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Topping A90 Discrete Review (Headphone Amp & Preamp)

Rate this Headphone Amp/Pre-amp

  • 1. Poor (headless panther)

    Votes: 9 3.1%
  • 2. Not terrible (postman panther)

    Votes: 9 3.1%
  • 3. Fine (happy panther)

    Votes: 50 17.3%
  • 4. Great (golfing panther)

    Votes: 221 76.5%

  • Total voters
    289

raif71

Major Contributor
Joined
Sep 7, 2019
Messages
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Hi...any of you have both a90 and a90 discrete? How do they sound and importantly does the discrete have more volume headroom compared to the a90 ? Thanks
 

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
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Gold Coast, Queensland, Australia
What does that mean?

The load for the discrete version was essentially nothing at 200,000 Ohms. The load for the OPAMP based unit was 600 Ohms, 333 times lower... At high fequencies, where the feedback is lower, the load is also more demanding at 600R.

I would expect somewhat different results for 600R loads. As such, you cannot compare the two on the same playing field.

It's just something Amir missed when setting the AP's input impedance. He's normally pretty consistent.
 

tritopia

Member
Joined
Apr 30, 2022
Messages
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Likes
47
The A90D greatly expands the left and right sides of the sound. maybe almost 200%?? Comparison with preamplifier using Nutube tube or LA90's integrated amp mode. It's amazing.

Could it be the effect of ladder volume? Is it because the compensation value of the PAN processing is slightly different?




* D90SE -> Bal out -> A90D -> LA90 Bal. Input
: L --------------------- C ---------------------- R


* D90SE -> unBal out -> Nutube preamp -> LA90 unBal. Intput (The same is true for LA90's integrated amp mode.)

: L -------------- C -------------- R

DSC08474.jpeg
 

raif71

Major Contributor
Joined
Sep 7, 2019
Messages
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1,829
The A90D greatly expands the left and right sides of the sound. maybe almost 200%?? Comparison with preamplifier using Nutube tube or LA90's integrated amp mode. It's amazing.

Could it be the effect of ladder volume? Is it because the compensation value of the PAN processing is slightly different?




* D90SE -> Bal out -> A90D -> LA90 Bal. Input
: L --------------------- C ---------------------- R


* D90SE -> unBal out -> Nutube preamp -> LA90 unBal. Intput (The same is true for LA90's integrated amp mode.)

: L -------------- C -------------- R

View attachment 216534
are you talking about soundstage?
 

cheapmessiah

Active Member
Joined
Jun 10, 2021
Messages
151
Likes
106
Location
Mordor
The A90D greatly expands the left and right sides of the sound. maybe almost 200%?? Comparison with preamplifier using Nutube tube or LA90's integrated amp mode. It's amazing.

Could it be the effect of ladder volume? Is it because the compensation value of the PAN processing is slightly different?




* D90SE -> Bal out -> A90D -> LA90 Bal. Input
: L --------------------- C ---------------------- R


* D90SE -> unBal out -> Nutube preamp -> LA90 unBal. Intput (The same is true for LA90's integrated amp mode.)

: L -------------- C -------------- R

View attachment 216534

No.
 

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
8,679
Likes
10,757
The A90D greatly expands the left and right sides of the sound. maybe almost 200%?? Comparison with preamplifier using Nutube tube or LA90's integrated amp mode. It's amazing.

Could it be the effect of ladder volume? Is it because the compensation value of the PAN processing is slightly different?




* D90SE -> Bal out -> A90D -> LA90 Bal. Input
: L --------------------- C ---------------------- R


* D90SE -> unBal out -> Nutube preamp -> LA90 unBal. Intput (The same is true for LA90's integrated amp mode.)

: L -------------- C -------------- R

View attachment 216534
Bal in. Bal out. You most likely have a louder/stronger signal, you're perceiving it as better. Most likely explanation.
 

tritopia

Member
Joined
Apr 30, 2022
Messages
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Likes
47
Bal in. Bal out. You most likely have a louder/stronger signal, you're perceiving it as better. Most likely explanation.

The volume in both situations is matched and compared. The LA90's integrated amp mode is the same balanced situation.

Similar to how other member felt with the D90SE + Pre90 combination.

 

tritopia

Member
Joined
Apr 30, 2022
Messages
41
Likes
47
Bal in. Bal out. You most likely have a louder/stronger signal, you're perceiving it as better. Most likely explanation.
In panning processing, the center sound image is compensated by -6dB, -3dB or a compromise of -4.5dB.
If the manufacturer uses a volume with slightly different (Like -4.6dB? or -4.75dB?) compensation values, the sound image in the center becomes smaller and the sound image on the left and right expands. As a result, I think the left and right width of the sound image can be widened.




When centered (at 12 o'clock), the law can be designed to send −3, −4.5 or −6 decibels (dB) equally to each bus. "Signal passes through both the channels at an equal volume while the pan pot points directly north." If the two output buses are later recombined into a monaural signal, then a pan law of -6 dB is desirable. If the two output buses are to remain stereo then a law of -3 dB is desirable. A law of −4.5 dB at center is a compromise between the two.
 
Last edited:

Haruko

Member
Joined
Sep 14, 2021
Messages
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Likes
59
In panning processing, the center sound image is compensated by -6dB, -3dB or a compromise of -4.5dB.
If the manufacturer uses a volume with slightly different (Like -4.6dB? or -4.75dB?) compensation values, the sound image in the center becomes smaller and the sound image on the left and right expands. As a result, I think the left and right width of the sound image can be widened.




When centered (at 12 o'clock), the law can be designed to send −3, −4.5 or −6 decibels (dB) equally to each bus. "Signal passes through both the channels at an equal volume while the pan pot points directly north." If the two output buses are later recombined into a monaural signal, then a pan law of -6 dB is desirable. If the two output buses are to remain stereo then a law of -3 dB is desirable. A law of −4.5 dB at center is a compromise between the two.
L/R and Mid-Side processing are two different things as long as you add L and R channel equally the result will always be the same only the volume will change... in mid/side tho you are evaluating differences between channels and for side processing you are inverting one channel to null the same information in both channels thus resulting in Side channel. This requires processing tho and is not as simple as mixing two channels
 

tiramisu

Member
Joined
Jun 24, 2022
Messages
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Likes
74
This device deserves a Lexan top and RGB LEDs. A fully balanced discrete headphone amp PCB needs to be shared with the world. It is a work of art. Put it on the wall and shine lights on it. I have had my L50 for almost a week and I don't notice it at all. I'm just hearing the music. A wonderful little piece of gear.
 

mrjayviper

Member
Joined
Jun 27, 2022
Messages
46
Likes
2
any recommended DAC for this amp? (or any would suffice since the measurements for recent DACs are all good and beyond hearing anyway?)
 

carlcamper

Member
Joined
Aug 1, 2020
Messages
92
Likes
87
Location
Cavite, Philippines
any recommended DAC for this amp? (or any would suffice since the measurements for recent DACs are all good and beyond hearing anyway?)
For matching looks, the Topping D90LE is good, although I'm currently using the Topping D10 Balanced, and will also try the SMSL D-6 with a new AKM chip just for comparison.
 

Haruko

Member
Joined
Sep 14, 2021
Messages
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59
any recommended DAC for this amp? (or any would suffice since the measurements for recent DACs are all good and beyond hearing anyway?)
if money is not a problem Topping D90LE, if you want to save money Topping D30 Pro
 

August

Active Member
Joined
May 4, 2019
Messages
154
Likes
185
A90 Discrete version V2.0 firmware update
What's updated:

1, Added a new feature allowing 5 different volume curves to select, providing different ranges and steps.
Users can change volume curves by pressing "B" on the remote. The volume curves and the conversion
table is available here. When the curve is changed, the volume will be reset to -80dB.

2, Added a procedure to alter the gain setting without using the remote. Users can change the gain to
high by pressing the volume knob and turning it clockwise by 2 steps in 1.5 seconds while the knob is pressed.
To change the gain to low, press the volume knob and turning it counterclockwise by 2 steps.
Pressing the knob for 1.5 seconds without turning turns off the device.

3, Fixed incorrect "-4" fault code indication.
 

4udio

Member
Joined
Oct 23, 2020
Messages
70
Likes
42
A90 Discrete version V2.0 firmware update
What's updated:

1, Added a new feature allowing 5 different volume curves to select, providing different ranges and steps.
Users can change volume curves by pressing "B" on the remote. The volume curves and the conversion
table is available here. When the curve is changed, the volume will be reset to -80dB.

2, Added a procedure to alter the gain setting without using the remote. Users can change the gain to
high by pressing the volume knob and turning it clockwise by 2 steps in 1.5 seconds while the knob is pressed.
To change the gain to low, press the volume knob and turning it counterclockwise by 2 steps.
Pressing the knob for 1.5 seconds without turning turns off the device.

3, Fixed incorrect "-4" fault code indication.
Since Gain "issue" is no more then I'll go for this device.
 

carlcamper

Member
Joined
Aug 1, 2020
Messages
92
Likes
87
Location
Cavite, Philippines
A90 Discrete version V2.0 firmware update
What's updated:

1, Added a new feature allowing 5 different volume curves to select, providing different ranges and steps.
Users can change volume curves by pressing "B" on the remote. The volume curves and the conversion
table is available here. When the curve is changed, the volume will be reset to -80dB.

2, Added a procedure to alter the gain setting without using the remote. Users can change the gain to
high by pressing the volume knob and turning it clockwise by 2 steps in 1.5 seconds while the knob is pressed.
To change the gain to low, press the volume knob and turning it counterclockwise by 2 steps.
Pressing the knob for 1.5 seconds without turning turns off the device.

3, Fixed incorrect "-4" fault code indication.
Whats the password for the firmware download?
 

ethanc

New Member
Joined
Jul 7, 2022
Messages
3
Likes
1
Got the A90D on Monday. Yesterday, I was experiencing random LOUD pops from my right powered speaker connected via xlr out. They were intermittent and sporadic (maybe every minute or two). A few of the pops also produced a fault code of “-5” on the LED display. It is connected to RME ADI-2. Coincidentally, when I first opened the unit and plugged it in, it showed “-5” and would not function/operate until I put batteries into the remote and pressed a button, then it went to showing volume level. Any clues from anyone? Is this a faulty unit? Should I try the firmware update? I’ve gone back to my previous amp in the meantime, don’t want to risk blowing up my LCD-5’s..
 
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enricoclaudio

Senior Member
Manufacturer
Joined
Jan 7, 2021
Messages
488
Likes
757
Got the A90D on Monday. Yesterday, I was experiencing random LOUD pops from my right powered speaker connected via xlr out. They were intermittent and sporadic (maybe every minute or two). A few of the pops also produced a fault code of “-5” on the LED display. It is connected to RME ADI-2. Coincidentally, when I first opened the unit and plugged it in, it showed “-5” and would not function/operate until I put batteries into the remote and pressed a button, then it went to showing volume level. Any clues from anyone? Is this a faulty unit? Should I try the firmware update? I’ve gone back to my previous amp in the meantime, don’t want to risk blowing up my LCD-5’s..

Pretty sure @JohnYang1997 would tell you what that error code means as he is the designer of the A90/A90D. But if you don’t get any response from him, I would definitely contact the dealer and ask for a replacement.
 
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