[Hififox]

I found one more question that my phono amplifier output voltage is 300mV at 1kHz, but the input sensitivity is 200mVrms, so could I connect my phono amplifier with hd-dac1 by using a RCA to 3.5mm cable directly? BTW my phono amplifier is pro-ject phono box.
Thank you.

 

[2leftears]

Hi, I'm interesting in HD-DAC1, but I found it only has 3.5mm line input. I own a turntable that I like to connect my phono amplifier with RCA line output to HD-DAC1 amplifier stage, so I like to know whether the rca to 3.5mm cable distorts the quality or not?

Thank you.

I found one more question that my phono amplifier output voltage is 300mV at 1kHz, but the input sensitivity is 200mVrms, so could I connect my phono amplifier with hd-dac1 by using a RCA to 3.5mm cable directly? BTW my phono amplifier is pro-ject phono box.
Thank you.

EDITED 10 Feb 2015: got my dB wrong - needed to be doubled :rolleyes:


Please note that the 3.5mm analogue input does not feed directly into the amp section. This qobuz review shows that it first goes through an active low pass filter based around the NJM-2115, and is then digitised at 24bit 96kHz by a Burr Brown PCM9211. Hence how it will deal with a 300mV input depends on how the Marantz engineers have designed it. Ideally the active filter should be driven into soft-clipping before the ADC starts clipping.

I would imagine that you might need to attenuate your 300mV output a little bit though, -6dB might be enough (= half amplitude). It also depends a bit on what the 300mV output level of your amp really means. Is it 300mV peak, RMS etc.? To be on the save side you might want to attenuate -12dB or so (= 1/4 amplitude).

Bear in mind that the PCM9211 ADC gives you 24bits of dynamic range to play with, so you can probably afford to be a bit conservative with the attenuation. Do keep a eye (ear) on the noise levels though.

If I find some time I will try to o-scope a function-generator signal through the HD-DAC1 to see how the analogue input clips, and at what levels.

In any case, I don't expect the use of an RCA to 3.5mm cable to affect the sound quality much at all, provided you buy a good and short one, or make one yourself.

 

[Hififox]

Please note that the 3.5mm analogue input does not feed directly into the amp section. This qobuz review shows that it first goes through an active low pass filter based around the NJM-2115, and is then digitised at 24bit 96kHz by a Burr Brown PCM9211. Hence how it will deal with a 300mV input depends on how the Marantz engineers have designed it. Ideally the active filter should be driven into soft-clipping before the ADC starts clipping.

I would imagine that you might need to attenuate your 300mV output a little bit though, -3dB might be enough (= half amplitude). It also depends a bit on what the 300mV output level of your amp really means. Is it 300mV peak, RMS etc.? To be on the save side you might want to attenuate -6dB or so (= 1/4 amplitude).

Bear in mind that the PCM9211 ADC gives you 24bits of dynamic range to play with, so you can probably afford to be a bit conservative with the attenuation. Do keep a eye (ear) on the noise levels though.

If I find some time I will try to o-scope a function-generator signal through the HD-DAC1 to see how the analogue input clips, and at what levels.

In any case, I don't expect the use of an RCA to 3.5mm cable to affect the sound quality much at all, provided you buy a good and short one, or make one yourself.

Thank you so much! That's really helpful. I'm not sure it's 300mV p-p or rms valve, it doesn't shown in the documentation. I will try to check by myself later.

 

[frankrondaniel]

I recently received a replacement HD-DAC1 unit after the USB circuitry died on my first unit.  USB's fine so far but I'm noticing a hum that I don't recall hearing on my first unit.  The hum is noticeable when no music is playing and increases with the gain setting.  I'm curious if other owners are experiencing the same.

 

[kazcou]

  I recently received a replacement HD-DAC1 unit after the USB circuitry died on my first unit.  USB's fine so far but I'm noticing a hum that I don't recall hearing on my first unit.  The hum is noticeable when no music is playing and increases with the gain setting.  I'm curious if other owners are experiencing the same.

No hum on mine.
Maybe a usb noise problem ?
Can you check another input ?

 

[frankrondaniel]

 
No hum on mine.
Maybe a usb noise problem ?
Can you check another input ?

 
It looks like it's unrelated to USB - I get the hum using coax (out of Fiio X3) as well.  In each case the hum doesn't occur until it locks on to a sampling rate for the first time.  Did a quick Google search - found hits on stevehoffman, diyaudio sites reporting hum as well.  I may have received another defective unit.

 

[JamieMcC]

  I recently received a replacement HD-DAC1 unit after the USB circuitry died on my first unit.  USB's fine so far but I'm noticing a hum that I don't recall hearing on my first unit.  The hum is noticeable when no music is playing and increases with the gain setting.  I'm curious if other owners are experiencing the same.

Are you using different more sensitive lower z cans?

 

[frankrondaniel]

 
Are you using different more sensitive lower z cans?

 
Using the same as with prior unit - Senn HD800.

 

[2leftears]

  I recently received a replacement HD-DAC1 unit after the USB circuitry died on my first unit.  USB's fine so far but I'm noticing a hum that I don't recall hearing on my first unit.  The hum is noticeable when no music is playing and increases with the gain setting.  I'm curious if other owners are experiencing the same.

I notice you are in the U.S.  If you are using a 2-pin plug on the power cord, have you tried flipping it around (i.e. swapping the phase and the neutral)?
 
My HD-DAC1 has quite al lot of leakage current when I touch the case (I am VERY sensitive to this, my wife doesn't feel anything).  Leakage current + unfortunate grounding topology can cause hum, sometimes this is solved by swapping the phase and neutral on the power cord.  Unfortunately being in the UK, I don't have the option to swap the phase and neutral unless I swap the actual connection inside the HD-DAC1 (or make an illegal power cord).

 

[frankrondaniel]

  I notice you are in the U.S.  If you are using a 2-pin plug on the power cord, have you tried flipping it around (i.e. swapping the phase and the neutral)?
 
My HD-DAC1 has quite al lot of leakage current when I touch the case (I am VERY sensitive to this, my wife doesn't feel anything).  Leakage current + unfortunate grounding topology can cause hum, sometimes this is solved by swapping the phase and neutral on the power cord.  Unfortunately being in the UK, I don't have the option to swap the phase and neutral unless I swap the actual connection inside the HD-DAC1 (or make an illegal power cord).

 
Hi.  Unfortunately the shape of the power cord connection won't allow me to flip it around.
 
The folks at the vendor where I purchased the HD-DAC1 left me an email offering to trouble shoot the issue - hopefully they'll have some good ideas.  I get the feeling that I'll need to get yet another unit though.

 

[2leftears]

Hi.  Unfortunately the shape of the power cord connection won't allow me to flip it around.

The folks at the vendor where I purchased the HD-DAC1 left me an email offering to trouble shoot the issue - hopefully they'll have some good ideas.  I get the feeling that I'll need to get yet another unit though.

For what it is worth; mine also has a faint hum. But I don't hear this on either my HD540 or HD800 unless I set the amp on HIGH gain, and the volume control past 3 o'clock. I can tell you that I will not come anywhere near those settings for normal listening.

You may not want to hear this, but do bear in mind that these are all early production batches. Teething problems do happen, may only become apparent in mass production, and not present itself in the prototype development.

I hope they sort it for you...

 

[frankrondaniel]

For what it is worth; mine also has a faint hum. But I don't hear this on either my HD540 or HD800 unless I set the amp on HIGH gain, and the volume control past 3 o'clock. I can tell you that I will not come anywhere near those settings for normal listening.

You may not want to hear this, but do bear in mind that these are all early production batches. Teething problems do happen, may only become apparent in mass production, and not present itself in the prototype development.

I hope they sort it for you...

 
I don't get past 3 o'clock my self - even on Mid-gain!  The hum definitely increases with gain - HIGH certainly has more than MID but I still hear it on MID.  Unfortunately now that I've heard the hum it's difficult to ignore.
 
I realize that we're early adopters of HD-DAC1 but I've run into two possibly defective units so far, with the first unit losing the ability to lock on a sampling rate and now the hum.  It's a little disappointing, though I'll keep at it as I do like the sound paired with the HD800's.

 

[idabao]

I purchased HDDAC-1 from the 1st patch of shipment in early December 2014. Unfortunately, it was broken 10 days later and it can't be turned on anymore. I have to wait for replacement unit of two weeks time. During the waiting time, the agent repaired the broken unit for me. However I found after the repair, the sound is little bit harsh and not quiet and dark as the unit has not been broken. According to the technician, he just replaced the logic broad by simply pluging new one thereon. Thus I suspect that given interior space is so small and all cable and broad have to be inserted into such small area. It would be easily interfered on signal path if placing of those stuff is not in order or handle with enough care.  Now I get the replacement unit now and the sound from the new unit is so clean and smooth even using AKG 712 which is most sensitive phone I have. With HD-650, it is more perfect match with this amp than akg 712. The sound of this amp with hd650 is so musical and warm.  After burning in for  3 whole days, the treble is extended very well and the vocal is so touching. Also I found stock usb-cable is not bad and gold plate plug. When I use AQ carbon, however, its dynamic and soundstage are significant wider than stock usb cable.
 
Despite poor experience of my 1st unit, I still highly recommend those who look for headphone amp with dac of dsd capacity at this price range. 
 
 
I also have a question for unit owners. How many days for burning in of this unit to get sound stabilised?

 

[Tom-Dai]

First Time Post...
i burned in using a pink noise loop at night for about eight hours and listened to my normal playlist during the day. The Sound, especially the mids, started to open after 3 days.
At the beginning i was a bit disapointed about the mids. Snare drums and brass sounded not very natural.
But its gone now. After a week of normal play now, the sound does not seem to increase any further.
I am very satisfied with the sound as it is right now.
Had the Astell & Kern AK100 MK2 before with a Wolfson DAC-Chip. The Marantz Sound is very different, much more musically vs. the analytical and "english" sounding AK100.

 

[Hififox]

Did anyone compare hd-dac1 with woo audio wa7? Massdrop got a nice drop for wa7, so I'm considering between these two. My cans are senn hd600 and akg k701.