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Dash speaker removal
https://slantsix.org/forum/viewtopic.php?t=30968		 Page 1 of 1
Author:  busboy [ Sun Sep 07, 2008 10:26 pm ]
Post subject:  Dash speaker removal
I would like to replace the dash speaker in my 72 Swinger. I had a quick look up there yesterday, looks like two nuts to remove on either end, but there are some screws sticking down through the plate. How do I get at the screw heads, or do I need to? Anybody done this?
Author:  emsvitil [ Mon Sep 08, 2008 12:24 am ]
Post subject: 
If it's like my 64, the plate is held on with 2 nuts.

The speaker is attached to the plate, so to get the speaker out you remove the plate.

Here is where I replaced the stock 8 ohm 6x9 speaker with 2 4 ohm 4x6 speakers.

http://groups.msn.com/EdSvitilsSportste ... ments.msnw

There's a member here that makes adaptor plates.
Author:  busboy [ Mon Sep 08, 2008 10:51 am ]
Post subject: 
Thanks Ed, that doesn't sound too hard. My speaker is a 4x10. I don't know what ohms the stock ones were, but I picked up a "dual voice" 8 ohm one to replace it. I did a search on here and someone said not to use an 8 ohm speaker with my factory radio (AM) cause it can wreck it. I want to use the new speaker for now cause I'm planning an audio upgrade down the road. I am really not an electrical tech guy, do you know how this could wreck the radio?
Author:  emsvitil [ Mon Sep 08, 2008 2:07 pm ]
Post subject: 
Quote:
Thanks Ed, that doesn't sound too hard. My speaker is a 4x10. I don't know what ohms the stock ones were, but I picked up a "dual voice" 8 ohm one to replace it. I did a search on here and someone said not to use an 8 ohm speaker with my factory radio (AM) cause it can wreck it. I want to use the new speaker for now cause I'm planning an audio upgrade down the road. I am really not an electrical tech guy, do you know how this could wreck the radio?
I think that would be to not use a 4 ohm.....

It's safe to use more resistance (the output volume just drops a little).

If you don't have enough resistance, you can hurt the radio.......
Author:  moparfreak77 [ Mon Sep 08, 2008 7:23 pm ]
Post subject: 
I bought this speaker plate from a member on FABO. It worked good. Let me know if you want to know his name.
Image
Author:  busboy [ Tue Sep 09, 2008 5:03 am ]
Post subject: 
So if I understand this right, if the factory speaker is 4 ohm then it's ok to put in an 8 ohm, I just can' go less ohms....yes?
Author:  lindross [ Tue Sep 09, 2008 6:04 am ]
Post subject: 
Quote:
So if I understand this right, if the factory speaker is 4 ohm then it's ok to put in an 8 ohm, I just can' go less ohms....yes?
That is correct. An 8 ohm speaker will be less load on your radio than a 4 ohm would be.
Author:  KBB_of_TMC [ Tue Sep 09, 2008 10:17 am ]
Post subject: 
While I couldn't find the speaker's specified resistance in my '71 service manual, my Sams photobook schematics for several '71 Mopars all show 8 ohm speakers. The 8 ohm number is rather nominal; if you measure an 8 ohm speaker with a DMM you might well see 6.5 ohms or so. An old beat-up speaker could easily have a few shorted turns too.

I recently bought a pair of 4x10" 8 ohm speakers for a '68 Fury from J.C.Whitney, but then found that their tweeter dome sticks up above the plane of the mounting flange around 1/4" - so I'd need fabricate some kind of spacer to mount it.

While the other components are still available, the output impedance matching transformer used in those factory radios is very difficult to find, so I'd avoid any damage to it.
Author:  '74 Sport [ Tue Sep 09, 2008 11:04 am ]
Post subject: 
Quote:
...so I'd need fabricate some kind of spacer to mount it...
Look no further than your shop and a spare length of rubber fuel line. Cut short pieces to the required length, slip them over the mounting studs, and install the speaker bracket. The rubber spacers provide the additional clearance, as well as a bit of cushion to prevent buzzing from vibration.

Works great,
Jerry
(The guy that makes the aforementioned speaker brackets) :wink:
Author:  busboy [ Fri Sep 12, 2008 7:20 pm ]
Post subject: 
Well, I just checked the box for the new speaker, turns out it's 4 ohm. I may not be able to use this thing :shock:. I don't have the old speaker out yet. Did anyone come up with an ohm rating on the stock speaker ??
Author:  R. Wood [ Fri Sep 19, 2008 1:01 pm ]
Post subject: 
Do you have an ohmmeter? If you do you could measure the impedance of the stock speaker that you remove. It probably won't read exactly 4 or 8, but if it reads over 4 it's a safe bet that it is rated 8 ohms.

I have the AM/FM radio in my '75 and had the same question, but my 4x10 was blown so I could not measure it. To be safe I am running a pair of 4 ohm speakers in series, creating an 8 ohm load. The radio has been very happy with this setup, and I've been using it this way for around 3 years.

If you wanted to do this with your system, you have a few options. You could run a second 4 ohm speaker in series, as I did, or you could wire a dummy 4 ohm resistor in series to raise the impedance that the amp sees. Or find a 4x10 speaker rated 8 ohms :shock:


R. Wood
Author:  busboy [ Tue Sep 30, 2008 7:56 pm ]
Post subject: 
I got the speaker out, it wasn't too bad. Had to drop the radio, disconnect a couple of duct hoses and the passenger defrost vent. I see what you're talking about the frame of the speaker. The mounting holes on my new one are about a 1/2" short on each end, I think I can make up some extension brackets that will work. The stampings on the original speaker are 2496874, AAOV, DELUXE, and 433132 (or 488132). Anyone know what the ohm rating of the original speaker may be?
Author:  emsvitil [ Tue Sep 30, 2008 8:33 pm ]
Post subject: 
Most likely 8 ohms.

8 ohms would be safe to use even if it was 4 ohms.

4 ohms isn't save to use if it was 8.............


So either an 8 ohm speaker or two 4 ohm speakers in series....
Author:  busboy [ Fri Oct 03, 2008 7:12 pm ]
Post subject: 
Here's where I'm at. I hooked the "dual voice" boxes in series and the speaker tested at 7.5 ohms. That should keep me out of trouble. This speaker is advertised as a direct replacement (4x10) for the factory unit. The factory unit is 11 3/8", mounting hole to mounting hole. This unit is 10 3/8", so I fabbed up some extensions. It will fit in and work just fine till I finish with the complete stereo upgrade. Thanks for your help.
Author:  steponmebbbboom [ Sun Oct 26, 2008 4:13 pm ]
Post subject: 
Impedance and resistance are not one and the same, you cannot measure impedance with a multimeter. Impedance is the resistance a speaker offers while it is under load. the pulsating DC current creates eddys that cut across the voice coils and change the resistance to current flow.

if you have an 8 ohm dual voice coil speaker, you have the option of wiring the voice coils in parallel for 8 ohms of impedance, or wiring them in series for 4. but why would you buy a dual voice coil speaker for a single-channel radio?

did you also consider the wattage rating of your speaker versus the rms power output of your radio? if you didnt, you will not be happy with the sound pressure level.
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