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Groch
70
Sep 5, 2019
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I am tempted BUT, I got rid of my XD-05 because all of the gain settings (+6, +9, +15) were too high...so that I could not adjust the volume well with high efficiency IEMs. Just the slightest turn above 0 and they blasted. This has double the output so it could be worse. I have seen no spec for gain on this new Plus model. I guess I have to wait for user reviews.
Sep 5, 2019
MiniMax
65
Sep 5, 2019
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I use the XD-05 with several IEMs. none of them is too loud: DMG, T01, several KZ, Mee. What are those (very) high efficiency IEMs of yours?
Sep 5, 2019
Groch
70
Sep 5, 2019
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I referenced this on my comment on the original. I am not sure whether the issue is the gain switch or the volume pot taper. It is not that I could not get it to play softly, it is that on many of my headphones I could only use the bottom 1/4 of the volume control....which makes fine adjustments difficult. My concern is that since this new version has double the power, will the issue get worse.
(Edited)
Sep 5, 2019
Qwervy
411
Nov 12, 2019
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I got my xd-05 plus recently and I agree with you, its borderline impossible to play softly without turning down the source volume (which reduces bit depth and therefore dynamics and sound quality). I think that this could be fairly easily fixed by adapting the low gain setting to a plus 3db rather than 6 which would be more useful IMO. However, the gain circuit might not be as simple as a negative feedback loop (which I am hoping it is). I have yet to try my Tin T2 Pro's on it but I will be looking at the gain structure when I open up the amp to do the V5i mod. The alternative is you can make an adapter from 1/4 inch to 1/8 inch with a built in resistor or to drop your volume.
Nov 12, 2019
SteveSterns
0
Feb 4, 2021
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Did you ever end up seeing if you could adapt the low gain setting to be plus 3 db?
(Edited)
Feb 4, 2021
Qwervy
411
Feb 4, 2021
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Unfortunately not, I would need to do a degree in electrical stuff to fully get the circuit. It's a multi-layer pcb and it's just a pain to reverse engineer with my skillset. I gave it a shot over a few months after that post but then gave up because it was so complicated. I will definitely revisit it, thanks for reminding me. On the other hand, I did learn how to make an L-pad which changes volume without negatively affecting sound quality.
Feb 4, 2021
SteveSterns
0
Feb 4, 2021
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Oh nice, do you mind sharing more about the L-pad?
Feb 4, 2021
Qwervy
411
Feb 5, 2021
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Okay, so an L- pad consists of 4 resistors, 2 in series and 2 in parallel (1 per channel). If you were to look at each channel separately this is what the schematic would look like.
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Now keep in mind, this is just for 1 channel and you would need 2 of these (attached to a common ground) The value of R1 is going to change depending on how much you want to attenuate an the value of R2 is depending what the output impedance is going to be. R1+R2 is going to be the load that your amplifier sees. R2 being the resistor determining the output resistance of the circuit is an important part of making sure that the sound quality is unaffected. Basically, you want this resistor to be between 0.5 and 2 ohms max, unless you are only going to be driving high impedance cans. You want the impedance value of your lowest impedance load (headphone or IEM) to be 8 times higher than the value of this resistor. For example, if you have a 16 ohm IEM then you want at least a 2 ohm R2 resistor (or lower). Now for R1, this is where you are going to have to do some experimenting, I used Foobar2000's volume adjuster to see how much attenuation I would like, or how much would be safe. Then I used VituixCAD2 (electronics modelling software) to see how much attenuation I would roughly achieve (because I'm too lazy to calculate it myself). If you would like to use VituixCAD2 to calculate the amount of attenuation you are going to achieve then here is how you can do it.
  • First off in the 'drivers' section you are going to need to create a driver with a 'z' (impedance) to the impedance of one of your headphones (normally, 16 or 32 ohms).
  • Then go into the crossover section and make up the circuit (that I showed you in the picture above) with the squiggly line at the 'in' and the driver at the 'out'.
  • From here you should be able to change the value of R1 to whatever you want and scroll it up and down to see how attenuation changes in the 'filter' box on the right side of the screen.
  • I suggest playing around and increasing and decreasing the drivers impedance to see how it is going to affect the filter amount (as that does create slight variances in the attenuation) to make sure that you are totally happy with the values you have selected.
You can (just) squeeze this attenuation circuit into the housing of a stereo male 1/4 inch connector if the housing is big enough and then put a female 1/8 connector on the other side with some shortish (or longish) cable between the two if you like.
Feb 5, 2021
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