Hey Tommy, any plans to make a Class D preamp?

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AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #40 on: 29 Dec 2017, 04:39 am »
Sounds good to me...Will the preamp be able to be used with other dacs? Upsample? Sample rates?
Thinking selectable 96/24 or 192/24 output.  Auto-up-sample.  Compatible with any DAC with a coax SPDIF input.  Does this sound ok to you?  Thanks for your kind post.


rodge827

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #41 on: 29 Dec 2017, 06:49 am »
Thinking selectable 96/24 or 192/24 output.  Auto-up-sample.  Compatible with any DAC with a coax SPDIF input.  Does this sound ok to you?  Thanks for your kind post.

Yes it does sound OK to me  :thumb:

Thanks for answering my inquiry  8)

Jonathon Janusz

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Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #42 on: 29 Dec 2017, 02:31 pm »
OK, so here's the product as I see it, the Digital Amp Co Digital Preamp (DPA)....  4 Digital Inputs, including USB, optical SPDIF, 2 x Coax SPDIF, and 2 stereo Analog Inputs (single ended).  The output is coax SPDIF (to drive the DAC DAC).  It will feature a volume control with learning remote.  How does THAT sound?


As a source switcher with volume control for a customer to make a complete Digital Amp Co. front end system (minus source), great! 

As a general use preamp to get people IN to the Digital Amp Co. ecosystem or as a competitive product to other preamps on the market, not so much.  As envisioned, you are taking for granted that a customer has an (unknown) DAC capable of driving (unknown) amplifiers directly, and also that their (unknown) DAC doesn't already include preamp functionality/volume control (a seemingly increasingly common feature).

If your intent is a general-use preamp product, I would think you would need to add analog output functionality (fully balanced, both input and output actually, if you were to stay consistent with what seems to be Digital Amp Co.'s overarching design philosophy).

As presented, and for the intended purpose, it really still makes me wonder why not just go the rest of the way and integrate the final DAC into the box (making it a "modern" DAC/pre), even if the SPDIF output is retained.  If the idea ultimately is to fully vertically integrate a Digital Amp Co. solution, how much reason is there not to just build a complete integrated amplifier with digital inputs (basically a more robust/fully featured STM)?  This continuing down the rabbit hole of integration is likely irrelevant presuming the ultimate goal of the device is to complete "partial" Digital Amp Co. systems already in the wild, rather than promote existing customers replace/upgrade to the newest, latest, greatest product.

I guess the short is it  depends on exactly how many of these you want to sell and who the target buyer is.  I don't know if that was the answer you were looking for, but that's my humble opinion (for as little as that is worth, as I really don't have any vested interest in the solution).

AKLegal

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #43 on: 29 Dec 2017, 02:34 pm »
A couple of questions:

Digital gain.  My dac has 4V output from xlr.  If say I used my media server to control the volume I can access all of those 4V which is more than enough to drive most amps.  So when you are talking about digital gain are you saying that the preamp will reduce volume (from full output) without tossing away bits?  Since there wouldn't be any point in adding information to the signal to increase volume over the source's maximum output.

I am assuming there will be a way to completely bypass the preamp's upsampling capability.  There are quite of few of us that are either using NOS dacs by choice (not me), dacs with proprietary upsampling, or folks upsampling using computer software (like SoX resampling).

The ultimate question for buyers would be "are completely digital volume controls better than analog?" If yours is then the target consumer is everyone who currently uses an analog preamp with either a computer/DAC combo or a CD transport/DAC combo.  Further integration into a DAC/Preamp combo would make it hard to distinguish your preamp from the Auralics (media servers and dacs), and Wyred 4 Sounds (DACs) of the world.

Also, thanks for the consideration of HT bypass.  I'm looking forward to see what you come up with.
« Last Edit: 29 Dec 2017, 03:36 pm by AKLegal »

Jonathon Janusz

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Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #44 on: 29 Dec 2017, 02:48 pm »
Interesting!  I hadn't considered someone looking specifically for a digital volume control solution (with impedance buffering?) to replace/"upgrade" from an analog preamp solution.

I am a fan of the NOS solution in general, which makes me pause for your question about the preamps upsampler, which I think (wonder?) is an unavoidable consequence of implementing a high quality digital volume solution?

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #45 on: 29 Dec 2017, 08:13 pm »
As a source switcher with volume control for a customer to make a complete Digital Amp Co. front end system (minus source), great! 

As a general use preamp to get people IN to the Digital Amp Co. ecosystem or as a competitive product to other preamps on the market, not so much.  As envisioned, you are taking for granted that a customer has an (unknown) DAC capable of driving (unknown) amplifiers directly, and also that their (unknown) DAC doesn't already include preamp functionality/volume control (a seemingly increasingly common feature).

If your intent is a general-use preamp product, I would think you would need to add analog output functionality (fully balanced, both input and output actually, if you were to stay consistent with what seems to be Digital Amp Co.'s overarching design philosophy).

As presented, and for the intended purpose, it really still makes me wonder why not just go the rest of the way and integrate the final DAC into the box (making it a "modern" DAC/pre), even if the SPDIF output is retained.  If the idea ultimately is to fully vertically integrate a Digital Amp Co. solution, how much reason is there not to just build a complete integrated amplifier with digital inputs (basically a more robust/fully featured STM)?  This continuing down the rabbit hole of integration is likely irrelevant presuming the ultimate goal of the device is to complete "partial" Digital Amp Co. systems already in the wild, rather than promote existing customers replace/upgrade to the newest, latest, greatest product.

I guess the short is it  depends on exactly how many of these you want to sell and who the target buyer is.  I don't know if that was the answer you were looking for, but that's my humble opinion (for as little as that is worth, as I really don't have any vested interest in the solution).
This is morphing into an integrate-or-not discussion, and you bring up several good points!

We can look at it another way....  We're currently making DACs and USB converters.  We could add the digital preamp and an EXTERNAL ADC as two new products.  This allows the preamp to be a completely digital product.

The ADC can fit into the slim case we use for the Cherry USB (see below).  I'm leaning toward single ended inputs for that because it's more than adequate for phono or home theater pass through.  The STM has the advantage of a front jack to hook up Bluetooth or mobile devices, although the performance is way better than necessary for such devices.

Thanks as always for your great posts!



Jonathon Janusz

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Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #46 on: 29 Dec 2017, 09:26 pm »
We can look at it another way....  We're currently making DACs and USB converters.  We could add the digital preamp and an EXTERNAL ADC as two new products.  This allows the preamp to be a completely digital product.

The ADC can fit into the slim case we use for the Cherry USB (see below).  I'm leaning toward single ended inputs for that because it's more than adequate for phono or home theater pass through.

That would solve the problem of folks looking for a preamp solution for existing analog devices (assuming you would include enough digital inputs of the appropriate connection type for the ADC converter to make enough room for enough analog inputs to satisfy most customers; three seems to be the baseline industry trend here). but still means ultimately the preamp would need to either use a DAC DAC for final output to (uknown) amps to be a general use preamp product, or another (unknown) DAC that could also do it (and again that couldn't just do the preamp/volume functions on its own anyway).

I'm not sure I would limit such a device as being single ended only (or also develop another one that was balanced), because (other than what seems to be DAC's position on the advantages of a fully balanced signal path) I'm fairly confident that the last thing an audiophile would accept hearing is that something is just "good enough", no matter the circumstance, when trying to improve their system(s).

If the thought is to separate/go modular in design approach rather than integrate (for marketability/wider applicability reasons than potential performance gains from more tightly integrating), why not go even further the other direction and make a simple single digital input - single digital output volume control unit, that one would then add on a chain of whatever modules are required behind it (digital or analog, single ended or balanced, input switchers, single ended or balanced analog output units, ADC units, etc.)? 

Because the case sizes on many Digital Amp Co. products are relatively small, space likely isn't much of an issue, but this approach would (might?) add on a larger pile of interconnects, power supplies, power cords, etc. than the alternative more integrated solutions.  Like most everything else in this hobby, some would see this as a problem, others a feature.

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #47 on: 29 Dec 2017, 11:49 pm »
That would solve the problem of folks looking for a preamp solution for existing analog devices (assuming you would include enough digital inputs of the appropriate connection type for the ADC converter to make enough room for enough analog inputs to satisfy most customers; three seems to be the baseline industry trend here). but still means ultimately the preamp would need to either use a DAC DAC for final output to (uknown) amps to be a general use preamp product, or another (unknown) DAC that could also do it (and again that couldn't just do the preamp/volume functions on its own anyway).

I'm not sure I would limit such a device as being single ended only (or also develop another one that was balanced), because (other than what seems to be DAC's position on the advantages of a fully balanced signal path) I'm fairly confident that the last thing an audiophile would accept hearing is that something is just "good enough", no matter the circumstance, when trying to improve their system(s).

If the thought is to separate/go modular in design approach rather than integrate (for marketability/wider applicability reasons than potential performance gains from more tightly integrating), why not go even further the other direction and make a simple single digital input - single digital output volume control unit, that one would then add on a chain of whatever modules are required behind it (digital or analog, single ended or balanced, input switchers, single ended or balanced analog output units, ADC units, etc.)? 

Because the case sizes on many Digital Amp Co. products are relatively small, space likely isn't much of an issue, but this approach would (might?) add on a larger pile of interconnects, power supplies, power cords, etc. than the alternative more integrated solutions.  Like most everything else in this hobby, some would see this as a problem, others a feature.
Interesting concept!  So, where do we draw the line on integration?  Originally, we were thinking "everything but the amp".  Now we're talking about pretty much the opposite.  Would most customers want a "DAC driver" (various analog and digital inputs) or a digital selector/volume control?

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #48 on: 30 Dec 2017, 12:01 am »
A couple of questions:

Digital gain.  My dac has 4V output from xlr.  If say I used my media server to control the volume I can access all of those 4V which is more than enough to drive most amps.  So when you are talking about digital gain are you saying that the preamp will reduce volume (from full output) without tossing away bits?  Since there wouldn't be any point in adding information to the signal to increase volume over the source's maximum output.

I am assuming there will be a way to completely bypass the preamp's upsampling capability.  There are quite of few of us that are either using NOS dacs by choice (not me), dacs with proprietary upsampling, or folks upsampling using computer software (like SoX resampling).

The ultimate question for buyers would be "are completely digital volume controls better than analog?" If yours is then the target consumer is everyone who currently uses an analog preamp with either a computer/DAC combo or a CD transport/DAC combo.  Further integration into a DAC/Preamp combo would make it hard to distinguish your preamp from the Auralics (media servers and dacs), and Wyred 4 Sounds (DACs) of the world.

Also, thanks for the consideration of HT bypass.  I'm looking forward to see what you come up with.
Technically, with digital gain, you're losing one bit every 6dB of "boost", but at 32-bits (internal processing), this is negligible, and more than 12dB or so isn't very useful, so that may be the limit.

With a really good DAC, digital volume out performs analog.  I'm sure there are those that will argue with me, but analog volume controls add noise and distortion (regardless of the volume setting).  With digital volume, attenuation of more than 50dB (!) still retains 16-bit resolution (assumes 24-bit output to the DAC)!  The math for this isn't that complicated, and with digital, it all comes down to math --- not PCB layout, wires, power supplies, etc.


Jonathon Janusz

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Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #49 on: 30 Dec 2017, 01:50 am »
Interesting concept!  So, where do we draw the line on integration?  Originally, we were thinking "everything but the amp".  Now we're talking about pretty much the opposite.  Would most customers want a "DAC driver" (various analog and digital inputs) or a digital selector/volume control?

I wish I had the level of concrete market research data to give a good answer, but if this thread is any indication, it looks like the folks with interest are about split 50-50 between a quality analog preamp (no digital functionality for anything, really) and a digital selector/vc with maybe a little analog functionality on the side.  As you've had good success with kickstarters before, it might not be a bad idea to rough out your dream on paper, throw it out there, and see what sticks.  Whichever widget gets backed = the market has spoken, and you're not out much more than a little time to figure it out.

Technically, with digital gain, you're losing one bit every 6dB of "boost", but at 32-bits (internal processing), this is negligible, and more than 12dB or so isn't very useful, so that may be the limit.

This suggests that the NOS proponent camp need not apply to a digital volume solution, as it sounds like processing the source data is just the cost of doing business?

Quote
... and with digital, it all comes down to math --- not PCB layout, wires, power supplies, etc.

I'd be a little cautious throwing this one around, unless you want to maybe fork this idea off into another thread for discussion, rather than derail this "preamp ideas" thread.  This sounds a lot like a "bits are bits" position regarding digital, which might open a whole different can of debate that has little to do with what kind of feature set your customers would like to see in a preamp/digital volume control product.

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #50 on: 30 Dec 2017, 09:11 pm »
This may need to be a separate thread, but we've been asked to consider the following products, and going along with Jon's insights, the preamp is divided into two products:
1. Analog Preamp
2. Digital Preamp
3. Headphone amp
4. Maraschino 2 - MONOs with 60V 1kW power supply built-in

Thoughts on these potential Kickstarter funded projects?

Early B.

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #51 on: 30 Dec 2017, 10:40 pm »
I like it!  Add me to the analog preamp list.

For the Maraschino 2's -- is the built-in power supply mainly for convenience or will it be a re-design with sonic improvements?   

GregC

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #52 on: 31 Dec 2017, 12:42 am »
So no hope for a HT bypass option? 

Also, a spdif output? 

 I'm really enjoying a pair of the in line Masachino's I picked up this month.  They are really amazing amps.

Glad you are enjoying the amps I thought you would. :)

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #53 on: 31 Dec 2017, 04:18 am »
I like it!  Add me to the analog preamp list.

For the Maraschino 2's -- is the built-in power supply mainly for convenience or will it be a re-design with sonic improvements?
We might be able to modify the design to include some of the sonic advances we used in the MEGAschino!