[peppepp]

Hello, this is my first post here. I am planning to upgrade my base system audio this coming weekend by adding a DSP amplifier, as I currently don't have a stock amp. I have already upgraded my mid-range speakers and added tweeters, which was a significant improvement over the stock layout that lacked tweeters.

However, now I want to take it to the next level. My question is about the tweeters - I have heard that they are very sensitive and can break if they receive the wrong frequencies. As I will no longer need the crossovers in the doors after adding the DSP amp, I plan to disconnect them. What should I keep in mind during this process? Should I change the amplifier's crossover settings before connecting the speakers to prevent the risk of blowing the tweeters? Or should I simply avoid turning on the stereo while the crossover settings are not set?

Cheers!

[Billfitz]

Tweeters should always be protected from turn on transients and user error with a series capacitor. It should be sized as a first order filter with the knee frequency half that of the crossover frequency.

There is no crossover in the doors, unless you added one. The stock arrangement is just a capacitor of the ten cent variety.

The crossover settings should be input before sending any signal to the amp.

[peppepp]

Originally Posted by Billfitz

Tweeters should always be protected from turn on transients and user error with a series capacitor. It should be sized as a first order filter with the knee frequency half that of the crossover frequency.

There is no crossover in the doors, unless you added one. The stock arrangement is just a capacitor of the ten cent variety.

The crossover settings should be input before sending any signal to the amp.

Yes I have added crossovers.

So basically, I should set the correct crossover settings for the amp before disconnecting the tweeters from the current crossovers and before connecting them to the amp?

[Billfitz]

It doesn't matter, just so long as you don't play anything through the system before setting the crossovers. The protection caps must be installed before anything else, without them you could blow the tweeters just by powering up the amp.

[peppepp]

Originally Posted by Billfitz

It doesn't matter, just so long as you don't play anything through the system before setting the crossovers. The protection caps must be installed before anything else, without them you could blow the tweeters just by powering up the amp.

Im pretty sure I had them installed when I added tweeters earlier. If it's these. 2:58 in the video.

[peppepp]

I just understood a bit more now after a little research. I currently have two different types of crossovers in each door. One between the mids and tweeters. And one between the subs and mids. Thats why I was confused. I did the tweeter install 2 years ago, so completely forgot the layout of it.

[Billfitz]

The passives still have to go, you don't want to use passives and actives. Then you need to do as I posted with respect to protection caps, sized as first order high pass filters an octave lower than the active crossover frequency, so they don't affect response.

[peppepp]

Originally Posted by Billfitz

The passives still have to go, you don't want to use passives and actives. Then you need to do as I posted with respect to protection caps, sized as first order high pass filters an octave lower than the active crossover frequency, so they don't affect response.

Sorry I dont have much experience in this area really so I dont fully understand the terms you are using. So if I have understood correctly, I should replace the crossover/capacitor seen in the video to only a capacitor? Then run the highpass filter through the DSP?

[Billfitz]

Yes. Use this to calculate the required value, using only the high pass calculation. If your crossover is 4kHz, for instance, you'd calculate a 2kHz high pass. With 4 ohm drivers you get 20uF.

https://www.diyaudioandvideo.com/Cal...akerCrossover/

Do not use a non-polarized electrolytic cap, they're junk. Use a poly cap, like this:

https://www.parts-express.com/Jantze...939?quantity=1

[peppepp]

Originally Posted by Billfitz

Yes. Use this to calculate the required value, using only the high pass calculation. If your crossover is 4kHz, for instance, you'd calculate a 2kHz high pass. With 4 ohm drivers you get 20uF.

https://www.diyaudioandvideo.com/Cal...akerCrossover/

Do not use a non-polarized electrolytic cap, they're junk. Use a poly cap, like this:

https://www.parts-express.com/Jantze...939?quantity=1

Okay thanks for the help!

[peppepp]

So I'm right now trying to figure out how all wires are supposed to be connected, but I cant figure out how I'm supposed to connect the input wires. The red/black cables as seen on the cable bundle are the input wires. And the right of the two white squared inputs in the amp is the input. With the amp i got the cable part as seen in the middle of the picture with all different types of wires. This is what makes me confused since I don't know where the input wires goes. Anyone know how I'm supposed to connect them? (for some reason the picture flips over, sorry for that)

[peppepp]

I have pulled all the wires and connected them to the amp, but I won't receive any input signal. I measured the voltage from the input cables, but there is none when I turn on the stereo and therefore not letting the amp turn on. Any ideas?

[Billfitz]

I'm guessing here but did you connect the HU line level outs to the amp? Or the HU speaker outs? The speaker outs would have a signal, but I don't think the line level outs will unless you code the HU to Hi-Fi.

[peppepp]

Originally Posted by Billfitz

I'm guessing here but did you connect the HU line level outs to the amp? Or the HU speaker outs? The speaker outs would have a signal, but I don't think the line level outs will unless you code the HU to Hi-Fi.

Yes should be the HU line level outs to the amp. I connected a plug n play cablekit (Eton bak) in between the subs and mids under the seats. Sub/midrange into their correct outputs in the amp, and the input cables into the input for high-level input.

Page 4 is a manual of how its supposed to be wired. https://cloud.gsbildeler.no/api/part...ikt%20base.pdf

[esaru]

Originally Posted by Billfitz

I'm guessing here but did you connect the HU line level outs to the amp? Or the HU speaker outs? The speaker outs would have a signal, but I don't think the line level outs will unless you code the HU to Hi-Fi.

Hijacking this thread, my post count is too low for dms.

I am currently on a quest to improve the horrible sound of my X3 f25 with the measly eu base stereo. I’ve found your posts an essential part of my beginners introduction to bmw audio retrofitting, so thank you for providing this in depth knowledge to the masses.

I’ve seen the general recommendation of the proven earthquake sws subwoofers. Being based in Sweden, those are proving difficult (and expensive) to obtain.

I’ve been browsing for reasonable alternatives that are more locally available and would appreciate some input.

How would these hold up to the earthquakes? I’m somewhat hopeful since they are not shy to provide a full table of specifications.

DLS CRPP-BMW1.82

https://dls.se/product/cruise-crpp-b...=frlnvz4x7saf7

https://dls.se/product/cruise-crpp-bmw1-82/

Feel free to answer by private message or in this hijacked thread. Sorry for the poor forum etiquette.

[Billfitz]

It has specs close to that of the OEM Hi-fi woofers, albeit with 2 ohm impedance. They don't show xmax, so there's no way of knowing how loud they can go. I wouldn't call them an upgrade to OEM. They're not in the same league as Earthquakes, but they would be better than the base 6.5 inch.

[esaru]

Originally Posted by Billfitz

It has specs close to that of the OEM Hi-fi woofers, albeit with 2 ohm impedance. They don't show xmax, so there's no way of knowing how loud they can go. I wouldn't call them an upgrade to OEM. They're not in the same league as Earthquakes, but they would be better than the base 6.5 inch.

As suspected, the Earthquakes remains uncontested.

I’ve had an interesting development! Found a pair of second hand Earthquake 8x for 50 euros. Sadly they are not the 8xi 2 ohm model.

I have the match 8dsp incoming which delivers 160w @ 2 ohms or 90w @ 4 ohms.

Could I wire my pair of 8x in parallel in order to achieve the desired 160w 2 ohm?

If so, how would it be done in practice? The amp has 2 subwoofer channels with respective + and -, which gives me 4 cables to manipulate. Could it be done cleanly close to the amp in order to just run one set of cables to each speaker?

Or do I need to run cables between the speakers? I am wary of this since I wouldn’t know how to get cables across the raised center console.

Does this classify as bridging the amp, and are there potential complications/incompatabilities?

Just to be clear on the differences between 8x and 8xi. Is the only difference (with my amp) that 8xi gets more power and therefore the potential to play louder? Their characteristics beyond power/volume are exactly the same?

I am obviously very uninformed in this area but looking to make the most of my situation. Grateful for any advice!

[Billfitz]

You can wire the woofers parallel, as the signal content going to them is the same. In practice there's no point in doing it. 2 ohm woofers would only give a slightly better result.

[esaru]

Originally Posted by Billfitz

You can wire the woofers parallel, as the signal content going to them is the same. In practice there's no point in doing it. 2 ohm woofers would only give a slightly better result.

All right, in that case I will just settle with the 90w @ 4 ohm configuration. Thank you for sharing your knowledge.

Theoretically though - just trying to grasp the concept - If I’d wire the woofers regularly (1 ch each, 90w) and then add wires to parallel them would that not make it bridged parallel? So 2x 4 ohm becomes 1x 2 ohm. 2 ohm split between 2 amp channels = 1 ohm per channel, and therefore not safe for the match 8dsp?

Just wiring the woofers parallel into 1 channel would result in them sharing the 150w output which obviously is worse than just running 90w at 4 ohm?

[Billfitz]

Rule #1 of Acoustical Engineering: Watts don't matter. Speakers aren't driven by watts, they're driven by volts. Watts only enter the picture when you consider the other factor that does matter, current. When you halve the impedance load the current draw is doubled, which also doubles power draw. Bottom line, engineers don't consider watts, we consider volts and amperes. Marketing departments consider watts.

Bridging isn't a matter of how the speakers are wired, it's how the amp channels are wired. When bridging is possible two amp channel outputs are series wired. That doubles the voltage output. This is where Rule #2 of Acoustical Engineering comes into play: There's no such thing as a free lunch. Bridging doubles the voltage output but it also doubles the minimum impedance load. An amp that has 2 ohm capability per channel will probably have only 4 ohm capability when two channels are bridged. For this reason bridging is typically used only when the total speaker impedance load is 4 ohms or more, depending on the amp. Some amps should only be bridged into minimum loads of 8 ohms.

[esaru]

Originally Posted by Billfitz

Rule #1 of Acoustical Engineering: Watts don't matter. Speakers aren't driven by watts, they're driven by volts. Watts only enter the picture when you consider the other factor that does matter, current. When you halve the impedance load the current draw is doubled, which also doubles power draw. Bottom line, engineers don't consider watts, we consider volts and amperes. Marketing departments consider watts.

Bridging isn't a matter of how the speakers are wired, it's how the amp channels are wired. When bridging is possible two amp channel outputs are series wired. That doubles the voltage output. This is where Rule #2 of Acoustical Engineering comes into play: There's no such thing as a free lunch. Bridging doubles the voltage output but it also doubles the minimum impedance load. An amp that has 2 ohm capability per channel will probably have only 4 ohm capability when two channels are bridged. For this reason bridging is typically used only when the total speaker impedance load is 4 ohms or more, depending on the amp. Some amps should only be bridged into minimum loads of 8 ohms.

Thank you for the thorough explanation! I shall happily connect them individually to one channel each, and now with a better understanding of why this is preferable.

Another question regarding crossovers. I found a used set of Audio System mids and tweeters. They come with 2 crossovers labeled FWK MID and FWK TW EVO. Are these satisfactory or would you recommend building my own crossovers according to the specifications you posted?

FWK TW EVO
AUDIO SYSTEM Crossover X-SERIES
6 dB tweeter cable crossover with 3-times acoustic adjustment
very compact
with high-quality HIGH AUDIOPHILE-capacitor and foam protection

FWK MID
AUDIO SYSTEM Midrange Crossover
6 dB midrange cable crossover (bandpass)
very compact
with 100uF capacitor, high-quality FERRIT-coil and foam protection

https://en.audio-system.de/products/...ies/crossover/

Part of this kit:
https://en.audio-system.de/wp-conten...ERIES-EVO2.pdf

[Billfitz]

6dB filtering is inadequate. It's what the stock BMW arrangement uses and is one of its major shortcomings. I designed my own crossover. I posted this a few years ago:

The original OEM setup doesn’t have crossovers between the midranges and tweeters. It only has a cheap NPE capacitor that keeps the midrange out of the tweeters. It doesn’t do a very good job of it, leading to distortion. There’s no filtering on the midranges to keep the high frequencies out of them, so literally a quarter of the high frequencies are lost going to the midranges that can't reproduce them.

This third order high pass filter is sixteen times more effective than a single capacitor in blocking midrange from the tweeters.



The low pass filter is second order. By using a third order high pass with a second order low pass polarity issues are avoided.



These are the parts:

8.2uf cap: https://www.parts-express.com/Dayton...acitor-027-426

20uF cap: https://www.parts-express.com/Dayton...acitor-027-436

0.1mH coil: https://www.parts-express.com/Dayton...r-Coil-257-020

0.2mH coil: https://www.parts-express.com/Dayton...r-Coil-257-024

These filters tap into the wiring to the drivers. The tweeters normally plug into the midranges, so you have to create a ‘Y’ in the wire leading to each midrange. One leg of the wire goes to the low pass filter and then to the midrange, the other goes to the high pass filter and then to the tweeter. The capacitor on the factory wire between the midrange and tweeter is discarded. The components can be hot melt glued and plastic zip tied to perf boards for placement in the doors.
https://www.parts-express.com/Red-Pe....5-x-5-260-180