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!

AmpDesigner333

DOING IT !!!!
« Reply #54 on: 9 Feb 2018, 11:32 pm »
Guess what ????

We've decided to make it happen!

Check this out (one minute):
https://youtu.be/Za7oaOKMrMo

We plan to launch soon and will have a Day 1 special.  Sign up for our newsletter so you will be notified of the details:
http://bit.ly/1G8bsxZ

Don't wait to sign up for the newsletter!  All you need is an email address.

We're also introducing our new DAC DAC 2 and Cherry ADC products!

Thanks (:

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #55 on: 25 Feb 2018, 08:36 pm »
Any thoughts ????



Nothing analog inside the DPA!
« Last Edit: 27 Feb 2018, 08:20 pm by AmpDesigner333 »

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #56 on: 27 Feb 2018, 08:19 pm »
Now available on Kickstarter for $500 off!

Take a look:
http://kck.st/2CH4sLB

There's also a more detailed description in the project text.

Thanks.

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #57 on: 4 Mar 2018, 09:35 pm »
The debate continues!

Regading an analog input on the DPA....

FOR NOW....  The ADC is external and will be called Cherry ADC  We plan for excellent performance (120dB+) and balanced inputs, probably fixed 24-bit 192kHz output.  The DPA is 100% digital this way, and only analog input performance is affected by the ADC.  Otherwise, it’s “perfect”, as in no missing bits, etc.  It is tempting to add analog inputs, but then the price will go up significantly.  However, those that bought in at the lower price on our current Kickstarter won’t be charged extra if we add features.  If we collect enough funds from this project, we’ll definitely be adding features to the DPA.  These are called "stretch goals" on Kickstarter.  A USB input and built-in ADC are definitely at the top of the list.  However, adding the ADC would erase the benefits of having no analog involved in the preamp.

Any thoughts on this?

AmpDesigner333

Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #58 on: 4 Mar 2018, 09:52 pm »
The debate continues!

Regading an analog input on the DPA....

FOR NOW....  The ADC is external and will be called Cherry ADC  We plan for excellent performance (120dB+) and balanced inputs, probably fixed 24-bit 192kHz output.  The DPA is 100% digital this way, and only analog input performance is affected by the ADC.  Otherwise, it’s “perfect”, as in no missing bits, etc.  It is tempting to add analog inputs, but then the price will go up significantly.  However, those that bought in at the lower price on our current Kickstarter won’t be charged extra if we add features.  If we collect enough funds from this project, we’ll definitely be adding features to the DPA.  These are called "stretch goals" on Kickstarter.  A USB input and built-in ADC are definitely at the top of the list.  However, adding the ADC would erase the benefits of having no analog involved in the preamp.

Any thoughts on this?
....also on the list is an optical input....

SteveMiller

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Re: Hey Tommy, any plans to make a Class D preamp?
« Reply #59 on: 6 Mar 2018, 03:02 pm »
Reading all the previous posts, it looks like there is real interest in DPA, ADC, and continued growth over at Digital Amplifier Company! Glad to hear it because over all the years in this hobby and all the gear that passed though my hands, its Tommy's designs which have finally delivered the goods!  DACDAC's, STM's, and Maraschino's have all exceeded my expectations. And due to that, I'm sure that once the feature set and product function are worked out, the forthcoming DPA will set a new standard for transparency and performance in our systems.

My .02 is this.  As I get older, and things like retirement savings and children's educations continue to sap funds from my disposable income, it becomes increasing evident that simplifying the audio chain leads to saving money, and less chance of adding deleterious connections.  An example of this would be the now additional SPDIF cables required to connect the DPA. I have found audible benefit in using a Nordost Blue Heaven to drive my DACDAC's SPDIF.  If the DPA is a completely stand alone device then it adds considerably to the price for me to add another expensive SPDIF cable.  And once I've heard that it works, I cant un-hear it...  Same goes for those who tinker with outboard power supply upgrades. Everything but the amps in one box sure makes alot of sense to me.

So, my suggestion is a modular approach.  Thinking really off the wall ideas here.  Tommy has thus far been quite an innovator in not spending wastefully on casework, and keeping a family look to the product line.  Keeping functionality in separate boxes may also have a sonic benefit, but then the cabling issues arise.  My stake would land at an option to have the DPA, DACDAC, and good power supply in one fullsize chassis.  Obviously the boards themselves would remain the same, but the option to have everything in one case would really be a mature and cost effective move. Maybe current DACDAC users could enjoy an exchange or trade up program. we'd all want to do that for the forthcoming DACDAC-2 anyway. 

Otherwise, remote & physical volume knob (encoder)..... SPDIFon RCA & BNC & Toslink would be mandatory I think.

And Tommy... I think you are on to something with the 2nd SPDIF output.  It would be great to drive a subwoofer without fear and complication of the rca's on many subs grounding out the main amplifier inputs (as we've discussed).. Would it be possible to slightly bias one SPDIF output a little higher than the other?  I'm thinking here of a user with 2 DAC's and 4 Maraschinos, but the speakers/subs being driven are different sensitivities... Being able to boost or cut one output over the other could really lend better integration of subs for advanced users!