The peak current rating of the UF4007 is sufficient that this seems less concerning than it once did. I wouldn't be concerned about using them in this application.
Noise with Computers, USB DACs, and Powerline Ethernet Kits
- Thread starter Paul Birkeland
- Start date
They could be a little bit on the large side physically, but electrically they will work OK.
elgringo81
New member
Can this mod be installed on an Eros v1 and Mainline as well?
D
Deke609
Guest
elgringo81 said:
Paul Birkeland said:
elgringo81
New member
Thanks, I seems to have missed that info.
Are you feeding your Eros with a signal from a computer? If not, then I would not install this in a phono preamp.
Yes, they would have skinnier leads.
SeaCaptain
New member
I'd love to try this mod, but the only diodes I've got on hand are 1N4001, which are rated to 1A.
It's been quite a while since I built my crack, but can you confirm for this beginner that I should find a different set of diodes to use?
It's been quite a while since I built my crack, but can you confirm for this beginner that I should find a different set of diodes to use?
The peak current capability of the 1N4001 is 30A, which is more than enough to get the job done.
baseonmars
New member
Hi - would 1N5408 work here? Rated at 3A and 1000V? the datasheet says it's a rectifier diode. I'm not sure if that's a problem in this application?
The peak/surge current is 125A, so no problems there.
Forgive my ignorance, but am I understanding this correctly?Paul Birkeland said:
It sounds like this will prevent voltage under 0.7V from passing through the diode bridge.
I presume the noise coming from a nearby PC/USB DAC is somehow linked to small changes in voltage sent through the power cable, and somehow this small resistance will prevent these changes from translating into the audio signal.
It's not exactly a resistance, it's more of an open circuit below a certain threshold.
Crackling
New member
I had severe noise problems with two different Crack amplifiers that I had acquired no matter what DAC I used as long as the main source was my computer's USB port. Tried ALL my USB ports including a powered and unpowered USB hub too. Regardless, the noise was very much available and loud especially when I started playing a video game on my PC or did anything that put my GPU to work. Used at least 6 or 7 different models and brands of DAC. Then I found out the same happened with other tube amplifiers too (DV and woo) so it was definitely my system. Tried a myriad of USB noise reduction gizmo from iFi. Tried all sorts of fancy power cords both for my Crack and my PC to no avail. Some of these would reduce the noise a little bit or change its nature somewhat but it was still there and in full force! Ultimately did the resistor mod suggested here and just like magic, all the noise disappeared... But I couldn't find a similarly simple solution for other tube amps, so continued my troubleshooting steps until I came across this magical USB isolator after having read about it on various forums:
https://hifimediy.com/product/hifime-high-speed-usb-isolator/. The noise is now completely eliminated with all my tune amps. I have tried it with an Topping E30 and SMSL SU-8 v2, Khadas Tone Board, and a few other DACs I can't even remember in combination with my two non-Crack tube amps and no noise whatsoever... Now I've been tempted to remove the resistors from my Crack to test it with this to see if the noise will be gone, but don't feel adventurous enough.......yet.
Sorry for the super long post, but it was driving me crazy trying to eliminate the weird noise problem I was having, so I figured I'd share some of what I went through and what ultimately worked for me in case it can also help someone else out.
https://hifimediy.com/product/hifime-high-speed-usb-isolator/. The noise is now completely eliminated with all my tune amps. I have tried it with an Topping E30 and SMSL SU-8 v2, Khadas Tone Board, and a few other DACs I can't even remember in combination with my two non-Crack tube amps and no noise whatsoever... Now I've been tempted to remove the resistors from my Crack to test it with this to see if the noise will be gone, but don't feel adventurous enough.......yet.
Sorry for the super long post, but it was driving me crazy trying to eliminate the weird noise problem I was having, so I figured I'd share some of what I went through and what ultimately worked for me in case it can also help someone else out.
D
Deke609
Guest
For the purpose of this mod, you can think of a diode as erecting a barrier that is approx. 700 mV tall: @700 mV and below, no current flows, but everything above 700 mV passes over the barrier. (The "height" of the barrier, called the diode's "forward voltage" -- the minimum voltage required to turn the diode "on" and permit voltage and current to pass, varies a bit by type of diode). This applies to a "forward biased" diode - i.e., one where the anode is more positively charged than the cathode (banded end). Because the mod uses two "reverse paralleled" diodes, there is a forward-biased diode in each direction: to earth ground and from earth ground -- so it blocks sub-700 mV currents in both directions.
In reality, the "barrier" is sloped and some small amount of current makes it through when the applied voltage is less than 700 mV. See attached graph, and specifically the region to the right of the X,Y origin.
cheers, Derek
In reality, the "barrier" is sloped and some small amount of current makes it through when the applied voltage is less than 700 mV. See attached graph, and specifically the region to the right of the X,Y origin.
cheers, Derek
Attachments
Crackling
New member
One thing I have noticed after doing the diode mod is that my tubes, especially the power tube, doesn't get as brightly lit as before or as compared to when I use the same power tube in another tube amp. As you can tell from my posts, I severely lack technical knowledge in this area, but is this a general side effect of this mod?
