Smallest Footprint Horn and Driver that can reach 500 Hz

@EarlK, which DDS horn is in front of the 802D?

Hi,

It's this DDS CFD1-100 pdf

I'm listening to it , oriented in the vertical ( like Bear used to recommend ).

This is not a constant coverage horn ( by my definition ) / though it still sounds nice.

It's very shallow at 5" ( like many wave-guides this size ) / so it does have that going for it.
- Still, it's not a hip horn to own or talk about :cool: .

:)

PS; FYI, I believe DDS is pretty dormant these days.
 
Thanks for that Earl. I also tried the splash tweeters and found them to be OK. I usually ended up playing them straight ahead, tho, out of guilt or embarrassment something. :xeye:

I suspect that different people hear things differently. I don't get much, if any, spacial benefit from tweeters, more of a tonality benefit. Like warmth on strings.

These Fostex are bullet type tweeters so I feel it's necessary to point them away from me ( no matter what! ).

I do agree that the tweeter "splash" detracts some from the "front-to-back" imaging ( if that is what you implied ).
- Keeping that in mind I'll be working to reduce the tweeters measurable effects ( from say 5K to 10K ).

Here's an REW wavelet showing the relative strength of this tweeter ( relating to the Altec 802 ) and it's shortish time signature/echo ( it's only 18" from the back wall ) .

attachment.php


One thing I'll say is that this is the first time one of these Fostex has remained hooked up longer than 15 minutes ( now, going on about 7 days > so that's a record ).

:)
 
Hi,

It's this DDS CFD1-100 pdf

I'm listening to it , oriented in the vertical ( like Bear used to recommend ).

This is not a constant coverage horn ( by my definition ) / though it still sounds nice.

It's very shallow at 5" ( like many wave-guides this size ) / so it does have that going for it.
- Still, it's not a hip horn to own or talk about :cool: .

:)

PS; FYI, I believe DDS is pretty dormant these days.


Just for fun: try the Celestion with this horn, if you haven't done this before.
It won't play as low as the Altec, but the results may surprise you.


On the other hand, it would be interesting to see the Altec behind this (very cheap) Celestion horn:

cele_h1-9040pe.jpg


An externally hosted image should be here but it was not working when we last tested it.
 
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My experience with oldskool drivers is limited, but experiments by other diy-ers have shown these often don't go well with waveguides.
For this reason it's quite surprising the Faital Pro's appear to be an exception, as they have a conical adaptation horn. I suspect the phase-plug design is a key factor here.

Addition:
The shape (length and flare-rate) of the conical exit part also plays a role.
 
Just for fun: try the Celestion with this horn, if you haven't done this before.
It won't play as low as the Altec, but the results may surprise you.

I guess you want a pic ( right? )

Here it is;

attachment.php


This is a Celestion CDX1-1747 which very closely traces the CDX1-1745.

These 2 models are just about interchangeable ( from a trace perspective ).

See ( the raw, unEQed curves on the PRV, 152i clone waveguide );

2_Celestion_Models_Comparison.png


:)
 

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cele_h1-9040pe.jpg


Worldwide, everyone seems to make that horn.

I bought it under the Sammi ( Korean ) banner 20 years back.

It offers nice ( on axis ) flat response with good lower end loading.

Altec compression drivers ( IME, being ancient designs ) respond best to horns with exponential curves ( like this horn ).

This is a horn ( perhaps ) best listened to in the vertical orientation ( a la Bear ) > I wouldn't use it in the horizontal orientation.

Here's an ancient trace;

802_35480_Diaphragm_2_Sammi_Horn_EQed_notched.PNG


This was done with an non-calibrated test mic / so the HF above @ 9K is about 3db too hot.



:)
 
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It offers nice ( on axis ) flat response with good lower end loading.

Altec compression drivers ( IME, being ancient designs ) respond best to horns with exponential curves ( like this horn ).

This confirms my expectations ;)

Thank you for the plots!


The DDS is certainly not bad, the slightly rough top octave is probably caused by anomalies at the throat.

The original QSC 152i waveguide was designed to work with Celestion drivers. Your measurements confirm it.
The main difference between the Celestion CDX1-1747 and the CDX1-1745 is in the suspension/damping of the diaphragm.
 
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I think I have a pair of horns like that, bought on close-out from Parts Express. I was going to use them the Peerless compression drivers, but never got around to it. Still sitting on a shelf somewhere. Nice to see measurements with other drivers.
 
The K510 or K402...
are on top of my wishlist (too)

I am seriously considering to build a clone, somewhat bigger than the 510.

A clue for the horizontals (the sidewalls), albeit undersized for the throat:
 

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The 510 and 402 are waveguides, primarily because of the high expansion rate.
The throat section has got very little, if anything, in common with OSWG's.
It's more akin to JBL's Image Control Waveguides, only......different.

However, I wouldn't be surprised to discover that JBL engineers were "inspired by Klipsch" during the development phase of their latest waveguides.
 
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It depends on the horn and the Phenolic driver, is this a Selenium or old JBL?

The phenolic one could be the Selenium D405. It can do 110dB 1W/1m at 500Hz slop at 12dB/oct, probably with 24dB/oct it can play at 300Hz

below the datasheet link in english

https://www.jblpro.com/ProductAttachments/D405_SpecSheet.pdf

I'm curious about the results, I never did this alignment but in theory it work and has high efficiency.

If I had bass reflex subs, I probably would try mid with phenolic and high with TI, it would save some power amp.
 
The phenolic one could be the Selenium D405. It can do 110dB 1W/1m at 500Hz slop at 12dB/oct, probably with 24dB/oct it can play at 300Hz

Search: "Bob Crites Cornscala".

Mid and HF drivers in this project are: JBL Selenium D405 and D220Ti.

With a -3 to -6dB slope towards the top-end, the D220Ti probably won't yell above the "smooth" midrange.
 
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With regards to the "smooth" midrange: provided you don't push the D405 too low.
500Hz seems already close to the limit and this will only work with a horn that's big enough.
The above applies under the assumption that the speakers will be used at home and not for PA.