I have removed the USB
I have removed the USB pigtail/ ground loop on the computer... It did not help the sound. I was wrong. What was happening was the outside shell of the usb cable was making a bad/lossy connection to the port on the Mac Mini. So when I put the wire in between the two connectors it helped make a better connection. So now I have a new USB cable that is up to snuff and makes good contact. The addition of the ground loop to the new cable make the whole thing sound rather DIGITAL and unfocused.
But the looped grounds on the speakers are good.
Analog and Looped Grounds... Good
Digital and Looped Grounds... Bad
I have removed the USB pigtail/ ground loop on the computer... It did not help the sound. I was wrong. What was happening was the outside shell of the usb cable was making a bad/lossy connection to the port on the Mac Mini. So when I put the wire in between the two connectors it helped make a better connection. So now I have a new USB cable that is up to snuff and makes good contact. The addition of the ground loop to the new cable make the whole thing sound rather DIGITAL and unfocused.
But the looped grounds on the speakers are good.
Analog and Looped Grounds... Good
Digital and Looped Grounds... Bad
In my own experiments, adding loops to digital ground was a serious mistake. I was worried I had missed something when Phil reported the opposite, but thought I would wait and see what turned up, since I am used to being incorrect.
Thanks for that Marce, very nicely done. Do put some loops on your EnABL'd drivers though, and don't hesitate to put them on the other analog pieces of gear, that do not have a poured ground plane. And if just one of them has an actual circuit mirror ground plane, then it is very unlikely that anywhere but the speakers will be helpful.
Bud
Thanks for that Marce, very nicely done. Do put some loops on your EnABL'd drivers though, and don't hesitate to put them on the other analog pieces of gear, that do not have a poured ground plane. And if just one of them has an actual circuit mirror ground plane, then it is very unlikely that anywhere but the speakers will be helpful.
Bud
Hi Bud,
when I get chance I am going to give it a try, working 24/7 at the moment takes up all my time unfortenatly. Just by coincidence I am on a course for SI and such like for some new layout tools that we have got at work, to try and speed things up while controlling what is going on on the PCB to a greater degree.
Now this following tale I think you and hopefuly others will find of interest on the subject of listening tests, ability to measure etc.
We design communication systems at work, based around Bells midrange frequency range. Our systems have to work 100%, and have to be clear and audible in all situations, there is no deviation from this. We can measure just about anything, and do using a wide variety of very expensive equipement. But we still rely on listening tests for final quality tests etc of our designs. Because listening tests can be subjective we have set up a listening evoironment with a very (very) expensive head and torso model that mimics the humans binaural hearing ability. This gives us a listening test envoironment, where as well as real humans doing the listening we have a reference listener who dosn't have a bad day, gets colds or has a hangover when doing the tests. It also gives us a reference for collating what we here.
So even with ALL the measurement equipement and ability to measure to the nth level we still rely on EARS for the final assesment of our products.
when I get chance I am going to give it a try, working 24/7 at the moment takes up all my time unfortenatly. Just by coincidence I am on a course for SI and such like for some new layout tools that we have got at work, to try and speed things up while controlling what is going on on the PCB to a greater degree.
Now this following tale I think you and hopefuly others will find of interest on the subject of listening tests, ability to measure etc.
We design communication systems at work, based around Bells midrange frequency range. Our systems have to work 100%, and have to be clear and audible in all situations, there is no deviation from this. We can measure just about anything, and do using a wide variety of very expensive equipement. But we still rely on listening tests for final quality tests etc of our designs. Because listening tests can be subjective we have set up a listening evoironment with a very (very) expensive head and torso model that mimics the humans binaural hearing ability. This gives us a listening test envoironment, where as well as real humans doing the listening we have a reference listener who dosn't have a bad day, gets colds or has a hangover when doing the tests. It also gives us a reference for collating what we here.
So even with ALL the measurement equipement and ability to measure to the nth level we still rely on EARS for the final assesment of our products.
Okay everyone. Grab your socks. The following is a report from Dave Davenport, the brains behind Raleigh Audio and Rak Dac fame. Attached is a text file with his initial questions and my pseudo answers. I will admit to holding on to this document since mid year 2008, just in case Dave got far enough ahead of his business requirements to do the objective tests he has in mind and they are in his mind, not mine.
Hi Bud,
I have been experimenting with the loops that you sent me as well as some other things. I want to give you an interim report of my findings because prototypes for my new product came in from the assembler today so I will need to give that my attention this week and I am going on vacation next week so it will be a while before I can get back to the loops.
Since I use my system to evaluate products and changes to the products, I have voiced it to be very revealing, perhaps bordering a bit on the analytical. It has extremely high resolution and exposure of detail. As per you suggestion I chose to attach the loops in my system at the ground connection between the DAC board and the analog output board. This point is called “REF” for reference because I am very particular about separating the different grounds. The two boards have differential circuits which are connected together with five, 2” wires: a twisted pair (+/-) for each channel and a voltage reference (ground) for the differential signals. The REF is directly connected to a solid internal ground plane in the DAC board, which is 2.35” wide by 4.9” long. The loops were connected to the REF at the analog output board.
Here is a log of my experiments:
1. Attached a bare loop to the REF pad. There was a noticeable sonic result in two areas. First, it sounded like there was an increase in the upper midrange. (no attempt was made to measure this.) An example of the effect of this is a sharpening in the upper range of female vocals. Second, A slight smearing of the music was greatly reduced. I had not noticed this smear before and was evident only by comparing the sound with and without the loop. The effect was an increased coherence in the music.
2. I removed the loop. The sound returned to as it was originally.
3. I re-attached the loop to the REF pad. The results were as before.
4. Played music continuously for 19 hours. The change in coherence was the same as before the break-in period, however the upper midrange was still increased but not as much as before the break-in period.
5. I removed the loop. The sound returned to the original.
6. I attached the same bare loop to the same REF pad through an 8” piece of #20 Teflon insulated stranded wire. The sound was the same as that with the loop directly attached to the REF pad. (4. above)
7. I removed the bare loop and attached a cotton-shrouded loop to the REF pad. There was a noticeable result. There was the same increase in the coherence as with the bare loop, but without an apparent increase in the upper midrange.
8. Played music continuously for 24 hours. The coherence increased slightly.
9. I removed the loop. The sound returned to the original.
10. I prepared a copper plate by sweat-soldering a piece of 6” long, #20 Teflon insulated stranded wire to the center of the short side of a 10” x 4” x 0.025” copper sheet. I attached the wire to the REF pad. The copper plate was away from the electronics by the length of the 6” wire and lying flat on the top surface of a wooden cabinet. The electronics was mounted open on a glass plate by stand-offs. The glass plate was on the cabinet.
There was a noticeable result. The sound exhibited the same increase in coherence as with either of the loops when first attached. There was a slight apparent increase in the upper midrange, but less so than when the bare loop was first attached.
11. I wrapped the copper sheet in a single layer of a cotton terry cloth dish towel. There was a very subtle diminishment in the apparent increase in the upper midrange.
12. I left the towel on the sheet and played music continuously for 24 hours. The increased coherence was still present but there no longer was an apparent increase in the upper midrange.
13. I removed the towel from the sheet. There was a slight apparent increase in the upper midrange. This apparent increase was less than that with the bare copper plate before the break-in period.
14. I removed the plate and wire from the REF pad. The sound returned to the original.
End of report.
My general observation is that attaching copper to the REF increases coherence (reduces smear) and causes an apparent increase in the upper midrange. Applying a cotton shroud to the copper reduces or eliminates the apparent increase in upper midrange. There is a time, break-in, factor involved.
I must admit that I found myself shaking my head and laughing in disbelief several times, particularly when experimenting with the towel on the copper plate. However, I heard what I heard and will stand by that.
All for now, talk to you later,
Dave
Hi Bud,
I have been experimenting with the loops that you sent me as well as some other things. I want to give you an interim report of my findings because prototypes for my new product came in from the assembler today so I will need to give that my attention this week and I am going on vacation next week so it will be a while before I can get back to the loops.
Since I use my system to evaluate products and changes to the products, I have voiced it to be very revealing, perhaps bordering a bit on the analytical. It has extremely high resolution and exposure of detail. As per you suggestion I chose to attach the loops in my system at the ground connection between the DAC board and the analog output board. This point is called “REF” for reference because I am very particular about separating the different grounds. The two boards have differential circuits which are connected together with five, 2” wires: a twisted pair (+/-) for each channel and a voltage reference (ground) for the differential signals. The REF is directly connected to a solid internal ground plane in the DAC board, which is 2.35” wide by 4.9” long. The loops were connected to the REF at the analog output board.
Here is a log of my experiments:
1. Attached a bare loop to the REF pad. There was a noticeable sonic result in two areas. First, it sounded like there was an increase in the upper midrange. (no attempt was made to measure this.) An example of the effect of this is a sharpening in the upper range of female vocals. Second, A slight smearing of the music was greatly reduced. I had not noticed this smear before and was evident only by comparing the sound with and without the loop. The effect was an increased coherence in the music.
2. I removed the loop. The sound returned to as it was originally.
3. I re-attached the loop to the REF pad. The results were as before.
4. Played music continuously for 19 hours. The change in coherence was the same as before the break-in period, however the upper midrange was still increased but not as much as before the break-in period.
5. I removed the loop. The sound returned to the original.
6. I attached the same bare loop to the same REF pad through an 8” piece of #20 Teflon insulated stranded wire. The sound was the same as that with the loop directly attached to the REF pad. (4. above)
7. I removed the bare loop and attached a cotton-shrouded loop to the REF pad. There was a noticeable result. There was the same increase in the coherence as with the bare loop, but without an apparent increase in the upper midrange.
8. Played music continuously for 24 hours. The coherence increased slightly.
9. I removed the loop. The sound returned to the original.
10. I prepared a copper plate by sweat-soldering a piece of 6” long, #20 Teflon insulated stranded wire to the center of the short side of a 10” x 4” x 0.025” copper sheet. I attached the wire to the REF pad. The copper plate was away from the electronics by the length of the 6” wire and lying flat on the top surface of a wooden cabinet. The electronics was mounted open on a glass plate by stand-offs. The glass plate was on the cabinet.
There was a noticeable result. The sound exhibited the same increase in coherence as with either of the loops when first attached. There was a slight apparent increase in the upper midrange, but less so than when the bare loop was first attached.
11. I wrapped the copper sheet in a single layer of a cotton terry cloth dish towel. There was a very subtle diminishment in the apparent increase in the upper midrange.
12. I left the towel on the sheet and played music continuously for 24 hours. The increased coherence was still present but there no longer was an apparent increase in the upper midrange.
13. I removed the towel from the sheet. There was a slight apparent increase in the upper midrange. This apparent increase was less than that with the bare copper plate before the break-in period.
14. I removed the plate and wire from the REF pad. The sound returned to the original.
End of report.
My general observation is that attaching copper to the REF increases coherence (reduces smear) and causes an apparent increase in the upper midrange. Applying a cotton shroud to the copper reduces or eliminates the apparent increase in upper midrange. There is a time, break-in, factor involved.
I must admit that I found myself shaking my head and laughing in disbelief several times, particularly when experimenting with the towel on the copper plate. However, I heard what I heard and will stand by that.
All for now, talk to you later,
Dave
HI,is the same matter ?
from humblehomemadehifi
"The second tweak was to short the chassis of the driver to the minus pole of the connector. This is easily done by soldering a short piece of wire from the minus pole to the centre connection screw that holds the solder tab in place (see photo). This gave improved midrange clarity with a smoother treble and more punch in the bass – amazing for a 5-minute tweak that costs absolutely nothing!"
from humblehomemadehifi
"The second tweak was to short the chassis of the driver to the minus pole of the connector. This is easily done by soldering a short piece of wire from the minus pole to the centre connection screw that holds the solder tab in place (see photo). This gave improved midrange clarity with a smoother treble and more punch in the bass – amazing for a 5-minute tweak that costs absolutely nothing!"
An externally hosted image should be here but it was not working when we last tested it.
Yes, it is very similar.
Had the chassis been protected with an electro tin coat it would have been identical. This was very often done in the 30's through 50's and provided the portion of ground plane that the electron pools provide.
I do not push it because there is simply no way to tell how good the chassis of any individual driver is going to be. It is often a very good idea to provide the dielectric benefits that the EP's with plastic and cotton outer casing provide, especially with EnABL'd drivers with their extended resolution. This combination just allows a much finer grain of control, over the benefits of having a ground plane out at the driver.
Bud
Had the chassis been protected with an electro tin coat it would have been identical. This was very often done in the 30's through 50's and provided the portion of ground plane that the electron pools provide.
I do not push it because there is simply no way to tell how good the chassis of any individual driver is going to be. It is often a very good idea to provide the dielectric benefits that the EP's with plastic and cotton outer casing provide, especially with EnABL'd drivers with their extended resolution. This combination just allows a much finer grain of control, over the benefits of having a ground plane out at the driver.
Bud
BudP thanks !
HI Soongsg you mean to run a separate wire from basket to negative amp speakers out ?
es. with supra ply4s we can do this and plus isolate the wire form RFI
plus BudP tricks!
HI Soongsg you mean to run a separate wire from basket to negative amp speakers out ?
es. with supra ply4s we can do this and plus isolate the wire form RFI
An externally hosted image should be here but it was not working when we last tested it.
plus BudP tricks!
Re: Okay everyone. Grab your socks
The report by Dave Davenport peaked my curiosity to experiement with a cotton sleeve on the loops. I did not have any cotton shoe laces big enough, so I tried slipping on some loose fitting nylon weave over the tails atttached to the neg side of my speakers and amp output.
Wow, immediately killed the dynamic airy sound. So I pulled them off and immediately the sound was back. I figured it was the nylon dielectric causing the big change.
I took some strips of light cotton fabric from an old T shirt and wrapped it loosely around the traps. Instantly the same negative impact. I was tempted to leave it in place for a couple of hours to see if there was a break in factor, but I could not stand hearing my system so obviously compromised. I removed the cotton and back came the open sound and dynamics.
I had earlier thought that the tails sounded better when surounded by air. If they lie tight against another surface, some of the open sound is compromised.
My conclusion is, leave the cotton off. Keep the wire free and clear and you will get quite dramatic improvement.
Perhaps its worth noting that my speaker cables do not have a lot of shielding and I keep them suspended off the floor as it has a similar all be it not so dramatic effect on the open airy sound.
The report by Dave Davenport peaked my curiosity to experiement with a cotton sleeve on the loops. I did not have any cotton shoe laces big enough, so I tried slipping on some loose fitting nylon weave over the tails atttached to the neg side of my speakers and amp output.
Wow, immediately killed the dynamic airy sound. So I pulled them off and immediately the sound was back. I figured it was the nylon dielectric causing the big change.
I took some strips of light cotton fabric from an old T shirt and wrapped it loosely around the traps. Instantly the same negative impact. I was tempted to leave it in place for a couple of hours to see if there was a break in factor, but I could not stand hearing my system so obviously compromised. I removed the cotton and back came the open sound and dynamics.
I had earlier thought that the tails sounded better when surounded by air. If they lie tight against another surface, some of the open sound is compromised.
My conclusion is, leave the cotton off. Keep the wire free and clear and you will get quite dramatic improvement.
Perhaps its worth noting that my speaker cables do not have a lot of shielding and I keep them suspended off the floor as it has a similar all be it not so dramatic effect on the open airy sound.
Yes, I have shink wrap on the loops. The loops are 5" in length, 140 loops of 34guage copper magnet wire. There are 3 shrink wraps of 1/2 inch ea. 2 are slit and one partially slit. The only other loop in the system is pure silver on the ground plane of the DAC source. The ground on each amp channel is attached to a 1/2 inch thick plate of copper used for heat sink.
Alex
I would plug one into the (I assume) mixing board at one of the outputs or perhaps into the return of one of the external loop mix circuits.
For the powered items I would apply one to each driver. You can skew the "aid" these things provide by how long a piece of shrink tube you use, for a given length of wire. 2.5mm of unslit tube in 3 places will do a very good job above about 2k Hz, when applied to 150 mm of Litz. For the Bass augmentation I would go looking for the somewhat thicker walled tube that has a glue layer on the inside of the tube and might get out to 37.5 mm in tube length, with the usual slit ratios. Lengths of this sort can begin to smear the transients, so approach with caution. For a mid driver, especially a cone mid, I would use the standard loop and slit tube ratio.
wlowes
As for the loss of air with woven tubing....hmmmmmm. I do notice a very slight softening of edges, a move from tone and meter to timbre and emphasis portrayal, when the cotton is added, but never a loss of air. I have noticed some very drastic changes when using other woven materials though. Due to this, none of my speaker cables or interconnect cables, even the digital connection to my outboard DAC, have any sort of woven shield. Just one or two strands of Litz, with periodic application of shrink tube, in two separate cotton tubes is the norm. Interesting that I can parallel a power cable with any of them and pick up zero hum.
Obviously, if a cotton tube doesn't work for you leave it off, but it should be quite good at retaining those tiny, wide band signals that describe room space and...air. So, I am a bit confused.
Bud
I would plug one into the (I assume) mixing board at one of the outputs or perhaps into the return of one of the external loop mix circuits.
For the powered items I would apply one to each driver. You can skew the "aid" these things provide by how long a piece of shrink tube you use, for a given length of wire. 2.5mm of unslit tube in 3 places will do a very good job above about 2k Hz, when applied to 150 mm of Litz. For the Bass augmentation I would go looking for the somewhat thicker walled tube that has a glue layer on the inside of the tube and might get out to 37.5 mm in tube length, with the usual slit ratios. Lengths of this sort can begin to smear the transients, so approach with caution. For a mid driver, especially a cone mid, I would use the standard loop and slit tube ratio.
wlowes
As for the loss of air with woven tubing....hmmmmmm. I do notice a very slight softening of edges, a move from tone and meter to timbre and emphasis portrayal, when the cotton is added, but never a loss of air. I have noticed some very drastic changes when using other woven materials though. Due to this, none of my speaker cables or interconnect cables, even the digital connection to my outboard DAC, have any sort of woven shield. Just one or two strands of Litz, with periodic application of shrink tube, in two separate cotton tubes is the norm. Interesting that I can parallel a power cable with any of them and pick up zero hum.
Obviously, if a cotton tube doesn't work for you leave it off, but it should be quite good at retaining those tiny, wide band signals that describe room space and...air. So, I am a bit confused.
Bud
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