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Topping A70 Pro HP & Preamp Review

Rate this preamplifier and headphone amp:

  • 1. Poor (headless panther)

    Votes: 16 4.2%
  • 2. Not terrible (postman panther)

    Votes: 8 2.1%
  • 3. Fine (happy panther)

    Votes: 42 11.1%
  • 4. Great (golfing panther)

    Votes: 312 82.5%

  • Total voters
    378
Earlier in this thread, in fact. Page 32 I think? There's a posted video that shows the popping and a follow up post from the same user mentioned that the driver wasn't the same afterward. There's a few other anecdotal reports that I had but I've sadly lost them amongst the hundreds of tabs I had open while researching into this.

Ahh, my bad about the volume control, I used the wrong terminology. I really meant "not potentiometer based" as that's the current issue I have with my 789.

And hmm, well, I may just bite the bullet and give it a shot. Here's a question for you, as you seem to be the most knowledgeable about why these things might be failing: is there any legitimacy in assuming that, once a certain threshold is crossed, that one could rule out their particular unit as being affected by the potting compound issue? If I ran this thing for 500 or 1000 hours, and it didn't show signs of an error, could I reasonably assume this particular error won't crop up on my unit? (The number is obviously arbitrary and only an example, I am aware that we don't have a specific figure to shoot for here.)

I'm mostly just concerned about it doing something abnormal to my headphones, or my hearing for that matter.
I am not aware of any damage being caused by the A70 Pro headphones.
When it comes to loud noises, I am always very cautious about blaming a device because there are often several circumstances that can lead to it. You are always on the safe side if you stop the music and unplug the headphones before changing anything.

I can only estimate this based on my experience with the PA5; after 1000-1500 hours it is unlikely, and I have not had any defects with the encapsulated modules over 3000 hours.
 
Yes you can connect the A70Pro's XLR Line out to an external Amp.

As the A70Pro is an analog Preamp, its output voltage depends on the input voltage.

That means that you cannot set it to -6dB and assume that it'll output 4V.

It's highly recommended to purchase a basic $15 multimeter, as this will allow you to measure output voltages and Amp/Preamp gains yourself, in-situ.
okey dokey thank you for the info.

have decided to not use the a9ro with hifi.
it was more of a test.
you see i love this hobby iam not an expert just a novice.
my hifi is now using adi 2 dac fs and the e70 v. i switch between the 2
my comp setup is the a70 pro with e70 sabre and hd660s.

i did compare the adi and the e70 v playing diana krall, and Daft Punk. the adi sounds a little better, but i can tell you theres no much in it.
iam running hqplayer at 512 to a pi 5 naa
Sounds amazing.
I have lots of time on my hands now.
my partner of 35 yrs has developed alzheimer's and vascular dementia. Its Nightmare.

hifi is my escape.

any way than you for your advice
 
I am not aware of any damage being caused by the A70 Pro headphones.
When it comes to loud noises, I am always very cautious about blaming a device because there are often several circumstances that can lead to it. You are always on the safe side if you stop the music and unplug the headphones before changing anything.

I can only estimate this based on my experience with the PA5; after 1000-1500 hours it is unlikely, and I have not had any defects with the encapsulated modules over 3000 hours.

Okay, this gives me some peace of mind, even as I acknowledge the caveat for that figure. Thank you so much for your help, I think I will proceed with my plan and see how things go.
 
Earlier in this thread, in fact. Page 32 I think? There's a posted video that shows the popping and a follow up post from the same user mentioned that the driver wasn't the same afterward. There's a few other anecdotal reports that I had but I've sadly lost them amongst the hundreds of tabs I had open while researching into this.

Ahh, my bad about the volume control, I used the wrong terminology. I really meant "not potentiometer based" as that's the current issue I have with my 789.

And hmm, well, I may just bite the bullet and give it a shot. Here's a question for you, as you seem to be the most knowledgeable about why these things might be failing: is there any legitimacy in assuming that, once a certain threshold is crossed, that one could rule out their particular unit as being affected by the potting compound issue? If I ran this thing for 500 or 1000 hours, and it didn't show signs of an error, could I reasonably assume this particular error won't crop up on my unit? (The number is obviously arbitrary and only an example, I am aware that we don't have a specific figure to shoot for here.)

I'm mostly just concerned about it doing something abnormal to my headphones, or my hearing for that matter.

If it's anything like most other electronics, if it doesn't fail in the first minute, and then the first month, it's good to go for a long time
 
Does this amp somehow run out of juice when driving an HE-6? Like is there a way to measure the current and voltage to see if the power supply can’t keep up or dips somehow?
 
Does this amp somehow run out of juice when driving an HE-6? Like is there a way to measure the current and voltage to see if the power supply can’t keep up or dips somehow?

50 ohms? You can maximize voltage into 50 ohms.
ie. your ears will ring and the amp won't be stressed in the slightest.
edit: to add, a 50 ohm load will not stress the internal power supplies in the slightest. It's also a regulated supply so doesn't dip with loads (like unregulated supplies)
edit2: you could run two with a splitter at maximum output voltage and there would be no running out of power

Is that digicheck in your picture?
 
Does this amp somehow run out of juice when driving an HE-6? Like is there a way to measure the current and voltage to see if the power supply can’t keep up or dips somehow?
One can use an oscilloscope or calibrated ADC to measure voltages during playback, then infer current from the HE6 impedance and Ohm's law.

Though yeah I can't see the A70 Pro struggling whatsoever with a 50/64Ω load.

Do you have any issues with playback?
 
One can use an oscilloscope or calibrated ADC to measure voltages during playback, then infer current from the HE6 impedance and Ohm's law.

Though yeah I can't see the A70 Pro struggling whatsoever with a 50/64Ω load.

Do you have any issues with playback?
I am getting the HE6 tomorrow and was told by someone that the A70 cannot deliver the goods and need something like a Burson or Parasound to bring out the best from them. I’m not about to drop thousands on amps to find out. If the A70 can deliver 8W into 50 Ω (I assume) is there other amp factor that would not extract full performance from the headphones?
 
I am getting the HE6 tomorrow and was told by someone that the A70 cannot deliver the goods and need something like a Burson or Parasound to bring out the best from them. I’m not about to drop thousands on amps to find out. If the A70 can deliver 8W into 50 Ω (I assume) is there other amp factor that would not extract full performance from the headphones?

Oh wow 83.5dB/mW!
You'll be good with an A70 Pro.
1737597181825.png


You have to drop to 20 ohms before voltage doesn't reach 18RMS. You can run two HE6 in parallel with the A70 Pro!

6.48 watts for 1 pair
13 watts for 2

You should get 111dB from the HE6
 
Curious about things like damping factor
Damping factor is load impedance divided by output impedance.

The A70 Pro has 0.1Ω output impedance via SE out and 0.2Ω output impedance via Bal out.

If you know the load impedance, then calculating the damping factor is trivial.

and slew rate.
Slew rate is exceptionally high, otherwise the A70 Pro would not have such wide bandwidth:
Topping A70 Pro Headphone Amplifier Balanced frequency response Measurement.png

It looks like the A70 maintains voltage at 50 Ω which is good! What about current?
That the A70 Pro can maintain high voltage down to very low impedances, is a testament to its ability to supply loads of current.

If current was insufficient, then voltage when loaded would drop with it.

You can't have one without the other.
 
I appreciate all the info. It’s reassuring to get some science and engineering to balance against the audiophile woo.

I received the HE6 today and my signal chain is Windows > (usb) RME DAC (oratory EQ applied)> (balanced) A70pro > (xlr) HE6. With the DAC at -6 and the amp at -10 (low gain) it was fairly uncomfortable and I had to lower the volume. The headphones sounded good! I didn’t play with high gain yet.
 
I appreciate all the info. It’s reassuring to get some science and engineering to balance against the audiophile woo.

I received the HE6 today and my signal chain is Windows > (usb) RME DAC (oratory EQ applied)> (balanced) A70pro > (xlr) HE6. With the DAC at -6 and the amp at -10 (low gain) it was fairly uncomfortable and I had to lower the volume. The headphones sounded good! I didn’t play with high gain yet.

Which RME DAC are you using? I don't think you need to be at -6dB, the A70 Pro should be good for input up to a bit over 10V.

Glad to hear it's working well/sounding good!

edit: or is the -6dB to account for the EQ you applied?
 
I appreciate all the info. It’s reassuring to get some science and engineering to balance against the audiophile woo.

I received the HE6 today and my signal chain is Windows > (usb) RME DAC (oratory EQ applied)> (balanced) A70pro > (xlr) HE6. With the DAC at -6 and the amp at -10 (low gain) it was fairly uncomfortable and I had to lower the volume. The headphones sounded good! I didn’t play with high gain yet.
Amir measured the sensitivity of the HE-6 as 1.25 V being required for 94 dB SPL. If the RME DAC was set to output 19 dBu at full volume, the peak SPL would have been around 94 - 20*log10(1.25) + 10*log10(0.6) + 19-6 + 6-10 + 10*log10(2) = 101.85 dB SPL. That can be pretty loud depending on the music.

The RME already produces 7.8 V RMS at 50 Ohm, which gives a peak SPL of 94-20*log10(1.25) + 20*log10(7.8) + 10*log10(2) = 112.91 dB SPL. The A70 Pro produces 18 V RMS at 50 Ohm, which gives a peak SPL of 94-20*log10(1.25) + 20*log10(18) + 10*log10(2) = 120.18 dB SPL.
 
Amir measured the sensitivity of the HE-6 as 1.25 V being required for 94 dB SPL. If the RME DAC was set to output 19 dBu at full volume, the peak SPL would have been around 94 - 20*log10(1.25) + 10*log10(0.6) + 19-6 + 6-10 + 10*log10(2) = 101.85 dB SPL. That can be pretty loud depending on the music.

The RME already produces 7.8 V RMS at 50 Ohm, which gives a peak SPL of 94-20*log10(1.25) + 20*log10(7.8) + 10*log10(2) = 112.91 dB SPL. The A70 Pro produces 18 V RMS at 50 Ohm, which gives a peak SPL of 94-20*log10(1.25) + 20*log10(18) + 10*log10(2) = 120.18 dB SPL.

Amir's measurement is that much more efficient than 83.5dB/mW?
If I were the manufacturer I wouldn't be advertising such a low number - I'm sure many people have passed over that headphone for its sensitivity.
I'm actually interested in it now lol
 
Amir's measurement is that much more efficient than 83.5dB/mW?
If I were the manufacturer I wouldn't be advertising such a low number - I'm sure many people have passed over that headphone for its sensitivity.
I'm actually interested in it now lol
Amir measured both the HE6 and HE6se V1 at 79dB/mW, so even lower than advertised.

Sound Stage Network, another measurement source, measured the HE6se at 80dB/mW.
 
Which RME DAC are you using? I don't think you need to be at -6dB, the A70 Pro should be good for input up to a bit over 10V.

Glad to hear it's working well/sounding good!

edit: or is the -6dB to account for the EQ you applied?
I have the DAC not the Pro. I usually run it at -13 but turned it up close to 0 and it was showing OVR on some tracks so I backed it off.
 
Another question. I forget the exact numbers but let’s say that the A70 low gain is 6 and high is 19. Should the volume and sound quality be the same if the amp is at -10 on low gain and -29 on high?
 
Another question. I forget the exact numbers but let’s say that the A70 low gain is 6 and high is 19. Should the volume and sound quality be the same if the amp is at -10 on low gain and -29 on high?
Apart from higher noise, it should be the same.
 
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