9972RS

question for the audio gurus.

so, I have a base audio 991.2 which does not have a separate amp in the passenger footwell. The PCM headunit is the amp. Besides upgrading the tweeter, what else can I do for the mid and woofer? ie, w/o adding a separate amp. would this be adequate or just underpowered w/o a separate amp? trying to make the upgrade simple, no re-wiring to new amp.

991C2S88

Does anyone have feedback on how this compares to the 991.2 Bose tweeters? I feel the .2 Bose is improved compared to the .1, so was wondering if these sound much better than the .2 Bose. Thanks

BLKFLAG

IMO the Daytona are a huge improvement, as echoed by other users who did the mod. Bose can modulate the sound to appear decent on low levels or with certain music, but in general the OE tweeter belongs in an alarm clock. The Dayton’s are just smoother, more capable, and cleaner sounding, so less listener fatigue when you’re pushing the audio system. One other way to improve sound for all 991’s would be adding sound dampening sheets to the inner door panels. This will give all drivers a better acoustic environment and help to reduce mushiness and distortion of the mid and base drivers. Just my $.02

flgfish

Yeah, the Dayton tweeters are much better than the stock Bose tweeters. I don’t think they’ve changed the speaker in the .2, they just changed the amp configuration IIRC.

flgfish

You could always swap out speakers if you don’t mind removing door panels. You’ll also need to make mounting rings... 3d print some, or with a router.

I imagine Parts Express has options. The RS100p may be worth trying for the 4” mid, and I have 3D printer models for the rings on Thingiverse. For the 8” woofer, I’m not sure but we could recommend something if you’re interested. 8” you’d have to use a router for the rings (or a really large bed printer).

991C2S88

Thanks for sharing your improvements on this great mod by the op. Using the stock tweeter top like you did, is a separate capacitor no longer required? Thank you

flgfish

You need the capacitor. It acts as a first-order crossover. In the stock systems, the mids & tweeters are on the same wires/channel. That means that the tweeter needs to be isolated from the frequencies lower than which it is capable of playing.

991C2S88

Thanks for your reply. I see the original Bose tweeter cap has a small capacitor. I was wondering if this by itself is sufficient. Thank you

polobai

Actually if you transfer the cap, the capacitor is also transferred. So yes, you need a capacitor but it’s already there if you transfer the cap.

PJK3

Actually -- I'm not sure this is true anymore. You might not have to print and/or make custom adapters rings for speakers any longer. I stumbled across this site the other day: https://rennspec.com/
Looks like they sell speaker adapters, wiring harness, etc. for many recent Porsche vehicles. Was thinking about replacing my shameful homemade 8" woofer adapters with a set of these....

Carl Over

Hi guys. This is my first post on RL. I decided to try the DIY Dayton tweeter upgrade a go.

i bought the following

-Dayton Audio ND20FB-4 3/4” neodymium dome tweeter, qty 4
-4.7 uf, 100V capacitor, qty 5
-gold 18-16 awg female disconnects, 0.187”, qty 10 pair
-BMW wiring harness, 0.072” wire, 4.5” wire pigtails, AliExpress special, 10 female and 10 male pairs

i bought extras in case I screw up. Or want to replace the rear tweeters. Or make an extra set for someone.

I don’t have access to the car currently and have a few questions.

-the capacitor has diameter of 0.405” and length of 0.771”. Will this fit under the factory spring steel thing?

-the diameter of the speaker is 1.416”. Does this seem big? I think someone measured the diameter of the Sound Plus system but I haven’t seen the Bose diameter listed.


I’d like to use the female disconnects on the speaker end of the wiring harness. My last soldering experience 20 years ago does not give me lots of confidence.

Would I remove say 1.25” of the current wire that is in the harnesses and solder in the capacitor. I think in this post someone mentioned that the cap didn’t care where it lives. The Dayton speaker has a terminal that has been marked red. Any thoughts?

Thank you very much in advance for the help with this project!

Carl Over

So I did a bit of digging around on capacitor sizing and came across this formula.

Capacitor size= 0.159/(F x Rh), where Fs<F<Actual crossover frequency and Rh is the dc ohms or Re. Using a value for F that is twice Fs is reasonable.

Using the specs listed in the Dayton Audio spec sheet here


using F=4000hz and Rh of 3.2 ohms, gives 12.4uf capacitor size.

So it seems like the 4.7uf capacitor for the Bose tweeter while appropriate for the Bose cheap tweeter, is likely insufficient for the Dayton ND20FB-4.

Parts express has the following capacitors:

15uf, 100V
https://www.parts-express.com/15uf-1...citor--027-344

12uf, 100V
https://www.parts-express.com/12uf-1...citor--027-342

I will likely order the 12uf capacitors just because. Hope this helps.

Wolpertinger

I'd be very interested to hear which capacitor is the one to use. I'm going to install these tweeters as well. I have the tweeters on hand, just waiting for capacitors now. I've ordered both 12uf and 4.7uf so I have both on hand.

Carl Over

Ill go with the 12uf based on my calculations. Need to order these tomorrow.

Rennspec.com

Yes, 12uF would be an ideal cap size for these tweeters. A 4.7uF cap would result in a high-pass filter of ~10 kHz, which isn't ideal.

There is a handy calculator which can be found here.

https://www.pad2pad.com/calculators/...y-capacitance/