Hi guys, i wanted to ask your opinion regarding an upgrade i am planning on my R50 front speakers. The drivers that i chose are the Gladen RS165 midbass drivers, and the OEM Harman Kardon tweeter/midrange (already have the HKs, planing to buy the Gladens). Reason that i chose the OEM midrange/tweeter is because it's the only way to have a midrange without cutting the door card in a R50/R53. The OEM R50/R53 system has a tweeter next to the door handle, but the HK system is two in one, midrange and tweeter. My problem is this : I don't know what frequencies to cross over to the mid/tweeter. I was thinking to cross at 400Hz, and transfer the soundstage up high, as it's down low at the moment. I tried to find what the OEM crossover frequency is through the HK amp, but i can't find any info for the R53, on the other hand Integral Audio has provided usefull info for the R56 HK system, but i can't find anything for the R50/R53.

Waiting for opinions/experiences!

Just for reference, here is the standard hifi tweeter :



And this is the HK tweeter/midrange :

 

That's impossible to answer without measurements on the drivers at least, preferably in-vehicle. Do you have the HK system, or did you just buy the HK drivers separately?

What you are proposing is problematic in either case. As you are aware, there is dramatic signal shaping in the HK amp. The mid/tweeter unit is connected to a single channel on the amp, with both speakers getting the same (shaped) signal. [See attached image, mid/tweeter signal from amp is in red, the door woofer is green. This is from an R52, but the front output is nearly identical to yours and uses the same drivers.] The midrange driver gets the entire signal, and there is a capacitor on the tweeter to block the lower frequencies (probably from about 8k down, I don’t have the #’s handy). Most of the shape of that curve is speaker correction – trying to reduce the response in areas where the mid and tweeter are producing the same frequencies to varying degrees of effectiveness, and one or both are also ringing (break-up mode).

You can see that the factory crossover point is at about 870Hz from mid to woofer – that “mid” is closer to a tweeter than a midrange. Even at that, the significant bump between 1-2kHz is almost certainly trying to boost the dropping response of the midrange.

If you were to try to use that HK mid/tweeter with an aftermarket amp, you wouldn’t have that shaped signal, and your final response would reflect the inverse of that curve. Not good. That mid/tweet is also a very poor unit to begin with.

You’d be better off trying to find a good tweeter with a rear chamber that gives you a low Fs (shoot for 800Hz), and just cross it over as low as you can – keeping in mind that the lower you push the tweeter the lower your power handling and the higher your distortion. You are correct that the higher cross point buries your soundstage, but your options are limited here.

 

Hi Kevin, great response!

I actually don't have an HK system, but i am preparing an active setup with DSP in the headunit (Pioneer 80PRS). It's expected that a midrange this size wouldn't perform like a 3-4" mid, but isn't it still better than a single tweeter trying to cover all the spectrum, from 1k let's say and all the way up to 20k?
If the bump in the 1-2kHz area is DSP boosted, can't i turn it to an advantage? As if not boosted/equalised, then i guess the 1-2k area would sit somewhere near the top end of the frequency range , right? Boosted it's up to 5db up compared to the 3-10kHz on the graph, depending on the specific frequency. So, i could let the mid roll off naturally down to 1k and low pass it there, or not?
Then ofcourse comes into play the balance with the midbass, but this in an active flexible system can be adjusted from the gain of each channel from the amp (midbass/midtweeter).
I looked into a lot of component 2 way sets, and the lowest crossed i can see is around the 2.5k area. That's still very bad for the sound stage, as half the important spectrum is covered by a driver that's down low on the door.

 

No, you'd be much better off with just a good tweeter. The HK "mid" won't play any lower than a good tweeter with a rear chamber. The HK mid/tweet is two poor drivers - with all of their weaknesses (poor, ragged freq response, high distortion, etc) - compounded by the fact that there is no LP filter on the mid and only a cap on the tweeter.

It's probably boosted because it's already rolling off at 2kHz, which would make that the top end of the usable frequency range. You'd have to high-pass it there, or boost it as they have (also not ideal, for all the reasons mentioned previously).

That's due to the tweeters they are using, which is why I am stressing that you would need to use a good tweeter with a rear chamber (to achieve a low Fs). It's still not ideal - you are going to bury the critical low mid band in the floor unless you use a proper mid - but it is still much better than trying to use the HK unit, which isn't going to even get you as low as a good tweeter anyway and has loads of other problems to boot.

 

Would you recomend any tweeter to cover these specs?

 

Not really. We have our drivers made, so I'm not ultra-familiar with off-the-shelf offerings from most vendors. That said, Morel used to make some models that would fit the bill. Something along these lines: http://www.madisound.com/store/manua...l/mdt%2022.pdf would get you down to 2kHz safely. A general rule of thumb is that you can push the cross down to 2 to 2.5 times Fs. That particular driver has some response issues, so I wouldn't try it, but if you dig you should be able to find something that does what you want, fits your budget, and fits in the mounting location (check your mounting depth, and you're prob going to have to do some cutting/modifying).

EDIT: Here's a better bet from Morel - http://audio-hi.fi/download/pdf/More...ter_MDT-39.pdf. If you use a higher order crossover you could potentially push that down to 1.5kHz.

SEAS has this: https://www.madisoundspeakerstore.co...-dome-tweeter/ That's as shallow as you'll find and still get a rear chamber. With a high order cross, you could prob push that down to 2k, maybe lower. You'd have to model/test. If it were me in your position, working with those constraints, that would probably be my selection.

That should give you a starting point. Dig, and ye shall find...