[mgoodman]

@mgoodman

Thanks for all the responses ! So, at this time, Hifi-M8 V2 provides 1.6 W per channel @ 75 ohm. With this new dedicated amp, it hovers about 2 W per channel, based on battery constraints. Why don't we have a larger capacity battery to handle this extra power driven battery consumption ?

What volume level is the battery tested at ? If you say 80 dBA average (which occurs at half the volume dial), low gain and battery only lasts for 4-5 hours, could be quite concerning. It is not just about the loudness, but how certain regions in the audio spectrum (bass specifically requires lot more power because impedance curve is non-linear) are being properly excited with enough headroom.

ATH-R70X is classic case for this.

We are running a variety of tests under many conditions. It's early to make assumptions. Battery is quite large but so is the output power. And at some point any battery will be depleted. The math is simple.

The real issue is the multi-parametric optimization. That's to say, you have-real world product size, real-world battery, real-world cans and real world music. Also, real world people... Add to that the amps and power supplies, which are not 100% efficient. Given the above, the goal is to choose the best customer experience.

We understand the engineering variables. At CAN JAM we plan to understand the human variables, i.e., musics, headphones, loudness preferences, etc. Like how many people actually get on a bike wearing $5k cans. After that, we should be able to strike an educated balance.

 

[ssriram2791]

We are running a variety of tests under many conditions. It's early to make assumptions. Battery is quite large but so is the output power. And at some point any battery will be depleted. The math is simple.

The real issue is the multi-parametric optimization. That's to say, you have-real world product size, real-world battery, real-world cans and real world music. Also, real world people... Add to that the amps and power supplies, which are not 100% efficient. Given the above, the goal is to choose the best customer experience.

We understand the engineering variables. At CAN JAM we plan to understand the human variables, i.e., musics, headphones, loudness preferences, etc. Like how many people actually get on a bike wearing $5k cans. After that, we should be able to strike an educated balance.

If you get a chance, could you post your observations on what the customer expectations look like after the Canjam meet this weekend ?

I am sure Canjam would be a place where you would meet experienced audiophiles and hopefully we get to know what they perceive as acceptable portable amp performance.

 

[mgoodman]

I hope Ampersand will work on external power supply and not only battery, though I know that some prefer 100% battery powered amp or DAC (Sony DMP-Z1).
It sounds strange as there seems to be only a little 5V 2.4A USB-C input on Ampersand, so I doubt it works from the external power supply/bank without passing through the battery.

It works like this:

- If you are on battery, the product takes power from the battery.
- If you are plugged into a beefy charger or power bank (12W is beefy for this conversation) then it runs entirely from the external power and doesn't engage the battery.
- If you are plugged into a dinky charger that doesn't provide the needed juice, then the system will automatically engage the battery to add the remaining needed current. In this case the battery will go down, but slower.

 

[mgoodman]

If you get a chance, could you post your observations on what the customer expectations look like after the Canjam meet this weekend ?

I am sure Canjam would be a place where you would meet experienced audiophiles and hopefully we get to know what they perceive as acceptable portable amp performance.

We don't plan to post our marketing research results, for obvious reasons.

But we will strive to deliver the product that manages to please the most while offending the least amount of people. That seems to be the best strategy when it comes to these optimizations

 

[mgoodman]

Balanced XLR is unique feature that makes Centrance stand out from others. Kudos to them for that and hence makes me interested to see more power with their dedicated amp.

Many thanks. XLR as well as the 4.4mm jack will be available on Ampersand. Also USB-C. We are catching up with the times

 

[mgoodman]

I view Centrance Ampersand as a portable equivalent of desktop Class A system, which I can carry around and hence making sure I get as much power out of it (R70X can sing if properly driven - though people like to call it neutral)

The trick is to determine what level of output voltage represents "loud enough" for the vast majority of folk and across the vast majority of headphones. We know that HiFi-M8 is just about on the edge for some people. So it's reasonable to say that we don't need to double what it can do, as that might be overkill. So far we are hovering at about 1.5x in our assumptions. And again, these are assumptions for now. The amp can do more, but we plan to pull it back in favor of the battery life and not ripping up expensive cans

 

[ssriram2791]

The trick is to determine what level of output voltage represents "loud enough" for the vast majority of folk and across the vast majority of headphones. We know that HiFi-M8 is just about on the edge for some people. So it's reasonable to say that we don't need to double what it can do, as that might be overkill. So far we are hovering at about 1.5x in our assumptions. And again, these are assumptions for now. The amp can do more, but we plan to pull it back in favor of the battery life and not ripping up expensive cans

Based on the DAPs used in my signature, I know few of them that can provide 4 Vrms in SE and 8 Vrms in balanced. Those ratings are at 300 ohms.

Taking HD800S as an example

1 Vrms - 102 dB
2 Vrms- 108 dB
4 Vrms - 114 dB
8 Vrms - 120 dB

Do I hear music at 8 Vrms ? NO !!!!!

Most likely people would end up using pre-amp gain (software gain in UAPP/Equalizer APO, hardware gain in Amplifier) and EQ (for brighter/hot treble cans) to reduce the volume while increasing the voltage through amplifiers. This should help drive the headphones much better.

Centrance Hifi-M8 V2 produces about 6.1 Vrms. I hope this is atleast increased to 8-10 Vrms in AMPERSAND.

I would be pretty interested to see where the voltage rating for XLR/4.4 mm outputs land.

 

[mgoodman]

Based on the DAPs used in my signature, I know few of them that can provide 4 Vrms in SE and 8 Vrms in balanced. Those ratings are at 300 ohms.

Taking HD800S as an example

1 Vrms - 102 dB
2 Vrms- 108 dB
4 Vrms - 114 dB
8 Vrms - 120 dB

Do I hear music at 8 Vrms ? NO !!!!!

Most likely people would end up using pre-amp gain (software gain in UAPP/Equalizer APO, hardware gain in Amplifier) and EQ (for brighter/hot treble cans) to reduce the volume while increasing the voltage through amplifiers. This should help drive the headphones much better.

Centrance Hifi-M8 V2 produces about 6.1 Vrms. I hope this is atleast increased to 8-10 Vrms in AMPERSAND.

I would be pretty interested to see where the voltage rating for XLR/4.4 mm outputs land.

Awesome info, thank you! Passing on to the internal team.

 

[mgoodman]

Centrance Hifi-M8 V2 produces about 6.1 Vrms. I hope this is atleast increased to 8-10 Vrms in AMPERSAND.

So looks like we are there already (and possibly more). But this depends on the headphone impedance. Which models are you referring to specifically that you would like to see 8...10 Vrms with?

 

[ssriram2791]

So looks like we are there already (and possibly more). But this depends on the headphone impedance. Which models are you referring to specifically that you would like to see 8...10 Vrms with?

I did a quick sound level meter based assessment for the following headphones (1 particular track with dynamic range of 17 dBA)

Centrance Hifi-M8 V2 (6.1 Vrms)

Audio Technica ATH-R70X (470 ohms 102 dB/V) - 100% Volume Low Gain - Peak 89.0 dBA
Audio Technica ATH-R70X (470 ohms 102 dB/V) - 100% Volume High Gain - Peak 108.4 dBA
Sennheiser HD800S (300 ohms 102 dB/V) - 100% Volume Low Gain - Peak 93.4 dBA
Sennheiser HD800S (300 ohms 102 dB/V) - 100% Volume High Gain - Peak 114.0 dBA
Heddphone V2 (42 ohms 101 dB/V) - 100% Volume Low Gain - Peak 85.5 dBA
Heddphone V2 (42 ohms 101 dB/V) - 100% Volume High Gain - Peak 105.5 dBA

I have Focal Clear and Hifiman Ananda, but those can run fine because of low impedance and high sensitivity. The above 3 headphones (especially R70x and Heddphone are not having lot of headroom to be honest). I think HD800S is fine compared to those 2.

Of the DAPs in my possession, Ibasso DX220 Max (8.4 Vrms) and Cayin N6ii+Cayin C9 stack (8.2 Vrms) can run atleast 4-6 dBA more than Hifi-M8 V2 at present for all these headphones.

I love the XLR output and sound quality coming is awesome with Centrance Hifi-M8 V2 and hence I wish about 4-6 dBA more headroom when stacked with AMPERSAND, so that I can run them with more power to properly drive bass region (<250 Hz) frequencies.

As you noted with ATH-R70X impedance and phase vs frequency chart, the impedance doubles in the bass region and with less power, the bass quality is not great. It seems to be the case with every open back headphones (Impedance being double of nominal value at frequencies below 250 Hz).

6dBA increase from Hifi-M8 V2 equates to about 12.2 Vrms , 4 dBA increase equates to 9.7 Vrms.

10 Vrms is great. 12 Vrms would be exceptional. Sorry for long post.

 

[newworld666]

10 Vrms is great. 12 Vrms would be exceptional. Sorry for long post.

This should be a nice target (assuming THD stays at a low level)... I already own the Kann Alpha which is sold for 12 V but unusable over 9V due to monstrous THD.

I have great hopes, too with Ampersand to be at Less Bx2+ SQ level but with a much better form factor, some more battery life => it would be the perfect add-on for my WM1A or M8V2... it will keep me going to give a try to the future Fiio M17, as it would be comfortable to use a really pocketable Sony WM1A with some IEM in the street and add the Ampersand for trips with a closed Stealth/Ed15 Veritas when sitting in train/plane or at hotel.

 

[mgoodman]

I did a quick sound level meter based assessment for the following headphones (1 particular track with dynamic range of 17 dBA)

Centrance Hifi-M8 V2 (6.1 Vrms)

Audio Technica ATH-R70X (470 ohms 102 dB/V) - 100% Volume Low Gain - Peak 89.0 dBA
Audio Technica ATH-R70X (470 ohms 102 dB/V) - 100% Volume High Gain - Peak 108.4 dBA
Sennheiser HD800S (300 ohms 102 dB/V) - 100% Volume Low Gain - Peak 93.4 dBA
Sennheiser HD800S (300 ohms 102 dB/V) - 100% Volume High Gain - Peak 114.0 dBA
Heddphone V2 (42 ohms 101 dB/V) - 100% Volume Low Gain - Peak 85.5 dBA
Heddphone V2 (42 ohms 101 dB/V) - 100% Volume High Gain - Peak 105.5 dBA

I have Focal Clear and Hifiman Ananda, but those can run fine because of low impedance and high sensitivity. The above 3 headphones (especially R70x and Heddphone are not having lot of headroom to be honest). I think HD800S is fine compared to those 2.

Of the DAPs in my possession, Ibasso DX220 Max (8.4 Vrms) and Cayin N6ii+Cayin C9 stack (8.2 Vrms) can run atleast 4-6 dBA more than Hifi-M8 V2 at present for all these headphones.

I love the XLR output and sound quality coming is awesome with Centrance Hifi-M8 V2 and hence I wish about 4-6 dBA more headroom when stacked with AMPERSAND, so that I can run them with more power to properly drive bass region (<250 Hz) frequencies.

As you noted with ATH-R70X impedance and phase vs frequency chart, the impedance doubles in the bass region and with less power, the bass quality is not great. It seems to be the case with every open back headphones (Impedance being double of nominal value at frequencies below 250 Hz).

6dBA increase from Hifi-M8 V2 equates to about 12.2 Vrms , 4 dBA increase equates to 9.7 Vrms.

10 Vrms is great. 12 Vrms would be exceptional. Sorry for long post.

Thank you, this is very valuable. Have passed along to the team, we are chewing on this. Meantime, demos and show impressions coming soon from CANJAM!

 

[ssriram2791]

Thank you, this is very valuable. Have passed along to the team, we are chewing on this. Meantime, demos and show impressions coming soon from CANJAM!

My wallet is waiting for the final specs confirmation... There would be nothing sweet like walking around the home with open back headphone connected to desktop level XLR outputs in my pocket (Pinnacle of Portability)

 

[ChrisLN]

Please don’t make the Ampersand any less powerful than the initial design goals. The only reason I preordered this instead of buying the M8V2 or any other portable amps is because of the initially quoted power output.

 

[ssriram2791]

Thank you, this is very valuable. Have passed along to the team, we are chewing on this. Meantime, demos and show impressions coming soon from CANJAM!

@mgoodman

Hope you had a great time at Canjam with the demos and the seminars. Would like to know what impressions were shared by users who tested AMPERSAND at your booth (there has been few on the Canjam impressions thread, but there is less clarity) . A mention about headphones that were used in conjunction with the AMP would also be great.

Finally, we are eager to know where the specs for XLR and 4.4 mm outputs are going to land. Would it be published by end of October, as the pre-orders start rolling out ?