Category: ‘Blog’

Hifi Show Report!

March 8, 2014 Posted by gornir

 

I visited the High End Mässan 2014 HiFi Show last month and some pictures and comments can be read here:

HighEnd Stockholm 2014

Regards

/Göran

Satori Two – Monitor Construction Released!

January 3, 2014 Posted by gornir

 

SONY DSC

 

It´s time to publish the first AudioExcite loudspeaker design this year!

To the left in the above picture we have the new Satori Two – Monitor besides the “Sequence Three – Grand Reference” loudspeaker.

The Satori Two – Monitor is a large sized stand-mount loudspeaker and is based around the SB Acoustics Satori mid-woofer.

The Satori mid-woofer is a well behaved very nice sounding driver that sets a new standard for high-end drivers in its size. The 6.5” mid-woofer size fills a gap where it’s hard to find equivalent drivers today.

Either they are larger 7” mid-woofers, which are great in the bass department, but often lacks mid-range refinement and need to be crossed over below 2kHz. Or they are smaller 5-5.5” mid-woofers that are great in the mid-range, but struggles in the low bass department.

The Satori driver fills that gap with honor!

First, I planned to release the Satori Two – Monitor with two different tweeter options, the ScanSpeak R3004/602010 and the D3004/602010, but in the end the “D” version blended more nicely with the Satori mid-woofer and was sonically better than the “R” version.

That doesn’t mean that the “R” version tweeter isn’t any good, but it simply isn’t good enough in this configuration.

A comparison between the two tweeters can be found here: ScanSpeak Illuminator Tweeter Measurements!

For the Satori Two – Monitor construction details see: Satori Two – Monitor

 

Later this spring, I will build a pair of nice looking matching front covers for them!

 

Regards

/Göran

Fountek NeoCD3.5H Measurements!

December 22, 2013 Posted by gornir

neocd35-1neocd35-3

 

The Fountek NeoCD3.5H is a horn-loaded low priced ribbon tweeter with great frequency response and sonic performance.

I’ve used the NeoCD3.5H both in conventional 2-way monitor designs and in 2-way M-T-M designs with great success.

As many small sized ribbons the distortion profile is rather high, but if the cross-over frequency and filter topology is carefully chosen the NeoCD3.5H is a nice sounding affordable ribbon tweeter.

For detailed measurements see: Fountek NeoCD3.5H

SB Acoustics Mid-woofer Measurements!

December 20, 2013 Posted by gornir


(click on picture to zoom)

Left: SB15MFC30-4
Right: SB15NRXC30-4

Here’s a new set of measurements!

This time I’ve tested a pair of SB Acoustics 4Ω mid-woofers. The main difference between the two drivers is the cone material used. The SB15MFC30-4 uses a mineral filled Polypropylene (PP) cone and the SB15NRXC30-4 uses a coated Papyrus fiber cone.

They both share all other features like the same type of chassis, voice-coil, surround and motor system etc.

They are more alike than different in its measurement performance and it will be interesting to see if they subjectively sounds different from each other.

Detailed measurement data:

SB Acoustics SB15MFC30-4
SB Acoustics SB15NRXC30-4

SB15MFC30-4 vs. SB15NRXC30-4 comparison:

 

Build quality and looks:

At a first glance they both look confusingly similar to each other. The SB15MFC30-4 with its Polypropylene cone is slightly darker and shiny in its color compared to the coated structure of the SB15NRXC30-4.

They both have an impressive build quality with a high performance/price ratio.

Impedance:

 

Imp 1L SB15MFC30 vs SB15NRXC30

(click on picture to zoom)

Green = SB15MFC30-4
Blue = SB15NRXC30-4

They have  almost identical impedance plots besides the difference in the impedance peak of the resonance frequency (Fs).

Frequency:

 

Freq 0deg 1L SB15MFC30 vs SB15NRXC30Freq 15deg 1L SB15MFC30 vs SB15NRXC30

(click on picture to zoom)

Left: On-axis
Right: 15deg off-axis

Blue = SB15MFC30-4
Red = SB15NRXC30-4

They have almost the same frequency response in the mid-range. The PP cone of the SB15MFC30-4 rolls of a bit earlier than the SB15NRXC30-4, but they both have a very extended frequency response.

Distortion:

 

SB15MFC30-4-1L -- 15cm 95dbSB15NRXC30-4-1L -- 15cm 95db

(click on picture to zoom)

95dB @ 1m

Left = SB15MFC30-4
Right = SB15NRXC30-4

The SB15MFC30-4 has slightly higher odd-order distortion, but they are both good performers in this price class. When a proper cross-over design is in place, the difference should be negligible.

Summary:

 

These two mid-woofers are more alike than different from each other and it will be interesting to see how they sonically differ.

Based on the measurements performance I consider both these mid-woofer to be of high value and with a high performance/price ratio.

SB Acoustics Tweeter Measurements!

December 8, 2013 Posted by gornir

SB26STAC-C000-4_1SB26STCN-C000-4_1

These two SB Acoustics tweeters are the first in a series of new driver measurements I will publish on the website. I will probably use some of them in future moderately priced loudspeaker designs.

Detailed measurement data:

SB Acoustics SB26STAC-C000-4
SB Acoustics SB26STCN-C000-4

SB26STAC vs. SB26STCN comparison:

 

Build quality and looks:

The SB26STAC with its aluminium faceplates both looks and feels more robust than the SB26STCN plastic faceplate and its small Neodymium magnet. At this price level, 44$ for the SB26STAC and 35$ for the SB26STCN, they both seem to be very nicely built.

Impedance:

 

Imp 1L SB26STAC vs SB26STCN

(click on picture to zoom)

Green = SB26STAC
Blue = SB26STCN

The SB26STAC has a resonance frequency of 750Hz and the SB26STCN about 170Hz at 920Hz. Both are very close to the manufacturer specification. The Impedance profile is very similar from 2.5kHz and up.

Frequency:

 

Freq 0deg 2R SB26STAC vs SB26STCNFreq 15deg 2R SB26STAC vs SB26STCN

(click on picture to zoom)

Left: On-axis
Right: 15deg off-axis

Blue = SB26STAC
Red = SB26STCN

Note! SPL is normalized to roughly the same sensitivity

The tweeters have almost identical frequency response curves. The SB26STCN has about 0.5-1dB higher sensitivity than the SB26STAC.

Distortion:

 

SB26STAC-C000-4-2R -- 10cm 95dbSB26STCN-C000-4-2R -- 10cm 95db

(click on picture to zoom)

95dB @ 1m

Left = SB26STAC
Right = SB26STCN

The SB26STAC has lower distortion than the SB26STCN. A qualified guess is that the SB26STAC can be crossed over lower, at least 500Hz or more than the SB26STCN.

Summary:

 

The SB26STAC would fit nicely with mid-woofers up to 6.5” and the SB26STCN would fit nicely in M-T-M configurations or in small compact mini monitors with a mid-woofer size up to 5”

Based on the measurements performance I consider both these tweeters to be of high value and with a high performance/price ratio. It will be interesting to see if they also sonically turn out to be as good as the measurements.

Satori Two – Monitor Prototype!

November 10, 2013 Posted by gornir


Sorry for the poor picture quality!

Satori Two – Monitor Prototype!

Satori Two – Monitor is the current project I’m working on. The pictures show the unpainted prototype baffle that’s on the test bench.  As you can see in the pictures a stepped baffle is used in order to compensate for the tweeter and the mid-woofers relative acoustic center off-sets.

The cross-over prototype uses a shallow sloped LR2 (acoustical) filter, which electrically consist of a first order filter + a response shaping circuit for the mid-woofer and a second-order filter + a response shaping circuit for the tweeter.

Two different ScanSpeak Illuminator tweeter options will be tested and can you read more about these two different tweeters here:

ScanSpeak Illuminator Tweeter Measurements!

I will soon start the prototype cross-over evaluation and listening tests.

Sequence Three – Grand Reference!

The Sequence Three – Grand Reference design is finished, but unfortunately I haven’t done final measurements and the write-up for publishing yet. I had a mishap with the RAAL ribbons where I accidently got a bad ground loop in one of my amplifiers due to a poorly fastened signal cable in combination with the RAALs connected with only a single cap. The RAAL ribbons are very robust and didn’t break completely, but the ribbon did get stretched. I haven’t yet succeeded to tighten them enough to be satisfied.

The loudspeaker sounds good, but not as great as they did before the mishap. I will once again try to tighten them, but in the end I might have to buy a new set of replacement ribbons before I make the final measurements for the write-up.

If you can’t wait for me to publish the finished Sequence Three – Grand Reference design and you are planning to build something similar, you can always contact me by mail by filling in the Contact Form and I will give you some cross-over details to get you started with the design.

Currently I also doing some extensive driver unit measurements on a series of modest priced tweeters and mid-woofers that I will use in future designs.

Regards

/Göran

Measurement Tools!

October 12, 2013 Posted by gornir

 

A while ago I bought the WT2 tester (Smith & Larson Audio) and I’ve started to explore its features and capabilities. I’ve used the WT3 tester (Dayton Audio) for a long time and after some discussion threads at diyAudio regarding the WT3 vs. WT2 capabilities I became interested in exploring and comparing the two.

Let me first point out that the WT2 and WT3 tester are different products. The WT3 tester isn’t a newer version of the WT2 tester, even if the name might give the impression of it.

Note! I have the original WT3 tester, not the newer “DATS” tester from (Dayton Audio)

 

WT2 WT3

Left: WT2 tester

Right: WT3 tester

Both testers are supplied with software, USB cable, measurement cable and a calibration resistor. The WT2 tester uses a 10 Ohm 1% tolerance resistor and the WT3 uses a 1k Ohm 1% tolerance resistor.

Note! I personally use a higher tolerance 10 Ohm 0.1% calibration resistor for all my measurements.

The WT3 tester has never caused any real issues or problems for me. It has been reliable, fast and easy to use. Some people have raised doubts that the WT3 tester doesn’t produce correct Q values in T/S measurements. This is partly true, but based on the impedance plot produced by the WT3 tester the Q values are correctly calculated. The question is however, can the impedance plot be of higher resolution and detail in order to get a more accurate Q value calculation?

The answer is yes. The WT2 tester does seem to have a better algorithm and accuracy in measuring the resonance frequency at low frequencies. Besides that the WT2 tester has a lot more features than the WT3 tester (I haven’t tested all yet), but it also has a higher price tag. I think the higher price tag is fair given its more extensive features.

Partly due to its simpler functions the WT3 tester is easier and more intuitive to use and compared to the WT2 tester the user interface is more clean and robust to use. The WT2 user interface feels a bit outdated and is more cumbersome to use. The window handling doesn’t feel so consistent in its behavior. This shouldn’t be read as criticism on the WT2 capabilities, rather as suggestions of hints to future improvements.

I haven’t yet tested and used all of the WT2 capabilities, but I have done some T/S parameter and impedance measurements to compare with similar tests on the WT3 tester.

 

Measurement setup:

WT2 tester (Smith & Larson Audio) v7.01
WT3 tester (Dayton Audio) v1.51b1

I’ve used a pair of high quality SB Accoustics Satori MW16P-4 mid-woofers and ScanSpeak Illuminator R3004/602010 tweeters with a high driver consistency for the measurement tests.

The “Delta mass” method is used for T/S parameters measurements and the Impedance plots are made with 344 measurement points for both the WT2 and WT3 tester. 344 measurement points is the setting the WT3 tester has and it cannot be changed. The frequency range is 1-20000Hz.

All drivers are measured “cold” without any e.g. suspension “massage” The WT2 and WT3 tester is calibrated with the same 10 Ohm precision (0.1%) calibration resistor.

The results are exported in the “zma” format and imported in to the WT3 tester for visual comparison.

 

Results:

Green = WT2 tester
Blue = WT3 tester

Impedance sweep:

MW16P-4 #1 WT2 vs WT3xMW16P-4 #2 WT2 vs WT3

(click on picture to zoom)

Left: Driver sample #1

Right: Driver sample #2

The pictures show the Satori MW16P-4 mid-woofer. We have some variation in the lower frequencies and above 10kHz, but between 100Hz and 10kHz the impedance plot is almost identical.

R3004-602010 #1 WT2 vs WT3xR3004-602010 #2 WT2 vs WT3x

(click on picture to zoom)

Left: Driver sample #1

Right: Driver sample #2

The pictures show the ScanSpeak R3004/602010 tweeter. The impedance around the resonance frequency is virtually identical. At higher frequencies starting at >5kHz we have some variation even though not a huge difference (about 0.18 Ohm @ 10kHz). Here the WT2 tester gives a result which appears to be closer to the manufacturer’s specification.

 

 T/S parameters:

MW16P-4 T-S WT2 vs WT3

The picture shows the T/S parameters for the Satori mid-woofer. Not surprisingly, we have some variations here as well. The differences aren’t huge, but the WT3 tester seems to consequently give a bit higher Qts values. This is confirmed by test measurements I’ve done on other random drivers I have. Here I think the WT2 tester measurement method and its more detailed measurement resolution contributes to a more accurate result.

 

R3004-602010 T-S WT2 vs WT3

The picture shows the T/S parameters for the ScanSpeak. Here at higher resonance frequencies the variations are negligible. The resonance frequency is within 0,13% and the Re is within 1.5% between the WT2 and WT3 tester.

 

Loudspeaker box simulation:

Box QB3 alignment WT2 vs WT3

The picture shows the differences in a text book QB3 box alignment calculated from LspCad Pro based on T/S parameters from SB Acoustics specification, WT2 tester and the WT3 tester. Here we obviously can see some differences due to the different box volumes and port tunings.

Box 19liter WT2 vs WT3

The picture shows the results using an enclosure with a volume of 19 liters, a port tuning of 38Hz and an added simulated filter coil resistance of 0.3 Ohm (Rg) based on T/S parameters from SB Acoustics specification, WT2 tester and the WT3 tester.

Ok, here we can see virtually the same response whether we used the manufacturer specification, the WT2 or the WT3 tester calculated T/S parameters.

 

Conclusion:

The WT2 tester does seem to be a bit more accurate in its T/S parameter and impedance measurements as well as featuring more functions than the WT3 tester. The WT3 tester however is simpler and faster to use and has a lower price tag than the WT2 tester.

As a comparison the WT3 tester does an impedance sweep in about 1.5 seconds. The WT2 tester takes about 8 minutes for the same impedance measurements setup (WT2 uses a Sine wave signal).

In real life, does it matter which one to choose for an accurate box design calculation or cross-over filter design?

In my opinion no not really, but if you want perfection for the T/S parameter calculation and the added features, go for the WT2 tester. If you don’t find the T/S parameter accuracy and the added features of the WT2 are the most important and prefers fast and simple measurements almost equally good for cross-over design, go for the WT3 tester.

I personally think both the WT2 and WT3 tester are nice tools and I will in the future use both where it’s applicable.

In the next loudspeaker project I will use both tools and compare if the impedance plots have any impact on the final design results.

The summer is almost over!

August 31, 2013 Posted by gornir

 

The summer is nearing its end and the autumn is soon here and it’s time for a short blog update!

For once, the summer weather has been wonderful in Sweden and I’ve had a nice relaxing time with the family. We traveled to Germany, France and Spain during the vacation and among other things, we visited vineyards and enjoyed a lot of delicious food and wines. :-)

This summer, there hasn’t been much loudspeaker building, but I have been working on some custom built enclosures and baffles for the upcoming “Satori Two – Monitor” design.

The plan for the autumn and winter is to finish the “Sequence Three – Grand Reference” design which unfortunately has been paused for a long time due to time shortages and of course to finish the above mentioned “Satori Two – Monitor” design.

I have also bought a bunch of nice quality tweeters and mid-woofers in the lower price segment and I will evaluate them, measure them and publish the results during the autumn. Some of them will hopefully end up in some nice two-way monitor designs and possibly in a small slim 3-way floor-stander.

Regards

/Göran

Concentric Three – M5 Construction Released!

July 18, 2013 Posted by gornir

 

It has been a long time since my last Blog update, since I’ve been busy and haven’t had much time over to update the website, but you can rest assure that I haven’t given up! ;-)

 

 

Finally I have published the Concentric Three – M5 design. It has actually been finished for some time now and I enjoy and like it very much.

If comparing with the commercial KEF loudspeakers, the Concentric Three – M5 speaker most closely resembles the 2600$ KEF R500 design in size and driver unit layout.

The KEF SP1632 co-axial driver is truly an amazing driver and delivers top notch performance to a budget price.

I have a couple of times listened on the KEF R500 and they instantly caught my interest, but I haven’t actually listened to my design side by side with the KEF R500 so I can’t comment on the exact sonic differences between them.

One thing I can say is that as a DIY designer I don’t have to compromise with the cross-over design in order to cut costs as most commercial loudspeaker manufacturer have to do, at least in this loudspeaker price range.

It would however be interesting if anyone out there has the cross-over schematics for the KEF SP1632 driver used in the KEF loudspeaker “R series” in order to compare the design choices made.

If you do please let me know!

For further details on my design see: Concentric Three – M5

Concentric Three – M5 Construction Update 1!

April 27, 2013 Posted by gornir

 

I’ve now finished the cross-over simulation and I’m moving on to the next stage of building the first cross-over prototype and starting the listening tests.

The cross-over:

(click on picture to zoom)

 

The cross-over is very simple and uses a LR4 filter topology (acoustical) between the tweeter and mid and a LR2 topology (acoustical) between the mid and woofer. The cross-over consist of only 12 parts and all sections are second-order electrically, besides the tweeter section which is third-order electrically in order to achieve an acoustical LR4 frequency roll-off.

Note! The woofer’s are connected with reverse polarity.

The tweeter level can be adjusted by changing the value of the single resistor R1. R2 and R3 can be replaced with one resistor if it can handle >20W.

I don’t reveal the actual component values until I’ve evaluated the cross-over prototype. The cross-over schematic is only used here to inform how the cross-over looks like. Depending on the listening tests and further measurements it can be changed little or completely.

 

Frequency response simulation:

As in most of my designs the cross-over is optimized from the 15deg off-axis measurements and thus, the loudspeaker is intended to be used with none or little toe-in when setup.

Using the 15deg off-axis measurement generally means that you have a less pronounced baffle diffraction influence in the frequency response when optimizing the cross-over. Generally I’m optimizing the speaker cross-over to have equally good phase behavior between 15-30deg off-axis frequency response, rather than having a good phase response at the on-axis measurement and a deteriorating phase behavior as you go off-axis.

When optimizing around the 15deg off-axis measurements, the on-axis frequency response tends to be a little “hot” in the mid and upper treble. By using the appropriate amount of toe-in, I think this slightly added frequency response gives a more presence and airiness to the sound and are usually beneficial and desired.

However, each design and the drivers used in it are unique and sometimes it might not work out properly. The cross-over simulations and measurements alone doesn’t tell if it’s good or not and I consider this and the tweeter level adjustments to be the voicing and fine tuning part of the loudspeaker design.

 

(click on picture to zoom)

Left: 15deg off-xis frequency response (no smoothing applied).

Right: 15deg off-xis frequency response with mid-range reverse polarity.

The mid-range driver has a built in “BBC” response dip between 2-3.5kHz. The tweeter has a very extended and smooth frequency response, especially considering that this is a co-axial driver unit. The loudspeaker has a system sensitivity of about 88dB @ 2.83v/1m.

When reversing the mid-range polarity we can see very deep notches around 590Hz and 2.8kHz at the cross-over frequencies. The deep notches indicate a very good phase response tracking and summation between the driver units around the cross-over frequency.

 

(click on picture to zoom)

Left: Frequency response 0-60deg (no smoothing applied).

Right: The frequency response curve is an average of four measurements (blue): on-axis, 15, 22.5 & 30deg and six measurements (red): on-axis, 15, 22.5, 30, 45 & 60deg.

The loudspeaker has a smooth power response with a slightly downwards tilting response at higher frequencies. The tweeter has an extended frequency response with very wide off-axis dispersion.

 

(click on picture to zoom)

Left: Four different tweeter levels.

Right: System impedance simulation

The resistor R1 can be changed to fine tune the tweeter level. The level 2 is the “reference” level used in the above frequency and cross-over simulations. The minimum impedance occurs @ 120Hz and is slightly below 3 Ohms. The system sensitivity of 88dB @ 2.83v/1m is mainly achieved by the low impedance driver units used in the loudspeaker. A 4 Ohm stable amplifier is recommended.

 

Summation:

As I said before, I don’t intend to make a clone of any of KEF’s loudspeakers and I don’t have a clue how the cross-over for KEF’s loudspeakers looks like, even though my chosen cross-over frequencies seems rather similar to those used in the R500 loudspeaker. It just happens to be very suitable frequencies to cross-over at. I would say that a suitable cross-over window is about +/- 100Hz from that I have chosen, at least the drivers seems to be engineered in that way.

With that said, the KEF driver is really great and I’m eagerly waiting for the cross-over components I’ve ordered for the first prototype and I can’t wait to have a listen to the Concentric Three – M5 loudspeaker! :-)

For further details of the driver unit measurements see:

“KEF SP1632″

“SB Acoustics SB15NRXC30-8″

The KEF R500 loudspeaker using the same mid/tweeter and similar sized woofer’s:

“KEF R500″

Independent KEF R500 loudspeaker measurements:

“KEF R500 Measurements!”