I believe there are reasons that I would choose one particular schematic over another...
I believe there are reasons I would select one particular chip over another...
I believe there are reasons I would select particular components and values...

Am I mistaken?

"just build an amp, and tell us what you think"
is like saying
"just buy a car... and decide later if that's the right body style, engine, suspension, tires, etc. for your driving needs."
(to draw an analogy)

See what I'm looking for?
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Old 29th January 2004, 01:53 AM   #9
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Quote:
Originally posted by geolemon


Ah, if only it were!
I've been doing that for three days - and doing nothing but creating more questions.

As I mentioned (twice now):
Lots of posts on particular builds, specific applications, "I finished my...", etc. all applied...
But very little, on basics, fundamentals, theory, or planning.

Try searching for
"gainclone basics"
"gainclone fundamental"
"gainclone fundamentals"
"gainclone theory"
"gainclone design"
"gainclone overview"
etc.

I've been at it for days... about three now.
It's time to start learning.

I took nuuk's personal recommendation to search for some of your threads in particular, and while I can appreciate them (beautiful work), I just didn't find fundamentals.

Possibly, I'm misunderstanding things, from this "fundamentals" level:
I believe there are several schematics... I have seen four, so far... no doubt there are more.
I believe there are several chips... I've seen at least five mentioned (by model number), I believe there are more.
I believe there are several components and values - within the scope of a particular schematic (such as capacitance) that are essentially variables.

I believe there are reasons that I would choose one particular schematic over another...
I believe there are reasons I would select one particular chip over another...
I believe there are reasons I would select particular components and values...

Am I mistaken?

"just build an amp, and tell us what you think"
is like saying
"just buy a car... and decide later if that's the right body style, engine, suspension, tires, etc. for your driving needs."
(to draw an analogy)

See what I'm looking for?
My search is more than a year now and you want to have all the answers after 3 days? If you want fundamentals try to read chip manufacturers data sheets.

I still didn't get what you are looking for. I'm not so sure if you know.
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Old 29th January 2004, 01:55 AM   #10
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gainclone is based upon a famous amp built by Junji Kimura, so called the gaincard. now, famous doesnt mean it sounds perfect, just that a couple of guys who hacked open the amp found out that it is using a cheap chipamp after all, and it defies a common theory that "all chipamps sucks". Ive never listened to a gaincard before, but from the reviews, it is quoted to be nicer/ if not as nice as those single ended silver wired bla- bla blah megabuck amps. So, knowing that we can build one of those cheaply instead of going to the store and buy one original, this is probably why caincard clone is so famous. And since we can get the chip for (almost) free, much of the discussions here are regarding the selection of external components to get more superior sounds.
The gaincard is built based on a few design philosophy, mainly that "less is more" meaning: try to minimize the physical components that the music has to go through. Thus the effect: it has very short signal pass and NFB length, only the very necessary external parts are used. Anything that is not critical:throw it away. The designer believes that any extra /unecessary conductors will degrade the sound signal. Of course, you cannot count in the million parts inside the chip itself. Also, contrary to popular engineering, the supply capacitors uses a very small value, so that almost none energy is stored in the caps. This is to the belief that the extra energy stored inside the caps will 'stale' and degrade the signal too. If i can get an oscilloscope, I can be expecting amost AC supply being fed into the amp. The amp relies on the high PSRR to reject ripples from the power supply instead.
All these design philosophies differ from the common/ popular design principles, but the end product still sounds good, and that is why it is so famous among us the DIYs
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