PRaT - please explain

[Lawrence001]

Did I read a while ago that Naim took an earlier (US?) amp design that had fallen out of favour, and basically reinforced the attack at the expense of the decay of a wave in order to make the music more exciting? I didn't know about the peak at 80hz but that would help in a demo I suspect.

Presumably Naim fans will tend to listen to the sort of music that would benefit from this effect, rock, pop etc over unamplified instruments, although I can see acoustic guitar and maybe brass sounding more exciting as well. Nor sure about strings and woodwind sections though, so orchestral/chamber music may fare less well.

[anthonyTD]

I think the term is more akin to describing the person, more than anything associated with musical interpretation!

[Light Dependant Resistor]

PRaT was a bit of hype from the glory days of the Linn/Naim Flat Earthers. Pace, rhythm and timing are (amongst others) worthwhile and desirable attributes in a system. But of course, any decent Hi-Fi will have them. There's no mystique about this.

Sadly no, the majority of audio systems fail to address what is possible with timing in a audio system.

If we consider some circuitry and look at the way DC is used in audio systems, what we see is very lazy, abysmally lowest cost, implementation.

My specialist area, is the relationship - (which sounds extremely boring ) of the anodes of a shunt pair , cathodes of a shunt pair, the anodes of a series pair, and the cathodes of a series pair
of LDR's I have been investigating and improving this circuitry for over 11 years, and without reservation there is more in audio improvement to be found here, then any other part of a audio system.

This assumes the other parts of a audio system are very good, but not overtly so, My system is modest compared to some, it comprises good sources of Pioneer stable platter CD player, a suite of 5 Yamaha
CDR HD1500 recorders/ players, a stereo coffee attenuator, two quad 306 power amps, and various loudspeakers comprising ESL57, JR149 ( which i use the most ) and Gale GS401a. I use one pair of speakers
at any given time.

The work I have done finds what is missing in other audio systems principally aligning timing from the source component to the power amp, using akin to current drive -the load of the cathode to readdress the anode.
a thread where the circuit is discussed is here. https://www.stereo.net.au/forums/top...eamp-redesign/

[anthonyTD]

Chris, with all due respect, what your describing here will just go over most folks head, why not just show how linear your system is with say; a 50k to 200k Square wave from a 50 ohm source, comparison in and out of your Stereo Coffee LDR preamp, at diffrent volume settings, that may give a better understanding of what your trying to say about your design as far linearity, and its ability to reproduce signals as close to the original, in real time.

Sadly no, the majority of audio systems fail to address what is possible with timing in a audio system.

If we consider some circuitry and look at the way DC is used in audio systems, what we see is very lazy, abysmally lowest cost, implementation.

My specialist area, is the relationship - (which sounds extremely boring ) of the anodes of a shunt pair , cathodes of a shunt pair, the anodes of a series pair, and the cathodes of a series pair
of LDR's I have been investigating and improving this circuitry for over 11 years, and without reservation there is more in audio improvement to be found here, then any other part of a audio system.

This assumes the other parts of a audio system are very good, but not overtly so, My system is modest compared to some, it comprises good sources of Pioneer stable platter CD player, a suite of 5 Yamaha
CDR HD1500 recorders/ players, a stereo coffee attenuator, two quad 306 power amps, and various loudspeakers comprising ESL57, JR149 ( which i use the most ) and Gale GS401a. I use one pair of speakers
at any given time.

The work I have done finds what is missing in other audio systems principally aligning timing from the source component to the power amp, using akin to current drive -the load of the cathode to readdress the anode.
a thread where the circuit is discussed is here. https://www.stereo.net.au/forums/top...eamp-redesign/

[Macca]

a thread where the circuit is discussed is here. https://www.stereo.net.au/forums/top...eamp-redesign/

There's no discussion of the circuit on that thread, are you sure it is the right one?

[Pharos]

I don't doubt that there are timing errors in Hi-Fi, but their significance, or even detectability needs verifying, and the PRaT people I have talked to over the years do not indicate seriously better perceptive ability sensitivity or subtlety in their personalities, often quite the reverse IME.

I would Chris, like the science at least outlined, and preferably explained, or the desired changes and the objectives it achieves described.

[Light Dependant Resistor]

I don't doubt that there are timing errors in Hi-Fi, but their significance, or even detectability needs verifying, and the PRaT people I have talked to over the years do not indicate seriously better perceptive ability sensitivity or subtlety in their personalities, often quite the reverse IME.

I would Chris, like the science at least outlined, and preferably explained, or the desired changes and the objectives it achieves described.

Hi Dennis
The best way of demonstrating this, is for you to start just like I did 11 years ago, and see this for yourself. It will become apparent that LDR's are somewhat better than
other passives straight away, but can be far better still, reproducing music if we spend some time investigating, and NEVER giving up on saying - it cannot get any better,
because it can. I think though what I have done is at the mountain top so to speak, of LDR's being used in audio circuits.

You will need

10 x NSL32SR3 , of those you should be able to get a L pad comprising 3 inputs, the other two might be able to be used at a later date. The NSL32SR3 is not totally consistent with manufacture, so some just will not match.
4 x 2k ten turn trimpots
A circuit board for mounting the LDR's. I can send you a LDR board which will make mounting them very easy
a 50k Bourns Single gang Linear potentiometer

Now the next part is where we begin to see there are differences with how the LDR is powered. So I am not just writing ad infinitum ,
how do you think the LDR should be powered ? .... it gets as interesting as you can possibly imagine ..

The requirements you need to meet are current cannot exceed 20ma per device, you need to head for no more than 4.5ma per LDR
The LDR is quite capable of being a switch and a variable resistor, so we will plan to make the series pairs switches when OFF as well as
variable resistors when ON

We need to have some method of altering that resistance, so we do this via the LDR cathodes, placing the 50k Vol up to the Series cathodes
and Vol Down to the shunt pair cathodes, and we will use a lower potential for the Wiper, but NOT ground.

We will continue once you have some parts ready, and are in dialogue about possible methods to power.

[Pharos]

At my position in life, after many years of building equipment in a period in which major gains in performance against cost were possible, I do not work on anything other than speaker design.

My contention is that largely, electronics has conquered its aims, and is very near perfect, but that speakers are still very much more flawed.

I do not know what an LDR is BTW, but I would need well documented evidence, from reliable and respected sources stating that preamps can be improved on to a significant extent before considering the new implementations.

If passives were a 'new breakthrough', surely some of the well known and scientifically established 'gurus' would be touting their benefits.

[Light Dependant Resistor]

At my position in life, after many years of building equipment in a period in which major gains in performance against cost were possible, I do not work on anything other than speaker design.

My contention is that largely, electronics has conquered its aims, and is very near perfect, but that speakers are still very much more flawed.

I do not know what an LDR is BTW, but I would need well documented evidence, from reliable and respected sources stating that preamps can be improved on to a significant extent before considering the new implementations.

If passives were a 'new breakthrough', surely some of the well known and scientifically established 'gurus' would be touting their benefits.

Actually what you have to contend with, rather than reaching nirvana instantly with LDR's is manufacturing enjoying making money and offering parts that are the worst of the worst
as people just continue paying. There is objection at many levels ( - yes hifi has politics ) when someone creates something better.

The history of the rheostat designed in the 1800's but patented by Mary Hallock Greenewalt in 1919 is testament to what then became the potentiometer, being originally designed
for entirely different purpose, namely a visual music she called Nourathar. Early forms of the potentiometer were stepped attenuators, and most manufacturers closed their eyes
when the asian equivalent the carbon track pot was released, and those in the know haven't opened them yet.

I can point you to review of LDR's as passive attenuators https://www.stereo.net.au/forums/top...eamp-redesign/
You can also follow some technical information here: https://lunainc.com/product/optocouplers/


Actually the other way around, we tend not to notice loudspeaker imperfections if speakers are good already, but electronics imperfections ( Yes the T word ) are obvious.
The link here is David Blackmer discussing how we tend to mask loudspeaker errors and the importance of time. On one hand he says
Loudspeakers turn time into a pretzel, alluding that planar speakers are relatively free of these errors, but is referring to other errors prior to loudspeakers.
https://www.youtube.com/watch?v=j71NrNMx2rU

[Blueflash]

If you play a CD like Elton John "Don't Shoot Me I`m Only The Piano Player" on some of the tracks the drum kit has been recorded with a tiny amount of echo.
It was not until I built the DDDAC that I noticed it. Some systems can miss either the leading or following echo if they do not have the resolution to show it up. My earlier system was missing some of the edges and it did give the impression of something out of sync, only slightly, but it was there.
So I thing the lack of PRAT is a resolution problem somewhere along the reproduction chain. In my case it was the DAC, with someone else it could be the pre or power amp, or the speakers and room interaction.
It is worth pursuing because it will also flatten or artificially bloat the sound stage and depth.