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1970s Design Indulgence

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Graham Slee View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jun 2019 at 11:23am
Having tried the flux-band on two different laminated transformers I can say I have not detected any difference in off-load current.

I also tried one from the amplifier, with and without its mounting frame, and was unable to measure any difference in off-load current.

I will qualify the above: there were changes during measurement which were in my opinion due to mains voltage drift, which you will get at certain times of day, especially on Sundays when some still cook the traditional Sunday lunch!

At this point two articles fork, as I am about to fit the other flux-banded transformer to the 5V 3A power supply.

Whether or not the flux-band works will have to wait for the laminated transformers to go back into the amplifier. Why I'm fitting a flux-banded transformer to the power supply is a matter of "faith".
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Graham Slee View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2019 at 8:52am
Transformer research is hopefully drawing to a close.

Although the Antek 3450 toroidal returned a good performance, it didn't last the full week. It couldn't prevent the present day high frequency mains pollution 'fizzing' the electrolytics, which meant eventual bass loss.

(See chart here: https://www.audialonline.com/blog/psu-transformers-ei-vs-toroidal-and-more/ more info here: https://www.soundstagenetwork.com/maxdb/maxdb071998.htm)

The RS EI transformers are back in for the time-being, but will eventually be replaced by a pair of custom-made EI transformers from Transtronic.

These will have lower saturation at approx. 1.1T. The RS ones are approx. 1.4T. And mechanical noise should be lower.

Using more laminations, the Transtronic ones should allow a larger shadow region against magnetic fields, and this might improve the mains hum.

Currently, in a silent room, the hum can be just heard 300 mm away from the bass drivers of the LS3/5A's, but any further away it isn't heard.

I am sure the eventual declaration of S/N specification will be a turn-off for some, but what would they rather have? I would rather have full-bodied music than ice-cold thinness.

If it makes this amplifier mid-end or low-end in people's estimation, then let it be. All I know is that different artists or bands use different recording techniques, and some throw a lot of brightness into it. If then the amplifier cannot do justice to what's left of the bottom end, you simply discard the music and listen to something else. This results in picking the music to suit the equipment, and if that is what the high-end is about, then it isn't about music!

I think I have said the above so many times that people are fed up to the back teeth of reading it, but that is my way, and has been all-along.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2019 at 12:10pm
I am surprised you would use a speaker for the reproduction of analyzing your amp qualities like the Ls4/5A when I am sure that "they" wouldn't be the ones also in your Main set-up for enjoyment listening...? Do you actually rely on something quite removed from a studio monitor?  Before I get myself into more trouble...Graham - what is it with capacitors that, when you use them for biasing, a larger voltage [ac or dc, i'm not sure which you do it for] will give a better result? 
It is also true when using capacitors in a loudspeaker crossover network that 'using a high' [400V or 600V] against a lower 100V or so, is the more preferred way to get a better result?? And while we're at it, using multiples to get the final capacitance, eg. paralleling a 100 + 50 + 25 + 0.01 biasing cap to get 175uF ? 
Good to hear finally the amp is sounding pleasing to it's master! Clap 

DogBox
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Edited by DogBox - 22 Jun 2019 at 12:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2019 at 2:35pm
Originally posted by DogBox DogBox wrote:

I am surprised you would use a speaker for the reproduction of analyzing your amp qualities like the Ls4/5A when I am sure that "they" wouldn't be the ones also in your Main set-up for enjoyment listening...? Do you actually rely on something quite removed from a studio monitor?

The PMC LS3/5A speakers that Graham uses are studio monitors. These speakers have been given a special endorsement by the British government for accurate audio reproduction. They are also used in BBC broadcast vans and studios. 
 Since Graham has considerable experience with these speakers, he chose them for his critical listening tests.

 You can read elsewhere here that Graham has done extensive listening room treatments. He is very particular about the quality of sound he listens to.

 I could not resist Graham.
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ICL1P Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2019 at 3:04pm
Are they PMC?
Ifor
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Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris Firth Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2019 at 3:25pm
Originally posted by ICL1P ICL1P wrote:

Are they PMC?


If memory serves they're from Stirling Broadcast, or at least the ones I saw at the Carnage Show a few years ago were.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2019 at 4:20pm
Originally posted by ICL1P ICL1P wrote:

Are they PMC?
 I thought they are. I am not familiar with them any more than what I read on the forum.

Point is Graham likes them enough to use for critical listening.
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!
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