1 Topic by rynogee (edited by rynogee 2023-10-22 06:26:10)

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Topic: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

I have read some very informative posts on subwoofer integration for the ADI-2 DAC, but have a slightly different question I'd like help with. I'm yet to buy my ADI-2 DAC but am fairly sure it is the one, and am also yet to buy my subwoofers (the more difficult part).

I have Acoustic Energy AE1 active speakers. I want to run a stereo pair of subwoofers with them. My use case is only music, small-modest size home office room. Want deep but high quality bass (lots of electronic music). Haven't tested/analysed the room yet.

I was thinking to run the subs on the DAC RCA out, and AE1s on the XLRs, which gives me many many options for subs, but maybe not the best or easiest integration (depending on the sub) and risks ground loops.

It was suggested I should run everything on XLR / balanced, from DAC to subs, then to AE1s. This is interesting but limits the number of subs to choose from. Also have to consider if the sub has HPF or not. But maybe integration of the subs with speakers is easier in this case?

This led me to wondering about the value of having DSP (and PEQ) on the sub I choose. If I use the RCA out I can have subs like SVS with DSP & EQ etc to manage system integration and do some room correction. But to get DSP and EQ, and the XLR balanced inputs and outputs on the same sub seems like it is going to cost a lot more than I want to spend.

I ask all this because of the EQ features on the ADI-2 DAC, and my need to better understand what problem(s) it can solve, so I don't buy the wrong subs (e.g. buy more features on the subs that I don't actually need for good system integration and for room correction).

I am assuming I would do room correction with REW and a mic (or a similar solution), which can be achieved for the whole system with the EQ in the ADI-2 DAC (if I am correct). But maybe there is benefit in having further adjustment on the subs? This is a key question for me, because to get the DSP + EQ on the sub, I might have to give up on a balanced XLR connection for the sub.

The closest subwoofer options I can see so far in my price range are something like Dynaudio S9, or Rythmik L12 / F12 with the XLR amp. The former has no PEQ on the sub, but the latter does. They have some different options on HPF and the phase (dynaudio has more HPF options). Otherwise if I run subs on RCA I was leaning towards SVS.

The AE1s have both RCA unbalanced and XLR balanced inputs, so they could be run off either of the DAC outputs. I could run them on the RCA and subs on the XLR, but don't have a HPF in that case (although the AE1 do have a +/- 3db treble and bass switch on them but I don't think this is the same thing).

So in summary, what to prioritise in the sub given the features and options of the ADI 2 DAC?

Hopefully this makes sense and someone can help!

2 Reply by KaiS (edited by KaiS 2023-10-22 09:29:52)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Balanced / XLR interconnection ALL THROUGH is a good measure to avoid ground loop related hum and noise.
But - this type of problem only occurs with grounded, 3-prong mains connectors, which your main speakers don’t have.

If you keep an eye on two-prong mains connection on the subwoofers too, you can extend the selection of subs by the ones that have RCA interconnects only.


Looking at your main speaker’s measurements in the Stereoplay review shows, they already have an steep electronic HPF at ca. 60 Hz built in.
But - they still would benefit from some moderate extra HPF above, to reduce their small woofers’ load.
So the sub should offer satellite HPF.


DSP with automatic calibration by a measurement mic is nice to have on a sub, but unless specially prepared for that configuration it likely will fail on a dual-sub setup.
You don’t want to end up with different amplitude/phase responses left and right.

REW might be more suited to handle this situation.


Personally, without having heard this specific model, the Dynaudio S9 seems very interesting.
Dynaudio is a well reputed, long established professional speaker and chassis manufacturer with a focus on good transient response - something you like to see in a sub.

KaiS's Website

3 Reply by rynogee (edited by rynogee 2023-11-26 07:33:01)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Thanks for your advice, I'm leaning to 9s with everything XLR

Is there any chance you could share the measurement chart + information for the AE1s from stereoplay? I can't find it, maybe due to language, or is it behind a paywall?

4 Reply by KaiS (edited by KaiS 2023-11-26 13:55:47)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

rynogee wrote:

Is there any chance you could share the measurement chart + information for the AE1s from stereoplay? I can't find it, maybe due to language, or is it behind a paywall?

The link is further down of the proud manufacturer’s site:
https://acoustic-energy.de/produkt/ae1- … tsprecher/

https://acoustic-energy.de/wp-content/u … 5-2017.pdf

Beware, Stereoplay is an audiophile magazine- it’s information has to be taken with more than a grain of salt.


Get the fun doing a measurement of your own speakers from a distance of ca. 50 cm (to exclude room reflections), on an axis in the middle between woofer’s and tweeter’s centers.
Then you see what’s really going on.

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5 Reply by KaiS (edited by KaiS 2023-11-26 14:39:44)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

AudioTools measurement setup:
https://apps.apple.com/de/app/fft/id298840058

Play AudioTool FFT’s pink noise from the already connected iPad.
- Tap the sine wave icon and set: “Pink”, “On”.
- Once you press the measurement start button (triangle), iPad generates pink noise (and starts to measure, but this can be ignored).


On an iPhone, in AudioTools FFT app, set:

FFT Setting (wrench icon):
• General FFT Setting:
- Equal Points / Octave
- Full Range FFT (= default)
- Flat Plot (= default)
• Advanced FFT Settings:
- Blackman
- Overlap 90%
• Other Settings:
- Thick Plot

In the main plot window:
• Graph Smoothing (down left icon):
- 1/3 Octave
• Graph Decay (down right icon):
- 8s Decay (for continuous reading), or
- Average (for a static average from some time of measurement).


If you like you can change the appearance to dark plot-line on white background (which I do prefer).

This is done in the Global Settings page:
– named “High Contrast Mode”
When there, check the Audio/Global Audio Settings:
– Mic Compensation: Enabled
– Measurement Mode: On

KaiS's Website

6 Reply by rynogee (edited by rynogee 2023-12-17 07:02:42)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Thanks for the tips above. I got the 9s pair now, and have been trying to start integrating. Unfortunately I can't use the suggested app, as no iOS devices.

Do you have a suggestion about the starting point for the HPF and LPF on the sub? I find a huge amount of inconsistent advice on this all over the internet. I have been trying HPF at 80 and LPF at 50, 80 and 100. The LPF is constantly variable, but the HPF is only 0, 60, or 80.

I have the android app Audiotool which is perhaps similar to the suggested iOS one (i also downloaded REW and got a umik 1 mic, but have not had time to learn anything about it or use it yet). I did try using this android app just to get the gain set approximately correctly on the sub vs AE1, but this was only a very quick effort, so I think the gain matching also needs work.

(Dynaudio says the crossover slope is 2nd order Butterworth (12 dB per octave), but I don't know enough yet to use this information)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

KaiS wrote:

Balanced / XLR interconnection ALL THROUGH is a good measure to avoid ground loop related hum and noise.
But - this type of problem only occurs with grounded, 3-prong mains connectors, which your main speakers don’t have.

Well, I am not sure about that. Even 2-prong mains has one wire grounded. The third one - "ground" - is added for increasing the security, that ground is ground. But in fact, it is interconnected with one of two other wires.

At least in european installations. It might be different in US and so....

8 Reply by KaiS (edited by KaiS 2023-12-17 18:52:31)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

There’s no straight numerical solution.
Without measurement subwoofer integration stays guesswork.
So, I suggest to step into REW or Android Audiotool.

This screenshot looks like Android Audiotool could be sufficient for the job, if the cellphone’s microphone or UMIK1 got correct calibration in the lows:

https://play-lh.googleusercontent.com/n0F3G1pPLmwLYtjZbOkeHXUqSwCho_eutFFuk9IJcB6rJf_K2F1mrIxC9aWu1H45P_o=w1052-h592


This measurement shows, the mains have their own, built in, low cut filter at 60 Hz, so this would be the lowest crossover frequency that makes sense for the sub:
https://acoustic-energy.de/wp-content/u … 5-2017.pdf

As a very basic starting point, try:
Mains: no filter or 60 Hz
Sub: 60-70 Hz.
Then check with the sub’s phase setting which switch position gives a more consistent bass responses.

Tuning the x-over frequencies can even address room modes, again measurements are the best aid for good result.

KaiS's Website

9 Reply by KaiS (edited by KaiS 2023-12-17 18:04:30)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Kubrak wrote:
KaiS wrote:

Balanced / XLR interconnection ALL THROUGH is a good measure to avoid ground loop related hum and noise.
But - this type of problem only occurs with grounded, 3-prong mains connectors, which your main speakers don’t have.

Well, I am not sure about that. Even 2-prong mains has one wire grounded. The third one - "ground" - is added for increasing the security, that ground is ground. But in fact, it is interconnected with one of two other wires.

At least in european installations. It might be different in US and so....

The 2nd wire in a 2-prong connection usually (see below) is Neutral, not Ground.
This is an important functional difference.
It might or might not have the same electrical potential as, but can under no means replace Safety Ground.


Most mains systems consist from 3 wires:
• Phase
• Neutral
• Safety Ground.

Sometime you find balanced mains:
• Phase
• Phase inverted
• Safety ground

Phase, Neutral or Phase inverted are NEVER connected in a way that the user can touch their potential.

Only with 3-prong connectors Safety Ground is connected to metallic / conductive parts of the powered device.


In house installations Safety Ground is usually centrally interconnected to the Neutral conductor coming from the power plant AND typically to a water pipe or separate earth fixture for earth potential.

This does mean Neutral or Safety Ground may not be mixed in any way further on.


Only educated experts are allowed to mess with mains power installations.
Laymen: keep your hand off!


EDIT: the correct english term for Zero is “Neutral”, changed that accordingly.

KaiS's Website

10 Reply by Kubrak (edited by Kubrak 2023-12-17 13:17:45)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

OK in Czech Republic, Zerro and Safety ground are the "same". They have the same potential. Or should have.... And in past there were only two wires in the walls and the split to three has been done in electricity outlet.

IMHO purpose of the separate Ground wire is to bring even more safety. Ground goes by two wires Ground and Zerro and if one is loose, there is still the other one....

But OK, I may be wrong. Things may have changed in past years. And also the systems vary country to country, more or less....

I have experienced that "ground" had more than 100 V in our University lab. It was dangerous to touch it.... Of course it was not right.... Just pointing that electicity instalations may ne way wrong in cases....

I just have measured that, and resistance between Zerro and Ground in my building is 1 Ohm. It is clearly well interconnected somewhere....

But, if I think about it, you may be right that under certain conditions ground loops may behave differently if using 2 or 3 wire connection to outlet.

11 Reply by KaiS (edited by KaiS 2023-12-17 13:54:59)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Kubrak wrote:

OK in Czech Republic, Zerro and Safety ground are the "same". They have the same potential. Or should have.... And in past there were only two wires in the walls and the split to three has been done in electricity outlet.

IMHO purpose of the separate Ground wire is to bring even more safety. Ground goes by two wires Ground and Zerro and if one is loose, there is still the other one....

But OK, I may be wrong.

No, you’re right, this configuration is extremely dangerous and therefore long time abandoned at least in Germany.


(BTW: the correct english term for Zero is “Neutral”, my bad)

If, in the above configuration, Neutral comes loose a letal full mains voltage is present at the case of a device, once you switch it on!

Imagine a metal electric tool, holding it strong in your hands.
As soon as you press the start button you become fully 230 V electrocuted.
Due to the muscle spasm caused by the electric current you can’t even let loose.
The only thing people around you can do is pull the mains plug - if they touch you they get an electric shock too!


Neutral and Safety Earth wires might carry (almost) the same potential, but have a completely different purpose, and one cannot replace the other.


In current household installations additionally a “Fault Current Circuit Breaker” - “Fehlerstromschalter”, “Fi-switch” in German, is mandatory.
It compares both Phase’s and Neutral’s current and switches of mains when it detects a differences of 30 mA, assuming it has passed through a person.
These require separate Safety Ground wires to work.

The first thing I installed in my recording studio decades ago where numerous of those Fi’s.
They preserve perfect electrical safety no matter with whatever stinky (and mostly good sounding smile ) amps people appear with at my place for recording.

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Two wires wall installation is dangerous for reason if Zerro/Neutral gets loose, metal elements would not be grounded. And if Hot wire would get loose and touched metal element, circuit breaker would not do anything and folks might be injured.

Because of that the third wire has been added. It may be that modern circuit breaker also checks something concerning Ground and Neutral. We also have that mA check on Ground wire. We have 20 mA.

But it does not mean that somewhere further Ground and  Neutral are not connected.

Anyway, I have got electricity shot several times. If one does not hold it and is sort of isolated and most importantly, it does not go across the heart - one hand on hot other on Ground - it will not do harm to healthy person.

When we were in University Labs we were allowed/instructed to have one hand in a pocket when dealing with electricity appliances.

I have even seen professional guy, who has tested if the wire is hot or not by carefully touching it. He was lazy to use tester, or did not trust the tester....

But I do not instruct anyone to try it in person. ;-)

13 Reply by KaiS (edited by KaiS 2023-12-17 19:06:54)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Kubrak wrote:

Anyway, I have got electricity shot several times. If one does not hold it and is sort of isolated and most importantly, it does not go across the heart - one hand on hot other on Ground - it will not do harm to healthy person.

When we were in University Labs we were allowed/instructed to have one hand in a pocket when dealing with electricity appliances.

I have even seen professional guy, who has tested if the wire is hot or not by carefully touching it. He was lazy to use tester, or did not trust the tester....

But I do not instruct anyone to try it in person. ;-)

I‘ve always followed the rule of “one hand in the pocket” when unavoidably measured on hot circuits - it saved my life at least once when 20,000 V from a cathode ray tube jumped over through the air into my hand.
That was no fun, and luckily it was DC.

Once you experience 230 V mains with slightly sweaty hands (accidentally, not on purpose) you will never do the finger test to detect live wires again.

In both cases I had to stop working for that day, fortunately recovered within some hours.


Not much can go wrong with well designed PSU’s like the ones from RME.
2-prong (ADI-2 DAC and ADI-2 Pro) or 3-prong with soft ground through 1kOhm (ADI-2/4 Pro SE) give good isolation from mains.


Still, old household mains installations should be checked by a professional electrician. I’ve seen weird stuff in old houses here in Germany too.
A simple resistance measurement doesn’t tell the whole story.

It’s even a matter of possible cases of bad installations causing a fire.


BTW: Neutral-to-Safety-Ground bridges inside the outlets deactivate the Fi-Switches’ function. You need 3-wire installations for those to become effective.

KaiS's Website

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

"Neutral-to-Safety-Ground bridges inside the outlets deactivate the Fi-Switches’ function. You need 3-wire installations for those to become effective."

Sure. I do not think those bridges are in new electricity installations.... It used to be in old two-wire ones. But still one may find those in older building. And even in new installations... one never knows.

As I wrote earlier, we used to have around 100V on Ground wire in University Lab.... ;-( I always try to plug everything into one outlet. Mainly in places I do not know. Grounds should be the same in two outlets side by side.... But one never, never knows....

15 Reply by rynogee (edited by rynogee 2023-12-19 11:36:26)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

KaiS wrote:

There’s no straight numerical solution.
Without measurement subwoofer integration stays guesswork.
So, I suggest to step into REW or Android Audiotool.

This screenshot looks like Android Audiotool could be sufficient for the job, if the cellphone’s microphone or UMIK1 got correct calibration in the lows:

https://play-lh.googleusercontent.com/n0F3G1pPLmwLYtjZbOkeHXUqSwCho_eutFFuk9IJcB6rJf_K2F1mrIxC9aWu1H45P_o=w1052-h592


This measurement shows, the mains have their own, built in, low cut filter at 60 Hz, so this would be the lowest crossover frequency that makes sense for the sub:
https://acoustic-energy.de/wp-content/u … 5-2017.pdf

As a very basic starting point, try:
Mains: no filter or 60 Hz
Sub: 60-70 Hz.
Then check with the sub’s phase setting which switch position gives a more consistent bass responses.

Tuning the x-over frequencies can even address room modes, again measurements are the best aid for good result.

Thanks - but what do you think 'consistent' means in this context? I adjusted settings per your suggestion and think it's improved, but the phase switch I'm unsure. it was on 0, but set at 180 it feels like there is marginally 'more' bass, whether it's better or more consistent, hard to say. The monitor is current stacked directly on top of the sub and flush at the front.

16 Reply by KaiS (edited by KaiS 2023-12-19 12:58:19)

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Re: Benefit of XLR and DSP+EQ on subwoofer pair, with ADI-2 DAC

Consistent mean, e.g. bass lines in the music have an about equal loudness and bass fundament through the notes up and down.
Another expression characterizing a linear frequency response.

Phase switch: more bass usually means better phase alignment.
Don’t forget to switch both sides similar, not one side at 0 and the other at 180.

Phase alignment is crucial for a good crossover setting.
Both the mains’ low cut and the subs’ high cut filter frequencies influence the phase in opposite directions.
The mains already have a hardwired cut built in, so I’d start with them unfiltered.
But there’s no golden rule, the result is all that counts.

Using AudioTool would really help to perfect the setup.
Start with a measurement at ca. 0.5m distance from the speaker’s fronts.

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