Waveguides - 1" bolt on driver and commercially available?

[John Sheerin]

Hey guys,
A friend of mine is wanting to build 2-way PA boxes for DJ'ing. I'm looking to steer him towards a design similar to Geddes' Summa. I would take measurements and help him design the crossover. He already wants to use a 15" woofer and 1" exit compression driver. However I can't find any commercially available waveguides or non-diffraction horns of the right size (12" diameter or bigger) that take a 1" bolt on driver (as opposed to thread on). If it was my own project I'd build my own, but I don't want to get involved with yet another project for someone else - too many of my own. Does anyone have any suggestions?

Or should I just tell him to go with a threaded driver?

Thanks,
John

[MunkeyQ]

Try to steer him away from using a 15" woofer with only a 1" comp - most woofers that big have trouble getting up high enough cleanly to meet the 1". You end up with a nice big hole in the response, right in the vocal range. Directivity at that frequency would be pretty awful too.

If he's dead set on having a 15" woofer, I'd suggest a 2" compression driver on a big flare to get the loading down to 1-1.5khz, at the expense of a bit of HF response. Does he use subwoofers? If so, definitely go for a 12" or 10" with a 1" comp, tuned higher. A smaller woofer is lighter too, so it's easier for him to lift them up onto their tripods or whatever he's using.

[John Sheerin]

I'm trying to get a big waveguide to match the directivity of the 15" at the crossover.

[MunkeyQ]

I'd be more concerned about how a 1" comp is going to have great difficulty playing low enough to meet a 15" woofer. It might be achievable in a hi-fi design where the power handling requirements are far less, but for DJ stuff, you really can't force a 1" that low without some EQ on the woofer...or a woofer that plays exceptionally high.

[John Sheerin]

Yeah, I'd be crossing at about 1500Hz which is about what most of the compression drivers I'm looking at are rated for. I'm looking at a B&C 15NDL76 for the woofer.

How about the 18sound xt1086. This looks like it controls directivity well down to 2kHz and then starts to broaden. Found a source online - this is what I'm recommending to him. I should have just searched a little more...

[doug20]

AEspeakers TD15M and 18SOUND XT1086/B&C DE250 would a good choice!! Although I would go with the TD12M instead to get an easier XO.

Out of all the drivers I have found the TD series has the best higher frequency response patterns.

[doug20]

Originally Posted by MunkeyQ

Try to steer him away from using a 15" woofer with only a 1" comp - most woofers that big have trouble getting up high enough cleanly to meet the 1". You end up with a nice big hole in the response, right in the vocal range. Directivity at that frequency would be pretty awful too.

If he's dead set on having a 15" woofer, I'd suggest a 2" compression driver on a big flare to get the loading down to 1-1.5khz, at the expense of a bit of HF response. Does he use subwoofers? If so, definitely go for a 12" or 10" with a 1" comp, tuned higher. A smaller woofer is lighter too, so it's easier for him to lift them up onto their tripods or whatever he's using.

Many 2-way designs have 1" CDs and XOs down near 1KHz so Im not sure what you are posting. Geddes Summa XO below 1KHz and its a 15" + 1" CD (B&C DE250)

2" CDs go down below 700Hz and have limited control above 10KHz, no reason to use them if the XO is 1KHz. 1" CDs are fine down to that point if you can find a waveguide that keeps the directivity down that low (The QSC HPR152i did that).

AVS DIY forum had a new prototype designed recently, its a SEOS-15 and it will work very well down to 1KHz with the BMS4550 (see the waveguide group buy thread on this topic). The prototype has not reach the US so final measurements, final price has not happened. We are trying to make a product that is as good as or better then Geddes 15" OS designs and cost much, much less for everyone to buy.


If this is a pro audio build then the OP should go active with the DCX giving him great advantages like steep slopes and proper delay settings.

[seanny]

QSC no longer sell the HPR models, so they stopped selling those waveguides to diy. Their new models still use 1" CD, even with 15" woofer, but now switch to axisymmetric waveguides. My guess is that they still use screw on CD.

QSC can make any shape waveguides they want, yet choose axisymmetric. For diy, is it worth yearning for SEOS waveguide?

[MunkeyQ]

Originally Posted by doug20

Many 2-way designs have 1" CDs and XOs down near 1KHz so Im not sure what you are posting. Geddes Summa XO below 1KHz and its a 15" + 1" CD (B&C DE250)

Correct me if I'm wrong, but I've got a feeling that the power handling with a crossover at 1khz is compromised - fine for hi-fi, but I've seen quite a few compression drivers blown when crossed over so low in pro applications. Do Geddes do any fiddling with the woofer's response out of interest?

Hmm...I guess in the US it's a bit different as I've just received a pair of 152i waveguides and a 122i to complete a project last week. Shame really, great things for the price although they're bolt-on, and the 122i's bolting method is nonstandard to say the least. Has anyone tried the KW series waveguides out of interest?

The 152i uses EQ on the woofer as far as I know. I have a couple of Celestion CDX1-1745 drivers in my current hi-fi build, as used in the 152i. They really don't sound great crossed over below 1.5khz IMO, even on the 152i's waveguide which should offer loading down that low. It's even worse on the shorter 122i conical...

I'm personally also not a fan of big woofers in DJ cabinets as it makes it difficult for one person to lift them up high to plonk on a table or tripod. Unless you use neo of course.

[doug20]

Originally Posted by MunkeyQ

Correct me if I'm wrong, but I've got a feeling that the power handling with a crossover at 1khz is compromised - fine for hi-fi, but I've seen quite a few compression drivers blown when crossed over so low in pro applications. Do Geddes do any fiddling with the woofer's response out of interest?

Sure anyone can blow CD if they do not control it properly. I have no idea about the OPs SPL levels so I can not assume what will or won't happen. I just know that 1" CDs do work down to 1KHz.

What do you mean by fiddling? 15" woofers can play nicely up to 1KHz, the XO point is where the beaming is starting to occur and it should match the directivity of the waveguide.

Hmm...I guess in the US it's a bit different as I've just received a pair of 152i waveguides and a 122i to complete a project last week. Shame really, great things for the price although they're bolt-on, and the 122i's bolting method is nonstandard to say the least. Has anyone tried the KW series waveguides out of interest?

The 152i uses EQ on the woofer as far as I know. I have a couple of Celestion CDX1-1745 drivers in my current hi-fi build, as used in the 152i. They really don't sound great crossed over below 1.5khz IMO, even on the 152i's waveguide which should offer loading down that low. It's even worse on the shorter 122i conical...

The Celestion CDs do not play nice below 1.5Khz, I own both the 1745 and 1425. The 1425 does not even play very well below 2KHz.

I have the 152i waveguides. I used the BMS4550, Radian 745 and Im going to get the DE250. So far the BMS4550 is the best sounding one for me.

Never tried the KW series.