After finishing my Fostex fe206n Karlsonator I am thinking about going two way for my second build. My technical knowledge is limited so I will need some help and opinions from more experienced builders to prevent me from building a Frankenstein.....
I want something vaguely resembling the JBL M2 Master Reference Monitor. After some research I have two initial drivers I like but I doubt is they overlap enought to be used in a two way system.
For the bass I was thinking about the Eminence Delta 15Lfa.
For the compression driver I like the B&C DE250-8 1" Polyimide Horn Driver.
Crossover point should be somewhere around 900hz. Is that at all possible?
As a comlete noob this might be a stupid question, but the response graphs of both drivers look to me as if they already cross over quite naturally (when i look at the response graph of the large vented enclosure recommended by Eminence). Could I get away with just a sharp low pass on the tweeter for protection purposes and run the Eminence without limitation?
Also, the compression driver seems to drop of sharply above roughly 16khz. Is it possible for an L-pad to tone down the tweeter below that frequency only and leave the response above 15 or 16k as is?
I want something vaguely resembling the JBL M2 Master Reference Monitor. After some research I have two initial drivers I like but I doubt is they overlap enought to be used in a two way system.
For the bass I was thinking about the Eminence Delta 15Lfa.
For the compression driver I like the B&C DE250-8 1" Polyimide Horn Driver.
Crossover point should be somewhere around 900hz. Is that at all possible?
As a comlete noob this might be a stupid question, but the response graphs of both drivers look to me as if they already cross over quite naturally (when i look at the response graph of the large vented enclosure recommended by Eminence). Could I get away with just a sharp low pass on the tweeter for protection purposes and run the Eminence without limitation?
Also, the compression driver seems to drop of sharply above roughly 16khz. Is it possible for an L-pad to tone down the tweeter below that frequency only and leave the response above 15 or 16k as is?
The Delta 15LF is not a good choice for a 2-way speaker. The LF stands for Low Frequency, it's a pure bass or sub driver. The B&C DE250 can't be crossed over that low either (B&C says 1,6kHz, I wouldn't a xo of lower as 1,2kHz even in a hifi setup), you'd need a lot bigger compression driver for that, probably 1,4" exit.
OK, I see I opened a can of worms here. I never heard of econowave but it seems quite a thing in the DIY community. But isn't the JBL M2 Master Reference Monitor just a very uneconomical econowave?
Maybe the Eminence 15"LFA is not the best choice. What would be a better 12" or 15" woofer to combine with the B&C de250. I plan on a vented design and will not use a subwoofer so it should go down to 40 or at least 45hz. For the box I am prepared to go up to about 150L max.
Maybe the Eminence 15"LFA is not the best choice. What would be a better 12" or 15" woofer to combine with the B&C de250. I plan on a vented design and will not use a subwoofer so it should go down to 40 or at least 45hz. For the box I am prepared to go up to about 150L max.
I used Sonido SCW300 and Eminence Deltalite II 2512 with DE250 in JBL PT waveguide and with 18sound XT1086 waveguide - xover at 1600Hz.
Eminence Deltalite II 2515, Acoustic Elegance TD15M, or Beyma SM115/N can work good with DE250 but you need very large horn/waveguide. Mine OSWG with lipover was about 50cm in diameter and it could be xovered acoustically at 900Hz easily. One must differentiate electrical xover from acoustical - in B&C datasheet electrical xover is mentioned. WG my friend made was based heavily on Gedlee's Summa WG with big lipover added.
Here's an old pic of the test boxes with Beyma 15K200 for woofers: http://s28.postimg.org/iqdb6fibh/wg_veliki.jpg
As for JBM M2 - it's so NOT uneconomical econowave.
It's woofer (designed by Jerry Moro) is one of the best i've seen in regard to distortion and frequency response. M2 WG is specially made for JBL D2430K double ring radiator and it's xover frequency with JBL 2216Nd is at 750Hz. Dr Aleksandar Voishvillo - russian engineer, now Sr. Manager Transducer Engineering & Acoustic Research at JBL, made JBL D2 ring radiator that enables such a low xover point, high power handling and low distortion.
So, JBL M2 is best of JBL reference monitors so far and worth every cent imo.
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im pretty sure any manufacturer would claim all their parts are specifically made for eachother 😉
i couldnt find the measurements right now but according to the lansing forum the 2450sl-be driver on the same waveguide requires half of the 20db EQ D2430k uses in the M2. (i would imagine off-axis are similar) so there must be some crash between the two?
Take a look at the AE td15s,x or h woofers for f3 mid 20s in room. And surf around for Faital 1.4" drivers and either the FAital tractrix horn or Eighteen sound 1.4" horn. Cross at 700hz for decent off access.
A bit pricy but it covers many bases. mid 20s to mid 10Ks at 94 db with good off access and high output. Hard to beat
A bit pricy but it covers many bases. mid 20s to mid 10Ks at 94 db with good off access and high output. Hard to beat
You're very welcome.
It's good woofer but asks for a really big cabinets. I sold them eventually and extra magnet fell of from one in the transport - so, was is bad build quality or mishandling during shipment, guess i'll never know.
Measurements of frequency response from the Sonido website are not entirely correct - but we've witnessed that with much more expensive drivers and large companies so that is somewhat expected.
I compared them with Deltalite II 2512. Both were very good.
You could be right. But then again, i haven't seen what happens in time domain or with distortion when 2450SL xovered that low. Maybe it's better than D2430K, maybe not. D2 has 2 voice coils that shares the load. Maybe they made D2 to match the WG - serious company like JBL hardly does WG to driver matching by trial and error.
The only way to be certain would be to buy both of the drivers and M2 wg, load the parameters into DSP and measure 🙂
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15"+horn 2 way is a classic design and has too many variations. The things that makes M2 standout from the rest are digital crossover, dual diaphragm driver and a huge and ugly waveguide.
I'm using 2450SL crossed at 650Hz. I uploaded the measurement here.
JBL DMS-1 Experience and Measurement
I remember that the measurement was done with 600Hz, but it is set to 650Hz (48dB linear phase) now. I don't think it can be crossed that low with 24dB filter with normal size wave guide.
If you ever change compression driver to D2, please measure them side by side in the M2 WG at say 95dB/100dB/105dB. It would be really interesting to see that measurements.
JBL drivers comparison was somewhere in large 4722 tread at AVSforum.
D2 current price is $650 https://reconingspeakers.com/product/jbl-d2430k-tweeter-for-jbl-m2-5032754x/
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I remember that D2 used to be less than half of that price... I guess D2 is not costly to manufacture.
Prices went up pretty fast for woofers and WG's also. M2 WG was about 200$ a piece. It is 375$ now. 2216 were about 400$ each, if i remember correctly.
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