Jon Anderson wrote:

I work from home and have a fairly nice shop stereo setup, a
90 watt JVC tuner/amp, cd player, tape player, and I run the
shop tv through the 2nd tape input. With some nice Roger
Sound Labs studio monitor speakers, I can hear music or news
over shop noise. Just undertook a couple minor upgrades. I
added a set of small metal case Optimus speakers for TV, as
the big speakers have too much bass. That worked great,
until I tried upgrade #2. I listen to Pandora.com when
working at my computer, and wanted to run the output into
the stereo so I can listen to my custom stations while
working. I only have phono left for input, but wasn't sure
it would work, so using an 1/8 to RCA adapter, I plugged in
my MP3 player. Still running through the Optimus speakers
and probably a good thing. There was a hell of a loud noise
that only slightly resembled the Robin Trower song playing,
then the speakers went dead. They are both deader than
doornails. I know the amp will output far more than they
will handle, but I had the volume way down. Seems like maybe
the input was more than a bit higher than it should be and
thus the output was as well? (luckily the Optimus speakers
came out of a yard sale free pile...)

Anyway, since a sound card will output to speakers or
headphones equally well, I assumed the test would validate
hooking up the computer before running wires across the
shop. I'd still like to do this, but it sure seems there's
some mismatch between what a sound card/MP3 player puts out
and what a phono input wants to see. Is there a quick and
easy way to match up the signals? Or should I just make up a
switch box and switch the the input from the computer with
one of the other inputs I'm already using.

Thanks,

Jon


Does it have a tape monitor input? The phono input are easy to
overload, and have a RIAA filter that will make it sound odd.


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Jon Anderson wrote:
I work from home and have a fairly nice shop stereo setup, a 90 watt JVC
tuner/amp, cd player, tape player, and I run the shop tv through the 2nd
tape input. With some nice Roger Sound Labs studio monitor speakers, I
can hear music or news over shop noise. Just undertook a couple minor
upgrades. I added a set of small metal case Optimus speakers for TV, as
the big speakers have too much bass. That worked great, until I tried
upgrade #2. I listen to Pandora.com when working at my computer, and
wanted to run the output into the stereo so I can listen to my custom
stations while working. I only have phono left for input, but wasn't
sure it would work, so using an 1/8 to RCA adapter, I plugged in my MP3
player. Still running through the Optimus speakers and probably a good
thing. There was a hell of a loud noise that only slightly resembled the
Robin Trower song playing, then the speakers went dead. They are both
deader than doornails. I know the amp will output far more than they
will handle, but I had the volume way down. Seems like maybe the input
was more than a bit higher than it should be and thus the output was as
well? (luckily the Optimus speakers came out of a yard sale free pile...)

Anyway, since a sound card will output to speakers or headphones equally
well, I assumed the test would validate hooking up the computer before
running wires across the shop. I'd still like to do this, but it sure
seems there's some mismatch between what a sound card/MP3 player puts
out and what a phono input wants to see. Is there a quick and easy way
to match up the signals? Or should I just make up a switch box and
switch the the input from the computer with one of the other inputs I'm
already using.

Thanks,

Jon

The problem is that you CANNOT use the phono inputs. They feed into a
small preamp and equalizer circuit (likely that is fried now because of
the high signal level you used). That is the big noise you heard. If you
still have output from the amp then your lucky. What you will want to do
is feed the sound card into the same inputs as the TV Tape or other
external unit. You will need an input selector switch to prevent any
signal problems.

--
Steve W.
Near Cooperstown, New York

Life is not like a box of chocolates
it's more like a jar of jalapenos-
what you do today could burn your ass tomorrow!


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I work from home and have a fairly nice shop stereo setup, a
90 watt JVC tuner/amp, cd player, tape player, and I run the
shop tv through the 2nd tape input. With some nice Roger
Sound Labs studio monitor speakers, I can hear music or news
over shop noise. Just undertook a couple minor upgrades. I
added a set of small metal case Optimus speakers for TV, as
the big speakers have too much bass. That worked great,
until I tried upgrade #2. I listen to Pandora.com when
working at my computer, and wanted to run the output into
the stereo so I can listen to my custom stations while
working. I only have phono left for input, but wasn't sure
it would work, so using an 1/8 to RCA adapter, I plugged in
my MP3 player. Still running through the Optimus speakers
and probably a good thing. There was a hell of a loud noise
that only slightly resembled the Robin Trower song playing,
then the speakers went dead. They are both deader than
doornails. I know the amp will output far more than they
will handle, but I had the volume way down. Seems like maybe
the input was more than a bit higher than it should be and
thus the output was as well? (luckily the Optimus speakers
came out of a yard sale free pile...)

Anyway, since a sound card will output to speakers or
headphones equally well, I assumed the test would validate
hooking up the computer before running wires across the
shop. I'd still like to do this, but it sure seems there's
some mismatch between what a sound card/MP3 player puts out
and what a phono input wants to see. Is there a quick and
easy way to match up the signals? Or should I just make up a
switch box and switch the the input from the computer with
one of the other inputs I'm already using.

Thanks,

Jon

The Phono input is VERY low level-apx 120MV @1KHZ-you can't input a
line-level signal without overdriving the preamp, possibly damaging
the output drivers, or as you found out, output devices. Your 'e lucky
the tuner still works.
JR
Dweller in the cellar

On Fri, 03 Oct 2008 20:16:09 -0800, Jon Anderson
wrote:

I work from home and have a fairly nice shop stereo setup, a
90 watt JVC tuner/amp, cd player, tape player, and I run the
shop tv through the 2nd tape input. With some nice Roger
Sound Labs studio monitor speakers, I can hear music or news
over shop noise. Just undertook a couple minor upgrades. I
added a set of small metal case Optimus speakers for TV, as
the big speakers have too much bass. That worked great,
until I tried upgrade #2. I listen to Pandora.com when
working at my computer, and wanted to run the output into
the stereo so I can listen to my custom stations while
working. I only have phono left for input, but wasn't sure
it would work, so using an 1/8 to RCA adapter, I plugged in
my MP3 player. Still running through the Optimus speakers
and probably a good thing. There was a hell of a loud noise
that only slightly resembled the Robin Trower song playing,
then the speakers went dead. They are both deader than
doornails. I know the amp will output far more than they
will handle, but I had the volume way down. Seems like maybe
the input was more than a bit higher than it should be and
thus the output was as well? (luckily the Optimus speakers
came out of a yard sale free pile...)

Anyway, since a sound card will output to speakers or
headphones equally well, I assumed the test would validate
hooking up the computer before running wires across the
shop. I'd still like to do this, but it sure seems there's
some mismatch between what a sound card/MP3 player puts out
and what a phono input wants to see. Is there a quick and
easy way to match up the signals? Or should I just make up a
switch box and switch the the input from the computer with
one of the other inputs I'm already using.

Thanks,

Jon
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
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others may have answered -
1. DO NOT use the phono input - it is designed for a low level signal (a few
milivolts) and has a RIAA equalization curve - even if you drop the level
low enough, you will have only low end because of the equalization curve.

2. you probably burned out the speakers with a massive burst of power

3. use AUX, Tape, or some other high level input. If needed, add a switch
box.

4. amps with a phono input are higly desireable - consider selling it and
buying a nice new amp with lots of high level inputs if you don't need phono


** Posted from http://www.teranews.com **

Michael A. Terrell wrote:

Does it have a tape monitor input? The phono input are easy to
overload, and have a RIAA filter that will make it sound odd.

Two tape inputs. One used for the tape deck, the other is
used for the TV/DVD player. I moved the stereo to a more
accessible spot, I can just swap cables from the
computer/tape deck until I get around to making a switch
box. I'd hoped to match the signals, but even that would be
a stretch for my electronics skills, trying to undo that
filter is more than I am going to mess with....

Thanks!!

Jon

Steve W. wrote:

If you still have output from the amp then your lucky.

I am lucky then. The amp was a $5 score so it wouldn't have
been a big financial loss, but good tuner/amps don't show up
at yard sales for $5 very often...

You will need an input selector switch to prevent any
signal problems.

Ah, cool. Sounds like I can buy this then instead of having
to make one up.

Thanks!


Jon

On Fri, 03 Oct 2008 20:16:09 -0800, Jon Anderson
wrote:

I work from home and have a fairly nice shop stereo setup, a
My shop stereo setup consists of a pocket CD player with AM, FM, TV
audio and weather radio tuner from Aiwa (Sony?) that I got for $2
feeding powered computer speakers $1. Considering that I worked on
airports for 20+ years without hearing protection, it sounds pretty
good to me as long as I turn it up enough to drown out the tinnitus.
Gerry :-)}
London, Canada

Jon Anderson writes:

I'd still like to do this, but it sure seems there's
some mismatch between what a sound card/MP3 player puts out
and what a phono input wants to see. Is there a quick and
easy way to match up the signals?

You've discovered a little-known and very prescient DRM system built into
every record player and high-fidelity system from the 1950s on. Plugging
MP3 sound into a phono input will permanently destroy crucial circuitry.
This is known as "RIAA equalization": you "steal" their music downloading
MP3s, they waste your hifi. This was cleverly disguised as a tonal
characteristic for many decades of the pre-digital era.

Be glad your MP3 player still works. They were also supposed to self-
destruct when connected to a RIAA-equalized antique port, but the Chinese
manufacturers fouled up the feature and it triggers on very few models.

This is also backwards-compatible. If you connect a phono cartridge to
your PC to digitize your vinyl record collection, it triggers a backfeed
that scribbles "Millenium Copyright Act VIOLATION" onto the record using
the diamond stylus.

Richard J Kinch wrote:

This is also backwards-compatible. If you connect a phono cartridge to
your PC to digitize your vinyl record collection, it triggers a backfeed
that scribbles "Millenium Copyright Act VIOLATION" onto the record using
the diamond stylus.

The sad thing is if the RIAA could do this, they would.

Wes

"Wes" wrote in message
...
Richard J Kinch wrote:

This is also backwards-compatible. If you connect a phono cartridge to
your PC to digitize your vinyl record collection, it triggers a backfeed
that scribbles "Millenium Copyright Act VIOLATION" onto the record using
the diamond stylus.

The sad thing is if the RIAA could do this, they would.

Wes

even sadder, it is inherently impossible to make a copy protection system
for audio reproduction that is not trivial to defeat with an analog
recorder. So all they can do is make it slower to copy, and of course chase
after students and grand parents who download songs.

But this has precious little to do with metalworking

BUT!!! there is one GREAT metalworking idea that we can now divert to - it
is in fact the reason I bought a mill, a lathe, and all sorts of tooling -
the world needs a reasonably priced NON-CONTACT phonograph player. There
are some that cost $$$, but it seems to me with a CD reading head (actually
two) or a laser and a couple of detector arrays, some prisims and a bunch of
really fun machining to make a servo driven tone arm, one should be able to
extract the grove information ENTIRELY in the analog domain, no
digitization.

So, let's talk about how we could build that??? (and it would not need RIAA
equalization, but it would need some other kind)


** Posted from http://www.teranews.com **

William Noble wrote:

2. you probably burned out the speakers with a massive burst of power
Looks like maybe the speakers are OK. It looks like I blew
the preamp for the 2nd speaker outputs. Of course, I know
next to nothing how these things operate, but cranked to
full power, I can just barely hear the Optimus speakers, and
they are faint but clear. The other speaker outputs are fine.

3. use AUX, Tape, or some other high level input. If needed, add a switch
box.
All other inputs currently used, so I'm looking for a switch
now.


4. amps with a phono input are higly desireable - consider selling it and
buying a nice new amp with lots of high level inputs if you don't need phono
This was a $5 amp/tuner, and it might be desirable to a tech
for spare parts, but it's seen better days. I had thoughts
of finding a decent turntable at a yard sale, just so I
could record a few albums I have that are highly unlikely to
end up on CD. But then ran across some USB turntables that
would allow direct recording to a Windoze compatible format.
That beats cassette tape for sure!

Like the thought of your non-contact turntable. That would
be slick...


Jon

On Fri, 03 Oct 2008 21:30:51 -0700, JR North
wrote:

The Phono input is VERY low level-apx 120MV @1KHZ-you can't input a
line-level signal without overdriving the preamp, possibly damaging
the output drivers, or as you found out, output devices. Your 'e lucky
the tuner still works.
JR
Dweller in the cellar


Most good electonics shops have Attenuators, a form of resistor that
will take that big signal, and drop it down to a much much smaller
signal

The ones Ive used over the years had an RCA male/female on the ends
and they simply plugged in between the two devices.


"Obama, raises taxes and kills babies. Sarah Palin - raises babies
and kills taxes." Pyotr Flipivich

William Noble writes:

There
are some that cost $$$, but it seems to me with a CD reading head
(actually two) or a laser and a couple of detector arrays, some
prisims and a bunch of really fun machining to make a servo driven
tone arm, one should be able to extract the grove information ENTIRELY
in the analog domain, no digitization.

The reason that costs $$$ is that even though it might be a fun hobby
project, if you're capable of doing that sort of wonderful thing as a
hobby, people will be waving $$$ at you to do their non-hobby projects
instead.

"William Noble" wrote:


BUT!!! there is one GREAT metalworking idea that we can now divert to - it
is in fact the reason I bought a mill, a lathe, and all sorts of tooling -
the world needs a reasonably priced NON-CONTACT phonograph player. There
are some that cost $$$, but it seems to me with a CD reading head (actually
two) or a laser and a couple of detector arrays, some prisims and a bunch of
really fun machining to make a servo driven tone arm, one should be able to
extract the grove information ENTIRELY in the analog domain, no
digitization.

So, let's talk about how we could build that??? (and it would not need RIAA
equalization, but it would need some other kind)

I'm assuming you have read this page? http://en.wikipedia.org/wiki/Laser_turntable

Wes

On Sat, 04 Oct 2008 15:50:22 -0400, Wes wrote:
"William Noble" wrote:

BUT!!! there is one GREAT metalworking idea that we can now divert to - it
is in fact the reason I bought a mill, a lathe, and all sorts of tooling -
the world needs a reasonably priced NON-CONTACT phonograph player. There
are some that cost $$$, but it seems to me with a CD reading head (actually
two) or a laser and a couple of detector arrays, some prisims and a bunch of
really fun machining to make a servo driven tone arm, one should be able to
extract the grove information ENTIRELY in the analog domain, no
digitization.

So, let's talk about how we could build that??? (and it would not need RIAA
equalization, but it would need some other kind)

I'm assuming you have read this page? http://en.wikipedia.org/wiki/Laser_turntable

I have a CD Dub of an old LP album made from one of these Laser
Turntable beauties, and it's clean and crisp as the (long missing)
studio master - and considering the original instrument used was a
'Honky Tonk' piano deliberately tuned slightly atonal and the felt
hammer heads hardened with lacquer to give a real 'tack piano' sound,
it was no easy task.

Oh, and it would still need RIAA Equalization at playback, since at
the record mastering studio they boosted the treble and reduced the
bass to the cutting stylus to keep the bass notes from blowing out
into the next track over. And it happened anyway if one track's Zig
perfectly coincided with the next one's Zag. They would increase the
feed on the cutting lathe dynamically for that section and try cutting
the master again.

Without the EQ curve added at recording properly subtracted again at
playback, the results would be thin and reedy with no bottom.

-- Bruce --

Bruce L. Bergman wrote:

Oh, and it would still need RIAA Equalization at playback, since at
the record mastering studio they boosted the treble and reduced the
bass to the cutting stylus to keep the bass notes from blowing out
into the next track over. And it happened anyway if one track's Zig
perfectly coincided with the next one's Zag. They would increase the
feed on the cutting lathe dynamically for that section and try cutting
the master again.


I'm feeling old. I knew about the track issues with large amplitude signals a long, long,
time ago.

I also can see my turntable from where I'm typing along with the record shelf.


Wes

My almost new Sony Turntable has a switch underneath near the gears.
This switches from magnetic pickups to line out levels.

This works great with the line out - into my CD recorder and from that
to my TV/amplifier inputs. The TV has internal AV/High Def amps.

The 3 year old - amplifier went to the shop! Shop is high def converted
down to video. The amp is AM/FM/5+ speaker type. I lost the antenna feed
in the storm so the radio keeps the background working for me.

Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


William Noble wrote:
others may have answered -
1. DO NOT use the phono input - it is designed for a low level signal (a few
milivolts) and has a RIAA equalization curve - even if you drop the level
low enough, you will have only low end because of the equalization curve.

2. you probably burned out the speakers with a massive burst of power

3. use AUX, Tape, or some other high level input. If needed, add a switch
box.

4. amps with a phono input are higly desireable - consider selling it and
buying a nice new amp with lots of high level inputs if you don't need phono


** Posted from http://www.teranews.com **


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On 2008-10-04, Jon Anderson wrote:

[ ... ]

working. I only have phono left for input, but wasn't sure
it would work, so using an 1/8 to RCA adapter, I plugged in
my MP3 player. Still running through the Optimus speakers
and probably a good thing. There was a hell of a loud noise
that only slightly resembled the Robin Trower song playing,
then the speakers went dead. They are both deader than
doornails. I know the amp will output far more than they
will handle, but I had the volume way down.

Not possible to have it down enough. Phono inputs are for
signal levels around perhaps 15 mV, while the line level inputs (same
connector) are for levels around 1.0 V or so -- sometimes more. That is
a gain of 50X or so. I don't think that your volume control has a
position lowe enough to make this work -- even neglecting the distortion
which would come from overdriving the input stage that much. (The input
stage is before the volume control, so it can't protect that part.)

To add to the problems, the signal to the line level inputs is
presumed to be fairly flat in frequency response. However, the output
of a good phono cartridge has a serious frequency variation, so the gain
varies with frequency to adjust the level properly. At one time (late
1950s), there were quite a few different equalization curves, now we are
down to a single one for all brands of records -- I think.

What you *really* need is a box which will switch a selection of
inputs into a single input of your amplifier. So -- you set the
amplifier/preamp to "AUX" or "AUX1" or whatever you have available, and
then operate the switch on the separate box. It would probably be
beneficial to have volume controls for each input so you don't get a
major jump in volume as you switch from input to input. If you can get
away without the individual volume controls, all you need is a metal
box (aluminium is fine), two phono jacks for each input, and a pair for
the output, plus a two pole rotary switch with enough positions to
handle the number of input you need -- plus one or two spares for when
you find other things which you need.

But stay clear of the phono inputs with anything but the
connectors from a turntable with a phono cartridge. (If you have the
schematics of your amplifier and a reasonable knowledge of electronics,
you could bypass the phono preamp stages and go directly to the switch
inside there -- but I would not do this to a nice amplifier/preamp (or
receiver).

Anyway, since a sound card will output to speakers or
headphones equally well,

A lot of computer speakers have small amplifiers inside them, so
you are not really directly driving the speakers from the sound card.
If the speakers have a wall wart which needs to be plugged in to make
them work, they have the amplifier.

I assumed the test would validate
hooking up the computer before running wires across the
shop. I'd still like to do this, but it sure seems there's
some mismatch between what a sound card/MP3 player puts out
and what a phono input wants to see.

A major mismatch, as described above. :-)

Is there a quick and
easy way to match up the signals?

If you are capable of designing an attenuator circuit with the
inverse of the equalization curve in the phone preamp -- you could do
this -- but ...

Or should I just make up a
switch box and switch the the input from the computer with
one of the other inputs I'm already using.

That is the way to go.

Good Luck,
DoN.

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