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sandston

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  1. Id be curious to see how it stacks up against the MiniDSP SHD studio. A bit more expensive at $899 but you get Dirac built in and the Studios is all digital and takes an outboard (ie: upgradeable) power supply. Frankly I am quite surprised this Volumio streamer isn't getting way more traction in the forums here. I mean come on we all have great DACS here on this website.
  2. No to be clear they did not. They said they were able to reproduce the noise and that they were working to determine the cause. In the meantime they are sending me a work around fix in the form of a Y-Cable. I am assuming they have created a filter in this cable. Again kudos to them for being forthright on this. You would not get this from most companies in my experience. I also want to add that their customer service throughout this whole issue has been exemplary.
  3. Thank you One and a Half for taking the time to absorb all the details so far regarding this noise. I have tried cheater plugs and moving the power of the subs, preamp and amps off the P10 in every conceivable combination. I also turned off every light and went so far as to shut off all the circuits in my house except the one feeding my stereo. These were some of the first things I tried. It is pretty obvious at this point that this is noise generated from the Sub amps. To your question, when I turn the subs off the noise continues for about 10-20 seconds until what appears to be the caps in the sub amps power supply completely discharging. When this happens we hear a small squeal and a spike and then silence. Meanwhile SVS has been able to recreate the problem on their end (Kudos to this company for their customer service and honesty by the way) They are sending me a patch cable that they have made that has fixed the issue in their tests. I can only assume this includes some type of filter they have devised. I thought of trying the same thing and have looked at the Jensen filters and the less expensive inline rca crossover filters available on parts express to see if they would eliminate the noise by effectively crossing over the upper frequencies. My guess is they would mask the noise to some degree but this seems to be a band aid approach. I think we would all agree that the the fix should occur at the power supply leak not in the signal path.
  4. have tried with and without the Regen unit.
  5. All the power is pretty clean. The whole system is plugged into a PS Audio P10 .
  6. These are tube amps (Melody 845M) and there is a of course a certain amount of noise present in the speakers when you are close to them. Always will be from what I understand. This noise is not audible from more than a couple feet from the speaker. I'm sure there are more accurate ways of measuring the squealing noise that is happening however I wanted to post this to see if anyone recognized the pattern. It is apparent to me that the subs alone are creating this noise and that it is not an interaction between components. There appears to be some type of electronic leakage on the inputs of this amps design. I have been talking extensively with SVS and they claim that they have never seen this phenomenon. They are going to try to recreate it now with by running an RCA from the input of the sub into an AVR with the volume all the way up.
  7. I was measuring it a few inches from the speaker but the squeal can be heard from my sitting position.
  8. Still no luck with mitigating the squeal attached are two screen shots showing a frequency screen grab with the sub on and the sub off. No squeal seems to be noise a several regularly spaced frequencies. I also substituted an A/V unit I had and plugged the sub input into one of the inputs on the AV unit and the squeal can still be heard with the volume turned all the way up.
  9. I was thinking the same thing. Below is a diagram showing the layout with the preamp in the mix. To recap there are two subs and two monblocks for the mains. The squeal occurs on both channels and is isolated on each channel. When the output pots on the preamp are zeroed out the squeal disappears. The level of the squealing is always constant. The preamp does not need to be turned on for this to happen. The volume and the input pots on the preamp do not effect the squealing sound at all. The subs have stereo in and a high pass stereo out. If I remove the preamp from the mix entirely and hook the monoblocks up to the high pass output of the sub the squeal is still there. I think its pretty evident the squeal originates in the subs. Somehow the topology of the output of the preamp is canceling the noise out. By what electrical means I cannot say. I am wondering if there is some type of filter that would mitigate this noise and not effect the quality of sound in the subs? I should probably just return the subs but I really like the quality of the sound of these and I really like the control app that SVS has developed. I have included input sensitvities and impedance numbers for the various stages on the drawing as well as a few relevant photos of the preamp and subs for those who are more circuit curious. I have been trying Peters parallel ground suggestion but have not yet found a point between the units that mimics the effect of turning the output pot to zero. The chassis of the preamp appears to be completely isolated from the circuit so I need to open my unit up to get a common ground point in the preamp. The attached photo of the preamp attached shows the outputs in the lower left corner. My unit has four outputs and no headphone jack. The resistors that make up the "Summing Circuit" to the mono sub output on this unit are not present in my unit. Again thanks again for taking the time on this with me.
  10. Peter I appreciate you kicking the can around with me on this. To be clear the squealing happens with the preamp out of the equation. If I detach the preamp and hook the amps to the line level output on the sub I get the same squeal as when the amps are hooked to the input of the sup via the preamp. One of two things I have found that stops the squeal is when I turn the output voltage level pot to zero on the preamp. In this preamp the output signal goes through this pot and is then split to two RCA outputs. No circuitry between the pot and the outputs. Think of a simple y-cable. The pot does not sit between the RCA outputs. When the pot is turned to zero the squealing stops which makes me think this might somehow shunt the noise to ground. However this is beyond my technical knowledge of circuits. I will test the idea of the parallel ground wire as this would be recreating the shut to ground scenario.
  11. Peter Thanks for jumping in so quickly and taking the time to help out. To answer your first question. The subs power cords do have a three prong cord with ground. The subs do not have a high level input. The have a left and right low level input and a left and right high pass output that allows one to run their amp off the sub to take advantage of the dsp crossover. I do not intend to use this in my setup as I do not want an A/D/A conversion above 80 hertz. However I do get the squealing noise from my mains if my amps are looped through the subs or if they share a line level signal. I have two of these subs and monoblock amps and in both instances they create the same squealing noise. The level or pitch of the squealing noise is unaffected by any changes I make on the sub control panel (Volume, polarity, phase etc.) The only thing that has mitigated the squeal is putting the DSpeaker unit between the sub and the preamp and when I do have both the subs and the monoblocks connected to the preamp and I turn the output levels all the way down the noise disappears. This happens whether or not the preamp is powered on or not. My preamp (Decware CSP2+) has input and output trim pots as well as a volume control. The volume knob and the inputs trim pots have no effect on the squealing noise. Do you know if a potentionmeters ground is lifted when turned all the way down? This does seem to point to some type of grounding issue.
  12. I am desperartely seeking help on some system noise I started encountering with the addition of two new SVS SB4000 subwoofers into my system. I replaced two older subwoofers( Elac debut 12 and a Cadence CSX-12). The new SVS subwoofers seem to be injecting a high pitch squealing noise that is coming out of my mains. My system consists of a Decware CSP2+ preamp with two output per channel. My amps are monoblock Melody 845-1 tube units. I have gone through all the possibilities with SVS and they agreed to send me new amps to replace the ones that came with the units. The new amps create the same squealing noise. To give some additional background when I turn the preamp off the noise still is present in the mains. The high pitch squeal is not effected by changes in volume. The sound appears to be emanating from the SVS subwoofers amplifiers. My typical mains are 94db efficient but its still audible in some 86db speakers I own. The Decware CSP2+ preamp has output level controls. One for the left and one for the right channel. It effects both R and Left line level outputs equally. With the preamp turned off when I turn the output levels all the way all the way down the squealing stops in the corresponding channel which seams that the noise may be being shunted to ground....maybe. This points to some possible grounding issue within the preamp...possibly? However if I plug the mains amps directly into the subs high pass output which removes the preamp from the system I still get the squealing sound. This did not happen with my other subwoofers. The other thought is that is some type of impedance mismatch happening between the tube amps and the solid state amps being on essentially a Y-Splitter at the preamp. I currently put a DSpeaker unit between the subs and the preamp and this essentially blocks the noise however I would prefer not to have this additional A-D-A stage in my system. I have tried cheater plugs on both units to try to isolate a ground loop to no avail. The SB-4000 subs have DSP and im wondering if this is some unchecked digital noise leaking into the system.I know this might not be the website forum for this but I am thinking more and more that this is a digital related noise so I thought I might look here for advice. Any thought wisdom or advice from the community would be appreciated. Has anyone come across this phenomenon? I would really like to keep these subs in my system but before I move on I would like to have an idea of what is happening so I can avoid this moving forward. I am happy to provide input and output impedance numbers for the units if somebody feels this might help. Thanks for any help or advice in advanced.Regards,Steve C
  13. I would agree that unplugging a unit from the wall would eliminate the potential of noise leakage. The 1400 and 3000 series have a wifi program that allows you to control the unit remotely. Id be curious to know if that includes a physical decoupling from the mains power source.
  14. Did a little more research and it looks like output impedance is a concern with lithium batteries versus an ultra capacitor. Would this be a limiting factor in trying to apply a whole system litium battery approach?
  15. I recently read this article on enjoythemusic.com by Tom Lyle and it has me incredibly intrigued. In short the article gives a review of the improvements made by powering the authors front end using a GoalZero Lithium Ion Battery pack. https://headphone.guru/goal-zero-yeti-400-lithium-portable-power-station-review-by-enjoy-the-music-com/ https://www.amazon.com/Goal-Zero-Portable-Generator-Alternative/dp/B07CRQX9KW/ref=sr_1_4?s=lawn-garden&ie=UTF8&qid=1546723009&sr=1-4&keywords=goal+zero+lithium To be honest I am a lurker here for certain and I must say I envy and thank all the contributors here whose technical knowledge and testing make this site such an amazing resource. What I have learned here is that clean power plays a vital role in the audio path. I have also learned that its so incredibly complicated in practice. So I'm curious what the community thinks of this approach. My system includes an Uptone LPS-1 power supply. This appears to be one of those items that everyone seems to agree on when it comes to sonic improvements. So of course why not power ones whole system with batteries? Cost seems like the obvious answer but perhaps maybe not. I also own a PSaudio P10 power plant. This replaces a home brew balanced power supply and did wonders to lower the noise floor of my mostly tube based system. Both of these investments have provided improvements to the quality of sound in my system so the subject of clean power has really intrigued me. However looking at the cost per watt of of clean power I cant help be intrigued by the thought of using a large lithium battery back for the whole system. As a comparison the PSaudio Directstream 15 which produces 1500 watts of continuous power and sells for $7500 does this at a cost of $5 a watt. The PSaudio P10 (not the current version) which has no shortage of accolades can be picked up for around $2500 used. The P10 delivers 1500 watts of pure sine wave power for $1.66 a watt. The GoalZero 1500 Lithium creates the same watts of continuous power for $1.20 a watt, and the GoalZero 3000 can provide 3000 watts for $1 a watt. Now I dont pretend to know if this is an apples to apples comparison of power nor do I want to launch into a debate over the PSaudio approach is a good approach to powering ones system. What intrigues me is whether or not powering a whole system or at least the front end this way is a path to explore. Tom Lyle at Enjoythemusic seems to think so. I remember reading somewhere in a discussion about supercapacitor power provides "cleaner" power compared to lithium. Perhaps something to do with ripple ? I dont know I dont recall. I'm curious what the more educated members here think. I am also curious if this unit remains plugged in while in use does leakage effect sound quality? On the subject of leakage would several smaller units be better than one large unit? GoalZero also claims their output in in the form of a pure sinewave as opposed to what they term a modified sine wave which they claim is better for sensitive electronics. The comparisons to PSaudios approach seem obvious here. I would really enjoy the communities thoughts on this approach.
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