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HM-901 - Page 162

post #2416 of 3194
Quote:
Originally Posted by kkcc View Post


Yes the 802 share ALL accessories and cables with the 901 and their form factor is identical. Will use the same UI and firmware also.

The key differences are:
- Dual wm8740 DAC instead of dual ess9018 on 901
- normal POT vs the high quality stepped attenuator on 901 (some may actually prefer this over the stepped approach for usability, though sound quality suffers)
- grayish blue (or bluish gray) vs black on the 901

Sound quality may not suffer due to the POT (though I'm sure the 901 is better for other reasons) but channel tracking certainly should and with the gain of some of the output cards, more so. Much of the best sounding kit in this world still use POTs. Tracking is a form of quality so I'm not disagreeing, just saying that there's nothing sonically lacking in a good pot compared to discreet resistor one other than tracking. 

post #2417 of 3194
Quote:
Originally Posted by goodvibes View Post

Sound quality may not suffer due to the POT (though I'm sure the 901 is better for other reasons) but channel tracking certainly should and with the gain of some of the output cards, more so. Much of the best sounding kit in this world still use POTs. Tracking is a form of quality so I'm not disagreeing, just saying that there's nothing sonically lacking in a good pot compared to discreet resistor one other than tracking. 

Yup this is correct. Good POTs won't cause any degradation and they are also very expensive components.

I should clarify that this comment is only specific to the 901 v 802 where the "normal POT" is one of the first things Fang mentioned as a key differentiation and also a key reason why 901 is much more costly to make for them (and thus priced much higher). I would rather they implement a digital volume control using the wm8740 than an analog POT but probably it is more economical to retain most of the same circuitry with the POT.
post #2418 of 3194
Quote:
Originally Posted by LECW View Post

I read in some Chinese blog that the initial portion was some what cut off. Could someone kindly confirm with this new firmware and may I also does this new firmware sound signature!

Thanks man.

The fading in/missing first seconds issue is fixed for me in 1.082. smily_headphones1.gif
post #2419 of 3194

In my short experience - the missing second or two in the beginning of a new-selected track is MOSTLY fixed, but unfortunately not completely. I also often hear a little click when a new-selected track is played, and this happens only when the track is played from the very beginning. So - it seems to be difficult for HiFiMan to fix, since this has also been issues with my HM-602 (sold long ago) and HM-801.

post #2420 of 3194
Quote:
Originally Posted by kkcc View Post

Yup this is correct. Good POTs won't cause any degradation and they are also very expensive components.

I should clarify that this comment is only specific to the 901 v 802 where the "normal POT" is one of the first things Fang mentioned as a key differentiation and also a key reason why 901 is much more costly to make for them (and thus priced much higher). I would rather they implement a digital volume control using the wm8740 than an analog POT but probably it is more economical to retain most of the same circuitry with the POT.
A digital volumen control that won't drop bits will need upsampling and processing algorithmically the signal. It won't be cheaper or battery friendly cos all the data will be upsampled and processed constantly, this means ALL the time. The POT is a better solution. The main problem with the POT is keep the same volume for both channel, with the usage those tends to unbalanced even the expensive ones. With the step attenuator you're sure that at every step the volume is the same in both channels. One of the main reason that I choose the HM901 was the step attenuator in the volume.
post #2421 of 3194
Thks pal
Quote:
Originally Posted by kkcc View Post

The fading in/missing first seconds issue is fixed for me in 1.082. smily_headphones1.gif
post #2422 of 3194
Quote:
Originally Posted by fermelom View Post

A digital volumen control that won't drop bits will need upsampling and processing algorithmically the signal. It won't be cheaper or battery friendly cos all the data will be upsampled and processed constantly, this means ALL the time. The POT is a better solution. The main problem with the POT is keep the same volume for both channel, with the usage those tends to unbalanced even the expensive ones. With the step attenuator you're sure that at every step the volume is the same in both channels. One of the main reason that I choose the HM901 was the step attenuator in the volume.

The wm8740 has built in digital volume control and can be accessed via firmware directly, and is the approach ak100/120 and dx50 are taking. No extra circuitry or processing other than the DAC chip itself.
post #2423 of 3194
Hello guys, need some advice here. Some people hqve reported that the iem card sounds better with iems, or at least low impedance ones. I have no issue with the balanced card sound, but the volume steps are really an issue. It is often too loud or not loud enough, between 1 and 2.
Would switching to iem card solve this? Would the steps be much finer? What about the Minibox? Another thing is that my go to iem is the SE5 which has 135 ohms of impedance. Which card is theoretically more adapted?
post #2424 of 3194
I haven't heard the IEM amp card, but from a theoretical standpoint (for use with IEMs and other sensitive headphones) the only "drawback" compared to the Balanced amp is that it's single ended.

Since the IEM card has much less power the max volume will be much lower and this means more useful steps on the volume control.

Output impedance on both amp cards is less than 1 Ohm, which makes them equally good for low impedance IEMs and headphones.
post #2425 of 3194
Quote:
Originally Posted by kkcc View Post

The wm8740 has built in digital volume control and can be accessed via firmware directly, and is the approach ak100/120 and dx50 are taking. No extra circuitry or processing other than the DAC chip itself.
To be honest I didn't knew about the integrated digital volumen control in the chip, but what I tried to say it's that only a control that upsample and process the signal won't deteriorate the SQ. Take a look to this explanation about the mods to the ak120: http://redwineaudio.com/mods/rwak120-s specially the section about the volume control.
post #2426 of 3194
The volume steps with the 901 balanced card for my HifiMan RE-400s and Shure SE530s with balanced card are too large and it's too loud for me after I go past 2 on the volume level with low gain. I also tried the balanced RE-600s with the same result: volume for me too loud past 2 low gain. So I bought the iem card hoping it would solve the volume problem. The iem card solves the volume problem sort of. Now I can listen to the RE400s and Shure SE530s at volume level 3 low gain. And my AKG 702 Annie is at volume 6 high gain, my Edition 8 at volume 4.7 low gain, my Denon AH-D2000 at volume 4.7 low gain. Since I could not detect a sound difference between the balanced card and the iem card I decided to keep the iem card and not return it (I admit it was hard to change the card out and then listen again to the same song with the same headphones single ended only, so take my opinion re sound quality for what it's worth as YMMV). Also my Sennheiser HD580s single ended and HiFiMan HE-500s single ended could not be driven to satisfactory levels by the iem card. So for those cans I use the balanced card. What to do? While I love the iem card sound quality, it doesn't quite solve the volume step issue as much as I'd like. It's just enough for me but I do wish I could listen to my iem's at volume level 4 or 5 or even 6. Again, YMMV. If you can find a shop or HiFiMan that will let you try the iem card and return it if you don't like it that would be best IMO. Hope I've been helpful.
post #2427 of 3194
Thanks for the opinion guys. Only thing stopping me is that I just got a balanced cable for my top iems....
But why do you say it only partly solves the volume issue for iems? Is it still not fine enough?
post #2428 of 3194
Quote:
Originally Posted by Mimouille View Post

Thanks for the opinion guys. Only thing stopping me is that I just got a balanced cable for my top iems....
But why do you say it only partly solves the volume issue for iems? Is it still not fine enough?

I have the stock, balanced and iem amp cards: the iem card has a sig which is very refined, excellent soundstage and detailed. It blows me away on the fitears, whether 333, 334 or 435. It is also well suited for the AKG K3003.

As for the volume issue, it does give you better control than on the balanced card. Not perfect but certainly less frustrating than the balanced amp card, where the choice is between straining to hear the details and being deafened...
post #2429 of 3194
Quote:
Originally Posted by Kiats View Post

I have the stock, balanced and iem amp cards: the iem card has a sig which is very refined, excellent soundstage and detailed. It blows me away on the fitears, whether 333, 334 or 435. It is also well suited for the AKG K3003.

As for the volume issue, it does give you better control than on the balanced card. Not perfect but certainly less frustrating than the balanced amp card, where the choice is between straining to hear the details and being deafened...
Thanks a lot for the answer! And so are there any drawbacks versus the balanced card if I only use iems? And have you tried the Minibox?
post #2430 of 3194
Quote:
Originally Posted by kkcc View Post
 

 

Congratz in scoring one of these gems.  Waiting for your impression.

That DIY card with th900 is absolutely fantastic.....seriously good, powerful, impactful 

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