How to add digital sub eq, please?

So my system goes: Oladra USB out->ProUSB fibreoptic converter->MSB Reference DAC->Audionet Humboldt

Then the Humboldt powers the main speakers AND gives a pre-out to a pair of active subs.

What I would REALLY like is a second digital out to do some digital EQ and then pass to the subwoofers.

How would I go about getting this?
Can Oladra give a second digital output?

Processing adds a bit of delay so you would have send everything through your chosen processing engine. You would just need to construct a curve that only EQ’s the lower frequencies.

Thanks for your reply.
Yep, the delay would need consideration, kennyb.
I would still like to have a crack and hear what it sound like if I can get a second digital out of the Oladra.
I do have a DSP option for the second DAC, which leaves the main speakers as pure out of the MSB as I can get them.

Don’t know how the Oladra works but with my P2 reclocker I have simultaneous digital outputs.

I think you will be saying goodbye to pure if you opt for using any EQ. Realism takes a hit when phase and timing are harmed.

Thanks, DrPO- which two outputs are active at the same time?

I use AES EBU and SPDIF - but I never use them truly simultaneously…they feed the main DAC (for the speakers system) and a DAC / HeadPhone amp

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You maybe quite right. I’ll know once I get it set up.
“It’s only the bass???”

Many instruments extend into the bass.

I know, kennyb123, I was only joking. As you know, plenty of people use systems with very limited bass extension, so I was joking that people don’t care about bass anyway. I do, and I am interested to try this system.
I am unsure whether a small phase / time difference will matter, after all, plenty of systems use subs in the corners of the room.

If I can find a way to tap off a second digital output, I’ll let you know how it goes.

I recently added the most entry level REL sub to my small desktop system. REL advocates a connection directly from the speaker outputs of the amp to both sub and main speakers. This way you don’t need a sub out … This humble sub has transformed the small system and now I suddenly find myself spending a lot of time in there :slight_smile:


Those systems with subs in every corner take care of the room modes at the listener position. You need to measure the individual subs and set all the delays and eq. Not an easy job.
Another interesting method is the Double Bass Array. Here the bass speakers are placed in an array in or at the frontwall behind the main speakers (and the same set of drivers delayed and out of phase in or at the back wall). That gives a more directional sound and room modes will be canceled out. Also the back wall disappears for low frequency energy. But you need to have a rectangular room for this system to work properly, they say.

An extra 1,8 ms digital delay acts like you put the subs 60cm behind the main speakers. At 100 Hz this causes a phase shift of 65 degrees. That doesn’t seem like a lot, but it could just mean that you will have some cancelation around 100Hz, because there are probably more phase issues between subs and main speakers which will all add up. When you get over 90 degrees, cancelation will start to happen. That doesn’t sound “right”, as Kennyb stated and I have recently experienced the same thing.
But it also depends on your specific situation. If you are suffering from severe roommodes, nothing will help other then getting rid of those modes first. And to do that in an electronic way with dsp, it is best to have the stereo towers (subs and main speakers) all in phase so that the eq can do it’s job.

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.arjan, do you know how to get a second digital out of the Oladra?

You offer words of of wisdom. DSP isn’t a silver bullet.

I struggled for years with bass problems in my room. What helped most was following a tip ASC recommended. I was able to place my speakers 29% out into the room from the front wall and my chair likewise 29% from the back wall. This helped tremendously. Of course not everyone can do this, but I mention it only because I didn’t have to move my speakers much to achieve this result.

I thought someone suggested that some of the reclocker outputs are simultaneously active. I take it that won’t solve your problem.

My guess is that you will need to solve the software problem first. HQPlayer might be your best bet. If it could simultaneously stream to two NAAs, then you could add another Player to give you another digital output.

You could use roon and 2 pi4 over ethernet and then group them in roon.

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If you are using Roon, then all you need to do is have some convolution filters created. Roon then sends the digital signal to the MSB, everything is taken care of before it hits the DAC and there is no no lag between mains and subs. The DAC then sends an analog signal to the Humboldt.

Contact Mitch at Accorate Sound

All you have to do is take the room measurements using REW software, send him the file and he sends you back files until you like the results.

If you want a file that just addresses the bass in the room, he can do that. He can also send you a file that addresses the whole room to see how you like that. In either case, you’ll be able to take the second DAC that you are using for the subs out of your system completely because everything is done in the server, not in a DAC.


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Thanks for all replies.
I’ll try the second digital out first, then consider Accurate Sound to help write some convolutions.
Thanks again