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The first balanced ultra-portable headphone amp in the world....

Dec 14, 2009 at 8:37 AM Post #61 of 902
Quote:

Originally Posted by ety0820 /img/forum/go_quote.gif
OH~~~That`s goood news!
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but i have question.Can single end cable transformed to balanced cable by using
adapter??


if you did, you would be losing all the benefits of using a balanced amp, though you can go from a balanced connector to single ended with an adaptor for other amps that dont have balanced outputs.
 
Dec 14, 2009 at 10:16 AM Post #62 of 902
Months before this thread was started by Ray, I already had the concept in mind for a balanced "portable" amp to drive the best IEMs. I'm glad an entrepreneur and designer has already begun engineering one. If it will be priced within budget, I will be very happy to consider buying one in the not-so-near future. I've already purchased an RE0 and Icon uDAC, and am anticipating to be satisfied with this setup for a long time before considering something that might share the caliber of Westone or JHA's flagship products.
 
Dec 14, 2009 at 12:07 PM Post #63 of 902
the cable indeed needs to be decides on. i would hate a new breed of balanced portable amps to come along with no support at all for a standard connections. why not dual stereo mini? it is pretty much TRS but smaller and most balanced sources in the professional world use XLR or TRS.
 
Dec 14, 2009 at 1:27 PM Post #65 of 902
Quote:

Originally Posted by SoupRKnowva /img/forum/go_quote.gif
if you did, you would be losing all the benefits of using a balanced amp, though you can go from a balanced connector to single ended with an adaptor for other amps that dont have balanced outputs.


oh.....thanks for explaining
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that`s really true.

I don`t have any balanced IEM and custom IEM like ue 11pro,ES3X,or JH13. Is balanced IEM only for custom IEM???
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Dec 14, 2009 at 1:59 PM Post #66 of 902
Quote:

Originally Posted by Sasaki /img/forum/go_quote.gif
I am interested in this as I have JH13. At least no need to worry about JH customs.
But I am a bit curious about volume pot. If this is fully balanced, the volume pot must support 4ch but this unit is not looks like so..


Hi Mr. Sasaki... There are two ways you can design the balanced amp when dealing with single ended input signal. One of them is taking the SE signal & running it through a volume control that has two sections only, one for the left the other for right channels, this way at least you are dealing with a volume control that has less problem in tracking & is easier to match the two sections than the one with four sections, as the one with four sections is almost impossible to match all four sections together. Going back to the pot with two sections, the output of the pot, Wiper, is going into a gain circuitry to determine the gain needed, then the SE signal is going to the phase splitter where the SE signal is split into two signals mirror image of each others but with the 180 degree out of phase, thus creating your positive & negative signals needed to go to the last stage which is the buffer. Margin of error is way less when dealing with a pot as good as the Panasonic used in the Protector, as it is easy to match the two sections as we said above.

The second choice would be, to feed the SE signal to a phase splitter, first, to get the two mirror image signals, the positive & the negative, then running the two signals of the left channel & the two siganls of the right channels, four in all, into the FOUR sections of the volume control, which is so hard to find well matched, & then out of the four wipers of the volume control to four buffers.

I believe the first choice would be a better one.
Ray Samuels
 
Dec 14, 2009 at 2:56 PM Post #68 of 902
Quote:

Originally Posted by itsborken /img/forum/go_quote.gif
Why not adopt the digital volume advances into this balanced amp to totally eliminate the 'well matched' issue? Small is good but I'd trade size for 'done right'.


Most of the digital volume controls are designed with a single power supply in mind. That means in order to design an amp, you have to implement INPUT & OUTPUT capacitors in the signal path. Doing that means the sound is no longer pure with out colorations. I do not like to put caps in the signal path of any of my amps. I had talked to many technical engineers of many manufacturers of digital volume controls, non of them ever heard of very sensative in ear monitors, as to few who replied that these digital volume controls were not designed for a critical listening specially with IEMs. They were designed for cars, computers & other portable devises where regular phones were used & a single power was the main supply. The best design is done when a dual power supply is implemented thus the need for caps in the signal path is no longer an issue.
Ray Samuels
 
Dec 14, 2009 at 5:33 PM Post #69 of 902
TI's PGA2320 was designed for professional and high-end consumer audio. The analog section operates from a dual supply (+/- 4.5 to +/- 15 volts) and can therefore be direct coupled. In addition, it can also provide up to 31.5dB of gain, killing two birds with one stone, requiring just an output buffer for driving headphones.

se
 
Dec 14, 2009 at 5:51 PM Post #70 of 902
Quote:

Originally Posted by Ray Samuels /img/forum/go_quote.gif
That means in order to design an amp, you have to implement INPUT & OUTPUT capacitors in the signal path....

..,.I had talked to many technical engineers of many manufacturers of digital volume controls, non of them ever heard of very sensative in ear monitors, as to few who replied that these digital volume controls were not designed for a critical listening specially with IEMs. They were designed for cars, computers & other portable devises where regular phones were used & a single power was the main supply.


So how did you do it in the Shadow, and why couldn't that also be done here?
 
Dec 14, 2009 at 7:21 PM Post #71 of 902
Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
TI's PGA2320 was designed for professional and high-end consumer audio. The analog section operates from a dual supply (+/- 4.5 to +/- 15 volts) and can therefore be direct coupled. In addition, it can also provide up to 31.5dB of gain, killing two birds with one stone, requiring just an output buffer for driving headphones.

se


Hey Buddy...
As you could see that we are dealing with a small battery with 3.7 volts for portable use with IEMs. The chip you indicated in your post works with Plus & minus 15 volts & it's Q is 16 ma. which it will drain the battery just by sitting idle. WE don't have that kind of voltage on board even though we can generate it on the expense of draining the battery, at the same time this chip does not work by it self it requires a controller that needs to be fed power.
Ray Samuels
 
Dec 14, 2009 at 7:43 PM Post #72 of 902
Wow, can't believe it, just got in touch with the outlet that supplies the connectors that is implemented in the IEMs cable, see picture on the first page, they told me that some one purchased all their stock. Can't believe it, I have to find some other source for them now.
Here is the P # of the connector & its pins terminations.
Terminating the cable to the pins as posted below, will make your IEMs work correctly with the Protector balanced amp.

The part # for the cable connector is 191J-E Manufactured by Kobiconn.
Pins configuration is ....
Left channel, pin #1 is positive
Left channel, pin #3 is negative

Right channel, pin #2 is positive
Right channel, pin #4 is negative

Ray Samuels
 
Dec 14, 2009 at 8:16 PM Post #73 of 902
Speaking of Kobiconn, why not use their TRRS 2.5mm SMT jack combined with their matching plug?

That would get around the problem of someone sticking a 3.5mm plug into it.

se
 
Dec 14, 2009 at 8:23 PM Post #74 of 902
Ray:

Steve was directly challenging your statement that a high-end consumer audio chip does not exist that operates from a dual supply and can be direct coupled. The PGA2320 achieves all three of these things. The point wasn't whether or not this could be achieved in an ultra portable, but whether or not something like this chip even exists, which you said did not.
 
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