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For Sale: NHT Loudspeaker drivers and amps-Discussion Thread

amp question

how does the Foster WF-100K subwoofer plate amplifier offered here compare to what PE has for sale. ? i know the cost is cheaper but what of quality as i have no experience at all with these.

lots of comments about humming from the Dayton plate amps in the reviews.
 
I'm pretty interested in the XdS speakers too...

but it looks like the cost of parts for the crossovers and enclosures
will be more than what they're asking for the speakers and stands!

Sad to see NHT take a break, i've always lusted for the 3.3s : )
 
Hey Jack. Any more info about the XDW drivers? I'd like to purchase a pair of the XDS sats and 4 of the woofers used in the XDW. My plan is two of the 10 inch woofers in powered bass bins under each XDS crossed at 150hz or maybe higher which brings up my next question. How's the distortion on the XDWs in the 150-200hz range? I'm also torn between an all passive system vs a behringer DCX2496 and 4 channels of amplification and two plate amps( i already have). I have 4 11-075s already and i'm also wondering if there's a substantial improvement potential by using the XDW woofers instead? My first guess tells me the 11-075s won't do so well over 100hz.
 
moe29 said:
I'm pretty interested in the XdS speakers too...

but it looks like the cost of parts for the crossovers and enclosures
will be more than what they're asking for the speakers and stands!
Click to expand...
You've lost me. The XdS Speakers come with the XdS enclosures for $100ea, plus $40ea for stands. Crossover parts will be about $30 per speaker. Heck of a deal!
 
i guess i was just looking at some expensive inductors.

i was also figuring that the crossover would have to be constructed
in it's own enclosure - do you think you could mount it inside the speaker?

You're right - it's a great deal if the crossovers are that cheap!
 
I was planning to mount crossover inside the enclosure. I believe it's very possible, however I don't have any XdS speakers in my hands yet...A week or so and they should be.

The most expensive part in the crossover will be the large inductor for the woofer. If you spend more than $20 on this part you are wasting your money. 😉 Sledghammer steel laminate from Madisound is something like USD$13, 16AWG air core from Solen (Canada) is about the same.
 
The XdS with a 24dB/octave active crossover will work well. There are two places to implement the BSC. One is between the amplifier and the woofer. The other is between your crossover unit and amplifier. The second one is going to be a lot cheaper to do, not result in any iductor distortion and give you more power available to drive the woofer.

This can be done with two resistors and a capacitor. You need to know the output impedance of your crossover and the input impedance of your power amp. I don;t have time to draw the circuit and explain the math. Maybe someone else can.

Here is a page that explains how to do it actively:

http://www.t-linespeakers.org/tech/bafflestep/bstepcompo.html

I've attached a THD measurement of the XdW at 1M. The SPL is about 95dB in this sweep from 70-100Hz. There is a LP filter in the amp around 200Hz causing some rolloff. The actual XdW woofer is flatter than what is shown. The woofer can be used quite high in frequency from a THD standpoint. It has very low inductance.

There are some mechanical considerations with the driver though. I'm not going to go into those yet. I'll do that on the sale site when I get to it. I don't have an eta yet.

The 075s aren't great from a distortion standpoint anywhere much less above 100Hz, from an inductance standpoint. The XdW woofer will sound much better.

Do it all active.

You might be able to fit the crossover inside an XdS, but it will be very hard to stop inductor crosstalk and keep the inductors away from the woofer motor. There is a shelf brace just above the woofer. Just use masonite, zip ties and hot melt. Screw the mess to the back of the speaker. No one looks there🙂
 

Attachments

Nearfield swept sine measurement at the same drive level as the measurements above. Note: The multiple steps in the response curve are an artifact of the low signal to reflection ratio in this measurement from the woofer on the opposite side of the cabinet. These steps can be ignored.
 

Attachments

I'm curious to know how well the DCX2496 would do as a substitute for the XdA processor. Maybe Jack could comment. I have a DEQ2496 I 'd like to try for EQ in digital domain. My concern for the DCX is the required 6 gang volume control ,but that's another story. These together might be a cheap alternative for the missing XdA ; amps not included
 
The DEQX processor in the XdA and the DCX2496 work quite a bit differently.

The DCX allows you to have standard HP and LP filter types for crossover functions which have the normal associated phase shifts and problems. The DCX also uses IIR filters for all of the parametric EQ which are not linear phase. With the DCX, you adjust your crossover filters, manually adjust the very small number of parametric EQ points available to get flat driver response, then play with the delays between channels to get the drivers in phase at the crossover frequencies. The end result is a system that still has fairly flat response, ok power response, and has the same nonlinear phase response that most speakers have with moderate overall group delay (1-4msec).

The XdA allows you to use standard HP and LP filter types or very high slope linear phase FIR filters for the crossover functions. You take impulse response measurements of the drivers in the system. The DEQX software takes these impulse responses, takes your selected crossover frequencies, slopes, etc and calculates the required impulse response correction filters for each driver to make the entire system have perfectly flat frequency response and phase response, but with more group delay (5-15msec). The total amount of allowable latency (group delay) is an adjustable parameter during the filter creation. The higher this value, the lower in frequency the resulting system will be linear phase. This is just the laws of physics at work here. Once the filter set is finished, you can add a number of parametric IIR filters to tweak the tonality of the speaker however you want.

This is a very short overview of the comparison between the two. Virtually all of the commercially available DSP boxes for speaker processing use the operational paradigm that the DCX uses, because it is much easier to write the software for (which is already supplied by the DSP vendor) and it is the paradigm that most people are used to, since it is really a glorified analog EQ/crossover that just happens to be digital.
 
10" driver

Jack, I am looking for 3 - 4 ohm 10" drivers. You mentioned, several posts earlier in this thread that you had some. Were you referring to the XDW drivers? If not what are they? I am looking to cover the 50 to 150hz range. Thanks.
 
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