www.audioexcite.com

This time I have the SB Acoustics SB15NRXC30-8 driver unit on the test bench. This is a 5” mid-woofer with a nice and sturdy build quality, especially considering its modest price of 55$.

Features:

• Vented cast aluminum chassis for optimum strength and low compression
• Proprietary cone material with natural fibers made in-house
• Soft low damping rubber surround for improved transient response
• Non-conducting fiber glass voice coil former for minimum damping
• Extended copper sleeve on pole piece for low inductance and low distortion
• CCAW voice coil for reduced moving mass
• Long life silver lead wires
• Vented pole piece for reduced compression

The mid-woofer has a 30.5mm voice-coil with a healthy 10mm (p-p) linear coil travel. It has a very low voice-coil inductance and is fitted with a copper sleeve on the pole piece to ensure a low distortion performance. At this price range, quite impressive features that SB Acoustics managed to fit into this mid-woofer.

T/S Parameters:

Preliminary data:

The four driver unit samples are from two different manufactoring batches. At this price range not much to complain about. Good consistency between the driver unit samples and it matches the official spec sheet reasonably well, with a higher Mms and lower sensitivity compared to official specs.

The mid-woofer has a low “fs” for its size and has a high mechanical Q-factor (Qms) and low mechanical loss (Rms), which ensures chances of good dynamic bass performance.

Impedance:

Preliminary data:

Note the very low inductance.  Impedance minimum of 6.3Ω @ 300Hz.

Frequency and distortion measurements will follow soon…..

I’ve published the ScanSpeak ”Beryllium” tweeter version of the Revelation Two – Monitor MkII loudspeaker design and the details can be found here:

Revelation Two – Monitor MkII BE

The two versions are similar, but the 600$ more expensive Beryllium version elevates the already very good sound quality a couple of notches.

Which of the two versions should you choose?

The textile dome version has better price/performance ratio, but if you are searching for the last few percent of better performance, slightly different tweeter character and isn’t price sensitive, go for the Beryllium version!

More details about the ScanSpeak “Textile” and “Beryllium” tweeter dome differences can be found here:

ScanSpeak Textile Dome vs Beryllium Dome!

Regards

/Göran

In this first blog post of the year I think I should give an update on what is going on at AudioExcite at the moment! 🙂

Revelation Two – Monitor MkII BE:

This is basically the “Beryllium” version of the Revelation Two – Monitor MkII. It’s almost finished. Some additional listening tests and tweaking are in progress and the most of the measurements are done, but of course the write-up and the publishing remains.

Sequence Three – Grand Reference:

This is my large 3-way reference build I’m working on since last summer. Besides the front grills it is almost cosmetically finished. I had it hooked up to my DEQX HDP-3 running it actively during the autumn to get a feeling of the driver’s capabilities and character.

Unfortunately I haven’t had as much time to engage in this build as I wanted, but finally during the Christmas holidays I’ve literally has done hundreds of frequency measurements and will as soon as I sorted them out, start some cross-over simulations.

Sequence Three – Grand Reference Construction!

 Satori mid-woofer MW16P-4:

I’ve done some measurements on this nice mid-woofer which can be read here:

SB Acoustics “Satori” MW16P-4

I’m now currently doing some cross-over simulations based on these measurements and it looks quite promising. The tweeters I’m thinking of using together with the Satori are these:

ScanSpeak D3004/602010
ScanSpeak R3004/602010

I haven’t yet decided which one of them to use, or both or something else. More simulations and perhaps listening tests remain before choosing.

Joachim Gerhard is using the same mid-woofer in a loudspeaker kit his doing for SB Acoustics and the build thread can be read here:

SB Acoustics Satori Monitor

And here:

SB Acoustics News!

Also, Jeff Bagby has done a very nice “transient perfect” design based around the Satori drivers and some details of it can be read in the same thread.

I’m not intending to build a copycat of either of these designs. My design based around the Satori mid-woofer will have another design and look to it and use different tweeters.

Wave guide test:

I’ve done some tests and measurements of a wave guide and combined it with four different tweeters I currently had available on the shelf. Some analysis remains and of course the write-up of it.

Waiting for new driver units to be delivered!

I’m very excited in a pair of driver units I’m waiting for to be delivered. I will not yet reveal what brand and model they are before I have them in my hands, but I can tell you that they are one of the world’s finest, in its genre.

These are not generally available to the public as DIY driver units and I’m not sure how much I will write about them in order not to unleash the wrath of the Manufacturer!!!

It looks like 2013 will be  an exciting DIY loudspeaker year! 🙂

Regards

/Göran

I wish you all a Merry Christmas and a Happy new Year!

Thank you all for your donations, interesting e-mails and encouraging support of the AudioExcite Loudspeaker Design website.

I have a lot of different loudspeaker designs, measurements and other stuff in the pipeline for the next year, but now it’s time to spend some quality time with the family for a couple of days. 🙂

Regards

/Göran

I’ve completed the measurements for the Satori MW16P-4 mid-woofer. This is the new mid-woofer “flagship” driver from SB Acostics and is clearly targeted to compete with the very best mid-woofer drivers from e.g. ScanSpeak Revelator and Illuminator series and perhaps drivers from AudioTechnology and Accuton etc.

My tested driver units are the 4 Ohm version of the Satori mid-woofer.

For detailed measurements see: SB Acoustics Satori MW16P-4

How does it stack up against the competition?

If we first look at the price for this driver, it costs 288$ which isn’t exactly the cheapest driver out there. Here is a price comparison of similar drivers that compete in the same class:

The Satori mid-woofer places it self somewhere in the middle of the price range, but to be honest it is also a slightly larger mid-woofer than the rest of the drivers on list. There aren’t many true 6.5” mid-woofers on the market today and on the list the Accuton driver is the closest match.

If we increase the size to about 7”, which is the most common size today the comparison fails a bit since with this driver size we seldom can use them up to about 3kHz, as in the case of the Satori.

If we look at the technical aspect of the Satori mid-woofer and to sum-up its key performance features, we have the following:

• A low resonance frequency of 29Hz out of the box without any burn-in.
• A large linear excursion capability of +/- 6mm.
• A very low inductance.
• A very stiff cone without any severe cone break-ups.
• An extreme linear and extended frequency response up to 15kHz, on-axis.
• A low loss rubber surround with very low mechanical damping.
• A low mechanical noise from surround at higher excursions
• A high Qms and low Rms together with the properties of the surround, provides the possibility of a fast and dynamic bass response.
• A very low distortion profile throughout the mid-woofers usable range.
• A usable frequency range up to 3kHz and it allows the use of shallow sloped filters.
• A high sensitivity of approximately 90dB 2.83V/1m
• A low bass response from a relative small enclosure of 18-22 liters (34-35Hz @ -6dB)
• A good consistency between the two tested driver unit samples.

Are there any cons? Yes, it has a modest spike of odd-order distortion and an elevated second-order distortion at the cone edge resonance.

I think this is an excellent top performer and worth its price compared to the competitors, but I haven’t yet subjectively listened to it in an actual loudspeaker design and I can’t tell if it is also high performer audibly, but it certainly has the potential to be a top sonic performer!

Right now I’m testing different tweeters to match the Satori and eventually there will be a “Satori Two – Monitor” design.

Regards

/Göran

On the test bench this time I’ve measured and compared two different compact sized tweeters from the ScanSpeak Illuminator series, the R3004/602010 and the D3004/602010.

For measurement details see:

ScanSpeak D3004/602010
ScanSpeak R3004/602010

These two tweeters are essentially the same tweeter. They share the same housing, face-plate and motor system. The “R” version is the ring dome version and the “D” version is the 1” textile dome version.

If we compare the two tweeter versions they differ as follows:

R3004/602010

• Ring dome diaphragm
• Phase plug design
• 5.6cm² effective piston area.
• 2dB lower sensitivity than the “D” version.
• More linear on-axis frequency response (<30deg off-axis).
• Slightly higher distortion than the “D” version.
• Costs about 35$ more than the “D” version.
  

D3004/602010

• 1” textile dome diaphragm
• 7cm² effective piston area.
• 2dB higher sensitivity than the “R” version.
• Better off-axis frequency response (>30deg off-axis).
• Slightly lower distortion than the “R” version.

(click on picture to zoom)

Blue = “R” version

Green= “D” version

If we look at and compare the tweeters impedance response, we see that they are almost identical. The “D” version has about 0.2 Ohm higher impedance than the “R” version.

(click on picture to zoom)

Blue = “R” version

Red = “D” version

Upper Left: On-axis @ 1m

Upper Right: 15deg off-axis @ 1m

Middle Left: 22.5deg off-axis @ 1m

Middle Right: 30deg off-axis @ 1m

Lower Left: 45deg off-axis @ 1m

Lower Right: 60deg off-axis @ 1m

If we look at the frequency response graphs, we can see that the “R” version has a very linear frequency response (+/- 1dB 2-20kHz) on-axis and up to 30deg off-axis. The “D” version has better off-axis dispersion above 30deg off-axis.

(click on picture to zoom)

R3004/602010

Blue = With protective grill

Red = Without protective grill

For those who doesn’t like the look of the protective grill, it’s safe to remove it since it doesn’t affect the performance at all. It’s very easy to remove and re-attach the grill as needed without breaking it.

Sum-up:

Which one to choose? That’s hard to say without subjectively listened to both of them in a loudspeaker design. Based purely on the measurements I would say that the “D” version has better price/performance ratio than the “R” version.

If you value pretty looking frequency response graphs or need extreme tweeter linearity on-axis, doesn’t need the extra sensitivity and isn’t price sensitive, go for the “R” version.

Finally I’ve found some time to publish the Revelation Two – Monitor MkII loudspeaker. Actually it has been more or less finished for some time now, but other things have come in between like work and some family quality time! 🙂

The Revelation Two – Monitor MkII loudspeaker uses two of my favorite driver units, the ScanSpeak 15W/4531G00 mid-woofer and the ScanSpeak D3004/660000 tweeter. Even though these drivers are quite expensive, I think they are worth its price and they deliver top notch sonic performance.

The ScanSpeak 15W/4531G00 is one of the smoothest driver I’ve ever measured and is completely without any nasty cone break-ups and it’s very well suited for shallow sloped filters like the second-order Linkwitz-Riley I’ve used in this design.

The D3004/660000 tweeter has a low distortion profile and is also a perfect match for the second-order cross-over filter I’ve used in this design.

I’m a fan of non-complex cross-over filters and I cannot say that this cross-over is simple if I count the filter parts needed for it, but it isn’t really that complex as it may look like at the first glance.

The mid-woofer cross-over uses a couple of response shaping circuits and the tweeter uses a “Ladder Delay Network” circuit to time delays the tweeter so its acoustic center off-set matches the mid-woofer and makes a perfect phase behavior around the cross-over frequency with minimal phase distortion.

Besides that the cross-over is very simple with a first order filter for the mid-woofer and a second order for the tweeter together with a LCR circuit to flatten the impedance peak at the tweeters resonance frequency.

The loudspeaker can be built using two different enclosure volumes and port tunings, 11 liter or 14 liter enclosure. One thing to remember is that the baffle dimensions and driver unit layout must remain the same in both options. Build the larger enclosure by making it deeper in order to accommodate the needed extra 3 liters.

In the published design I’ve used the Parts Express 11 liter curved enclosure, which works well and looks great. Both enclosure options have great bass response. In this design I personally prefer the smaller enclosure due to its quicker mid-bass response. The larger one is an option for those who want to dig a few Hz lower.

I’m very happy with the end result and in this design I think managed to use both these very fine drivers to its full potential. I might also if anyone whishes release a “Beryllium” tweeter variant using the very nice ScanSpeak D3004/664000 tweeter?

For further details see: Revelation Two – Monitor MkII

Regards

/Göran

Today I celebrate AudioExcite’s first year as a DIY loudspeaker  website. 🙂

First I want to thank all the readers for inspiring me to continue the work. I get a lot of interesting e-mails, which encourage me to continue. The website visits continues to grow steadily.

During this first year I’ve published six loudspeaker designs, done some driver unit testing’s as well as a loudspeaker review. I hope to be able to continue unabated, but I’m more of a technical, rather than a writer guy and publishing material is actually very time consuming. In the future I also want to publish more equipment reviews as well as driver unit measurements and HiFi show reports.

As always I have a lot of future ideas and plans for new loudspeaker designs. Currently I’m working with the large 3-way “Sequence Three – Grand Reference” loudspeaker. The construction continues as planned and I currently evaluate and listen to them with my DEQX pre-amp, crossed-over actively.

So far I like what I hear, but I think the mid-range/tweeter cross-over will be a challenge to get right. Currently I’m using a phase linear 48dB/octave cross-over with speaker correction. It’s crossed-over at 350Hz between the woofer and mid-range and  I’m testing different cross-over frequencies between 2.5-3kHz for the mid-range/tweeter. Currently I like the lower cross-over setup, but time will tell what I end up with.

Before I start the passive cross-over design I need to do some extensive measurements in order to begin the cross-over simulations. This loudspeaker is not the easiest loudspeaker to measure, since it’s so large and heavy. Without cross-over it weighs about 55kg each. Hopefully the new set of measurements will be done during the Christmas holidays.

Another design that’s in the pipe-line is the “Revelation Two – Monitor MkII” The MkII version uses the ScanSpeak D3004/660000 AirCirc tweeter instead of the “HDS” tweeter as well as a different cross-over topology. This setup brings the Revelation Two – Monitor to a new higher level of sonic performance. As soon as I’ve done the write-up it will be published.

Left: “Revelation Two – Monitor MkII”

Right: “Revelation Two – Monitor MkII” with “Beryllium” tweeter option.

Best regards

/Göran

These new driver units arrived at my door step! 🙂

It’s the new mid-woofer from SB Acoustics more exclusive series “Satori”. Satori in Japanese is a Zen Buddhist term for enlightenment. The word literally means “awakening”, “comprehension” and understanding”. The Satori drivers are designed for subtlety and realism.

My driver samples are the MW16P-4, which is the 4ohm version of the mid-woofer. The MW16P-8, 8ohm specification can be found here: MW16P-8. The driver has a very nice looks and build quality. The small but yet powerful neodymium magnet together with the shape of the chassis contributes to an optimal airflow behavior.

To sum-up the Satori mid-woofer features:

• Vented aerodynamic cast aluminum chassis for optimum strength and low compression
• Proprietary cone material with EGYPTIAN PAPYRUSTM fibres made in-house
• Soft low damping rubber surround for optimum transient response
• Advanced BIMAX spider for improved linearity
• Powerful optimized low distortion neodymium motor system
• Non-conducting fibre glass voice coil former for minimum damping
• Extended copper sleeve on pole piece for low inductance and reduced distortion
• CCAW voice coil for reduced moving mass
• Long life silver lead wires attached 180° apart for improved stability
• Vented pole piece for reduced compression
• High piston to chassis diameter ratio
• Gasket and bolt hole protrusions for reduced coupling to speaker cabinet

Preliminary T/S parameters measurements:

With >90dB @ 2.83v/1m, the 4ohm version is a fairly efficient mid-woofer. It’s most likely to achieve a system sensitivity of about 86-87dB @ 2.83v/1m, when the right amount of “baffle Step Compensation” is applied. Nice consistency between the two driver unit samples. About 25% higher Mms compared to the official spec sheet for the 8ohm version.

Preliminary Impedance measurements:

(click on picture to zoom)

Left: Free-air impedance sample 1 vs. sample 2.
Right: Close-up of free-air impedance sample 1 vs. sample 2.

A very sharp and narrow impedance peak at the resonance frequency of the driver unit, which indicates a mid-woofer with low mechanical losses. The edge resonance occurs somewhere between 1-1.2kHz and will most likely give a hole in the frequency response and some elevated 2nd order harmonics at the same frequencies. From the impedance measurements, cone break-ups are visible at about 4kHz and 6kHz. How severe these break-ups are to be determined in the frequency and distortion measurements.

This mid-woofer should be able to be used up to about 3kHz, but some frequency and distortion measurements analysis remains to be certain.

 Preliminary Box Simulation:

This is a versatile mid-woofer that would work in an enclosure anything between 18-22 liters. A text book QB3 alignment gives an 18 liter enclosure, but even a 14 liter would work with some elevated mid-bass response. With its +/- 6mm linear x-max, this mid-woofer has the potential to produce some serious bass considering its size.

The question is what kind of tweeter to combine the Satori mid-woofer with? 🙂

A small picture update of the current build status!

In “real life” the loudspeaker looks darker than shown in the pictures. Minor “finishing” adjustments remains as well as building some front covers for the loudspeaker.