Geshelli Labs NEW J2 Dac

[ousi]

For the Adam T5v, the user manual has a better picture. The website is missing the value.
https://www.adam-audio.com/content/uploads/2020/10/adam-audio-t-series-user-manual-english.pdf (Page 11)

Balanced input has sensitivity of +4dBu, single-ended one is -10dBV. Both seems to be "standard". The single-ended one is differed in level than the balanced input by around 12dB. Hence, jmaz87 has to crank up the gain on his T5v to achieve the same volume level as the single-ended input, which for the J2 and JNOG, both output has the same voltage.

 

[Lambda]

Balanced input has sensitivity of +4dBu, single-ended one is -10dBV. Both seems to be "standard". The single-ended one is differed in level than the balanced input by around 12dB.

Yes both are Standard and as said before this standard +4dBu for XLR is 1.227V RMS.

but the lower output of J2 needs me to add more gain at each monitor resulting in hiss... so its audibly worse... and RCA has ground loop...

You can't change the gain of this monitors amplifier you can only change input attenuation.

Voltage Dividers - learn.sparkfun.com

A90 is designed around a 4VRMS input from a balanced dac right? what am i missing.

The A90 can actually change the gain.

The JC2 definitely has a different sensitivity for XLR. I don’t know which they list in that section. I had tried connecting a CD player with RCA and then switched to XLR with a converter (RCA to XLR, as I have a Cardas converter laying around) and the volume level is different.

Sure it is -10dbu for rca and +4dbu for xlr

For LS28 the max input it can take is 16Vrms for balanced and 8Vrms for SE. It’s right above what you quoted above. https://audioresearch.com/product/ls28se/

Only if volume is turned all the way down

Voltage Dividers - learn.sparkfun.com

The gain is fixed at 18.5dB

 

[jmaz87]

so the "level" knob on back of each (and the one on sub...) that goes from -60dB to +18dB isn't referring to gain or were just using the wrong word and instead of a dialogue ur just like nah wrong...when it goes above 0dB??? how does is add signal??? voltage?

well J2 doesn't put out enough to get good volume with T5v. Plenty of people run a DAC to powered monitors. what am I missing.

Even with the much higher output of Bifrost 2 I need to use med-gain on A90 past 12 oclock for "loud" listening depending on content. some twitch streams are too loud at 11oclock low gain but most flac files i play need medium gain.

if the class D-amp is always applying the same gain then why is there audible hiss when set higher regardless of signal or input? there's no signal to attenuate with nothing plugged in...

keeping my "not gain knob" below 0dB (I currently have both set at 12pm) this lets me use the A90 in low and mid Gain depending on content (rarely need mid-gain for headphones) which is nice because i have a lot of volume control this way.

is there a better way?

 

[Lambda]

so the "level" knob on back of each (and the one on sub...) that goes from -60dB to +18dB isn't referring to gain when it goes above 0dB??? how does is add signal???

In this case it is actually labeled right.

The Amplifier apples always 18dB gain. but before the amplifier there is Attenuation. a potentiometer acting as an (voltage) divider.
So you get -78dB to 0 dB from the level knob and +18dB from the amp resulting in -60 to +18dB

if the class D-amp is always applying the same gain then why is there audible hiss when set higher regardless of signal or input? there's no signal to attenuate with nothing plugged in...

How did you test this? open input?
For this test you need to have shorted or defined terminated input.

keeping my "not gain knob" below 0dB (I currently have both set at 12pm) this lets me use the A90 in low and mid Gain depending on content (rarely need mid-gain for headphones) which is nice because i have a lot of volume control this way.

is there a better way?

Hard to say if there is a definitive better way. It also Depends on how much noise is pieced up from the environment because of bad cables, emi or ground loops.

But ignoring this factors
The general rule to get the lowest noises is
"Don't Attenuate after amplification."
Every Amplification or attenuation Adds noise the higher the gain the more. so you want to avoid unnecessary amplification.

so if the A90 goes loud enough with gain at Low and volume knob at max its is gonna perform better then gain at medium and volume perform at 12o clock

So Volume controls (with some rare exactions) are Negative Gain attenuates -infinite to 0db with a fix Positive gain.
The lower the absolute applied gains positive and negative the lower the noise.

 

[jmaz87]

How did you test this? open input?
For this test you need to have shorted or defined terminated input.

Regardless of RCA / XLR / Nothing connected the audible hiss behaves the same as you turn up the "level" which is typical with most powered monitors no?

It's not uncommon to run DAC direct to powered monitors I just checked Adams user manual and it literally says you don't need any external amplification.

Originally using E30/L30 via RCA it honestly sounded perfectly fine and I used similar volumes at low and medium gain as I do with A90 I simply turned the "Level" at monitor down so hiss was below my threshold of hearing from my desk.

the ground loop however was constant regardless of anything else, as long as Dac was connected via usb to PC...

J2 fixes ground loop but using XLR its too quiet...

 

[Lambda]

Regardless of RCA / XLR / Nothing connected the audible hiss behaves the same as you turn up the "level" which is typical with most powered monitors no?

Nothing connected is not a useful test.

It's not uncommon to run DAC direct to powered monitors I just checked Adams user manual and it literally says you don't need any external amplification.

Yes it is not and you shuld be Abel to get full power. The Speaker says reference level is +4dBu this is less then 2Vrms

 

[ousi]

Thanks for all the explanation. I missed out the part that there is an volume knob on preamps/power monitors. So the input sensitivity should indicate that +4dBu for XLR should give us a specific output, but likely at the 100% volume knob level? I've never used the LS28 at 100% (more like 20% to 30% most) because when I go over 40% the background noise could be heard (typical of tube gears, even though this one is already quite quiet).

I'm more curious about jmaz87's case, as to why the hiss become louder if the amp inside is at fixed gain level.

 

[Lambda]

n. I missed out the part that there is an volume knob on preamps/power monitors. So the input sensitivity should indicate that +4dBu for XLR should give us a specific output, but likely at the 100% volume knob level?

Usually sensitivity is rated at 100% with PreAmp 100% means 0dB attenuaton from the knob.
or if the knob has 0dB marking it is there
Lot of Active speaker have 0dB at 12o clock and go only +-15dB

So if you have a DAC that outputs 2Vrms (+6dBV or +8.2dBu) and you want to go in a monitor with a +4dBu input you need to dial in -4.2dB at the volume knob.
so a just a bit shy of 100% or the 0dB mark.
In this caes you have 8.2 -4.2dB = 4dBu

If you add an extra preamp with lets say +18dB and it is at 50% (lets assume 50% is -9dB) the Preamp output is 8.2+9 =17.2dBu.
the speaker would need to be set to -13.2dB at the volume knob to get full power.
So in this cases you go +8.2 -9 +18 -13.2 = 4dBu
so lots of unnecessary gain steps.

 

[jmaz87]

definitely appreciate the explanation!
still doesn't explain why I need to go above 0dB at monitor with J2 when it should be more than "full power" @2Vrms for usable volume in a small office.

and if the hiss increasing with level is the same with either inputs OR nothing it eliminates the inputs as the source of hiss... making it relevant. its not a test just a testable observation

having the monitors set a bit below 0dB makes his completely inaudible but your saying i'm massively overdriving them this way? both channels go through the sub too if that is relevant idk

 

[Lambda]

If they are not to loud your not over driving them.

having the monitors set a bit below 0dB makes his completely inaudible but your saying i'm massively overdriving them this way?

Are you driving them with 4Vrms? because this would only be 3dB more.
Even if you get 3dB more hiss by increasing the volume at the speaker 3dB it is unlikely this 3dB makes the difference this big:

makes his completely inaudible

So im not sure what is exactly going on with your setup.

 

[jmaz87]

most monitors have hiss above a certain volume. idk i thought it was superduper common.

signal chain is PC usb Bifros2 xlr A90 xlr T10s xlr T5v

don't know how else you would to this ^

J2 sounded fine but i had to turn the level on monitors up and hiss was audible. this was the same for any scenario regardless of input.

having a higher output signal even via RCA (E30/L30 stack) sounded great too and i had the monitors set the same as they are now so no hiss.. but i had the ground loop.

 

[jmaz87]

just happened to see this finally got a review see what amir thinks about the output levels of this DAC lol I still enjoy it as a stack but ya its weird

JNOG Review

 

[ousi]

most monitors have hiss above a certain volume. idk i thought it was superduper common.

signal chain is PC usb Bifros2 xlr A90 xlr T10s xlr T5v

don't know how else you would to this ^

J2 sounded fine but i had to turn the level on monitors up and hiss was audible. this was the same for any scenario regardless of input.

having a higher output signal even via RCA (E30/L30 stack) sounded great too and i had the monitors set the same as they are now so no hiss.. but i had the ground loop.

Hmmm, in that case does it warrant to have a Topping A90 between the J2 DAC and the monitors so that you don't need as much gain to eliminate the hiss? The A90 also measures remarkably well, matching the HPA4. I have both and my ears cannot tell the difference, except when at low volume level the A90 has channel imbalance. But you can put the preamp/headphone amp into low gain mode and crank up the volume knob to go past the channel imbalance range. The A90 has nice toggle switch in front to go between headphone and preamp mode, so no more headphone plug/unplug to use the pre-out.

The other choice would be to get the E2 from Geshelli.

 

[jmaz87]

I got the Bifrost 2 as an alternative to the D90SE since both have similar outputs and A90 was designed around that.

while I'm sure I could use the A90 with J2, I would need even MORE gain from A90. Again the hiss is not coming from anything but the class D amp in the monitor its a well known issue that some monitors have worse than others...

the reality is I don't need even the A90's power with the Headphones I own... even hd6xx rarely needs med gain and more often stays below 50% low gain

having the Geshelli Stack in LivingRoom is nice but even there I miss using the E30 remote to change inputs and attenuate volume for late night casual listening.

 

[Lambda]

would need even MORE gain from A90.

And whats the problem with this?

Again the hiss is not coming from anything but the class D amp in the monitor its a well known issue that some monitors have worse than others...

So if the inputs are shorted! (not open) the monitors have more hiss at higher/full volume?

 

[Bob_C]

I would like to use a pi4 connected via usb to the J2 (with usb option) and send that signal on to an akitika pre-amp.
I can’t seem to find a better option in the J2’s price range.
Questions:

1. can anyone see a problem with the proposed setup?
2. Has anything come out recently that would compete with the J2?
3. Which Dac chip should I select for the J2?

Regards,
Bob.

 

[alpha_logic]

I would like to use a pi4 connected via usb to the J2 (with usb option) and send that signal on to an akitika pre-amp.
I can’t seem to find a better option in the J2’s price range.
Questions:

1. can anyone see a problem with the proposed setup?
2. Has anything come out recently that would compete with the J2?
3. Which Dac chip should I select for the J2?

Regards,
Bob.

1) No, should work fine.
2) Not recently released, but the Schiit Modius compares in this price category; I have both, the J2 and the Modius, and no - I don't think I could tell a difference in a blind test between the two DAC's.
3) I selected the 9026pro - I haven't seen any measurements specific to the J2 that would elevate one chip over the other, but the 9026pro seems to be the 'reference' chip.

 

[Bob_C]

I am having a rough go of getting sound out of my J2. I am only using the USB output in these scenarios.
Throughout the process, I confirmed I was on the correct input (right column of LEDs flash once) and I also cycled through the three volume settings.
I started out using volumio running on a pi4 --->USB--->J2--> RCA -> Marantz
Then I installed RoPieeeXL on the same pi4 --->USB--->J2--> RCA -> Marantz
Then I tried using my laptop, so it was windows10 (using JRiver software and VLC) --->USB--->J2--> RCA -> Marantz
After the first attempt with W10 I upgraded the USB driver
Observations:
When I plug the J2 into USB on the laptop, it is seen as a speaker.
When I played an SACD track I even saw the DSD light come on.

I tried all the normal things, I know the rca patch cables are good, I know there are no issues with my amplifier.

Thought or suggestions?

Bob.

 

[alpha_logic]

I am having a rough go of getting sound out of my J2. I am only using the USB output in these scenarios.
Throughout the process, I confirmed I was on the correct input (right column of LEDs flash once) and I also cycled through the three volume settings.
I started out using volumio running on a pi4 --->USB--->J2--> RCA -> Marantz
Then I installed RoPieeeXL on the same pi4 --->USB--->J2--> RCA -> Marantz
Then I tried using my laptop, so it was windows10 (using JRiver software and VLC) --->USB--->J2--> RCA -> Marantz
After the first attempt with W10 I upgraded the USB driver
Observations:
When I plug the J2 into USB on the laptop, it is seen as a speaker.
When I played an SACD track I even saw the DSD light come on.

I tried all the normal things, I know the rca patch cables are good, I know there are no issues with my amplifier.

Thought or suggestions?

Bob.

Have you installed the windows amanero drivers? https://amanero.com/drivers.htm
Also, you are actually getting output on the pi4, correct? For USB input, the 'Input Status Leds' column on the right should flash twice, not once: https://geshelli.com/wp-content/uploads/2022/06/jnog2-user-manual.pdf

 

[Bob_C]

Have you installed the windows amanero drivers? https://amanero.com/drivers.htm
Also, you are actually getting output on the pi4, correct? For USB input, the 'Input Status Leds' column on the right should flash twice, not once: https://geshelli.com/wp-content/uploads/2022/06/jnog2-user-manual.pdf

Thanks for the suggestions alpha_logic
Turned out to be user error. The CD input on the marantz was set to digital, I made the assumption that it would auto detect the input that was actually being sent a signal, there was no other CD connection.