Help - Speaker Hookup

[Logthumper]

OK you electronic wiz kids. Help. I would like to install a 1/8"� stereo jack so I can connect a small JBL amplified stereo speaker pack (made for use with the I-Pod) to the left and right front speaker radio outputs. The in dash Jensen radio has speaker outputs (+ & -) for each of the left and right front speakers and for each of the rear speakers.

A 1/8"� stereo jack has three connection points, a common and left and right connection. Is it possible to wire the radios front speaker outputs (right & left) to this plug?

The jack can be wired so that inserting a 1/8"� plug will either turn off the standard speakers or simply connect along with them. The JBL amplified speaker pack sits very nicely between the dash and steering column and provides outstanding sound (with volume control) without drowning out whats going on around you..

Here is what I'm trying to do. My hearing is normal but my wife can hear a whisper a mile away. She does not like anything loud. When I listen to music, I like to hear it like it was played. So while driving down the road, if she's reading or in back resting, I like to crank up the radio. This arangement would keep most of the sound on my side.

Any and all "how to"� advice is appreciated.

Thought I would ask before I blew something up

[Logthumper]

OK you electronic wiz kids. Help. I would like to install a 1/8"� stereo jack so I can connect a small JBL amplified stereo speaker pack (made for use with the I-Pod) to the left and right front speaker radio outputs. The in dash Jensen radio has speaker outputs (+ & -) for each of the left and right front speakers and for each of the rear speakers.

A 1/8"� stereo jack has three connection points, a common and left and right connection. Is it possible to wire the radios front speaker outputs (right & left) to this plug?

The jack can be wired so that inserting a 1/8"� plug will either turn off the standard speakers or simply connect along with them. The JBL amplified speaker pack sits very nicely between the dash and steering column and provides outstanding sound (with volume control) without drowning out whats going on around you..

Here is what I'm trying to do. My hearing is normal but my wife can hear a whisper a mile away. She does not like anything loud. When I listen to music, I like to hear it like it was played. So while driving down the road, if she's reading or in back resting, I like to crank up the radio. This arangement would keep most of the sound on my side.

Any and all "how to"� advice is appreciated.

Thought I would ask before I blew something up

[John_Canfield]

The issue might be a mismatch in impedance; the radio amplifier output is 8 ohms or whatever and the JBL input impedance is ?? The JBL might be looking for a high or low impedance input - can't say. With a gross mismatch in impedance you might have a little distortion and certainly won't have an efficient coupling. There are low Z to high Z matching transformers that would mitigate the problem.

Having said that, I would just hook them up and see what happens. Don't think anything bad would happen to either component. If it sounds okay to you, then you're good to go

[MrTransistor]

Hi Logthumper,
If the speaker outputs are labeled ˜+' & ˜-' that usually means that they are bi-polar and should never be connected ˜-' to ˜-' or ˜+' to ˜+'. This can blow fuses real quick when the outputs of the amplifiers are push / pull. This is by no means a hard and fast rule though. With outputs labeled ˜+' and ˜ground', or something similar, the grounds can be connected together and would be appropriate to use in your application. This type of amplifier uses a capacitor in series with the output that keeps the signal symmetrical about ground. Of course, the grounds would be common and connect to the common of the pin jack and the ˜+' of the left and right speakers would connect to the left and right inputs of the JBL amplified stereo speaker pack pin jack.

The ˜+' & ˜-' setup can be checked by using a volt meter set on about ˜20 Volts AC' scale. Measure the voltage on the ˜+' and ˜-' leads to ˜chassis ground' with a speaker connected and the volume at a comfortable level. If you read some voltage on the ˜+' and no voltage on the ˜-', then it's a good bet that the ˜-' is ground referenced. If the voltage reading on the ˜+' and the ˜-' are about the same, then the output is bi-polar and the ˜-'s should not be connected together. Remember that any reading is going to bounce around with the music your playing at the time and can be as low as a few MiliVolts for soft passages to 10 to 20 Volts for ear splitting outputs depending on the speaker impedance and the type of output amplifier.

Bear in mind that connecting speaker outputs (10 to 20 Volts) to ˜AUX' inputs (generally 1 VRMS max.) is a bit of over-kill. You'll need to turn the volume way down on the Jensen to keep from overdriving the input of the JBL. A better way for sure is if the Jensen has ˜AUX' outputs on the back. These can easily be wired to the pin jack and would be the correct impedance and amplitude.

I apologize if this is too deep. It's difficult for this old electronics instructor to explain in lay terms. If in doubt, try a good audio shop, they can reference the Jensen schematics and give you a definitive answer.

[MrTransistor]

Hi Logthumper,
P.S. Dony's suggestion comes from her sister who is a professional musician. Sound filtering ear protection like musicians wear while performing. There are several different kinds available with different levels of sound reduction and these would be great for any noisy environment your wife finds herself in. Dony is researching this for herself.

[aux_man]

Mr. Thumper -

The speaker level outputs on your RV stereo are not compatible with the "mini" stereo plug on your powered speakers. What you need to do is get a speaker/line level converter to take your Jensen speaker level down to a line level that you JBL speakers can accept. Before you get your cutters and electrical tape out, go to radio shack and ask for this device. It should cost you around $20. You will also want to pick up a mini stereo jack with RCA "Y" pigtail to allow for a "tool free" connection. If radio shack does not have this, any car stereo or custom AV shop will have one.

God Bless our Troops!

[Logthumper]

Thanks to all for the info/help. End result was very simple and works well. I ended up tapping into the output speaker leads from the radio with two small cube speakers. While I was at it I relocated the TV/Radio switch down to the dash next to the radio (where it belongs). Now with the switch in the "TV" position the radio is only heard from the two added Personal Speakers. In the "Radio" position, the overhead speakers are active along with the two added speakers. When the Television is on, the radio is turned off. Pic of added speakers is below.
Fun project, but at 30 degrees oputside???
Thanks again.