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Townsend Isolda cable
- Thread starter Purité Audio
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- Mar 22, 2019
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In Internet slang, a troll is a person who starts flame wars or intentionally upsets people on the Internet by posting inflammatory and digressive,[1] extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the intent of provoking readers into displaying emotional responses[2] and normalizing tangential discussion,[3] either for the troll's amusement, or to achieve a specific result such as disrupting a rival's online activities or manipulating a political process.
- Joined
- Mar 22, 2019
- Messages
- 127
- Likes
- 28
We cannot conclude anything from the posted plots. Why 2 of the same plots ?
A: We don't know if the dummy load or a resistor was used as a load.
B: mr. Townshend should have made a reference measurement where the input of the ADC should be connected to the output of the amp so we get a real reference in the form of the sweep. The 55.5mV says nothing, we don't know how sensitive the ADC was set, we don't know if the voltage level is referenced.
C: mr Townshend conveniently forgot to mention the cable length as well. (this could have given a clue about calibration)
D: About the dummy load: The posted schematic won't have the impedance posted alongside. Amir's sim is better. Why is the plot from mr Townshend incorrect or the schematic is incorrect (has a Boucherot filter installed ?)
E: Why not a comparo between regular speaker cable and the Isolda instead of the single strip of isolda cable which measures FAR worse that any speaker cable.
A: We don't know if the dummy load or a resistor was used as a load.
B: mr. Townshend should have made a reference measurement where the input of the ADC should be connected to the output of the amp so we get a real reference in the form of the sweep. The 55.5mV says nothing, we don't know how sensitive the ADC was set, we don't know if the voltage level is referenced.
C: mr Townshend conveniently forgot to mention the cable length as well. (this could have given a clue about calibration)
D: About the dummy load: The posted schematic won't have the impedance posted alongside. Amir's sim is better. Why is the plot from mr Townshend incorrect or the schematic is incorrect (has a Boucherot filter installed ?)
E: Why not a comparo between regular speaker cable and the Isolda instead of the single strip of isolda cable which measures FAR worse that any speaker cable.
Again very poor test protocol.
a better plan:
a] attach 'cable under test' from the amp to the speaker or dummy load.
b] with the Fluke measuring across the amps terminals. using a 1000 Hz tone, set the amps output level at 1.90 V RMS.
c] measure the voltage at the speaker's terminals.
d] run a frequency response curve at the amp's terminals.
e] without changing any settings, run a frequency response curve at the speaker's terminals.
f] repeat with another cable.
a better plan:
a] attach 'cable under test' from the amp to the speaker or dummy load.
b] with the Fluke measuring across the amps terminals. using a 1000 Hz tone, set the amps output level at 1.90 V RMS.
c] measure the voltage at the speaker's terminals.
d] run a frequency response curve at the amp's terminals.
e] without changing any settings, run a frequency response curve at the speaker's terminals.
f] repeat with another cable.
Where do you see "70uV at 20Hz"? And how is 70uV cable loss 23dB of a 55mV input voltage?
Update/Correction, didn't notice you mentioned 20Hz and not 20kHz (I was focused on 10kHz and higher where you have the highest loss). But the question remains; "how is 70uV cable loss 23dB of a 55mV input voltage"?
Update/Correction, didn't notice you mentioned 20Hz and not 20kHz (I was focused on 10kHz and higher where you have the highest loss). But the question remains; "how is 70uV cable loss 23dB of a 55mV input voltage"?
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Why not disclose what you did, mention lengths, use a clear reference ?
How can we repeat the measurements when I don't want to buy 7m Isolda cable and YOU provide the measurements.
Are you being vague on purpose ?
The 55.5mV is pointless as a reference when you use white noise upto 20kHz as the Fluke won't register correctly above 500Hz ...
Totally not scientific at all.
Why not do this with 'normal' speaker cable with the same DC resistance ?
How can we repeat the measurements when I don't want to buy 7m Isolda cable and YOU provide the measurements.
Are you being vague on purpose ?
The 55.5mV is pointless as a reference when you use white noise upto 20kHz as the Fluke won't register correctly above 500Hz ...
Totally not scientific at all.
Why not do this with 'normal' speaker cable with the same DC resistance ?
Without a real reference we have to trust him... Given the track record of being vague and incomplete ... 
(There might be some error margin on the 55.5mV input voltage, but that error would need to be really huge to get a 23dB cable loss).
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