Fountek NeoCD3.5H



NeoCD3.5H_1The Fountek NeoCD3.5H is a horn-loaded true ribbon tweeter that uses a reinforced sandwiched-aluminum ribbon diaphragm together with a strong neodymium magnet.

It has wide horizontal off-axis dispersion, an extended frequency response and for a medium sized ribbon good vertical off-axis dispersion as well.

Key features:

  • Horn-loaded, true ribbon design
  • 9mmX60mm ribbon element
  • Reinforced sandwich diaphragm
  • Strong Neodymium magnet
  • Build-in impedance convertor
  • 95.5 dB sensitivity combined with an extended frequency response up to 30kHz
  • Extremely fast transient response with wide horizontal dispersion


Fountek Spec sheet: NeoCD3.5H

T/S Parameters:


NeoCD3.5H_T-S parameters

This is the NeoCD3.5H parameters published by the Manufacturer.



NeoCD3.5H_Imp 1L vs 2R WT2

(click on picture to zoom)

Sample 1 = Green
Sample 2 = Blue

Almost identical impedance curves with only a small difference in the nominal impedance between the two ribbon tweeter samples.



Frequency measurement conditions:

The tweeter is measured mounted on a baffle with the following conditions:

Baffle size (WxH): 24×35cm with 18mm round-over.
Driver position: No flush-mount, mounted on center-line with driver unit center 8cm from the top of the baffle.
Mic position: 1m distance, on tweeter-axis.
Smoothing: 1/24 octave smoothing applied.
Protection: A 47uF protection cap is used.

NeoCD3.5H_Freq 1L vs 2R 0degNeoCD3.5H_Freq 1L vs 2R 15deg

(click on picture to zoom)

Left: Frequency response on-axis (Blue=sample1, Red=sample2).
Right: Frequency response 15deg off-axis (Blue=sample1, Red=sample2).

They have essentially identical frequency responses. From 15kHz up to 20 kHz we have a rising frequency response on-axis, but as we go off-axis it smoothes out.

Even though the ribbon tweeter isn’t flush-mounted in this measurement, the frequency response is flat without any large dips or peaks and it doesn’t seem like flush-mounting is necessary. This makes the enclosure building an easier task.

NeoCD3.5H_Freq 0-15-22deg

0deg = Blue
15deg = Red
22.5deg = Green

NeoCD3.5H_Freq 30-45-60deg

30deg = Blue
45deg = Red
60deg = Green

The NeoCD3.5H ribbon tweeter has a very extended and wide off-axis frequency response.



Measurement setup:

  • Tweeter near-field measurement at 10cm
  • Frequency Range Tweeter: 1000-10000Hz
  • Baffle size WxH: 24×35cm

The distortion measurements are done in near-field and the amplifier output level was adjusted for each driver so that the fundamental is 90dB and 95dB at 1m. This setting simulates  medium-high and high listening levels.

NeoCD3.5H-1L -- 10cm 90dbNeoCD3.5H-2R -- 10cm 90db

(click on picture to zoom)

90dB @ 1m
Left = Sample 1
Right = Sample 2

NeoCD3.5H-1L -- 10cm 95dbNeoCD3.5H-2R -- 10cm 95db

(click on picture to zoom)

95dB @ 1m
Left = Sample 1
Right = Sample 2

We can see that tweeter sample 1 has a higher distortion profile at higher frequencies than the sample 2, but with only two driver samples to test, we cannot tell if this is an overall driver consistency issue or not.

Compared to a 1” dome tweeter, this small ribbon tweeter has an overall higher distortion profile, but with a proper cross-over design the distortion can be handled and shouldn’t be an issue.

The NeoCD3.5H ribbon tweeter should preferably be crossed-over at 4kHz or higher, but a 3-3.5kHz cross-over point can work if steep filters are used e.g. a fourth-order (acoustical), third-order (electrical).