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Ever since I removed the potentiometers after my IVY, connecting the IVY (v2) directly to my amp (a balanced beta22), I experience a problem with noise (the TV snow type). Also, there is a slight dc offset (several mV) on the IVY output, that is amplified by the beta22 amp. Of course, with the potentiometers in place the noise part can again be solved (sort of) but that was not the idea of having a volumite  added to the bufallo. Then I noticed that the manual for the IVY has been revised regarding the recommended parts for connection to a Bufallo (version 1). For instance, c13-c18 are added, some resistors removed. Are these two modifications (i.e. IVY manual v1 vs v2) going to be helpful to remove the residual DC offset on the IVY outputs? What else (except putting the potentiometers back in) could be done to tame the DC offset to 0V?
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Hello,
I've got the IVY V2 and buffalo1 too and the same config as the IVY directly connected with my dual mono amps (newclassd NCD1).
Iv'e got the same problem with tv snow noise.
I've tried differents configs to find the origin of the problem. I've used symetrical and asymetrical connections without results.
When i touch the cables the noise change and sometimes it disapeared. I've tried shielded cable and not without results too.
One interessant thing: When i connect only one channel to his mono amplifier and let the other without connection cable the noise is acceptable. But if i connect the other channel cable to the output of the ivy even without connecting it to the amplifier the noise reappared.
With this last test i think it's not a loop ground problem but a high sensibility to HF (the other cable only connected to the ivy is sufficient to work as an antenna?).
I'm disappointed with this problem. I'm waiting to an IVY 3 but i'm not sure it would resolve the problem.
Have you some ideas?
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I have never seen this occur myself. You may have very capacitive cables. I would try putting a small value resistor (say 21R) in series with each of the outputs. Pictures of the application may help spot other possible issues. IVY-III has a much more robust scheme, and should not present such a problem. Edited by user Monday, May 17, 2010 5:49:43 AM(UTC)
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The NCD1 amplifiers have a relatively low impedance (5k) and a high gain.
When i'll receive the ivy3, i'll try with and without R27-30. That's it?
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I think you are on the right track.
Still if you like you could add the Rs to what you have now.
Also try running with neither C1-4 or C13-16.
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 I've received and assembled the IVY3 with the resistors. No audible noise at more 20cm of my 95 db loudspeakers. It's quiet! I yet use diy non shielded symetrical cables. Now, Buffalo II ?
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I hope you don't mind me reopening this thread. I am again (actually, still) searching for a better solution to remove the hiss mentioned in the first post. I currently use resistors to remove the hiss, though I noticed they add some unwanted coloration to the sound, so I would ask for your help finding a better solution. As for the resisitors: each of the 4 balanced outputs from the IVY 2.0 has a 6.4k ohm resistor in series and a 10k ohm resistor going to ground. It follows using volume pots on the output of the IVY before I started using a Volumite : they seem to remove the hiss. It may be equivalent to what is elsewhere referred to as a 'hiss-buster', although the resistor values may be totally wrong for that. It may be wrong altogether. - I searched the forum for similar issues + solutions and did not find them. - Since then I moved the Buffalo/Ivy PSU parts to a separate enclosure, but it did not seem to help. - I use the Ivy 2.0 board (yes, with the 21 Ohm resistors for R21 and R22 as suggested above). - The Ivy receives +/- 15.00 volt. - I double checked the balanced beta22 boards: seems be be set up okay and dead quiet with inputs shorted. I have attached a picture of my current setup, with a USB-input, OTTO, Buffalo 1.1 and IVY 2.0 stacked and resistors on the IVY output in place. DC for amp & dac comes through two separate ~1.5ft long 8-wire umbilical connectors (bottom of image). Wires inside the enclosure are quite long, though using shorter pieces inside the enclosure did not help. Do you think that replacing the IVY with an IVY III would be worth a shot, as t helped the second person in this thread?tuneable attached the following image(s):  DAC+AMP_small.JPG (219kb) downloaded 50 time(s).You cannot view/download attachments. Try to login or register.
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A few things to try before ditching the IVY. - Increase then distance between DAC and IVY - or change to a flat side-by-side layout. - Use shielded cable between DAC and IVY. Its a long time ago but from my first Buf. build I remember struggling with some noise. The cure was the above. I think I have a picture here somewhere ... from a prototype. Yes, any you can see I inserted a shielding between the DAC and IVY. Oh yes, and keep the datalines to the Volumite far away from the connections between DAC an IVY. Edited by user Saturday, August 18, 2012 7:25:43 PM(UTC)
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the IVY-3.1 has a significantly better filtering scheme. It could be that the stage after your IVY-2 maybe be sensitive to some of the hash that could be getting through.
As ACR300 said pay careful attention to wire routing and dressing.
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1 user thanked Russ White for this useful post.
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Thanks! Also for staying polite, even on the sight of such a cable spaghetti. I wanted to let you know I am working with your suggestions, but it will take some time to visit all of them. I have started by 1) turning the amp boards for better routing of the inputs and 2) taking the DAC/IVY unit far away. Without the resistors on the IVY output and with the "guts" out the noise level is reduced, but its not inaudible yet. I'll source some shielded wires now and see how things work there. edit: I'll also see if I can insert such a metal plane separator. thanks for sharing it. Edited by user Wednesday, August 22, 2012 7:45:21 PM(UTC)
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Also try separating DAC and IVY - flat side-by-side layout - or just increase the distance between the 2 in the stack. IMO the shielded cable is a must. Edited by user Thursday, August 23, 2012 2:46:42 PM(UTC)
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It has been a while since I brought this up, but I meanwhile tried a list of things, including
- trimed about every connection in and outside the enclosure.
- Shielded connections for the DC input (buffalo, IVY) between the PSU enclosure and the dac/amp enclosure.
- Shielded connections for the signal input (buffalo to IVY) and output (IVY to Beta22).
- Removed the OTTO/USB2SPDIF unit, for now, for direct input of the TOSLINk-SPDIF unit to the buffalo.
- Moved the AC-DC parts to a dedicated PSU enclosure.
- Moved the whole buffalo/Ivy/volumite setup as far away from the amp units as possible.
(- short-circuit on the PSU outputs while checking the rewiring, which then needed to be repaired... )
The situation I have momentarily:
- No noise (as in the first post of this thread)!
- But, one side is not okay. The right channel sounds lower volume and distorted. I can switch the L-R inputs on the IVY2.0 without improvement or change (so its not the buffalo), and I can switch the output on the IVY to have the problem go to the left headphone side (so it is not the amp). I also did check the IVY to amp output wires and they seem to be in order. I think it is an issue on the IVY2, where I can measure a 4-50(!) mV voltage offset between ground and +/- on the right side. The beta22 will amplify this... which is not great for the headphones.
I decided on a IVYIII replacement and will post pictures when I get it all to working properly.
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If necessary you can AC couple to the beta22.
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