[aboroth00]

   
Did you ever try this:
 
"In my opinion, the HA-1 discrete analog path in the headphone stage sounds so good that I ended up using that output for headphone and as a line out to my various amps. With a simple audiophile 1/4-inch-to-RCA output adapter, the HA-1’s excellent, airy, detailed sound could be carried over to speaker listening. The op-amp enabled line outs are good, but the headphone section is exceptional — more space around the instruments, as delivered by 24-bit."
 
http://everythingaudionetwork.blogspot.co.nz/2014/07/audiophile-review-oppos-ha-1.html
 
?

Actually I have not.  My main system is fully balanced and I use balanced interconnects whenever possible.  Usually when you hear 6.35mm or 3.5mm to RCA it's antithetical to "audiophile." However, I think you may have a good point since the headphone output is discrete when compared to the outputs.  Unfortunately I don't own any "audiophile" 1/4" to RCA's.  For my purposes as a desktop setup, the best sound from my speakers isn't critical as it is in my main setup.  Even though it might sound better, I highly doubt many audiophiles out there would use the HA-1 as a preamp through its headphone section though.

 

[Hooster]

, I highly doubt many audiophiles out there would use the HA-1 as a preamp through its headphone section though.

 
I do too. They tend to be a dogmatic bunch.

 

[aboroth00]

   
I do too. They tend to be a dogmatic bunch.

Mhhmm.  So the question is:  can you hear the difference between the two?

 

[Hooster]

  Mhhmm.  So the question is:  can you hear the difference between the two?

 
The answer is, I am not deaf yet, so I sure can. The class A headphone output takes bass and dynamics up a level.
 
I don't quite understand why Oppo bothered with the op amps at all. I would simply have it switching between the line out and the headphone amp and use the headphone amp to drive the line out. The way the Oppo is currently configured there is an option to listen through headphones and speakers at the same time, with op amps driving the line outs and the class A headphone amp driving the headphones. To most people this is totally pointless. Oppo could have made the HA-1 cheaper and better by simply omitting the op amps.

 

[aboroth00]

   
The answer is, I am not deaf yet, so I sure can. The class A headphone output takes bass and dynamics up a level.
 
I don't quite understand why Oppo bothered with the op amps at all. I would simply have it switching between the line out and the headphone amp and use the headphone amp to drive the line out. The way the Oppo is currently configured there is an option to listen through headphones and speakers at the same time, with op amps driving the line outs and the class A headphone amp driving the headphones. To most people this is totally pointless. Oppo could have made the HA-1 cheaper and better by simply omitting the op amps.

Well I'm not intimately familiar with the HA-1's circuitry so I can't give you definitive answers.  But if you were to have the HA-1 have the ability to switch between the line out and headphone amp, you'd have to implement another circuit.  Then to have a mute function, you would have to install a mute circuit as well.  

Also, I would imagine Oppo intended the line outs to drive very high impedance amplifiers and not relatively low impedance headphones.

 

[john57]

  Also, I would imagine Oppo intended the line outs to drive very high impedance amplifiers and not relatively low impedance headphones.

op amps are fine for driving the pre-amp outputs since higher current is not needed to drive high impedance devices. For the same reason you do not use speakers outputs of a amp to drive a input of a receiver or another pre-amp. Each of the HA-1 line outputs, the RCA and the balanced are driven by separate op-amps.

 

[Hooster]

 

Well I'm not intimately familiar with the HA-1's circuitry so I can't give you definitive answers.  But if you were to have the HA-1 have the ability to switch between the line out and headphone amp, you'd have to implement another circuit.  Then to have a mute function, you would have to install a mute circuit as well.  

Also, I would imagine Oppo intended the line outs to drive very high impedance amplifiers and not relatively low impedance headphones.

Since when did you need a circuit to mute something? And, what would be the function of this other circuit that they would "have to" implement?
 
A circuit breaker mutes. A switch switches between outputs.

 

[aboroth00]

 
Since when did you need a circuit to mute something? And, what would be the function of this other circuit that they would "have to" implement?
 
A circuit breaker mutes. A switch switches between outputs.

Sorry my brain was thinking hifi tube preamps, while the preamp needs to be muted while the relays are switching.  A mute circuit: http://www.transcendentsound.com/Transcendent/Mute_Circuit.html.  They are pretty darn common.  

If you were to jump the line outs from the headphone output, both the line out and the headphone output would be playing simultaneously.  This is the way it was implemented in my Burson Conductor SL to let it serve as a preamp.  So if you would not like the two to be playing simultaneously at all times, Oppo would have to add another circuit.  That is my understanding of the matter.  But i'm not expert at this circuitry business.

 

[aboroth00]

  op amps are fine for driving the pre-amp outputs since higher current is not needed to drive high impedance devices. For the same reason you do not use speakers outputs of a amp to drive a input of a receiver or another pre-amp. Each of the HA-1 line outputs, the RCA and the balanced are driven by separate op-amps.

That's correct.  What would the disadvantage of using the headphone output to drive the line outs if Oppo had decided to jump the headphone output to RCA's for example?  The headphone output would suffer from a poorer SNR but it should be negligible seeing that they are >100db.  Also, the headphone output impedance is 0.5 ohm, and as long as the amp's input impedance is high enough which it should be, I can't see the problem there as well.  

 

 

[Hooster]

  That's correct.  What would the disadvantage of using the headphone output to drive the line outs if Oppo had decided to jump the headphone output to RCA's for example?  The headphone output would suffer from a poorer SNR but it should be negligible seeing that they are >100db.  Also, the headphone output impedance is 0.5 ohm, and as long as the amp's input impedance is high enough which it should be, I can't see the problem there as well.  

 

 
There is in fact no problem. The power amp's input impedance is far higher than any headphone and there is no audible noise. It just works. The only disadvantage I can see is that you can not simultaneously run an output to a power amp and an output to headphones if you where to get rid of the section dedicated to driving the power amp, but why would anyone want to run speakers and cans at the same time?
 
On second thoughts, there is one thing I can think of. There may be some industry standard regarding the max output of a so called line output. Using an output that is designed to drive headphones may make a higher than desirable output possible. Essentially a headphone output will probably not comply with industry standards for a line out. This is no problem in practice, as long as the user knows what he or she is doing. This standard would explain why Oppo does not use the headphone amp to drive the line out.

 

[aboroth00]

   
There is in fact no problem. The power amp's input impedance is far higher than any headphone and there is no audible noise. It just works. The only disadvantage I can see is that you can not simultaneously run an output to a power amp and an output to headphones if you where to get rid of the section dedicated to driving the power amp, but why would anyone want to run speakers and cans at the same time?
 
On second thoughts, there is one thing I can think of. There may be some industry standard regarding the max output of a so called line output. Using an output that is designed to drive headphones may make a higher than desirable output possible. Essentially a headphone output will probably not comply with industry standards for a line out. This is no problem in practice, as long as the user knows what he or she is doing. This standard would explain why Oppo does not use the headphone amp to drive the line out.

I believe you are thinking the opposite.  The line out on a headphone output has a much lower voltage than a typical preamp line out voltage.  You need less voltage to drive headphones than a typical line out voltage of lets say a cd player.  But that shouldn't pose a problem for most amplifiers as the headphone out jack of the Oppo should be enough to reach the full output of the amp.  
 
The only disadvantage I could think of is worse distortion and noise when compared to a well implemented line stage preamp.

 

[Hooster]

 
The only disadvantage I could think of is worse distortion and noise when compared to a well implemented line stage preamp.

 
I will just have to put up with that....
 
"Spec wise, the headphone amp section via digital input boasts a 120 dB dynamic range and 111 dB S/N. The analog in/HP out are a few dB less in performance. Distortion is extremely low at any input/ output configuration."
 
http://everythingaudionetwork.blogspot.co.nz/2014/07/audiophile-review-oppos-ha-1.html
 
 

Specification	Condition	XLR Input - Balanced Output	RCA Input - 6.35 mm Output
Maximum Output Power (Per Channel)	Into 600 Ohm	2400 mW	600 mW
Into 32 Ohm	3000 mW	3500 mW
Rated Output Power (Per Channel)	Into 600 Ohm	800 mW	200 mW
Into 32 Ohm	2000 mW	500 mW
Frequency Response	10 Hz – 200 kHz (+0/-1 dB) 20 Hz – 20 kHz (+0/-0.04 dB)	10 Hz – 200 kHz (+0/-1 dB) 20 Hz – 20 kHz (+0/-0.04 dB)
THD+N at 1k Hz (A Weight, 20 Hz – 20 kHz)	Rated Power	< 0.0018% (< -95 dB)	< 0.0056% (< -85 dB)
50 mW	< 0.001% (< -100 dB)	< 0.0022% (< -93dB)
Channel Separation	> 120 dB	> 90 dB
Signal-to-Noise Ratio (A Weight, 20 Hz – 20 kHz)	> 111 dB	> 111 dB
Dynamic Range (1 kHz -60 dB, A Weight, 20 Hz – 20 kHz)	> 120 dB	> 115 dB
Output Impedance	0.5 Ohm	0.7 Ohm

 

[Hooster]

I was pretty much right. It has to do with "compatibility concerns". From Oppo:
 
 
"XXXX,

The ability to be Class-A all the way through, without the need to use OP-AMPS for the analog outputs, is something that some of asked for, but due to compatibility concerns, we are not yet looking to develop such a product.

Best Regards,

Customer Service
OPPO Digital, Inc.
2629B Terminal Blvd.
Mountain View, CA 94043
Service@oppodigital.com
Tel: 650-961-1118
Fax: 650-961-1119"

 

[jramossurg2002]

Hi
 
I got my HA-1 this week and have been enjoying it thoroughly.  The build quality is impressive as is the functionality.  I would appreciate some advice from fellow members who may use a similar setup to mine.
I am using JRiver Media Center 20, Windows 8.1 64bit Prof, USB connection to HA-1 and Sennheiser HD-800's.
I installed the Oppo USB drivers and selected this as the default driver in Windows.  JRiver picks this up and gives me 4 options for the Oppo - Oppo HA-1 USB Audio 2.0 DAC ASIO, WASAPI, kernel streaming and Direct Sound.  Is any one of these thought to be the best sounding?  I have briefly tried them all but AFAICT only the ASIO and WASAPI will play both PCM and DSD natively.
 
Something else I noted is that with my HD-800's connected to the single ended input, the volume (high gain setting) was quite low.  I then changed to a balanced cable for the HD-800 and the volume improved.  Even with the balanced connection, I need to turn up the volume to about 3 or 4 o'clock (-2dB to 0dB) to get a loud enough volume with certain tracks.  My iFi USB headphone amp seems to drive the HD-800's more easily with the average volume setting at about 1o'clock!  My system and JRiver volume is 100%.
 
any comments or advice is appreciated
 
regards
 
Jose

 

[john57]

For J.River I have the volume control within set for internal. This allows J.River to bypass windows volume control and uses the 64bit J.River volume control. Since playing back DSD is at full volume and you still need to turn up the volume pot on the HA-1?  Have you already switch back and forth the high gain setting on the HA-1 display? With my Alpha Prime I never use the volume control on the Ha-1 any higher than 11:00,