Peerless NOMEX 164
            Copyright 2010 Troels Gravesen

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Peerless HDS164 Nomex 830875 + ScanSpeak Discovery tweeter D2608/9130
Click links to download driver specs.

I've had these drivers on the shelf for more than two years and since the Peerless 850438 drivers were discontinued, I've had regular requests on a new 2-way from Peerless drivers, thus this "NOMEX 164" with the Peerless drivers shown below. The main reason for my evasiveness was a feeling of what these drivers could offer I hadn't heard many times before, but as a hifi dealer advertises: Don't be afraid to be surprised!

I think these drivers deliver an excellent cost performance ratio and I was really surprised when I made the final set-up in our living room driven by my JungSon class A amp. I usually make my test crossovers from Superior Z-caps, good baked coils and 10 watt MOX resistors and all in all these drivers makes me wonder why I ever spend money on "high-end" drivers. These NOMEX drivers have an excellent midrange presentation and if you're seeking a driver that will handle vocals and piano notes with grace, try out these drivers. I was pleasantly surprised.
The 830875 is a bit peaky in the 4-6 kHz range, but nothing that can't be fixed in the crossover, and nothing that seems to distress the ear. The Peerless HDS 810921 (now ScanSpeak D2608/9130) tweeter is a very well engineered unit, impeccable finish and assembly - all reflected in price, which is not down to XT25 level, but worth every penny. I won't make an XT version as this D2608/9130 does so well, so please do not ask.

I've picked some really good coils for the crossover and added Superior Z-caps because these drivers deserve it. Should you want to save approx. 60 EUR, use standard polyprops. The drivers alone will be some 300 EUR from the cheapest supplier I can find (Dutch supplier). I won't recommend this supplier as they don't respond to emails and generally pack poorly, so don't ask who it is.

QUESTIONS having the answer NO:
Can I use another tweeter? Can I change the front panel layout and driver placement? Do you have more detailed drawings? This should eliminate the bulk of mails.
Can I use it up-right? Depends. I tried everything from up-right to a 5 deg tilt and ended up with some 3-4 deg tilt allowing listening at tweeter level. This made the best vocal performance to me. I suggest a tilted base plate as shown with adjustable rear feet/spikes.

I assume these HDS drivers on the German market are: Peerless HDS N-6-33/08 (midbass) and Peerless HDS DT 26/08 (tweeter). I can't figure out why the German market always re-label standard drivers. This kind of market protection is long gone with current internet sales. At Strassacker you can find both drivers holding exactly the same data.

 


The Crossover
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R1061 is optional. Leave it out and you get plus ~1-1.5 dB treble level. See graphs below.

Crossover Kit
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Complete crossover kit excl. drivers is available from Jantzen Audio:
contact@jantzen-audio.com


Crossover kit incl. ports, terminals, solder tag strips, wire, caps and coils.
Cut ports to 80 mm length for Fb = 45 Hz and 34 liter cab volume.

Crossover Layout


Final crossover. A little different from the drawing.
You need to add two wires on the board. One from + IN to R1011/L1011 (white) and one from L1041 to ground (black/white).

The board shown here is 140 x 270 mm, 12 mm baltic birch.


Click image to vie large.


The Cabinet
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Click image to view large.

Check this file for cabinet damping suggestions.

Port tuning


Box simulation for two drivers. I suggest port tuning of 45 Hz providing F3 = 45 Hz.
Ports for Fb = 45 Hz:
60 mm diameter: 55 mm length.
65 mm diameter: 68 mm length.
68 mm diameter: 80 mm length (Jantzen port)
70 mm diameter: 82 mm length.

You may increase cabinet size to 40 liters without problem and get another 3.5 Hz bottom end extension.
Maintain port tuning Fb = 45 Hz and cut 68 mm (D) port to 60 mm length.
Increase cabinet depth and maintain height and width.

The 830875 drivers have a fairly high Fs and take some heavy beating to break in. And don't be afraid to do so, the 33 mm voice coil takes a lot of heat and my JungSon drove the speakers to 95 dB @ 2 meter without noticeable distortion. Well done! They deliver a punchy bass that even can be felt. Do not expect anything in the 20-40 Hz range. If you look for earthquake experiences, add a decent 10-12" sub. I actually think these speakers are excellent for this application and you may try adding a small amount of foam to the vent to make an aperiodic tuning to fine-tune sub-sat integration.


These test cabs has seen a lot of drivers. Last time the CNO25 and I could modify the CNO25 front panels to accommodate the Peerless drivers.
I really hate truncated drivers as they make routing very critical.
I would make the front panel from a 165 mm center panel (minimum diameter of Nomex driver) and add fillets to make 200 mm total width.
In fact, you really don't have to flush-mount the Nomex drivers, if you can live with this. The tweeter must be flush-mounted as seen above.


Measurements
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Left: Driver response from shown cabinet driven without crossover. The midbass a little peaky at 4-6 kHz but generally a smooth roll-off profile.
Right: SPL/2.8V @ 1 meter for the two speakers. Quite a matched pair! Overall system sensitivity = 90-91 dB.


Left: SPL from various tweeter attenuation. Blue with R1051 in place. Red = R1061 left out. Take your pick!
Right: Final system impedance. Minimum = 3.5 ohms at 200-300 Hz.


Left: SPL from drivers driven from crossover. Yellow = lower bass unit.
Right: Blue = SPL from inverted tweeter polarity. Point of crossover ~3300 Hz.


Left: CSD/20 dB scaling. Right: CSD/40 dB scaling.


Nomex 164 builders

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