[audioengr]

does anyone know the difference between Spartan6 FPGA and XMOS?  Is DSD support the only difference, does one sound better than the other?

DSD is a function of the design, not the chip.  Both of these are capable.  in theory the same designer can make them sound identical.  The jitter depends on the ancillary design stuff, the kind of stuff that I do for instance.

Steve N.

[preproman]

USB power?

Does the OR5 / OR6 need the power from the USB cable?  Can I use a USB cable with no power leg it in?

[audioengr]

USB power?

Does the OR5 / OR6 need the power from the USB cable?  Can I use a USB cable with no power leg it in?

OR5 does not need +5
OR6 will need it.

Steve N.

[DaveBSC]

OR5 does not need +5
OR6 will need it.

Steve N.

Now that is a surprise. Most of the high-end converters (and DACs that make an attempt to take USB seriously) make a point to completely avoid any reliance on the Vbus because it's full of noisy crap. That also lets you cut the supply off using the switch on the SoTM card, or the Short Block, etc. I've always knocked Berkeley for powering the receiver half of their Alpha USB using the Vbus, even if its supposedly separated from the output half via opto-isolators or however they did it.

I've also seen plenty of claims about devices that do use Vbus power being able to "clean it up" via regulators, and it never works. All of them are greatly improved when the Vbus line is substituted with another 5V supply from a battery, or the iUSB, or similar devices.

What's the reason for the change?

[audioengr]

Now that is a surprise. Most of the high-end converters (and DACs that make an attempt to take USB seriously) make a point to completely avoid any reliance on the Vbus because it's full of noisy crap. That also lets you cut the supply off using the switch on the SoTM card, or the Short Block, etc. I've always knocked Berkeley for powering the receiver half of their Alpha USB using the Vbus, even if its supposedly separated from the output half via opto-isolators or however they did it.

I've also seen plenty of claims about devices that do use Vbus power being able to "clean it up" via regulators, and it never works. All of them are greatly improved when the Vbus line is substituted with another 5V supply from a battery, or the iUSB, or similar devices.

What's the reason for the change?

Necessaryfor some of thecircuitsforgalvanIc isolaton.  Will not affect jitter, only improve it.

Steve N.

[preproman]

OR5 does not need +5
OR6 will need it.

Steve N.

I agree with DaveBSC on this.  This is strange.  Why go backwards?

[audioengr]

I agree with DaveBSC on this.  This is strange.  Why go backwards?

I don't consider it a step backwards.  With galvanic isolation, the Short-Block will not be necessary.  Galvanic isolation is a bit better than a filter I predict.  Jitter will be just as low as the OR5.

Steve N.

[DaveBSC]

Alpha guts exposed. Apparently their method of isolating the input side of the Alpha USB from the output is an Analog Devices ADuM chip, plus a shield that's part of the chassis. The clocks are Crystek CCHD-957s. Steve, I'm curious if you think the OR6 will be improved by adding something like the iUSB or a 5V battery inplace of computer power. It seems to make a significant improvement in every other design I've seen that uses Vbus power, including those with galvanic isolation.

[audioengr]

There are significant differences in my design.  Looking at the BADA design, I don't see any signs of true reclocking across the isolation interface.

I will be using a faster isolation chip too.

I fully expect the +5V in the cable to not matter and the cable will not matter either.  This is what I already have with my Synchro-Mesh, so I know it can be accomplished.

Steve N.

[preproman]

So let me make sure I understand here.

There will be no need for my SOtM PCIe USB card to have it's own power supply?  And no need for a fancy pants USB cable?

Also will the OR6 still be housed in a black enclosure?  Or will there be a choice of colors?

[audioengr]

So let me make sure I understand here.

There will be no need for my SOtM PCIe USB card to have it's own power supply?  And no need for a fancy pants USB cable?

Also will the OR6 still be housed in a black enclosure?  Or will there be a choice of colors?

Right, the USB interface should not matter anymore.  I plan to offer the OR6 in a silver chassis with the Overdrive type front panel.

Steve N.

[JPS]

Hi Steve,

OR6 sounds very promising if it can finally eliminate the effects of USB circuitry and cabling.

Will it use the same outboard power supply as OR5?

Best regards,

Jean-Pierre

[audioengr]

Hi Steve,

OR6 sounds very promising if it can finally eliminate the effects of USB circuitry and cabling.

Will it use the same outboard power supply as OR5?

Best regards,

Jean-Pierre

Same supply.  Plan is that OR5 will be upgradable.

Steve N.

[jult52]

Steve - I am thinking of replacing the pulse transformer on my DAC, which is not one of your products.  How do you evaluate pulse transformers?  Do you have any recommendations as to readily-available pulse transformers, such as the Lundahls or those from Scientific Conversion, Inc?

[audioengr]

Steve - I am thinking of replacing the pulse transformer on my DAC, which is not one of your products.  How do you evaluate pulse transformers?  Do you have any recommendations as to readily-available pulse transformers, such as the Lundahls or those from Scientific Conversion, Inc?

Both of these are good quality.  The important thing is to replace it with the same type, as in 1:1.  If it has a shield, this must be grounded.

Most of the time, the bigger problem is that the resistors used to match impedance are the wrong values, or the resistor network is not an optimum one.

Steve N.

[pzull]

Hi,

Does anyone know if the Apogee Minidac can be used with the SM with OTL mod? I searched the web but couldn't find any info on whether the minidac has input transformers.
I'm about to get the SM but unsure if I can go with OTL option.

Thanks in advance for any advice

[jimiles]

I recently sent my OR5 to Steve for the OTL mod and it does not disappoint.  The improvements are easily as significant as adding the Dynamo power supply.  Depth, layering, separation, (insert buzzword here), all took a step forward. I most appreciate the tonal realism. Brass instruments are now extremely realistic. Also, micro dynamics exhibit finer gradation which is particularly noticeable on piano.   

My Aqua La Scala Optologic sounds so fantastic fed by the OR5 OTL that I haven't even been tempted to try the Aqua's onboard USB. You don't need an expensive DAC to hear the differences, though.  I also own an uber-modded Eastern Electric DSD Supreme and the OTL mod is plainly audible there, too. 

If you are on the fence about whether the OTL mod is worth it, I can assure that it is. 

Jake