Yes, I was joking.
Hoever,I agree there are a lot of biologies, brain processing and adaptations in play. Our eyes accommodate, so why not the ears since many of the reflexes are connected?
I think you are hearing differently after five/thirty/sixty minutes just based on your ears and brain adjusting.
I have in fact gone to listening sessions and had my stapedius go into fast mode spasm, it's a weird burring, so I take ear protection when going to demos now.
Hoever,I agree there are a lot of biologies, brain processing and adaptations in play. Our eyes accommodate, so why not the ears since many of the reflexes are connected?
I think you are hearing differently after five/thirty/sixty minutes just based on your ears and brain adjusting.
I have in fact gone to listening sessions and had my stapedius go into fast mode spasm, it's a weird burring, so I take ear protection when going to demos now.
I developed tinnitus about 15 years ago. Perhaps due to an ischemic episode or perhaps simply due to aging. This put the brakes on high end audio for years. I was jaded. But then, I thought, all right, somehow, I will make the best of it. My tinnitus waxes and wanes. I have not determined what control I may have. Nonetheless, I sometimes have relief and then I listen to music. The XA25, unlike my previous hardware, is so comfortable to listen, that I can listen to it and mask my tinnitus. Thus, once again, I am able to enjoy music. However, I am hesitant to crank the volume for fear of evoking my tinnitus.
Although the field of neuroscience has become so broadly defined as to lose all meaning; a neuroscientist is supposedly what I am. Thus, I am interested in the biological adjustments to distortion and musicality. Thank you for sharing your thoughts.
Although the field of neuroscience has become so broadly defined as to lose all meaning; a neuroscientist is supposedly what I am. Thus, I am interested in the biological adjustments to distortion and musicality. Thank you for sharing your thoughts.
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What I find remarkable about the XA25 is that with very high open-loop gain it is stable without any frequency compensation other than that from the device gate capacitances and the input filter.
The July 2017 6Moons review 6moons audioreviews: Pass Labs XA25 show the addition of an output Zobel, which papa says probably isn't really needed: F4 Beast Builders.
The July 2017 6Moons review 6moons audioreviews: Pass Labs XA25 show the addition of an output Zobel, which papa says probably isn't really needed: F4 Beast Builders.
A neuro-scientist with tinnitus, somewhat ironic.
As of three months ago, I'm under the umbrella of a psychiatrist, the only drugdealer willing to prescribe 7/7 sleep medication for the worst case of tinnitus.
Were you surprised about the stability of the XA25 with no degeneration, which resulted in very high open-loop gain?
No. The open loop gain is lower than the sims suggest because they
don't represent the details of the actual circuit. In the XA25 I can set the
open loop figure easily and arbitrarily.
I haven't used frequency compensation (or output zobels) in PL or FW
product for many years. But the XA25 is new, and being a belt and
suspenders kind of guy, I put the output zobel on the XA25 just as
cheap insurance.
don't represent the details of the actual circuit. In the XA25 I can set the
open loop figure easily and arbitrarily.
I haven't used frequency compensation (or output zobels) in PL or FW
product for many years. But the XA25 is new, and being a belt and
suspenders kind of guy, I put the output zobel on the XA25 just as
cheap insurance.
Years of high levels gave me tinnitus in the left ear, I can hear it whenever I focus on it, at first I was extremely depressed thinking that I would have tinnitus for the rest of my life, how will I ever sleep again with that ringing in my ear? will I enjoy music ever again?.
After some years I realized that my hearing is quite good aside from that constant 8KHz tone, I believe most people have tinnitus, specially those of us living in urban areas, but only those with a trained ear realize it or at least care so much about it. Anyway, the best cure I could find is resignation/acceptance, If you just ignore it, then it is not that bad. The more you think about it, the more it rings. I've tried anti-tinnitus pills and similar cures, none of them worked for me.
Nowadays I keep my volume at a more civilized level most of the time.
XA25 Chassis Ground Point
The XA25 is so much darker that my previous hardware that I have become more sensitive to background sounds - kitchen fan, clocks, HVAC, etc. My 20A Equitech power conditioner has a huge torroidal transformer that sometimes produces an audible hum from the listening position, but not always. There does not appear to be anything loose.
I monitor line voltage with a old Audio Power Conditioner. The mains sometimes slip into 2-5V fluctuations that causes some LED ceiling lights to flicker. These fluctuations are present on all house circuits so I imagine they are coming through the main feed. This may go on for several hours and then quit for a few weeks. I have not yet contacted the power company. The Equitech becomes more audible during these times.
I am still building/tweaking the HPA-1/XA25 rack, points, cabling etc. I recently noticed an audible hum in the listening room when the Equitech was not being used. My heart sank. I have spent decades troubleshooting 60 cycle hum in laboratory environments. I did not want to go after it in my house. Plus, I recently built custom interconnects and power cables. I feared that I messed something up.
I started tearing everything down and simplifying the system. Over the course of a day, I got nowhere. I continued to simplify the system. Eventually, I killed the circuit breakers to the wall receptacles and ceiling lights. I still had hum coming from the mid-range drivers. I disconnected the speaker cables from the XA25. There was still hum coming from the mid-range. I disconnected the speaker cables from the speaker. The speaker quit humming. Alright, the speakers cables were enough of an antenna to drive the mid-range. That surprised me because I figured they would find a ground shunt through the XA25. The speakers had been bi-wired. I replaced the bridges across the +/- terminals. Now the speakers hummed without the speaker cables attached. Remove the bridges, they go silent. There must be enough unshielded wire inside the cabinets that, with the bridges in place, there is an antenna to drive the mid-range with 60 cycle hum.
All right, I could ignore this. I don't typically listen to quiet passages with my ear inside the mid-range. Nonetheless, I would like to get rid of this hum. And do so without wrapping my speakers in tinfoil.
Sorry for that long introduction. It could have been much longer if I went through all of the testing I did before I realized that the electronics were not directly involved. Here is my question. There are, on the rear panel of the XA25, two hex bolts located on either side of the negative speaker posts. Are these intended for chassis ground points? Or, if I loosen them, is something going to fall apart inside the XA25?
The XA25 is so much darker that my previous hardware that I have become more sensitive to background sounds - kitchen fan, clocks, HVAC, etc. My 20A Equitech power conditioner has a huge torroidal transformer that sometimes produces an audible hum from the listening position, but not always. There does not appear to be anything loose.
I monitor line voltage with a old Audio Power Conditioner. The mains sometimes slip into 2-5V fluctuations that causes some LED ceiling lights to flicker. These fluctuations are present on all house circuits so I imagine they are coming through the main feed. This may go on for several hours and then quit for a few weeks. I have not yet contacted the power company. The Equitech becomes more audible during these times.
I am still building/tweaking the HPA-1/XA25 rack, points, cabling etc. I recently noticed an audible hum in the listening room when the Equitech was not being used. My heart sank. I have spent decades troubleshooting 60 cycle hum in laboratory environments. I did not want to go after it in my house. Plus, I recently built custom interconnects and power cables. I feared that I messed something up.
I started tearing everything down and simplifying the system. Over the course of a day, I got nowhere. I continued to simplify the system. Eventually, I killed the circuit breakers to the wall receptacles and ceiling lights. I still had hum coming from the mid-range drivers. I disconnected the speaker cables from the XA25. There was still hum coming from the mid-range. I disconnected the speaker cables from the speaker. The speaker quit humming. Alright, the speakers cables were enough of an antenna to drive the mid-range. That surprised me because I figured they would find a ground shunt through the XA25. The speakers had been bi-wired. I replaced the bridges across the +/- terminals. Now the speakers hummed without the speaker cables attached. Remove the bridges, they go silent. There must be enough unshielded wire inside the cabinets that, with the bridges in place, there is an antenna to drive the mid-range with 60 cycle hum.
All right, I could ignore this. I don't typically listen to quiet passages with my ear inside the mid-range. Nonetheless, I would like to get rid of this hum. And do so without wrapping my speakers in tinfoil.
Sorry for that long introduction. It could have been much longer if I went through all of the testing I did before I realized that the electronics were not directly involved. Here is my question. There are, on the rear panel of the XA25, two hex bolts located on either side of the negative speaker posts. Are these intended for chassis ground points? Or, if I loosen them, is something going to fall apart inside the XA25?
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Thank you. At the moment, my speakers cables are biwired with four runs of instrument cable. The shields are floating. I knew that was a bad idea but I did not want to complicate the connections. I may rig up some ground wires from the shields at the XA25 end and see if there is any benefit to single ended grounding of the shields to chassis and go from there. The hum is so slight that this is mostly an academic exercise. The hum is only audible with my ear less than 6" from the driver. As I wrote earlier; my speakers hum just sitting there with no connections. The 200 Amp feed line enters the house adjacent to the listening room. Powering the XA25 with the speakers cables connected increases the hum by very little. Thanks again for the information.
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Aerial 7B. As I said, this is largely academic. The hum is only there if you go looking for it. There is mechanical hum from the toroidal transformer of my Equitech 20A conditioner that can be heard from a few feet. The speaker hum can only be heard from less than six inches from the driver. With the XA25 noise level at only 50 microvolts, I would prefer dead silence; but this may not be obtainable. The Equitech is the bigger fish, but there is no way to fry it. This is mostly an academic "problem." The system is absolutely stunning to listen to. I do not hear hum from the listening position.
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Do you have light dimmers in your listening room or other rooms?
Could be DC on your AC line.
I have built two Balanced Power Units (BPU). One uses a 2000VA toroid and another uses 1500VA toroid.
In the 2000VA BPU, I installed a DC filter on the AC line. In the 1500VA BPU I did not install a DC filter.
The 1500VA unit has a hum and the 2000VA unit does not have a hum. There is a momentary hum when switching on devices, but then subsides rapidly.
Equi=tech is probably one of the best at what they do. No doubt they have such filtering, so maybe something in the Equi=Tech is going bad?
Just a thought.
Vince
Could be DC on your AC line.
I have built two Balanced Power Units (BPU). One uses a 2000VA toroid and another uses 1500VA toroid.
In the 2000VA BPU, I installed a DC filter on the AC line. In the 1500VA BPU I did not install a DC filter.
The 1500VA unit has a hum and the 2000VA unit does not have a hum. There is a momentary hum when switching on devices, but then subsides rapidly.
Equi=tech is probably one of the best at what they do. No doubt they have such filtering, so maybe something in the Equi=Tech is going bad?
Just a thought.
Vince
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