I think I have found the reason by reading about the topic "load impedance of cartridge" that MC have very low output impedance so x10 load could be around 100 ohm. I am not vinyl-guy.....so new for me....I am an novice especially regarding phono-amps.......therefor I have a stupid question:
There is a dip-switch at the front-end which can switch-in various resistors / capacitors to load the cartridge.
Regarding the resistors there is as low a value as 50R. When do you need to use such a small value? .....it will almost "kill" the signal from the cartridge?
Or do I read the schematic wrong regarding the dip-switch circuit (it looks like it switch in resistors from input to gnd parallel with the 47k input resistor)?
Is it for very high output cartridges where you need to lower the input signal by loading the cartridge?
I am using DAC only.......and I am used to do everything to preserve as much as the signal as possible
I wonder how many that would like to try out a Burson discrete opamp for this circuit.....
I'm not a vinyl guy either but from what I've read, the recommended loading for MC cartridges can be quite varied. (For example, I've seen some at 1K and others at 30 ohms)
It's very handy having loading adjustments on the PCBs.
Cheers,
Dennis
Check the manufacturer's datasheet for the Accuphase AC-3 cartridge. Tells you "here is the cliff of death; stay away from the cliff of death" but you (not the manufacturer) must decide how far away gives the greatest enjoyment.
@MEPER Moving magnet cartridges tend to work with a 47k ohm input impedance. Moving coils are a lot more variable, but one rule of thumb is to set the impedance at least 10x the specified impedance of the cartridge. It's pretty common for inexpensive off-the-shelf phono preamps to have a MC setting somewhere around 100 ohms as a generic answer. It is also pretty common for moving coil aficionados - of which I am one - to obsessively fiddle with various cartridges and turntables and tonearms and preamps and adjustments to tracking force and anti-skate and preamp settings (I haven't mentioned capacitance yet) and other details. Sort of like how some folks on the Pass DIY forum happily and endlessly discuss output transistors...
A topic for a different forum, I'm sure.
(The physical setup is much more important than electronic loading re. record wear.)
A topic for a different forum, I'm sure.
(The physical setup is much more important than electronic loading re. record wear.)
Cartridge loading has nothing to do with record wear. It's more about having a resistance across the coil of proper value to keep frequency response flat.
The Accuphase cartridge says recommended loading is more than 30ohms. 50 will likely be perfect.
"50 will likely be perfect" . . . . . hmmm . . . . . .
I recommend calculating f = cube_root(50 / 30) and, when you do, I predict you'll get f = 1.1856.
Then I recommend trying every resistance in the (geometric) sequence: 30 , (30*f) , (30*f*f) , (30*f*f*f) , (30*f*f*f*f), etc as your cartridge termination resistor.
Experimentally discover which one sounds best with your cartridge and your turntable and your preamp and your amplifier and your speakers. Maybe 50 will be the winner, maybe not. Run the experiment, gather the data, arrive at a conclusion.
I predict your sequence of resistance values will resemble: 30.00 , 35.57 , 42.17 , 50.00 , 59.28 , 70.28 , 83.33 , ... etc. Feel free to round to the nearest EIA96 value that your resistor vendor has in stock.
I recommend calculating f = cube_root(50 / 30) and, when you do, I predict you'll get f = 1.1856.
Then I recommend trying every resistance in the (geometric) sequence: 30 , (30*f) , (30*f*f) , (30*f*f*f) , (30*f*f*f*f), etc as your cartridge termination resistor.
Experimentally discover which one sounds best with your cartridge and your turntable and your preamp and your amplifier and your speakers. Maybe 50 will be the winner, maybe not. Run the experiment, gather the data, arrive at a conclusion.
I predict your sequence of resistance values will resemble: 30.00 , 35.57 , 42.17 , 50.00 , 59.28 , 70.28 , 83.33 , ... etc. Feel free to round to the nearest EIA96 value that your resistor vendor has in stock.
Knit Two Pearl 3
Hello All,
I am picking parts for this project. Resistors first.
I am going with the larger body Vishay RN60's 1% and 50 ppm or better. There is less selection, higher price for improved % and improved ppm. If there is the option I will go for the larger RN60, + lower % and lower ppm part.
The lower % part is intuitive.
The larger body has a larger thermal mass resistive element. There is reduced temperature swing (delta t) => less thermal caused resistor distortion.
The larger body has a larger thermal mass body, cools faster, does not get as hot, produces less thermal noise.
Lower ppm works with the larger thermal mass resistive element to further reduce thermal caused resistor distortion.
Thanks DT
from APx555 testing on my bench
Hello All,
I am picking parts for this project. Resistors first.
I am going with the larger body Vishay RN60's 1% and 50 ppm or better. There is less selection, higher price for improved % and improved ppm. If there is the option I will go for the larger RN60, + lower % and lower ppm part.
The lower % part is intuitive.
The larger body has a larger thermal mass resistive element. There is reduced temperature swing (delta t) => less thermal caused resistor distortion.
The larger body has a larger thermal mass body, cools faster, does not get as hot, produces less thermal noise.
Lower ppm works with the larger thermal mass resistive element to further reduce thermal caused resistor distortion.
Thanks DT
from APx555 testing on my bench
Exactly. My idea on going P3 is to roll those op amps. I'm sitting on V5 and both V6 Burson opamps... both single and EDIT :
My two year old P2 was pretty pricey, since it has a custom back panel with knobs to adjust everything, and the parts were the really good stuff. It sounds great, with a very, very, very low noise level, but I'm curious about the op amps.
I mean, I love how my P2 sounds... but, but....
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