Nomex 164 -My DIY experience on a 2.5 way

Hi Happy Xmas to all members.
This is my first experience building a 2.5 way based on Nomex 164 designed by Troel using Peerless HDS midwoofer renamed now Tymphany 830875 and ex Peerless HDS tweeter 810921 now remaned Scanspeak D2608 91300.
In the past I have experienced only 3 ways with 10 in woofer. So I will probably have to tune my ears to bass coming from 6.5 driver asnd hope I shall not be disappointed.
 
Just finished painting and am building the xovers from scratch. The most difficult part is winding the inductors. For the measurements I have a LCR module from china, and I shall contercheck its accuracy using LIMP , counterchecked using formula from diyaudio menber Lojzek. Coming soon photos of finished nomex enclosure.
 
Just finished a temporary xover based on the Troels MK1 schematics, but the diy wound inductors surely will be of approximate values as I really doubt the chinese LCR meter module. E.g Testing a known 2.2 mH RAH inductor gives 1.8 mH and a 0.22 inductor gives 0.180 mH as result. All caps used are basic Mundorf MKP audiophiler 3 % value.
The midbass have been broken in for approx 10 hours using 40HZ sine wave, they will have to develop in smoothness further as the compliance is hard when the cone is pressed inside with precaution.
 
Pics

Here is a pic of 2.5 way and tentative xover
 

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Tks zman01. The front panel has been sprayed with automotive grey black aluminium finish, but the sides have only light grey primer on them. I think that I will keep the same tint as finish.
The dimensions are slightly different from Troels recommendations: My enclosure is 220 x 260 x 950 mm instead of 200 X 250 x 950. As the front panel is slightly larger, the xover will probably have to be adjusted. I'll start with the basic xover and do FR/ impedance measurements tomorrow.
 
First measurements of Nomex 164 clone

]Here are a first Frequency response and impedance sweep after approx 10 hrs break-in. I shall not give my impressions on the sound as I feel that the mid bass cones are still stiff and need some more time to loosen. The impedance is almost similar to Troels.
Frequency response my nomex .jpg

Impedance sweep 45 Hz.jpg
 
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Change in the right impedance measurement

Hi to all, after some time I come back to my finished project and just to keep the hand regarding measurements, I took some impedance measurements. To my astonishment I notice that the right impedance has changed and does not look ok, while the left one is still intact as per Troels project. Can anyone explain the cause of this change from the pics?
 

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Last edited:

URI55

Member
2019-09-28 1:42 pm
Hi to all, after some time I come back to my finished project and just to keep the hand regarding measurements, I took some impedance measurements. To my astonishment I notice that the right impedance has changed and does not look ok, while the left one is still intact as per Troels project. Can anyone explain the cause of this change from the pics?


Check if both woofers are connected/working by measuring DC resistance of the box.