(n)A-GAME Posted March 28, 2009 Report Share Posted March 28, 2009 I picked up some C70 parcel shelf speakers (8 ohm impedance) and was hoping to fit them in my S70, which has the 4 ohm stock units in the rear deck. Why do it? Mostly because I know the Dynaudio compnents will put the paper cones to shame, and the price was right. Putting aside the mounting difficulties and fabricating a new bracket to make them fit for a second, will I run into electrical issues? If it matters, here is the setup:4x40W 850R Amp (OEM)Sc-901 HUC70 Dynaudio Dash TweetersC70 center speaker in the dashAlpine Type-S 5.25" Front Door Speakers (4 ohm impedance)OEM rear door speakers Link to comment Share on other sites More sharing options...
HeavyIron Posted March 28, 2009 Report Share Posted March 28, 2009 I picked up some C70 parcel shelf speakers (8 ohm impedance) and was hoping to fit them in my S70, which has the 4 ohm stock units in the rear deck. Why do it? Mostly because I know the Dynaudio compnents will put the paper cones to shame, and the price was right. Putting aside the mounting difficulties and fabricating a new bracket to make them fit for a second, will I run into electrical issues? If it matters, here is the setup:4x40W 850R Amp (OEM)Sc-901 HUC70 Dynaudio Dash TweetersC70 center speaker in the dashAlpine Type-S 5.25" Front Door Speakers (4 ohm impedance)OEM rear door speakersDan,The factory 8" speakers in an S70 are 8ohm along with the rear door speakers. Reason is, they are bridged off the rear two channels resulting in a 4ohm load to the amp. Before I wnet stereo crazy, my car originally came with a sc-816 and 4x50amp. Question to you is; how come you are running 5.25" front door speakers when stock is 6.75"? Mounting is not that difficult. Biggest pain is that S70 parcel mount speakers are top loading which means you have to strip off the D pillar plastic and your parcel shelf cover, seat belts, blah...blah..blah. Link to comment Share on other sites More sharing options...
(n)A-GAME Posted March 28, 2009 Author Report Share Posted March 28, 2009 Yeah I meant 6.5" for the front door speakers-we retrofitted them into the oem speaker housing. Getting back there wasn't too tough actually, I left the seatbelts in-i was messing around anyways back there to set up my diversity antenna. And I think I confused the c70 and s70 impedances too - the new ones are 4 ohms. That's what I meant to put in. The stereo bug has bitten lol Link to comment Share on other sites More sharing options...
jschaefer7406 Posted March 28, 2009 Report Share Posted March 28, 2009 Yeah I meant 6.5" for the front door speakers-we retrofitted them into the oem speaker housing. Getting back there wasn't too tough actually, I left the seatbelts in-i was messing around anyways back there to set up my diversity antenna. And I think I confused the c70 and s70 impedances too - the new ones are 4 ohms. That's what I meant to put in. The stereo bug has bitten lolHello,As you may already know, that will cause a problem. Going from 4Ω to 8Ω as originally stated would be okay, but going from 8Ω to 4Ω will overload the amp. You can either add a 4Ω resistor in series with the new deck speakers to make them 8Ω, or disconnect the rear door speakers so it is 4Ω overall. If you run the 4Ω and 8Ω speakers in parallel as originally designed, you'll end up with only a 2.67Ω load at the amp. Good luck to you,Joe Link to comment Share on other sites More sharing options...
(n)A-GAME Posted March 28, 2009 Author Report Share Posted March 28, 2009 That's exactly what I needed to know. Guess I'm off to pick up some resistors. Thanks! Link to comment Share on other sites More sharing options...
mkc70 Posted March 28, 2009 Report Share Posted March 28, 2009 Hello,As you may already know, that will cause a problem. Going from 4Ω to 8Ω as originally stated would be okay, but going from 8Ω to 4Ω will overload the amp. You can either add a 4Ω resistor in series with the new deck speakers to make them 8Ω, or disconnect the rear door speakers so it is 4Ω overall. If you run the 4Ω and 8Ω speakers in parallel as originally designed, you'll end up with only a 2.67Ω load at the amp. Good luck to you,JoeOn paper that may look like what needs to be done, but just because you add a resistor in line with the speaker to get to the same nominal impedance does not make it right. Just don't go to 2 ohms unless you have the larger Volvo amplifier, 4 should be no problem for your current amp. Link to comment Share on other sites More sharing options...
turbomoose Posted March 28, 2009 Report Share Posted March 28, 2009 When you get these resistors could you please take pics, and if you could please provide the info on where to find them. I have some Vifa 4Ω speakers in my rear doors, with a resistor I was told would do the job, but I don't think it's the correct resistor. Thanks! Link to comment Share on other sites More sharing options...
jschaefer7406 Posted March 28, 2009 Report Share Posted March 28, 2009 On paper that may look like what needs to be done, but just because you add a resistor in line with the speaker to get to the same nominal impedance does not make it right. Just don't go to 2 ohms unless you have the larger Volvo amplifier, 4 should be no problem for your current amp.Hello,Not to argue, but how does that "not make it right"? If he wants to run a 4Ω driver and an 8Ω driver in parallel, it's the only way to do it and not overload the amplifier. Any other ideas?Joe Link to comment Share on other sites More sharing options...
turbomoose Posted March 28, 2009 Report Share Posted March 28, 2009 Yeah, on paper, and in the real world 4+4=8. Get an ohm meter and check it out. Link to comment Share on other sites More sharing options...
mkc70 Posted March 28, 2009 Report Share Posted March 28, 2009 Hello,Not to argue, but how does that "not make it right"? If he wants to run a 4Ω driver and an 8Ω driver in parallel, it's the only way to do it and not overload the amplifier. Any other ideas?JoeNp, to clarify "not make it right", you have set in your mind that the system MUST see a 8 ohm nominal impedance to play is what I have read so far. Unless you have drawn out your system and calculated each component on the amplifier you are just guessing at the impedance. Does (n)A-GAME have any factory crossovers in his setup? Just because a speaker says it is 4 ohms does not mean it will meter the same. Take a multimeter to some of your speakers and you will typically see that they measure less than what their rating. The impedance is constantly changing depending on how the speaker is moving, so what I was getting at is that just change the speaker and be done with it. It is not a dramatic enough change for this situation to really make a difference. Yeah, on paper, and in the real world 4+4=8. Get an ohm meter and check it out.So if I wired a 4ohm tweeter with a 4ohm subwoofer in series it would relate to a 8ohm total impedance? Would it make a difference if the tweeter was first or second in wiring to the amplifier? Would this setup even work? Link to comment Share on other sites More sharing options...
turbomoose Posted March 29, 2009 Report Share Posted March 29, 2009 So if I wired a 4ohm tweeter with a 4ohm subwoofer in series it would relate to a 8ohm total impedance? Would it make a difference if the tweeter was first or second in wiring to the amplifier? Would this setup even work?No, No, and it would "work" in terms of producing sound, but not equal 8. Link to comment Share on other sites More sharing options...
HeavyIron Posted March 29, 2009 Report Share Posted March 29, 2009 No, No, and it would "work" in terms of producing sound, but not equal 8.It would equal 4. Speakers wired in series do not change the ohm load to the amp. Speakrs wired in parallel efectively half the ohm load for each additional speaker added. I.E. 3-8ohm speakers in parallel = a 2ohm load Link to comment Share on other sites More sharing options...
turbomoose Posted March 29, 2009 Report Share Posted March 29, 2009 ^^^ Exactly. Link to comment Share on other sites More sharing options...
turbomoose Posted March 29, 2009 Report Share Posted March 29, 2009 Series Vs. Parallel Wiring.This is what I used when I replaced my rear door speakers. Link to comment Share on other sites More sharing options...
BEJinFBK Posted March 29, 2009 Report Share Posted March 29, 2009 Resistors? I disagree. Bad Plan. This is not a good idea...We're talking about AC impedences here. NOT DC.4 "speaker nominal ohms" + 4 "fixed resistive" ohms are apples and oranges.A standard electrical meter measures resistance in ohms at DC only. That's why the ratings are always stated as NOMINAL impedences. It varies.Speaker impedence varies constantly over the frequency range of audio.Hanging a fixed resistance in series with a speaker on an amp output is atotally half assed way to "match " impedences. And a big waste of power.( Not to mention that they would have to be huge to last and would get really, possibly skin burning, dangerously hot when ya crank it way up.)It's also going to effect phasing and frequency response, and that means bad sound.The only time that I've ever seen resistors used as actual loading components in audio is on the repair bench. Even then, only for very short testing periods.Either wire your shelf and door speakers in series instead of parallel ( which will reduce your effective audio output ) or just disconnect the doors.Even better. Go with the right impedences to begin with. Just because you have some speakers doesn't mean they're the right ones for your current system.I don't mean to be a downer here, but resistors are a way, way, waaaay low budget kludge here.BTW, Great wiring link here! Series Vs. Parallel Wiring.This guy may get a little heavy with the math for some,but he's right on the money with his info. Before you even start to consider this, DO SOME RESEARCH! Hit the net, read up on systems,stop by some high end shops and ask a few long time audio guys that do this stuff for a living.Don't be in a hurry...You'll get there! ;) Link to comment Share on other sites More sharing options...
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