What value is normal?
I'm away from my Aleph. I'll measure it on Monday.
BTW, per schematic, thermister is between AC power-line Earth and audio GND.
(I'm not sure AC power-line earth is connected to Chassis earth.)
By single-ended output design, Speaker Negative output is audio GND.
So, at normal condition, resistance of thermister should be read.
Is it correct? Then, what value is normal value?
I'm away from my Aleph. I'll measure it on Monday.
BTW, per schematic, thermister is between AC power-line Earth and audio GND.
(I'm not sure AC power-line earth is connected to Chassis earth.)
By single-ended output design, Speaker Negative output is audio GND.
So, at normal condition, resistance of thermister should be read.
Is it correct? Then, what value is normal value?
Attachments
Zen,
1) Case A: if normal CL60 (5~6ohm) resistance is measured, then what's next step?
2) Case B: if abnormal value, I need to check the connections / thermister condition, right?
One more question, when I reviewed another Class-A amp from Plinius, there is floating GND control switch. Like that, what do you think about disconnecting Earch (Chassis, power-line) from Audio GND?
1) Case A: if normal CL60 (5~6ohm) resistance is measured, then what's next step?
2) Case B: if abnormal value, I need to check the connections / thermister condition, right?
One more question, when I reviewed another Class-A amp from Plinius, there is floating GND control switch. Like that, what do you think about disconnecting Earch (Chassis, power-line) from Audio GND?
ground lift switch is pretty common thing on professional audio products ;
however , praxis is as that - licensed tech usually operates them , and ground lift is used (if needed) only when everything is connected together , and everything is on gnd potential anyway ........ so safety is maintained
you can try to solve problems upstream ...... or (on Aleph) most easily - inserting resistor of 10-22R between one input gnd and it's channel gnd ( cut gnd wire , insert resistor)
however , praxis is as that - licensed tech usually operates them , and ground lift is used (if needed) only when everything is connected together , and everything is on gnd potential anyway ........ so safety is maintained
you can try to solve problems upstream ...... or (on Aleph) most easily - inserting resistor of 10-22R between one input gnd and it's channel gnd ( cut gnd wire , insert resistor)
Thanks, Zen.
The resistance between Earth (power) and Left SPK Negative is 13.6ohm.
Interestingly, the resistance between Left SPK Neg and Right SPK Neg is 3ohm.
So, I think 3ohm is just contact resistance. (but a little big)
Then, it is around 10ohm between Earth and Audio GND.
Considering your recommendation, it should be suitable number.
So, I will try to tune my power supplying network (source, pre-amp, power-amp) at first.
If not fruitful, I'll try to add additional resister (10~20ohm) between Earth to Audio GND as you recommended.
Even in current condition, "No problem" to listen to music unless I attach my ear to speaker woofer unit.
I'm just learning audio basics to maintain my Aleph at good condition.
Thank you for your kind advises.
The resistance between Earth (power) and Left SPK Negative is 13.6ohm.
Interestingly, the resistance between Left SPK Neg and Right SPK Neg is 3ohm.
So, I think 3ohm is just contact resistance. (but a little big)
Then, it is around 10ohm between Earth and Audio GND.
Considering your recommendation, it should be suitable number.
So, I will try to tune my power supplying network (source, pre-amp, power-amp) at first.
If not fruitful, I'll try to add additional resister (10~20ohm) between Earth to Audio GND as you recommended.
Even in current condition, "No problem" to listen to music unless I attach my ear to speaker woofer unit.
I'm just learning audio basics to maintain my Aleph at good condition.
Thank you for your kind advises.
Now, I'm considering changing pre-amp, the candidate of Cary SPL-03 (tube preamp)
When I review recommended pre-amps for Aleph 0s, recommendation is a preamp with "High Gain (>20dB) and very low output impedance (<200ohm)."
Aleph 0s Balanced input
Gain: 20dB
Input impendance: 26kohm
Cary SPL-03
Gain: 16dB
Output impedance: 500ohm
Will it match, reviewing technical data? (Of course, the ideal is to match & listen but practically, I should do paper work at first.)
When I review recommended pre-amps for Aleph 0s, recommendation is a preamp with "High Gain (>20dB) and very low output impedance (<200ohm)."
Aleph 0s Balanced input
Gain: 20dB
Input impendance: 26kohm
Cary SPL-03
Gain: 16dB
Output impedance: 500ohm
Will it match, reviewing technical data? (Of course, the ideal is to match & listen but practically, I should do paper work at first.)
Per my calculation,
Output impedance 500ohm - load (input impedance) 26kohm ==> -0.165dB voltage gain loss
* Note: For audio frequency range, the magnitude of impedance of MOSET input stage is dominated by discrete resisters. 26kohm load is static over frequency/input dynamics.
Voltage Gain
8ohm, 40W = 17.88Vrms
From Source ouptut;
Voltage gain from Pre-amp to Aleph SPK out = 16 - 0.165 + 20 = 36.83dB
Pre-amp input referred voltage = (17.88V) / (36.83dB) = 289mVrms
Modern sources can supply higher than 289 mVrms ==> No problem
From Pre-amp output;
Rated output of Pre-amp = 2V, for 40W output, 19dB gain is needed. ==> No problem.
Speaker sensitivity is related to "How loud you want" per power-amp Watt.
For same loudness, smaller sensitivity, more power (power-amp)
My speaker is modern & open-duct and sensitivity is moderate.
I wondered why people were saying (200ohm output impedance, 20dB gain ...)
But I'm humble student to open ears to others' audio experiences.
Output impedance 500ohm - load (input impedance) 26kohm ==> -0.165dB voltage gain loss
* Note: For audio frequency range, the magnitude of impedance of MOSET input stage is dominated by discrete resisters. 26kohm load is static over frequency/input dynamics.
Voltage Gain
8ohm, 40W = 17.88Vrms
From Source ouptut;
Voltage gain from Pre-amp to Aleph SPK out = 16 - 0.165 + 20 = 36.83dB
Pre-amp input referred voltage = (17.88V) / (36.83dB) = 289mVrms
Modern sources can supply higher than 289 mVrms ==> No problem
From Pre-amp output;
Rated output of Pre-amp = 2V, for 40W output, 19dB gain is needed. ==> No problem.
Speaker sensitivity is related to "How loud you want" per power-amp Watt.
For same loudness, smaller sensitivity, more power (power-amp)
My speaker is modern & open-duct and sensitivity is moderate.
I wondered why people were saying (200ohm output impedance, 20dB gain ...)
But I'm humble student to open ears to others' audio experiences.
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