BECtoo
Well-Known Member
There has been a lot of discussion on the use of the Klipsch K-53 Ti (titanium) midrange diaphragm in some earlier Klipsch speakers like the Forte 1, Forte 2, Heresy 2, Chorus, Chorus 2, KLF-20, KLF-30, Quartet and probably some others that use that style of midrange diaphragm.
This titanium midrange diaphragm was made by Klipsch and is used in the current production Heresy 3 and Cornwall 3 speakers. The driver sounds very good in isolation and in the Heresy 3/Cornwall 3 speakers and is, I would think a driver superior to the phenolic version.
Now, the question is (or should be): Does changing to this titanium diaphragm make sense for the speakers that originally had phenolic midrange diaphragms?
I have been asking myself that question for quite some time and just never seemed to have the time to get around to working on it. Well I did some of that today.
The picture attached is an FR trace of the Klipsch K-53Ti on the K-701 horn. Also on the same trace is the exact same driver and horn with just the diaphragm changed to an OEM Klipsch phenolic.
The red trace is the phenolic and the green trace is the titanium.
First thing to notice is that the curves fit with each other pretty well over most of the frequency range with a bit more output on average for the titanium. Next thing to notice is how high the frequency goes for each before the natural roll off of the diaphragm. You can see that the phenolic rolls off steeply at 6khz. So, if we bring the tweeter in at 6khz also, this makes perfect sense for the crossover in, for instance, the Forte 1, which uses this natural roll off to match up to the tweeter.
So, what happens if we use the Klipsch Titanium diaphragm in place of the phenolic without any change to the crossover? You can see that the titanium diaphragm does not roll off naturally at 6khz, but instead is actually increasing in output to 7.36khz. If we consider how the crossover summing works, we expect each of the two signals we are summing (midrange and tweeter) to be about 6db down at the summing frequency so that they sum flat at the crossover point. With the substitution of the titanium diaphragm, I think we would see a 6db or greater "hump" in the acoustic output at around 6 to 7.5khz.
Some will now probably want to know how to correct the crossover to use this titanium diaphragm and have the summing work right. That one is tough. The midrange needs a pretty steep slope bandpass for the midrange. I would have to set up the midrange and tweeter and see how they actually sum acoustically and design a bandpass filter to compensate. I have a gut feeling that this bandpass might have to be at least as steep as 3rd order to completely get the summing right. That adds a lot of parts.
A simpler approach that might work is to simply let the midrange roll off naturally at it's higher frequency and move the tweeter crossover frequency up to 7.5khz. That would not add any parts, just change the tweeter filter parts to different values.
Before closing this, I want to make sure to make one more point. I have not said changing this phenolic to a titanium and keeping the original crossover would not sound good. I have just made one small step toward identifying what might be a problem. The next step is to determine how the drivers actually sum acoustically. That is a much more difficult but would tell much more about how this works.
Bob Crites
This titanium midrange diaphragm was made by Klipsch and is used in the current production Heresy 3 and Cornwall 3 speakers. The driver sounds very good in isolation and in the Heresy 3/Cornwall 3 speakers and is, I would think a driver superior to the phenolic version.
Now, the question is (or should be): Does changing to this titanium diaphragm make sense for the speakers that originally had phenolic midrange diaphragms?
I have been asking myself that question for quite some time and just never seemed to have the time to get around to working on it. Well I did some of that today.
The picture attached is an FR trace of the Klipsch K-53Ti on the K-701 horn. Also on the same trace is the exact same driver and horn with just the diaphragm changed to an OEM Klipsch phenolic.
The red trace is the phenolic and the green trace is the titanium.
First thing to notice is that the curves fit with each other pretty well over most of the frequency range with a bit more output on average for the titanium. Next thing to notice is how high the frequency goes for each before the natural roll off of the diaphragm. You can see that the phenolic rolls off steeply at 6khz. So, if we bring the tweeter in at 6khz also, this makes perfect sense for the crossover in, for instance, the Forte 1, which uses this natural roll off to match up to the tweeter.
So, what happens if we use the Klipsch Titanium diaphragm in place of the phenolic without any change to the crossover? You can see that the titanium diaphragm does not roll off naturally at 6khz, but instead is actually increasing in output to 7.36khz. If we consider how the crossover summing works, we expect each of the two signals we are summing (midrange and tweeter) to be about 6db down at the summing frequency so that they sum flat at the crossover point. With the substitution of the titanium diaphragm, I think we would see a 6db or greater "hump" in the acoustic output at around 6 to 7.5khz.
Some will now probably want to know how to correct the crossover to use this titanium diaphragm and have the summing work right. That one is tough. The midrange needs a pretty steep slope bandpass for the midrange. I would have to set up the midrange and tweeter and see how they actually sum acoustically and design a bandpass filter to compensate. I have a gut feeling that this bandpass might have to be at least as steep as 3rd order to completely get the summing right. That adds a lot of parts.
A simpler approach that might work is to simply let the midrange roll off naturally at it's higher frequency and move the tweeter crossover frequency up to 7.5khz. That would not add any parts, just change the tweeter filter parts to different values.
Before closing this, I want to make sure to make one more point. I have not said changing this phenolic to a titanium and keeping the original crossover would not sound good. I have just made one small step toward identifying what might be a problem. The next step is to determine how the drivers actually sum acoustically. That is a much more difficult but would tell much more about how this works.
Bob Crites
