Crutchfield Advice?

[Sub_Lover]

The guy at Crutchfield suggested that a DVC sub driver driven with a 2
channel amp (one channel to each VC) would be better sounding then the
same driver is a SVC version. Does this make sense? He said that the
DVC sub would be more responsive? I also read where it's not a good
idea to run a seperate channel to each VC. However isn't that one of
the reasons for the DVC?

[Scott Gardner]

On 7 Mar 2005 21:33:20 -0800, "Sub_Lover" > wrote:

>The guy at Crutchfield suggested that a DVC sub driver driven with a 2
>channel amp (one channel to each VC) would be better sounding then the
>same driver is a SVC version. Does this make sense? He said that the
>DVC sub would be more responsive? I also read where it's not a good
>idea to run a seperate channel to each VC. However isn't that one of
>the reasons for the DVC?

Crutchfield has excellent customer service, and they're fairly
knowledgable about the products they carry, as long as you limit your
questions to topics that are discussed in the owner's manuals.

That being said, I don't think they have very many engineers answering
the phones in the customer service department, so I'd take any
techinical or theoretical advice they give you with a grain of salt.

As long as the overall impedence that the sub presents to the
amplifier is within the amp's limits, I don't think you'll notice a
difference in sound quality between:

1) an amp bridged mono powering a DVC sub that's had the voice coils
bridged

2) a two-channel amp with each channel powering one voice coil, or

3) an amp bridged mono powering a SVC sub.


--
Scott Gardner

"God is a comedian playing to an audience too afraid to laugh." (Voltaire)

[MOSFET]

"Sub_Lover" > wrote in message
ups.com...
> The guy at Crutchfield suggested that a DVC sub driver driven with a 2
> channel amp (one channel to each VC) would be better sounding then the
> same driver is a SVC version. Does this make sense? He said that the
> DVC sub would be more responsive? I also read where it's not a good
> idea to run a seperate channel to each VC. However isn't that one of
> the reasons for the DVC?
>
We have all been conditioned to believe that dual anything is better than a
single of anything (dual exhaust, etc.). With voice coils, this is simply
not the case. Dual voice coil subs do not have twice the quantity of voice
coils as single coil subs. The two coils are wound on top of one another so
there is no length advantage, either. The ONLY advantage I can see with DVC
subs is that you have more wiring options. DVC subs allow you to wire each
coil either in series or parellel with your amp and/or other DVC subs. This
gives you the ability to wire your subs in such a way as to optimize the
impedence your amp "sees".

As far as hooking the left channel to one coil and the right channel to
another, this is not typically done (this was the subject of a recent
thread, here). Though the coils will NOT potentially fight one another as
some have thought, there IS a potential for some cancellation (one coil
recieving a signal 180 degrees out of phase from the other, thereby
cancelling the signal), and for this reason I would not recommend it.

MOSFET

[Cyrus]

In article >,
"MOSFET" > wrote:

> "Sub_Lover" > wrote in message
> ups.com...
> > The guy at Crutchfield suggested that a DVC sub driver driven with a 2
> > channel amp (one channel to each VC) would be better sounding then the
> > same driver is a SVC version. Does this make sense? He said that the
> > DVC sub would be more responsive? I also read where it's not a good
> > idea to run a seperate channel to each VC. However isn't that one of
> > the reasons for the DVC?
> >
> We have all been conditioned to believe that dual anything is better than a
> single of anything (dual exhaust, etc.). With voice coils, this is simply
> not the case. Dual voice coil subs do not have twice the quantity of voice
> coils as single coil subs. The two coils are wound on top of one another so
> there is no length advantage, either. The ONLY advantage I can see with DVC
> subs is that you have more wiring options. DVC subs allow you to wire each
> coil either in series or parellel with your amp and/or other DVC subs. This
> gives you the ability to wire your subs in such a way as to optimize the
> impedence your amp "sees".
>
> As far as hooking the left channel to one coil and the right channel to
> another, this is not typically done (this was the subject of a recent
> thread, here). Though the coils will NOT potentially fight one another as
> some have thought, there IS a potential for some cancellation (one coil
> recieving a signal 180 degrees out of phase from the other, thereby
> cancelling the signal), and for this reason I would not recommend it.
>
> MOSFET
>
>

And even that last part is arguable, but I'm far too lazy for that hehe.
Its more of opinion and personal experiences/tastes etc etc.

I must concur with the first part though, more of anything and pretty
colors/lights seem to equal sales.

--
Cyrus

*coughcasaucedoprodigynetcough*

[Sub_Lover]

I guess my choices are to sell the DVC and buy the SVC: or I could sum
the output of the sub from the deck using a y connector and then split
the mono signal with another y connector. This would allow me to send
the same mono signal to each VC. This would give me 90 watts per VC or
180 watts. The sub has a high efficiency so I could do this. My amp
would see a 4ohm load and run cooler then a 2 ohm load and according to
MTX the distortion levels and noise would be lower.

[MZ]

> As far as hooking the left channel to one coil and the right channel to
> another, this is not typically done (this was the subject of a recent
> thread, here). Though the coils will NOT potentially fight one another as
> some have thought, there IS a potential for some cancellation (one coil
> recieving a signal 180 degrees out of phase from the other, thereby
> cancelling the signal), and for this reason I would not recommend it.

Yeah, but if both amp channels are being driven by the same preamp signal
(left and left, for example) then there's no cancellation. In short, it
makes no difference. Don't sell your DVC to get a SVC.

[Sub_Lover]

So, I think, you're saying to just use one side of the sub outputs and
then a Y-Connector to the amp and hookup a each channel, of the amp, to
each VC? I'll see how this sounds and if there is amp power then there
is no reason to get the SVC. The only advantage is that I could run my
amp bridged for double the power. But that may be overkill.

Subwoofer signals are suppose to be mono but I've heard were they are
not. This makes no sense since 99% of music listeners have one
subwoofer so what would be the point of mixing the sub signal into
stereo.

[MOSFET]

"Sub_Lover" > wrote in message
ups.com...
> So, I think, you're saying to just use one side of the sub outputs and
> then a Y-Connector to the amp and hookup a each channel, of the amp, to
> each VC?

Yes, you could do it this way, but what I do is sum (add together) the left
and right signal of the sub output and THEN run that into the amp. As you
said, some bass is in stereo so this way you would not lose anything. Yes,
as I pointed out in my previous post, there is the potential for
cancellation but this is minimal. Also, the key is that any canellation
that may occur does so BEFORE the signal gets to the amplifier. But, again
this is very small (I never notice any in my system).

MOSFET

[BrianQ]

"Sub_Lover" > wrote in news:1110260000.085798.31810
@o13g2000cwo.googlegroups.com:

> The guy at Crutchfield suggested that a DVC sub driver driven with a
2
> channel amp (one channel to each VC) would be better sounding then the
> same driver is a SVC version. Does this make sense? He said that the
> DVC sub would be more responsive? I also read where it's not a good
> idea to run a seperate channel to each VC. However isn't that one of
> the reasons for the DVC?
>

One thing this discussion is missing so far is getting
the most out of your amp for least amount of $$

Most 2ch amps on the market today give their highest continuous power
when run in 4 ohm mono. For example, an amp rated at 75X2 RMS into 4
ohms is often rated at 300x1 RMS into 4 ohms. A 4 ohm SVC woofer and a
relatively cheap amp can produce some good quality sound.

I guess you could argue that you could achieve the same thing by running
a 2 ohm stereo capable amp into a dual 2ohm woofer. In fact,in many
cases this would theoretically draw the exact same amount of power from
the same amplifier run in 4 ohms mono, but for some reason, at least in
the lower cost amps, distortion seems to creep in earlier when run in
the 2 ohm stereo setup.

[MOSFET]

"BrianQ" > wrote in message
0...
In fact,in many
> cases this would theoretically draw the exact same amount of power from
> the same amplifier run in 4 ohms mono, but for some reason, at least in
> the lower cost amps, distortion seems to creep in earlier when run in
> the 2 ohm stereo setup.

How can this be? When you run 4 ohm mono YOU ARE running it in 2 ohm stereo
mode, just summed (stereo is not exactly the right word, two channel is more
correct). 2 ohms + 2 ohms = 4 ohms. How could anything dealing with power
be any different? Doesn't the speaker "see" EXACTLY the same thing?

MOSFET

MOSFET

[MZ]

> One thing this discussion is missing so far is getting
> the most out of your amp for least amount of $$
>
> Most 2ch amps on the market today give their highest continuous power
> when run in 4 ohm mono. For example, an amp rated at 75X2 RMS into 4
> ohms is often rated at 300x1 RMS into 4 ohms. A 4 ohm SVC woofer and a
> relatively cheap amp can produce some good quality sound.
>
> I guess you could argue that you could achieve the same thing by running
> a 2 ohm stereo capable amp into a dual 2ohm woofer. In fact,in many
> cases this would theoretically draw the exact same amount of power from
> the same amplifier run in 4 ohms mono, but for some reason, at least in
> the lower cost amps, distortion seems to creep in earlier when run in
> the 2 ohm stereo setup.
>

Nah, that's not the case. you can run 4 ohms bridged or two ohms stereo
without any inherent benefit in either case - distortion or otherwise.

[MZ]

> How can this be? When you run 4 ohm mono YOU ARE running it in 2 ohm stereo
> mode, just summed (stereo is not exactly the right word, two channel is more
> correct). 2 ohms + 2 ohms = 4 ohms. How could anything dealing with power
> be any different? Doesn't the speaker "see" EXACTLY the same thing?

You are correct, MOSFET. The two are (almost) the same. In the vast
majority of amplifiers out there, the power output will be identical in
both cases. Technically, distortion will increase with the 4 ohm mono
setup because you introduce crossover distortion and asymmetrical
clipping. But these effects are inaudible in every amp I know of.

[BrianQ]

MZ > wrote in -
ip.org:

> I guess you could argue that you could achieve the same thing by
running
>> a 2 ohm stereo capable amp into a dual 2ohm woofer. In fact,in many
>> cases this would theoretically draw the exact same amount of power
from
>> the same amplifier run in 4 ohms mono, but for some reason, at least
in
>> the lower cost amps, distortion seems to creep in earlier when run in
>> the 2 ohm stereo setup.
>>
>
> Nah, that's not the case. you can run 4 ohms bridged or two ohms
stereo
> without any inherent benefit in either case - distortion or otherwise.
>

I acknowledged that technically, at least, both configs should produce
the same power.

My comments about a difference are based only on general personal
impressions/experience. Over the years I seem to have had alot more
"comebacks" from amps cutting out when driven hard in 2 ohm stereo, and
likewise seem to find the overall SQ to be lacking.

Perhaps the deficit occurs on the sales floor when budget driven
customers insist on buying a smaller 2 ch amp merely because
it is "2 ohm stable", and that when the customer follows my
recommendation, he ends up with an adequate sized 2ch amp running in
mono to his woofers. A self-fulfilling prophecy?

[Sub_Lover]

It's amazing to me the different advice I'm getting. I actually called
Infiity today and spoke with a tech. He told me that if I ran the
Infinity Sub 12.1D ( DVC) with my MTX amp I could blow the driver. He
said that my amp is underpowered. He said, that 90watts per VC is
dangerous because the sub, when pushed hard, would not have enough
juice. He is telling me to buy the SVC version 12.1 and then bridge my
amp so I would have 360 watts total power available from my amp. This
seems like an awful lot of juice for a driver that is suppose to have a
96db rating. My other sub, a 12" Titanic 1200, has an efficiency
rating of 89db and is a SVC. I'm using the same MTX 502 Thunder in
bridge mode and I have to turn down the gain because it's over powering
my door speakers. If the efficiency ratings were ture then the
Infinity sub should need about the 1/3 the power of my Dayton Titanic
to reach the same SPL. Go figure. I'm a little bit confused.

[MZ]

> It's amazing to me the different advice I'm getting. I actually called
> Infiity today and spoke with a tech. He told me that if I ran the
> Infinity Sub 12.1D ( DVC) with my MTX amp I could blow the driver. He
> said that my amp is underpowered.

You could do a search on "underpowering" and what engineers have to say
about this notion. Please keep in mind that the "tech" you spoke to is a
minimum wage phone answerer with no background in electronics.


> He said, that 90watts per VC is
> dangerous because the sub, when pushed hard, would not have enough
> juice. He is telling me to buy the SVC version 12.1 and then bridge my
> amp so I would have 360 watts total power available from my amp. This
> seems like an awful lot of juice for a driver that is suppose to have a
> 96db rating. My other sub, a 12" Titanic 1200, has an efficiency
> rating of 89db and is a SVC. I'm using the same MTX 502 Thunder in
> bridge mode and I have to turn down the gain because it's over powering
> my door speakers. If the efficiency ratings were ture then the
> Infinity sub should need about the 1/3 the power of my Dayton Titanic
> to reach the same SPL. Go figure. I'm a little bit confused.

I think I've already demonstrated to you why the sensitivity ratings of this
driver are not accurate when compared to other drivers.