 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
75.142.52.0
A number of years ago I purchased a Gustard x20pro DAC and had Igor Kuznetsoff of the N.J. Audio Society modify it with bypass caps, damping, etc.
I noticed at first that the sound was much improved compared to my iFi Nano, but I was getting something undesirable, which was a resonance in my headphones on certain notes. I have a musical keyboard and piano synthesis software on my MacBook, so I played different piano notes along with a spectrum analyzer plugin and a parametric EQ, and determined that the resonance was happening at around 500 Hz. (C above middle C). There was another resonance an octave above that.
This resonance is also particularly noticeable on choral music.
It wasn't too bad at first, but since then a pattern has become obvious. Every time I improve the Gustard, the resonance gets stronger and more noticeable.
For example, putting a good power cord on the Gustard (a custom job by Igor) improves the transient attack speed and extension, but also worsens the resonance. And now using a better USB source, the Zen Stream, worsens it further, at the same time it makes the sound more immediate and exciting.
So what I'm trying to figure out is whether this is due to a problem in the Gustard (for instance, is this its sonic signature), or whether the problem is a resonance in my ear canals or the cavity inside the headphones.
If it's a resonance in my ear canals when using headphones, would it tend to worsen as the transient speed improves? Does this have nothing to do with DAC, but entirely to do with the kinds of improvements in the sound that going to a better DAC or source USB signal provides?
I also notice some shrillness in my system as the source USB signal improves, and I notice that over speakers too. That might also be in the DAC.
I'm going to do some experiments now with switching out the DAC.. I still have the iFi Nano and also a 24/96 DAC that was modified by Igor (forget the brand).
Follow Ups:
Turns out that vibration isolation of the DAC solved the problem of shrillness on strings. I think the resonance is still there but I have to test it with a lot of different material.
For vibration isolation, I used squash balls sitting inside cups with a dollop of damping material. I got these from Igor Kuznetsoff. I asked him about spikes, and he said that spikes can change the resonance frequency of the device's chassis, but they don't actually reduce vibrational energy. Squash balls are a kind of spring-and-weight system, like shock absorbers on a car, and if you put about 4 pounds per ball they act like a low pass filter, letting through very low frequencies but reducing anything above that.
I'm surprised at how effective they were on the DAC.
If you find your headed in the right direction with vibration isolation using footers, I wonder if Igor did the internal toroidal transformer decoupling mod popular for your dac. The transformers may be the main cause of the vibrations in the first place.
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
I haven't heard of this mod. By "decoupling" you mechanical isolation, correct? I know Igor put some damping material in the chassis and on the master clock crystal.
Do you have a link to a webpage describing Gustard mods?
thanks
Sure thing. Here are 2 links.http://tweakaudio.com/EVS-2/Gustard_X20_Mods.html
http://tweakaudio.com/EVS-2/X20U_Pro_information.html
I've been looking at doing something like this to the toroidal transformer in my CD Transport.
In the X20 and X20pro links they replace the metal with nylon bolts and incorporate cardboard. Or they just use glue, cardboard and no bolts at all.
Jonesy
Edit: Sometimes the existing transformer bolts come loose and just need to be tightened. Conversely they can be too tight. Since your Dac has been in transport a bit, checking the bolts and rubber washers might be all that is needed .
"I know just enough to get into trouble. But not enough to get out of it."
Edits: 04/11/24
What does reducing vibration in a DAC chassis have to do with solving the problem of shrillness on strings - IN YOUR HEADPHONES ??
"For vibration isolation, I used squash balls sitting inside cups with a dollop of damping material."
Will you be stuffing squash balls inside your HEADPHONES to solve your 'resonance problem' too ?
I'm lost but whatever works for you!
Why not try another outboard DAC ?
Why not try not using an outboard DAC at all ?
Why not try a different set of headphones ?
Why not try not using headphones at all (using a pair of speakers instead) ?
Why would a DAC (any DAC) produce a 'resonance' at specific frequencies ?
Yes, I tried all those things, but not until after posting my original message. I probably should have tried all that before posting, but in any case I'll fill you in now.
Basic conclusion: I tried other DACs, and got one working that had close to the transient power of the Gustard, yet did NOT have the resonance.
In addition, I tried other headphones and my speakers. With the Gustard, the other headphones had a clear resonance. It's not as clear through the speakers, but it seemed to be there.
I tried driving the DAC via USB from two different USB sources (the Zen Stream in different configurations and my old NUC). With the lower quality USB source, the Gustard has less transient/attack power, and the resonance was less obvious. With a higher quality USB source it was more obvious.
Why would a DAC produce a resonance? Well, maybe it was broken. Igor modified a lot of stuff about it and maybe introduced the resonance. He's pretty good at what he does and listened to the results of his work throughout the process, so it's hard to believe he would have broken it that badly.
Just kidding.
Gerry
Lack of skill dictates economy of style. - Joey Ramone
What's wrong with Gustard? their DACs are terrific, altho I'm not familiar with the older X20.
Having said that, my X26Pro was disappointing at first: it sounded worse than my previous A18! It took a lot of care (footers, power cable, coax cable) to finally sound (much) better than its little brother.
Not as good as my current DAC, but still a very good product. Never heard a Schiit, though.
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
