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Hi Guys,

I have a DDRC-24 and since I like a volume display my Streamer feeds DDRC24 and DDRC24 Ch1 (Left) and Ch2 (Right) go to an integrated amp that controls volume. The amp’s stereo high level speaker out goes to both speakers and sub.

To create a pseudo crossover between sub and bookshelf speakers, I increased the gain on the sub before running Dirac. The Orange trace is just my mains before dirac, the Red trace again without dirac but with Sub turned on and with a high gain.

It seems to work as the blue trace shows the result after Dirac.

But look at the Pink and Orange which is just my mains, with and without Dirac. Between 100-200Hz, Dirac has reduced the overall level but hardly touched the mains but how? How can it decrease the sub but not the mains since they’re on the same feed? Has it reversed the phase? Even so this would again reverse it for both sub and speakers!



Confused.

Not exactly sure but I imagine that your mains and sub impacted by the room differently. How are they located in the room?

Also having a bit of trouble wrapping my head around your setup from a crossover (or lack thereof) perspective. I assume that the sub has a LPF? And I assume that there is no HPF on the mains? Have you done any near field measurements of the mains or subs individually to get an idea of how they are behaving without room interaction?

Michael

I'm guessing those measurements are for left and right speakers played together? I think that's the cause of the confusion as there may be phases changes between the two sides.

If you try the same comparison but only using say the left channel for all three measurements then I think you'll find it makes more sense

mdsimon2,
So the sub accepts line level and/or high level inputs. My speakers are wired conventionally but then you take the positive from both along with one negative and send this to the sub.

There is no crossover set in the ddrc because i would then need to send line outs from the ddrc24 to the amp and sub and use the ddrc for volume control when it has no display.

So full range left and right goes straight to amp.

Mdsimon2, Ultrasonic,
I think it’s sensible suggestion to take more measurements of left and right individually and see what it looks like.

It’s obviously not a problem as when Dirac is on the curve is pretty flat (btw I used psychoacoustic REW graph smoothing) but I’d just like to understand!

There is no crossover set in the ddrc because i would then need to send line outs from the ddrc24 to the amp and sub and use the ddrc for volume control when it has no display.

I understand that you do not have a crossover set in the DDRC but presumably your active sub has a built-in LPF crossover (whether fixed or adjustable)? I imagine your mains do not have a HPF crossover but do you have any idea what the low frequency roll off looks like? Are they sealed or ported? How are the mains located in relation to the sub? Just trying to get a feel for the transition between the mains and subs prior to considering room effects.

Michael

asx77 wrote:

It’s obviously not a problem as when Dirac is on the curve is pretty flat (btw I used psychoacoustic REW graph smoothing) but I’d just like to understand!

Not necessarily. Having a flat response for both together is good for when notes are panned in the center of the soundstage. What happens looking at the left and right channels on their own is relevant for sounds that are not.

mdsimon2,
Ah sorry misunderstood the question. The mains (together and at the listening position) without Dirac are the orange trace. I suppose because of the room their output dips below 150hz but rises again has they go down to 40hz. The orange trace was taken with the sub off. They are ported at the rear.

The sub has its filter set at 99hz ( the highest I can set it) but think it starts rolling off around 120hz.

I have a sofa at one end of the room against the wall and the speakers and sub are opposite end. There is a bay window. The speakers sit either side and in front of the bay so they have a little room behind them. The sub sits between them in the bay.

Ultrasonic - you see that’s why I like this forum... I’d not even considered that. I want to squeeze every last ounce of improvement out of my set up as poss!!