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Old 21st March 2013, 12:26 PM   #1
zog666 is offline zog666  Australia
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Default active two way with HF144 compression driver and LTH142 horn

Hi,

After a few years being happy with my "classic" econowave build, I've decided to gradually replace them with some active two ways in a similar, but hopefully "more is better" vein.

I've ordered in a pair of Faital Pro HF144 compression drivers with corresponding LTH142 horns. I've yet to settle on a matching low frequency driver - most likely a 15", but I am getting some instant gratification thanks to MiniDSP by just sitting my existing speakers on their sides with the new horns & CDs on top:

Click the image to open in full size.

One thing I have noticed is for both of my HF144 drivers, although my measurements are relatively close to the factory response graph, mine have a big "notch" at about 15Khz not present in the factory curve:
my measurements (at 1M, both "left" and "right" smoothed @ 1/8 per octave ):
Click the image to open in full size.

response from the FaitalPro site:
Click the image to open in full size.
although I dont think I can hear up that high, it's still kind of annoying :-)

Col came over and we checked them with woofertester3 and they test out fine impedancewise.

Can this be explained by room effects or me not measuring the same was as Faital do? Should I even care about a notch in frequency response up that high?

I've got more involved discussion in a blog post here:
beyond econowave : Faital Pro HF144 compression driver with LTH142 Tractrix horn | MiniRIG

A gated measurement, of both HF & LF drivers (crossed at 900hz) with some miniDSP correction shows the HF response in a bit more detail:
Click the image to open in full size.

apart from the above they are sounding quite good just working with my existing speakers, looking forward to the next step of choosing some woofers in a decently sized bass reflex box to go with them.
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Old 21st March 2013, 12:39 PM   #2
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I think the notch at 15k is still there in the Faital Pro's measurements.... it's just heavily smoothed over. Try 1/3 octave smoothing on your measurements, then compare the two. I think you'll find they are more similar than you think.

Joe
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Old 21st March 2013, 01:28 PM   #3
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I wouldn't worry about the notch at 15kHz. There's very little information up there anyway.

However, I would take a closer look at the hump centering at 500Hz (bottom plot). I find this makes voices nasal.
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Old 21st March 2013, 01:32 PM   #4
zog666 is offline zog666  Australia
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Quote:
Originally Posted by Josephjcole View Post
I think the notch at 15k is still there in the Faital Pro's measurements.... it's just heavily smoothed over. Try 1/3 octave smoothing on your measurements, then compare the two. I think you'll find they are more similar than you think.

Joe
The factory graph - available in more resolution at http://www.faitalpro.com/products/fi...4_curves_8.pdf seems to have a few more angular bits in it that would indicate to me that it isn't that smoothed... I could just email them and ask I how they made it I suppose. But yes, there is kind of a sign of the notch there.
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Old 21st March 2013, 09:36 PM   #5
zog666 is offline zog666  Australia
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Quote:
Originally Posted by Michael Chua View Post
I wouldn't worry about the notch at 15kHz. There's very little information up there anyway.
It's funny in another thread (re: one of my DACs) I'm discussing the DAC not being able to do 192khz while handling 96khz fine.. but a simple test with sine waves generated in audacity and my 45 year old ears struggle to hear anything beyond 14khz.

Quote:
Originally Posted by Michael Chua View Post

However, I would take a closer look at the hump centering at 500Hz (bottom plot). I find this makes voices nasal.
I've got a later iteration of my MiniDSP crossover config which I need to add where I'm crossing over at 500hz instead of 900hz (which the LF144 appears to handle just fine!) and have a bit of attenuation around 500. But as I did my measurements indoors I'm guesstimating as I'm getting a lot of room effects around the crossover point in the measurements (auto gating according to Holmimpulse).
Some outdoor measurements are on the cards to reomove room effects, especially if some smaller temporary woofer enclosures become available, my 120L econowave cabinets weren't made with ease of moving in mind :-)
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Last edited by zog666; 21st March 2013 at 09:40 PM.
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Old 22nd March 2013, 02:15 PM   #6
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Quote:
Originally Posted by zog666 View Post
... but a simple test with sine waves generated in audacity and my 45 year old ears struggle to hear anything beyond 14khz.
Personally, I'm not bothered by sine tones at 15kHz. What I'm really interested in are Tone and Harmonics. It is subjective but that's what my speakers are for, my listening pleasure.

The bump at 500Hz could be due to floor bounce. If the voices doesn't sound nasal, it's fine. Measurements can be deceiving sometimes.
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Old 23rd March 2013, 12:59 AM   #7
zog666 is offline zog666  Australia
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Quote:
Originally Posted by Michael Chua View Post
Personally, I'm not bothered by sine tones at 15kHz. What I'm really interested in are Tone and Harmonics. It is subjective but that's what my speakers are for, my listening pleasure.
That's essentially what I said. But I am a follower of the Zilch (of Econowave) mantra of "more data, less wank", and these compression drivers have a manufacturer advertised response up to 18khz.
I am listenening to, and enjoying them :-). But then again they can be used in a non PA setting well under the 800hz frequency mentioned as well.

Quote:
Originally Posted by Michael Chua View Post
The bump at 500Hz could be due to floor bounce. If the voices doesn't sound nasal, it's fine. Measurements can be deceiving sometimes.
agreed.

I have found a few mentions of German web sites that appear to agree with my measurements according to google translate - I'll move on with other fun stuff.

One of these is I've ordered some inexpensive Pyle PH916 constant directivity waveguides - be interesting to compare them with the Faital Pro tractrix horns.

I also want to do some directivity heatmap plots. as far as I can tell there is no free softare solution to do this, the easiest path to getting it done is the paid version of ARTA. This will allow me to fully compare the Faital and Pyle waveguides, and get the crossover point with the LF drivers sorted out.

Also have been looking at 15" drivers with better bass than the Eminence Delta 12LFA. I'll set them up in a simple bass reflex enclosure.

Possible candidates include:
Beyma 15B100R
Beyma SM115/N
RCF LF15N401
B&C 15TBX100
Selenium 15WS800
Lorantz C390X B1
(etc).. i.e. a range of high efficiency "PA" drivers with lower Fs that look suitable for hifi use as well, that I can cross over at between 500 and 1000 Hz
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Old 28th March 2013, 07:17 AM   #8
zog666 is offline zog666  Australia
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I got a pair of lovely Australian made Lorantz C390X B1 15" bass drivers from ebay in very good condition, so these will make up the low frequency part of this two way project.
Apart from the drivers themselves the seller added in a bonus PA bass reflex cabinets he had them mounted in - while not the best quality it is great they came with them as I can get some instant gratification and start using them straight away:
Click the image to open in full size.
Their design is quite handy, as turned upside down the 15" driver is very close to the waveguide, which is how I want the good enclosure I will build to be arranged.

For now I've bypassed the basic PA crossover in the unit and hooked up directly to the amp via some cables fed through the bass reflex ports.

In room measurements are pretty similar to the old drivers, as below 600hz there are a lot of room effects - when I get time and decent weather I'll do some outdoor measurements.
So I now have an even more "PA" looking two way active system with these temp. boxes:
Click the image to open in full size.

Specs for the driver are at this link:
http://www.lucasmiles.com.au/content...C390X-B1-8.pdf
Sold here, though I got them substantially less than this on ebay :-)
Lorantz Bass Speaker C390X B1
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Old 28th March 2013, 11:48 AM   #9
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As to the dip at 15khz....I agree you're probobly not missing much BUT for the sake of the discussion, I'd try mounting the horn on a 36" square of baffle and re measure....bet it smooths out quite a bit.

That Faital pro horn looks like a winner!
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Old 28th March 2013, 01:19 PM   #10
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Are you sure you didn't see any blips in the impedance around 9-10kHz?

Try measuring the speaker on the floor near the middle of your room pointing at the ceiling to get down to crossover range indoors.

Btw, this looks like you're heading for directivity approximating a smooth taper from 360 to 60, which is quite a bit different from the 360-to-90-and-then-hold-it CD type of design.
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