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MDAC First Listen (part 00101100)

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JohnW said:
What Gain and Loading is most "common"?

In theory its a simple matter of selecting input loading resistors and capacitors for the MM stage - but really the quality of the the FDAC is directed towards higher-end MC cartridges.

The Lundahl transformers look interesting but are more costly when compared to the CineMag parts - so I'm keen for anyone's experience with MC transformers.

I'm drifting towards using the Lundahl transformers as I can design a dual footprint PCB allowing owners to optimise the MC stage with the LL1931/41 or the LL1933/43 series, or even the silver versions. The secondary loading resistor can be a "socketed" Vishay Film type for fine tuning.

Suggestions appreciated...
Click to expand...

Timely PFM thread: http://www.pinkfishmedia.net/forum/showthread.php?t=181374
 
I don't understand it, I'm not following this thread as I have better things to do right now but what's the status right now? it's been so long, will I get an update by email or something? what are all these new things right now, what do I need to pay for? I paid for all 4 stages..
 
Hi dadab12,

Just trying to understand...

You don't understand what's going on because you have better things to do but you're asking that those of us that do keep up to date (and perhaps, by your definition, don't have better things to do) to update you...?
 
Dadab12,

Your payments are up to date, with nothing to pay until early next year when we start the production of the Analogue PCB.

Asides from posting updates here, we will Email once we progress to the next payment / production stage.
 
JohnW said:
Hossen,

The design for the FDAC has progressed to where I'm finally starting on the FDAC's L3 ADC section :) - so I'm defining its input structure.

The Phono stage is simply a section of the ADC input Gain stage - especially when using a transformer for the low noise MC input. The "Phono stage" is not a separate project, but an integral part of the ADC gain block.

Dont worry - really no VFET power stage for FDAC, it was just an "off the cuff" discussion about future direction once these current projects are completed - hence the VFET V2 description :)

The ADC input has an selectable RIAA filter (a relay and a handful of passive components) - the low noise MC gain stage is handled by the step up transformer and a couple of relays, nothing more to it. In comparison to the complexity of the FDAC design, the extra handful of components required for the RIAA / Gain stage is insignificant, in fact the "Hard Work" is really done by the transformer.

In simple terms the "Phono stage" makes use of the ADC's Pre existing Gain blocks, but adds a selectable RIAA filter - the addition of the Transformer handles the MC Low noise gain.
Click to expand...

John this is interesting I moved to a valve stage a while ago with a sowter transformer.I was never happy with solid state stages they loose the timber of acoustic instruments and vocals for me, I have none of the traditional issues with valves that people moan about, noise, loose bass, hiss etc in fact it sounds very similar to solid state, plays tunes and has very dry deep bass.
I have a balanced input to the transformer as described by Morgan Jones in his book on valves this dropped the noise floor specifically mains hum below audability from my listening seat.I have considered a balanced valve stage for years but been to lazy to do it so interested in how this develops 1 less set of boxes would be good.
 
JohnW,

+1 for the phono stage (and associated cost),

For me 1x line and 1x phono stage ADC input is ok.

Best regards
 
JohnW said:
How many potential FDAC L3 owners are interested in a HQ internal Phono stage?
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I'm potentially interested in a phono stage.

Could the MC option be implemented as an add-on? There are some good MM cartridges around, and if it keeps the cost down more people might be interested in the basic stage.
 
I too am keen on a phono stage, currently rocking a VST Shure with Jico stylus MM, one day will see the light and try MC, so both catered for would be good, but initially MM for me.

Clerenlas said:
I'm potentially interested in a phono stage.

Could the MC option be implemented as an add-on? There are some good MM cartridges around, and if it keeps the cost down more people might be interested in the basic stage.
Click to expand...
 
If the phono input is switchable (phono / line) I could play with external phonopres plus having an input for another line source. But if we go further down that route the FDAC becomes a kind of full blown classic preamp with more and more analogue inputs. I presume that is not its nature. Anyway, I would agree with...
 
Clerenlas said:
I'm potentially interested in a phono stage.

Could the MC option be implemented as an add-on? There are some good MM cartridges around, and if it keeps the cost down more people might be interested in the basic stage.
Click to expand...

The "MC Stage" is basically a pair of rather expensive transformers - I can make these "plug in" on the PCB so owners can add the transformers at a later date.
 
TimR said:
John, I'm definitely on board for the phono stage option, that would be exactly what I'm looking for :)
Would it be a big ask to have separate MM and MC inputs to allow 2 turntables to be connected simultaneously? Probably a niche requirement, but I run one of each (I use the MM turntable for the rough second hand stuff)!
Click to expand...

Tim,

Noted, and looking into the possibilities... :)
 
Hi John,

as I noticed, everyone here is just talking about phono / full size speaker systems.
I'm into headphones only and so my special interests go to the headphone
out, wich was one of the main reasons for me to take part at the project.
The 4-pin XLR with 4W output (@ ? Ohm) is perfect so far as my favorite HPs
are Audeze LCD-3s (50 Ohm).
If my dreams come true, the FDAC amp section will be so good that
I do not need an additional headphone amp anymore. To match the flexibility to drive
different HPs in the optimal range of the digital attentuation, a selectable
gain would be a very important feature (min. High/Low better High/Medium/Low).
Are there any plans on implementing this ?

Stephan
 
JohnW said:
The FDAC analogue stage has progressed to the stage where I need to consider the ADC inputs.

Now that space and screening allows - I'm seriously considering adding the selectable MM / MC phono stage to the front end of the L3 FDAC (option at extra cost). This has been loosely discussed before - the reason I'm keen (now that its possible) is that unlike an external phone stage it will be optimised to drive the balanced ADC inputs correctly.

How many potential FDAC L3 owners are interested in a HQ internal Phono stage?
Click to expand...

I would John.
 
Peter,

I guess you don't need Analogue inputs (FDAC L2) or you only need line level inputs (FDAC L3)?
 
JohnW said:
The "MC Stage" is basically a pair of rather expensive transformers - I can make these "plug in" on the PCB so owners can add the transformers at a later date.
Click to expand...

I have no need for a phono input at the moment. Nevertheless I might consider the feature with "plug in" type transformers.

Would it be possible to make the phono input switchable between mm, mc and line level?
 
The idea forming is that the FDAC L3 will be offered in 3 versions:-

FDAC L3:-

2x Balanced line level inputs per Channel.

FDAC L3MM:-

Selectable Line level / MM stage with Flat Gain or RIAA EQ.

No MC step-up transformer fitted - but can be user upgraded at a later date by "pluging in" a pair of step-up Transformers.

FDAC L3MC:-

As FDAC L3MM but supplied with "Factory fitted" MC transformers.
 
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