[Sniping]

First off, been a long time since I posted on Head-Fi and I'm back because I wanted to say that the Deva Pro is great. It's truly what I consider to be practical hifi. There's a lot of good that I can go on about but really I wanted to talk about my main points of improvement for the headphone and I wanted to see what people thought about it. I also sent an email to Hifiman to let them know about my thoughts. It mostly surrounds the implementation and UI of the Bluetooth interface.

My thoughts are that all the Bluemini R2R cues are way too loud. The on, off, connected, and low battery sounds not only need to be a lot quieter, but need less obstructive tones/chimes. Right now it's so loud that I don't even put my headphones on until the power on and connected cues are done playing because they're loud and unpleasant. I would say that this doesn't compare to the low battery sound, which is so jarring and loud that it's pretty much impossible to listen to anything on low battery because it's so startling and annoying to hear the sound repeatedly.

Another great feature to see in the Bluemini R2R would be the support of AptX low latency, which would make the headphone a perfect headset for all purposes including gaming.

I think those change would make the headphone a really solid and feature rich product for the price point, like exceptionally good of a product. As it stands, I'm still really happy with all that you get for the money, because frankly it's a lot already. My listening time higher because the Deva Pro is so easy to just use anywhere and anytime, with any device. I think that if we see these changes in the future it'll be a killer product.

 

[Sniping]

While charging my Bluemini, I have noticed that after a couple hours the red will change to green. Sometimes if I leave the Bluemini plugged into the USB port, the LED will change back to red for a while before returning to green. I'm not sure what is going on there. If I put an ammeter in series with the USB cable I see that the current drops to 0mA when the green LED comes on. I haven't yet determined what happens to cause the LED to change back to RED. I haven't had the ammeter dongle in-line when that happens, but will do so from this point forward in an attempt to know what is happening. I would only assume that if the LED is RED, there will be current flow into the battery.

I would assume it's protection from overcharging the bluemini. Your smart phone and laptop probably does something similar where it'll drain down to 99% occasionally after getting fully charged, and then top back up to 100%.

 

[ultrarunner2018]

I tend to be OCD when it comes to batteries, so maybe I'm over-thinking.
In the past, I learned that to get the longest life (in terms of capacity and recharge cycles) of a lithium battery, one should never allow them to run down below 20%, but optimal is between 50-85%. The science has probably changed since those days, but I try to keep my phone between 50-85%. That's difficult to do with the Bluemini, since it doesn't have its own battery level meter, and what I get on my Galaxy A51 Android 11 phone is useless; it will read 100% when first charged, drop to 80% and then after that it remains at 80% for a while before dropping to 60%. After 60%, the battery drops to 20% in a relatively short time. The battery indicator is anything but linear.
So I'm just getting into the habit of recharging it to 100% after each session. Whether or not this practice will reduce the useful life of the battery remains to be seen - but I expect that by the time the battery in the Bluemini loses its capacity, I will simply replace the Bluemini. I would assume that HiFiMAN would offer this replacement at a reduced cost (if out of warranty), but at least the headphones themselves aren't affected.

I agree that the low-battery chime is far too loud. Another thing I would like to see in the next Bluemini rev is the ability to turn off the LED indicator. It can be distracting in a dark environment.

All of the above aside, I am very happy with my Deva Pro's. It's hard for me to notice any degradation in quality when used with the Bluemini compared to wired. I cannot say that about any of my other BT devices. Then, I don't have much to compare to. My other BT devices are JBL/UA Sport Train on-ear and a pair of Jabra Elite Active 75t IEM's.

 

[tinyman392]

I tend to be OCD when it comes to batteries, so maybe I'm over-thinking.
In the past, I learned that to get the longest life (in terms of capacity and recharge cycles) of a lithium battery, one should never allow them to run down below 20%, but optimal is between 50-85%. The science has probably changed since those days, but I try to keep my phone between 50-85%. That's difficult to do with the Bluemini, since it doesn't have its own battery level meter, and what I get on my Galaxy A51 Android 11 phone is useless; it will read 100% when first charged, drop to 80% and then after that it remains at 80% for a while before dropping to 60%. After 60%, the battery drops to 20% in a relatively short time. The battery indicator is anything but linear.
So I'm just getting into the habit of recharging it to 100% after each session. Whether or not this practice will reduce the useful life of the battery remains to be seen - but I expect that by the time the battery in the Bluemini loses its capacity, I will simply replace the Bluemini. I would assume that HiFiMAN would offer this replacement at a reduced cost (if out of warranty), but at least the headphones themselves aren't affected.

I agree that the low-battery chime is far too loud. Another thing I would like to see in the next Bluemini rev is the ability to turn off the LED indicator. It can be distracting in a dark environment.

All of the above aside, I am very happy with my Deva Pro's. It's hard for me to notice any degradation in quality when used with the Bluemini compared to wired. I cannot say that about any of my other BT devices. Then, I don't have much to compare to. My other BT devices are JBL/UA Sport Train on-ear and a pair of Jabra Elite Active 75t IEM's.

There typically isn't an issue with letting the batteries discharge to "0%." For most modern batteries, 0% isn't 0% as if you let a battery completely drain, it will become a dead battery; it needs a little charge to actually be able to recharge. That said, letting it drop below 20% isn't an issue. Every once in a while, it can be useful for it to discharge close to empty to allow it to re-gauge the batteries discharge scale (if you're experiencing abnormally fast discharge or inaccurate battery readings), though I'm not sure how true this actually is.

That said, the life of the battery is typically based on the total number of discharge cycles it has gone through. Most batteries can handle 300-500 discharge cycles before they are considered depleted. So charging a battery from 80-100 5x would be 1 full discharge cycle. Charging a battery from 20% to 100% would use 0.8 discharge cycles. I'm not sure how much a battery replacement would cost through HiFiMan nor how said procedure would be done (where the BluMini needs to be sent) if the service is available.

 

[ultrarunner2018]

I would expect that when the Bluemini's battery loses more than 1/2 of its capacity it should be replaced. I would assume that HiFiMAN would simply replace the Bluemini rather than attempt to replace the battery.

 

[tinyman392]

I would expect that when the Bluemini's battery loses more than 1/2 of its capacity it should be replaced. I would assume that HiFiMAN would simply replace the Bluemini rather than attempt to replace the battery.

It depends on the design and how accessible the battery is.

 

[MisterMudd]

It depends on the design and how accessible the battery is.

I have had the OG Deva for a year now with no problems, but I wish HiFiMan would sell the blue mini separately. I would gladly buy another as backup.

 

[HipHopScribe]

I have had the OG Deva for a year now with no problems, but I wish HiFiMan would sell the blue mini separately. I would gladly buy another as backup.

Have you emailed them to ask?

 

[rev92]

Yea, definitely contact HiFiman and see if they can seel it separately, it's a great little thing

 

[CrackerJibbs]

So after owning these for a month, my overall feeling is one of disappointment.

I love the sound and the convenience of these headphones, but the frustrating useability issues mean I'm going to be sending mine back. The extremely loud notifications and the static in the left earcup, and to a lesser exetent the super bright flashing light and the lack of volume controls, are unacceptable to me for a $500 CAD headphone.

I emailed Hifiman to ask about a firmware update to at least correct the notification sounds and they said they passed my suggestion along to their engineers, so hopefully it all gets worked out at some point. If that happens, I'll pick these up again.

 

[amorrish]

No, although I did have a occasional clicking from left earcup when first had them but it disappeared within 2 days and so far has not returned, the blue mini is a little marvel, I patched up a cable so I can drive other headphones with it just to try, my Sundara's 2020/21 sound very enjoyable and completely driven with it as do mu 6xx's so low impedence low sensitivity and high impedence 100+ Sensitive headphines driven no problem.

 

[ultrarunner2018]

Maybe I'll buy an adapter so I can try the Bluemini with my Senn HD600's. After all, it's only a couple bucks for such an adapter - or I could build it myself.
The only question is whether the Bluemini - which was designed for the 18 ohm Deva Pro - will drive the 300 ohm HD600's.
By ohm's law, a headphone with a higher Z (300 vs 18 ohms) will require a higher voltage but lower current to properly drive. I guess it's worth a try - if only for curiosity.

 

[Denosha]

I got my bluemini replaced at the local dealer yesterday. New one is perfect and doesn't have the same weird noise/static coming from the left earcup. The staff thinks it might be some sort of grounding issue on my original bluemini, but anyway they will send it back to Hifiman to check.

 

[Nick24JJ]

Just ordered them on Amazon UK, I will have them by Friday

 

[Nick24JJ]

Hello again, I've received these today. Just out of curiosity, how many hours do they need to burn in? @Ichos , what do you think?