Adding a tweeter to DX3?

[KMMM]

Hi pdan

Thank's

Yes i Know. My Lowthers have been playing since May, I think.
They are probabaly still not propperly run in though.
What I ment is that I'd like to try (almost) anyting to check if it will be even better
Like adding a sub and a super tweeter.

Kaare

[MJK]

Originally posted by KMMM
Looks like I'll be trying The Fostex super tweeter.
One question though:

The Lowthers in the MLTL has a bump in Martin's frequensy response diagram - arround 7k to 15k in this design.
could this be the reason I get listening fatigue after a while?
After all it's at least 5dB.

The question is: would it be possible to dampen this bump?
Would it be best to cross over the Lowthers at 7-8k and then 8-9k on Fostex (ca 95dB)?
Then again may be there are better wways to do it?

What I found is that while the on axis response has some humps, the off axis response was fairly smooth. If you are listening 15 to 30 degrees off axis you should not be subjected to the peaks seen in the on axis reponse.

If you have the BSC circuit in place, using the resistance value you indicated above, I am a little surprised that you are experiencing listener fatigue. I have listened to my pair for hours at a time without a problem. If it is too harsh you could increase the parallel resistor by an ohm or two until it sounds closer to what you like.

I would not add any crossover filter to the Lowther, I would just use the Fostex tweeter and pad it down to match the Lowther with the BSC and then a simple first order crossover using a cap in series. This is essentially what I did with the OB speakers but I did not need to pad the tweeter down since the system efficiency already matched the tweeter's efficiency. I don't know what values to recommend since I have not done this before with the DX3 in the ML TL enclosure.

Originally posted by KMMM
I realize that the frequensy response diagram I've been looking at might not be
the final one...(?)
MJK made a revision to the Baffle Step Correction Circuit.
I made the updated one.
Is there an updated frequensy response diagram some where?
Are there a lot of difference in the new Correction Circuit?

I think that the significant change I made to the BSC circuit was reducing the inductor value, all this does is move the point at which the BSC kicks in up a little in frequency. The parallel resistor recommendation remained the same, the amount of correction stays constant. The only other thing I did was add a cap in parallel with the BSC to restore some of the high frequencies, does you filter include this cap? If you remove the cap does it help with the listener fatigue?

I believe all the measurements I made are in the article so there are no other results to show.

I think that if you decide to add a super tweeter you will just need to experiment with different amounts of padding on the tweeter and different capcitor values until you have the combination that sounds best. There is no right or wrong answer, it just needs to sound good to you in your room with your system.

Hope that helps,

[KMMM]

Thank you for your reply MJK. It was very clear and easy to understand

I'll go a head an try the tweeter and try to pad it at 95dB for a start, together with a 1-1,5cap.
I have noticed that the "bump" get's a bit smoother off axis. But to much I feel ther's something missing. I've got a 12ohm resistor some where - from Duelund.
I'll try to replace that with the 10 ohm I'm using in the BSC now.

Thank's again!

I'm looking forward to tweeking a bit

Kaare