Bavsound Subs on Individual Audio

[PS2N54]

from reading, it seems like Bavsound stopped supporting their subwoofers on Individual Audio packages due to some issues specificity on the Individual audio package cars. and for some people it seems like it wasnt an issue and was straight plug&play.

just wondering if anyone who has experience with this issue and can describe what the scenario was. Or if anyone has technical knowledge on cause of failure.

i would like to use the V1 ghost subs on a 09 car with individual audio, i dont mind making any modifications to have them run reliable.

[Throatpunch]

It has to do with the ohm resistance on the speaker which should match the amp. A lower ohm speaker on an amp not designed for it can damage the amp by overheating

[PS2N54]

i havent pulled out the OEM individual audio sub to verify yet, but from what i read so far, the oem subs are 8ohms.

the bavsound ghost v1 subs are also 8ohms... still not getting what issue is that people had with these units, unless the bavsound subs are advertised as 8ohms but are actually less? if this is the case, i was thinking to match the amp's impedance/resistance via inline resistor and heatsink, then even if the bavsound sub is less than advertised 8ohms, it wouldnt burn the amp as the in-line resistor is taking all the heat from correcting resistance.

the wattage supported by sub should have no adverse affects on amp or rest of speakers, if sub is rated for less wattage than what amps give it, the sub will just blow, if its rated for higher wattage you get less performance out of it.

will do this swap + inline resistor correction over the winter and report back unless someone else posts here that already tried this and still had failure which would confuse me even more as to route cause of issue.

[Freiheit]

Originally Posted by nzero

i havent pulled out the OEM individual audio sub to verify yet, but from what i read so far, the oem subs are 8ohms.

the bavsound ghost v1 subs are also 8ohms... still not getting what issue is that people had with these units, unless the bavsound subs are advertised as 8ohms but are actually less?

I don't know your electrical background, so if this is kid stuff for you then forgive me.

The ohm number you see on the box for the BavSound woofer, just like the ohm reading you get from the BMW woofer with your multimeter, is a 'nominal' number - its the resistance of the speaker when its at rest and not loading an amplifier.

Your meter measures resistance but the value in question is impedance, a reactive load. That means that as the frequencies handed to the speaker increase or decrease, the load on the amp changes. You might have a driver reading 8ohms "at rest", but run a 200Hz tone through it and the number goes up. Then when you send a 2000Hz tone through it the number goes down. And there will be peaks and valleys to the impedance all along the frequency plot. Its not as pronounced with a single driver as it is with a passively-crossed multi-driver array (aka "loudspeaker") but it still happens with every driver, and at some point in the plot the amp might see the speaker as a short. Infinity used to make a home speaker called the Kappa 9 that would drop to almost a dead short under certain loads, but they were still "8 ohm" speakers.

If you want a metaphor then consider your suspension - you can get the same static (nominal) ride height out of a whole bunch of different combinations of springs and shocks, but they act differently under load. The woofers, and all speakers for that matter, work with amplifiers in a similar fashion.

Originally Posted by nzero

if this is the case, i was thinking to match the amp's impedance/resistance via inline resistor and heatsink, then even if the bavsound sub is less than advertised 8ohms, it wouldnt burn the amp as the in-line resistor is taking all the heat from correcting resistance.

Don't. It looks like it would work on paper but I wouldn't do it. A standard resistor has a flat or at least more linear resistance therefore the impedance curve of the driver might suffer. Yes, resistors are used in passive crossovers but thats as part of a well-designed network along with caps and chokes, and its all supposed to work together.
Another thing to consider: you might add a couple of ohms to shore up the lower parts of the impedance curve, but what are you doing to the stuff thats at 8ohms? Now its at 10ohms. Is it supposed to run at that load?

Originally Posted by nzero

the wattage supported by sub should have no adverse affects on amp or rest of speakers, if sub is rated for less wattage than what amps give it, the sub will just blow, if its rated for higher wattage you get less performance out of it.

Thats not quite true. First, many ratings are really "ratings" and don't hold water. Vendors are known for either underrating various parts so they can sneak into different competition classes, or else overrating them so people buy their garbage.
Second, audio philosophy is that its easier to blow "50 watt" speakers with a 50 watt amp that produces distortion, than it is to blow a 50 watt speaker with a 100watt amp that makes clean power. I have "100watt" speakers hooked to a 350wpc amp here, they don't blow because I don't crank them up past "plenty loud". A friend of mine hooks hifi headphones to his 200wpc amp, no issues.

As far as performance goes, the power rating has zero to do with it. The first metric to look at is what that speaker does when its provided a signal based on 1 watt of power; this is the sensitivity number. The standard is measured at a distance of 1 meter away from the driver surface (technically, I can't remember if its measured from a straight edge across the surround, the edge of the driver, or the edge of the voice coil, sorry), and its given in a weighted dB average. Typical hifi speakers are anywhere from 87dB to 100dB efficient, but there are a few outside that range at either end. Normal speaking tones are around 60dB, so a speaker with 87dB efficiency could easily drown out normal conversation with music played on 1 watt of amp power. A speaker with 100dB efficiency (think Klipschorns) could sound like a live jam with 1 watt.

Originally Posted by nzero

will do this swap + inline resistor correction over the winter and report back unless someone else posts here that already tried this and still had failure which would confuse me even more as to route cause of issue.

If I had to guess whats happening... BavSound came out with the Ghost drivers about 10 years ago when these cars were new. No problems then. Now there are people reporting problems. Same drivers but on 10 year old amps. Factory amps were built to offer the best performance with the cheapest possible components, and to not blow up if the rest of the system is left alone. I think that the components inside the amps are aging, most likely the capacitors but it could be anything. The characteristics of the amp change with that age.

If I can't talk you out of this then get a 1-2 ohm (max) part with the highest watt rating for that resistor. Many of the 10-12W parts usually have their own heat sinks embedded. Depending on the output of the amp that still might not be enough protection. You may consider going to a couple of 4 ohm 12W resistors in parallel to each other netting you 2 ohms (or a pair of 2ohm resistors netting you 1ohm), then mounted that pair in series with the woofer. And I still wouldn't do it. I'd service the amp first.

Don't be surprised if you hurt something else, most likely the sound if not the electronics themselves.

[Mtrizzyy]

I think it's because of the faulty amp of the IA, I had ran through 2 sets of oem subs on my 2012 that kept blowing after weeks of use and then I had 2 bav sound sound subs that were warranted and then that failed again so they gave me a full refund I didn't know what was going on, given the fact that I had also blown subs on my previous e92 m3 that was a 2011 I thought it would be a faulty amp that was made in those two years so I decided to call bmw here in Toronto and they wanted 3300cad and I wasn't even sure that was the isssue, I checked ecs tunning and found that they had one brand new on sale for half the cost and I got my 3rd set of bav sound subs and took a gamble since other shops couldn't point me in the right direction and since then no issues after I had installed the new amp and I didn't have to code it !!!!! I got the new updated amp part number 65128054808

Here are the previous revisions so it might make sense why only some people are affected is my best guess:

Previous Revisions
65-12-7-846-908, 65 12 7 846 908, 65.12.7.846.908, 65127846908
65-12-7-847-666, 65 12 7 847 666, 65.12.7.847.666, 65127847666
65-12-7-850-091, 65 12 7 850 091, 65.12.7.850.091, 65127850091
65-12-7-851-364, 65 12 7 851 364, 65.12.7.851.364, 65127851364

[PS2N54]

Originally Posted by Freiheit

I'd service the amp first.

thanks so much, makes a lot of sense. going to do amp first then!

[Freiheit]

Originally Posted by nzero

thanks so much, makes a lot of sense. going to do amp first then!

You're welcome.

If you take your amp to a tech, I would suggest asking if the amp is either clipping, or putting out significant DC voltage to the outputs. Either one can destroy speakers. The DC at the outputs could be an imbalance in the differential pair (assuming the EPS amp is a conventional solid-state Class AB amp with a negative feedback circuit). Clipping can be quite a few different causes but off the top of my head I could say too high of a voltage at the amp inputs, or a weak power supply in the amp (there's that age thing again, as the filter capacitors lose their moxie).