dudaindc said:This is the same person that recently sold (and is still selling) some XdW units.
I noticed that the seller has some other NHT items like the M20s.
I have to believe SOMEONE bought the remaining inventory of completed products. It makes no sense to throw away high value items; both financially and ethically. NHT was not successful because they tossed money out the window , and their blog indicates they do not wish to waste resources. The only reason I can see why the site stopped making this stuff available to US(diy'ers) was that some current or potential dealers(when NHT restarts) objected to them not having first dibbs Afterall , many still have NHT inventory and the public being able to buy these products below dealer cost did not sit well. I think we will see this stuff become available in the near future; just not at give away prices. Just my 2 cents
I believe that NHT does have grilles for the XdS speakers available, but you will have to contact them.
Making a grille yourself is going to be very difficult, since the XdS grille was bent out of thin wire and welded together. I've attached a rendering of the design. The dimensions for the location of the four locating pins are:
Wire diameter 3.7mm
Vertical spacing 97.4mm
Horizontal spacing 116mm
Making a grille yourself is going to be very difficult, since the XdS grille was bent out of thin wire and welded together. I've attached a rendering of the design. The dimensions for the location of the four locating pins are:
Wire diameter 3.7mm
Vertical spacing 97.4mm
Horizontal spacing 116mm
Attachments
Thanks Jack - I will follow your advice. (In the meantime I will have razor wire around my speakers.
Danny,
The spectral tilt is visible in the WF-100k measurements on the sale site. It is around 6dB/octave. A sealed box rolls off at a rate of 12dB/ocatve. So the short answer is no, it won't work to eq your sealed box with an Fcb of 60Hz.
The longer answer is this. If you also adjust the Q of the HP filter around 30Hz, you can probably get a fairly flat alignment of box+driver+shelving filter+HP filter. How well this works will be a function of the Qcb of the driver+box. A lower Qcb will make it easier. You will really need to put all of these elements into some speaker modeling software to see how good you can make it. Most of the shareware/freeware won't model the spectral tilt/shelving filter, so you will have to model everything else and then design the system for a drooping response (of 1.5-6dB/octave), so that you can adjust the tilt control on the amplifier to make the entire system flat.
The spectral tilt is visible in the WF-100k measurements on the sale site. It is around 6dB/octave. A sealed box rolls off at a rate of 12dB/ocatve. So the short answer is no, it won't work to eq your sealed box with an Fcb of 60Hz.
The longer answer is this. If you also adjust the Q of the HP filter around 30Hz, you can probably get a fairly flat alignment of box+driver+shelving filter+HP filter. How well this works will be a function of the Qcb of the driver+box. A lower Qcb will make it easier. You will really need to put all of these elements into some speaker modeling software to see how good you can make it. Most of the shareware/freeware won't model the spectral tilt/shelving filter, so you will have to model everything else and then design the system for a drooping response (of 1.5-6dB/octave), so that you can adjust the tilt control on the amplifier to make the entire system flat.
Modeling the npt-11-081-1 drivers
NHT specifies for their speaker model VS-2.4 (-3 dB at 60 hz).
http://nhthifi.com/current/products/vintage/vs-24.html
This speaker uses a pair of the 5.25" npt-11-081-1 drivers.
However, when I model a pair of these drivers in a sealed enclosure using Bass Box Pro, the lowest -3 dB point I can get is around 87.5 hz. This is with box ID 16" x 5.75" x 8.5"
I am using these parameters:
Fs 56.3 hz
Qms 3.023
Vas 7.23 (14.46 net) liters
Cms 0.637 (0.319 net) mmN
Mms 12.6 (25.2 net) gm
Xmax 4.5 mm
Sd 89.9 (179.8 net) sq cm
Qes 0.665
Re 5.93 (2.965 net) Ohms
Z 32.9 (16.45 net) Ohms
Qts 0.545
NHT specifies for their speaker model VS-2.4 (-3 dB at 60 hz).
http://nhthifi.com/current/products/vintage/vs-24.html
This speaker uses a pair of the 5.25" npt-11-081-1 drivers.
However, when I model a pair of these drivers in a sealed enclosure using Bass Box Pro, the lowest -3 dB point I can get is around 87.5 hz. This is with box ID 16" x 5.75" x 8.5"
I am using these parameters:
Fs 56.3 hz
Qms 3.023
Vas 7.23 (14.46 net) liters
Cms 0.637 (0.319 net) mmN
Mms 12.6 (25.2 net) gm
Xmax 4.5 mm
Sd 89.9 (179.8 net) sq cm
Qes 0.665
Re 5.93 (2.965 net) Ohms
Z 32.9 (16.45 net) Ohms
Qts 0.545
There are a couple of things that aren't not being modeled that affect the f3.
1) The total Qts of the driver is a function of all series resistance with the driver. Most software assumes a very small value like 0.10ohms or so. The VS-2.4 had a series inductor for the crossover plus a 1.4ohm resistor. The total DCR of these elements is 2.05ohms. This needs to be scaled to 4.1ohms when modeling one woofer. This is going to raise the Qts of the drivers a lot, which will require a larger box and give a lower f3.
2) Using two woofers in the same cabinet changes the t/s parameters of both drivers. It increases the air load on the drivers which lowers Fs some. This will drop the f3 a little bit compared to your single woofer model.
3) You can't neglect the eq that is built into the crossover's low pass filter. Here is a link to another crossover design from earlier in this thread.
http://members.shaw.ca/rtowsley/xds/crossover_zaph.png
Notice the sloped response from 200Hz to about 2.5kHz? The steepness of this slope affects how much the midrange is attenuated. The more midrange attenuation, the lower the f3 in the bass, to an extent. Note that the steepness of this slope and the amount of series resistance with the woofers from #1 above are interlinked.
4) And then there is the marketing filter
1) The total Qts of the driver is a function of all series resistance with the driver. Most software assumes a very small value like 0.10ohms or so. The VS-2.4 had a series inductor for the crossover plus a 1.4ohm resistor. The total DCR of these elements is 2.05ohms. This needs to be scaled to 4.1ohms when modeling one woofer. This is going to raise the Qts of the drivers a lot, which will require a larger box and give a lower f3.
2) Using two woofers in the same cabinet changes the t/s parameters of both drivers. It increases the air load on the drivers which lowers Fs some. This will drop the f3 a little bit compared to your single woofer model.
3) You can't neglect the eq that is built into the crossover's low pass filter. Here is a link to another crossover design from earlier in this thread.
http://members.shaw.ca/rtowsley/xds/crossover_zaph.png
Notice the sloped response from 200Hz to about 2.5kHz? The steepness of this slope affects how much the midrange is attenuated. The more midrange attenuation, the lower the f3 in the bass, to an extent. Note that the steepness of this slope and the amount of series resistance with the woofers from #1 above are interlinked.
4) And then there is the marketing filter
XdA repair
Jack
Maybe you can help me. I purchased my complete Xd system about the same time NHT pulled the plug on the separates. My system was fine up until a few weeks ago. I had my XdA 'off' for a few days , as I was moving thing around in the room. When I turnd the power switch on , I got a fairly large arch from the back of the XdA. It still played ok , but I was concerned (safety). I decided to open the box just to take a look. I saw on the output board (speaker connection) , that 1 of the ceramic resistors was 'burnt'. There was nothing that looked to be shorted , as the speaker cable is pretty straight forward. I unbolted the board and found 1 resistor with almost severed leads. By chance I had a same resistance ceramic on hand , so I changed it out. Put it all back together and it was fine.
Just today , after a few days of not listening (unit on). , I went to play some music and one channel had only the tweeter playing. I checked all wiring and then noticed the back of the XdA was quite hot. I disconnected everything and opened it up. Now ALL the ceramic resistors are VERY hot (can't touch) , and 1 seems to be 'open'. Everything else inside the XdA looks fine.. I'm curious if you have heard of this problem before. And I'm hoping parts are still available. This has now become a concern , as the XdA does EVERYTHING.
Hope you can guide me
Paul
Jack
Maybe you can help me. I purchased my complete Xd system about the same time NHT pulled the plug on the separates. My system was fine up until a few weeks ago. I had my XdA 'off' for a few days , as I was moving thing around in the room. When I turnd the power switch on , I got a fairly large arch from the back of the XdA. It still played ok , but I was concerned (safety). I decided to open the box just to take a look. I saw on the output board (speaker connection) , that 1 of the ceramic resistors was 'burnt'. There was nothing that looked to be shorted , as the speaker cable is pretty straight forward. I unbolted the board and found 1 resistor with almost severed leads. By chance I had a same resistance ceramic on hand , so I changed it out. Put it all back together and it was fine.
Just today , after a few days of not listening (unit on). , I went to play some music and one channel had only the tweeter playing. I checked all wiring and then noticed the back of the XdA was quite hot. I disconnected everything and opened it up. Now ALL the ceramic resistors are VERY hot (can't touch) , and 1 seems to be 'open'. Everything else inside the XdA looks fine.. I'm curious if you have heard of this problem before. And I'm hoping parts are still available. This has now become a concern , as the XdA does EVERYTHING.
Hope you can guide me
Paul
Paul,
Keep your XdA turned off for now.
Some of the amplifiers in the XdA had a bad batch of output filter capacitors. When these capacitors fail, they can release a lot of smoke as the body of the capacitor melts. The PCB you are talking about at the back of the XdA is a secondary high frequency filter. The fact that the power resistors on it got this hot, means that the primary filters on the power amplifier modules (capacitors) have failed.
The amplifier module with the failed capacitor is now in protection or has blown outputs from the cooked capacitor.
We issued a recall to fix all of the XdAs, but we were somewhat at the mercy of the records that dealers kept and/or whether the end user sent in the registration card.
If you contact NHT, they will take care of this.
Keep your XdA turned off for now.
Some of the amplifiers in the XdA had a bad batch of output filter capacitors. When these capacitors fail, they can release a lot of smoke as the body of the capacitor melts. The PCB you are talking about at the back of the XdA is a secondary high frequency filter. The fact that the power resistors on it got this hot, means that the primary filters on the power amplifier modules (capacitors) have failed.
The amplifier module with the failed capacitor is now in protection or has blown outputs from the cooked capacitor.
We issued a recall to fix all of the XdAs, but we were somewhat at the mercy of the records that dealers kept and/or whether the end user sent in the registration card.
If you contact NHT, they will take care of this.
Jack
Thank you for this information. Very kind of you to pass it my way.
I will contact NHT. I was only concerned by the fact that this unit is all-in-one , and my system might become useless. I did get a nice deal , but it still would have been a big disappointment .
I appreciate your help
Paul
Thank you for this information. Very kind of you to pass it my way.
I will contact NHT. I was only concerned by the fact that this unit is all-in-one , and my system might become useless. I did get a nice deal , but it still would have been a big disappointment .
I appreciate your help
Paul
Jack
Just an update on my XdA issue.
On your advice , I contacted NHT about the problem with my amp/processor. By the end of the day , I received an e-mail from John(owner?). He asked some details , along with serial number and contact info. I described the 'Brown' output caps , one of which seemed to have exploded. His next reply to me was a Return Auth. # with shipping info. He offered assurance that the repairs would be covered under warranty. I packed it up in the original box and sent it via USPS Priority Mail., as I live in NY (NHT is in CA). That was on a Monday. By Thurday I was notified it was in process. On Saturday , John informed me the XdA was ready to ship. I received it on Friday and it looked as though they sent me a new unit; but I thinks the serial # is the same?? Either way , it's back in my system and sounds just fine.
My real reason for writing was to make mention of NHT , and their staff , of very excellent service. It is much appreciated , and will be long remembered.
Paul
Just an update on my XdA issue.
On your advice , I contacted NHT about the problem with my amp/processor. By the end of the day , I received an e-mail from John(owner?). He asked some details , along with serial number and contact info. I described the 'Brown' output caps , one of which seemed to have exploded. His next reply to me was a Return Auth. # with shipping info. He offered assurance that the repairs would be covered under warranty. I packed it up in the original box and sent it via USPS Priority Mail., as I live in NY (NHT is in CA). That was on a Monday. By Thurday I was notified it was in process. On Saturday , John informed me the XdA was ready to ship. I received it on Friday and it looked as though they sent me a new unit; but I thinks the serial # is the same?? Either way , it's back in my system and sounds just fine.
My real reason for writing was to make mention of NHT , and their staff , of very excellent service. It is much appreciated , and will be long remembered.
Paul
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