Stereo/Bridge switch while bridging MS2125

DDS · Post by **DDS** » Thu Sep 10, 2009 8:23 am

Hi guys.

I shold like to find out something about my original MS2125.
Can I use my MS in a bridged mode for subwoofer with the STEREO/BRDG switch set to STEREO? I should like to do it in order for my system to play the bass notes, recorded in both channels.
Do I understand it correctly? The bridged mode is turning on by a proper connection of acoustic cable, and not by changing the STEREO/BRDG switch. And the switch is only for choosing, whether the amp is playing signal from the left channel [BRDG] or from both channels [STEREO].
So, connecting subwoofer, can I use my MS in a bridged mode with the switch set to stereo, in order for the subwoofer to play bass from both channels?

Post by **kg1961** » Thu Sep 10, 2009 8:41 am

Think the switch only changes if the both rca are going to be used or just one
here is the manual
http://download.phoenixphorum.com/Manua ... ms2125.pdf

scottn29 · Post by **scottn29** » Thu Sep 10, 2009 9:02 am

if the amp is bridged to mono it will only play mono, no stereo

DDS · Post by **DDS** » Thu Sep 10, 2009 9:11 am

scottn29 wrote:if the amp is bridged to mono it will only play mono, no stereo

I realize it is impossible for one sub to play stereo.
I want my sub, connected to the amp in a bridged mode, to play the summary signal from both inputs. Will it happen if I bridge the amp with ST/BR switch set to STEREO position?

scottn29 · Post by **scottn29** » Thu Sep 10, 2009 10:12 am

most bass is recorded in mono anyways, I dont know about the amp setting

nico boom · Post by **nico boom** » Thu Sep 10, 2009 11:06 am

Dmitry! nice to hear from our RUSSIAN MEMBER again!!

You need a dual voice-coil subwoofer to get the effect you want.
With the amp in normal stereo-mode, using left AND right inputs, a dual voice-coil subwoofer will play both left and right input-material together.
What you want is not possible with a single-voicecoil sub as far as I know.
Expect a Email about further news!

Post by **stipud** » Thu Sep 10, 2009 11:33 am

nico boom wrote:Dmitry! nice to hear from our RUSSIAN MEMBER again!!
You need a dual voice-coil subwoofer to get the effect you want.
With the amp in normal stereo-mode, using left AND right inputs, a dual voice-coil subwoofer will play both left and right input-material together.
What you want is not possible with a single-voicecoil sub as far as I know.
Expect a Email about further news!

In that case if a note was playing on the one side, and not on the other, you would only energize one of the voicecoils. The Thiele-Small parameters would be thrown out the window in this case, and it would affect the sound. I do not recommend running different power to the separate voicecoils; they should be the same at all times.

I am not sure if the amplifier will do summed mono for you in Stereo mode... Hopefully it does, but I can't find any confirmation.

See if your headunit has the feature. If not, you can get an adaptor RCA, or make one yourself:
http://download.phoenixphorum.com/TechSupport/cmono.pdf

The only problem with this case is you will get a ~6dB loss on your signal, due to the resistors. This means you will need to run your gains a bit higher to offset the difference.

nico boom · Post by **nico boom** » Thu Sep 10, 2009 12:03 pm

The adaptor rca is a good idea, plug it into the left channel input of the amp, set the switch to bridge, use left channel out for + and right for - and you're set.

I do not agree fully with you Tom about using those two coils for exact the same signal only.
You think those two coils are only for matching the impedance?
In home-setups it's not unusual to find stereo signals going to one single subwoofer [with only one unit inside, double voicecoil].

Post by **stipud** » Thu Sep 10, 2009 1:17 pm

http://mobile.jlaudio.com/support_pages.php?page_id=163

Essentially, if there is any difference between the signals driving each coil at any given point in time at a given frequency, the voice coils will either fight each other or help each other, depending on the phase relationship of the two signals at that frequency. This is not the same thing as bridging an amplifier and can create undesirable non-linearities and distortion because different input signals at each voice coil create shifts in the speakers electrical parameters.

For this reason, it is advisable to mono-bridge the amplifier whenever possible and connect the voice coils of the dual voice coil speaker together in parallel or series. If a dual voice coil subwoofer must be wired to two independent channels, the inputs to both channels should ideally be the same (summed mono) and every effort should be made to match the gains of both channels as closely as possible.

A dual voice coil speaker will behave exactly the same way whether it is wired with its coils in series or parallel. The only thing that changes is the impedance that the amplifier sees. This means that enclosure calculations are constant for dual voice coil woofers no matter how the coils are connected to each other, as long as both are connected.

A common misconception with regard to dual voice coil speakers is the assumption that nothing changes if you power only one of the voice coils. With only one coil hooked up, a dual voice coil speaker will suffer a loss in reference efficiency of about 3dB (only half the coil windings are being energized) as well as a significant shift in its Thiele/Small parameters. This renders any enclosure calculations inaccurate unless you remeasure the speakers parameters with only one coil hooked up. Failure to account for the different parameters of a dual voice coil speaker with only one coil powered can result in very poor performance.

Now don't get me wrong... I have done this in the past with no ill effects, but the ideal way is defintiely to get a summed mono signal in the first place. I dont think DDS is the kind of guy who would take even the smallest risk of affecting the sound negatively.

DDS · Post by **DDS** » Thu Sep 10, 2009 5:22 pm

Thank you, guys, for your detailed answers.

Nico, my sub has a single voice-coil, it is AudioArt RW12 for now..

RCA-adaptor is a good idea. Suppose you mean something like this.. http://download.phoenixphorum.com/TechSupport/cmono.pdf
But, I would prefer for the amp to sum signals from both inputs; suppose it would be the best way. So I will have to test it somehow.
What if I use the record with low frequency signal recorded in left and right channels by turns. I will check out, does the signal play both times. If there will be the silence whily testing for some time, it will mean the MS does not sum signals. And if there will be bass for all the time, then my MS does it!
Suppose this way I could define, wether my MS sums the signals for the bridging mode in stereo.
Now all that I need is some record like this...

Post by **stipud** » Thu Sep 10, 2009 10:19 pm

Isn't it as simple as unplugging the left RCA?

DDS · Post by **DDS** » Fri Sep 11, 2009 1:28 am

stipud wrote:Isn't it as simple as unplugging the left RCA?

I was trying to find different complex solutions, but there was so simple answer.

This is very great and simple idea! Thank you!

Stereo/Bridge switch while bridging MS2125

Stereo/Bridge switch while bridging MS2125

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