Using line out?

[cafla...@cox.net]

I plugged a mono plug into the line out on my Brennan B2 and with the speakers wired in to the speakers outputs and connected and playing i plugged the plug into the line out and the left speaker stopped playing.  Right played.  I had the sense off so the speakers could play with the line out port working.  

Does not seem to be much signal out as my large sub did nothing.  Separate issue maybe.

Do i need a stereo line out plug?  Or is there a particular length to the plug pin?

Amp played the medium sized Klipsch book shelves fairly loud if turned up to 50 or so.

Obviously not a giant amp but it worked well.  

Need to find out how to use the line out correctly and maybe how to boost the signal if thats what the Boston acoustics pv800 needs?

[Daniel Taylor]

The line output, when used as analog, is intended for a stereo plug.  The B2's amp is not intended to handle the left.right pair wired together in mono.  I don't know if a mono plug would connect left and right together, but I'd be leary of trying it.

If the B2's amp does not have enough power for you, you can connect the line output via a stereo connector to and external amp.

[cafla...@cox.net]

Speakers are in a stereo pair.  Will get a stereo line out plug.  Thanks.  My sub has a mono rca input.  

[PMB]

Hi cashflash...,

The Line Out socket on the B2 is stereo so you need a stereo (TRS) jack plug.

Plugging a mono plug in is effectively shorting one channel to ground, hence no sound.

I couldn't find a decent photo of the rear panel of the Boston but from I've seen you'll need someway of combining the stereo output from the B2's Line Out to mono for the PV800 - you cannot simply join the two signals together.....

Paul

Brennan Support.

[Davywhizz]

Do you just want to use the line out to feed a powered sub? That seemed to be your intention in your other recent post.

As Paul says, you need to to combine the stereo B2 line output to become a mono sub input. And also convert  stereo minijack to a mono RCA plug (or socket, then use a sub cable, which tend to be thicker and more insulated than standard RCA, but otherwise the same).

My NAD D3020 v2 amp uses a stereo minijack as its subwoofer output and the amp is sold with an adaptor: a stereo plug on one end and a mono RCA socket on the other, with a short length of cable in between. Other than that, I've never seen a stereo jack to mono RCA connector up close, though you can find them on-line. You may get a NAD dealer to sell you just the adaptor? 

The B2 line out will carry the full frequency range, of course, it's not a dedicated sub output. That shouldn't matter if your sub has a crossover control to filter out the higher frequencies. I find it best to set them initially about 10Hz above whatever is the lowest frequency rating for the main speakers. If I can't find that I start at 80Hz. 

[Daniel Taylor]

From what I've read about the design of the B2's output stage, it's a very bad idea to short the two channels together with a cable.  Someone else can explain it better than I remember.  Anyway, don't do it.  Your sub should have a stereo input, then the two channels can be dealt with inside the sub in whatever way that manufacturere how chosen.

[Davywhizz]

Is this what you are thinking of Daniel?

"The power amplifier is a bridge amplifier - red and black outputs are both driven - so you cannot connect the two black terminals together and you cannot use the loudspeaker outputs as an input to another amplifier."

I was assuming the B2 line out  is different in that it's a stereo jack socket, thus has three connections not four. Paul's reply did seem to suggest it may be possible to combine the left and right signals (the ground connection is shared in all the stereo jacks I've seen to date). 

[Daniel Taylor]

Yes, that's what I was thinking of.  Thanks Davy.  And what you say about the line output does make sense.  So I guess the advice about not connecting the two channels together is only true for the speaker outputs.  Thanks.

[Davywhizz]

Hopefully, but it may not be quite that simple. Paul seemed to suggest it's possible, but didn't say how (not that he necessarily should). 

My NAD stereo minijack to single RCA socket adapter works perfectly as a subwoofer feed, but I have no idea how it's wired inside.

I seem to remember that summing signals together sometimes needs resistors to stop each signal trying to go back down the other cable.

Hopefully someone who knows more than me will be along soon.

[cafla...@cox.net]

My Boston acoustics pv1000,sub mentions that if you have a “lazy” sub from low sub  output power from the source you can use both left and right channel inputs into it versus its mono input.  Noticeable louder.  So I have a stereo plug into the line out on the Brennan B2 and stereo rca plugs onto the sub.  Works.

That being said the klipsch speakers run ok if I turn the Brennan up quite a bit.  

Their specs say 90db sensitivity.  My old Boston acoustics micro metal case are 98db.  

If my understanding is correct the BA’s should play louder with less amp volume needed.  Hopefully I got this right.

I rain I need a small DAC? To boost the line outs signal strength?

More sensitive speakers and a boost for the line out should have us going well in using the Brennan as a small stereo amp for our motorhome sound system.

The Brennan played the Klipsch speakers very loud at full volume then shut off.  

5 minute or more the amp reset itself.

Stressed but worked well.

Hooked up a large amp and they drove the Klipsch speakers very well.  More that we need for a motorhome.

Anyone have a link to a good DAC or whatever I need to boost the signal to the sub so I do not have to turn its volume up so high?

Thanks in advance for anyone’s help…

[PMB]

Hi All,

I don't have access to the schematics for the B2 but suspect that the Line Out is upstream from the power amplifiers and joining L and R there will also affect the amplifiers outputs.

Most Sub Woofers, in my experience have stereo inputs and combine these actively, rather than just joining the channels together. It sounds like the PV1000 have stereo inputs.

Caflashbob - if you use a DAC between the B2 and the PV1000 sub, the B2's volume control does not work - the optical out is at a fixed level. You need a (stereo) preamplifier to boost the signal level if the output from the B2 is not sufficient to drive the PV1000.

Paul

Brennan Support.