Since compression drivers are high efficiency (although it should be lowered with HF compensation circuit I think), can I still install a simple attenuation circuit (if I find I need one) like the one here at the compression drivers terminals http://www.loudspeakers101.com/Lpad.htm

How should I decide how many db of HF attenuation to use in the circuit? I know it involves looking at the graph of the response of the compression driver on the horn, then summing the compensation circuit with it to get final response. So I think what I do is see how many db down at 20KHz it is, then pick the db attenuation values in the chart you sent me by email?

On the very last page of the file, it says "Note: Components R3, C4 and C5 are not used with woofers listed on this page. In all other respects, the 800aLxxdB crossover is the same as the standard 800a0xxdB 800Hz crossover, and the 1K6aLxxdB crossover is the same as the standard 1K6a0xxdB 1600Hz crossover." And the woofers listed are the JBL 2205H, 2226H and 2227H. Why are these components left out of the design with these woofers? I think though the file said this is only when using it as a pseudo first order filter. By the way, whats the difference between a pseudo first order and normal first order filters?

On the schematic, where it shows the symbol of the woofer, right behind it is the symbol for an inductor (the curely line) but no marking for it like L4 etc. I believe though that it is just part of the speaker symbol (because speakers themselves are kind of like inductors?).

Thanks! Adrian

Thomas

1. Attenuates the HF section to match the LF section
2. Augments the top octave to compensate for rolloff
3. Damps the peak at resonance

So to use a simple L-Pad will accomplish one of these things, but you'll still need to find solutions for the other two.

On some of my speaker designs, I use a midwoofer up to the point where it begins to rolloff. Most of these have some amount of series inductance, but it is used for response shaping rather than as a crossover. In that case, the Zobel is often omitted, and without it, the coil will not act as a first-order crossover. I call this arrangement a pseudo-first-order filter.

If you are planning to make an 800hz horn I would recommend the larger 1.750/1" flange. If you are planning on a smaller version similar to the 12" horn, then the 1.500/1" flange is better. If you decide to turn your own. you can use a 1" to 2" conical flange and that will give you a 2db gain. Yes, prices are USD. expensive but the best there are. shipping is included if you can wait for surface shipping. You can easily turn your own or if you know a friend who has a lathe perhaps you can buy him dinner. The dimensions on the site are all you need for correct angle format. The AT-3 is for 2" format and you dont want that.

The dimensions for the wood horns are whatever you want to make them.
The overall dimensions for the horns are on the website along with the flange dimensions. You'll have to reverse engineer it and make any changes to meet your own requirements. I would think the 800hz size to best suit your needs.

Bill

Also like to say thanks to everyone else who has responded to this post as well!

Adrian

Thanks! Adrian

If you decide to make the throat's from wood. I suggest using baltic birch plywood glued up to make 1.750 thickness. You will need the very thin laminates for flange strength. I believe making the flange itself 5/16 (8mm) thick will be good.

Bill