My Volvo Speaker says 4 ohm, why does everyone say 8 ohm?

[Ozark Lee]

This comes up from time to time and the upshot is that it really doesn't matter. Back in the early days solid state amplifiers (early 70s) the speaker impedance, which is a nominal measurement that varies widely with frequency, was rather important. The early output transistors were Class B (Push-Pull configured) and they were very picky about the load. Too big of a mismatch would blow the output transistors and those transistors were quite expensive and they were typically sold in matched pairs.

Any audio amplifier from the mid '80s onward no longer uses the bulky output transistors and they have become much more tolerant of a wide range of load impedances.

Volvo had some real issues with speakers largely due to their insistence on using crappy adhesives and foam. I guess they are supposed to be more environmentally friendly but that doesn't really matter when you have to replace them after they disintegrate and/or the magnet falls off.

I have changed out all of the speakers on every Volvo I have ever owned and on almost all of them I have used Infinity 4 Ohm speakers. They sound fine, better than the originals did when they were new, and I can crank them full blast with no ill effects. Some of the cars have the additional amplifiers and some are driven directly from the head unit. In both cases, the 4 Ohm versions work just fine even when they are paralleled like from the factory where the dash tweeters and the front doors run in parallel and the rear doors and rear deck run in parallel giving a nominal impedance of 2 Ohms.

Of all of the speaker specifications to consider when buying replacement speakers the impedance is pretty much at the bottom of the list.

...Lee

[mrbrian200]

...the 4 Ohm versions work just fine even when they are paralleled like from the factory where the dash tweeters and the front doors run in parallel and the rear doors and rear deck run in parallel giving a nominal impedance of 2 Ohms.

Of all of the speaker specifications to consider when buying replacement speakers the impedance is pretty much at the bottom of the list.

...Lee

I would disagree, even with modern amp designs it's still risky on an OE setup that probably wasn't designed to drive a 2 ohm load.

At the least you're going to get more line losses and current limiting through the amp and the wiring resulting in compressed dynamics. Obvious distortion may not occur when the supply voltage is dropping in relation to current draw before hard clipping occurs and/or the relatively small gauge wires to the speakers effectively starts limiting current when driving a lower impedance load. The waveforms get 'scrunched' but not with the abrupt 'chopped off flat line' of hard clipping that is more obvious to the ear.

[abscate]

I can't believe how much is spent on high audio performance....in a car.

[mrbrian200]

I can't believe how much is spent on high audio performance....in a car.

For some of us it's where we primarily listen to music. For those who are more picky, it's also one of the more difficult environments to achieve genuine high fidelity/audiophile sound. In the vehicle environment various constraints result in a process of which trade-offs you can live with and which you can't. Less so in a home environment: assuming an unlimited budget at worst you have some pesky standing waves affected to room size/shape, speaker, or seating positions, most of which you can change. In a vehicle environment most of these variables are fixed.

[Clemens]

You could always do it like in police academy and rip the front seats out...

But I agree, to get a really nice audio experience you need alot of knowledge and money. For most of us an upgrade of the 20 or so year old factory speakers is an improvement. Knowing that the right impedsnce speakers would be the best choice, i seriously can't find any 8 ohm speakers in 5 1/4 inch. So there is no real option to go 4 ohm, is there?

[bill d cat]

Lee (thank you!) wrote up the "S70 speakers demystified" DIY viewtopic.php?f=33&t=57976 and used 4 Ohmx 6 1/2 inch speakers in the rear doors so I'll consider this evidence that the change works.

The factory PN 3533622 rear door speakers are NLA from Volvo so the alternatives would include used speakers from eBay that are just about as old.

The 4 Ohm x 6 1/2 inch Kenwood speakers are less than $30 for a pair (shipped and taxed) and they must be better than the 21 year old speakers that are in the doors now.

(I've not spent anything on speakers in the 21 years that I've had the car.)

[mrbrian200]

i seriously can't find any 8 ohm speakers in 5 1/4 inch. So there is no real option to go 4 ohm, is there?

Yes upgrades get 'difficult' when OEs start wiring higher impedance speakers in parallel. Excepting some subwoofer applications, aftermarket stuff is designed almost solely around 4 ohm drivers intended to be wired 1 speaker per channel. Your better options are to either use the 4 ohm speaker and delete/disconnect the second set that is wired in parallel or add a separate power amp fed from the line-out on the back of the HU (if it has that) to drive them independently.

[Clemens]

I´ve got the premium sound with the extenal amp, so I could just delete the rear d pillar tweeters or live with a slightly lower impedance that i´d get from adding 4 ohm door speakers and leaving the d pillars in.

The nice thing about the premium sound equipped 850s is that the dash and front toor speakers are 4 ohm each, because the dash is powered through the head unit, the doors through the amp (as per volvo´s wiring diagram and as from checking out what I have in my dash).

[bill d cat]

On the V70:

The 2 dash tweeters (3533623) are labeled 8 Ohm

The 2 front door speakers (3533621 and 3533620) are 4 Ohm

The 2 rear door speakers (3533622) are 8 Ohm

The 2 rear D pillar speakers (9128772 and 9128773) are 8 Ohm

It seems to me that using 4 Ohm replacement speakers for the rear doors would be more correct than what Volvo did. I'd think I 'd want the same resistance on all 4 channels. (Or did I completely botch the math?)

Signed,

Confused

[Clemens]

No, you don´t necessarily need the same resistance because you can alter the loudness with the fader settings of the HU. The front door speakers would be the "loudest" in this setup.