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The sound of parts

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#61
Dorkus, why not try something simple? Say, a simple passive HP filter at 10 Hz. One made from whatever premium parts you like, one made from crappy Radio Shack parts of the same values. I'll be happy to set the test up for you, build and pot the modules, code them, then give the score sheet to a third party (sensory research is a big part of what I get paid for in my day job).

The test could be done several ways. One is to build up 10 boxes, 5 of each type, and have you sort them into goats or sheep (if you can sort them correctly, I won't care if you can tell which is the "good" set). Another is to make 10 sets of boxes, some of which have A and B the same, some of which have A and B different and have you sort on that basis (same or different, again, not caring which is "better"). Another is to make 10 sets of three boxes each; each set is a "triangle" with two matching and one oddball.

In all cases, there would be a master or reference set, the identities of which you know, so that you can verify what differences you're hearing.

How does that sound? (bad pun)
 
#62
dhaen said:

It's true that Push Pull, and negative feedback both, in their seperate ways can be used to "mask" the effects of poor quality components or design. But only so far. It all comes out in the wash. That does not mean they are "evil". Just that there is a time and a place.
Click to expand...

Hi John,

You are so wrong!

They are evil and followers of that topology should be burned on the stake!!!!!!!

😉

Cheers,
Bas
 
#63
that sounds ok, although i don't know if a simple HP filter (really just a cap) is enough to be a good test. better to have a circuit with a more parts, to test the cummulative effect. also, just 2 boxes will suffice - if you send me 10 i will get fed up just switching between the damn things all the time and not care anymore.
 
#64
Distortion

When voltage negative feedback is applied, the ouput impedance is lowered - this is normally a benefit. Also the Total Harmonic Distortion figure falls. Unfortunately (and this depends on the design & the topology), the higher order harmonics can actually increase in amplitude.
So, although the figures are better, it can sound worse.
 
#65
SY, another idea... wire up two circuits in one chassis, and have an 8-position switch. wire the outputs of the two circuits randomly to the switch - e.g. circuit #1 could be on 2, 3, 5, and 8, while #2 could be on 1, 4, 6, and 7. before you wire it up tho, i would like to check the circuits to see they're set up properly, or hvae an independent 3rd party like Peter Daniel check it. then you can wire it up at random, and i can test. this is better and more reliable than having 8 separate boxes.
 
#67
AGREED AGAIN

Hi,

So, although the figures are better, it can sound worse.
Click to expand...

The pursuit of good looking measurement figures can throw the baby out together with the water.(Don't quite remember how the expression goes)

Another phenomenon to consider is time delayed distortion when using FB,as is phase rotation.

better to have a circuit with a more parts, to test the cummulative effect. also, just 2 boxes will suffice - if you send me 10
Click to expand...

Tests like this should be carried out using one item at the time IMO.
If you listen to one resistor or a circuit built around a dozen of them the net subjective impression won't necessarily be the same.

Ciao,😉
 
#74
Dorkus: You need more than two boxes- after all, a stopped clock is right twice a day. Multiple trials are necessary to reduce the vagaries of chance.

Your switch idea is fine, though I don't want to hear complaints afterwards about how the switch contacts were sooooo degrading that they cover up the differences you're trying to hear. I like relays for ABX switching, but there's nothing wrong with a good old-fashioned rotary switch.

I can have anyone you like here in the Bay Area verify proper operation before I pot up the assembly. Even Nelson Pass, if he'll contribute the time- I'm only an hour or so away from him. If he'll participate, I'll let him keep a copy of the master key sheet.
 
#80
How he (or I, for that matter) "feels" about passives is irrelevant- as long as he's someone competent to judge if I've wired it up the way I say I did (zero question about THAT) and is a person whose integrity we all trust (ditto). And that he's reachable within a reasonable driving time from my house.
 
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