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Majestic DAC |
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Drewan77
Senior Member Joined: 25 May 2013 Location: Chester,England Status: Offline Points: 1544 |
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Older than I once was, younger than I'll be
............................. Andrew |
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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So Fritz, if I want to buy the MacBook Pro - the one that puts out 192 kHz optical (since September 2013), which socket is used? And what cable do I need?
And Ash and Andrew, the only difference on the USB input is that it doesn't make use of the bus power, only the signal wires are connected inside the Majestic, otherwise the USB input stage is identical to the Bitzie. Instead of the digital (TTL) output being interfaced to the optical driver and the transformer coupled coax out, it goes (via the front panel switch) straight to the Wolfson transceiver where the clock is cleaned up (reclocked) and turned into I2S which is sent to the Wolfson DAC chip. Therefore it should work with the Samsung S3. Maybe we should fit a felt mat on top of the Majestic to sit the S3 on? Obviously we cannot use a "dock" as the word is owned by Apple... I wonder how much in royalties shipyards have to pay? |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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According to http://www.jensign.com/SPDIFLink/index.html I got my calculations wrong - in fact way out.
It helps to have the facts first and here they are courtessy the above site: "The S/PDIF digital audio interconnect format is described by a sampling rate of the 64-bit audio data frames. Each 64 bit frame contains a single audio sample for both the left and right channels along with various status bits. Therefore for the sampling rates of 48kHz and 96 kHz discussed here, the information bit rates are 3.072 and 6.144 Mbit/sec respectively." Therefore 192 kHz will require a data transfer rate of 12.2288 Mbps. The limiting factor is the fibre-optic ("Toslink") receiver. The Majestic uses a 15.5Mbps receiver which is around 25% more than required. So, it still looks feasible that the 192 kHz sampling rate from the MacBook Pro will interface with the Majestic DAC via optical cable AND be processed at 192 kHz through the DAC. Producing a test jig to prove it by measurement may not be all that simple. The regular way of converting coax level to the TTL level required to drive a Toslink type IR transmitter is to make use of an hex inverter logic IC. This would have to operate at more than 12MHz requiring careful selection of logic family, but prototyping on veroboard would introduce stray capacitance and possibly slow it to below the desired pulse rate. It could be possibly cheaper to buy a coax to optical converter, which exist, but may not be capable of reaching 192 kHz. Why AP didn't foresee the rise of 192 kHz optical transmission is a question for AP, and I will ask. |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Aussie Mick
Senior Member Joined: 21 Feb 2014 Location: Bendigo Aust. Status: Offline Points: 1091 |
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Is the avoiding-volume-control issue as simple as using the fixed level RCA outs?
Mick. |
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Drewan77
Senior Member Joined: 25 May 2013 Location: Chester,England Status: Offline Points: 1544 |
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Older than I once was, younger than I'll be
............................. Andrew |
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Drewan77
Senior Member Joined: 25 May 2013 Location: Chester,England Status: Offline Points: 1544 |
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Older than I once was, younger than I'll be
............................. Andrew |
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Ash
Senior Member Joined: 18 Mar 2013 Location: Dorset Status: Offline Points: 4334 |
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Thank you for checking that for me Andrew.
No docks please! I can't stand those proprietary things... So because of the regulated power supply, even Majestic USB should be a lift over Bitzie USB. Many thanks.
Edited by Ash - 23 Jul 2014 at 9:05am |
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