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Audio/Video Gear and Systems => Owner's Circles => Digital Amplifier Company Owners => Topic started by: Wind Chaser on 11 Dec 2017, 11:55 pm

Title: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 11 Dec 2017, 11:55 pm
I'm so impressed with your little amps I go to thinking, why not apply this technology upstream?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: smargo on 12 Dec 2017, 04:38 am
 
I'm so impressed with your little amps I go to thinking, why not apply this technology upstream?

what preamp are you using currently - curious?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 12 Dec 2017, 06:09 am
what preamp are you using currently - curious?

Nuprime DAC-10.  One of the reasons I chose this was because it integrates the DAC with the preamp.  However given how incredible the Maraschinos sound, why not incorporate that same technology in a preamp DAC combo?  I bet it has the potential to sound much better any tube counterpart.   :green:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 13 Dec 2017, 12:05 am
Nuprime DAC-10.  One of the reasons I chose this was because it integrates the DAC with the preamp.  However given how incredible the Maraschinos sound, why not incorporate that same technology in a preamp DAC combo?  I bet it has the potential to sound much better any tube counterpart.   :green:
Here is an elegant, short signal path, audio performance based DAC.  There are two versions, High-Spec (HS) and Tube-Like (TL).  HS performance is 124dB, 0.0004% THD.  The TL provides 120dB, the shortest signal path output stage, and is the only "tube-like" output stage emulation on the market.  Info on our web site:
http://www.cherryamp.com/dac-dac-d-to-a-convertor

Some more info from users of these DACs here on Audio Circle:
http://www.audiocircle.com/index.php?topic=138311.0

(http://www.audiocircle.com/image.php?id=172681)


(http://www.audiocircle.com/image.php?id=172682)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 13 Dec 2017, 12:54 am
I'm so impressed with your little amps I go to thinking, why not apply this technology upstream?
Under consideration!

That reminds me....  Thought I should mention our popular STM (Stereo Maraschino).  It provides two inputs and a volume control.

Some STM info:
http://www.cherryamp.com/stereo-maraschino-stm

....and here:
http://v2.stereotimes.com/post/stereo-maraschino-amplifier

....and it won the Stereo Times Most Wanted Component Award in 2016:
http://v2.stereotimes.com/page/most-wanted-2016

(http://www.audiocircle.com/image.php?id=172679)

(http://www.audiocircle.com/image.php?id=172680)

Thanks for the compliment.

-Tommy O
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: dburna on 13 Dec 2017, 01:03 am
....and here:
http://www.stereotimes.com/post/digital-amplifier-co.-maraschino-cherry-amplifier

....and it won the Stereo Times Most Wanted Component Award in 2016:
http://www.stereotimes.com/page/most-wanted-2016


Tommy, I think Stereo Times has updated their web site.  I believe their address is now www.v2.stereotimes.com.  At least that's what works for me.  When I try to click on the above links directly I get an unresolved address.

Regards,  -dB
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 13 Dec 2017, 02:22 am
Tommy, I think Stereo Times has updated their web site.  I believe their address is now www.v2.stereotimes.com.  At least that's what works for me.  When I try to click on the above links directly I get an unresolved address.

Regards,  -dB
Fixed the links.  Thanks for the head's up!
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: mfsoa on 14 Dec 2017, 01:10 am
That Stereo Maraschino is hella fun. If you only need one input it's just superb.

I've lived with one for a few months with a 60V supply. I think Tommy's got a linear supply available now.

My friend  uses one in his Manhatten apt, fed by an Oppo 205 and powering Von Schweickert VR4JRs. Sounds great.

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 14 Dec 2017, 05:30 pm
Ok, let's make some decisions about this product!  The pieces are in place.  We can do analog or digital volume, whatever number of inputs, analog and/or digital, and outputs in both RCA and XLR.  This will be a 2-channel thing, at least the first one.

Please help out by answering these quick questions....

1. How many inputs?
2. What type of inputs?
3. Ideal price point?  Please don't say "zero"  8)
4. Digital or analog volume?

That should be enough to get us started.  Thanks for participating.

-Tommy O
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: opnly bafld on 14 Dec 2017, 05:46 pm
Remote control?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 14 Dec 2017, 06:05 pm
Ok, let's make some decisions about this product!

Are we talking strictly about a line stage / control center or a DAC preamp combo?

And a very definite big yes to a remote, but something of quality, not a disposable piece of plastic.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: poseidonsvoice on 14 Dec 2017, 06:35 pm
And a very definite big yes to a remote, but something of quality, not a disposable piece of plastic.

http://www.bentaudio.com/index2.html

Best,
Anand.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: smargo on 14 Dec 2017, 08:33 pm
Ok, let's make some decisions about this product!  The pieces are in place.  We can do analog or digital volume, whatever number of inputs, analog and/or digital, and outputs in both RCA and XLR.  This will be a 2-channel thing, at least the first one.

Please help out by answering these quick questions....

1. How many inputs?
2. What type of inputs?
3. Ideal price point?  Please don't say "zero"  8)
4. Digital or analog volume?

That should be enough to get us started.  Thanks for participating.

-Tommy O


1. 5 inputs and 1 subwoofer out

2. 2 balanced and 5 rca's

3. $700 to $1000

4. digital volume control

5. remote (a must)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 15 Dec 2017, 04:21 am

1. 5 inputs and 1 subwoofer out

2. 2 balanced and 5 rca's

3. $700 to $1000

4. digital volume control

5. remote (a must)

Thanks for your answers!
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AKLegal on 15 Dec 2017, 04:39 am
Home theater pass through or at least a custom option for one.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz on 15 Dec 2017, 05:23 am
Would it be the right idea to build in a DAC DAC and USB/SPDIF digital input options?  The biggest question these days about bundling a DAC into a preamp seems to be the speed at which DACs are coming out and people change them up.  If the system isn't built modularly such that a DAC can be swapped out easily, even a top-shelf DAC today built in can end up a waste of back panel connector space and unused with tomorrow's newest wonder DAC.  My opinion, as little as it matters, is with the quality to value ratio the DAC DAC and the USB converter have, I think packing them into the case (along with the associated shortening/optimizing of the signal paths even further than today's separate boxed solutions) is a good idea, even if at some point later a customer relegates the DAC section to being a "backup DAC" to whatever newest external DAC gets connected to the preamp.

With digital input capability, two or three analog inputs would probably be enough.

Would sound quality suffer if all the analog inputs/outputs were balanced, with the option of adding RCA-XLR adapters rather than SE/RCA I/O - this seems to be the standard setup for your existing gear?

I think having three sets of outputs standard would be a differentiating feature; good for biamp/triamp setups as well as swarms of subs, something that preamps with at most two outputs fall short on.  Again, best sound quality going all balanced with adapters as needed?

I think in a dedicated, two-channel preamp, I agree with others that a quality remote is a good thing; power/standby, mute, volume controls, source select would be nice but maybe unnecessary considering alternate analog sources are generally devices one has to get out of the chair to set up and use (reel-to-reel, vinyl, even "old fashoned" cd players; anything using physical media really).

I'm thinking something fairly simple (basic analog in/out, minimal number of inputs and outputs) coming in around $1000 as a solid sonic bang for the buck feels about right price-wise.  If you could pack along top-shelf digital input/output and a balanced circuit design for under $2K I think you could turn some heads.  I guess pricing depends on what your vision for your company really is and what you want people to see you as - do you want DAC to trade punches with value leaders at the $10K and under total system crowd (thinking Odyssey here on AC as an example), or do you want to aim more at the high end of the market?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Early B. on 15 Dec 2017, 05:42 am
Keep it simple -- no remote because it significantly drives up cost if done right and if a good quality remote is included (not that plastic crap).

Two inputs, two outputs, one of each is balanced.

$799 price point. At this price, if the preamp blows your customer away, he'll be much more likely to purchase the Cherry amps shortly thereafter.
 

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: mboxler on 15 Dec 2017, 03:17 pm
Sorry if this is OT, and I'm pretty sure this would require an integrated amp due to EMI and such, but...

Will the industry eventually go the route of converting any type of input to PWM and then feeding that signal directly into a PWM amplifier?
In other words...analog/pcm/???--->pwm--->PWM--->filter--->speaker.

Just curious.

Mike
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Shear Bliss VMPS on 15 Dec 2017, 06:49 pm
You people are dreaming if you think Tommy or anyone else can bring a quality class D preamp to fruitation at the prices mentioned here, just not possible. Also if it doesn't offer remote for attenuation with LED readouts would not be for me. Probably why I still run a Classe CP-35 preamp with great results and sound, even my tube Audio Mirror T-61 offers remote attenuation.

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 15 Dec 2017, 07:43 pm
Time to address the elephant in the room....  It's a preamp, probably analog and digital input.  Not Class-D.  The amps, if integrated, like the Stereo Maraschino, would be Class-D, however.

This device is almost 100% sure to have an FPGA running the show.

Regarding "direct digital" amps (PCM -> PWM, etc.).  Been there, done that.  The price goes way up (to facilitate super fancy components required for great audio performance with that topology), or the performance (measured audio wise) goes down.

Thanks as always (:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: smargo on 15 Dec 2017, 08:43 pm
Keep it simple -- no remote because it significantly drives up cost if done right and if a good quality remote is included (not that plastic crap).

Two inputs, two outputs, one of each is balanced.

$799 price point. At this price, if the preamp blows your customer away, he'll be much more likely to purchase the Cherry amps shortly thereafter.
 

couldn't disagree with you more about the remote - in this day and age not having a remote - is like not having a cell phone

its what customers expect if your going to be viable in the future
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 15 Dec 2017, 08:57 pm
couldn't disagree with you more about the remote - in this day and age not having a remote - is like not having a cell phone

No, it's worse than that. I can live without a cell phone, been doing that for over 10 years now. But no remote is a deal breaker. I really don't want an integrated DAC, and it must have at least 2 pairs of single ended inputs and 1 pair of single ended outputs or it's a no go for me.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 15 Dec 2017, 09:25 pm
Just to add a little info....

These days, our most recommended system setup for Maraschino monoblock owners is the simplest, and it skips over the preamp entirely.  We configured the DAC DAC (both TL and HS versions) to drive Maraschino monoblock amplifiers directly while allowing a few dB of clipping at full scale (0dBFS a.k.a. 1FS).  So, this way, you can use a music server (or PC running the appropriate SW, like JRiver) to deliver PCM to the DAC that is scaled (volume control).  PLUS, you can use your phone (or an iPad, iPod Touch, or tablet) as the remote with a simple app like JRemote, and you can control the track and volume from your seat (over wifi).

With SW like JRiver, all formats are supported and converted to PCM easily.  Digital volume requires a few things to work effectively, the most important of which is a really good DAC....

OK, with this in mind, let's keep the conversation going!  Thanks, all for the input and compliments.   :D
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 15 Dec 2017, 09:30 pm
No, it's worse than that. I can live without a cell phone, been doing that for over 10 years now. But no remote is a deal breaker. I really don't want an integrated DAC, and it must have at least 2 pairs of single ended inputs and 1 pair of single ended outputs or it's a no go for me.
Single ended and balanced in/out is no problem.

For the remote, we can just do what Mytek does and use an Apple remote.  It is kind of "plasticy", though, but sleek.

I'm a fan of heavy metal remotes.  No pun intended.

We can discuss the cell phone thing later, but WOW, very interesting stuff!
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: JohnR on 16 Dec 2017, 06:51 am
use an Apple remote.

I believe the new remote (supplied with the Apple TV4 for example) uses different codes. Just something to be aware of maybe :)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: gregfisk on 16 Dec 2017, 07:02 am
Two analog inputs, maybe three. one balanced, one not.

Two outputs same thing.

No Dac.

Volume control is a MUST! Not having one is living in the past. I put it in the same category as not having a TV remote. Volume and balance control on the remote.

Make the case large enough that you have room for the connectors.

an additional feature might be an HT bypass.

$2000.00 or less if realistic?

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 16 Dec 2017, 12:32 pm
Two analog inputs, maybe three. one balanced, one not.

Two outputs same thing.

No Dac.

Volume control is a MUST! Not having one is living in the past. I put it in the same category as not having a TV remote. Volume and balance control on the remote.

Make the case large enough that you have room for the connectors.

an additional feature might be an HT bypass.

$2000.00 or less if realistic?
How important is the "balance control" part of the remote?  That adds a level of difficulty....
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz on 16 Dec 2017, 01:47 pm
So, am I reading that it seems most of the people in thread so far are asking for a simple analog-only preamp?

If a thought early in the thread of possibility of digital inputs still has traction (and would be paired with analog outputs), and the volume control that has been floated around (no pun intended with the FPGA comment) is something that by design is done in the digital domain (reprocessing the original signal, whether done D-D or A-D before being converted D-A for the outputs), unless I'm missing something, all that kind of requires a DAC, and if a DAC needs to be in there anyway, it seems counterproductive not to use a GOOD one (Tommy's words)?  Having digital inputs to that DAC in the device simply means that Tommy's "most recommended" signal path (digital source - digital volume control - DAC - analog amplifier output stage) would be available, with the "added feature" (as an analog preamp) to be able to take input from analog sources (phono stages, tapes, someone's favorite outboard DAC...) as well (analog source - internal ADC - digital volume control - DAC - analog amplifier output stage)?

Although it sounds like there is some interest by people posting in this thread for an analog preamp, maybe some of your existing (amplifier) customers looking to go all-in on your design philosophy are really looking for a more fully-featured integrated than the STM (or at least an equivalent "preamp" section in a case that could be connected to their already purchased outboard amps) with a few more analog inputs for those still using something other than a single, non-digital source?

...or maybe I'm over thinking this and I should just let Tommy put together a nice analog input switcher with an impedance buffer and remote volume control and call it a day. :)



(As an aside, on what seems to be Tommy's common thread of streamlining and shortening signal paths, I'm wondering out loud why there hasn't been produced a DAC DAC 1.5 that builds the USB-SPDIF converter into the DAC itself, thus allowing the shortest possible signal path (no external connectors or variables in cabling) from a USB input to the DAC DAC's native (SPDIF?) input?)

(Taken a step further, starting with the "all pieces are already in place" starting point, it doesn't seem much of a stretch to build an all-digital "integrated" that puts the "most recommended configuration" all in one box, maybe adding a digital volume control so as to not rely on a variable in the quality of digital volume control at the source?  It kind of seems to be more in line with industry trends - DACs that include volume control/"preamp" functionality, or fully integrated software driven digital solutions - but I might be completely wrong. Is the DAC/pre still the "in" thing or is the industry leaning more in the direction of streamer/source/pre so that DACs can be changed more easily at will/whim?)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 16 Dec 2017, 04:44 pm
Two analog inputs, maybe three. one balanced, one not.

Two outputs same thing.

No Dac.

Volume control is a MUST! Not having one is living in the past. I put it in the same category as not having a TV remote. Volume and balance control on the remote.

Make the case large enough that you have room for the connectors.

an additional feature might be an HT bypass.

$2000.00 or less if realistic?

I agree with pretty much everything here but why a balance control? I’ve never had need for one in the past nor do I anticipate I will in the future.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: gregfisk on 17 Dec 2017, 02:24 am
How important is the "balance control" part of the remote?  That adds a level of difficulty....

It's not a deal breaker by any means Tommy, not all songs are in balance and I notice it. They sound better to me if tweaked a little one way or the other depending on the song.

WC, if you don't notice it then you don't have to use it, I find them useful. Right now I'm using a Lampizator Atlantic Dac/Preamp. It doesn't have a balance control but that didn't keep me from buying it. I do miss not having the control on occasion thou. 
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Wind Chaser on 17 Dec 2017, 06:37 am
...not all songs are in balance and I notice it. They sound better to me if tweaked a little one way or the other depending on the song.

Can you point to a few specific recordings where you found the balance is out?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: gregfisk on 17 Dec 2017, 08:43 am
Can you point to a few specific recordings where you found the balance is out?

Not off the top of my head. 
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: timind on 17 Dec 2017, 02:12 pm
This question has been bugging me, what would be "class D" about a preamp? I can understand Digital Amplifier Company building a preamp, just not sure what advantage there would be in sending a low level signal through class D.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz on 17 Dec 2017, 02:23 pm
This question has been bugging me, what would be "class D" about a preamp? I can understand Digital Amplifier Company building a preamp, just not sure what advantage there would be in sending a low level signal through class D.

From Tommy, earlier in this thread:

Time to address the elephant in the room....  It's a preamp, probably analog and digital input.  Not Class-D.  The amps, if integrated, like the Stereo Maraschino, would be Class-D, however.

This device is almost 100% sure to have an FPGA running the show.

Regarding "direct digital" amps (PCM -> PWM, etc.).  Been there, done that.  The price goes way up (to facilitate super fancy components required for great audio performance with that topology), or the performance (measured audio wise) goes down.

Thanks as always (:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 21 Dec 2017, 09:29 pm
How about a digital-out only preamp?  Just thinking out loud.

It would still have analog input(s), driving a high performance ADC.

With more integration comes less flexibility.

This could also be bundled with the DAC DAC (TL or HS) as the analog output option.  Digital volume control, of course (:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: rodge827 on 21 Dec 2017, 10:46 pm
Sounds like a good idea  8)
Digital ins and outs with an internal A-D converter for analog sources. DC powered with a super quiet LPS is a must. :thumb:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 28 Dec 2017, 11:13 am
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?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: rodge827 on 28 Dec 2017, 01:31 pm
Sounds good to me...Will the preamp be able to be used with other dacs? Upsample? Sample rates?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AKLegal on 28 Dec 2017, 02:30 pm
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.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 29 Dec 2017, 04:32 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.

First, thanks for the compliments regarding the In-Line Maraschino Amp!

SPDIF output allows use of the DAC DAC's internally re-clocking SPDIF receiver.  This fempto-clock driven source for the internal IIS interface to the DAC chips makes everything gel for a perfectionist's digital dream!

Of course, we WILL have an HT bypass mode!

Thanks for your kind post.

-Tommy O
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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.

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: rodge827 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)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz 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).
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AKLegal 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.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz 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?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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!

(http://www.audiocircle.com/image.php?id=169167)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz 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.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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.

Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Jonathon Janusz 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.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: Early B. 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?   
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: GregC 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. :)
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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!
Title: DOING IT !!!!
Post by: AmpDesigner333 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 (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 (:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 25 Feb 2018, 08:36 pm
Any thoughts ????

(http://www.audiocircle.com/image.php?id=176699)

Nothing analog inside the DPA!
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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?
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 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....
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: SteveMiller 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!
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: jseipp on 12 Mar 2018, 10:14 pm
I’ve been away from the boards for awhile and have been doing a little catch-up reading.  What strikes me about this thread and the current Kickstarter campaign is how responsive Digital Audio Company has been to their customers from the beginning of the Cherry Amplifier brand almost ten years ago and accelerating into the present.  I have participated in all four previous Kickstarters and have profited through an immense amount of musical enjoyment as a result. 

I am really impressed with the constructive communication that constitutes this thread and with how quickly it has resulted in the design of a new product intended to increase the flexibility of the DAC products already in use.  This Kickstarter campaign once again offers newcomers the opportunity to purchase existing products at a significant discount as well.  I’m probably most impressed with the additional focus on offering upgrades for products purchased through the years and across the entire range, adding to the value of DAC products as long-term investments in making customers’ music sound as fresh as possible.

The continual innovations introduced through the DAC website and through each Kickstarter campaign demonstrate what talented design work can accomplish when focused on the goal of sharing with customers the very best sound while avoiding unnecessary frills at prices that reflect the efficiency of direct sales.  What may not be obvious is the personal service Tommy and Digital Audio Company provide.  If anyone is curious about the products being offered via the Kickstarter campaign I highly recommend getting in touch with them and having any questions you may have answered.  You’ll find yourself speaking with a true music enthusiast who happens to build equipment that makes the pursuit of the best sound so very enjoyable.

No association with or incentive from the company, just a message intended to encourage anyone who is considering it to find out for themselves if the products currently on offer on Kickstarter are a fit for their systems.  When I’ve found the source of something truly special, it’s a pleasure to spread the word to others!   
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 13 Mar 2018, 03:19 am
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!
Regarding the second digital output (each is two channels), we plan to do almost exactly what you're saying, but can't promise any specifics until we have the hardware completed.  Code generation (VHDL) can happen during the PCB assembly lead time.  Individual functions (filters, interfaces, etc.) are already available from past projects.  Some of the processing we plan to do wouldn't be possible with a reasonably priced DSP or even matrix of DSPs.  This is one reason we're using an FPGA.  We can control every last bit precisely this way, removing potential glitches.  Thanks for your kind words!

-Tommy O
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 14 Mar 2018, 03:26 am
One of the "stretch goals" of our current Kickstarter (http://kck.st/2CH4sLB) is to add USB and optical inputs to the DPA.  We haven't decided how many DPA orders will cover the added expense yet.

However, since inexpensive optical to coax converters are readily available, and we already make the Cherry USB, we are torn on this issue!  Here's where your opinion steers development like no place else....

Some have even asked for bluetooth (can't believe I just typed that word).  I have kids, and they love being able to "broadcast" their music to a decent audio system, even though BT's compression is certainly audible as witnessed by many comparisons with the STM ---- headphone jack (from a phone that still has one) vs BT is smack-you-in-the-face obvious for most music and even dialog.  Well, we have no plans to "go there" yet.  When is BT's next update?  Maybe when it's able to transmit stereo 24/96.  I'd be happy with lossless 16/44.  The Cherry BT is on hold indefinitely, but if we were to make something like that, it would have a digital output only, coax.

So, for now we wait to see the results of our Kickstarter.  Several of the "CUSTOM" rewards include the DPA.  We added some demo amps today, by the way.  Something in the rewards may shock you.  Hint: there's only ONE.  Thanks as always for taking the time to visit our circle.
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 26 Mar 2018, 02:28 am
Only 20 hours left:
http://kck.st/2CH4sLB

We are over 440%!   Sooooo close to 500% where the Cherry DPA will get USB and optical inputs. This is what we call a "stretch goal". 
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 27 Mar 2018, 01:28 am
Thanks to our awesome backers, we reached 511% !

So, as  promised, the Cherry DPA will include USB and optical inputs (coax too).

We are honored by the response and look forward to building a wonderful product.

-Tommy O  :D :D :D :D
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 14 May 2018, 09:15 pm
Sorry if this is OT, and I'm pretty sure this would require an integrated amp due to EMI and such, but...

Will the industry eventually go the route of converting any type of input to PWM and then feeding that signal directly into a PWM amplifier?
In other words...analog/pcm/???--->pwm--->PWM--->filter--->speaker.

Just curious.

Mike
Mike,

I was reviewing this thread and saw your post.  Looks like your question wasn't addressed, so....

Performance would be limited by such a device because the PWM at signal level would only be applicable to open loop PWM amplification.  That would result is performance limitations, such as higher THD+N and significantly lower SNR.  We have developed open loop Class-D amplifiers in the past.  In fact, ST Microsystems built their Class-D chip set around open loop "direct digital" Class-D patents that I wrote in the 90s.  We went on to build improved designs, but none that could outperform our hybrid analog/digital modulation technique used in Cherry Amps.

We have tossed around the idea of a new digital-input-only amp for decades.  However, this would probably be using an all-digital version of our modulation technique with super-high-performance A/D converters used for multi-level feedback.  Our target SNR for such a device is 120dB.  Not an easy feat, but our current 130dB+ DAC DAC 2 HS driving a 120dB SNR MEGAschino (or much lower cost Stereo Maraschino) amp directly can achieve the same level of performance, and these products are available now.  We don't do things for the sake of novelty, so we would need to achieve some performance advantage over our current products in order to reconsider.

Thanks for your excellent question.

-Tommy O
Title: Design Update
Post by: AmpDesigner333 on 26 May 2018, 02:25 pm
We have one more major item to decide on....  The display.  We picked one that's graphic and OLED, but we're not sure if there's a MOQ associated with this part.  Since it's a holiday weekend here, the answers will need to wait until next week.

So, we have 4 inputs: COAX1, COAX2, OPT, and USB.  There are two coax outputs.  We plan to use this for a sub crossover (augment/supplement, selectable frequency, selectable phase) and maybe our headphone algorithm....  Maybe.  We're wondering if this will "force us" into a digital headphone amp.  Hmmmmm.  Sounds like fun !

We are also thinking of using an analog volume pot to control the digital volume.  Any thoughts?  I'm partial to knobs, especially the single turn type.

You guys are the KEY to making this product!  The Cherry DPA is a collaborative effort!  My sincere thanks for any suggestions, as always (:
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: BruceSB on 30 Nov 2018, 03:01 am
No posts for a while.
I wonder if we can have an update on how things are coming along?
Maybe even a picture?
I also wonder about the possibility of replacing one of RCA analogue inputs to a balanced input?
Thinking that there a number of good phono preamps with balanced outputs & anyway balanced good anyway?!
Another possibility is an additional analogue input that is balanced but that increases the price!
Thanks.
Bruce
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 30 Nov 2018, 11:26 pm
No posts for a while.
I wonder if we can have an update on how things are coming along?
Maybe even a picture?
I also wonder about the possibility of replacing one of RCA analogue inputs to a balanced input?
Thinking that there a number of good phono preamps with balanced outputs & anyway balanced good anyway?!
Another possibility is an additional analogue input that is balanced but that increases the price!
Thanks.
Bruce
Bruce,

We are planning an update very soon, to be broadcast "on all channels"....

In the meantime, I should mention that the Cherry DPA is a DIGITAL ONLY product.  Digital Audio in and out.  The Cherry DPA allows input selection, volume control with gain, an IR remote, and several DSP functions.  It is meant to drive one or two Cherry DAC DACs (version 1 or 2, TL or HS), although other DACs can be used.  Systems with direct DAC-to-amp drive will be enabled by the Cherry DPA even for non-volume-controlled sources (like CD transports).  We plan to offer a Cherry ADC for conversion to digital (most likely single ended inputs), although products that can handle this function at low cost are out there currently.  I'm very excited about the Cherry DPA!  Thanks for your kind post.

-Tommy O
Title: Re: Hey Tommy, any plans to make a Class D preamp?
Post by: AmpDesigner333 on 19 Dec 2018, 03:02 pm
Update: We are working hard on the design, and plan for production early 2020.

New panels! -- see note below

(https://www.audiocircle.com/image.php?id=188157)

(https://www.audiocircle.com/image.php?id=188158)

NOTE: We received much feedback about the design, and we're changing the nature of the product.  Stay tuned for updates as they are available!