Yes, he's holding off on the Nobel prize for room temperature super-conductivity because he doesn't need the money.
What about the listening experience with Markw4's products? Or was there any?
I need time to catch up with these things
For new how about this Analog Corner #297: van den Hul The Grail SE+ phono preamplifier & SAEC WE-4700 tonearm | Stereophile.com
How you can add $21k onto the same basic circuit is a miracle of marketing. I also smile at the error in the description marked in bold.
Current injection is the correct term.
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I did the transimpedance input (resistor between output and input) in the Levinson JC-1 pre-preamp in 1973. In 1975 I tried an 'improved' transimpedance input (complementary emitter input) and found that it sounded (underwater) compared to a 100ohm load. I now prefer a variable loading from 10ohm to 50K, wherever it sounds the most natural. Every MC phono cartridge has a 'sweet-spot', usually between 100 and 300 ohms. Some exceptions prefer more or less loading. I suspect VDH optimizes his cartridges for low Z loading. He said so, himself when he gave a talk in the SF bay area around 1980. However, for awhile, Harry Pearson of TAS preferred 47Kohm, in order to remove the need for a preamp or a transformer ahead of a low noise MM phono stage.
In conclusion, low Z input sometimes works well, sometimes it doesn't, depending on the MC cartridge model and adjustment.
In conclusion, low Z input sometimes works well, sometimes it doesn't, depending on the MC cartridge model and adjustment.
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I found low impedance as in zero (not really attainable) to just a few ohms works just fine.
The low output MC carts often have very high current outputs which you can exploit for better noise than would be possible if you just dealt with it in the normal voltage mode. Kudos to Marshal Leach for recognizing this back in 1978!
I have two MC pre’s in my set-up. One is a BF862 input stage with helper transistor (See H&H AoE X Files) which is remarkably quiet and works great with the Hanna SL (which I no longer have - it was a loaner for a show I did) and the other is a current injection stage that I am presently running a DL103 through.
How do you get rid of a MC pre with 47k loading? Some of these things only output 100 or 200 uV at 1kHz whereas a typical MC input sensitivity is 3-5 mV.
The low output MC carts often have very high current outputs which you can exploit for better noise than would be possible if you just dealt with it in the normal voltage mode. Kudos to Marshal Leach for recognizing this back in 1978!
I have two MC pre’s in my set-up. One is a BF862 input stage with helper transistor (See H&H AoE X Files) which is remarkably quiet and works great with the Hanna SL (which I no longer have - it was a loaner for a show I did) and the other is a current injection stage that I am presently running a DL103 through.
How do you get rid of a MC pre with 47k loading? Some of these things only output 100 or 200 uV at 1kHz whereas a typical MC input sensitivity is 3-5 mV.
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There are a number of things that I don't agree
1)" A transimpedance topology has always a few ohms input impedance. "
This is true for a Leach sort of design, showing 2 to 3 Ohms Input Impedance.
However my design over here, has a below 0.01R input impedance
Designing a universal diff-in/diff-out Head Amp
I used the text "Virtual Input Module" above the image, this was short for "Virtual Ground Input Module".
2) comparing a transimpedance with a different voltage amplifier is comparing apples to pears.
A conclusion that transimpedance sounds "muddy and underwater" can never be substantiated in that case.
Only when comparing both with exactly the same amplifier module can lead to valid conclusions.
This is what I did in the above link.
Apart from this, it can very well be that not all Carts like to being played over a transimpedance, my experience restricts to just one Cart.
Hans
1)" A transimpedance topology has always a few ohms input impedance. "
This is true for a Leach sort of design, showing 2 to 3 Ohms Input Impedance.
However my design over here, has a below 0.01R input impedance
Designing a universal diff-in/diff-out Head Amp
I used the text "Virtual Input Module" above the image, this was short for "Virtual Ground Input Module".
2) comparing a transimpedance with a different voltage amplifier is comparing apples to pears.
A conclusion that transimpedance sounds "muddy and underwater" can never be substantiated in that case.
Only when comparing both with exactly the same amplifier module can lead to valid conclusions.
This is what I did in the above link.
Apart from this, it can very well be that not all Carts like to being played over a transimpedance, my experience restricts to just one Cart.
Hans
I didn’t get to try the Hanna on the current injection IP stage. But given it’s very high generator R (130 Ohms IIRC), this makes the input current very low. It may well be that this type of cart is best suited to Voltage input type stages - the output is c. 500 uV.
An excellent sounding cart BTW
An excellent sounding cart BTW
Andrew,
What potential problem do you see when connecting a 130R 0.5mV@1Khz Cart to a transimpedance amp ?
Hans
PS I just noticed that the Hana SL with 0.5mV output has a 30R generator impedance
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