Acoustic Reality Serial Crossover

The Capacitor-less Serial Crossover

The new crossover invention was published on Internet forums to prevent other manufacturers to patent our invention.

Shareware - Help to promote it.
Help to promote the AR-SXO and help to prevent others to patent our invention. One person has already tried to make a patent on our Invention, but failed, because we have shown our invention on the Internet.

Feel free to use the very different AR-SXO. It is royalty FREE, but if you are using the AR-SXO: Please add an URL link to the http://www.Acoustic-Reality.com website, that's all we are asking for. If you don't have a website, then you can not make a link on your none-existing website.
How to use the AR-SXO in commercial sold speakers:
Feel free to use it. Speaker manufacturers or other commercial facilities (DIY stores and more), which are using the AR-SXO topology or ideas from the topology or the method to find the component values or selling components to the topology, must add an URL link to the http://www.Acoustic-Reality.com website too. That's all. We do not sell any DIY parts and therefore we do not steal your customers.

The impedance linear crossover to most fastidious audiophiles is here:
Make the capacitor-less version of the Acoustic Reality Crossover
with only three distortion-free components !

Listening Impressions

(Morawski) The sound is so smooth you positively cannot hear the transition from lows to highs. The bass is extremely solid and well controlled. The mids are lush but clear and the highs are detailed, airy, and delicate without a hint of brightness.
(Ken L.) How's the sound? A very big improvement, I believe eliminating the electronic xo played a larger part in the improvement. I am hearing things in the high frequencies that I did not know were there. Bells and cymbals are crisp and clear. Information that is down in level is easily heard.

(EdM) Trust me, you will never hear a better crossover at any cost.

(Yair) Regarding sound the sound is very good indeed, never though it can be done with so few parts!

(Jacq) Simply said, it is the best it ever sounded crossover.

(Scorpio) Sound? Far better than original! More details, no sharpness, no rough SSS but still no dull sound, much bigger soundstage.....I'm amazed!!

(John P.) I'm a musician and have been building speakers for 25 years. The first thing that struck me was how well the drivers blended. For this combination just guessing at the values the difference was night and day. I'm very impressed.

(Ken P.) They sound pretty damn good.

(Mike F.) The female vocalists were IMO spot-on (good information retrieval with no snaky SSSSSSS's). The end result is indeed beautiful music.

(Dave) I have been designing recording studios and (repeating) crossovers for 37 years or so. More air, dynamics and "they are here" going on.

(Andy G.) With any of the normal series x-os I tried (without that huge LRC trap) there was a definite harshness/grittiness ? round about that frequency, the pillow test indicated it was definitely from the XT25, with the ARS XO that just doesn't exist. I am now COMPLETELY HAPPY with the result.

(Al J.) I'm an audiophile for about 20 years now but your filter (without C) has amazed me like nothing before...... it was as if I heard my tweeter for the very first time! Although it is a very well known type (scanspeak 9300), it suddenly showed its qualities.

(Kevin W.) And damn, am I impressed!! The sound is so much more open, airy, and detailed. It's very much like listening to electrostatic speakers. The imaging... wow. Makes me want to stop typing and go out and listen some more. Hehe, anybody want to try this crossover? You'll be pleasantly surprised!

 
The position of L2 and the mid/bass unit can be swapped - same function.
The position of R1 and C1 can be swapped - same function.


C1 can be removed, but requires R1 is a high power resistor.
In case C1 is removed the impedance is:
Zspeaker = R1 // Zbass

Precise formula (but not necessary) :
Zspeaker = (1 / (1 / R1 + (1 / Zbass) + ZL2))) + (1 / (ZL1 + 1 / Ztweeter))

A part of my patent claims (which was never posted to the Danish PTO) is that the simple network can be extended to handle 12dB, 18dB, 24dB electrical slopes. How?

Higher order slopes:
- Insert a capacitor in series to the tweeter.
- Insert a capacitor in parallel to the woofer
- Insert a capacitor in series to the tweeter and an extra coil in parallel to the tweeter.
- Insert a capacitor in parallel to the woofer an extra series coil to the woofer too.

Zobel and Notch filters can be added in parallel to the woofer too. Therefore you can control the impedance of the woofer without affecting the response and impedance to the tweeter.

When you insert a series capacitor to the tweeter you can also add notch and zobel to the tweeter without affecting the response and impedance to the woofer.

As you may have found out this crossover is as easy to calculate and handle as the parallel topology crossover, but without damaging correction network to make the speaker impedance linear.

It is very simple to set up formulas to make frequency response calculations, impedance calculations and plots. Soon I will make a program to run on this website. Then you can calculate the crossover frequency and the baffle compensation on this website, but nothing is as good as listening tests and measurements!
The Acoustic Reality Crossover Network is only a frequency depended voltage attenuation without a lot of damaging crossover components - it is a minimalist crossover network having a lot of features!

We would like to point out that adding a lot of components is not good to the sound, especially not capacitors. Keep the crossover as simple as possible and use better loudspeaker driver units. It is much easier to make a good speaker using good quality driver units. Then you can make the Acoustic Reality crossover using only one high quality resistor and two high quality coils.

80% of the energy from music is found in the bass frequency area. We do ONLY suggest to remove the capacitor in DIY projects, because you will burn off 40% of extra energy in the resistor.

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The difference compared to existing series crossovers is the method the component values are selected to make it impedance linear and to get control of the crossover point, while being able to re-configure the crossover to an impedance linear parallel crossover using the same component values for bi-amplify.

It is ordinary that series crossovers have a +3dB peak in the crossover point, but the AR-SXO crossover can be tuned to have a completely flat frequency response in the crossover point too or said: Each unit can be controlled to meet -6dB in the crossover point, which results in a completely flat frequency response in the crossover point.

It is less ordinary to see impedance linear series crossovers. However, this problem is also solved by the Acoustic Reality Series Crossover; it is impedance linear in the crossover point.

It is less ordinary to see series crossovers with baffle compensation without adding extra components. Select a big value L2 coil and the baffle compensation problem is solved.

It is also possible to extent the new crossover to a very simple multi-way impedance linear crossover. The crossover is implemented by only using three or four components and has several advantages when considering the very few number of components, both the impedance and the frequency response is linear and can be re-configured to a parallel impedance linear crossover using the same component values. If the capacitor C1 is removed the crossover is capacitor-less, but the disadvantage is that the impedance will drop to approx. the half value of the resistor, R1, in the bass area. Therefore the resistor must be able to handle high power. It is very easy to set up the crossover to any loudspeaker when using quality driver units. CLICK HERE to see a multi-way example. Several methods can be used to make a multi-way crossover design and we will make more examples.

Thank you very much to John Kreskovsky, who has done a tremendous work to validate the crossover. You should that the tweeter unit, which is used in the study, is not of the same quality found in the Acoustic Reality loudspeakers. You should also note, that we are using a lower L1 value to protect the tweeter better and our fine-tuning is based on interactions between listening tests and acoustical measurements.
CLICK HERE to see the Acoustic Reality Crossover Study published by the IEEE author and Scientist John Kreskovsky.
CLICK HERE to see his study when the capacitor is removed. Note: We did use this circuit before John K. did validate this crossover too, it was a part of our claims. When the Capacitor C1 is removed the impedance is like most speakers from Sonus Faber, but if using the same drivers the series crossover is more open and has a better sound too. Now it is up to you which sound you do prefer.

We prefer a lower value; L1 = 0.1mH should be used, the DCR of the coil must be as small as possible too.

The sound of the new crossover is musical, more transparent and more open.

Here are some impedance measurements when the crossover is used in the AVinci Studio:
CLICK HERE to see the AVinci Studio with C1.
CLICK HERE to see the AVinci Studio without C1.
CLICK HERE to see the AVinci Studio with and without C1.

A capacitor is not distortion free. Therefore you must use a very good capacitor. Else remove it and the crossover is free of component distortion (only when using air coils too), but in case you don't use the capacitor in YOUR crossover design you really have to know what you are doing. The DCR of the L1 coil must be as small as possible too. It is also important to use a very high power resistor when the capacitor is removed you should use a 100W power resistor. When the capacitor is used, then a 20W power resistor should be enough on most 2-way speakers.

You should also note that our speakers are delivered without jumpers, but the jumpers are in the shipping box. Now it is up to you to make the speakers capacitor-less. How to do? Add the jumpers.

CLICK HERE to see some other examples, with or without capacitor, with or without special baffle compensation. Note: It is not necessary to add the extra coil to make baffle compensation. A big value L2 coil is enough.

Higher order crossover:
You can insert a capacitor in series to the tweeter and connect a capacitor in parallel to the woofer too, but requires measurement equipment to adjust for a flat frequency response However, the impedance is still linear in the crossover point and should not be necessary when using very high quality driver units (Use for example Scan Speak drivers. They are great performers to the price).

Initial values to DIY: With C1 (we do recommend to use C1 to DIY projects):
L1=0.1mH
R1=6.8ohm
L2=1.5mH
C1=22uF

Adjust R1 and L2.
R1 should NEVER be less than 3.9ohm with C1 mounted.
The value of L2 depends of how much baffle compensation and how much bass you prefer.

Without C1 :
L1=0.1mH
R1=8.2ohm
L2=1.5mH

Adjust R1 and L2.
R1 should NEVER be less than 6.2ohm without C1 mounted.
The value of L2 depends of how much baffle compensation and how much bass you prefer.

How to fine-tune the ARsxo yourself

Here are some rules of how to find the values of the ARsxo only using listening tests.

1.
L1 should always be 0.11mH - it does work on almost all tweeters, including ribbons working in from 2kHz and up.

2.
You need two coils each stereo speaker, initial values to find the correct values.
- 1mH
- 1.8mH.
Connect L2= 1.8mH in series to the bass unit, nothing else. If the sound is too compressed and there is too much bass on moderate volume level, then try 1mH. If you feel there is still too less midrange, then you have to go down in value, but remember you are not using the tweeter, not yet.

3.
You need six cheap resistors each speaker - 5Watt or 10Watt - only to find the value, 3,9ohm, 4.7ohm, 5.6ohm, 6.8ohm, 8.2ohm, 10ohm Now you are using the value of L2 that you did find in step 2. Try all resistors and listen, start with 6.8ohm. You have to set up a pair of stereo speakers.

4.
Fine-tune L2 and R1. May be L2 should be bigger than 1.8mH or a smaller than 1mH. If you need more bass, then use a bigger value L2 or reduce the value of R1. If you need less bass, then reduce the value of L2 or increase the value of R1. It is always best to keep the R1 as high as possible. It will let your amplifier an easier handle the load of the speakers (and therefore less distortion).

Important: Change the low power resistor to a high power resistor, 50W or more. If you don't want to burn off 40% of the energy in the R1 resistor then insert a 27uF good quality capacitor. Now you have a crossover.