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Review: Resonessence Labs Invicta - new high end DAC/amp/playback system - Page 4

post #46 of 715
Thread Starter 

I just got an email from Mark at Resonessence and figured I'd share the info:

 

He says they are now shipping the final production version of Invicta. The system has an improved user interface, improved headphone output (I assume more power as he had talked about earlier), USB 2.0 support, AIFF file format support, as well as the remote which was lacking on my pre-production unit. They are currently working on a display via HDMI feature and hope to have that finished by October, when they will be attending the RMAF show in Denver. They will be presenting a number of other products which are as yet unannounced. 

 

With CanJam happening at the same venue, I encourage HeadFiers to stop by room 418 and say hello the Resonessence folks. Tell them I sent you and get the Invicta for half price! Ok, maybe not..... but they are sponsoring three technical presentations given by the inventors of the Sabre DACs, which should be rather illuminating for anyone interested. I won't be able to attend but I'd love to hear other impressions if someone gets a chance to stop by. 

post #47 of 715

Hi All,

 

   I am on the engineering team at Resonessence labs and wanted to post a link to our FAQ where we have addressed the AD797 JFET input issue.     Please feel free to check it out, we tried to go into some detail to show that it really is a JFET input.

 

Also, we are very appreciative of any feedback / opinions / suggestions on our products.  

 

http://resonessencelabs.com/?page_id=314

 

 

 

 

Regards,

 

  Resonessence Labs Engineering Team.

post #48 of 715
Quote:
Originally Posted by EngAtRes View Post

Hi All,

 

   I am on the engineering team at Resonessence labs and wanted to post a link to our FAQ where we have addressed the AD797 JFET input issue.     Please feel free to check it out, we tried to go into some detail to show that it really is a JFET input.

 

Also, we are very appreciative of any feedback / opinions / suggestions on our products.  

 

http://resonessencelabs.com/?page_id=314

 

 

 

 

Regards,

 

  Resonessence Labs Engineering Team.



Thanks for pointing me with more information.

 

Im in no position to argue with you and have no in tentions to do so. 

 

You have explained in link that the circuit of the AD797 clearly shows bipolar devices for Q1 and Q2, this does not qualify it to be placed in the categry of a Jfet device as you have specified in your specification.  You can designed basic circuits and conditioned the AD 797 to give you results that reach outcomes close to that of a Jfet but this doesn't give you the justification to class this as a Jfet device.  Only the designer or AD can do this.  Why? because all the other opamps that have this semmetrical differential bipolar device like the one used in AD 797 and it is a commom circuit that most manufacturers such as AD BB and LT uses places this typical circuit as bipolar and not Jfet.  If you do continue to document the AD 797 as a Jfet then that means all the other manufacturers must do the same,  If that is the case then what do you call a differential circuit with real Jfets instead of bipolar?  Do you see the can of worms you are opening up!

I like to explaned that the AD797 is not a Jfet or fet input device to all involved in Head Fi with no electronics background.

 

Feedback is commonly used in most opamps to control non lineararities.  It provide stability under normal operating conditions and most amplifiers will have some feedback.  The AD797 requires  feedback to be stable.  Q1 an Q2 are place in a differential arrangement for better noise rejection than a normal single stage.  Q1 and Q2 of an AD797 are normal transistors with a base, collector and emitter.  the Base and emitter will have a 0.6-0.7 volts drop across it when it is correctly powered up, therefore require bias current to control the emitter/collector. therefore AD do not class this as a jfet device

A fet device is differently drawn in circuits and has a gate, drain and source compared to a  bipolar; base, collector and emitter.  The gate requires no current for the device to switch on/off at the drain/source therefore it behaves like a valve.   Yes you can say that a fet is a SS valve!

Devices such as AD 825, AD 8627-1/8637-1.AD 8065, OPA 2134, OPA 627/637/827. are all Jfet devices, why because the are outlined and classed as jfets according to there data sheets and there electrical characteristics are typical of a jfet.

Devices such as AD797, 827/826 , OPA 1611 are not classified as jfets because there electrical characteristics are typical of a bipolar device.   Infact the OPA 1611 says it is a bipolar!!!

I dont care if you classified the AD797 as a jfet because I dont give a rats. I know that the AD 797 is a bipolar device and not a Jfet.  What team invicta has to worry about is the legality of quoting and placing the AD 797 as a jfet because your competitors and curtain parts of the world will be scrutinising it like I have!

 

post #49 of 715

We take your point. As you can see from our FAQ response, we now say no more than ADI says
about this amplifier in their public documents. Lets agree that they use the phrase
"special input transistors" as noted in the datasheet on page 12 and leave it at that.

So to all the readers of this posting, ADI does not say that the AD797 is a FET input device
and Resonessence should not have confused the readers by claiming that it is.

To learn more about the AD797 and why it differs from the OPA1611 etc interested readers
can refer to the inventors patent: 5,166,637 and for more about op-amps in general
Walter Jung of ADI has an excellent historical overview.

 

 

Regards,

 

  Resonessence Labs Engineering Team.

post #50 of 715



 

Quote:
Originally Posted by EngAtRes View Post

We take your point. As you can see from our FAQ response, we now say no more than ADI says
about this amplifier in their public documents. Lets agree that they use the phrase
"special input transistors" as noted in the datasheet on page 12 and leave it at that.

So to all the readers of this posting, ADI does not say that the AD797 is a FET input device
and Resonessence should not have confused the readers by claiming that it is.

To learn more about the AD797 and why it differs from the OPA1611 etc interested readers
can refer to the inventors patent: 5,166,637 and for more about op-amps in general
Walter Jung of ADI has an excellent historical overview.

 

 

Regards,

 

  Resonessence Labs Engineering Team.


I am happy with the term " Special Transistors",  you're going to have to apply this term to the specification of your product on you web site and other documentation that is currently referring the AD 797 as a jfet device!
 

 


Edited by ecohifi - 8/24/11 at 1:44pm
post #51 of 715
Quote:
Originally Posted by EngAtRes View Post

To learn more about the AD797 and why it differs from the OPA1611 etc interested readers
can refer to the inventors patent: 5,166,637 and for more about op-amps in general
Walter Jung of ADI has an excellent historical overview


If you guys would like to learn more about op-amps in general then reading the datasheets

would definitely help. For example on your FAQ you say this:

 

Analog Devices appear to have the ideal input device (at least for low impedance sources)

that has the very low voltage noise of a bipolar device, and the very low input current (hence

low input current noise) of a FET.

 

TI's lowest noise JFET input op-amp, the OPA827 has an input bias current spec of 50pA

(max). That's not in the same ballpark as bipolar op-amps, which are typically in the nA

range - as you note for the AD797. 'Special' input bi-polar transistors have been employed

in some op-amps since the days of the LM308 (now discontinued). They're called 'super-beta'

and even the LM308's spec for bias current is measured in nA.

 

post #52 of 715
Quote:
Originally Posted by Sapientiam View Post




If you guys would like to learn more about op-amps in general then reading the datasheets

would definitely help. For example on your FAQ you say this:

 

Analog Devices appear to have the ideal input device (at least for low impedance sources)

that has the very low voltage noise of a bipolar device, and the very low input current (hence

low input current noise) of a FET.

 

TI's lowest noise JFET input op-amp, the OPA827 has an input bias current spec of 50pA

(max). That's not in the same ballpark as bipolar op-amps, which are typically in the nA

range - as you note for the AD797. 'Special' input bi-polar transistors have been employed

in some op-amps since the days of the LM308 (now discontinued). They're called 'super-beta'

and even the LM308's spec for bias current is measured in nA.

 


Maybe we all stick to basic electronics and remain in the real world as the AD797 basic schematics do not have any fet input devices drawn in, again ADI has not class this as a Fet in its public documents.  If you class the AD 797 as having fet inputs then you should class both bipolar and fet op amps as being fet input.  Like I said you can have a device that produces low input noise or current that is equal to a fet but dont call them fets as both fet/Bipolar are different in electrical characteristics.  Is a Fet a Valve? we all know the answer to that.  Again only the designer and ADI can revise the ducuments and reclass the AD797.

post #53 of 715
Quote:
Originally Posted by ecohifi View Post

 Again only the designer and ADI can revise the ducuments and reclass the AD797.

As it happens, after I read the claim on their site about the AD797 having FET inputs I PM'd the designer of that chip (he's fairly active on diyaudio) and put the question to him directly. After he'd calmed down a bit he said it was probably a misunderstanding on the part of the Resonessence engineers or their boss. The head honcho is apparently buddies with a senior guy at ADI (if not the CEO). They've since revised their website which is a positive step.
 

 

post #54 of 715
Quote:
Originally Posted by axw View Post

 

If still not convinced, this is what happened with NuForce:
 
Their single-Sabre designs (uDAC, HDP) applied "double jitter-reduction mechanism at data level and at oversampling filter stage".

 


Can someone please explain to me that after all these claims on the how good the sabre 9018 can reduced jitter, why does the chip need to be power cycled off/on to reset a lock out from erroneous data where other chips actually shows audio distortion and auto correct itself once quality signal is restore?
 

 

post #55 of 715
Thread Starter 
Quote:
Originally Posted by ecohifi View Post




Can someone please explain to me that after all these claims on the how good the sabre 9018 can reduced jitter, why does the chip need to be power cycled off/on to reset a lock out from erroneous data where other chips actually shows audio distortion and auto correct itself once quality signal is restore?
 

 


Is that the case for every instance where the ES9018 is used? Or just certain products?

 

Either way, I don't think that is necessarily the best indicator of jitter reduction capabilities. Jitter is difficult to properly test when you get down to very low levels, but it CAN be tested. If real, the issue you are talking about would be more of an operational inconvenience than anything else. 

 

post #56 of 715

Another fantastic review - you are quickly becoming the new Skylab here :) 

post #57 of 715
Thread Starter 
Quote:
Originally Posted by vrln View Post

Another fantastic review - you are quickly becoming the new Skylab here :) 



Nah, Skylab is still the one and only Skylab, and always will be. I'm just doing my part and having some fun in the process. 

post #58 of 715

Has anyone on this forum (or others) received or placed an order for the Invicta dac?   If anyone has actually received one, what was the turnaround time from order to delivery?  Based on the splendid review by project86, this dac indeed looks quite promising but I would be slightly "nervous" about ordering from a relatively new company with little track record to date.

post #59 of 715
Thread Starter 
Quote:
Originally Posted by twsmith View Post

Has anyone on this forum (or others) received or placed an order for the Invicta dac?   If anyone has actually received one, what was the turnaround time from order to delivery?  Based on the splendid review by project86, this dac indeed looks quite promising but I would be slightly "nervous" about ordering from a relatively new company with little track record to date.



I haven't read any other user reports myself, but honestly I haven't really looked for them. When I last heard from Mark Mallinson (last month) he said they had been shipping the finalized production models and were actually increasing production to meet demand. But I guess I have no way to verify that.

 

Since they are attending as well as sponsoring three technical presentations at the upcoming RMAF, I suspect we will hear more about them soon enough. 

post #60 of 715
Quote:
Originally Posted by project86 View Post




Is that the case for every instance where the ES9018 is used? Or just certain products?

 

Either way, I don't think that is necessarily the best indicator of jitter reduction capabilities. Jitter is difficult to properly test when you get down to very low levels, but it CAN be tested. If real, the issue you are talking about would be more of an operational inconvenience than anything else. 

 


Since most products eccept the Anedio D1 which uses a circuit to limit jitter, the coax S/PDIF is feed directly into the chip as it is able to accept in directly,  Alex Yeung fromm EE and Bill from Morningstar has confirmed that there mini max require a cycle off/on to reset a signal lockout that is due to jitterish and errorneous data in the coax in.  There are also other people from other sites confirming this issue that the sabre chip requires high quality signal to work unlike other BB or WM chips that require a receiver chip to convert the coax signal. Confirmation of  evidence such as this has been mounting that the sabre chip is not as immune to jitter or errorneous data as they have claim.

 

Or, I could have a faulty unit that is trgger happy to pissed me off!  A replacement is on the way!
 

 

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