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My 15 inch two-way speaker project

168.8.170.2

Posted on May 14, 2015 at 18:14:23

Rpower
Audiophile

Posts: 280
Location: Northeast Georgia
Joined: October 27, 2000

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.

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RE: My 15 inch two-way speaker project

Scholl

05:58:29 05/17/15

RE: My 15 inch two-way speaker project

amandarae

21:22:58 05/17/15

RE: My 15 inch two-way speaker project

Scholl

16:23:16 05/18/15

...

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RE: My 15 inch two-way speaker project

Scholl

05:58:29 05/17/15

RE: My 15 inch two-way speaker project

amandarae

21:22:58 05/17/15

RE: My 15 inch two-way speaker project

Scholl

16:23:16 05/18/15

RE: My 15 inch two-way speaker project

amandarae

07:22:41 05/19/15

RE: My 15 inch two-way speaker project

hennfarm

02:46:23 05/17/15

RE: My 15 inch two-way speaker project

Rpower

03:15:56 05/17/15

RE: My 15 inch two-way speaker project

coli

20:35:43 05/15/15

best bang for the buck in all of Audio

lokie

06:27:23 05/15/15

Triode_Kingdom

11:00:07 05/15/15

lokie

19:30:46 05/15/15

Bill Fitzmaurice

14:36:39 05/16/15

Triode_Kingdom

21:59:29 05/15/15

djk

21:15:25 05/17/15

lokie

09:49:28 05/18/15

Rpower

08:02:49 05/16/15

Triode_Kingdom

08:24:40 05/18/15

djk

15:12:58 05/15/15

kyle

11:27:06 05/16/15

djk

21:11:59 05/17/15

RE: best bang for the buck in all of Audio

caffeinator

09:59:05 05/15/15

RE:Frequency response and efficiency of my two way

Rpower

08:29:52 05/16/15

RE: best bang for the buck in all of Audio

moray james

10:34:32 05/15/15

RE: My 15 inch two-way speaker project

Don Reid

19:43:50 05/14/15

Liked the PI Speakers I've heard

Sebrof

18:49:46 05/14/15

Liked the PI Speakers I've heard, posted on May 14, 2015 at 18:49:46
Sebrof Audiophile Posts: 634 Location: AusTX Joined: July 12, 2002	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.

RE: My 15 inch two-way speaker project, posted on May 14, 2015 at 19:43:50

Don Reid
Audiophile

Posts: 890
Location: Rural NW Georgia
Joined: February 2, 2001
Contributor
Since: April 1, 2010

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.
I dream of an America where a chicken can cross the road without having it's motives questioned.

best bang for the buck in all of Audio, posted on May 15, 2015 at 06:27:23
lokie Audiophile Posts: 1989 Location: Georgia, USA Joined: January 28, 2003	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.

RE: best bang for the buck in all of Audio, posted on May 15, 2015 at 09:59:05
caffeinator Audiophile Posts: 1729 Location: Pacific Northwest Joined: August 22, 2003	Just curious...what kind of efficiency can you get in this configuration?

RE: best bang for the buck in all of Audio, posted on May 15, 2015 at 10:34:32

moray james
Manufacturer

Posts: 1599
Location: Calgary on the Bow
Joined: May 19, 2002

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

Maybe not, posted on May 15, 2015 at 11:00:07
Triode_Kingdom Audiophile Posts: 10044 Location: Central Texas Joined: September 24, 2006	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.

RE: Maybe not, posted on May 15, 2015 at 15:12:58

djk
Manufacturer

Posts: 6135
Joined: June 17, 2000

Have you tried an aperture plate in front of the woofer?

RE: Maybe not, posted on May 15, 2015 at 19:30:46
lokie Audiophile Posts: 1989 Location: Georgia, USA Joined: January 28, 2003	"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.

RE: My 15 inch two-way speaker project, posted on May 15, 2015 at 20:35:43
coli	d

RE: Maybe not, posted on May 15, 2015 at 21:59:29
Triode_Kingdom Audiophile Posts: 10044 Location: Central Texas Joined: September 24, 2006	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.

RE: Maybe not, posted on May 16, 2015 at 08:02:49
Rpower Audiophile Posts: 280 Location: Northeast Georgia Joined: October 27, 2000	No dip that I can hear. See frequency response graph below. Millions of pro audio and studio monitors can't be wrong.

RE:Frequency response and efficiency of my two way, posted on May 16, 2015 at 08:29:52
Rpower Audiophile Posts: 280 Location: Northeast Georgia Joined: October 27, 2000	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..

RE: Maybe not, posted on May 16, 2015 at 11:27:06
kyle Audiophile Posts: 1839 Location: London Ontario Joined: September 29, 1999	Does that provide some compression loading or is there another effect?

RE: Maybe not, posted on May 16, 2015 at 14:36:39
Bill Fitzmaurice Industry Professional Posts: 5370 Location: New England Joined: October 20, 2002	>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.

RE: My 15 inch two-way speaker project, posted on May 17, 2015 at 02:46:23
hennfarm Audiophile Posts: 535 Location: Oregon Joined: October 8, 2008	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

RE: My 15 inch two-way speaker project, posted on May 17, 2015 at 03:15:56
Rpower Audiophile Posts: 280 Location: Northeast Georgia Joined: October 27, 2000	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.

RE: My 15 inch two-way speaker project, posted on May 17, 2015 at 05:58:29

Scholl
Distributor or Rep

Posts: 1357
Joined: March 8, 2001

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.

RE: Maybe not, posted on May 17, 2015 at 21:11:59
djk Manufacturer Posts: 6135 Joined: June 17, 2000	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.

RE: Maybe not, posted on May 17, 2015 at 21:15:25

djk
Manufacturer

Posts: 6135
Joined: June 17, 2000

"Are you really crossing a 15" woofer at 1.5kHz? Sorry, that's not hi-fi."

So all the later Altec 604 are junk?

http://stereonomono.blogspot.com/2012/08/altec-lansing-seven

RE: My 15 inch two-way speaker project, posted on May 17, 2015 at 21:22:58

amandarae
Audiophile

Posts: 2591
Location: So.Cal
Joined: November 30, 2004

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

RE: Maybe not, posted on May 18, 2015 at 08:24:40
Triode_Kingdom Audiophile Posts: 10044 Location: Central Texas Joined: September 24, 2006	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.

RE: Maybe not, posted on May 18, 2015 at 09:49:28
lokie Audiophile Posts: 1989 Location: Georgia, USA Joined: January 28, 2003	"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.

RE: My 15 inch two-way speaker project, posted on May 18, 2015 at 16:23:16
Scholl Distributor or Rep Posts: 1357 Joined: March 8, 2001	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.

RE: My 15 inch two-way speaker project, posted on May 19, 2015 at 07:22:41
amandarae Audiophile Posts: 2591 Location: So.Cal Joined: November 30, 2004	Thanks you! Abe

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