HPS 4.0 phono stage

[Joachim Gerhard]

P.S: The input THAT chip is of cause bipolar but the rest is j-fet.

[Lumba Ogir]

Michael,
so glad to see your strong desire to acquire entertaining documents, constituting an enlightening source of information, digging up the deep essence of things, very amazingly, the shots always landing exactly where the truth lies.

[syn08]

Originally Posted by Spambot

so glad to see your strong desire to acquire entertaining documents, constituting an enlightening source of information, digging up the deep essence of things, very amazingly, the shots always landing exactly where the truth lies.

And doesn't this remind you of when you were in the boat, and then later than night, you were lying, looking up at the ceiling, and the water in your head was not dissimilar from the landscape, and you think to yourself, "Why is it that the landscape is moving, but the boat is still?"

[MRupp]

Concerning negative impedance there needs to be a sensor inserted from cardridge to input.

You may be aware that Ed Meitner has a patent on a "Magnetic pickup preamplifier", US4547819 where "a magnetic pickup ... is terminated by a negative impedance ..." but this is for MMs and he "appears" to be manually calculating the necessary feedback compensation from the stray capacitance and resistance values of the cartridge and is not sensing it thru a resistor (here, Nelson Pass' aleph current source comes to mind).

A design can attract my attention only if the designer has ... some reasonable base reference - either some recognised commercial or diy design ... but emitter followers at the input hardly qualify as ultra-cool.

The new Accuphase C27 phono preamplifier applies followers (JFETs in this case) at the input of the MM circuit (basically the same topology as the MC circuit but built separately on the same board) and obviously to allow for a higher input impedance. I cannot comment on what syn08 had in mind but that could be a possibility. Not sure though if you would consider the Accuphase a cool preamp, probably not

[analog_sa]

Originally Posted by MRupp

Not sure though if you would consider the Accuphase a cool preamp

Certainly would. Thanks for pointing this out.

[Lumba Ogir]

analog_sa,

Not sure exactly why exactly the "hopeless" Lumba, whose posts i greatly enjoy, won't build it, but here are my reasons.

I won't build it. As stated, the grounded base input topology is not negotiable and because of other disorders.

but emitter followers at the input hardly qualify as ultra-cool

To put it mildly, since the opposite characteristic is desirable.

The new Accuphase C27 phono preamplifier applies followers (JFETs in this case) at the input of the MM circuit (basically the same topology as the MC circuit but built separately on the same board) and obviously to allow for a higher input impedance.

Life never ceases to surprise. A convincing reasoning is likely to be found in the glossy brochure included.

I cannot comment on what syn08 had in mind but that could be a possibility.

It could. At the same time, people confusedly talk about impedance matching, cartridge loading and negative input resistance.

[Lumba Ogir]

Joachim,
I`m more interested in hearing something about J. Hiraga, one of the very few designers of dignity, with a rare genuine sense for audio. Being a tube guy, he also understood the essential nature of transistors more than most other "engineers".

[Joachim Gerhard]

He was exhibiting at the High End show in Munich. He has a new loudspeaker with Altec wide band, you know with the Manta Ray horn.
The funny thing was (actually not funny at all) that a tube amp he had on idle during the night put a wooden board on fire that was thermally too close to the tube amp. The sprinkler got on and the water and dirt was dripping down in the first floor flooding an open stand of a company from Italy, i do not remember the name. A total mess and as far i heard there was no enshurance paying the considerable amount of damage done.

[syn08]

Originally Posted by Lumba Ogir

As stated, the grounded base input topology is not negotiable and because of other disorders.

To put it mildly, since the opposite characteristic is desirable.

At the same time, people confusedly talk about impedance matching, cartridge loading and negative input resistance.

Out the window play the unicorns of ham, soothsayers on the wall catch light in silver jars, never trust a swamp dweller they tend to break unexpectedly.

[Bonsai]

When designung low noise circuits, the theory generally is that you have try to have the highest gain in the first stage (of course, taking good care not to cause overload etc) in order to minimize the noise contribution. So, my question about these common base 0db voltage gain designs at the INPUT of a high gain amplification chain is: do they not add more noise than they should? Why buffer the mc cartridge when it is quite capable of driving happily into 100 Ohm load impedance? I, correctly or not, would have tried to put as much gain into the head amp as possible and avoided the buffer. What am I missing? Help me out here!