I didn't consider that at first because of just having one sub and because I assumed I would probably want a center and surrounds as well.
But now that you mention it, that would have made construction ten times easier. I had 32x49 MDF laying around in both 3/4 and 5/8. No matter what now I'll probably have to make a full tower version next time I pick up MDF.
I have more drawings up on my website.
NHT M3.3 Cabinet Drawings
If anyone has more and would like me to host them, drop me an email.
NHT M3.3 Cabinet Drawings
If anyone has more and would like me to host them, drop me an email.
First sounds
Finally was able to find the time to complete the first prototype speaker. This is a satellite portion of the 3.3 or 2.9 with some minor modifications using 3/4" MDF instead of 1" MDF.
I have the top two drivers off to the wrong side due to late night SNAFU, but the cabinet is only screwed together right now anyway. There were also a few other lessons learned regarding cabinet construction that, so that I will definitely just rebuild when I'm ready to do something more final.
There are a few options for the subwoofer. I have one NHT 1259 in a 3.5 ft^3 sealed enclosure (pretty much just followed the standard builds posted on the net for almost 20 years). I have a NHT SW2 that I used for my quick demo connected through the Carver PM1.5 you can see in the picture below. The other amp is an Elan 12 channel amp I scored on Ebay (70-90W/ch). Really neat for quick hookup and testing of active speaker designs when combined with the Behringer Ultradrive Pro. I used the published XO settings and have the upper two drivers wired out of phase with the 6.5" woofer and subwoofer (or did I misunderstand the wiring issue?).
The enclosure is not 100% sealed as it is only screwed together, but its pretty decent. There is no stuffing yet either.
Despite all of that, it's pretty good. I haven't taken any measurements and all amp and gain settings are at best ballpark. I can't wait to (a) build the real XO and (b) dial in the correct gain and amp settings using measurement data.
One remaining question is whether to keep the sat/sub configuration or attempt to build a full range 3.3 clone. Since I only have one 1259 woofer it won't be 100%, but I am interested in several options:
- 1 10" npt-11-083-2 subwoofer in 2.3 ft^3 sealed enclosure per side. This could allow the cabinet to be a little less deep
- 1 10" npt-11-125-1 subwoofer per side. Need to measure and see how similar to the VT-3 sub driver above this woofer is. Supposedly it is used in the NHT B10.
- Some combination of all 4 10" woofers listed above, thus making the bass section similar to the VT-3. THis would require (assuming the B10 subwoofer is similar enough) adding at least 1.5 ft^3 to the overall enclosure. A rough 48x8x35 (32 on the short side) gives a 20.5 degree front and about 5 ft^3 total volume.
- 1 Sunfire True 10" subwoofer. I just bought this bare driver really cheap and am mostly just curious. I have a line on a second one and maybe these could be used in very small sealed enclosures allowing the overall tower size to be reduced.
Questions:
- Is the front baffle fully integrated into the rest of the speaker design? Or could I change the angle to say 10 or 35 degrees with only the following impact:
-- The sweet spot for listening presumably is found by the tip of the isosceles triangle formed by the ASA (angle/side/angle) relationship of the two main speakers. At 10 degrees you'd want to have a very long room and at 35 degrees you'd be sitting closer to the speakers.
If those particular choices are too extreme, how about more modest changes between say 18 and 25 degrees?
- How critical is the 7.5" baffle width? Can that be made up to 10" without significantly changing the sound?
- Can the height placement of the upper section be changed somewhat freely with the understanding that it should correspond to the listeners head position ? Let's say +/- no more than 10 inches over the 3.3 schematics.
Finally was able to find the time to complete the first prototype speaker. This is a satellite portion of the 3.3 or 2.9 with some minor modifications using 3/4" MDF instead of 1" MDF.
I have the top two drivers off to the wrong side due to late night SNAFU, but the cabinet is only screwed together right now anyway. There were also a few other lessons learned regarding cabinet construction that, so that I will definitely just rebuild when I'm ready to do something more final.
There are a few options for the subwoofer. I have one NHT 1259 in a 3.5 ft^3 sealed enclosure (pretty much just followed the standard builds posted on the net for almost 20 years). I have a NHT SW2 that I used for my quick demo connected through the Carver PM1.5 you can see in the picture below. The other amp is an Elan 12 channel amp I scored on Ebay (70-90W/ch). Really neat for quick hookup and testing of active speaker designs when combined with the Behringer Ultradrive Pro. I used the published XO settings and have the upper two drivers wired out of phase with the 6.5" woofer and subwoofer (or did I misunderstand the wiring issue?).
The enclosure is not 100% sealed as it is only screwed together, but its pretty decent. There is no stuffing yet either.
Despite all of that, it's pretty good. I haven't taken any measurements and all amp and gain settings are at best ballpark. I can't wait to (a) build the real XO and (b) dial in the correct gain and amp settings using measurement data.
One remaining question is whether to keep the sat/sub configuration or attempt to build a full range 3.3 clone. Since I only have one 1259 woofer it won't be 100%, but I am interested in several options:
- 1 10" npt-11-083-2 subwoofer in 2.3 ft^3 sealed enclosure per side. This could allow the cabinet to be a little less deep
- 1 10" npt-11-125-1 subwoofer per side. Need to measure and see how similar to the VT-3 sub driver above this woofer is. Supposedly it is used in the NHT B10.
- Some combination of all 4 10" woofers listed above, thus making the bass section similar to the VT-3. THis would require (assuming the B10 subwoofer is similar enough) adding at least 1.5 ft^3 to the overall enclosure. A rough 48x8x35 (32 on the short side) gives a 20.5 degree front and about 5 ft^3 total volume.
- 1 Sunfire True 10" subwoofer. I just bought this bare driver really cheap and am mostly just curious. I have a line on a second one and maybe these could be used in very small sealed enclosures allowing the overall tower size to be reduced.
Questions:
- Is the front baffle fully integrated into the rest of the speaker design? Or could I change the angle to say 10 or 35 degrees with only the following impact:
-- The sweet spot for listening presumably is found by the tip of the isosceles triangle formed by the ASA (angle/side/angle) relationship of the two main speakers. At 10 degrees you'd want to have a very long room and at 35 degrees you'd be sitting closer to the speakers.
If those particular choices are too extreme, how about more modest changes between say 18 and 25 degrees?
- How critical is the 7.5" baffle width? Can that be made up to 10" without significantly changing the sound?
- Can the height placement of the upper section be changed somewhat freely with the understanding that it should correspond to the listeners head position ? Let's say +/- no more than 10 inches over the 3.3 schematics.
Attachments
The baffle width is critical- there's some interesting subtlety to how they avoid the baffle step. Likewise, you'll want to use the original height- the interaction with the floor was taken into account, no "Allison dip" in any of my REW measurements. Use an open cell polyurethane foam strip on the outside edge- it makes a difference.
Thanks Sy,
I wasn't aware the baffle width had that big of an impact. Likewise I never thought about floor interactions. I agree about the foam strip, but it's not necessary yet at this stage. I will have to dig up the e-mail from NHT suggesting where to buy the right kind of material (assuming it's the same used on the VT-2 and other speakers).
I wasn't aware the baffle width had that big of an impact. Likewise I never thought about floor interactions. I agree about the foam strip, but it's not necessary yet at this stage. I will have to dig up the e-mail from NHT suggesting where to buy the right kind of material (assuming it's the same used on the VT-2 and other speakers).
That would be helpful- mine were pretty chewed from the get-go and my ex-wife's cats finished the job. Fortunately, I had some skived open-cell PUR foam in my junk-box which worked very nicely, but that's not an option for other cloners.
The other advantage you get from maintaining the front panel angle is that it reduces a notch in the midrange from the reflections off the back panel coming back through the cone.
The other advantage you get from maintaining the front panel angle is that it reduces a notch in the midrange from the reflections off the back panel coming back through the cone.
How close is that tweeter to the original?
Did you compare the DC resistance?
I have a pair of the original tweeters but they are the
chambered version - they were on sale when I got them.
I figure I can just plug the pole vent and check the Fs to
see if it is in the ball park of the original.
Those NHT 10" woofers are very inefficient from what I remember of
the numbers. I'd go with pairs, but even so, I think that there are
some auto sound 12" drivers that are close enough and under $100
each. I wouldn't be surprised if they are better than the 1259.
There's probably a parts express Dayton reference that would work
well, would have to check the numbers, but these are not cheap:
Dayton Audio RSS315HF-4 12" Reference HF Subwoofer 4 Ohm High Fidelity Reference Series 295-464
This looks closer based on cone mass and Fs, Qs are low but that allows
for higher DCR in the crossover inductor - one could ignore or use the
servo feature:
SW-12-04
Did you compare the DC resistance?
I have a pair of the original tweeters but they are the
chambered version - they were on sale when I got them.
I figure I can just plug the pole vent and check the Fs to
see if it is in the ball park of the original.
Those NHT 10" woofers are very inefficient from what I remember of
the numbers. I'd go with pairs, but even so, I think that there are
some auto sound 12" drivers that are close enough and under $100
each. I wouldn't be surprised if they are better than the 1259.
There's probably a parts express Dayton reference that would work
well, would have to check the numbers, but these are not cheap:
Dayton Audio RSS315HF-4 12" Reference HF Subwoofer 4 Ohm High Fidelity Reference Series 295-464
This looks closer based on cone mass and Fs, Qs are low but that allows
for higher DCR in the crossover inductor - one could ignore or use the
servo feature:
SW-12-04
Just give me you P.M and I will send you pics ( step by step ) of the construction of the 2.9Howdy y'all,
I'm a little late to the party, but am finally getting around to unpacking the big box of drivers I bought around 2007 from somebody on the East Coast selling on eBay dirt cheap.
Recently I found all the NHT sale threads and Jack Hindley's spreadsheet, so I don't know whether I got lucky and part of the sale or what, but it seems I have the following laying around:
- 10 6.5" Foster woofers from the 3.3 and 2.9
- 10 4 inch shielded drivers, appear to be from AC2 and thus the same as in the 3.3 and 2.9
- 5 tweeters I thought were Superseries tweeters, but they look like the tweeter in my AC1 and have a sticker on the back that reads "050/1 2101 NORWAY".
- 1 NHT 1259 is in the mail right now, and I have 2 new 10 inch NHT woofers (might be VT-2 replacements, but the number is not-11-125-1 so it doesn't match Jack's spreadsheet)
I would like to build myself a 3.3 clone. Since NHT 1259s are a little, umm, "hard to find" and I only have 1, I was thinking of trying to make it more of a 3.3 sat with a single 1259 sub or maybe using the other 10 inch woofers if I can find out a little more about them.
I've seen the VR-3 threads and found the plans for them as well as a (partial?) cabinet drawing for the 3.3 and a XO schematic. I was planning to use a Behringer active XO, because I am a little out of my swimlane when it comes to electronics at the moment.
Has anybody else made a 3.3 or 2.9 mid/high sat and have any advice to offer?
Is there a 2nd page to the 3.3 cabinet schematic? There are references to detail drawings and the various measurements don't all add up (overall height is 48 inches, but I added it up to be 48.883). To be fair, reading schematics isn't my day job and I could be way wrong here. Do the two mid range woofers have separate chambers or share one open volume space (this may be a dumb question to a seasoned speaker builder, sorry if it is)?
If I build the sat/sub config, is the 21 degree angle on the front no longer relevant as long as I simply point the sats at the listening position using the correct angle?
And while helping out could also be offers to take the drivers off my hands and help me clean out my garage, I will have to ever so graciously decline ...
Sorry been away for a while, but stumbled into a great find the day I came back home. Knocked $100 off the asking price because one of the 6.5 inch woofers was silent, but I have spares and figured based on Sy's and Jack's comments it was likely in the crossover anyway. I've been waiting so long to get a pair, I wasn't going to let that stop me.
Sy, I know you'll recognize this picture in your sleep ... just wish I hadn't spent 45 minutes trying to get the 12 inch woofer out before wondering "how did Sy do that?" and re-reading your pages.
A 100uF, 50V capacitor from Radio Shack is connected in there temporarily until I can reach the NHT support folks (hopefully they still have some old stock parts) or someone else can point me to where I can find a 92.5 uF NP electrolytic capacitor. Bottom line though: The lower-mid is again functional!!! All I can say is thanks Jack and Ken and the rest of the team that created these beasts - unbelievable! I had no idea. I've never heard anything even remotely close to this good - and I don't mean to be knocking the two pairs of VT-2 speakers I own. Even with one dead low-mid woofer it was clear I had entered a new realm of sound quality.
I will still continue with the cloning project, but am finding out rather quickly that sourcing the XO components is only slightly harder than getting Mr Spock to be emotional ... or at least I'm obviously looking in all the wrong places. The only places I know to look at Mouser and Digikey and as a relative newby in electronic circuits I can't say for sure I'm right, but it seems like they don't carry even one single component that matches the 3.3 crossover spec sheet. I must be missing something here, but I have no idea. I might have to settle for an active XO approach in the end.
Sy, I know you'll recognize this picture in your sleep ... just wish I hadn't spent 45 minutes trying to get the 12 inch woofer out before wondering "how did Sy do that?" and re-reading your pages.
A 100uF, 50V capacitor from Radio Shack is connected in there temporarily until I can reach the NHT support folks (hopefully they still have some old stock parts) or someone else can point me to where I can find a 92.5 uF NP electrolytic capacitor. Bottom line though: The lower-mid is again functional!!! All I can say is thanks Jack and Ken and the rest of the team that created these beasts - unbelievable! I had no idea. I've never heard anything even remotely close to this good - and I don't mean to be knocking the two pairs of VT-2 speakers I own. Even with one dead low-mid woofer it was clear I had entered a new realm of sound quality.
I will still continue with the cloning project, but am finding out rather quickly that sourcing the XO components is only slightly harder than getting Mr Spock to be emotional ... or at least I'm obviously looking in all the wrong places. The only places I know to look at Mouser and Digikey and as a relative newby in electronic circuits I can't say for sure I'm right, but it seems like they don't carry even one single component that matches the 3.3 crossover spec sheet. I must be missing something here, but I have no idea. I might have to settle for an active XO approach in the end.
Attachments
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WOW! Awesome!!!
Is that a wood veneer or did you use solid wood construction? It looks fantastic.
You can build it up out of smaller values- it will help to have a capacitance meter since electrolytic tolerances are, ummmm, generous.
These are truly great speakers, even before the mods. When I first got mine fired up, I spent a few hours playing with the setup and got them singing- it really is worth the time to really get all the distances and angles locked in. The dynamics and the precision of image and soundstage are what really hooked me.
Thanks! Yes this is wood veneer. As I said, I'm up for cloning the 3.3 ( got all the original drivers and Xovers bought on Ebay ) However the cabinet drawing on SY site confuses me quite a bit. I can see on this pic that the side or part of it has a backer board just as well... Is it a 3/4 or 1 inch thick ? Same dimension of the one the one in the back ( 13.5 x 13.5 ) ? The separator boards should'nt the be 5 inch wide instead 7. Do both of these separators have 3 openings ? Would be very grateful if you could provide me with these informations ( while your cabinet is still opened ). Finally I replaced all my NP electrolytic capacitors and agree with SY have a capacitance meter handy when buying them. Yes their tolerances may sometimes exceed 10%...
You should use non-polar electrolytics or back to back polarized types of twice the value.
XO inductors from these sources:
Inductors for Speakers from Madisound
Crossover Inductors in the Speaker Components Department at Parts Express | 296
DIY Speaker Components | Replacement Speakers | and Speaker kits from Meniscus Audio Group
Those look like steel laminate from the inductors that I can see in your picture, try to use same type of same gauge.
These are probably heavier gauge than you need:
http://www.madisound.com/manufacturers/madisound/inductors/sledgehammer.php
Meniscus will custom wind and I don't think they charge much more than stock values.
Any updates, you were doing a nice job and I'd disagree that the baffle width is so critical.
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I got 2 1259 subs during the sale but later got 4 (actually bought 6) DV12 (2 for a friend) from Audio Concepts. This must have been around 1993-94-95.
I found the DV12s better than the 1259 at least for my room.
if you are not including the 21 deg angle make sure you increase the depth to compensate. I believe Ken Kantor is still around and maybe still lurks on diyaudio maybe you can email him.
Ken Kantor about
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