EL1254HD/T2 (red):
#1 @ 1mA: 0.36 0.35 0.35 0.34 0.35 uV
#1 @ 5mA: 0.30 0.29 0.31 0.32 0.30 uV
#1 @ 20mA: 0.51 0.56 0.54 0.55 0.53 uV
#2 @ 1mA: 0.53 0.42 0.39 0.41 0.40 uV (Vf = 1.82 V)
#2 @ 5mA: 0.30 0.30 0.31 0.29 0.29 uV (Vf = 1.90 V)
#2 @ 20mA: 0.42 0.42 0.42 0.43 0.43 uV (Vf = 2.17 V)
What you think? Realistic?
Arm is SME Series III with damping trough to accomodate low compliance cartridges. I have multiple cartridges, MM and MC, but HPS3.1 was designed to accomodate down to a very low output Orthofon (I think is 0.12uV) that I have. My favorite cartridge is currently a Benz Micro Wood SL. Speakers are 97dB Klipsch RF-83 horns, and HPS3.1 is dead silent, ear on grille, with the 0.4mV 12ohm Benz Wood. Anything else that I build or tested (even some famous models) had a slight hiss or hum. I hate hiss and hum.
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Yes with 97dB and 0.12 cart (plus more than needed line and amp gain for such speakers?) hiss and hum would be annoying. Maybe a unity gain control unit would help too?
I see you pick up some harmonic noise though on your graphs, is it penetrating the phono cable? Maybe a balanced cartridge configuration to a symmetric current stage is syn's phono 4?
I see you pick up some harmonic noise though on your graphs, is it penetrating the phono cable? Maybe a balanced cartridge configuration to a symmetric current stage is syn's phono 4?
This is a quote from: 'Low Noise Electronic Design' a textbook, p. 284
"...This unit has noise bandwidths of 200, 1000, and 3000 Hz. At these higher frequencies a wider bandwidth can be used for faster response and reduced jitter on the meter." It is the JITTER on the meter that I am referring to, as: bouncy,bouncy, bouncy'. It is just another way of expressing it, from experiencing it in real life. It must be understood that I have been measuring noise like this in audio equipment for the last 41 years. I know what to expect.
The same thing happens with the QuanTech noise analyzer. They use a 10 Hz bandwidth, rather than a 1 Hz bandwidth, in order to get a faster, smoother reading. Does everyone understand this now?
"...This unit has noise bandwidths of 200, 1000, and 3000 Hz. At these higher frequencies a wider bandwidth can be used for faster response and reduced jitter on the meter." It is the JITTER on the meter that I am referring to, as: bouncy,bouncy, bouncy'. It is just another way of expressing it, from experiencing it in real life. It must be understood that I have been measuring noise like this in audio equipment for the last 41 years. I know what to expect.
The same thing happens with the QuanTech noise analyzer. They use a 10 Hz bandwidth, rather than a 1 Hz bandwidth, in order to get a faster, smoother reading. Does everyone understand this now?
God knows, but that 5nV input harmonic noise is fortunately not audible.
HPS4.0 is almost ready and has (preliminary) about 0.27nV/rtHz noise. It's a fully bipolar construction, uses complementary transistors currently in production (from Sanyo) and the current through the cartridge can be under 250nA, depending on the beta sorting tolerance.
OK, so my device sucks, so I give up measuring? Probably. Instead, I hooked up a j201 with a 2k resistor between G and S to setup a 200uA current, and various size resistors between G and -ve. Battery 22V or so, +ve on the drain of j201. Scope lead on -ve and gate of j201. Peak-to-peak voltage noise:
470R : 10-20uV
10k : 150uV
39k : > 350uV
With a 470uF across this resistor, the noise looked below 10uV.
My scope has probably not been calibrated since day of landing on the moon; it was set to 100uV/div, so it's relatively difficult to gauge small values.
I suppose it may be best to use a real voltage reference such as the lm329 where one can, and try to avoid that capacitor. But from what I understand, one can't get rid of the cap with the lm329 either. Unfortunately I had no such reference on hand to hook it up to the scope and compare. Next installment probably.
syn08, thanks for taking the time to explain what you're doing, we learn.
John, thanks for pointing out those tricks about measurements techniques. It turns out my device isn't adequate anyway.
470R : 10-20uV
10k : 150uV
39k : > 350uV
With a 470uF across this resistor, the noise looked below 10uV.
My scope has probably not been calibrated since day of landing on the moon; it was set to 100uV/div, so it's relatively difficult to gauge small values.
I suppose it may be best to use a real voltage reference such as the lm329 where one can, and try to avoid that capacitor. But from what I understand, one can't get rid of the cap with the lm329 either. Unfortunately I had no such reference on hand to hook it up to the scope and compare. Next installment probably.
syn08, thanks for taking the time to explain what you're doing, we learn.
John, thanks for pointing out those tricks about measurements techniques. It turns out my device isn't adequate anyway.
Measuring noise with a scope is extremely imprecise and that's because a) it's not easy to estimate the average value b) you don't know exactly the bandwidth and c) you don't know the scope Y amp noise.
I'll do some measurements myself tonight (time permitting). I have all the needed devices and a 89410A plus a 3562A to compare with. I can do 0.001Hz RBW (overnight) without any "bouncings", in fact all the noise measurements on my web site are at 0.1Hz RBW or less.
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