MDAC First Listen (part 00011110)
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JohnW
pfm member
Yes very much so, an external attenuator increase the output impedance - A few like myself have noticed that this impacts the Bass performance.
By designing the "attenuator" as part of the Analogue Gain stage, the extra -20dB is used to increase the Feedback gain, this further lowers distortion, increases SNR & reduces output impedance - all positives.
Adding attenuators external, just converts the unwanted signal into heat, while at the same time increasing output impedance and Noise.
Yes, inserting headphones would enable a new DSP Profile - you have the option of crossfeed or Tone controls / EQ if desired - or just totally bypassed
JohnW
pfm member
Just wish to stress that the MDAC2 will be offered in two versions:-
1. The Basic unit
2. MDAC2+ with DSP, Bluetooth & -20dB Analogue attenuation
The DSP option should not just be considered as "Room correction" which is not my cup of tea. But that said I have a negative opinion of "room correction" due to my own personal prejudice that the signal is no longer "Pure", but what's the worst 'poison' - nasty room standing waves or a stab at simple EQ... I'm open to trying room correction as its stupid to live in fear of something you have never tried - certainly not something that can be bypassed without any lasting "ill effect"....
Its like the fear of tone controls - just because they don't feel "pure" that somehow I'm cheating my HiFi system - its like lifting the Bass because you enjoy your system more, but feeling ashamed for doing it!
At the end of the day - plonking a speaker into any room and you will have far from flat / smooth response, so its a no less of an evil to try and correct for some of the more nasty resonate peaks.
Having never tried room correction in my own system I have no idea if its something I'll use - but I'm going to try so that I can either say "Yes" simple EQ does indeed work well or no tried it, its just a cheap band aid which has no place in HiFi... But without trying a system I'd like to believe is "well implemented" such as the 56bits mathematical precession and only adding gentle correction, I'd be prejudiced without reason.
With the DSP we can also add very gentle Tone controls.... Headphone crossfeed and potentially more exciting for my "purist" HiFi nature are more advanced digital filters that could eliminate pre-ringing etc... Who knows what we will develop in the future that can make use of the on-board DSP.
I might not use the DSP on the first day, but I'm happy to know I have it on tap for future developments, especially as it does not negatively impact the performance when not used.
My car has a Twin Turbo 12 cylinder engine, do I ever use that power, I doubt it - but it gives me confidence that its available in case I ever do.
What I hope not to read in the future on the forum is owners start to complain once we release software for the DSP units which cannot be tried on the MDAC2 Basic version - such as when we start investigating more complex filter structures that are easier to implement on the DSP in software rather then designing new "Hardware" blocks in the FPGA.
It might be possible in the longer term based on the experiences gained with the DSP software implementation to then design a "hardware" FPGA block (so the Filter / feature could be installed on the basic units) - but its speculation without foresight at this time as somethings are just more practical / possible with a DSP engine - I don't wish any ill will / hard feelings from any of our MDAC2 owners
No East / West divide between the Have's and Have not's please
JohnW
pfm member
I'd like to rise an important point that DSP on the PC and DSP performed in the MDAC is not the same, as any DSP on the PC has to be truncated to 24bits to be sent to the external DAC, while DSP operations performed in the MDAC can be sent to the Modulator in full 56bits precession - our past work on even simple FPGA based Digital filter has demonstrated that any increased in data path width is beneficial to SQ.
Its one of the reasons that gives me hope that it might be useful - not just a cheap effects processor or some such...
We would also combine the response of any EQ with the Digital filter section so simplifying the digital signal path.
Akasha
pfm Member
I'm in for DSP even though my listening room is "optimized" with diffusers, absorbers, angled walls etc. and the DSPs I've tried even with gently adjustment lacks some 3D in depth clarity,
I'm sure It can be done right with mostly benefits.
What I need the most is gently "tone controls" or tilt of frequency band from the remote, I have all kinds of great music from the past 60 years and with 108db sensitive speakers the frequency balance of recorded music differs in all directions from a unbearable rich bass with "distant" treble to: "who the hell disconnected the bass system"
some argue "its not HiFi" to use tone controls, but neither are the "small 86db vented monitors" many producers uses when they f**k up good music these days. For me the music comes first
only 20-30 percent of normal tracks I will say is neutral ( not even speaking of these days heavy compressed remastered tracks made for car environment replay)
just a few half db "clean" tilt or adjustment from the remote will really do it for me, worth much more than 100GBP
I'm sure It can be done right with mostly benefits.
What I need the most is gently "tone controls" or tilt of frequency band from the remote, I have all kinds of great music from the past 60 years and with 108db sensitive speakers the frequency balance of recorded music differs in all directions from a unbearable rich bass with "distant" treble to: "who the hell disconnected the bass system"
some argue "its not HiFi" to use tone controls, but neither are the "small 86db vented monitors" many producers uses when they f**k up good music these days. For me the music comes first
only 20-30 percent of normal tracks I will say is neutral ( not even speaking of these days heavy compressed remastered tracks made for car environment replay)
just a few half db "clean" tilt or adjustment from the remote will really do it for me, worth much more than 100GBP
It might be only me...
I would like to remind that this MDAC2 development project is made possible only because group of individuals (excludes those who will "get MDAC2 PCB at cost") has decided to financing it. At first place this group of individuals have committed to finance the original development plan with predefined feature set, cost estimation and timetable.
I would like to expect that any new features or changes to predefined feature set that will cause changes to estimated costs and/or timetable will be communicated and approved via email (email addresses were collected with payments) or other way by this same (financing) group of individuals before any such changes are decided to implement in part of the original project.
As an example if majority of individuals in financing group approves proposed changes to original feature set it will come an optional feature and all additional costs of the added feature will be paid by those who will order it separately. Changes to timetable is also approved at same time. If proposed new feature is not supported by majority it will not be implemented in this project.
The sad thing is that at the moment public forum is used as an one way announcement channel and any opposite feedback from individuals in real financing group is ignored.
At the same time original project timetable continue to slipping.
JohnW
pfm member
Thats the point, most small box speakers are no more or less HiFi then simple tone controls - so why be prejudiced against using tone controls or simple EQ (which I'm very much as guilty of this prejudice) when the almost all speakers are far from prefect - not to mention the mastering!
I'd be happy to be proved wrong - and that EQ / Tone controls can be implemented beneficially, to that end 56Bit DSP processing seems like a good place to start...
moosemeat
pfm Member
Just wish to stress that the MDAC2 will be offered in two versions:-
1. The Basic unit
2. MDAC2+ with DSP, Bluetooth & -20dB Analogue attenuation
The DSP option should not just be considered as "Room correction" which is not my cup of tea. But that said I have a negative opinion of "room correction" due to my own personal prejudice that the signal is no longer "Pure", but what's the worst 'poison' - nasty room standing waves or a stab at simple EQ... I'm open to trying room correction as its stupid to live in fear of something you have never tried - certainly not something that can be bypassed without any lasting "ill effect"....
Its like the fear of tone controls - just because they don't feel "pure" that somehow I'm cheating my HiFi system - its like lifting the Bass because you enjoy your system more, but feeling ashamed for doing it!
At the end of the day - plonking a speaker into any room and you will have far from flat / smooth response, so its a no less of an evil to try and correct for some of the more nasty resonate peaks.
Having never tried room correction in my own system I have no idea if its something I'll use - but I'm going to try so that I can either say "Yes" simple EQ does indeed work well or no tried it, its just a cheap band aid which has no place in HiFi... But without trying a system I'd like to believe is "well implemented" such as the 56bits mathematical precession and only adding gentle correction, I'd be prejudiced without reason.
With the DSP we can also add very gentle Tone controls.... Headphone crossfeed and potentially more exciting for my "purist" HiFi nature are more advanced digital filters that could eliminate pre-ringing etc... Who knows what we will develop in the future that can make use of the on-board DSP.
I might not use the DSP on the first day, but I'm happy to know I have it on tap for future developments, especially as it does not negatively impact the performance when not used.
My car has a Twin Turbo 12 cylinder engine, do I ever use that power, I doubt it - but it gives me confidence that its available in case I ever do.
What I hope not to read in the future on the forum is owners start to complain once we release software for the DSP units which cannot be tried on the MDAC2 Basic version - such as when we start investigating more complex filter structures that are easier to implement on the DSP in software rather then designing new "Hardware" blocks in the FPGA.
It might be possible in the longer term based on the experiences gained with the DSP software implementation to then design a "hardware" FPGA block (so the Filter / feature could be installed on the basic units) - but its speculation without foresight at this time as somethings are just more practical / possible with a DSP engine - I don't wish any ill will / hard feelings from any of our MDAC2 owners
No East / West divide between the Have's and Have not's please
John,
Thank you for this clarification. I must admit, I was playing catch-up on this thread when I posted my comment and probably jumped in a little prematurely. I'm a 'horses for courses' sort of guy and was concerned that MDAC2 might become an 'all things to all people' sort of a gadget which could result in it not doing anything particularly well.
I have to agree with your don't knock it 'til you've tried it philosophy, so I'll give DSP a crack.
Cheers,
Bruce
JohnW
pfm member
Timow,
I understand your concerns.
But again I like to stress that the DSP / Bluetooth DOES NOT DELAY THE PROJECT - Dominik is handling the design of the Digital PCB - it will be completed before the final version of the Analogue board that I'm designing.
The additional Analogue attenuator sections are on the Analogue board so will have a slight impact on the project timeline - I'm about to reach that section of the design within this week - but the good news is I'm not having to rip-up the design to add the attenuators - so if anyone is unhappy because of the slight extra delay of adding the attenuators then they can Email me expressing there wish to pull-out of the project because of this additional slight delay and I'll understand - I'll happily return there pledged funds, I'll be VERY saddened to see anyone opted out because I truly believe the MDAC2 design will be better for the additions - as with any complex project there are always slight digressions from the original plan when things are found that can be improved or where not given there due consideration at the start of the project.
I'm trying to balance commonly requested features, and the Analogue attenuation is probably the most common "extra" requested - with some form of EQ / DSP as the second,
I added Bluetooth option because it cost so little, will not delay the project in anyway, and I'm sure nobody gave it any consideration unaware it was possible.
The Bluetooth is not about HiFi is just a connivance feature, that can be added for very little effort or expense and does not impact the SQ when not powered.
I cannot make 100% of the people 100% happy - I can however refund your pledge if your unhappy with this turn of events - but it will not stop me designing the very best product I can offer - I truly don't want to loose anyone in the process.
As this is a "Public project" I feel its better to have any proposed changes discussed here on the forum in public - not via private emails.
For those who feel strongly against the changes - there will still be the "Original design offered" - and I'll pledge to work even longer hours so that the addition of the Analogue attenuators does not impact the end design time of the Analogue board with any significance.
JohnW
pfm member
Bruce,
No problem - I just want to clarify that the DSP is not only intented for Room correction / EQ that may or may not work well - but for other tasks such as advanced digital filtering, Crossfeed, compressor for late night film sessions etc - who knows what we can play with later - just as with the MDAC software updates we well expanded the MDAC2's feature set - some might be worthwhile - others just experimenting, but the idea is to keep the MDAC2 ahead of the curve and "interesting", while NEVER compromising its basic audio performance.
Fundamentally - I'm designing the MDAC2 to be the best sounding DAC I can (within the limits of the MDAC chassis / scope of the project) - rest assured that if I felt the DSP option would take away from its basic SQ I'd NEVER propose it.
JohnW
pfm member
I don't think its far to say that "real financing group is ignored" - there are only about 30 "at cost" upgraded units - while over 100 from pledged owners
Its my bad if I've not stressed clearly enough that the "original design" is still being offered, with the more advance version being offered at an additional sum - this extra sum paying for the extra development work as so not to burden those who have no interest in it.
The extra DSP / BT (on the Digital PCB) is being designed in parallel with Analogue stage and well not impact the release date of the basic version - the Analogue board is the real design battle.
And to satisfy YOUR concerns I'll work extra time to insure the addition of the Analogue attenuators that I have been constantly requested to add does not impact the release date of the Analogue board. By deciding to add the analogue attenuation I'm trying to satisfy the "majority" demand, or atleast those who are most vocal
- trust me that its so much it easier for me not to bother and just keep the design simple, the extra design additions only serve to make Dominik's and my task as the designers harder, but I have always worked by the ethos that the "best" is never achieved without pushing the design goals - and pushing myself to the edge!I'm sorry you feel the way you do - and now maybe you can understand why I can never work and never will work within a company structure again.
It might not only be you...
But no, that's not what you've joined
Like it or not, you've joined an 'act of faith' in a particular design team. And I think that has been clear throughout (it's been clear to me). I'm not sure where you thought there was some sort of formally defined review process in this.
The original conceptual outline spec is just that, a concept and an outline. It's not a 'predefined feature set' it's simply a starting point for whatever will follow.
So there is no controlling 'finance group'. Heaven forbid - "who votes for green and who votes for purple? Carried - orange it is". If you want a formal approval process you'll have to start your own company and run your own development projects. This design process is neither.
I don't see responses being ignored, far from it. Possibly John is a little too willing to listen to responses
. I do see that whatever response is received and however it is interpreted it can never please all of the people all of the time.Far from the the use of this (or any other) forum being a cause for sadness, it provides an insight into what is going on in a particular design process and an opportunity to communicate with the designer that is seldom seen.
Based on any prior evidence the timetable was always destined to slip, so no surprise there. But it's always interesting to see which goodies have been added as a result of the additional time invested.
Sit back and enjoy the ride. This is up to John. We're all spectators. John's designs and his design process have always been entertaining and simply require a little patience
JohnW
pfm member
Chris thank you for your understanding and support
While I worked with Audiolab (China) I received exactly the same (negative) response - they where only too happy to reap the awards and publishing full page spreads proudly highlighting all the 5 star reviews and awards Dominik and my designs had won - but not once did they appreciate the development path required to create such a product... They made my life truly hell, quite possibly the worst 3 years of my working career.
Once the products where finally released it was a very odd atmosphere as each 5 start review and Award just made them loose more "Face" as each just served to prove that while I work in an unconventional manor the end results spoke for themselves. Not once did they congratulate me - despite the awards being such an important event for Audiolab that up until that point had all but disappeared from the HiFi public's radar. It got kind of embarrassing as they would try to avoid me rather then having to say anything.
It was doubly hard as the Chinese culture follows a very rigid hierarchy - you obey your superior no matter how uninformed he might be... Yep, that was just a sure recipe for disaster for me
I don't set out to be difficult to work with - but I have singe track goal of designing the best and I follow the path that my instincts as a designer tell me to achieve that goal.
I believe that after all I've learnt over the past 3 years of "peaceful" development time I've had here in Czech, that the MDAC2 will be very special indeed.......... once its released that is
While I worked with Audiolab (China) I received exactly the same (negative) response - they where only too happy to reap the awards and publishing full page spreads proudly highlighting all the 5 star reviews and awards Dominik and my designs had won - but not once did they appreciate the development path required to create such a product... They made my life truly hell, quite possibly the worst 3 years of my working career.
Once the products where finally released it was a very odd atmosphere as each 5 start review and Award just made them loose more "Face" as each just served to prove that while I work in an unconventional manor the end results spoke for themselves. Not once did they congratulate me - despite the awards being such an important event for Audiolab that up until that point had all but disappeared from the HiFi public's radar. It got kind of embarrassing as they would try to avoid me rather then having to say anything.
It was doubly hard as the Chinese culture follows a very rigid hierarchy - you obey your superior no matter how uninformed he might be... Yep, that was just a sure recipe for disaster for me
I don't set out to be difficult to work with - but I have singe track goal of designing the best and I follow the path that my instincts as a designer tell me to achieve that goal.
I believe that after all I've learnt over the past 3 years of "peaceful" development time I've had here in Czech, that the MDAC2 will be very special indeed.......... once its released that is
delange
pfm Member
John, I haven't been closely following this thread lately so forgive me if this has been asked before: will the analogue attenuator have a motor control / I mean, will it be possible to control the analogue attenuator by means of a remote control?
iansr
pfm Member
You got that bang on Chris. It would be totally naive to expect John to know at the outset exactly how our expectations / his thinking might evolve as the project progresses. In the world of hi fi if you can't put your faith in someone like John then we might as well all give up.It might not only be you...
But no, that's not what you've joined
Like it or not, you've joined an 'act of faith' in a particular design team. And I think that has been clear throughout (it's been clear to me). I'm not sure where you thought there was some sort of formally defined review process in this.
The original conceptual outline spec is just that, a concept and an outline. It's not a 'predefined feature set' it's simply a starting point for whatever will follow.
So there is no controlling 'finance group'. Heaven forbid - "who votes for green and who votes for purple? Carried - orange it is". If you want a formal approval process you'll have to start your own company and run your own development projects. This design process is neither.
I don't see responses being ignored, far from it. Possibly John is a little too willing to listen to responses
Far from the the use of this (or any other) forum being a cause for sadness, it provides an insight into what is going on in a particular design process and an opportunity to communicate with the designer that is seldom seen.
Based on any prior evidence the timetable was always destined to slip, so no surprise there. But it's always interesting to see which goodies have been added as a result of the additional time invested.
Sit back and enjoy the ride. This is up to John. We're all spectators. John's designs and his design process have always been entertaining and simply require a little patience
John: I have complete confidence in your decisions and I'm with you all the way.
JohnW
pfm member
Delange,
The Analogue attenuator is just a single step -20dB attenuator which is automatically selected when the MDAC's listening level is set below -20dB.
My normal listening level is around -25 dB, which would mean that with the -20dB analogue attenuation the MDAC is only applying 5dB of Digital domain attenuation.
The Analogue attenuator is just a single step -20dB attenuator which is automatically selected when the MDAC's listening level is set below -20dB.
My normal listening level is around -25 dB, which would mean that with the -20dB analogue attenuation the MDAC is only applying 5dB of Digital domain attenuation.
JohnW
pfm member
giannitom
pfm Member
As i understand, John is trying to get the best from the analog stage while Dominik is doing the same for the digital stage. This was the initial goal of the project and beyond all the technical details and particular features it seems to me that it is not changed. Indeed, precisely to meet this goal it is understandable that details and specs need to be reviewed from time to time.
Keep up the good work John and Dominik!
Keep up the good work John and Dominik!
I'm 100% sold on the DSP version now.
Would it be any help if we added our preference for DSP or non-DSP against our name in the pledge list to give you an idea of numbers? I've just updated mine anyway.
Sit back and enjoy the ride. This is up to John. We're all spectators. John's designs and his design process have always been entertaining and simply require a little patience
Exactly and it has been an interesting journey. I am 100% satisfied with the feature set.
So John and Dominic you also have my support!
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