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Post by brucew268 on Oct 23, 2023 21:36:59 GMT
Some Balanced Mains The last couple weeks, I’ve been listening more around 9.30-10.00pm than my usual at 5.00pm and noticing significantly better sound. Then I remembered that I have a balanced mains that I built several years ago in an attempt to equalise daytime listening with late evening listening, but it has been languishing in another room since I moved the HiFi to my home office. Today I plumbed it in and had a listen. It seems to be about ½ to 2/3 of the late evening sound which is encouraging and yet there were some problems. No dynamics. The sound floor is not at low as it should be. Some of the higher frequencies are a bit dull. Dynamics & FrequenciesWhile considering whether the transformer is underpowered, I remembered that the front plate of the steel enclosure has a 100x100mm SilentCoat treatment in its centre. Removing that, the dynamics returned but there was a good bit of glare and congestion. After playing a bit, I settled on a 35mm disc in the corner of the front panel and also the back panel. Closer, but I often find that damping is not frequency-precise enough. Some frequencies and presentation are improved but other frequencies sound unnaturally dulled. So maybe the answer is a different enclosure. The current one is steel 300 x 300 x 200, and maybe the steel is just a poor choice for ringing and damping?
I could use 300-350h x 200-250w x 120-150d but needs to be strong enough to hold a 20kg transformer mounted vertically to its back plate. Somehow ABS or PVC don’t seem likely candidates though they’d be good for resonance? So perhaps aluminium. If ABS or Polycarb or PVC, I could use 300-350w x 230-260d x 120-180h if it will manage 20kg inside. Otherwise would still need aluminium. I haven’t yet found any enclosures I feel confident about and those prices sure are a lot higher than the electrical box I’m currently using. Sound FloorCurrently I’m using a simple NTC thermistor to handle inrush current. But because it is a resistor might it be introducing noise to the mains? Would a softstart circuit be a better choice? Options? Also the wires and DC blocker are currently above the transformer mounted to the bottom plate so likely being affected by its RF field. Redoing the format so circuits to the side might improve the noise floor too.  2023-10-23_10-31-02 by Bruce Warren, on Flickr |
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Post by brucew268 on Oct 23, 2023 21:43:25 GMT
Maybe this if it could handle the weight. |
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Post by brucew268 on Oct 31, 2023 11:29:51 GMT
After a couple days of settling in, the balanced mains unit really sounded great. So much more sense of flesh and body to the instruments and greater sense of inhabiting the space of my listening room. So good, that I was a little afraid to make any changes. But I did want to make a few changes which should only improve things:
- replace the thermistor with an actual soft start module that would switch the thermistor out of the path after a couple seconds.
- move the transformer from the 200x300mm (side) panel to the 300x300mm (back) panel so that wires could be more easily out of the transformers RF field
- Maybe turn the box onto its back so that the transformer stays on the bottom of the chassis.
I made those changes this weekend and was quickly sorry. The magic of the last few days was no longer there. I'm letting things settle a day or two since the changes involved a new bridge rectifier on the DC blocker and a new film capacitor on the soft start module. The original cap came broken off due to being shipped in a padded envelope rather than a box. Of course the resonant properties of the enclosure are rather different with the transformer mounted to a different sized panel as well.
My back and legs were also a bit sorry, as the transformer is 20kg and went up and down the stairs a few times not to mention from floor to desk a few times.
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Post by brucew268 on Nov 6, 2023 21:29:15 GMT
Given 100 hours of burn-in with the soft start board installed and the transformer moved to a different panel -- the soundstage returned for wide and spacious room inhabiting sound. But the dynamics and bass were not as good as prior to the reconfig, and the frequencies around strings were slightly dull, only noticeable at points. I’ll take it in a few steps to get back where I was:
• Last weekend I replaced the soft start board with the bare thermistor from before. Wow...simply unreal performance on so many aspects... It's almost like the system is full of those hologram projectors in Star Wars, and sound is appearing and floating in front of you. It's quite extraordinary and certainly unlike anything that has come before it. The detail too is beyond the realms of any xxxx I have tried. When I read Oli’s description here, it sounded like he’d been listening through my balanced mains transformer! With the soft start board gone, the dullness is gone and fine details, sparkle, textural depth of the bass are all stellar now, and soundstage is in a whole different league than before… though it took 6+ hours to show up after powering back up after the rewire. I’m not sure what would cause that, maybe an issue endemic to huge balanced toroidal transformers? I do find that there is so much detail that I have to get used to it. I keep thinking the high frequencies must be rather tipped up to get this amount of detail across the spectrum, but the quick and dirty recorded spectrum chart doesn’t show anything obvious. It will take further listening to be sure and playing with SilentCoat discs is giving mixed results so far. • I may move the feet back to the smaller panel and move the box to a vertical orientation. More listening required first. • Might also move the transformer back to the now-bottom smaller panel. |
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Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 16,109
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Post by Bigman80 on Nov 7, 2023 6:39:04 GMT
Given 100 hours of burn-in with the soft start board installed and the transformer moved to a different panel -- the soundstage returned for wide and spacious room inhabiting sound. But the dynamics and bass were not as good as prior to the reconfig, and the frequencies around strings were slightly dull, only noticeable at points. I’ll take it in a few steps to get back where I was:
• Last weekend I replaced the soft start board with the bare thermistor from before. Wow...simply unreal performance on so many aspects... It's almost like the system is full of those hologram projectors in Star Wars, and sound is appearing and floating in front of you. It's quite extraordinary and certainly unlike anything that has come before it. The detail too is beyond the realms of any xxxx I have tried. When I read Oli’s description here, it sounded like he’d been listening through my balanced mains transformer! With the soft start board gone, the dullness is gone and fine details, sparkle, textural depth of the bass are all stellar now, and soundstage is in a whole different league than before… though it took 6+ hours to show up after powering back up after the rewire. I’m not sure what would cause that, maybe an issue endemic to huge balanced toroidal transformers? I do find that there is so much detail that I have to get used to it. I keep thinking the high frequencies must be rather tipped up to get this amount of detail across the spectrum, but the quick and dirty recorded spectrum chart doesn’t show anything obvious. It will take further listening to be sure and playing with SilentCoat discs is giving mixed results so far. • I may move the feet back to the smaller panel and move the box to a vertical orientation. More listening required first. • Might also move the transformer back to the now-bottom smaller panel. I had mixed results from BMUs. The one Alan and I built was certainly excellent, but later when I started to fit EMI/RFI filters into the IECs of all my kit, it didn't work anymore. Squashing dynamics, sounding midband heavy and losing any sparkle or light touch in the HF. When I took it out, the system became better for it. I use it on the lash up in the garage now and it made a noticeable and appreciable difference...no filters. Mains is a funny beast. The only thing I have found to be consistent is the fact that mains cables seem to sound better when unshielded. That required some careful routing and super short lengths, but so far that's been the sweet spot. Unshielded mains cables and IEC RFI/EMI filters...not what the forum experts would prescribe ! Enjoying the thread Bruce 👍 |
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Post by brucew268 on Nov 7, 2023 8:53:12 GMT
Given 100 hours of burn-in with the soft start board installed and the transformer moved to a different panel -- the soundstage returned for wide and spacious room inhabiting sound. But the dynamics and bass were not as good as prior to the reconfig, and the frequencies around strings were slightly dull, only noticeable at points. I’ll take it in a few steps to get back where I was:
• Last weekend I replaced the soft start board with the bare thermistor from before. When I read Oli’s description here, it sounded like he’d been listening through my balanced mains transformer! With the soft start board gone, the dullness is gone and fine details, sparkle, textural depth of the bass are all stellar now, and soundstage is in a whole different league than before… though it took 6+ hours to show up after powering back up after the rewire. I’m not sure what would cause that, maybe an issue endemic to huge balanced toroidal transformers? I do find that there is so much detail that I have to get used to it. I keep thinking the high frequencies must be rather tipped up to get this amount of detail across the spectrum, but the quick and dirty recorded spectrum chart doesn’t show anything obvious. It will take further listening to be sure and playing with SilentCoat discs is giving mixed results so far. • I may move the feet back to the smaller panel and move the box to a vertical orientation. More listening required first. • Might also move the transformer back to the now-bottom smaller panel. I had mixed results from BMUs. The one Alan and I built was certainly excellent, but later when I started to fit EMI/RFI filters into the IECs of all my kit, it didn't work anymore. Squashing dynamics, sounding midband heavy and losing any sparkle or light touch in the HF. When I took it out, the system became better for it. I use it on the lash up in the garage now and it made a noticeable and appreciable difference...no filters. Mains is a funny beast. The only thing I have found to be consistent is the fact that mains cables seem to sound better when unshielded. That required some careful routing and super short lengths, but so far that's been the sweet spot. Unshielded mains cables and IEC RFI/EMI filters...not what the forum experts would prescribe ! Enjoying the thread Bruce 👍 Cheers. It's always interesting that not everyone gets the same result from someting due to the myriad of differences between systems and contexts.
Yeah, I left the Balanced Mains out when I moved the HiFi from the lounge and didn't miss it. Well, the room was so different and needed a lot of acoustical treatment, so that that was the focus. And in the lounge I always had something sitting on top of or against the Balanced Mains chassis, which my experiments are now showing that chassis damping has a big effect on how the high frequencies are treated. So I was pretty surprised when I plumbed it back in a few weeks ago and started listening -- well on the second day. The first hours were a slight improvement but not too remarkable. The next day it was like some fairy had exchanged my components for something much better than I could ever afford. Lot's of grinning for a week or two until I decided to "improve" things. That noname soft start module from Ebay certainly throttled things but I'm finding my way back. |
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