Curious about 3 channel amps...
Oct 7, 2009 at 2:30 AM Post #46 of 64

rds

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Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
Complete and utter rubbish!

For Grado to owe Chy Moy for their design, you'd first have to credit Chu Moy with inventing the non-inverting operational amplifier.

It's not a datasheet configuration, it's a textbook configuration. It's as absolutely generic as it can possibly get.




Apparently you don't understand engineering ip very well. Most engineering patents involve creating a unique system out of existing components. I'm not claiming that Chu Moy invented the headphone jack, potentiometer, capacitor, battery, resistor, or opamp. I'm saying he put them together to create the cmoy, and that the grado ra-1 is a cmoy.

Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
The key phrase here being "free exchange of ideas." A free exchange must be mutual. Otherwise, it's not an exchange, it's just plain taking. And I don't recall Grado being a willing party to any exchange of ideas with regard to the RA-1.

I agree that it's silly to bust someone's balls just because they want to build an RA-1 clone for themselves. But don't make out like Grado was under some sort of obligation to share their design with others.

se



Again you completely miss the point. Grado can claim they own the ocean. That's not going to stop me from swimming in it. If I claim to own the air are you then 'taking' it by breathing? When I say free exchange of ideas I mean that we don't try to hide ideas from each other. Therefore I think it is against diy ethic to say people shouldn't be allowed to know the details of a reverse engineered cmoy whether it was made by grado, some random person, or god herself.

FYI, the exchange between the person who [legally] reverse engineered the ra-1 and posted the details, and anyone who desires to see them is a free exchange.
 
Oct 7, 2009 at 2:43 AM Post #47 of 64

Aynjell

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Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
Are you wanting to learn how to build your own power supply, or do you simply want to avoid using batteries?

If the latter, just use that little Elpac power supply I referred to in a previous post.

se

nodualxlr.gif



Both. I want to avoid using batteries, but the elpac might only last me for the duration of my CMOY like designs. I highly doubt an elpac is good enough for the M3 (although it is suggested as a possible power supply for the unit), but something tells me it'll starve the circuit and might mud things up a bit... at least enough that it'd destroy the investment I made on the parts for the circuit. I just don't see it as being a good solution for the future.
 
Oct 7, 2009 at 2:58 AM Post #48 of 64

Steve Eddy

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Quote:

Originally Posted by rds /img/forum/go_quote.gif
Apparently you don't understand engineering ip very well. Most engineering patents involve creating a unique system out of existing components. I'm not claiming that Chu Moy invented the headphone jack, potentiometer, capacitor, battery, resistor, or opamp. I'm saying he put them together to create the cmoy, and that the grado ra-1 is a cmoy.


Again, complete and utter rubbish!

There is nothing unique about the CMoy. Headphone amplifiers using batteries and opamps are nothing new. You can find references to them in Wireless World, EDN, and semiconductor app notes going back to the 70s.

Quote:

Again you completely miss the point. Grado can claim they own the ocean. That's not going to stop me from swimming in it.


I never said it would. Again, I've said more than once already that there's no protected intellectual property in the RA-1.

Quote:

When I say free exchange of ideas I mean that we don't try to hide ideas from each other. Therefore I think it is against diy ethic to say people shouldn't be allowed to know the details of a reverse engineered cmoy whether it was made by grado, some random person, or god herself.


Again, there is nothing unique about the CMoy.

se

nodualxlr.gif
 
Oct 7, 2009 at 2:58 AM Post #49 of 64

rds

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Quote:

Originally Posted by Aynjell /img/forum/go_quote.gif
Both. I want to avoid using batteries, but the elpac might only last me for the duration of my CMOY like designs. I highly doubt an elpac is good enough for the M3 (although it is suggested as a possible power supply for the unit), but something tells me it'll starve the circuit and might mud things up a bit... at least enough that it'd destroy the investment I made on the parts for the circuit. I just don't see it as being a good solution for the future.


As mentioned earlier, the AMB mini 3 seems like a really good fit. The design and case integration are just excellent. It can run on off its 9V battery on the go and a wallwart at home (which also charges the battery).

Glass Jar Audio sells the complete kit with power supply for $88. You really can't go wrong.

[Finally gave that ignore feature a try
smily_headphones1.gif
]
 
Oct 7, 2009 at 3:17 AM Post #50 of 64

Steve Eddy

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Quote:

Originally Posted by Aynjell /img/forum/go_quote.gif
Both. I want to avoid using batteries, but the elpac might only last me for the duration of my CMOY like designs. I highly doubt an elpac is good enough for the M3 (although it is suggested as a possible power supply for the unit), but something tells me it'll starve the circuit and might mud things up a bit... at least enough that it'd destroy the investment I made on the parts for the circuit. I just don't see it as being a good solution for the future.


Well, the M3 uses a single supply so you wouldn't use that particular Elpac supply anyway. But neither your Grados nor most any other headphone is going to suck 240 mA out of a headphone amp. And even if they did, they'd be toast in rather short order.

Another simple option would be to use an AC wall wart of sufficient voltage and capacity and do your rectification, filtering and any voltage regulation inside the amp chassis.

se

nodualxlr.gif
 
Oct 7, 2009 at 3:21 AM Post #51 of 64

Steve Eddy

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Quote:

Originally Posted by rds /img/forum/go_quote.gif
[Finally gave that ignore feature a try
smily_headphones1.gif
]



Great. Now try the "grow up" feature.

There's nothing more childish and immature than someone announcing in public they're putting someone on ignore instead of simply ignoring them.

se

nodualxlr.gif
 
Oct 7, 2009 at 3:47 AM Post #52 of 64

Aynjell

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Quote:

Originally Posted by rds /img/forum/go_quote.gif
As mentioned earlier, the AMB mini 3 seems like a really good fit. The design and case integration are just excellent. It can run on off its 9V battery on the go and a wallwart at home (which also charges the battery).

Glass Jar Audio sells the complete kit with power supply for $88. You really can't go wrong.

[Finally gave that ignore feature a try
smily_headphones1.gif
]



I was impressed by this kit until I saw that the fancy end panels that come with it are an extra 40$. I may be misreading this, though.

What external power supply should I be using for this?
 
Oct 7, 2009 at 4:06 AM Post #54 of 64

Aynjell

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Quote:

Originally Posted by rds /img/forum/go_quote.gif
Yes, the panels are a little pricey. But that is just how it goes with custom panels.
Fortunately, amb has printable pdf templates provided on his website so you can drill the panels yourself.



That wouldn't be hard at all, but dammit I wish those slick looking metal panels pictured weren't with the only picture they show, I hate it when companies do that.
 
Oct 7, 2009 at 6:42 AM Post #56 of 64

NelsonVandal

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There aren't that many ways to implement an opamp. The differencies lies in the choice of opamp, and the way the return currents are handled (you can call it the power supply if you want) - which IMO is just as important as the L/R channels: resistors/capacitors, batteries, IC or discrete railsplitter, IC or discrete regulators, transformer midpoint etc.

IMO the ground channel concept works as advertised and is superior to passive circuitry. It might not be an improvement over a regulated low impedance PSU, but it's simpler, and it can be battery operated. Another virtue is the ability to tweak the ground channel in an easy way to a slightly different sound from the L/R channels to get a perfect blend. It's also cheaper and smaller than a passive ground since the capacitors don't sink/source the return currents - large "audio grade" capacitors aren't needed.

Regarding the intellectual property of Grado, I agree to that it's impolite to publish a sponsors schematic, but at the same time I think it's good to show the world the nature of this business. It's just as much attitude as there are science and tecnology.
 
Oct 7, 2009 at 7:31 AM Post #57 of 64

00940

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Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
Another simple option would be to use an AC wall wart of sufficient voltage and capacity and do your rectification, filtering and any voltage regulation inside the amp chassis.


Old printer power supplies are what you want. You easily find 30VDC (unregulated) or 24VAC supplies coming from the typical HP printer of the 90's. And those aren't smps but good old transformers.

At most, it will cost you 2$.
 
Oct 7, 2009 at 1:20 PM Post #58 of 64

Aynjell

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Let's say I have two op amps in a sequence, is the capacitor that serves as an output buffer required for the first op amp required, or can I just setup the buffer on the second op amp?

I was thinking about it last night, you could make 2 cmoy boards and use the same dual op amp twice, once for each channel, or if you wanted to you could send the output of the left side of left, to the right side of right and then send that to the jack, and vice versa. is this a terrible idea or could it work?

Also, let's say I did such a setup, for example, if I did a gain of 1, and then a gain of 2, that'd give me a total gain of 3, or 4? I wasn't sure if I was multiplying or not.

Also, the way i understand it is the amps with 3 channels pull the ground through the third (or if fully balanced, both grounds) through the third and/or fourth board. Does the ground signal pass through the eletrical part of the amplifier or the signal part of the amplifier?
 
Oct 7, 2009 at 3:01 PM Post #59 of 64

Steve Eddy

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Quote:

Originally Posted by NelsonVandal /img/forum/go_quote.gif
IMO the ground channel concept works as advertised and is superior to passive circuitry.


But it doesn't entirely work as advertised. It's advertised as bypassing ground. It doesn't. That's a myth.

Quote:

It might not be an improvement over a regulated low impedance PSU, but it's simpler, and it can be battery operated.


A regulated low impedance PSU can be as simple as a pair of three terminal regulators.

And the ground channel doesn't provide any regulation of the supply rails. So unless you're powering your circuit from batteries, you'll get all the ripple voltage on the supply rails that you'd get with any unregulated AC power supply.

Quote:

Another virtue is the ability to tweak the ground channel in an easy way to a slightly different sound from the L/R channels to get a perfect blend.


A perfect blend of what?

Ideally the ground channel behaves as a low impedance path to ground. What "tweaking" is there to do on a low impedance path to ground?

Quote:

It's also cheaper and smaller than a passive ground since the capacitors don't sink/source the return currents - large "audio grade" capacitors aren't needed.


That's incorrect. All of the current emanates from and returns to the power supply caps. You'd need just as large capacitors with a ground channel as without.

As I said in another thread on this issue, the return currents don't just spill out onto the floor or evaporate into the air.

se

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Oct 7, 2009 at 3:02 PM Post #60 of 64

Steve Eddy

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Quote:

Originally Posted by 00940 /img/forum/go_quote.gif
Old printer power supplies are what you want. You easily find 30VDC (unregulated) or 24VAC supplies coming from the typical HP printer of the 90's. And those aren't smps but good old transformers.

At most, it will cost you 2$.



Good idea!

se

nodualxlr.gif
 

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