Arc Audio “Black 1.0” 29mm Dome Tweeter

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The Arc Audio Black Series is a series of speaker drivers made by a well-known Denmark OEM. Arc has put their tweaks on some of this company’s products and released their own line of drivers geared toward the car audio community, known as the Black Series. From this series is a set of tweeters called the 1.0.

You can find more information from Arc’s product information page here.

The Black 1.0 Tweeter caught my eye for a couple reasons. It has:

  • Removable flange
  • Small mounting depth
  • Nice aesthetics

The flange itself is a twist-lock attachment which makes it easy to remove. Also included are mounting cups (not pictured).

All in all, physically, I really like these tweeters.

I quickly took down some dimensions found below. Please see manufacturer specs linked above for more information.

  • OD – 64.5mm (with flange)
  • OD – 48.2mm (without flange)
  • Mounting Diameter – 44.6 (taking in to account the leads)
  • Mounting Depth – 26.5mm (with mounting cup)
  • Mounting Depth – 20.0mm (without mounting cup)

Thiele-Small and Impedance Data

Electrical Parameters
Re 3.47 Ohm electrical voice coil resistance at DC
Le 0.014 mH frequency independent part of voice coil inductance
L2 0.014 mH para-inductance of voice coil
R2 0.58 Ohm electrical resistance due to eddy current losses
Cmes 116 µF electrical capacitance representing moving mass
Lces 0.22 mH electrical inductance representing driver compliance
Res 2.91 Ohm resistance due to mechanical losses
fs 1005.4 Hz driver resonance frequency
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f ct 1003.5 Hz driver resonance frequency in enclosure
Mechanical Parameters
(using test encl.)
Mms 0.117 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 0.094 g mechanical mass of voice coil and diaphragm without air load
Rms 0.345 kg/s mechanical resistance of total-driver losses
Cms 0.215 mm/N mechanical compliance of driver suspension
Kms 4.65 N/mm mechanical stiffness of driver suspension
Bl 1.002 N/A force factor (Bl product)
Loss factors
Qtp 1.164 total Q-factor considering all losses
Qms 2.135 mechanical Q-factor of driver in free air considering Rms only
Qes 2.551 electrical Q-factor of driver in free air considering Re only
Qts 1.162 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.0164 l equivalent air volume of suspension
n0 0.63 % reference efficiency (2 pi-radiation using Re)
Lm 90.19 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 90.8 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
rmse Z 2.18 % root-mean-square fitting error of driver impedance Z(f)
Series resistor 0 Ohm resistance of series resistor
Vbox 0.296 l volume of enclosure
Sd 7.35 cm² diaphragm area

A fairly nice resonant frequency (Fs) of about 1khz. The delta from the nominal impedance of 3.60ohm at 3.0khz to 20khz is only 0.80ohm (approximately). Le is low at 1.4mH.

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Frequency Response and Harmonic Distortion at 2.83v/1m

The nominal measured SPL at 2.83v/1m is about 83.382, averaged from 1khz to 10khz. This is about 1dB down from the Scan D3004/602000 I tested recently.

Like some other tweeters, there is a dip in response from 1.5khz to 5khz made more apparent by the boosted response in the top end. I assume this is to help off-axis performance which it does well at 30 degrees. However, at 60 degrees there’s a more distinct rolloff. While the response at this angle is only down 5dB from the 30 Degrees measurement at 10khz, you can see the difference is more apparent at this angle compared to the on-axis measurement than the difference between on-axis and 30 degrees off axis.

To achieve a more real-to-the-source response, the top end should be more flat and not curved. But, there seems to be a strong trend in many tweeters I’ve seen lately (and tested tweeters) that have this same profile of an increased top end. I’m not sure if this is tied to trying to achieve an off-axis response that still has more off-axis content to it or not. For car audio use when off-axis mounting is typically used, this is likely the case.

Response smoothness is pretty good. There’s a peak in response at 15.6khz which shows up in all axes which means it is likely a cone breakup issue. But, at nearly 16khz I can’t say it’s something I would really fret.

You can see non-linear performance is dominated by 2nd order distortion near Fs. This dips below 1% (relative to the mean fundamental) at ~1.6khz. In my opinion, a non-issue at this volume level.

Let’s ramp up the voltage input to see what happens at higher volume…

Harmonic Distortion at 5.5v in the Nearfield

Note: This measurement was taken at 4.75″, equating roughly to 96dB at 1 meter.

Since this is a tweeter, I zoomed in on the HD response to focus on the area above 700hz (notably, response above 1khz).

My personal THD ‘caution zone’ is 3%. 1% is detectable by some depending on the listener and source material along with other factors. I feel 3% is a good all around number so I’ll evaluate based on that.

The areas where you cross the 3% threshold are:

  • Below 1.6khz
  • 2.3khz to 2.9khz (up to 4% THD)
  • 8.8khz for a small instance (up to 4% THD)

These crossing points are comprised of 2nd order distortion almost exclusively.

Third order distortion is kept below 1% above 2khz.

Based on this data, you can likely cross these tweeters down to about 2.5khz without significant distortion. This would attenuate the 4% THD in the 2.5khz area. Power levels will need to be considered and you may find you’ll need to go higher in crossover. Overall, however, I don’t see anything that is a red flag for typical 1″ dome tweeter crossover points and these will probably do well to mate with just about any standard mid/woofer in the 5 inch to 7 inch range. However, the points passband between 5khz to 7khz do make me curious as to what the audible effect may be. As usual, let your ears be a guide.

Since HD testing is only one small aspect of non-linear distortion testing, let’s look at some more data.

Intermodulated Distortion (Voice Sweep at 5.5v)

This measurement was done in the nearfield as well. The bass tone was fixed at ~100hz (0.1*Fs) and the “voice” tones were swept from 800hz to 10khz.

As seen with the HD testing above, the contributing factor to non-linear distortion with this driver is 2nd order distortion. Without measuring with the LSI, I can’t say for sure what this is caused by but my guess is there is assymetry in the suspension, causing the rise in 2nd distortion at Fs, which tapers off below Fs. This decline would give the appearance of higher distortion at frequencies near Fs. In this case, if the driver’s Fs were shifted to be a bit below, you could likely get away with an even lower crossover point. However, I don’t see this as a staunch hindrance simply because most don’t want or need a standard sized tweeter to cross below 2.5khz. This driver does a good job overall of mitigating the 2nd order distortion at Fs; keeping it to below 6%.

Like with the HD plots above, you can see issues at 2.4khz and 8.9khz in the IMD measurements.

This essentially tells you how much power you can expect to lose due to compression from the initial voltage measurement to the last. At 4khz the initial 1v measurement has a measurement of 98.9dB. At 4v, the measurement is 98.44. There is roughly 0.46dB difference here, which isn’t bad considering the level is essentially going from 83dB at 1m to 96dB at 1m. Also, note the compression is minimal at Fs.

Conclusion

A nice looking tweeter, with some nice features when it comes to installation options for the car audio consumer.

A smooth FR with a rising response to help with off-axis response. If aimed on-axis, these may have to be tamed a bit on the 6khz to 8khz, depending on your tastes and goals. I’d personally like to see this tweeter without a rise and a bit more lift at 60 degrees off-axis to keep up with the other on/off axis measurements. However, it performs well on and off-axis as a whole and does a good job at extending the off-axis response rather than falling off sharply, so it’s not a huge knock.

The distortion parameters look pretty good. There is nothing outstanding to me as a limitation, based on my current understanding of transducer design and subjective experience. A crossover of >; 2.5khz is needed and you may be served well to cross a bit above this if you listen loud. With tweeters, I try to stay above 2.5khz even when the tweeter can handle going lower. YMMV (your mileage may vary).

Combining aesthetics, build quality and measured results, I’d recommend this tweeter. Overall, it performs well and allows you to use a larger dome tweeter in an area most domes of this size won’t fit thanks to the removable flange which I think is the major selling feature. Most 1″ dome tweeters require a decent area to install them in; the removable flange here knocks that real estate down by 16mm; more than 1/2 inch. This is very helpful to tight quarters installs.

Parting Notes

If anyone would like to offer some additional analysis, by all means, feel free to contact me and we will discuss the potential to add your own objective thoughts based on the data presented. This is a community effort and I want everyone’s understanding of what the data is expressing to grow.

If you like what you see here and would like to contribute to the fund toward additional test gear, hardware, or just buy me lunch, it would be greatly appreciated. Just click the “Contribute” button at the bottom of this page and contribute what you feel is worth it. Thanks.

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