Wireless ?

[Bill Lampman]

Hi,

I'm trying to install a wireless system. Are there any wireless
transmitter/receiver
combinations that allow standard wired speakers to be wireless? I mean are
there
any wireless receivers with built-in amps for driving standard speakers, or
must
wireless speakers be used ?

If I can only go with wireless speakers, what are the best ones ?

Bill

[Scott Dorsey]

Bill Lampman > wrote:
>
> I'm trying to install a wireless system. Are there any wireless
>transmitter/receiver
>combinations that allow standard wired speakers to be wireless? I mean are
>there
>any wireless receivers with built-in amps for driving standard speakers, or
>must
>wireless speakers be used ?

No, the problem is that a power amplifier requires a good deal of
current. You can get an IFB receiver that will drive headphones nicely,
but if you want to drive speakers, you need a reasonable amount of power
and that means you need to plug it into the wall, which defeats the whole
idea of wireless.

You could have an IFB receiver driving a power amp run off a small
generator. I have seen this done for delay stacks at concerts.

> If I can only go with wireless speakers, what are the best ones ?

Good ones do not exist.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[ric]

Scott Dorsey wrote:

> No, the problem is that a power amplifier requires a good deal of
> current. You can get an IFB receiver that will drive headphones nicely,
> but if you want to drive speakers, you need a reasonable amount of power
> and that means you need to plug it into the wall, which defeats the whole
> idea of wireless.

Well, no. It doesn't. It still eliminates the need (and logistics) of
running thick gauge speaker wire from the amplifier to the distant room.

[Scott Dorsey]

In article >, ric > wrote:
>Scott Dorsey wrote:
>
>> No, the problem is that a power amplifier requires a good deal of
>> current. You can get an IFB receiver that will drive headphones nicely,
>> but if you want to drive speakers, you need a reasonable amount of power
>> and that means you need to plug it into the wall, which defeats the whole
>> idea of wireless.
>
>Well, no. It doesn't. It still eliminates the need (and logistics) of
>running thick gauge speaker wire from the amplifier to the distant room.

So, put the amplifier in the distant room and run thin gauge line level
cable. No wireless needed.

Or run 70V system.

Going wireless is just such a huge can of worms that it's best to avoid
opening it unless you absolutely have to.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Crowley]

"Scott Dorsey" > wrote in message
...
> Bill Lampman > wrote:
> >
> > I'm trying to install a wireless system. Are there any wireless
> >transmitter/receiver
> >combinations that allow standard wired speakers to be wireless? I mean
are
> >there
> >any wireless receivers with built-in amps for driving standard speakers,
or
> >must
> >wireless speakers be used ?
>
> No, the problem is that a power amplifier requires a good deal of
> current. You can get an IFB receiver that will drive headphones nicely,
> but if you want to drive speakers, you need a reasonable amount of power
> and that means you need to plug it into the wall, which defeats the whole
> idea of wireless.
>
> You could have an IFB receiver driving a power amp run off a small
> generator. I have seen this done for delay stacks at concerts.
>
> > If I can only go with wireless speakers, what are the best ones ?
>
> Good ones do not exist.

Over on news:rec.arts.movies.production.sound, an engineer from
Lectrosonics said they were working with a (some?) powered
speaker vendor(s) to use Lectro's digital wireless receiver plugged
into the accessory slot. (Like maybe my Mackie SRM-350s, etc?)

Of course, that is a commercial solution and possibly well out of the
(unstated?) budget range of Mr. Lampman. And still requires mains
power, of course.

[Richard Crowley]

"Scott Dorsey" wrote...
> Going wireless is just such a huge can of worms that it's best to avoid
> opening it unless you absolutely have to.

Hear! Hear! Here!

[Pooh Bear]

Bill Lampman wrote:

> Hi,
>
> I'm trying to install a wireless system. Are there any wireless
> transmitter/receiver
> combinations that allow standard wired speakers to be wireless? I mean are
> there
> any wireless receivers with built-in amps for driving standard speakers, or
> must
> wireless speakers be used ?
>
> If I can only go with wireless speakers, what are the best ones ?

An interesting area since it's one I'm loosely involved in. And may be
developing for.

Wireless transmission of high quality audio is bandwidth intensive. To date I'm
still unaware of anything capable of transmitting and receiving CD quality
audio. There are ppl working on it though in the same 'license free' band as
wireless networking etc....

There are Bluetooth audio headsets and stuff out there but they are strictly
low-fi. Normally using 64kbits/sec which after 'overheads' associated with RF
signal redundancy probably sound a bit like 32kbits/sec mp3.

Graham

[Pooh Bear]

ric wrote:

> Scott Dorsey wrote:
>
> > No, the problem is that a power amplifier requires a good deal of
> > current. You can get an IFB receiver that will drive headphones nicely,
> > but if you want to drive speakers, you need a reasonable amount of power
> > and that means you need to plug it into the wall, which defeats the whole
> > idea of wireless.
>
> Well, no. It doesn't. It still eliminates the need (and logistics) of
> running thick gauge speaker wire from the amplifier to the distant room.

You still need a *power* cable though !

Don't be too distant btw. 2.4GHz @ the allowed transmit level gets mopped up
pretty fast.

Graham

[Pooh Bear]

Scott Dorsey wrote:

> In article >, ric > wrote:
> >Scott Dorsey wrote:
> >
> >> No, the problem is that a power amplifier requires a good deal of
> >> current. You can get an IFB receiver that will drive headphones nicely,
> >> but if you want to drive speakers, you need a reasonable amount of power
> >> and that means you need to plug it into the wall, which defeats the whole
> >> idea of wireless.
> >
> >Well, no. It doesn't. It still eliminates the need (and logistics) of
> >running thick gauge speaker wire from the amplifier to the distant room.
>
> So, put the amplifier in the distant room and run thin gauge line level
> cable. No wireless needed.
>
> Or run 70V system.
>
> Going wireless is just such a huge can of worms that it's best to avoid
> opening it unless you absolutely have to.

There's been no shortage off ppl 'announcing' wireless hi-fi audio without
remotely having the product available that I got into a full blown row with a
potential business partner over this.

He was *convinced* that his 'mates' knew what they were talking about. He said "
my brother works in semiconductors - you're just being negative " etc blah -
blah - blah and what-not.

His brother does indeed. I'd previously asked him for any helpful contacts. He'd
mentioned Cirrus logic.

When I got Cirrus Logic's PR guy to mail my 'friend' to the effect that they had
dropped all interest in that product area he *finally* shut up.

Graham

[Richard Crowley]

"Pooh Bear" wrote ...
> There's been no shortage off ppl 'announcing' wireless hi-fi
> audio without remotely having the product available that I
> got into a full blown row with a potential business partner
> over this.

There are some pretty cool RF modules over at www.sparkfun.com
Likely wouldn't be terribly difficult to interface to A\D and D/A
converters to make a high-quality digital wireless link.

[Pooh Bear]

Richard Crowley wrote:

> "Pooh Bear" wrote ...
> > There's been no shortage off ppl 'announcing' wireless hi-fi
> > audio without remotely having the product available that I
> > got into a full blown row with a potential business partner
> > over this.
>
> There are some pretty cool RF modules over at www.sparkfun.com
> Likely wouldn't be terribly difficult to interface to A\D and D/A
> converters to make a high-quality digital wireless link.

Interesting link ( more for the other stuff actually ). Can any of them
handle a 1.4 Mbps ( CD audio quality ) link with no errors ?

I suspect they may fail regulatory requirements anyway. I also rather
doubt they use frequency hopping to ensure a clear pathway.

Graham

[Kalman Rubinson]

On Sat, 11 Jun 2005 15:49:57 +0100, Pooh Bear
> wrote:

>Richard Crowley wrote:
>
>> "Pooh Bear" wrote ...
>> > There's been no shortage off ppl 'announcing' wireless hi-fi
>> > audio without remotely having the product available that I
>> > got into a full blown row with a potential business partner
>> > over this.
>>
>> There are some pretty cool RF modules over at www.sparkfun.com
>> Likely wouldn't be terribly difficult to interface to A\D and D/A
>> converters to make a high-quality digital wireless link.
>
>Interesting link ( more for the other stuff actually ). Can any of them
>handle a 1.4 Mbps ( CD audio quality ) link with no errors ?
>
>I suspect they may fail regulatory requirements anyway. I also rather
>doubt they use frequency hopping to ensure a clear pathway.

Do a search for Sonetteer. They showed several devices which meet
that criterion including a receiver with a built-in power amp.

Kal

[ric]

Pooh Bear wrote:

> > > No, the problem is that a power amplifier requires a good deal of
> > > current. You can get an IFB receiver that will drive headphones nicely,
> > > but if you want to drive speakers, you need a reasonable amount of power
> > > and that means you need to plug it into the wall, which defeats the whole
> > > idea of wireless.
> >
> > Well, no. It doesn't. It still eliminates the need (and logistics) of
> > running thick gauge speaker wire from the amplifier to the distant room.
>
> You still need a *power* cable though !

Yes, but the AC outlet can be close to the speaker, whereas the speaker
wire itself would have to be brought from another room.

[ric]

Pooh Bear wrote:

> > There are some pretty cool RF modules over at www.sparkfun.com
> > Likely wouldn't be terribly difficult to interface to A\D and D/A
> > converters to make a high-quality digital wireless link.
>
> Interesting link ( more for the other stuff actually ). Can any of them
> handle a 1.4 Mbps ( CD audio quality ) link with no errors ?

I think "FM radio" quality is a more realistic goal for wireless
speakers.

[Pooh Bear]

ric wrote:

> Pooh Bear wrote:
>
> > > There are some pretty cool RF modules over at www.sparkfun.com
> > > Likely wouldn't be terribly difficult to interface to A\D and D/A
> > > converters to make a high-quality digital wireless link.
> >
> > Interesting link ( more for the other stuff actually ). Can any of them
> > handle a 1.4 Mbps ( CD audio quality ) link with no errors ?
>
> I think "FM radio" quality is a more realistic goal for wireless
> speakers.

CD quality links are in the pipeline - trust me. I can't say too much since I
signed an NDA.

Graham

[Pooh Bear]

Kalman Rubinson wrote:

> On Sat, 11 Jun 2005 15:49:57 +0100, Pooh Bear
> > wrote:
>
> >Richard Crowley wrote:
> >
> >> "Pooh Bear" wrote ...
> >> > There's been no shortage off ppl 'announcing' wireless hi-fi
> >> > audio without remotely having the product available that I
> >> > got into a full blown row with a potential business partner
> >> > over this.
> >>
> >> There are some pretty cool RF modules over at www.sparkfun.com
> >> Likely wouldn't be terribly difficult to interface to A\D and D/A
> >> converters to make a high-quality digital wireless link.
> >
> >Interesting link ( more for the other stuff actually ). Can any of them
> >handle a 1.4 Mbps ( CD audio quality ) link with no errors ?
> >
> >I suspect they may fail regulatory requirements anyway. I also rather
> >doubt they use frequency hopping to ensure a clear pathway.
>
> Do a search for Sonetteer. They showed several devices which meet
> that criterion including a receiver with a built-in power amp.

I wonder whose product they're using. I'll have to get up to date with the
company I know that's working on it.

Graham

[Scott Dorsey]

Richard Crowley > wrote:
>
>Over on news:rec.arts.movies.production.sound, an engineer from
>Lectrosonics said they were working with a (some?) powered
>speaker vendor(s) to use Lectro's digital wireless receiver plugged
>into the accessory slot. (Like maybe my Mackie SRM-350s, etc?)
>
>Of course, that is a commercial solution and possibly well out of the
>(unstated?) budget range of Mr. Lampman. And still requires mains
>power, of course.

Lectro stuff is about as good as it gets, and it's still very audibly
different than a straight wire. But I have seen Lectro and Vega
IFB packs used for delay stacks at festivals (with generators at the
base of the stack).

It only takes one CBer with a dirty linear a few miles down the road
the screw everything up, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Pooh Bear > wrote:
>
>Wireless transmission of high quality audio is bandwidth intensive. To date I'm
>still unaware of anything capable of transmitting and receiving CD quality
>audio. There are ppl working on it though in the same 'license free' band as
>wireless networking etc....

Actually, a cheap trick we have used has been to take the inexpensive
transmitter/receiver pairs from the X-10 system which are intended for
passing video around the home, and running S-PDIF audio through them.

We have successfully shot S-PDIF from one building to the next in downtown
Baltimore just by pointing the things out the windows. Channel reliability
wasn't the best and I'd worry a lot about rain fade, but it worked better
than I'd expected and it allowed us to get good quality audio around.

>There are Bluetooth audio headsets and stuff out there but they are strictly
>low-fi. Normally using 64kbits/sec which after 'overheads' associated with RF
>signal redundancy probably sound a bit like 32kbits/sec mp3.

There's no reason you can't get as much bandwidth as you want, as long
as you're willing to pay for it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Karl Winkler]

Scott Dorsey wrote:
> Pooh Bear > wrote:
> >
> >Wireless transmission of high quality audio is bandwidth intensive. To date I'm
> >still unaware of anything capable of transmitting and receiving CD quality
> >audio. There are ppl working on it though in the same 'license free' band as
> >wireless networking etc....
>
> Actually, a cheap trick we have used has been to take the inexpensive
> transmitter/receiver pairs from the X-10 system which are intended for
> passing video around the home, and running S-PDIF audio through them.
>
> We have successfully shot S-PDIF from one building to the next in downtown
> Baltimore just by pointing the things out the windows. Channel reliability
> wasn't the best and I'd worry a lot about rain fade, but it worked better
> than I'd expected and it allowed us to get good quality audio around.
>
> >There are Bluetooth audio headsets and stuff out there but they are strictly
> >low-fi. Normally using 64kbits/sec which after 'overheads' associated with RF
> >signal redundancy probably sound a bit like 32kbits/sec mp3.
>
> There's no reason you can't get as much bandwidth as you want, as long
> as you're willing to pay for it.
> --scott

We're using a proprietary method, developed in-house, that gets very
close to 88.2kHz, 20-bit quality (with actually measureable 107dB s/n)
into the standard FCC FM mask requirements for bandwidth in the UHF
region. The audio is not companded, but instead we use a unique DSP
process to treat the audio before transmission. It is not identical to
a cable, but most users tend to say that it is the closest thing on the
market. And it's not terribly expensive anymore, since we are starting
to sell a lot of it, and have made some stripped-down products
recently. And unlike most network-based methods, ours only has latency
of 3.2mS.

/spam

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

[Carey Carlan]

(Scott Dorsey) wrote in
:

> We have successfully shot S-PDIF from one building to the next in
> downtown Baltimore just by pointing the things out the windows.
> Channel reliability wasn't the best and I'd worry a lot about rain
> fade, but it worked better than I'd expected and it allowed us to get
> good quality audio around.

How did you convert spdif to a video signal?

[Arny Krueger]

Carey Carlan wrote:
> (Scott Dorsey) wrote in
> :
>
>> We have successfully shot S-PDIF from one building to the
next in
>> downtown Baltimore just by pointing the things out the
windows.
>> Channel reliability wasn't the best and I'd worry a lot
about rain
>> fade, but it worked better than I'd expected and it
allowed us to get
>> good quality audio around.
>
> How did you convert spdif to a video signal?

SP/DIF and video are very similar signals. Both are 1 volt
p-p @ 75 ohms. In theory 24/96 SP/DIF has somewhat greater
bandwidth requirements than NTSC video, but 24/44 is far
closer at around 6-8 MHz.

[Scott Dorsey]

In article >,
Carey Carlan > wrote:
(Scott Dorsey) wrote in
:
>
>> We have successfully shot S-PDIF from one building to the next in
>> downtown Baltimore just by pointing the things out the windows.
>> Channel reliability wasn't the best and I'd worry a lot about rain
>> fade, but it worked better than I'd expected and it allowed us to get
>> good quality audio around.
>
>How did you convert spdif to a video signal?

I didn't. It's a square wave with a 4KHz bandwidth or so. It went
right into the device as if it were video... it doesn't care about
synch configuration or anything. Just like using video DIs for
distributing S-PDIF audio around.

It doesn't meet the specs... the received signal has a lot more jitter
than it should because the edges are rounded a little, but the DAC locked
up nicely to it and it worked out fine. I wouldn't want to rely on it
for anything I was getting paid for or put my reputation up on, but for
home use it seems a fine cheap way of moving digital audio around.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Arny Krueger wrote:
> Carey Carlan wrote:
>> (Scott Dorsey) wrote in
>> :
>>
>>> We have successfully shot S-PDIF from one building to the
>>> next in downtown Baltimore just by pointing the things out
>>> the windows. Channel reliability wasn't the best and I'd
>>> worry a lot about rain fade, but it worked better than I'd
>>> expected and it allowed us to get good quality audio around.
>>
>> How did you convert spdif to a video signal?
> SP/DIF and video are very similar signals. Both are 1 volt
> p-p @ 75 ohms. In theory 24/96 SP/DIF has somewhat greater
> bandwidth requirements than NTSC video, but 24/44 is far
> closer at around 6-8 MHz.

Indeed, if do a little hostorical research, you'll discover that
the choice of 44.1 kHz sample rate was dictated by the fact that
the only large-capacity storage devices for digital audio at the
time (late '70s) were video recorders. The sample rate was chosen
such that an integral number of frames could be stored on each
scan line.

For example, take NTSC video with its 525 lines and 60 Hz field
rate. Assume 35 blanked lines, that leaves 490 lines per frame,
or 245 lines pere field. There's plenty of bandwidth to fit 3
samples per scan line, so:

60 fld/s * 245 lin/fls * 3 sample/lin = 44,100 samples/s

For 625 lines @50 Hz, you have 37 blanked lines, levaing 588
lines/frame or 294 per field, 3 samples per line, and you get

50 fld/s * 294 lin/fls * 3 sample/lin = 44,100 samples/s

Clever, eh?

The point being that, yes, while it can be said that digital audio
signal are a lot like video signals, at one time, they WERE video
signals (and still are, it's just that there aren't a lot of
video recorders being used for this purpose any more).

The issues mentioned of jitter and the like could be remedied by
a properly design DAC where the D/A clock is not tied intimately
to theincoming bit rate. The longer-term average, on the order
of several millieseconds, is quite stable and accurate over this
sort of a link, while the bit-level timing could well be off by a
bit.

[[email protected]]

Scott Dorsey wrote:
> In article >,
> Carey Carlan > wrote:
> (Scott Dorsey) wrote in
> :
> >
> >> We have successfully shot S-PDIF from one building to the next in
> >> downtown Baltimore just by pointing the things out the windows.
> >> Channel reliability wasn't the best and I'd worry a lot about rain
> >> fade, but it worked better than I'd expected and it allowed us to get
> >> good quality audio around.
> >
> >How did you convert spdif to a video signal?
>
> I didn't. It's a square wave with a 4KHz bandwidth or so.

Uh, actually, more like 2.8 MHz.

S/P-DIF has 32 bits/sample subframe, 4 bits header/preamble,
24 bits usable audio data, 4 bits channel status, user status,
validy and parity bits. Two subframes per sample frame, 44,100
sample frames per second, thus:

32*2*44100 = 2,822,400 bits/second

And since it's biphase-encoded, it's essentially a square wave
per bit.

All perfectly suited for transmission via standard video channels.

[Joe Kesselman]

Scott Dorsey wrote:
> Actually, a cheap trick we have used has been to take the inexpensive
> transmitter/receiver pairs from the X-10 system which are intended for
> passing video around the home, and running S-PDIF audio through them.

I knew I remembered talking with someone who had done this and couldn't
recall who. Not sure if it was you or not, but at least this confirms I
wasn't dreaming it. Thanks for the crosscheck.

[Pooh Bear]

wrote:

> Scott Dorsey wrote:
> > In article >,
> > Carey Carlan > wrote:
> > (Scott Dorsey) wrote in
> > :
> > >
> > >> We have successfully shot S-PDIF from one building to the next in
> > >> downtown Baltimore just by pointing the things out the windows.
> > >> Channel reliability wasn't the best and I'd worry a lot about rain
> > >> fade, but it worked better than I'd expected and it allowed us to get
> > >> good quality audio around.
> > >
> > >How did you convert spdif to a video signal?
> >
> > I didn't. It's a square wave with a 4KHz bandwidth or so.
>
> Uh, actually, more like 2.8 MHz.
>
> S/P-DIF has 32 bits/sample subframe, 4 bits header/preamble,
> 24 bits usable audio data, 4 bits channel status, user status,
> validy and parity bits. Two subframes per sample frame, 44,100
> sample frames per second, thus:
>
> 32*2*44100 = 2,822,400 bits/second
>
> And since it's biphase-encoded, it's essentially a square wave
> per bit.
>
> All perfectly suited for transmission via standard video channels.

The bitrate and the *bandwidth* required to reliably send / receive aren't the
same though.

Graham

[Joe Kesselman]

Pooh Bear wrote:
> The bitrate and the *bandwidth* required to reliably send / receive aren't the
> same though.

In this case, I'd say experimental evidence makes the point moot. "If it
happens, it must be possible."

[Scott Dorsey]

In article >,
Joe Kesselman > wrote:
>Scott Dorsey wrote:
>> Actually, a cheap trick we have used has been to take the inexpensive
>> transmitter/receiver pairs from the X-10 system which are intended for
>> passing video around the home, and running S-PDIF audio through them.
>
>I knew I remembered talking with someone who had done this and couldn't
>recall who. Not sure if it was you or not, but at least this confirms I
>wasn't dreaming it. Thanks for the crosscheck.

I got the idea from Dave Josephson, who saw it at the Strawberry Festival.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Pooh Bear]

Joe Kesselman wrote:

> Pooh Bear wrote:
> > The bitrate and the *bandwidth* required to reliably send / receive aren't the
> > same though.
>
> In this case, I'd say experimental evidence makes the point moot. "If it
> happens, it must be possible."

But the video sender surely has more than 2.8 MHz bandwidth ?

Graham