Looking for advice on adding a super tweeter to high efficiency mono speaker

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I built some large leCleach horns several years back for a high efficiency horn system for my home. Shortly after finishing the horns my daughter was born, and they sat in my basement for quite a while. I just put in one as a mono speaker along with an 18sound 15mb700 in my pottery studio. They sound great, if maybe slightly rolled off on top... when I am standing directly in front of them. Unfortunately when I am working in my studio I am rarely standing in front of them. They sound quite rolled off on top when off axis.

Obviously this horn isn't ideal for my studio.... it's what I have though. I'm hoping that maybe crossing the horn over to a super tweeter around 3-5khz will help. I have extra channels on the amp and minidsp. Right now the horn is crossed over at 600hz, and naturally rolls off around 7khz.

I'm on a limited budget, though I wouldn't mind making a very small leCleach horn to match the big one. Maybe a smaller compression driver on a 2khz horn? ... any advice would be greatly appreciated!
 

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Directivity can be the achilles heel of the otherwise good LeCleach horn. Another smaller LeCleach isn't going to 'match' it. For a number of reasons it may be tricky to cross at 4kHz. Adding a super tweeter can be easier when crossed higher as it is less easy to localise. Crossing lower wants a different approach.
 
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that's a beautiful horn !


re: Piezo tweeter, the small element tweeters are like a 0.16uF capacitor. A step-up transformer arrangement can boost 2.83v sensitivity to ~103dB or maybe a bit better

Goldwood 1005 have some variance

MMJ's schematic for a 70v matching transformer
An externally hosted image should be here but it was not working when we last tested it.


Network I used with a KSN1016 (DJK suggested the Zobel / stepup)
image.jpg

E7wNxVS.jpg


Goldwood 1005 - no network or step-up

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1WVE21o.gif
 
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AllenB, I know matching directivity might be problematic. I would be curious as to any other thoughts you might have on that. Crossing higher as in 7khz? You mention crossing lower would require a different approach. What would that look like?

Freddi, PeteMck I've never worked with piezo tweeters... certainly the price is right. I'm not super literate when it comes to electronics... what kind of transformer is recommended?
 
A popular choice among the vintage horn users is Jensen RP302, the same horn super tweeter used in the legendary Jensen Imperial. It seems to be popular that adding this Jensen to $$$ Western Electric 555 mid driver that also roll off around 7k. Sweeter sound than another popular JBL ones.
 
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Crossing higher as in 7khz?
Yes, this can help. Your corner placement may create some compromise though.
You mention crossing lower would require a different approach. What would that look like?
I would normally consider finding a point on the LeCleach dispersion where it is, say, 90 degrees give or take and continue this with waveguided treble. This could fix your issue, if you can work with the corner.
 
regarding transformers, if using MMJ's scheme, "this" would do

https://www.parts-express.com/70v-15w-speaker-line-matching-transformer--300-039

IIRC, I used a 25 volt 15 watt rated Edcor transformer on it 5 watt tap

LeSon made pretty good piezo tweeters with a built-in autoformer which were probably 102dB/2.83V - I can't find those on Ebay - only Leson "style" rated 92dB.

Here's a 25 volt transformer with 5 and 10 watt taps for about 6 bucks - you probably do need the 8R + 100uH inductor Zobl
network. That's a cheap air-core in that size

http://www.krp.com/10-WATT-25-VOLT-MATCHING-LINE-TRANSFORMERS-WITHOUT-LEADS_p_1201.html

an L-pad can feed the transformer in case ~102dB/2.8v is too loud. The 56 or so ohm resistor to the piezo is to keep
the impedance from dropping too low at high fequencies.

E7wNxVS.jpg
 
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here's a post from DJK at Audioasylum's High Efficiency Speaker forum regarding piezo arrays (and a 4k5 crossover -suitable with one piezo for Klipsch style applications - with a DPDT switch, it changes from 2-3rd order highpass)

"The KSN1016A behaves like a lossey 0.13µF capacitor, and the response actually rises above 16Khz or so.

Use a 75Ω resistor in series with each tweeter. This does several things. It damps the resonance of the tweeter by lowering the Q a bit. It rolls off the energy where the response of the tweeter starts to rise. It makes the load more amplifier friendly.

Three of the piezo and resistor combos in parallel will be about 50Ω around 16Khz, so hook them up to the 10W (62Ω) tap on the 25V line transformer.

I would try a zobel of around 6.8Ω and 100µH across the 8Ω tap of the transformer. The 6.8Ω and 75Ω are standard E24 (5%) resistor values.

This should get you close to an 8Ω load for your crossover network. If I need a 4Khz network I generally go 18dB, 3.3µF + 10µF + 0.25mH. If I need a 7Khz network I generally go 12dB, 2.2µF + 0.25mH.

A dual use network may be constructed with a SPDT switch and a 0.25mH + 1µF + 2.2µF + 10µF. The switch shorts out the 10µF or parallels the 2.2µF and the 1µF."
 
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Before recommending a super tweeter, I would like to know what driver you're using with the horns. (I couldn't see anything mentioned about the driver.) Perhaps this could be replaced for something with greater frequency range.

I'm using a Radian 835. I know there are better drivers out there, but I'm on a budget and I found my Radian 835 for cheap on eBay. 1.4" drivers get expensive quick!

Also a new driver won't help with getting a wider dispersion in the upper frequencies as I believe that has more to do with my horns.
 
Joseph, do you have any spare speakers or just tweeters handy that you could experiment with?

You might be surprised by how little you need. Some people use 'flooder' or 'ambience' tweeter(s) pointed at a wall or ceiling, so the HF is diffuse and relatively low in level.
I've given it a try myself (not in my current setup), and it filled in the gaps better than I had expected.

To me, quiet and diffuse HF sounded pretty good, but when I tried a normal (fairly big) midhorn + HF horn setup, it measured flat, but didn't seem as natural. Your taste / equipment / whatever may mean you don't agree, but I think it is worth a go, particularly if you already have a tweeter handy.
 
I don't really have any tweeters here... I've got a 4" full range tangbad laying around. You mention that you tried a large mid horn along with a hf horn and didn't like it. What did you end up using above your large horns. Right now I'm leaning towards a small 1" compression driver simply for the flexibility. I could change dispersion with different horns, along with more options on lower crossover points. I would try for 7khz first but would still have the option of a lower crossover down the road.
 
You mention that you tried a large mid horn along with a hf horn and didn't like it. What did you end up using above your large horns.

My complaint might not be universal - in a bigger room, or if I wasn't used to coaxials, I might not have noticed the spacing so much.

The best combo for me was either non-direct HF (tweeter pointed at ceiling) or faux coaxial, with a small HF horn sitting on the inside of the mid horn.
http://www.diyaudio.com/forums/multi-way/290092-tweeter-coaxial-mounting-midrange-horn.html
After the (linked) tinkering, I gave up. I wasn't deeply invested in perfecting this system, since I had other options. I'm now back to using my coaxials for close (indoor) listening, and I moved the midhorn outdoors, where the listening distance is bigger.

I would try for 7khz first but would still have the option of a lower crossover down the road.

Again, this might be listener and setup dependent, but I think the lower the cross, the more obvious the centre-to-centre spacing will be.
 
Well, I've had a change of heart... I'm proud of the LeCleach horns I built, I think they could have been great in my house where I could relax in front of them and enjoy the music. However in the studio, they are certainly not the best solution, seeing as how I am constantly listening to them outside of their admittedly small sweet spot.

So I think adding a super tweeter seems like it might just be a bandaid at best. I'm thinking something like the Seos-24 might be the best solution. The seos-24 is slightly more than I wanted to spend on a tweeter, but seems like the best long term solution. Any other horns out there I should look at? Preferably something around 90 x60 dispersion, that can be crossed over in the 500-600Hz range. Realistically I don't have time to build large horns again. Thanks for all the advice so far.
 
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Seems like a solid choice. The Seos horns are good looking, and measure well (dispersion / polar plots).

If you want to experiment on a budget, this looks about right:
USED P AUDIO PH316 Horn Lens 1.5" Bolt On

So I think adding a super tweeter seems like it might just be a bandaid at best.

Again, if you wanted to experiment on the cheap, there's this bandaid option:

https://www.parts-express.com/peerless-by-tymphany-bc25sc06-04-1-textile-dome-tweeter--264-1028

Independently measured here - looks like the manufacturers specs are right.
Zaph|Audio

Assuming a simple passive crossover, it'd be ~2.5dB down relative to your 15", but that's not bad / a balance that some people prefer.
 
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If you want a narrow vertical, the top and bottom wall parts ought to reach out further than the horizontal needs to, (ie. it shouldn't fit into a flat baffle). 70cm is about the minimum dimension I would choose to tolerate for a waveguide crossing at 500Hz for a minimal compromise system.

Comparing against a ceiling absorber with a round perfect OS starting profile, I think the main benefit of the seos is its ease in working with its dimensions.
 
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