John Curl's Blowtorch preamplifier part III

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Well the odd thing here is that high end audio, egged on by many, became a lifestyle thing this century so was as much about 'look at my wad' as it was quality. Few companies have refused to go that path. Benchmark is one, possibly because they sell as much to the pro market as domestic?


I think it should be possible to put together something very high performance for not silly money. well beats wearing yoof would think it silly...


But what is the criteria for high performance?
 
BTW the 99 dollar HPA was measured at 300 Ohms. NFG.

????? Probably that damn feedback.

Switching to 33 ohm load we get:
Similar picture emerges. We have slightly less power output but much, much lower distortion and noise. You get one full watt of power at just 0.0009% distortion. Incredible.

BTW What's up with the Sennheiser hate? A grateful customer gave me a pair of HD-650's in return for help on a HDA design using a re-purposed ADSL driver that are getting a little crufty and I was thinking of upgrading to the HD-800's. When it comes to transducers it's pure opinion.
 
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Wales, similar thing in some places. :p


Edit: for anyone who remembers 'the prisoner'. He's just down the road from there. Lucky *********.

Before the Cob was built at Port, Penrhyn was a very remote peninsular with very little reason to come here, still is like that out of the holiday season, nice. There used to be a ferry from Talsarnau to Minffordd near Portmeirion and one from Garreg to Prenteg on the other side. In Port there is an area called Penamser (end of time) where the Penamser Bell was rung to warn of the tide changing and last chance to cross.
St Brothen's Church at Llanfrothen has a sloping aisle and it is rumoured that before the Cob was built spring tides would creep up it...
 
BTW What's up with the Sennheiser hate? A grateful customer gave me a pair of HD-650's in return for help on a HDA design using a re-purposed ADSL driver that are getting a little crufty and I was thinking of upgrading to the HD-800's. When it comes to transducers it's pure opinion.

Nothing is wrong with them. They are not my kind of professional headphones as most pro uses in my end of stuff is to check on how things sound in solo mode. So open air designs are not very useful.
 
I was referring to the -116dB on that graph, there was no footnote to a study that established that.

As you surely know that scottjoplin´s assertion is nonsense i´m a bit surprised that you just quoted it as if it could be true.....

@ gpauk,

Surely, that should be:
"I see not protocols or detailed repeatable process laid out to verify any claim of audibility"

That is just scottwurcer´s original sentence, which i used for the sake of the argument.
The reason for demanding more controlled listening routines is the problem of internal validity. Any knowledge about what you´re listening to is known to be a potentially confounder leading to incorrect results wrt the original research question.

In this context it doesn´t make a difference if a listener expects to percept a difference or expects to _not_ detect a difference, the problem is just the same.

Therefore complaining about the lack of rigor or protocol description for an assertion about audibility while pointing to a result from personal listening obviously also without mentioning of any protocol/methodology, seems to be strange.
But it can be found quite frequently in threads where audibility (and or statements/claims about audibility) is part of the topic.
 
BTW What's up with the Sennheiser hate? A grateful customer gave me a pair of HD-650's in return for help on a HDA design using a re-purposed ADSL driver that are getting a little crufty and I was thinking of upgrading to the HD-800's. When it comes to transducers it's pure opinion.

The HD800 is good, but needs EQ I think. They are ok without it, but the upper mids can be aggressive and any sibilance seems emphasized. Almost the polar opposite of the 650 in some ways. I got used to it, but switching between the two is a bit rough until your brain adapts.

I’m very curious to try the closed HD820 with gorilla glass back. I don’t like most closed headphones, but some isolation is welcome. Apparently they are controversial and the price is not so great, though.
 
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Nothing is wrong with them. They are not my kind of professional headphones as most pro uses in my end of stuff is to check on how things sound in solo mode. So open air designs are not very useful.

My new house is very quiet at night, I already mentioned that my TT motor is now annoying. How would your threshold numbers work out using headphones? I managed to get Python to generate and play random .wav's so I was thinking of some solo blind tests on thresholds, basic stuff at first, audible noise floor, tones below noise floor, etc. I already know I can't detect broadband noise at dithered 16 bit level, off or on I hear nothing. I would like to keep it at quality of equipment does not matter level for now.
 
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I have the same problem on one of my TTs, but it's belt vibration. Lift the lid and it goes away, but when I am the only one up I can just hear it from the listening position if no music playing. I have recommissioned the koss ESPs but need to make a longer cable so I can sit down to listen.



Headphones are vital if I want to listen to 'music for organ and weather satellite' :)
 
Ah the confusion and lack of common ground.

What is distortion? What is THD or IMD? If you have THD in an amplifier must you also have IMD? Does the same hold true for a loudspeaker driver?

What is the effect of masking? Hint low frequencies can mask higher frequencies.

What is the musical perception of THD, IMD?

What are the perceptable limits of dispersion? (What does dispersion mean in acoustics?) How does that relate to phase shift versus frequency?

Just a few of the basic issues that are well researched and applicable to much bouncing around here.

It would be difficult not to. I doubt you could come up with any weakly non-linear system that does not behave as expected.

Seems that Scott came close on one of the issues, but it is the sum that is required to cover the topic.

But can anyone tell me what would the acoustic output be from a 4" diameter massless piston in a perfect surround driven by a massless voice coil in a perfect magnetic field powered by a flat voltage 0 impedance voltage source from a frequency range of 100 to 800 hertz?

How does that influence the IMD of a perfect piston?
 
My last recommendation should be to keep an open minded attitude. If somebody claim something that seems both 'reasonable' and interesting: I try by myself. I have learned a lot of things this way. And if it is not working with my personal configuration, I do not take definitive conclusions, we don't tune carburetors and injectors the same way.
You would never have closed mind when reading about the use of Shakti Stone for audio improvement?

Of course, measurements are the only irrefutable way to figure out if any difference or improvements. But I keep for granted that measurements results do not tell so much about our listening experiences.
Brainwave measurement can tell much about our listening experiences.

Bad measurement results will sound bad, good ones does not necessary imply a system will sound so good.
Good measurement meaning hi-fi?
 
Well the odd thing here is that high end audio, egged on by many, became a lifestyle thing this century so was as much about 'look at my wad' as it was quality. Few companies have refused to go that path. Benchmark is one, possibly because they sell as much to the pro market as domestic?

High quality audio reproduction was always luxury.And within this luxury department there is and was demand for something more special and expensive.
Concentration on just a subset of functions while trying to deliver these in the best possible way was imo the main driving force at least at the beginning; that you can´t negate the usual laws of markets should be a given.

At the core it is just trying to get the best perfomance at a given (price) point, so to speak "high end" is separated from high prices. See for example the old "pooge - articles" in the audio amateur or the efforts within diyaudio forums.

I think it should be possible to put together something very high performance for not silly money. well beats wearing yoof would think it silly...

It always was and using todays worldwide access it is even easier than before, if we neglect the negative connotation for the moment.

But what is the criteria for high performance?

That was always mainly a matter of personal demands, but if you want something that resembles reality, is able to replay any style of music without loosing that ability at any level required in a quite large space, it still is something that will cost a lot of money, even more if the owner likes the "Burj al arab" style approach.....
 
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I think it should be possible to put together something very high performance for not silly money. well beats wearing yoof would think it silly...

So assuming the source is a streaming device that exists, a system comprises DAC, PA, LS.... What's your view on what you need to spend for not silly money devices to get high performance in each category... Imaginary shopping time!
 
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