Replacing dual-coil speaker with single?

[Ken_B]

I recently acquired a 1995 Gran Prix. The 6x9 rear speakers are very weak
and I was thinking of replacing them with a nice pair of Jensens I have.

But the Jensens only have one coil, whereas the ones in the car have two:
4-ohm and 10-ohm. I don't know the rating on the Jensens (model J310TX) -
they are not marked and I can't find any specs on the Internet.

Any advice?

[MOSFET]

OK, first a little Car Audio 101. The voice coils on your existing coaxial
speakers MAY have different ohm ratings (coaxial are made up of two
different speakers, hence two different voice-coils), but combined they
present ONE resistance to your amplifier, this resistance is measured in
ohms. The lower the ohms, the lower the resistance. This means that a
speaker with a 4 ohm resistance will allow current to flow easier than a
speaker with a 10 ohm resistance, hence the 4 ohm speaker will be louder. A
direct short will, of course, have an ohm rating of 0. The point being, you
CAN NEVER have two different ohm ratings for a single speaker (they will
always combine to form ONE resistance). Perhaps your confusion stems from
the popularity of dual voice-coil subwoofers, these type of speakers DO
INDEED have two separate connections to each voice coil. However, in the
case of dual voice-coil subwoofers, the voice coils WILL ALWAYS be the same.

Chances are, the ohm rating of your existing speaker is 4 ohms, and I'M
POSITIVE the Jensen speakers have an ohm rating of 4 ohms (pretty much all
coaxials or triaxials made in the last 20 years have a resistance of 4
ohms).

It should be no problem just swapping out the speakers.

MOSFET

"Ken_B" > wrote in message
news:NqHgg.83196$IZ2.21294@dukeread07...
>I recently acquired a 1995 Gran Prix. The 6x9 rear speakers are very weak
>and I was thinking of replacing them with a nice pair of Jensens I have.
>
> But the Jensens only have one coil, whereas the ones in the car have two:
> 4-ohm and 10-ohm. I don't know the rating on the Jensens (model J310TX) -
> they are not marked and I can't find any specs on the Internet.
>
> Any advice?
>

[TalNLnky]

your wrong... DVC speakers don't ALWAYS have the same ohm load for each
voice coil... Pioneer made some OEM 6x9's that a while ago could be
found on partsexpress.com that were DVC with different ohm loads... i
wanna say 4 ohm & 12 ohm, but i may be wrong. Also, a lil company
called ascendant audio came out with a sub called the atlas (no longer
made) that had a 6ohm(or was it 2>) & 4ohm coil... regardless, the
reason for both speakers was to be able to mess with the Q of the
speaker by loading a resistor on one of the coils in something called
RDO which i believe stands for resitively dampened opperation.

point being, there is NO reason why a DVC speaker HAS to have the vc's
be the same ohm load... and this guy might be right.


--
TalNLnky

[MOSFET]

> point being, there is NO reason why a DVC speaker HAS to have the vc's
> be the same ohm load... and this guy might be right.
>
I wasn't saying that the voice coil ohm load in each of the speakers in a
coaxial (or triaxial) had to be the same ohm load, in fact, if you reread
what I said, I start by saying EXACTLY THIS. I was saying that when you
COMBINE those loads, you will get a single ohm load.

Now, I know that there ARE some coaxials that are bi-ampable, and therefore
it is possible that the ohm load would be different for each speaker that
makes up the coaxial, that makes sense. But I was not expecting that in a
stock speaker.

The point I am making is that it really doesn't matter what the SEPARATE ohm
loads are of a coaxial or triaxial speaker, it only matters what the
COMBINED ohm load is. UNLESS, of course, you are bi-amping them, which would
be VERY surprising to see in stock speakers.

MOSFET

[MOSFET]

, there is NO reason why a DVC speaker HAS to have the vc's
> be the same ohm load

READ THE SECOND SENTENCE OF MY FIRST POST.

MOSFET

[MOSFET]

Also, a lil company
> called ascendant audio came out with a sub called the atlas (no longer
> made) that had a 6ohm(or was it 2>) & 4ohm coil... regardless, the
> reason for both speakers was to be able to mess with the Q of the
> speaker by loading a resistor on one of the coils in something called
> RDO which i believe stands for resitively dampened opperation.

OK, this I did not know. So I do stand corrected. I did not know that
dual-voice coil subs could have different ohm loads on each coil. Hmmmm.
That's very interesting. You would THINK that this would create ALL SORTS
of anomalies and cancellation effects. But, of course, as subwoofers only
have to produce sound in a very limited audio bandwidth (20-80Hz),
apparently this is not a problem. Interesting.

Mosfet

MOSFET

[TalNLnky]

only one of the speakers i was talking about was a fullrange driver...
it in fact was NOT a bi or tri-axial speaker. The other speaker was a
sub.


how would having difference voice coils cause anomalies or
cancellations?
voice coils are just a tool of magnetic fields. by themselfs they do
not create any sound at all.... well... usually not... but thats a
whole different topic.

cancellation isn't an issue be cause the cone creates the sound... and
as long as you don't wire the vc's out of phase, there shouldn't be a
problem... even if you did... the lower ohm load coil most likely would
have more force behind it.

anomalies.... like what? its just ohm loads... try un-hooking a single
vc on a dvc sub... watch what happens... the T/S specs on the sub will
change, the way it reacts with the enclosure will change, and the
amount of power it recieves will change.... but it won't have anymore
distortion than before.


--
TalNLnky

[MOSFET]

> anomalies.... like what? its just ohm loads... try un-hooking a single
> vc on a dvc sub... watch what happens... the T/S specs on the sub will
> change, the way it reacts with the enclosure will change, and the
> amount of power it recieves will change.... but it won't have anymore
> distortion than before.

Well, OK, let's imagine we have a dual-voice coil subwoofer. One of the
coils is 4 ohms the other coil is 10 ohms. We take a 50 watt X 2 amplifier
and connect one channel to one of the voice coils and the other 50 watt
channel to the other voice coil. You are telling me that this will create
no problems with cancellation and other anomalies? You're kidding, right?
THIS WAS THE POINT I WAS MAKING.

I think the confusion we are having is that you keep assuming that the voice
coils will be combined (summed) to present a single load, however this IS
NOT that typical with dual voice-coil subwoofers (people use separate
channels to drive each voice-coil).
Look, I'm NOT talking about summing the voice coils, I am talking about
driving each of the coils with it's own amp. Won't this create TONS of
problems. BTW, this is what MANY PEOPLE DO who own dual-voice coil subs (in
fact, they will often connect one coil to one amp and another coil to
another amp).

Again, going back to the OP, it doesn't matter what the ohms of each of the
coils that make up the coaxial (or triaxial), it is the COMBINED ohm load
that matters.

I DO understand what you were saying about having different ohm ratings on
DVC subs and how this could be used to tweak the quality of the sound. But
don't those DVC HAVE to be summed before they can be hooked up to an
amplifier? Yes or no?

MOSFET

[MOSFET]

Again, using my previous example: If we had a two channel amp driving a DVC
sub where one channel of the amp drove one coil of the sub (let's say a 4
ohm coil) and the other channel drove the other coil (let's say a 10 ohm
coil), obviously the channel driving the 4 ohm coil will produce more
current than the other channel. How will this not screw things up? I would
expect a VERY peculiar frequency response curve.

Now I am no EE, but to me, that just seems like it would not work. But, of
course, COMBINED, there would be no problem.

MOSFET

[Ken_B]

Here's a picture..... http://www.cox-internet.com/kenb2002/speaker.jpg

"MOSFET" > wrote in message
...
> Again, using my previous example: If we had a two channel amp driving a
> DVC sub where one channel of the amp drove one coil of the sub (let's say
> a 4 ohm coil) and the other channel drove the other coil (let's say a 10
> ohm coil), obviously the channel driving the 4 ohm coil will produce more
> current than the other channel. How will this not screw things up? I
> would expect a VERY peculiar frequency response curve.
>
> Now I am no EE, but to me, that just seems like it would not work. But,
> of course, COMBINED, there would be no problem.
>
> MOSFET
>

[MOSFET]

Thank you for the picture, that is VERY helpful. Well, I do stand
corrected. It appears that your speaker IS bi-ampapable as it appears there
are TWO sets of wires coming from it. It APPEARS from the picture that this
is EXACTLY what is happening (the speaker is being bi-amped, in other words
it is receiving TWO channels of amplification, one for the 4 ohm woofer, one
for the 10 ohm tweeter). The capacitor present is obviously some type of
high-pass filter (for the tweeter I would guess) in the speaker. So my
guess would be that the tweeter is 10 ohms (and you connect that on the
right side based on your picture), and the woofer is 4 ohms and is connected
on the left side.

But let me make this clear, this DOES NOT appear to be a case of a dual
voice-coil. Although this coaxial DOES have two voice coils inside of it,
DVC means something very different. It means the voice coils are wrapped
TOGETHER on a single former, this is NOT the case here.

So the question is how do you connect all this to your new Jensen's? And
I'm not too proud to admit that this is a little out of my league (EVEN
AFTER all these posts of mine) as I've NEVER seen this type of set-up
before. Though I would think you could just connect the four-ohm side (the
left side) to your new Jensen's, I'm not sure what you would do with the
other speaker connection (the right side) IF IT IS TRULY BI-AMPED. I have
never heard of a stock stereo bi-amping a set of coaxials. Perhaps it is
not bi-amped but I just can't be sure so I am reticent to offer concrete
advice.

Perhaps someone who has seen this type of speaker before can offer better
advice.

Sorry.

MOSFET

"Ken_B" > wrote in message
news:x3Zgg.85138$IZ2.46176@dukeread07...
> Here's a picture..... http://www.cox-internet.com/kenb2002/speaker.jpg
>
> "MOSFET" > wrote in message
> ...
>> Again, using my previous example: If we had a two channel amp driving a
>> DVC sub where one channel of the amp drove one coil of the sub (let's say
>> a 4 ohm coil) and the other channel drove the other coil (let's say a 10
>> ohm coil), obviously the channel driving the 4 ohm coil will produce more
>> current than the other channel. How will this not screw things up? I
>> would expect a VERY peculiar frequency response curve.
>>
>> Now I am no EE, but to me, that just seems like it would not work. But,
>> of course, COMBINED, there would be no problem.
>>
>> MOSFET
>>
>
>

[MOSFET]

What I would do to start is to follow those two leads that come from that
6x9 and see if at some point they ARE connected. The more I think about it,
the more I would be VERY surprised to see stock 6x9's bi-amped. I SUSPECT
that at some point they come together (they split from two wires into four
wires). If this is the case, then you can simply connect this to your new
6x9's.

MOSFET

"MOSFET" > wrote in message
m...
> Thank you for the picture, that is VERY helpful. Well, I do stand
> corrected. It appears that your speaker IS bi-ampapable as it appears
> there are TWO sets of wires coming from it. It APPEARS from the picture
> that this is EXACTLY what is happening (the speaker is being bi-amped, in
> other words it is receiving TWO channels of amplification, one for the 4
> ohm woofer, one for the 10 ohm tweeter). The capacitor present is
> obviously some type of high-pass filter (for the tweeter I would guess) in
> the speaker. So my guess would be that the tweeter is 10 ohms (and you
> connect that on the right side based on your picture), and the woofer is 4
> ohms and is connected on the left side.
>
> But let me make this clear, this DOES NOT appear to be a case of a dual
> voice-coil. Although this coaxial DOES have two voice coils inside of it,
> DVC means something very different. It means the voice coils are wrapped
> TOGETHER on a single former, this is NOT the case here.
>
> So the question is how do you connect all this to your new Jensen's? And
> I'm not too proud to admit that this is a little out of my league (EVEN
> AFTER all these posts of mine) as I've NEVER seen this type of set-up
> before. Though I would think you could just connect the four-ohm side
> (the left side) to your new Jensen's, I'm not sure what you would do with
> the other speaker connection (the right side) IF IT IS TRULY BI-AMPED. I
> have never heard of a stock stereo bi-amping a set of coaxials. Perhaps
> it is not bi-amped but I just can't be sure so I am reticent to offer
> concrete advice.
>
> Perhaps someone who has seen this type of speaker before can offer better
> advice.
>
> Sorry.
>
> MOSFET
>
> "Ken_B" > wrote in message
> news:x3Zgg.85138$IZ2.46176@dukeread07...
>> Here's a picture..... http://www.cox-internet.com/kenb2002/speaker.jpg
>>
>> "MOSFET" > wrote in message
>> ...
>>> Again, using my previous example: If we had a two channel amp driving a
>>> DVC sub where one channel of the amp drove one coil of the sub (let's
>>> say a 4 ohm coil) and the other channel drove the other coil (let's say
>>> a 10 ohm coil), obviously the channel driving the 4 ohm coil will
>>> produce more current than the other channel. How will this not screw
>>> things up? I would expect a VERY peculiar frequency response curve.
>>>
>>> Now I am no EE, but to me, that just seems like it would not work. But,
>>> of course, COMBINED, there would be no problem.
>>>
>>> MOSFET
>>>
>>
>>
>
>

[TalNLnky]

MOSFET Wrote:
> Again, using my previous example: If we had a two channel amp driving a
> DVC
> sub where one channel of the amp drove one coil of the sub (let's say a
> 4
> ohm coil) and the other channel drove the other coil (let's say a 10
> ohm
> coil), obviously the channel driving the 4 ohm coil will produce more
> current than the other channel. How will this not screw things up? I
> would
> expect a VERY peculiar frequency response curve.
>
> Now I am no EE, but to me, that just seems like it would not work.
> But, of
> course, COMBINED, there would be no problem.
>
> MOSFET


as long as you don't exceed the thermal rating of either of the coils
it'll be perfectly fine. remember that both voice coils are actually
wrapped/wound together. They together make up one physical mass.
They are wound in parallel to each other at the same time, or on top of
each other. what causes the movement is just magnetic force.... by
having different amounts of force (amperage/voltage/wattage) going to
each coil all you do is change the TOTAL force driving/pushing the
moving mass (voice coil/former, spider, cone).

Now the only time this really ever becomes a concern, is if you wired
the vc's out of phase... they'd be acting against each other, thus
reducing the movement, but even then, they'd still move because one
coil would be gettin more power than the other. It'd basically just
reduce your thermal power handling and in turn also decrease efficiency
& spl.


--
TalNLnky

[MOSFET]

> as long as you don't exceed the thermal rating of either of the coils
> it'll be perfectly fine. remember that both voice coils are actually
> wrapped/wound together. They together make up one physical mass.
> They are wound in parallel to each other at the same time, or on top of
> each other. what causes the movement is just magnetic force.... by
> having different amounts of force (amperage/voltage/wattage) going to
> each coil all you do is change the TOTAL force driving/pushing the
> moving mass (voice coil/former, spider, cone).

I understand that dual voice coils are wrapped around each other and
therefore you get a combined resistance. My concern was when you use two
different amplifiers (or two different channels of the same amp) to drive
each coil. Are you saying that because the coils are wrapped around each
other, that each amp (in a dual amp scenario) will see the same resistance
(again, using our one coil at 4 ohms and the second coil at 10 ohms
example)? That doesn't seem logical to me, but I am no EE. It's how the
two different amplifiers (again, using my example) interact with one another
that would cause the problems and frequency anomalies. This was my point.
Again, it seems to me that the only way you can use a DVC sub that has two
different ohm ratings per coil is to wire the two coils together (either in
parallel or series) to produce ONE resistance and use a single amplification
channel to drive it.

Again, I could be wrong. Perhaps because the coils are wrapped around each
other they BOTH BECOME the same resistance even when connected to two
separate amplifiers. I don't know.

MOSFET

[Ken_B]

"MOSFET" > wrote in message
m...
>> as long as you don't exceed the thermal rating of either of the coils
>> it'll be perfectly fine. remember that both voice coils are actually
>> wrapped/wound together. They together make up one physical mass.
>> They are wound in parallel to each other at the same time, or on top of
>> each other. what causes the movement is just magnetic force.... by
>> having different amounts of force (amperage/voltage/wattage) going to
>> each coil all you do is change the TOTAL force driving/pushing the
>> moving mass (voice coil/former, spider, cone).
>
> I understand that dual voice coils are wrapped around each other and
> therefore you get a combined resistance. My concern was when you use two
> different amplifiers (or two different channels of the same amp) to drive
> each coil. Are you saying that because the coils are wrapped around each
> other, that each amp (in a dual amp scenario) will see the same resistance
> (again, using our one coil at 4 ohms and the second coil at 10 ohms
> example)? That doesn't seem logical to me, but I am no EE. It's how the
> two different amplifiers (again, using my example) interact with one
> another that would cause the problems and frequency anomalies. This was
> my point. Again, it seems to me that the only way you can use a DVC sub
> that has two different ohm ratings per coil is to wire the two coils
> together (either in parallel or series) to produce ONE resistance and use
> a single amplification channel to drive it.
>
> Again, I could be wrong. Perhaps because the coils are wrapped around
> each other they BOTH BECOME the same resistance even when connected to two
> separate amplifiers. I don't know.
>
> MOSFET
>

I have a shop manual for this car (two volumes, each about 2-inches thick!)
and the color codes indicate the 10-ohm connections as "Audio Input" and the
4-ohm connections as "Subwoofer Control". Also, each wire connects
separately to the radio amp.

The thing is, both speakers do work, but they are very low in volume
compared to the front speakers.

I'm thinking I need to visit a junk yard, after all. Thanks for all the
responses.