Tube DIY Asylum

You never stop learning

95.249.198.17

cellailuca

A

I rotate about ten tube DIY amplifiers (and a couple of commercial SS) to listen music.
While listening to this old project I turned on the smartphone 'audio scope' app.
I have done this since a long time ago with oscilloscope bud this time I suddenly realized this.
On a 40-120 millisecond time interval the audio trace is not always symmetric.
The trace has obviously zero DC but:
- 30% of time it is more positive than negative;
- 30% of time it is more negative than positive;
- 40% of time it is symmetric.
In other words real music looks totally different from test signals...

Omnes feriunt, ultima necat.

Follow Ups:

RE: You never stop learning - triode3 03:53:12 05/15/25 (0)
That is a great looking amp.

Thanks.
RE: You never stop learning - Leo loves music 07:36:16 05/08/25 (1)
I fully understand why it is not symmetric. Sometimes your environment can limit your capability to learn and to create.

Anyway I am more interested in the case/chassis of your DIY amp. Could you please show more pictures?
- RE: You never stop learning - cellailuca 07:41:40 05/08/25 (0)
  Here is the parade of all my projects since 2008.
  
  Omnes feriunt, ultima necat.
  - Thread on X (former twitter) (Open in New Window)
A 20hz signal has a 50 millisecond duration. - Chip647 07:36:01 05/08/25 (3)
If that frequency (or lower) is present at a significant level the rest of the musical signal will ride on it. Sound is propagated as a wave function and music contains all of the frequencies present in the performance. Sustained rarefaction or pressurization longer than 50 milliseconds is infrasonic sound that your speakers will likely not reproduce.

I do not believe that your phone app has revealed new physics. :-)
- The traces show a time history 40 msec long - cellailuca 07:57:06 05/08/25 (1)
  (.)
  
  Omnes feriunt, ultima necat.
  - Then, by my count, the fundamental frequency is about 250Hz. - Tre' 11:47:19 05/08/25 (0)
    .
    Have Fun and Enjoy the Music
    "Still Working the Problem"
- RE: A 20hz signal has a 50 millisecond duration. - cellailuca 07:51:28 05/08/25 (0)
  In reality there is nothing special in my observation.
  Musical instruments were selected because their notes suit fine to human brain.
  Why?
  Because of the high content of even harmonics of the fundamental tone of each note.
  High even harmonics content translates in asymmetry of electrical waveform.
  
  Omnes feriunt, ultima necat.
RE: You never stop learning - tube wrangler 07:05:50 05/08/25 (0)
We live in age of measurement of trivialities replacing
what we once had-- the ability to sense physically, and to
reason correctly-- that reasoning resulting in doing something
that is real to us-- something that our physical body,
and our spirit-- can use.
When audio equipment reproduces what we physically sense,
then it approaches world class performance because the
designer of said equipment made sure that it did.
That was accomplished by listening and then designing to
reflect the listening.
The only meaningful use of measurements was to obtain
reliability of the tools used to reproduce the listening.
The Listener and the Producer of music are the only
relevant judges of equipment that is used.
How you accomplish that is your business-- it doesn't
belong to "experts" or any of the many genuises out there--
either it works or it falls short.
--Dennis--

Edits: 05/08/25

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

VH Audio