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75.91.54.14
Finally got my ultimate 15" two-way speaker project together. It includes the Dayton Audio JBL clone horn with the PRV Audio D290Py-S 1" Polyimide Horn Driver 8 Ohms (DE250 clone)along with the JBL 2226 woofer. The cabinet is a JBL design from their mid seventies plans catalog. I opted to use the proven 4Pi crossovers from Wayne and I'm glad I did, they are just marvelous sounding. The sound is big, bold and powerful from low bass, smooth and silky highs all the way up to 20Khz. The PRV drivers need no equalization and are very dynamic. Now I just need an Emotiva XPA-2 amp to put some real power to them. Project turned out wonderfully, I'm tickled to death.
Edits: 05/15/15Follow Ups:
It's true that the acoustic center on a 15" two way is small and moving the test mic around will certainly easily display dips at or around the crossover point depending on the angle of the voice coil plain. With that in mind, its easy to position the speaker and listening position for most direct sound.
My friends, family and self have a ball listening to my 15" two way. The warts are there but no one seems to care. They to all types of music very well.
I tried using 2" horns down to below 600hz and they sounded great with one type of music and awful with another, just to hard to get them to cover the bases in a living room environment.
Smaller midbss with subwoofers can clean up the warts but really requires bi-amping (much more money) to do it right.
The naysayers have valid points But I for one have made an educated choice to ignore them in this case. The MXR 515s are in the living room for the foreseeable future.
Mr. Scholl,
Can you kindly post a pic of your speakers if possible?
I have been checking this forum at least twice a week, and reading interesting stuff. I am currently running Altec 612 cabs with either a 604-8G or a 416-8B(the latter, more bass dynamics) for the LF and just plain Altec 288C with original diaphragm/Azura AH-425. I am using mini DSP (3rd order LP and 4th order HP), a pentode strapped amp for LB and a 300B amp on HB. The room is 22x24 feet with 12 foot cathedral style ceiling. Listening position is about 12 feet away from the front wall and with the speakers about 11 feet away center center-to-center. I followed the Altec literature of "phasing" relationship with regards to the plane (distance of the VC) which can be checked by running some measurements with a mic and REW software. I like it very much.
In fact, I have no complaint and wondering why I am "liking" what I got. I listen to Jazz, 70's rock, Blues, 80's pop, etc. As for classical, I like it when I use pure analog(LP's only) more than with CD's as source using a belt drive table exclusively.
Am I just lucky?
Thanks,
Abe
If you search my name you should find a pic of the 12" two ways I built. The 15" two ways are just JBL MRX515 which I bought cheap localy.
I use vintage SS and old pro-sound SS. Cheap of course.
I use AE subs with the 12s.
I listen to a lot of the same music as you.
Thanks you!
Abe
Fantastic! Did the JBL cab plans you used specify mid/woofer to horn distance? I know Wayne's design and crossover are pretty persnickety about forward nulls. JH
I bought the cabinets already built. They were for a single JBL D130 and vent. I had to place the horn above a horizontal brace in the upper third of the cabinet. Maybe not ideal, but I think it worked out fine.
d
Edits: 07/06/15
A DIY 2 way w 15" woofers are the best bang for the buck in all of Audio. They are not perfect, but the combination of high efficiency and dynamics will make the majority of commercial offerings sound boring and un-engaging.
Even an electronic idiot like me can build one.
My 2-way: Altec 802 w an Altec 32 horn and Jensen P15LL.
2-way systems with smaller horns like this and 15" bass nearly always exhibit a large response dip near the crossover frequency. That can work well for some types of rock, but it's deficient for nearly everything else.
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Buy Chinese. Bury freedom.
"2-way systems with smaller horns like this and 15" bass nearly always exhibit a large response dip near the crossover frequency."
Ridiculous over en-composing statement.
Not perfect but no dip at my xover at 1500hz. There's enough efficiency that some adjustments can be accomplished in the network.
> Not perfect but no dip at my xover at 1500hz.
There's no dip, but that's on axis. Off-axis there will be with a fifteen crossed that high. Off-axis response is the issue with large drivers crossed over too high, not axial response.
It's difficult to interpret a graph with no legend, especially when the Y axis is zero everywhere. Are you really crossing a 15" woofer at 1.5kHz? Sorry, that's not hi-fi.
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Buy Chinese. Bury freedom.
"Are you really crossing a 15" woofer at 1.5kHz? Sorry, that's not hi-fi."
So all the later Altec 604 are junk?
"Are you really crossing a 15" woofer at 1.5kHz? Sorry, that's not hi-fi."
Allong with Tannoy DC's, an many others.
I guess I'm glad I'm not high-fi... it seems exhausting.
No dip that I can hear. See frequency response graph below. Millions of pro audio and studio monitors can't be wrong.
Edits: 05/16/15 05/16/15 05/16/15 05/16/15
I don't see a graph in your post. That aside, what we're discussing is a fundamental concept. The laws of physics haven't being changed to our benefit just because a manufacturer slaps a logo on a deficient design. Pushing a 15" woofer into the middle of the vocal range is musical ruination.
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Buy Chinese. Bury freedom.
Have you tried an aperture plate in front of the woofer?
Does that provide some compression loading or is there another effect?
No, it's just a diffraction slot (basic physics).
There was an article in the JAES many years ago, it's in the first speaker anthology.
Just curious...what kind of efficiency can you get in this configuration?
Here is a frequency response graph of Wayne's 4Pi speaker. I'm using the same crossover and woofer and nearly the same horn, driver and box. Should be pretty close..
speaker system efficiency will be set by the least efficient drive which in this case that will be the woofer. You can figure that your system efficiency will be a hand full of db greater than the driver efficiency due to room gain. There are many methods of calculating this, most bump the numbers up for marketing purposes. Most drivers show efficiency numbers calculated at mid range frequencies so again figure of 98 - 100 db will not reflect reality below 100 Hz where you really care. Hope this is of some use to you. Best regards Moray James.
moray james
Good for you. I too know the gratification of building a speaker system you really like. It brings to my mind that really old saying, If listening to music on your stereo is as much fun as going to the circus then listening to music played through speakers you built for yourself is as much fun as riding your own elephant to the circus.
Edits: 05/14/15
At the Lone Star Audio Fest several times. And Wayne is a great guy who seems to have loyal customers, for good reason.
My 15" 2-ways are an Altec 416 and a Heil AMT.
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