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RSA Predator DAC w/ iPhone? (it used to work)

post #1 of 17
Thread Starter 

Hi,

 

Back in the day, my RSA The Predator DAC used to work with my iPhone and iPad1 when plugged in via the camera connection kit (USB).  After a certain software update (4.3.x I think), that functionality stopped.  The only thing I saw around the same time was that Apple had tweaked the power settings on the USB pins.  RSA says that functionality has never existed and it seemed to be a bitter subject for them.  I didn't really want to argue too hard that it WAS working at one point, they didn't want to hear it.

 

So the question is:  Do any of you know of a way to make it work again?  Different USB <-> Dock adapter?  Different portable DAC?

 

I'm tired of the analog LOD -> Amp option when it shouldn't have to be that way.  Not really expecting a positive answer here, but figured I'd run it by the experts.  Thanks.

post #2 of 17

i would assume it has to do with the configuration of the HOST pin on the PCM270x, the TI USB receiver chip that is popular.  This pin has 2 settings, LOW (100mA) and HIGH (500mA).  As you may know, a low power USB port outputs 100mA and a high power outputs 500mA -- of course these are really dated specs, as in the mid/late 2000s the only thing you could plug a USB DAC into was a computer, and nobody was using a computer old enough to have a 100mA USB port.  So the setting of the pin...if its set to HIGH, then when you plug the DAC into the computer it says "I need 500mA".  And then the iPad is saying "Sorry, goodbye."  Of course, that chip is only using about 35mA, so you don't need to do this.  If the pin is set to low (100mA) then it would be acceptable to a computer or device that will only act as a low power USB port.

 

The Pico DAC uses 97mA, which I intentionally made sure was under 100mA.  To my knowledge, it still works with the iPad, though I don't have an iPad so i haven't tested it.  Maybe it no longer works either.  I dont know if anyone ever got the true story of what Apple did with the current limitations.  If the Pico DAC still works, then I assume it is a 100mA vs. 500mA pin configuration issue.  by the way...since when did the camera connection kit work with an iPhone?


Edited by justin w. - 3/27/12 at 1:03pm

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #3 of 17
If you can find an earlier release of the software (pre4.3x), erase, reformat your hd and reinstall the earlier version of the software on your devices.

The problem seems to be software related and that is probably the only solution for an average user.
post #4 of 17
Thread Starter 

 

Thanks for the reply, Justin.  It makes perfect sense and seems to correspond with the error "The connected USB device requires too much power." as well as whatever Apple did to tweak the USB power settings.  As for the iPhone + camera connection kit:  I may have been mistaken, but I'm pretty sure that after it worked on the iPad 1, I tried it out on my iPod Touch that I had at the time and it worked.  However, I can't confirm that, as the iPod Touch in question is dead now.
 
It makes me wonder if the functionality could be "hacked" by using a similar technique that was found to essentially bypass the "Apple certified Accessory" message.  I think Lady Ada (Adafruit) had a video about it about a year or so ago, it's essentially a resistor or set of resistors soldered to a few pins of the 30 pin dock connector.
 
As for the Pico DAC, I'd be happy to try one on a "new" iPad and iPad2 if you have a loaner.
 
I'm also looking into the Venturecraft GoDAP 4.0's, looks like they may be shipping now :D
 
As for downgrading to 4.3.x, not an option anymore, as I'm using an iPhone 4S, iPad2, and new iPad now.  None of them can be downgraded to that.
 
post #5 of 17

AFAIK, after iOS 4.2 the power limitation was dropped to 20mA. The workaround was to use Dr.Bott's T3Hub which "fakes" the iOS to think that the hub is powered externally. But then your component chain increases - iPad->CCK->T3Hub->USB DAC.

 

As for the VentureCraft GoDAP 4.0 I've used one for about 1/2 year - starting with the Muses 8820 version, then BurrBrown OPA2134, and currently a fully upgraded GoDAP AD8397+RK73+F75. Until recently, the upgraded GoDAP was my primary portable device. Hi personally am very happy with the GoDAP and with a iPod extension cable, I can hook the iPad to the GoDAP too.

post #6 of 17
Thread Starter 

Thanks.  The GoDAP is at the top of my list.  However, the unfortunate part about having to ship it back to Japan (from the US) every time it needs a firmware update... isn't very appealing.  If they have a way to self-update the firmware, I'll order one in a heartbeat.

post #7 of 17

I guess I'm lucky that I just drive or take the subway to VentureCraft's office's whenever I want :D. Yes it's true you have to send it back to them. Having said that, the same is true for the Fostex HP-P1, or with the CLAS too. I actually don't know any portable iDevice DAC/Amps that allow self-update firmwares.

 

 

I thought you may like this pix :D. Middle is mine, the other two are on loan for review/testing.

 

OPA1612 AD8397 Muses9920

post #8 of 17
post #9 of 17
Thread Starter 

Nice Pic :).  I really do like the "all in one self contained unit" approach of the GoDAP, even if it means I'll need a new one later this year when I upgrade my iPhone 4S with whatever is next.  You're very lucky to have them "right down the subway."  I'd also gladly pay extra for whatever device/adapter they need to plug into it to update the firmware, and self update it.  

 

As for the cablejive product, thanks, but I'm not sure what benefit that would have.  It looks like it is designed to help charge your iDevice a little faster than normal.  I don't think it's going to trick the iPhone into thinking a DAC is below the artificial "power limit".  If I want to charge the iPhone fast, I'll hook it up to a 10w iPad adapter.  If I want to recharge my "new" iPad slowly, I'll plug it into the same adapter.  it may be of benefit in that case.

 

 

post #10 of 17
Quote:
Originally Posted by Darwin022 View Post

As for the cablejive product, thanks, but I'm not sure what benefit that would have.  It looks like it is designed to help charge your iDevice a little faster than normal.  I don't think it's going to trick the iPhone into thinking a DAC is below the artificial "power limit".  If I want to charge the iPhone fast, I'll hook it up to a 10w iPad adapter.  If I want to recharge my "new" iPad slowly, I'll plug it into the same adapter.  it may be of benefit in that case.

 

 



My guess is that it still connects the "extra" power to the USB power line from the iPad. The CCK puts the iPad in USB host mode. It still uses the same pins for USB as it did when you charge the iPad. The power "injector" then supplies the DAC with the needed power to run and the iPad won't freak out.

post #11 of 17
Thread Starter 

OK, I could see a possibility of that.  But, I'm still not sure it would work the setup I'm trying to use.  I generally don't put any music at all on my iPad, as it's too big to be a personal music player.  While I CAN easily put it in a pocket (I wear BDU pants daily), it's not something I enjoy doing.  The DAC/Amp idea is supposed to simplify my setup, not add extra adapters to it.  I want to keep this in my pocket so trying to condense the equipment vs. add more complexity, bits, and pieces.

 

In order for this to fit, I'm going to need very deep pockets.  Obviously this is a requirement of continued head-fi membership.  It will be fragile also.

post #12 of 17
Quote:
Originally Posted by Darwin022 View Post

OK, I could see a possibility of that.  But, I'm still not sure it would work the setup I'm trying to use.  I generally don't put any music at all on my iPad, as it's too big to be a personal music player.  While I CAN easily put it in a pocket (I wear BDU pants daily), it's not something I enjoy doing.  The DAC/Amp idea is supposed to simplify my setup, not add extra adapters to it.  I want to keep this in my pocket so trying to condense the equipment vs. add more complexity, bits, and pieces.

 

In order for this to fit, I'm going to need very deep pockets.  Obviously this is a requirement of continued head-fi membership.  It will be fragile also.



Ah I see. The problem is that the iPad is capable of going into USB host mode. The iPhone not so much. Thus limiting your options. 

post #13 of 17
I am currently using the first gen IPad with the latest IOS 5.1 > camera kit > Pico amp with DAC > LCD 2 rev 2 and it works great.

I just received the Pico amp as an upgrade to my Fiio E7.

There is no comparison the Pico it is a huge step up, in terms of clarity, tonal colors, soundstage and rhythm/drive. It's a great product.
post #14 of 17

Just got the new iPad and the camera connection kit.  Plugged in the Pico DAC, fired up YouTube - it works!  

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #15 of 17
Reawakening the zombie thread.

Anyone tried the Predator with an iPod Touch / iPhone running iOS 7? Do you get the digital out from that?
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