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Need help to add high frequency to my Single Driver speakers.

Home Theatre Systems
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Apr 4, 2019
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Hi All,

I own a Line Magnetic field coil LM-755i speakers which has wonderful mid waves, however highs are rolled off. Even though those are prefect for most of my listening list, just wanted to see how would they behave if I add a tweeter to add the high frequency flavor to my beauties..

Looking forward to see some support to design and select components needed to add the high frequency as I'm technically weak.

Criteria: No compromise on the Mids which are extremely good in the current form and we should ensure any addition will not add any fatigue.

Thanks,
Vinod
 

yogibear

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Cross above 10k, experiment and try with a single cap but the tweeter must be closest possible to the driver, FC in your case and make it up firing, facing the ceiling. Small ribbon tweeter or any supertweeter will be good but must be able to handle first order slope. Make sure the tweeter does net get to handle any frequency detrimental to it since a single cap is a first order slope.

A much better approach is to go active with 24dB and start crossing above 10k and see where you like it.

In any case, the tweeter must be up firing.
 

newlash09

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Hi

You could consider adding a super tweeter. A lot of companies make super tweeters to compliment single driver speakers. Townshend comes to mind immediately. All the best
 

adas

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Cross above 10k, experiment and try with a single cap but the tweeter must be closest possible to the driver, FC in your case and make it up firing, facing the ceiling. Small ribbon tweeter or any supertweeter will be good but must be able to handle first order slope. Make sure the tweeter does net get to handle any frequency detrimental to it since a single cap is a first order slope.

A much better approach is to go active with 24dB and start crossing above 10k and see where you like it.

In any case, the tweeter must be up firing.
With the tweeter up firing wont there huge on axis and off axis issues , the idea of getting the tweeter as close as possible to the midrange driver is to emulate a point source ... Also add just a capacitor won't do anything to match the sensitivity of the tweeter to that of the mid range , if padding is required atleast a resistor will also be required.
 

yogibear

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With the tweeter up firing wont there huge on axis and off axis issues , the idea of getting the tweeter as close as possible to the midrange driver is to emulate a point source ... Also add just a capacitor won't do anything to match the sensitivity of the tweeter to that of the mid range , if padding is required atleast a resistor will also be required.
Check some YouTube videos on how to add a supertweeter to full range driver. An up firing yields the best frequency response and blends with that of an FR, else it’s much better off with the FR alone. It’s always a better choice to use a super tweeter with much higher sensitivity than the FR. A single cap is what everyone has settled with, However my own experiments told me, it better to go active. (BTW I don’t use any tweeter and don’t miss any of highs. In frequency response above 10k, minimal distortion matters more)

However in any case, passive or active, up firing is must. Danny Richie of GR Research published measurements on all iterations and up firing is optimal. Google it.

When I said closer to driver, I meant it’s frame. Of course coaxial is way to go but most coaxial cross much lower than where most FR roll off. The magic of FR is missing then. Coaxials are 2 way with optimal placement of tweeter.
 

Kannan

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There are two aspects to look at. The f/s and the spl of the tweeter.
The easiest approach with a full range driver is to use a low profile tweeter 8 ohm preferably) which has an f/s of around 5 to 6 khz. Cross it with a 1.8 to 2.2 microfarad audiograde capacitor in series to the +ve terminal. Additionally you can mount them on an axial pod to angle them to your liking with respect to the listening position.

You can additionally send the signal through a separate amp aswell to the tweeters so that you can also attenuate the output to match the spl of the full range driver.
 

yogibear

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I did try adding a tweeter just at the centre of the dust cap of the FR. It was a bad move, even given small tweeter size and crossed around 7K. The FR lost its airiness with its cone / dust cap being partially eclipsed by the tweeter.

On the contrary, tweaking the source helped in HF extension and even in bass and FR started doing an amazing job without need of a tweeter. It was hard to believe that nothing in the line up changed except source, to make such a huge difference in sonics.
 

greenhorn

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There are two aspects to look at. The f/s and the spl of the tweeter.
The easiest approach with a full range driver is to use a low profile tweeter 8 ohm preferably) which has an f/s of around 5 to 6 khz. Cross it with a 1.8 to 2.2 microfarad audiograde capacitor in series to the +ve terminal. Additionally you can mount them on an axial pod to angle them to your liking with respect to the listening position.
This is what i did. I got a tweeter with similar spl as the fullrange, then added it with a cap in series, and tried different capacitor values for crossover frequency until i got a sound I liked
 
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On the contrary, tweaking the source helped in HF extension and even in bass and FR started doing an amazing job without need of a tweeter. It was hard to believe that nothing in the line up changed except source, to make such a huge difference in sonics.
You mean you added a equalizer and increased the High and low ?
 

yogibear

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You mean you added a equalizer and increased the High and low ?
No. There is no equalizer or tone control in my setup. Just worked out better way to stream online or play lossless. JRiver in my case. Earlier it was volumio.
 
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