Can (should) I place a speaker parallel to a high level (speaker output) to line level converter?

[Bruce]

I am considering amplifying VHF radio output some of the time. The VHF radio has a mono 4.5 watt @ 4 ohm output that is currently powering a Poly-Planar MB21 speaker.

What would happen if I installed a PAC SNI-35 Variable LOC Line Out Converter in parallel to the existing speaker? I am uncertain how having a converter (transformer) in parallel to the speaker would change the resistance of the load.

@David Analog, @Mainah can you guys help?

Thanks

 

[Mainah]

I am considering amplifying VHF radio output some of the time. The VHF radio has a mono 4.5 watt @ 4 ohm output that is currently powering a Poly-Planar MB21 speaker.

What would happen if I installed a PAC SNI-35 Variable LOC Line Out Converter in parallel to the existing speaker? I am uncertain how having a converter (transformer) in parallel to the speaker would change the resistance of the load.

@David Analog, @Mainah can you guys help?

Thanks

I am not familiar with line out converters or using amps with line level ins. My guess is that the converter will place a load and will affect resistance to some degree.

 

[FloJet]

I'm not understanding what you are trying to do? That PAC is for Headunits that no not have any RCA cable out puts. So to use the HU with the amp, must covert speaker level outputs to rca outputs. So I am little confused by what you mean by paralleling the existing speaker?

 

[mark_m]

I think he's trying to get from speaker line level back to rca format so he can run into his existing audio setup. Could you put some kind of switch in the mix to toggle small speaker vs thru amp?

 

[Bruce]

@FloJet, I am piping speaker level VHF output to one channel of an amplifier. I have an existing external speaker and a single output from the VHF radio. My intention is to wire a speaker level to low level converter in parallel to the external speaker. I can not find any resistance ratings for speaker level to RCA converters so I am unsure what that will do to the resistance of the circuit.

 

[FloJet]

I think he's trying to get from speaker line level back to rca format so he can run into his existing audio setup. Could you put some kind of switch in the mix to toggle small speaker vs thru amp?

If thats the case, than what he is doing right now is probably his best option unless he wants to replace the unit to something with RCA outputs. You can line drive each individual speakers but I don't think that's what he is looking for here.

 

[FloJet]

Gotcha. If there is any resistance, it should be at minimal if even that.

 

[David Analog]

A little (or a lot of) speculation here on my part. The SNI internal coupling transformers would apply to the output side. To satisfy the source unit output circuit there might first be a lower input resistance. Check with PAC to get this number or measure the input resistance across the PAC SNI input + & -., assuming there is no capacitor coupling across the input, and I doubt there is.
So let's estimate the PAC SNI-35 to have a 20-ohm input resistance. Tied in parallel with an 8-ohm speaker gives you a 5.71-ohm load. Okay if the VHF radio output is rated @ 4-ohms (unlikely), and NOT okay if rated @ 8-ohms.
If the SNI input was 100-ohms then tied in parallel with 8-ohms would be a 7.41-ohm load, which wouldn't be an issue.
Probably best to switch between the speaker input positive and the SNI-35 input positive.
I'm guessing that the VHF speaker output ground is common to its chassis, thus will not require switching along with the positive.