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MDAC First Listen (Part 00101001)

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flambeur said:
Hey John, is this offer also open for others? I would be interested in a pair (maybe another one later?) in black for use with my black FDAC (balanced of course).

Cheers, flambeur
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flambeur,

I have a basement full of these Monoblocks I originally purchased as donor units for the VFET amplifier project, but now the VFET amps have there own costumed designed chassis I should turn these units back into cash.

Each MonoBlock is GBP450 (I'll upgrade the units for either Balanced of Single ended use by removing the front end 5534 opamp circuit).
 
JohnW said:
MDAC does not, but the FDAC with its Isolated USB section will.
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John, thinking about the limitations of galvanic isolation as you explain it in your earlier post, is it worth the price of using the sending device's 5v supply and ground? If the isolation only works for Dc blocking and earth loops then it would seem as though you might be letting more in than you keep out. Apologies if I have misunderstood your earlier post.

If you are going for the full width chassis with the fully isolated power supply would it be better to use a separate isolated supply at the Dac end to power the isolated receiver section?
 
ChrisPa said:
My understanding is that amplifying the current output of an MC cartridge removes most of the need for eq
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Chris,

Surely not the RIAA EQ? I cannot see how this would be the case - although I could understand that you would not need to worry about HF loading of the MC Cartridge, although I've sure a HF Zobel network would be a good idea.

Does anyone have Broken / Dead MC cartridges I could measure there electrical characteristics so I can create accurate Spice models.
 
adamdea said:
John, thinking about the limitations of galvanic isolation as you explain it in your earlier post, is it worth the price of using the sending device's 5v supply and ground? If the isolation only works for Dc blocking and earth loops then it would seem as though you might be letting more in than you keep out. Apologies if I have misunderstood your earlier post.

If you are going for the full width chassis with the fully isolated power supply would it be better to use a separate isolated supply at the Dac end to power the isolated receiver section?
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I'll filter the Host devices 5V supply before powering the isolated circuits within the FDAC.

An isolated supply would have a level of capacitance at HF/RF so would act as an extra transmission path...
 
fusion5 said:
A single USB 2.0 port allows for a maximum current of 500mA.
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OK - but I'm a little perplexed by that. The R Pi2 for example gets its power through a micro USB connector and the recommended PS is 5v at 2A if you have peripherals attached. Even without it needs more than 500 ma. What am I missing?
 
iansr said:
OK - but I'm a little perplexed by that. The R Pi2 for example gets its power through a micro USB connector and the recommended PS is 5v at 2A if you have peripherals attached. Even without it needs more than 500 ma. What am I missing?
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Don't think of it as a normal USB (data) connection. They are merely using the micro USB connector for the power supply.

Edit: A unit load is defined as 100 mA in USB 1.x and 2.0, and 150 mA in USB 3.0. A device may draw a maximum of five unit loads (500 mA) from a port in USB 1.x and 2.0, or six unit loads (900 mA) in USB 3.0. (Source: Wikipedia)

Edit2: In July 2012, the USB Promoters Group announced the finalization of the USB Power Delivery ("PD") specification, an extension that specifies using certified "PD aware" USB cables with standard USB type A and B connectors to deliver increased power (more than 7.5 W) to devices with larger power demand. Devices can request higher currents and supply voltages from compliant hosts – up to 2 A at 5 V (for a power consumption of up to 10 W), and optionally up to 3 A or 5 A at either 12 V (36 W or 60 W) or 20 V (60 W or 100 W). In all cases, both host-to-device and device-to-host configurations are supported. (Source: Wikipedia)

Apparently there is a special specification for this high currents. But make no mistake, RPi2 will most likely burn out most USB ports if connected with a USB A to micro USB cable.
 
JohnW said:
I'll filter the Host devices 5V supply before powering the isolated circuits within the FDAC.

An isolated supply would have a level of capacitance at HF/RF so would act as an extra transmission path...
Click to expand...

My USB card is powered by a linear power supply. Does the FDAC benefit from this?
 
cstanpfm said:
There is also a review of the jitterbug in the latest issue of Hi-Fi News.
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It comes with the seal of unimpeachable engineering integrity of a firm who have for years been selling a range of usb cables with identical geometry but differing degrees of jewellery as materials.
 
adamdea said:
It comes with the seal of unimpeachable engineering integrity of a firm who have for years been selling a range of usb cables with identical geometry but differing degrees of jewellery as materials.
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Very droll, but those cable sales keep the industry afloat, apparently!
Keith.
 
Touché ,but the Weiss optical cables aren't quite like ordinary cables are they, containing as they do an optical transmitter and an optical receiver, allowing you to take an AES electrical signal, convert it to optical, which is transferred via a glass optical cable to the optical receiver and then converted back to electrical AES.
Overkill perhaps but an excellent way to isolate your dac.
Keith.
 
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