Does anyone have experience with the Harman Dbx 224xs?
It's affordable, curious how good they are?
It's affordable, curious how good they are?
For the particular case of 2.5 way WTW (or any multi-way symmetrical array) allpass filters work and are pretty simple to use if you have access to them in DSP software.
Found the article that explains it better:
Using All-Pass Filters | audioXpress
This is all a bit nitpicky though. The big picture is that is you have two woofers, you should probably be rolling one of them off before the tweeter XO.
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I would advise to also have a look at the PI3 and PI4 speakers from Wayne. They are high efficiency and use the DE250 with 12" and 15" PRO woofers...
I see the confusion.
DIYSG is not a business like Parts Express and isn’t run like one.
Long ago Erich spearheaded a group buy of two pallets worth of waveguides and horns from Autotech (out of Poland) and personally mailed out each order as well as eating the cost of the no-shows. When QSC stopped making their waveguide available to DIYers, effectively ending future Econowave projects, Erich once again stepped in and organized the crowdfunded SEOS project which resulted in the injection-molded SEOS-12 and SEOS-15 waveguides. The DNA-360 compression driver DIYSG uses on many of their designs is a bulk-purchased clone of the B&C DE250 with a few modifications that gives it slightly better performance for domestic applications. Many of the low-frequency drivers used in DIYSG designs are custom made for DIYSG by Eminence to application-specific specifications that are not featured on their generic off-the-shelf counterparts you’d see at the Parts Express website. The fusion series of kits at DIYSG were designed by DIY enthusiasts such as Bill Waslo and Jeff Bagby (RIP) who volunteered the designs without compensation because they wanted to help the community Erich was serving. Each order at DIYSG is hand packed by either Erich or his sister who helps him out. All of his kits ship for free, unless you’re ordering just drivers or flat packs.
The equivalent to the Fusion-15 is available from Parts Express. It uses the B-52 buyout waveguide with a throat entrance angle that is not matched to the DE-250 (inferior to the DNA-360). Adding the delta lite woofer makes the total about $25 USD more than ordering the Fusion-15 from Erich, does not include ports or a crossover schematic and will be packed nowhere near as well as it would be from Erich (his packing is without exaggeration the best I have ever seen). Unlike Parts Express, Erich will not take your money for products that he does not have on hand and has no idea when he will.
A lot of people are understandably perplexed why they can’t just order drivers and waveguides al a carte from the website but I assure you there’s a good reason why you can’t even if it isn’t readily apparent. DIYSG is not a day job for Erich, it is a hobby. It is his money in the endeavor.
"B-52 buyout waveguide with a throat entrance angle that is not matched to the DE-250"
Brinkman, do you have an angle measurement for the B-52 horn throat? I have a couple pairs of these horns in my shop and I like the way it sounds with the DE250. I would love to find a better fit if it's out there.
Or how do I measure the entry angle myself? It's a curve...
Brinkman, do you have an angle measurement for the B-52 horn throat? I have a couple pairs of these horns in my shop and I like the way it sounds with the DE250. I would love to find a better fit if it's out there.
Or how do I measure the entry angle myself? It's a curve...
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Take a known straight-sided object and insert it into the compression driver exit frustrum (this will require removing the bug screen). Using a small protractor, place it behind the protruding object and line it up so it passes through the origin on the protractor and extends to the graduated arc. The degrees past 90° it intercepts is a rough, unscientific measurement of the exit angle.
You can also use graph paper instead of a protractor and simply mark two points along the graph and dl the math.
You can also use graph paper instead of a protractor and simply mark two points along the graph and dl the math.
I want to know what the horn entry angle is too. I've seen a few specs for the DE250 as 12 and 14.6 degrees. How mismatched is the horn?
Earl Geddes quotes it as being 6.5°.
I shouldn’t have stated that they *are* mismatched when the the case is only that they *probably* are. The SEOS waveguides *were* designed to match the DNA-360, per Erich. Bill Waslo’s 3D printed unity horn was also designed to match the DNA-360 exit angle, per Bill.
At any rate, a degree or two of mismatch alone isn’t that big a deal. According the Earl Geddes, the issue is an unsmoothed transition from CD exit to horn throat AND the distance between this and the end of the phase plug. A longer distance allows HOMs to cut it at a lower frequency.
Sorry about the off-topic.
I shouldn’t have stated that they *are* mismatched when the the case is only that they *probably* are. The SEOS waveguides *were* designed to match the DNA-360, per Erich. Bill Waslo’s 3D printed unity horn was also designed to match the DNA-360 exit angle, per Bill.
At any rate, a degree or two of mismatch alone isn’t that big a deal. According the Earl Geddes, the issue is an unsmoothed transition from CD exit to horn throat AND the distance between this and the end of the phase plug. A longer distance allows HOMs to cut it at a lower frequency.
Sorry about the off-topic.
OK thanks. I guess if I cut the bug screen and put the driver on the horn I could stick my finger in there and feel the transition.
These parts we're talking about are my "pretty cheap and darn good enough" go-to for building PA style speakers and it's fun to try to squeeze out a bit more juice.
Speaking of staying on topic, I've never used the 12" Delta or Kappa Eminence drivers. The rising FR in the midrange looks jumpy and I've tried Faital PR300 instead which is pretty flat and smooth. Are the Eminence good to just shelf flat with DSP and reap the benefits of high sensitivity and low distortion, or are they actually underdamped there?
These parts we're talking about are my "pretty cheap and darn good enough" go-to for building PA style speakers and it's fun to try to squeeze out a bit more juice.
Speaking of staying on topic, I've never used the 12" Delta or Kappa Eminence drivers. The rising FR in the midrange looks jumpy and I've tried Faital PR300 instead which is pretty flat and smooth. Are the Eminence good to just shelf flat with DSP and reap the benefits of high sensitivity and low distortion, or are they actually underdamped there?
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Correct. Earl smooths this region out with modeling clay or something similar. Alternatively, you could fill this with Elmer’s woodfiller or for a non-hardening alternative, duct seal. I’ve heard of folks sanding down the filler after it hardened only to get little crumbs in the diaphragm chamber that messed the response.
I thought ill follow on from here as there was valuable information on this thread.
I have bought Deltalite 2515 B&C DE250 and the B52 horn. I am aware of the slight mismatch that tomuus mentioned on the DE250 and B52, which I think might not be such a big deal. I also know that the 2515 is going to beam before it reaches the decent lowest crossover point of the DE250. After some more prowling around in forums it seems that the best option is to find a compression driver that plays comfortably down to around 800hz or 900 hz tied in with a 15 inch although apparently many designs have had the 15 inch play up to the high 1800hz depending on the driver.
I just would like some help on how low can the DE250 play and the highest the 2515 can play without beaming. What is the ideal crossover of a PA speaker design with two drivers such as these? How bad do those low frequencies sound out from a compression driver?
I can purchase a better compression driver that plays significantly lower but then there is the problem of if it fits on the B52 and it matches. How do I go about finding this type of info out?
PS. I am going active crossover with software DSP.
I have bought Deltalite 2515 B&C DE250 and the B52 horn. I am aware of the slight mismatch that tomuus mentioned on the DE250 and B52, which I think might not be such a big deal. I also know that the 2515 is going to beam before it reaches the decent lowest crossover point of the DE250. After some more prowling around in forums it seems that the best option is to find a compression driver that plays comfortably down to around 800hz or 900 hz tied in with a 15 inch although apparently many designs have had the 15 inch play up to the high 1800hz depending on the driver.
I just would like some help on how low can the DE250 play and the highest the 2515 can play without beaming. What is the ideal crossover of a PA speaker design with two drivers such as these? How bad do those low frequencies sound out from a compression driver?
I can purchase a better compression driver that plays significantly lower but then there is the problem of if it fits on the B52 and it matches. How do I go about finding this type of info out?
PS. I am going active crossover with software DSP.
Maybe you should let the 15 beam a little to meet the horn. I'm going to guess maybe 1200Hz as a starting point. Going higher could be a problem for breakup of the woofer. Going lower could be an issue for the horn because of the small vertical dimension (the horn is the limit here, not the compression driver, and the horn normally determines how to cross).
The way to be sure is to do polars, including consolidating the asymmetry of the horn, and weighing up the tradeoffs of each way at the edge of their useable bandwidth.
The way to be sure is to do polars, including consolidating the asymmetry of the horn, and weighing up the tradeoffs of each way at the edge of their useable bandwidth.
Looks like letting it a beam a little is the only option. If I use digital crossovers with software DSP I can cross the woofer at 1000hz with a second order crossover let the rising frequency meet the compression driver which I'll low pass at a higher frequency around 1600hz and then the correction filter will EQ the gap.
But when using an active crossover I have one point and it's all about experimentation. I have read the horn is capable till 1000hz although the specs say till 600hz, I don't think that is true. So it seems that if the compression driver doesn't sound good crossed over that low my only option is to go with a better and larger compression driver.
Lastly, beaming is only a problem off axis(from my understanding) causing suck outs certain degrees off axis, so if I am in a small room and mostly sitting on axis and sometimes just off, then would the beaming still be an issue? This is for home use...
Still don't know how to take polars. Can this be done with REW?
But when using an active crossover I have one point and it's all about experimentation. I have read the horn is capable till 1000hz although the specs say till 600hz, I don't think that is true. So it seems that if the compression driver doesn't sound good crossed over that low my only option is to go with a better and larger compression driver.
Lastly, beaming is only a problem off axis(from my understanding) causing suck outs certain degrees off axis, so if I am in a small room and mostly sitting on axis and sometimes just off, then would the beaming still be an issue? This is for home use...
Still don't know how to take polars. Can this be done with REW?
If you do that, the result will be the same as each driver with its own filter plus this correction on each. There's no getting around that.
The DE250 can do 600Hz.
Don't you think beaming is a good thing (used properly)? Small rooms is where it makes the most difference.
Drivers purchased, front baffle CNC milled no turning back. I suppose the DIY nature keeps us going.
But like I said, I can always CNC a new baffle attach it on and chose a new compression driver with a better waveguide. For now, I will work with this.
Sorry for confusion, I meant the waveguide. But if you think the DE250 can play that low then that's great I thought I needed a larger compression driver with a better waveguide. Even if I can get down to 1200hz that should be good, just curious how the compression driver will play down that low. I suppose will see.
Mate, this is really important for me to get. Your sentence wasn't clear if you wouldn't mind confirming exactly what you meant regarding the beaming?
The waveguide is going to try to focus sound into a more narrow beam so that you can direct it away from the walls. I don't know what you know but sometimes when people get to talking about beaming, they cast a judgement on it rather than simply saying we want this much at this frequency.
Starting at low frequencies woofers tend to disperse wide, then higher up they conform to the baffle. At some higher frequency related to their size they go narrow before cone breakup sets in and you can't use them any higher.
Blending this with the waveguide for a smooth dispersion variation from low to high, makes sure the room reflections sound just like the direct sound. It's less distracting listening that way.
Starting at low frequencies woofers tend to disperse wide, then higher up they conform to the baffle. At some higher frequency related to their size they go narrow before cone breakup sets in and you can't use them any higher.
Blending this with the waveguide for a smooth dispersion variation from low to high, makes sure the room reflections sound just like the direct sound. It's less distracting listening that way.
Trdat - Generally you want the crossover frequency to be where the directivity of the cone driver and waveguide match up. For a cone driver you can approximate the directivity via the following formula: Directivity (in °) = 1,000,000/frequency/cone diameter.
So for a 15" driver the cone diameter is about 14.25". If you want 90° directivity you'll get that at about 800Hz. This is just approximate as cone geometry plays a role among other things, but it will get you into the ball park.
The B52 10"x14" waveguide is stretched a bit going down to 800Hz, but might be OK. Likewise your 15" driver might be OK moving up to 900Hz or even 1kHz. The DE250 should have no trouble in a domestic environment (not PA) going down to 800Hz with a steep-ish crossover (-24db/octave or more). If you want a shallower crossover move up the crossover frequency to 1kHz or more. Likewise you could look at any of the 1" CDs from Radian. They can probably support a 600Hz crossover in a domestic environment (but the B52 waveguide will no longer be working like a waveguide at that low frequency).
The main takeaway should be not to panic. Your design (15" midbass + B52 14x10 waveguide + 1"CD) will work just fine. Probably better than fine. If it were me I would go for a JBL 2226 and a Radian CD, but since you already have drivers I would stick with them to start and over time figure out what you want to improve. Please do let us know how things work out (and don't forget the pictures!!).
So for a 15" driver the cone diameter is about 14.25". If you want 90° directivity you'll get that at about 800Hz. This is just approximate as cone geometry plays a role among other things, but it will get you into the ball park.
The B52 10"x14" waveguide is stretched a bit going down to 800Hz, but might be OK. Likewise your 15" driver might be OK moving up to 900Hz or even 1kHz. The DE250 should have no trouble in a domestic environment (not PA) going down to 800Hz with a steep-ish crossover (-24db/octave or more). If you want a shallower crossover move up the crossover frequency to 1kHz or more. Likewise you could look at any of the 1" CDs from Radian. They can probably support a 600Hz crossover in a domestic environment (but the B52 waveguide will no longer be working like a waveguide at that low frequency).
The main takeaway should be not to panic. Your design (15" midbass + B52 14x10 waveguide + 1"CD) will work just fine. Probably better than fine. If it were me I would go for a JBL 2226 and a Radian CD, but since you already have drivers I would stick with them to start and over time figure out what you want to improve. Please do let us know how things work out (and don't forget the pictures!!).