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why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
The AMP portion should be BTL, that way there'd
be no rail-splitter mid-supply ground current.
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
The AMP portion should be BTL, that way there'd
be no rail-splitter mid-supply ground current.
The TEA2025 drives two separate stereo speakers,
a left and a right.
Don Kuenz, KB7RPU wrote...
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
The AMP portion should be BTL, that way there'd
be no rail-splitter mid-supply ground current.
The TEA2025 drives two separate stereo speakers,
a left and a right.
Stereo, yes. I'm suggesting you use a more capable
amplifier, one with complementary Bridge-Tied-Load
outputs. There is no "ground" current. Two mono
parts would be fine, but these are also available
in stereo versions. The positive current from one
output goes to the negative output of its BTL pair.
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
The AMP portion should be BTL, that way there'd
be no rail-splitter mid-supply ground current.
The TEA2025 drives two separate stereo speakers,
a left and a right.
Stereo, yes. I'm suggesting you use a more capable
amplifier, one with complementary Bridge-Tied-Load
outputs. There is no "ground" current. Two mono
parts would be fine, but these are also available
in stereo versions. The positive current from one
output goes to the negative output of its BTL pair.
In bridged mode the TEA2025 can only drive a single speaker. It takes
two TEA2025s, each in bridged mode, to drive drive stereo speakers.
Either that or find a more capable amp. It seems that the amp also
deserves its own daughterboard.
My quick and dirty solution grows more elegant by the hour. It also
becomes more interesting.
Thank you, 73,
On 6/4/19 9:13 PM, Don Kuenz wrote:
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
 The AMP portion should be BTL, that way there'd
 be no rail-splitter mid-supply ground current.
The TEA2025 drives two separate stereo speakers,
a left and a right.
 Stereo, yes. I'm suggesting you use a more capable
 amplifier, one with complementary Bridge-Tied-Load
 outputs. There is no "ground" current. Two mono
 parts would be fine, but these are also available
 in stereo versions.  The positive current from one
 output goes to the negative output of its BTL pair.
In bridged mode the TEA2025 can only drive a single speaker. It takes
two TEA2025s, each in bridged mode, to drive drive stereo speakers.
Either that or find a more capable amp. It seems that the amp also
deserves its own daughterboard.
    My quick and dirty solution grows more elegant by the hour. It also
becomes more interesting.
Thank you, 73,
If the line-level output is to be AC-coupled there should probably be a
50-100k load resistor and maybe small value cap, 100-470p, in parallel
after the coupling cap, ideally right near the output jack. And probably
a ~1k resistor in series with the coupling cap, too.
In parallel to ground, rather
Don Kuenz, KB7RPU wrote...
Winfield Hill <winfieldhill@yahoo.com> wrote:
Don Kuenz, KB7RPU wrote...
why does an audio mixer need 1.5A of available
output current?
It morphed into a mixer-amp. All will be revealed
in the upcoming webpage.
The AMP portion should be BTL, that way there'd
be no rail-splitter mid-supply ground current.
The TEA2025 drives two separate stereo speakers,
a left and a right.
Stereo, yes. I'm suggesting you use a more capable
amplifier, one with complementary Bridge-Tied-Load
outputs.
bitrex wrote...
In parallel to ground, rather
Or across the BTL load, if that was adopted.
There must be somebody on eBay or AliExpress
selling a small PCB with a stereo BTL amp.
There are certainly plenty of blokes selling
larger PCB versions, and I am a sucker for
buying various high-power class-D versions.
I imagine modifying them for DC operation,
using them to run big Peltier coolers, etc.
Or maybe I just admire their fancy heatsinks,
and in some cases towering fan assemblies.
Filling boxes with an impressive assortment.
On 6/5/19 4:08 AM, Winfield Hill wrote:
bitrex wrote...
In parallel to ground, rather
 Or across the BTL load, if that was adopted.
 There must be somebody on eBay or AliExpress
 selling a small PCB with a stereo BTL amp.
 There are certainly plenty of blokes selling
 larger PCB versions, and I am a sucker for
 buying various high-power class-D versions.
 I imagine modifying them for DC operation,
 using them to run big Peltier coolers, etc.
 Or maybe I just admire their fancy heatsinks,
 and in some cases towering fan assemblies.
 Filling boxes with an impressive assortment.
Designing and building a solid-state audio power amp is one of those
things I did one time because like, it's something a budding engineer
should probably do at least once. I guess.
I did learn quite a bit but after I was done was not eager to do it
again because for one thing there are already so many great
off-the-shelf products at relatively low cost, designed by likely far
better audio engineers than I am.
Tubes are a different story I like futzing with tubes from time to time.
BITD BTL meant "bridge transformerless".
When did that change?
Phil Hobbs wrote...
BITD BTL meant "bridge transformerless".
When did that change?
When everybody stopped using transformers?
Or started running acronyms backwards?
On 6/4/19 12:03 PM, Don Kuenz wrote:> Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
snip
I taught myself circuit design largely by reading app notes, assuming
that all the circuits were junk, and figuring out why. (Some of them
are okay, of course, but you can always think about input protection and
so forth.)
Background:
My Altoids audio mixer [1] is in the middle of a makeover. The new iso
transformer front end's already finished and sounds heavenly. New
components made my circuit outgrow the tiny Altoids tin, so now
everything's housed in a small Bud box. The new circuit utilizes a
TEA2025 stereo audio amplifier [2], among other things. That beast can
output up to 1.5 A, which far exceeds the capabilities of the TLE2426
"rail splitter" [3] that ultimately powers the new circuit. So the "rail
splitter" will drive a BUF634A buffer [4] instead, which can supply up
to 250 mA.
Spot the app note error:
My original intention was to use app notes to cobble the buffer on to
the output of the "rail splitter," easy peasy. You inspired me to spend
a little bit more time to look deeper into those app notes. Any wisdom
that you, or others, can impart on my quest to "spot the app note error"
is appreciated.
Note.
1. http://crcomp.net/electronic/altoidsmixer/index.php
2. https://media.digikey.com/pdf/Data%20Sheets/ST%20Microelectronics%20PDFS/TEA2025.pdf
3. http://www.ti.com/lit/ds/symlink/tle2426.pdf
4. http://www.ti.com/lit/ds/symlink/buf634.pdf
One of the usual appnote sins is to use gold-plated parts (their own,
naturally). This is one of those--you're using a $10 BUF634 and a $2
TLE2426 instead of a $1 TCA0372 and two resistors. (See George's thread.)
On Fri, 31 May 2019 11:48:07 +0100, Terry Pinnell wrote:
I bought my first Arduino UNO R3 kit two weeks ago (the Elegoo Super
Starter kit) and am stepping through its tutorials. In parallel I'm
trying to learn the basics of its C++ based programming language, but
that's proving a struggle.
I wouldn't even bother with C++ in this instance. Get yourself a copy of
Kernighan & Ritchie's the C Programming Language - the best book ever
written on C.
Cursitor Doom wrote:
On Fri, 31 May 2019 11:48:07 +0100, Terry Pinnell wrote:
I bought my first Arduino UNO R3 kit two weeks ago (the Elegoo Super
Starter kit) and am stepping through its tutorials. In parallel I'm
trying to learn the basics of its C++ based programming language, but
that's proving a struggle.
I wouldn't even bother with C++ in this instance. Get yourself a copy of
Kernighan & Ritchie's the C Programming Language - the best book ever
written on C.
And Harbison and Steele as number two.
On 6/12/19 8:41 AM, Peter Percival wrote:
Cursitor Doom wrote:
On Fri, 31 May 2019 11:48:07 +0100, Terry Pinnell wrote:
I bought my first Arduino UNO R3 kit two weeks ago (the Elegoo Super
Starter kit) and am stepping through its tutorials. In parallel I'm
trying to learn the basics of its C++ based programming language, but
that's proving a struggle.
I wouldn't even bother with C++ in this instance. Get yourself a copy of
Kernighan & Ritchie's the C Programming Language - the best book ever
written on C.
Agreed. My son taught himself C out of K&R just a few years back, and
liked it very well.
And Harbison and Steele as number two.
H&S was an excellent book, and I used it for several years. However,
time has moved on, and the old-time C libraries are showing their age. I
still used <cstdio>, but stuff like strdup() and realloc()? Really?
Cheers
Phil Hobbs