www.audioexcite.com

(Click on picture to zoom)

This short blog post describes the difference between the discontinued SB Acoustics SB17NRXC35-4 loudspeaker driver and its replacement SB17NRX2C35-4. In the two pictures above you can see the old NRX driver to left and the new NRX2 driver to the right. The only visible difference is that the new NRX2 driver has a larger dust cap and the label on the backside of the magnet is different.

The questions are — Do they measure the same and is the new NRX2 driver a drop-in replacement for the old NRX driver? I will try to answer this by providing some measurements and a simple cross-over simulation below.

T/S Parameters:

(Click on picture to zoom)

Left: SB17NRXC35-4 T/S parameters measured using “added” mass method in horizontal position.

Right: SB17NRX2C35-4 T/S parameters measured using “added” mass method in horizontal position.

According to the official specification sheets, the old NRX diver should have about 2dB higher sensitivity, but in real life they have just about the same sensitivity as the new NRX2 drivers.

Impedance:

(click on picture to zoom)

Left: Free-air impedance. NRX vs. NRX2.
Right: Close-up of free-air impedance. NRX vs. NRX2.

The impedance plot is similar between the two versions, but there are some variation between 08-2kHz and for the NRX2 version the impedance plot shows a small wrinkle around 6.1 kHz, where the cone break-up is.

Frequency measurement conditions:

The mid-woofer is measured mounted on a baffle in an 17.6 liter closed enclosure with the following conditions:

Baffle size (WxH): 20×40cm. No baffle edge round-over.
Driver position: Mounted on center-line with driver unit center 17cm from the bottom of the baffle.
Mic position: 1m distance, on mid-woofer-axis.
Smoothing: No smoothing applied. Measurement valid down to 275Hz.

(click on picture to zoom)

Left: Frequency response on-axis. NRX vs. NRX2.
Right: Frequency response 15deg off-axis. NRX vs. NRX2.

The new NRX2 version has a smoother frequency response between 0.8-4kHz, but on the other hand more pronounced break-up modes between 4-8kHz compared to the old NRX version.

Distortion:

Measurement setup:

• Mid-woofer near-field measurement at 18cm
• Frequency Range Mid-woofer: 200-10000Hz
• Baffle size WxH: 20×40cm

The distortion measurement shown is done in near-field and the amplifier output level was adjusted so that the fundamental is 95dB at 1m. This setting simulates a high listening level.

(click on picture to zoom)

Left: = SB17NRXC35-4 — 95dB @ 1m

Right: = SB17NRX2C35-4 — 95dB @ 1m

Both the new NRX2 and the old NRX are low distorting loudspeaker drivers, but there are some differences due to different cone edge resonances and cone break-up modes.

Cross-over simulation:

(click on picture to zoom)

The cross-over simulation shows a simple electrical third-order cross-over with an acoustical fourth-order Linkwitz-Riley cross-over topology. As can be seen by the frequency plot the NRX2 has a smoother response, but the cone break-up modes are less suppressed compared to the old NRX version using the same cross-over.

Conclusion:

The two NRX versions are similar in many aspects, but are they interchangeable of each other in the same cross-over design?

Maybe, but some fine tuning might be necessary depending on the cross-over design. Also, another factor to consider is that if combining the two NRX versions with the same tweeter, the drivers relative acosutical off-set is about 3-4mm larger using the new NRX2 driver compared to the old NRX driver.

For further measurement details of the two NRX versions, see: SBAcoustics SB17NRXC35-4 and SBAcoustics SB17NRX2C35-4.

On the test bench we have the SB17NRX2C35-4 6″ mid-woofer from SBAcoustics.

Note! This driver replaces the discontinued SBAcoustics SB17NRXC35-4 loudspeaker driver.

For further details see: SBAcoustics SB17NRX2C35-4

On the test bench we have the SB17NRXC35-4 6″ mid-woofer from SBAcoustics.

Note! This driver has been discontinued, but can be found second hand and is still available at some shops!

For further details see: SBAcoustics SB17NRXC35-4

On the test bench we have the Satori MW16P-8 6.5″ mid-woofer from SBAcoustics. This is a very nice performing mid-woofer

For further details see: SBAcoustics Satori MW16P-8

Hi everyone,

From now on when I publish loudspeaker driver measurements, I will present it slightly different than before!

First of all I will visually present the frequency measurements and impedance differently. In the past I’ve used screen shots from the Holm Impulse and DATSv2 software, but in the future I will use LspCAD 6 Pro to visually present the frequency graphs. In that way I can e.g. show all measurements between 0 and 60 degrees in one graph. Below is an example how it will look like.

(click on picture to zoom)

Secondly I will present and measure the Thiele Small measurements slightly different for all mid-woofers and woofers. All drivers will be burnt in for 3 hours at their resonance frequency and slightly below the x-max excursion limit of the driver. After the driver has cooled off, it’s measured in two ways.

First the driver will be measured using the “added” mass method in a horizontal position. Secondly the driver is measured using the “known” mass method in a vertical position. In this case the “known” mass is the Manufacturer’s specified Mms of the driver unit.

The driver units are always measured in pairs or more and the individual driver samples measurements will be presented as well as the average of the two drivers.

Regards

/Göran

The Hulgich Audio, Holton Precision Audio and the AudioExcite Loudspeaker Design Team:

Hi everyone!

I’m sorry for that I haven’t had time to update the website for the last six months, but you can read about the reason for it below. There has been a lot of work designing two new Highend loudspeakers for Hulgich Audio.

The 12th-14th of October I attended the Melbourne International Hifi Show in Australia together with Hulgich Audio and Holton Precision Audio.

We had a great success showcasing two new Hulgich Audio models, the Duke and Nina loudspeakers.

The Duke is a brand new loudspeaker and after a long and hard work and with only one week marginal, we finished it just in time before the Show. The Duke wasn’t the only new product at the Show, the Nina was also for the first time demoed to a broader public.

Both models were received well and got very good reviews.

We were awarded together with Holton Precision Audio the  “Best Sound (Australia) – Highly Commended” award!

I want to thank and congratulate Nicolas Hulgich and Anthony Holton for an exemplary well done work with the Hifi show and for the great time I had with them and the rest of the Hulgich Audio and Holton Precision Audio team in Australia.

I also want to thank all the Hifi Show attendees and other exhibitors for their very friendly reception.

Read more about Hulgich Audio loudspeakers and the  International Hifi Show here:

Melbourne International Hifi Show 2018 Report
Hulgich Audio News
Hulgich Audio Reviews
Hulgich Audio Awards

/Göran
AudioExcite Loudspeaker Design

Hi,

I’ve added the distortion measurements for the Revelation Two – M4 WG speaker.

It has excellent distortion performance!

For details see: Revelation Two – M4 WG

Hi everyone,

It has been a while since I on this website released a new loudspeaker design , but at last here it is despite being a year late than planned.

The Revelation Two – M4 WG is a medium sized stand-mount loudspeaker using prefabricated enclosures from Dayton Audio or even better for those who enjoy wood working, custom built enclosures can be built as long as the loudspeaker driver layout is kept according to the design drawings.

This is a fun loudspeaker that sounds a lot larger than it is.

For details see: Revelation Two – M4 WG

Happy DIY,

/Göran

Hi everyone,

Here are some pictures and comments from the HighEnd Hifi show I visited 17-18th of February 2018 here in Stockholm, Sweden.

Stockholm High End 2018