I've written up some (I think) worthwhile modifications to the NHT 3.3. If anyone is thinking about cloning them, there's enough info there for you to do so.
http://syclotron.com/?page_id=9
After I get back from camping this weekend, I'll see how many mistakes people found.😀
I'm pretty happy with this setup.
http://syclotron.com/?page_id=9
After I get back from camping this weekend, I'll see how many mistakes people found.😀
I'm pretty happy with this setup.
Those were good speakers. I remember repairing a set from a recording studio that had the crossovers fried.
Apparently, it's almost impossible to kill the drivers. The ones I got had some crossover capacitors spectacularly exploded. It took about 15 minutes to get them singing.
Did you consider an LT to improve the bass extension? The peaked filter provides some subsonic filtering of course.
Oh, I'd say that you can kill them if you try hard enough.
I don't think that tweeter has tinsel lead in wires. At least higher order crossover networks are used.
Which caps exploded, just curious?
Pete B.
Oh, I'd say that you can kill them if you try hard enough.
I don't think that tweeter has tinsel lead in wires. At least higher order crossover networks are used.
Which caps exploded, just curious?
Pete B.
An LT is a good alternative. But it won't be very different- flat is flat. At an f3 of 18Hz, the extension is pretty good.😀
To show how truly sick I am, I'm currently running the 1259s to 32Hz, 4th order Linkwitz-Riley high pass, then crossing over to a pair of eq'd JBL 2245H in 10 cu ft cabinets. A pair of 500W Sunfire mono amps run the JBLs, with the 1259s powered by a stereo 250Wpc Sunfire.
Dynamic range is not a problem.
edit: The blown cap in all four speakers was C2, but one speaker had a bad C3.
To show how truly sick I am, I'm currently running the 1259s to 32Hz, 4th order Linkwitz-Riley high pass, then crossing over to a pair of eq'd JBL 2245H in 10 cu ft cabinets. A pair of 500W Sunfire mono amps run the JBLs, with the 1259s powered by a stereo 250Wpc Sunfire.
Dynamic range is not a problem.
edit: The blown cap in all four speakers was C2, but one speaker had a bad C3.
Do you have those JBLs in vented cabinets? Where are they tuned if so?
These are 1259s, 2 on each side, and they are vented:
http://members.aol.com/basconsultants/spkrs.jpg
Pete B.
These are 1259s, 2 on each side, and they are vented:
http://members.aol.com/basconsultants/spkrs.jpg
Pete B.
Sealed and equalized flat to about 14-15 Hz. Without eq, it's close to a Bessel at an fc of about 55 Hz.
They had four, now I have four. 😀
They still do have the upper bass and midrange drivers at ACS, I think Madisound has the 1259,and I have the drawings for the cabinets. Just in case you're a good woodworker and are ambitious.
They still do have the upper bass and midrange drivers at ACS, I think Madisound has the 1259,and I have the drawings for the cabinets. Just in case you're a good woodworker and are ambitious.
Do you happen to know if the tweeters have rear chambers or not? I have the chambered version of that tweeter and the 1259s. I would like to see the plans for the cabinet, what's the best way, email or download?
Pete B.
Pete B.
I'll check with Jack Hidley and see if he has the pdfs. If so, I'll post them at my site. If not, I'll scan the hard copies that I have.
The tweeter doesn't have a back chamber, but does have ferrofluid. It's a stone-stock SEAS H534 (25TAF/D). Of all the drivers, it's the easiest one to substitute.
The tweeter doesn't have a back chamber, but does have ferrofluid. It's a stone-stock SEAS H534 (25TAF/D). Of all the drivers, it's the easiest one to substitute.
Looks like Madisound has the replacement domes for the tweeters also.
Noticed the large (71 uF) series cap on the SEAS midrange which suggests a low crossover point. Specs call out 320 Hz which is rather low for a small driver with a 1" voice coil. I'd expect some thermal compression there. Will also result in more IM distortion. Curious as to why they didn't choose a higher XO.
Pete B.
Noticed the large (71 uF) series cap on the SEAS midrange which suggests a low crossover point. Specs call out 320 Hz which is rather low for a small driver with a 1" voice coil. I'd expect some thermal compression there. Will also result in more IM distortion. Curious as to why they didn't choose a higher XO.
Pete B.
The Stereophile review I linked to shows the crossover to the mid; it is indeed about 300Hz. But it's fairly steep and as a practical matter, I've been playing these speakers quite loud, but the midrange stays remarkably clean.
Looks, in Figure 3, as if it starts off at 12 dB/Oct then 24 below 200 Hz. Seems to be 3dB down at the crossover, LR4 should be 6, probably, roughly a B3?
Figure 2 does seem to show that the lower mid needs about 2 dB more output. JA states that he made the "anechoic" measurement below 300 Hz using nearfield measurements. Ah, probably as shown in Fig 3. Interesting, that the driver outputs all hit the 0 dB mark in Fig 3, whereas the vector sum in Fig 2 suggests that there is some phase error shown as reduced output in the lower bass passband. I understand that your crossover mod provides a correction for this issue.
The lower mid has a narrow passband, and could certainly be taken up to 500 or 700 Hz, wonder how 300 Hz was chosen.
Pete B.
Figure 2 does seem to show that the lower mid needs about 2 dB more output. JA states that he made the "anechoic" measurement below 300 Hz using nearfield measurements. Ah, probably as shown in Fig 3. Interesting, that the driver outputs all hit the 0 dB mark in Fig 3, whereas the vector sum in Fig 2 suggests that there is some phase error shown as reduced output in the lower bass passband. I understand that your crossover mod provides a correction for this issue.
The lower mid has a narrow passband, and could certainly be taken up to 500 or 700 Hz, wonder how 300 Hz was chosen.
Pete B.
I don't know for sure, but I can guess. The Foster driver seems to have some breakup at 1k or so (there's a wiggle in the impedance curve right about there), and perhaps extending its range makes this audible. And there could perhaps be some advantage in coherency to letting a single driver handle as much of the midrange as possible.
1K breakup? That's low and unfortunate.
Do you plan to do any in room response testing, perhaps with SynRTA? Curious to see how the rear boundary loaded woofer does.
Pete B.
Do you plan to do any in room response testing, perhaps with SynRTA? Curious to see how the rear boundary loaded woofer does.
Pete B.
The frequency response curve I showed was in-room, two speakers going, taken from the listening position. The rear boundary kinda gives up at 40 Hz as the wallboard starts to flex, and I get a neat 3dB shelf.
http://syclotron.com/?page_id=27 near the bottom of the page.
http://syclotron.com/?page_id=27 near the bottom of the page.
I did see that one previously, but I was curious also about the rest of the response above 200 Hz. That is above the woofer crossover but was curious anyway.
That is interesting, looks like you're losing 5 or 6 dB, that would be one boundary, not full loss. Is the floor concrete or regular flooring?
And this has your bass boost filter, so a normal 3.3 would have 10 dB more attenuation at 20 Hz, if I'm following correctly.
That is interesting, looks like you're losing 5 or 6 dB, that would be one boundary, not full loss. Is the floor concrete or regular flooring?
And this has your bass boost filter, so a normal 3.3 would have 10 dB more attenuation at 20 Hz, if I'm following correctly.
Seems it would be to their advantage to provide the 3.3 enclosure drawings, for builders who use the MAD1259 and their surplus drivers.
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