Boost signal strength to transducers?

[Dave]

I recently purchased a Sony DX255 home theater system and wanted to be able to replace their subwoofer with 4 aura 25-watt, 4-ohm transducers. According to the specs, the subwoofer output was rated at ~275 watts @ 4 ohms, which I thought would be plenty to drive the transducers. Either I am misunderstanding the specs, or they are highly overrated as the output from the receiver is barely enough to drive one transducer! So I am looking for an alternative way to hook up the transducers. I figured I would get an amp specifically to drive the transducers, but there are NO audio out's on the Sony system! The only audio output is via the speaker outs. (Well, there is a headphone jack, but using this disables the speakers, so it does not count.)

Is there a way to take the audio signal from the speaker output and boost it so that it can drive the transducers? Does anyone know what product will do this?

*thanks*

Dave

[Arny Krueger]

"Dave" > wrote in message
news:20072170357.439582@dave

> I recently purchased a Sony DX255 home theater system and
> wanted to be able to replace their subwoofer with 4 aura
> 25-watt, 4-ohm transducers.

AFAIK, shakers don't generally replace subwoofers, they augment them.

> According to the specs, the
> subwoofer output was rated at ~275 watts @ 4 ohms, which
> I thought would be plenty to drive the transducers.

Usually the power amp for the subwoofer is in the subwoofer. That's what the
specs mean by "8-inch active subwoofer". The power amp in the subwoofer
can only power the subwoofer cabinet that it is in.

> Either I am misunderstanding the specs, or they are
> highly overrated as the output from the receiver is
> barely enough to drive one transducer!

Actually, the subwoofer output of the receiver should be incapable of
directly driving any speakers at all. Instead, you need an external power
amp. Such an amplifier might be the Berhinger A500.

> So I am looking
> for an alternative way to hook up the transducers. I
> figured I would get an amp specifically to drive the
> transducers, but there are NO audio out's on the Sony
> system!

> The only audio output is via the speaker outs.


According to the specs, there is subwoofer pre out on the receiver. I'd
expect it to be be a RCA jack.

> (Well, there is a headphone jack, but using this disables
> the speakers, so it does not count.)


> Is there a way to take the audio signal from the speaker
> output and boost it so that it can drive the transducers?
> Does anyone know what product will do this?

According to the specs, there is subwoofer pre out on the receiver. I'd
expect it to be be a RCA jack.

[Dave]

On Sat, 17 Feb 2007 10:21:29 -0500, "Arny Krueger" >
wrote:

>"Dave" > wrote in message
>news:20072170357.439582@dave
>
>> I recently purchased a Sony DX255 home theater system and
>> wanted to be able to replace their subwoofer with 4 aura
>> 25-watt, 4-ohm transducers.
>
>AFAIK, shakers don't generally replace subwoofers, they augment them.

I agree, but in this situation I want to replace the subwoofer.

>> According to the specs, the
>> subwoofer output was rated at ~275 watts @ 4 ohms, which
>> I thought would be plenty to drive the transducers.
>
>Usually the power amp for the subwoofer is in the subwoofer. That's what the
>specs mean by "8-inch active subwoofer". The power amp in the subwoofer
>can only power the subwoofer cabinet that it is in.

I'm not sure we are looking at the same specs--the Sony DAV-DX255 is
here:

http://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/SY_DisplayProductInformation-Start?CategoryName=hav_HomeTheater_DVDDreamSystems&ProductSKU=DAVDX255&TabName=specs&var2=

>
>> Either I am misunderstanding the specs, or they are
>> highly overrated as the output from the receiver is
>> barely enough to drive one transducer!
>
>Actually, the subwoofer output of the receiver should be incapable of
>directly driving any speakers at all. Instead, you need an external power
>amp. Such an amplifier might be the Berhinger A500.

I just looked at it, but there are only the following inputs:

"Input connections on balanced XLR, 1/4" TRS and RCA connectors"

Since there are no audio outputs on the DX255, I would need something
that could take the signal from the speaker output, boost it and then
drive the 4-ohm transducers. At least, that is the only game plan I
can think of at this point.

>> So I am looking
>> for an alternative way to hook up the transducers. I
>> figured I would get an amp specifically to drive the
>> transducers, but there are NO audio out's on the Sony
>> system!
>
>> The only audio output is via the speaker outs.
>
>
>According to the specs, there is subwoofer pre out on the receiver. I'd
>expect it to be be a RCA jack.

I looked, both in the specs and physically on the unit, but do not see
that, so I am thinking that we might be looking at two different
systems. I wish that there was a pre-out! :(

Do you know of a way to amplify the signal using the speaker out's?

[Richard Crowley]

"Dave" wrote ...
> Do you know of a way to amplify the signal using the speaker out's?

The car audio people sell little "adapters" (actually simple pads)
that take speaker outputs and allow connection to conventional
line inputs on power amps, etc. It is simple enough to do. Like...
http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743

If the amplifier is inside the subwoofer box, you will have to break
it open to access the speaker signal. Of course, if you are doing
that, you have access to the power amp output (to run directly
to your transducers) or the line-level signal (to run to your amp
for the transducers), etc. etc.

Note that the rated impedance of that subwoofer is very non-
standard. (1.5 ohms) That would be a red flag to me that it
is a very tightly-integrated and customized system, not very
conducive to modifications as you are suggesting.

IMHO, your plan for replacing the subwoofer of a low-end
system with transducers seems pretty doubtful. From what
we have read here, you seem to be in over your head and
you run the risk of blowing the subwoofer amp. Those systems
are not very easy to modify even by experienced technicians.

[Dave]

On Sat, 17 Feb 2007 09:49:17 -0800, "Richard Crowley"
> wrote:

>"Dave" wrote ...
>> Do you know of a way to amplify the signal using the speaker out's?
>
>The car audio people sell little "adapters" (actually simple pads)
>that take speaker outputs and allow connection to conventional
>line inputs on power amps, etc. It is simple enough to do. Like...
>http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743
>
>Note that the rated impedance of that subwoofer is very non-
>standard. (1.5 ohms) That would be a red flag to me that it
>is a very tightly-integrated and customized system, not very
>conducive to modifications as you are suggesting.
>
>IMHO, your plan for replacing the subwoofer of a low-end
>system with transducers seems pretty doubtful. From what
>we have read here, you seem to be in over your head and
>you run the risk of blowing the subwoofer amp. Those systems
>are not very easy to modify even by experienced technicians.

It does not appear that the amp is in the subwoofer and I think I can
use the speaker out directly from the receiver. *But*, I appreciate
your note of caution because as you mention, this field is not my
strength. And the last thing I want to do is blow out the receiver if
it cannot provide enough power to drive the transducers.

With that said, does your reticence still hold true if I am able to
use the above speaker-to-RCA adapter on speaker-out from the receiver,
plug the RCA jacks into an amp that will then power the transducers?
Meaning, I could use the subwoofer output directly from the receiver
and feed that into an amp.

However... looking at the adapters, I see the following warning:

"Not recommended for use with high power head units (over 15 watts)."

Would this apply to my situation?

Really appreciate your feedback!

[Dave]

On Sat, 17 Feb 2007 09:49:17 -0800, "Richard Crowley"
> wrote:

>"Dave" wrote ...
>> Do you know of a way to amplify the signal using the speaker out's?
>
>The car audio people sell little "adapters" (actually simple pads)
>that take speaker outputs and allow connection to conventional
>line inputs on power amps, etc. It is simple enough to do. Like...
>http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743

I found this: http://www.logjamelectronics.com/soundlocsuba.html

"The Soundgate LOCSUBA is a 2-channel, passive device that is designed
to provide an easy connection of a subwoofer system to the speakers of
an existing radio. The plastic encased enclosure measures 1 7/8" x 1
3/8" x 1". Two color-coded pairs of wires are used for the input from
the new receiver or CD player, and two RCA connectors provide the
outputs to the new subwoofer amplifier/s. The LOCSUBA features a
built-in low pass crossover bass boost centered at 50Hz, a built-in
infrasonic filter below 20Hz, a volume control that varies the output
level from 0V to a max 9.5V RMS and most importantly....no noise!!
Your new receiver's speaker wires connect to the LOCSUBA and then the
LOCSUBA is connected to your amplifier/s using the RCA connectors and
a RCA patch cord (sold separately)."

Is this a better option than the 15-watt adapters from Parts Express,
or is the 15-watt one sufficient?

There are some other adapters rated up to 85 Watts, although, again, I
am not sure that they are high enough for my needs. I wonder if it
may be because the level coming out of this receiver simply does not
seem to be as strong as the specs would suggest.

[Arny Krueger]

"Dave" > wrote in message

> On Sat, 17 Feb 2007 10:21:29 -0500, "Arny Krueger"
> > wrote:
>
>> "Dave" > wrote in message
>> news:20072170357.439582@dave
>>
>>> I recently purchased a Sony DX255 home theater system
>>> and wanted to be able to replace their subwoofer with 4
>>> aura 25-watt, 4-ohm transducers.
>>
>> AFAIK, shakers don't generally replace subwoofers, they
>> augment them.
>
> I agree, but in this situation I want to replace the
> subwoofer.
>
>>> According to the specs, the
>>> subwoofer output was rated at ~275 watts @ 4 ohms, which
>>> I thought would be plenty to drive the transducers.
>>
>> Usually the power amp for the subwoofer is in the
>> subwoofer. That's what the specs mean by "8-inch active
>> subwoofer". The power amp in the subwoofer can only
>> power the subwoofer cabinet that it is in.
>
> I'm not sure we are looking at the same specs--the Sony
> DAV-DX255 is here:
>
> http://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/SY_DisplayProductInformation-Start?CategoryName=hav_HomeTheater_DVDDreamSystems&ProductSKU=DAVDX255&TabName=specs&var2=

Right, the subwoofer is attached to the receiver via a proprietary means
called a Sony "DAV connector".

How is the existing subwoofer attached to the receiver? Wire? Wireless? if
via wire, what kind of wire and attached to what on the receiver?


>>> Either I am misunderstanding the specs, or they are
>>> highly overrated as the output from the receiver is
>>> barely enough to drive one transducer!

>> Actually, the subwoofer output of the receiver should be
>> incapable of directly driving any speakers at all.
>> Instead, you need an external power amp. Such an
>> amplifier might be the Berhinger A500.

> I just looked at it, but there are only the following
> inputs:

> "Input connections on balanced XLR, 1/4" TRS and RCA
> connectors"

I found more information here - looks like a very similar device:

http://www.amazon.com/gp/product/product-description/B000ES8C2G/ref=dp_proddesc_0/105-1725804-3046031?ie=UTF8&n=172282&s=electronics

Note
"Inputs/Outputs - Audio In (2)/Out (1) Front Input - AV A/V In (4)/Out (1)
Monitor Out (1) Component Video In (2)/Out (1) (HD Pass-Through) 5.1
Multi-channel In (1) HDMI Digital In (2)/Out (1) (Switcher) Optical Digital
In (2) Coaxial Digital In (1) Subwoofer Pre Out (1)"

Note the last item.


> Since there are no audio outputs on the DX255, I would
> need something that could take the signal from the
> speaker output, boost it and then drive the 4-ohm
> transducers. At least, that is the only game plan I can
> think of at this point.

The subwoofer doesn't work via intuition or telepathy, does it? ;-)

It must be driven via some kind of audio output.

>>> So I am looking
>>> for an alternative way to hook up the transducers. I
>>> figured I would get an amp specifically to drive the
>>> transducers, but there are NO audio out's on the Sony
>>> system!

>>> The only audio output is via the speaker outs.

>> According to the specs, there is subwoofer pre out on
>> the receiver. I'd expect it to be be a RCA jack.

> I looked, both in the specs and physically on the unit,
> but do not see that, so I am thinking that we might be
> looking at two different systems. I wish that there was
> a pre-out! :(

How does the audio signal get to the existing subwoofer?

> Do you know of a way to amplify the signal using the
> speaker out's?

Yes - Richard Crowly nailed it.

[Arny Krueger]

"Richard Crowley" > wrote in message

> "Dave" wrote ...
>> Do you know of a way to amplify the signal using the
>> speaker out's?
>
> The car audio people sell little "adapters" (actually
> simple pads) that take speaker outputs and allow
> connection to conventional line inputs on power amps, etc. It is simple
> enough to
> do. Like...
> http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743

> If the amplifier is inside the subwoofer box, you will
> have to break it open to access the speaker signal. Of
> course, if you are doing that, you have access to the
> power amp output (to run directly to your transducers) or the line-level
> signal (to run to
> your amp for the transducers), etc. etc.

But there may be any number of problems with doing that.

> Note that the rated impedance of that subwoofer is very
> non- standard. (1.5 ohms) That would be a red flag to me
> that it is a very tightly-integrated and customized system, not
> very conducive to modifications as you are suggesting.

Good point.

> IMHO, your plan for replacing the subwoofer of a low-end
> system with transducers seems pretty doubtful. From what
> we have read here, you seem to be in over your head and
> you run the risk of blowing the subwoofer amp. Those
> systems are not very easy to modify even by experienced
> technicians.

Agreed.

[Richard Crowley]

"Dave" wrote ...
> It does not appear that the amp is in the subwoofer and I think I can
> use the speaker out directly from the receiver. *But*, I appreciate
> your note of caution because as you mention, this field is not my
> strength. And the last thing I want to do is blow out the receiver if
> it cannot provide enough power to drive the transducers.
>
> With that said, does your reticence still hold true if I am able to
> use the above speaker-to-RCA adapter on speaker-out from the receiver,
> plug the RCA jacks into an amp that will then power the transducers?
> Meaning, I could use the subwoofer output directly from the receiver
> and feed that into an amp.

I would certainly NOT attempt to run the receiver without
the subwoofer speaker attached as they designed it.

> However... looking at the adapters, I see the following warning:
> "Not recommended for use with high power head units (over 15 watts)."
> Would this apply to my situation?

If you could attach it to the wiring between the power amp
and the subwoofer speaker, it would be worth trying. The
worst you could is to burn out the adapter. I would certainly
NOT try to operate your receiver without the subwoofer
speaker attached.

HOWEVER, trying to *replace* a subwoofer with those
kind of transducers just seems goofy and doomed to certain
failure, IMHO. If you can afford those transducers, I would
think that investing the same $$$ in a better receiver/speakers
would be more advisable. I really can't stress enough how
BAD this idea is IMHO.

[Richard Crowley]

"Dave" wrote ...
> I found this: http://www.logjamelectronics.com/soundlocsuba.html
>
> Is this a better option than the 15-watt adapters from Parts Express,
> or is the 15-watt one sufficient?

It is more expensive. Likely because it has things like
crossovers which you don't need, and volume control,
which you may not need, either.

> There are some other adapters rated up to 85 Watts, although, again, I
> am not sure that they are high enough for my needs. I wonder if it
> may be because the level coming out of this receiver simply does not
> seem to be as strong as the specs would suggest.

You are correct to question the "specs" of plastic consumer
systems like that one, even with the "Sony" badge on it.

It is difficult to answer any of your questions definitively
because of the proprietary nature of systems like that.
They were not designed to be interconnected as you are
proposing and it takes more than blindly plugging in a few
gadgets and adapters and hoping for the best. You really
are in over your head on a questionable experiment.
I would NOT recommend that you proceed.

[Dave]

On Sat, 17 Feb 2007 14:25:02 -0800, "Richard Crowley"
> wrote:

>If you could attach it to the wiring between the power amp
>and the subwoofer speaker, it would be worth trying. The
>worst you could is to burn out the adapter. I would certainly
>NOT try to operate your receiver without the subwoofer
>speaker attached.

Short of tearing open the subwoofer box, there are no out's from the
subwoofer.

>HOWEVER, trying to *replace* a subwoofer with those
>kind of transducers just seems goofy and doomed to certain
>failure, IMHO. If you can afford those transducers, I would
>think that investing the same $$$ in a better receiver/speakers
>would be more advisable. I really can't stress enough how
>BAD this idea is IMHO.

lol... okay! Point taken. I should have posted my question *before*
buying this system. While I thought I did a reasonable job checking
the specs, there were still too many unknowns. Lesson learned.

So... question: if I wanted to get a different system that would have
low-end theater capabilities (I don't need some costing huge $$$'s)
*and* be able to drive 4 transducers, are there any suggestions for
such a system?

The transducers are 50-watt RMS 4-ohm each, which can be hooked up in
series are parallel, whichever would be necessary for the system.

[Dave]

On Sat, 17 Feb 2007 14:08:19 -0500, "Arny Krueger" >
wrote:

>Right, the subwoofer is attached to the receiver via a proprietary means
>called a Sony "DAV connector".
>
>How is the existing subwoofer attached to the receiver? Wire? Wireless? if
>via wire, what kind of wire and attached to what on the receiver?

All the speakers and subwoofer are attached using regular 16-gauge
speaker wire. The "DAV connector" is what they use to plug the wire
into the receiver instead of binding posts. It looks kind of like a
phone plug snap on one end of the write (which plugs into the
receiver) and two raw/stripped wires at the other end (which plug into
the speakers/subwoofer).

>> Since there are no audio outputs on the DX255, I would
>> need something that could take the signal from the
>> speaker output, boost it and then drive the 4-ohm
>> transducers. At least, that is the only game plan I can
>> think of at this point.
>
>The subwoofer doesn't work via intuition or telepathy, does it? ;-)

Heh... at this point I think that would probably be easier. :)

>It must be driven via some kind of audio output.

Yes--regular 16-gauge speaker wire.

At this point, I am going to look into different systems that can
(hopefully) offer the same price-point, or close to it, as the Sony
system and yet accomodates the 4 transducers. Please let me know if
you have any suggestions for such a system.

And thanks to both you and Richard for all your helpful insights.
Besides saving me from probably ruining a perfectly good home theater
system, you've given me some very helpful directions. Thanks, again,
to both of you.

[Mr.T]

"Dave" > wrote in message
...
> All the speakers and subwoofer are attached using regular 16-gauge
> speaker wire. The "DAV connector" is what they use to plug the wire
> into the receiver instead of binding posts. It looks kind of like a
> phone plug snap on one end of the write (which plugs into the
> receiver) and two raw/stripped wires at the other end (which plug into
> the speakers/subwoofer).

> At this point, I am going to look into different systems that can
> (hopefully) offer the same price-point, or close to it, as the Sony
> system and yet accomodates the 4 transducers. Please let me know if
> you have any suggestions for such a system.

So why a new system when all you need is a suitable power amp to drive those
transducers, and feed those "stripped wires" to the power amp inputs via a
simple two resistor attenuator.
Whether the performance will be what you are after is another matter
entirely though.

MrT.

[Dave]

On Sun, 18 Feb 2007 16:03:29 +1100, "Mr.T" <MrT@home> wrote:

>> At this point, I am going to look into different systems that can
>> (hopefully) offer the same price-point, or close to it, as the Sony
>> system and yet accomodates the 4 transducers. Please let me know if
>> you have any suggestions for such a system.
>
>So why a new system when all you need is a suitable power amp to drive those
>transducers, and feed those "stripped wires" to the power amp inputs via a
>simple two resistor attenuator.
>Whether the performance will be what you are after is another matter
>entirely though.

When you say "two resistor attenuator" -- you are referring to the
these high/low adapters? :

http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743

And Richard noted concern with running these speaker wired-outs from
the receiver to the amp. I'm not 100% clear as to why, but this is
not my area of expertise.

And as far as performance, all the transducers need to do is convey
the low frequencies with sufficient strength and rumble. :)

[Richard Crowley]

"Dave" wrote ...
> When you say "two resistor attenuator" -- you are referring to the
> these high/low adapters? :
>
> http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743

Yes, those "high/low adapters" I cited are just 2-resistor
attenuators.

> And Richard noted concern with running these speaker wired-outs from
> the receiver to the amp. I'm not 100% clear as to why, but this is
> not my area of expertise.

Running the receiver without all the speakers attached
as designed is something I would avoid. With those
integrated receiver/speaker things, you don't know what
kind of dependencies, etc. you are dealing with.

> And as far as performance, all the transducers need to do is convey
> the low frequencies with sufficient strength and rumble. :)

If you really want to do that, tapping into the subwoofer
speaker line with one of those attenuator/adapters would
appear to be safe for the Sony receiver, then feed the
resulting line-level sub-woofer signal into another power
amplifier that just feeds your transducers.

[Mr.T]

"Richard Crowley" > wrote in message
...
> "Dave" wrote ...
> > When you say "two resistor attenuator" -- you are referring to the
> > these high/low adapters? :
> >
> >
http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID
=743
>
> Yes, those "high/low adapters" I cited are just 2-resistor
> attenuators.
>
> > And Richard noted concern with running these speaker wired-outs from
> > the receiver to the amp. I'm not 100% clear as to why, but this is
> > not my area of expertise.
>
> Running the receiver without all the speakers attached
> as designed is something I would avoid. With those
> integrated receiver/speaker things, you don't know what
> kind of dependencies, etc. you are dealing with.

I have never seen a problem with running a solid state amp into an open
circuit, however there is probably no reason why you wouldn't just run the
speakers as well.


> If you really want to do that, tapping into the subwoofer
> speaker line with one of those attenuator/adapters would
> appear to be safe for the Sony receiver, then feed the
> resulting line-level sub-woofer signal into another power
> amplifier that just feeds your transducers.

Which is what I was suggesting all along.

MrT.

[Barry Mann]

Sometimes the attenuators are sold as a "Z-coupler".

In my opinion, those transducers will augment, not replace a subwoofer.
They can add an interesting little "bump" to the floor or chair.

If you want to keep that SONY, use a Z-coupler and an old cast off
receiver to power the transducers.

With any decent receiver, all you'll have is a line out for the
subwoofer and you'll need an external amplifier for the transducers
anyway.

-----------------------------------------------------------
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[[email protected]]

On Feb 18, 10:17 pm, (Barry Mann) wrote:
> Sometimes the attenuators are sold as a "Z-coupler".
>

Only ever saw them referred to as a Z Coupler by Carver. Mine works
quite well, but I've often wondered if it somehow adds any distortion
or other audible anomalies. I've never heard any ill effects, but
then again, my hearing probably isn't the best.

Jeff

[Barry Mann]

In . com>, on 02/24/07

at 07:18 PM, " > said:

>On Feb 18, 10:17 pm, (Barry Mann) wrote:
>> Sometimes the attenuators are sold as a "Z-coupler".
>>

>Only ever saw them referred to as a Z Coupler by Carver. Mine works
>quite well, but I've often wondered if it somehow adds any distortion
>or other audible anomalies. I've never heard any ill effects, but
>then again, my hearing probably isn't the best.

It's not the worst thing that could happen to an audio signal, but it
does mean that the signal has already had one trip though an inadequate
amplifier (otherwise, why would you be adding yet another ampifier?)

Quite often I think that these things are designed by the cleaning lady
because the internal resistor values are calculated such that the whole
thing burns up if the first amplifier supplies a voltage that would
result in more than a few Watts of output.

-----------------------------------------------------------
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wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
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