• The Vendor's Bazaar forum is for commercial offers and transactions. Only unmoderated members can post here.

    diyAudio provides this forum for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members. Use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

For Sale: NHT Loudspeaker drivers and amps-Discussion Thread

Jump to Latest
#241
They're currently not being used in any kind of DIY fashion, but they are sweet indeed. 😀

M60_sitting_area.jpg



They're very impressive, Jack. Thanks.

Keith
 
#246
homemade said:


Maybe you can give us some info on the c/o too
Click to expand...

Oh, I'm a total cheater on that one- I'm using an XdA to drive them. I already had it as part of an Xd package. Changing the XdA to an M60-specific filter involved only a couple mouse clicks.

My extra XdS's will probably be the ones to receive passive crossovers down the line. So goes the plan, anyway.

Keith
 
#247
HornsKeith said:


Oh, I'm a total cheater on that one- I'm using an XdA to drive them. I already had it as part of an Xd package. Changing the XdA to an M60-specific filter involved only a couple mouse clicks.

My extra XdS's will probably be the ones to receive passive crossovers down the line. So goes the plan, anyway.

Keith
Click to expand...


Lucky you🙂

Just wondering which speaker (M60 or XdS) you would consider a lower distortion system when used with the subwoofer(+120hz).

I really like the looks of the M60 , but I'm concerned about using it with the passive crossover . That woofer has a much lower break-up mode than the XdS. M60 must be killer with the XdA
 
#248
homemade said:
I really like the looks of the M60 , but I'm concerned about using it with the passive crossover . That woofer has a much lower break-up mode than the XdS. M60 must be killer with the XdA
Click to expand...
I haven't looked at this speaker much, but from the looks of it, the crossover schematic included in the measurement package at Jack's site includes a notch filter for the cone breakup.
 
#249
DcibeL said:

I haven't looked at this speaker much, but from the looks of it, the crossover schematic included in the measurement package at Jack's site includes a notch filter for the cone breakup.
Click to expand...


Yes , I did notice that the passive c/o has a notch included. It's just that I think this is a modeled filter. My limited passive c/o history has shown me that driver variation alters the needed real world components. That narrow 10db+ driver peak is just 1 octave above the c/o point. I really don't have the expertise(or wish ) for redesigning . For me, the XdS just appears more forgiving.
And yes , I guess I'm just looking a gift horse in the mouth😉
 
#250
Jack Hidley said:
I haven't sold a single Jensen 15" woofer yet. I honestly can't believe it.

The drivers are fairly old, but in perfect shape. They were made by Foster about 10 years ago. By this time, pretty much all companies in Taiwan were using foam that has antifungal agents in it and was much more UV and ozone resistant.

I can take my finger and smash it into the surrounds on these woofers no problem. The foam rebounds perfectly afterwards.
Click to expand...

It's not the drivers age, but I'd love to see a response curve. You mention 2 or 3 way pro type system. Would these work crossed at 1200? How is the breakup and would I need a notch?
 
#251
It may be a modelled crossover, but it's modelled using Jack's measured response of the driver, in the speaker cabinet itself. How much more accurate do you want?

These are Seas Excel drivers, the build quality is sufficient that the resonant peak will remain the same from driver to driver.

As for comparing the XdS versus the M60, The M60 has a larger cabinet, and a larger woofer, so it'll be better if you want to use the speakers without a subwoofer. With a subwoofer, The M60 could be crossed over lower, at 80Hz. The Xds should be crossed over at 100-125Hz. Other than that, it's just about looks. 😉
 
#252
" It may be a modelled crossover, but it's modelled using Jack's measured response of the driver, in the speaker cabinet itself. How much more accurate do you want?"



Certainly a good point.

In the crossover provided , the notch filter states 'total resistance of resistor and inductor is 1.35 ohms'
The resistor is shown as 1.39 ohms. Is this a typo?
 
#253
I haven't had the time to optimize an X2 to EQ the XdW yet. I did get a chance to measure an XdW using the X1 crossover. The measurement is attached. The response on the low end is very good. I'm pretty sure the response on the high end can be improved. The Q of the resulting LP filter is fairly low.

Both the M-60 and XdS data packages have THD+N measurements for the drivers in them. Pleeeeassssse look at all of the measurements in the data packages. It is their for your benefit, so you don't have to ask questions and then wait for the answer.

I've measured hundreds of Excel drivers. The cone is machined, so the resonant peak does not vary.

The data packages also contain the actual frequency response of the speakers with the crossover in the schematic actually, physically attached to the speaker driven by a real amplifier, sending real electrons to the speaker🙂

The 1.35ohm versus 1.39ohm is a typo. I have no idea which is "correct". The response difference at the resonant peak is probably on the order of 0.08dB.

I don't have a response curve for the Jensen 15" woofer. I don't have any baffles to put it in either, so it won't be easy to measure. It was used in a speaker with a 6.5" midrange just above it. My guess is the crossover was somewhere between 350Hz and 800Hz.
 
#254
Jack,

A few questions/comments:

1) I cracked open the Foster amp and was able to see VR603 that you spoke of in an earlier post. A complete schematic would be preferable, but without that your measurements have been extremely helpful (thanks). Any chance a schematic could be posted that has these changes/additions to the amp?

2) Did you adjust the other VR that was on the power amp board?

3) I am curious about the power handling capabilities of the AR 12" and the NPT-080-11-1. I don't think this is a critical parameter; my main purpose would be to help ensure that I do not exceed Xmax by choosing the HPF section (for the AR 12") and the crossover freq (for the Peerless) such that they do not exceed their Xmax.

I'm using 50W for the 5.25" Peerless and 100W for the AR 12", both guesses.


Barry
 
#255
Barry,

The WF-100 is a generic plate amp platform that Foster customizes for lots of customers. Unfortunately, I don't have a schematic for this particular version of the amplifier. The amplifiers are about 10-12 years old and no one at Foster is going to want to try to work backwards to dig up a schematic for this particular model.

This is a general warning to anyone who has this idea: DO NOT attempt to try to get a schematic from Foster for the amplifier. Foster manufacturers products for other brands. They do not have the time/manpower to provide customer service to the DIY market.

I'm not sure what VR604 does. My first two guesses would be a bias adjust or a DC voltage trim.

If you use a 30Hz HP filter on the AR 12" you should be fine. Anything higher than 100Hz HP filter on the Peerless should make it indestructible.
 
#259
Thanks Jack!

Jack

I finally took the time to open all my boxes (XdS, X-2, M-60, stands, etc.) to check the contents. The XdW sub is scheduled for delivery today.

After a visual inspection, I can confirm that they all got here without any external damage. :up:
I must say I was not feeling that good when opening two of the stand boxes that had big gashes (courtesy of UPS). Whatever punctured one of them was not small - it made through the bottom part of the stand box and through the inner box containing the base. It missed the base by less than 1/4-inch. :bigeyes:

The boxes look even nicer than the pictures and I cannot wait to have them fitted with adequate crossovers.
I would buy a XdA in a heartbeat if they become available. In the meantime I will play with active and passive crossovers - that will keep me busy for a while. :hphones:

Thanks Jack for making this purchase possible - currently I would not be able to afford these nice toys if I had to pay the regular street price. :cloud9:
 
#260
Jack Hidley said:
Ok, mystery solved, in a good way. This version of the amplifier has a feature that I wasn't aware of. Foster included a spectral tilt control, but they put it in the power amp section.

There is a variable shelving circuit on the power amp PCB. This is a shelf circuit where the slope is adjustable, sort of. In reality, the corner frequency of the shelf is being moved up and down as the adjustment is made. This moves the the transition area of the shelf into different places in the passband. See the first attachment. This is an unmodified amplifier with VR603 turned full CCW, centered and full CW. As shipped the adjustment is near centered I believe.

At full CCW, the slope is about 1.2dB/octave. Very low. At anything beyond centered, the slope is about 6dB/octave. Note that as the pot is turned CW, the gain of the amp drops a lot because you are sliding the corner frequency of the shelving circuit down lower.

If you want to completely disable this circuit, put a 10k resistor across R662 on the power amplifier PCB. The best place to do this is on the solder side of the PCB. Then you get the response curves shown in the next attachment.

For most applications, I think people can just turn it full CCW and forget about it. If you have a low Q alignment, you can use it to tilt the low end up.

The 3rd order high pass filter is still independently adjustable.

I'll try to update the notes on the website tonight regarding this.
Click to expand...


I just purchased 2 of these plate amps for use on my open baffle bass section. I have to believe that this spectral tilt feature will really work well here. The HP filter looks to be useful also. Changing it to 12db looks easy , even for me.

Still can't decide which speaker to buy(XdS or M-60). Thinking about getting the XdS and installing the drivers on my OB ; kind of like a Jamo 909 clone. I have 2 15" per baffle already mounted. Too bad I bought those drivers before I found this thread(yes , I realise this thread is quite old). 4 of those 15" Jensons might be very good.
 
You must log in or register to reply here.
Top Bottom