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iBasso D42 "Mamba" with dual dacs! !! Hey Hey! Improved Starting on Page 76 . - Page 28

post #406 of 1153

Huge thanks and a quick bit of clarity required

I've been reading this thread over the past few days and have a D4 winging across the waves as we speak :-) Thanks to you all for so much great info - much appreciated

I am still slightly confused with the variation between amp, amp/dac and dac usage. (Please bear with me!).

>> Amp only - LOD in from from my iPod with battery
>> Amp and dac - usb in from my MacPro
>> Dac only - usb in and lineout to amp downstream

Now what has my grey matter smoking is Headphone addicts words:

"And, it can be used as a line out DAC with just the USB and no battery installed, as well as an amp via USB with no battery".

It's the last bit, "amp via USB with no battery". How do you accomplish this?

Any help of clarity will be warmly received!
Best wishes,

Jon
post #407 of 1153
What Larry is saying is, if you take the battery out and connect the USB-make sure the switch at the back selects amp, you can use it as a amp.
post #408 of 1153
From the pictures, there is only one switch though... battery or usb... is the one you're speaking of an internal switch?
post #409 of 1153
Just the back switch, if amp is selected and no battery is installed then it would use the USB to power the amp,if the USB is connected.
post #410 of 1153
Sorry, I'm still very confused. I just want to understand how I can select amp only or dac only when using an USB input for source.

If I understand correctly, if I plug in my headphones with the USB source/power I am utilising both the amp and dac. If I use the line out, how do I select whether I am using the amp or dac?

Again, apologies for my "slowness" with this.

Jon
post #411 of 1153

Still confused...

Doh, double post.
post #412 of 1153
If you want to use the lineout, the switch at the back should be selecting the USB DAC and the USB should be connected to your source.Did I get your question correctly.
post #413 of 1153
Quote:
Originally Posted by mossman View Post
Sorry, I'm still very confused. I just want to understand how I can select amp only or dac only when using an USB input for source.

If I understand correctly, if I plug in my headphones with the USB source/power I am utilising both the amp and dac. If I use the line out, how do I select whether I am using the amp or dac?

Again, apologies for my "slowness" with this.

Jon
If you plug D4 into USB the DAC will be turned on, regardless of whether you have a battery in it or not, and regardless of whether the volume knob is switched on or not. The DAC will output through the aux in/out jack.

If you plug a cable into the front aux in/out jack the headphone amp is disabled, and you get a line out only.

If you plug a headphone into the headphone jack, the amp is activated and the amp can run on the 5v USB with no battery, or you can put in a 9v battery and flip the switch to run the amp on 9v.

With the amp set for 9v, the DAC will still only be using the 5v USB power.

So, with the amp set for 5v, both the DAC and Amp are running at 5v and it will not drain your 9v battery until you flip the switch to battery. So, you do not need to take out the battery to preserve it's charge for later like you do with the 3MOVE.
post #414 of 1153

Amp only is when.....

Aha, the clouds of confusion are rising!

So, the only way the D4 functions as an amp only, is when it is used with a DAP? (i.e. iPod > LOD > AUXIn).

Do I take it that the dac will always be functioning when using the USB source? (Or can you turn it off and just use the amp and send the signal to separate dac?).

Thanks for your patience
post #415 of 1153
Quote:
Originally Posted by mossman View Post
Aha, the clouds of confusion are rising!

So, the only way the D4 functions as an amp only, is when it is used with a DAP? (i.e. iPod > LOD > AUXIn).

Yes, that is correct. Amp ONLY = battery selected, aux input used by external source, USB not used.

Do I take it that the dac will always be functioning when using the USB source? (Or can you turn it off and just use the amp and send the signal to separate dac?).

Yes, whenever the USB is plugged in to a live computer, the DAC is active. You cannot turn off the D4 DAC when input is live USB. The decoded USB will always be available at the Aux output.

I cannot imagine why you would want to turn off the DAC and route to another DAC. Why not just remove the D4 and substitute another DAC?? or unplug the USB, use the D4 amp with its Aux input and hook up another external DAC.

Thanks for your patience
See answers above...
Ron
post #416 of 1153

Thanks very much

Quote:
I cannot imagine why you would want to turn off the DAC and route to another DAC. Why not just remove the D4 and substitute another DAC?? or unplug the USB, use the D4 amp with its Aux input and hook up another external DAC.
Agreed! I was just trying get it clear in my mind what the different scenarios were, especially around use with the USB input.

Thanks so much for everyone's help - much appreciated

Jon
post #417 of 1153
Just completed D4 Battery replacement project
Attached is a teaser picture. 2nd run already. Will there be a third edition ?



Changing battery would be a thing of the past.
Switching noise is slightly less than 3mV at 250Khz measured from my O-Silly-Scope, at the 12V output and input is not affected.

Owner is busy audition different op-amp combination currently, I think he will go crazy choosing.

So far this are the findings.
AD797*2 sounds really good on this neutral and all rounder.
OPA1611*2 if you prefer something more forward
and OPA827*2 more mellow

LT1028 sound like a very expensive hi fi setup but somehow it is not our taste. Sorry I do not know how to describe this better.

Found and did a few new tweak for the Power section of the D4 as well. I never heard Olivia Ong sound so sweet and loving.

I made a mistake in the previous post, The relay is ON when when the D4 is configure to use the DAC and AMP at the same time.

After listening to D4 Mamba, the following are some of the difference between the D4 and D10. Compared with same set of OP-AMP for both D4 and D10

D10 is more forward sounding, faster with more attack, timber is unique
D4 is very smooth, warmer and sweeter, more neutral.

Using IEM at low volume there is not much difference between 5v and 9V.
But using a higher voltage it made a huge difference, even for "easy" to drive headphone like HD595. I did not realize there where so much strain at higher volume. I might just consider getting a D4 myself to upgrade.
post #418 of 1153
Quote:
Originally Posted by madwolf View Post
Instead of changing battery ever 8 or 9 hours.
This is what I am working on.



A power circuit to be be powered from the 5V of the USB.
1) The circuit include a voltage doubler to convert the 5V supply to 9V or Higher.

2) Power regulator to fixed the output voltage

3) Filtering circuit and smoothing circuit, Currently I am experimenting with different configuration of Pie Filter. Will build the official module after I finalize the design and component used.

The module must be smaller than a 9V battery, So that it could fit inside the D4. It noise must not be audible using even the most sensitive IEM. (I am happy that my alpha attempt have already achieve this. ) The existing USB/9V switch will not be modified so that, the user could choose between the 2 power source.

The item yet to be decided is if I want to Push the D4 to 12Volts or 10.8V
To do this I might need to change the existing reservoir cap on the D4 (10V 2200uF, ibasso is already pushing on the limit by putting a 10V cap for a 9V battery) . But the advantage of this is that I could have the voltage margin to play with the holy 3 of OP-AMP, namely OPA627, LT1028 and AD797 for the LR. Buffer would likely be the BUF634 *4 in wide-band mode. A higher voltage would have a greater headroom as well, But there is a limit to how much power I could draw from the USB.

I will continue to tinker with the design and hopefully improve it further.

The Sick part of all this, The D4 and power circuit is not mine, Just modding for fun for a friend FOC. I feel I starting to enjoy modding circuit more than listening to music already.
Quote:
Originally Posted by madwolf View Post
Just completed D4 Battery replacement project
Attached is a teaser picture. 2nd run already. Will there be a third edition ?



Changing battery would be a thing of the past.
Switching noise is slightly less than 3mV at 250Khz measured from my O-Silly-Scope, at the 12V output and input is not affected.

Owner is busy audition different op-amp combination currently, I think he will go crazy choosing.

So far this are the findings.
AD797*2 sounds really good on this neutral and all rounder.
OPA1611*2 if you prefer something more forward
and OPA827*2 more mellow

LT1028 sound like a very expensive hi fi setup but somehow it is not our taste. Sorry I do not know how to describe this better.

Found and did a few new tweak for the Power section of the D4 as well. I never heard Olivia Ong sound so sweet and loving.

I made a mistake in the previous post, The relay is ON when when the D4 is configure to use the DAC and AMP at the same time.

After listening to D4 Mamba, the following are some of the difference between the D4 and D10. Compared with same set of OP-AMP for both D4 and D10

D10 is more forward sounding, faster with more attack, timber is unique
D4 is very smooth, warmer and sweeter, more neutral.

Using IEM at low volume there is not much difference between 5v and 9V.
But using a higher voltage it made a huge difference, even for "easy" to drive headphone like HD595. I did not realize there where so much strain at higher volume. I might just consider getting a D4 myself to upgrade.
Let us know how that sounds with HD600/650 or 600 ohm AKG or Beyer someday.
post #419 of 1153
Quote:
Originally Posted by HeadphoneAddict View Post
Let us know how that sounds with HD600/650 or 600 ohm AKG or Beyer someday.
How would the change in battery to a chargeable one affect sound in any way, what is the voltage swing that we can get.
post #420 of 1153
Quote:
Originally Posted by kunalraiker View Post
How would the change in battery to a chargeable one affect sound in any way, what is the voltage swing that we can get.
You can get more voltage swing from a 9v alkaline than a std 8.4v re-chargeable, but in my opinion an alkaline should only be used when your re-chargeable is used up because the alkaline cost so much. The 8.4v re-chargeable is close enough in voltage that I wouldn't waste the money on alkaline.

However, there is a 9.6v re-chargeable out there which I used in my Headroom Micro AMP and DAC, which don't last very long but have better voltage swing for high impedance phones.

In my case, I would rather use a 500 mah lithium rechargeable 8.4v cell than the alkaline or 9.6v that have to be changed out more often. But, in my case I also mostly use the D4 as a desktop amp with laptop, and I use a smaller RSA P-51 or iBasso T3 with longer battery life for portable .
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