Fostex HP-P1 or RSA SR-71?? - Page 2

The LOD provides analog line out? In Jude's review of the Algorhythm Solo he says the digital signal is taken, or is that a function of just those types of devices?

Unless using something specifically designed to extract a digital signal from an i-device, (HP-P1, CLAS, Wadia 170i, Onkyo ND-S1, etc), the LOD will supply an analog signal that simply bypasses your device's internal amp.  Digital conversion is still done internally.  

 

Like ll Mostro said, only a handful of very expensive, specially designed DAC/amp is capable of extracting digital signal from iDevice. By hard definition, the cable they used are not LOD at all, since they are not extracting line-out signal. These are more like 'DOD', that's Digital-Out Dock.

Basically there are 3 types of signal that you get from your iDevice. 1) Amped signal from your heaphone jack, 2) Line out analogue signal that you get from your dock which feeds usually to a standard audio mini plug which needs to be amped and 3) A digital LPCM signal that you get from buying a license from Apple to decode this signal which comes out from the dock and terminates in a standard USB plug.

 

This third type bypasses the use of any audio functionality of the iDevice and instead just uses it as a mass storage device to feed out digital signal. The signal is then processed on a DAC chip located on a (HP-P1, CLAS, Wadia 170i, Onkyo ND-S1, etc) which then gets amplified etc. The whole point is to bypass the onboard DAC chip of the iDevice and decode this signal using a higher spec setup for better sound quality.

 

iDevice decoding from above mentioned hardware is not compatible with standard PC USB output and so they are mutually exclusive devices.

 

 

 

Edited by Lillee - 3/2/12 at 7:24pm

 

The analog line-out still uses an amp (opamp) within the iPod though, right?

 

Nope it is exactly that, a line out straight from the inboard DAC and bypasses the amp. If you listen to this line out on earphones it will be nearly inaudible

 

What, so you can't actually hear anything from the line-out, unless you connect an amp?

 

Most line-outs, you can listen to directly.

 

 

It's just an analogue signal from your ipod DAC and bypasses the amplifier, that's the whole point of the line out.  It will be very low volume. It's OK maybe for headphones with say 25 ohm resistance and are easy to drive but for 250 or 600 ohm heaphones you won't hear anything.

 

Once the iDevice has detected a line out plugged in the software volume control which controls the onboard amp is disabled completely. It's the equivalent of a line out of a dedicated CD player. There is no amplification circuit to speak of so the volume is low and has no volume control.

 

I run my line out to my Luxman 2 channel amplifier driving my Kef floorstanders and the volume has to be turned up pretty high to be at normal listening volumes.

Edited by Lillee - 3/3/12 at 12:43am

Sure, I'm just a bit skeptical because the iPhone doesn't do that, and you need an amp to hear music, whether an opamp, or integrated into the D/A itself.

 

 

Yes it does, I am talking about any iDevice. I don't yet own an iPod and was referring to my iPhone 4S in the above posts.

 

It's not a difficult concept. The mini jack at the top of the phone/ipod is an amped output. A line out dock connector is to feed external amps and bypass the onboard amp. A Fostex HP-P1/ CLAS etc decodes the digital data and bypasses everything audio on your iDevice. This is by design.

 

EDIT: It'd be pretty silly if they made the line out dock exactly the same amped signal as the mini jack wouldn't it?

Edited by Lillee - 3/3/12 at 12:52am

 

The line-out (RCA) on a dedicated CD player, still uses an OpAmp chip behind the RCA, you are listening to an amp.

 

 

     Quote:

Yes, I think it's silly. =/
 

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You are correct in points 1 and 2.
 

Edited by kiteki - 3/3/12 at 1:19am

If I was you,I'll consider the algorhythm solo DAC and buying a extra amp for the combo.By the way,I surfed the Cypher Labs's site and I found that HP-P1 couldn't support the iPad at all.

 

And all I read from some impressions,reviews and comparisons from internet,I found that the built-in amp of HP-P1 wasn't the powerful one,some guys suggested using line-out and plugging in a extra amp will make the all combo more amazing,and I know that will make your wallet more slacked,too.So I thought the CLAS will also be the good choice,but you will have to buy a amp for the CLAS.

 

I think you need to do some more research to satisfy yourself, I am 100% certain that the line out dock on iphone/ipod bypasses it's onboard amp. This is how an iMod from Red Wine Audio works and the entire point of an iMod.

 

Sorry to original poster for hijack
 

 

Edited by Lillee - 3/3/12 at 1:40am

I am just trying to help.