John Curl's Blowtorch preamplifier part II

Status
Not open for further replies.
I'm happy to acknowledge that at times digital operations, and digital to analogue and vice versa operations will introduce errors, so a copy won't be perfect. But this is where the devil enjoys climbing on board - just enough 'incorrectness' is introduced into the equation, a subtle buildup of flaws occurs; and we have audible differences popping out the end.
 
Once again I would like to emphasize that Bolton x Blomley should be investigated. This is where the change (load added) was done. We are not exploring the SRC/DAC effect, we are exploring preamp under added load condition.
And I'm happy to state that the null between those examples could be reduced to better than 60dB down by very careful alignment - hovers between 60 and 80dB through the whole clip.

The question then is, can those differences be heard ... ?
 
Sorry, that's not going to work for me. You may not recall, but I've mentioned a few times that foobar degrades the sound too much for me - a combination of my PC circuitry, and how foobar does its job causes the sound quality to be too poor to be useful.

Amazingly, there is no obvious, better alternative: I've looked several times, and there is always a problem with what's available. Just recently I came across a brand new attempt to put one together, looks promising - but I haven't seriously tried to get it working yet.

Edit: one of the underlying problems with foobar is that it generates new, resampled copies of the files for the tests - it doesn't actually use the original files ... duuuuhhhh !!
 
Last edited:
Sorry, that's not going to work for me. You may not recall, but I've mentioned a few times that foobar degrades the sound too much for me - a combination of my PC circuitry, and how foobar does its job causes the sound quality to be too poor to be useful.

Oh, I see. So the foobar degrades the sound more than SRC --> DAC --> something --> ADC path.
 
I agree that in case of slight differences it is very difficult to keep concentration and hearing resolution.
Anyway, the 50 ohm loading did not seem to introduce any harsh artifacts, in this case.

What is interesting, that sometimes people who listen with low-end equipment (like Max said, PC with 1" speakers) are able to tell the "clear difference". However, I greatly appreciate your input, that is supported with ABX foobar results.

I just burned the two tracks to cd and listened on my main system.
Same result for me, two quite different recordings, same descriptions.

Dan.

Hello Pavel.
The differences are quite distinct (Toshiba 18'' laptop, in built harman/kardon 1'' speakers)
Blomley sounds wrong...there is an unnatural attack sounds brightness/suddenness, with harmonically wrong sustains and decays.
This characteristic conspires to obscure lower level detail.
This characteristic also causes this clip to sound slightly sped up/rushed.
Is this what PRAT is referring to ?.

Bolton is the unloaded preamp output.

Dan.
 
Last edited:
Administrator
Joined 2007
Paid Member
Well...

I had another go, this time using the built in speakers on my 8 yr old Acer laptop and with volume low. It all went pear shaped in trial three because I thought I was on to something in my own mind and got over excited :D

As a very (very very) amateur pianist who has also in the past tuned my own piano using beats and intervals I thought I would try and detect anything in that department. I used just the first couple of seconds of the track.

I would like to say :yawn: (we've been here before methinks) that I was hearing something but once again maybe this just "proves" the randomness of, well, randomness and that patterns can emerge. On the other hand :eek: perhaps a little enharmonicity is creeping into Pavels loaded preamp :p)
 

Attachments

  • Acer 1.JPG
    Acer 1.JPG
    93 KB · Views: 189
  • Acer 2.JPG
    Acer 2.JPG
    58.1 KB · Views: 192
  • Acer 3.JPG
    Acer 3.JPG
    53.1 KB · Views: 191
  • Acer 4.JPG
    Acer 4.JPG
    65.2 KB · Views: 194
I'm sorry to say it, but I think you all are wasting your time. There are so many errors in producing those 'test' files, that it wery well might be that artifacts, created by the errors might be masking the real differerence between both devices under test.

Certainly, this is my opinion as well. Better say - I am sure about it.
 
Actually I agree with you on these test files.
I am not really surprised that YOUR discrete preamp, as it is properly designed and has 40ma of output quiescent current cannot be changed sonically, even with a 50 ohm load, but what about an IC with 1/2 ma Iq? Yes, that is what some 'expensive' IC's have nominally as output quiescent current. That is the equivalent to a 4K load on one of these IC's compared to your discrete preamp. So, no wonder!
Now PMA, do you now feel that discrete is unnecessary and that some of the latest IC's do the job of making line and phono stages just as well?
 

Attachments

  • Picture 12.jpg
    Picture 12.jpg
    256.3 KB · Views: 182
Last edited:
Status
Not open for further replies.