SY said:
I ordered some from a guy and he balked at taking the order when I told him I would be able to tell if they were fake.
john curl said:
Just curious, what makes you an expert in noise and in particular JFET noise? I know a former visiting professor in electron device physics and modelling at Stanford and TAMU universities, occasionally reading and posting on this forum that, based on your contributions here, would not give you a pass mark.
OK. I just work to 0.4nV rt/Hz and have done so since 1973. That is the total equivalent noise of a 10 ohm resistor. No transformers allowed. Try it sometime.
scott wurcer said:
Oh, THAT is comforting.🙄
Anything a reasonably well-equipped amateur could probe for? gm? Noise?
John,
Not trying to be offensive here, in any way…
I’m a bit confused about your statements regarding the objectives you try to point this thread at.
Are we all going to benefit from this? In what way?
Are you trying to design, with the help and input of some others very good audio people that contribute to these forums, “a beyond the BT” preamp? To the benefit of the community? And have the schematic posted in the way many others have done?
Or is it for your own benefit only?
🙂
Not trying to be offensive here, in any way…
I’m a bit confused about your statements regarding the objectives you try to point this thread at.
Are we all going to benefit from this? In what way?
Are you trying to design, with the help and input of some others very good audio people that contribute to these forums, “a beyond the BT” preamp? To the benefit of the community? And have the schematic posted in the way many others have done?
Or is it for your own benefit only?
🙂
scott wurcer said:
Bdent.com, the real thing. Just got new stock in. Received my backorder Friday. K170BL, J74BL.
scott wurcer said:
I ordered some a couple of months ago. Scott if you want a couple I will send them to you.
hitsware said:
You must be totally delusional.
The graph as you call it is clearly showing an amplifier that is adding a lot of high level artifacts that weren't there in the original signal. This is not the hall mark of a good amplifier. It is more the characteristics of a sound effects generator.If you prefer the sound of this over an amplifier that is transparent and uncolored then that is your prerogative. Just don't tell me that the differences in sound coming from this amplifier can only be explained with reference to paranormal science
This amplifier example is a sick version of what is normally available from tube designs. Tubes almost always have some measured distortion, but even a Dyna that originally cost $100 new. will measure better than this example. Please, study first, before criticizing any audio component.
>The graph as you call it is clearly showing
>an amplifier that is adding a lot of high
>level artifacts that weren't there in the
>original signal. This is not the hall mark
>of a good amplifier.
You are missing my point. I am saying
that perhaps the 'magic' happens in
spite of the distortion, rather than
because of it. There are obviously other
things going on in amplifiers than how
they graph, or else amps that graph
the same would sound the same, which
is clearly not the case.
An engineer I worked for once said that any
distortion spec below 0.5 % was superflorus
in that other factors in the design would
affect the sound to a greater degree.
>an amplifier that is adding a lot of high
>level artifacts that weren't there in the
>original signal. This is not the hall mark
>of a good amplifier.
You are missing my point. I am saying
that perhaps the 'magic' happens in
spite of the distortion, rather than
because of it. There are obviously other
things going on in amplifiers than how
they graph, or else amps that graph
the same would sound the same, which
is clearly not the case.
An engineer I worked for once said that any
distortion spec below 0.5 % was superflorus
in that other factors in the design would
affect the sound to a greater degree.
>Now, my latest criticism was about
>the nature and noise properties
>of fets, which I am an expert in the field.
Dear expert,
Some bipolar MC preamps use multiple xsistors in
parallel in the first stage to lower noise.
Can jfets be paralleled for the same advantage ?
Mosfets ?
>the nature and noise properties
>of fets, which I am an expert in the field.
Dear expert,
Some bipolar MC preamps use multiple xsistors in
parallel in the first stage to lower noise.
Can jfets be paralleled for the same advantage ?
Mosfets ?
Hitsware, you are absolutely right, but it is pointless to argue it here.
Also, we parallel either bipolar, complementary bipolar (I have a patent on one version of this) or jfets, either single sided or complementary.
I use 4 complementary jfets for the Vendetta Research input stage running at 30ma to achieve 0.4nV/rt.Hz noise from 400 Hz on up. Slightly worse, but acceptable full range, IF I keep the air currents around the devices still. This takes a sealed box. I have been doing this for about 25 years, and am still at it. Unfortunately the Toshiba parts that make this happen have not been made for about 15 years, or more, and therefore obscenely expensive, but they ARE quiet.
Also, we parallel either bipolar, complementary bipolar (I have a patent on one version of this) or jfets, either single sided or complementary.
I use 4 complementary jfets for the Vendetta Research input stage running at 30ma to achieve 0.4nV/rt.Hz noise from 400 Hz on up. Slightly worse, but acceptable full range, IF I keep the air currents around the devices still. This takes a sealed box. I have been doing this for about 25 years, and am still at it. Unfortunately the Toshiba parts that make this happen have not been made for about 15 years, or more, and therefore obscenely expensive, but they ARE quiet.
My point (surmised only) about power mosfets being quiet
is that power mosfets are comprised of many 'cells'
in parallel.
Isn't a 'cell' actually analagous to an individual mosfet?
Therefore wouldn't many cells in parallel exhibit this
quieting effect? Even if the cells are noisy individually,
it seems that with so many, quietude would manifest.
is that power mosfets are comprised of many 'cells'
in parallel.
Isn't a 'cell' actually analagous to an individual mosfet?
Therefore wouldn't many cells in parallel exhibit this
quieting effect? Even if the cells are noisy individually,
it seems that with so many, quietude would manifest.
Mosfets are VERY NOISY!!!!!!!! BIGTIME NOISE Gm is not the problem. It is 1/f noise. 1000 times more noise at 10 Hz than good jfet.
Read Willy Sansen: 'Noise Sources in MOSFET Transistors' Google it, please!
Read Willy Sansen: 'Noise Sources in MOSFET Transistors' Google it, please!
apassgear said:
Though we had had some misunderstanding in the past, I have learned a lot from John on design philosophy of input stages.
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