Faulty internal crossover?

[mossman77]

It's always good to double check everything or look at things from different angles.....

Yeah, and know your left from your right

 

[PENG]

Let me preface with, if I were seeing the behavior as I described, the receiver would certainly be the cause, but....

Apparently I confused the L and R output in REW with the L and R output on the receiver and which speaker was playing for a given sweep (I was seated well to the side of the LP and didn't verify which speaker was actually playing). So...my apologies. I was mistaken. I'm a dummy. A smart dummy though because I would have been right if I knew my right from my left. Lol.

...it's the room (face palm).

So, now that has been solved, evidently Audyssey can't correct it, so I guess I just accept it and appreciate the free additional bass response I am getting from the right speaker. Lol.

Good to know you got it, finally. I don't know how long you have been using REW, I have been using it for many years and would still make such mistakes once in a while though as soon as I noticed something weird I knew where to do and fixed it quickly. Believe it or not, I was going to mention the REW left/right output as a possible scenario but forgot, it was around midnight at the time.

Pogre is an experienced user, that's why he kept thinking room mode etc.. Those U shape after XO point are not unusual at all, even if Audyssey is on, it can only improve things to a point, room modes are hard to overcome no matter what auto Room EQ you used. I have tried Dirac Live, Audyssey, with and without minidsp/REW and settled on the free (not really but..) Audyssey (XT32 Sub EQ HT) as it can do a very good job in the range from 15-250 Hz, but for people who must see a best possible looking curve (like mine and Pogre's just for example), the Editor App+REW is a must, with or without any help from minidsp. The SR5000 series are limited to the primitive XT version, but the minidsp solution could be quite effective depending on how it is used.

 

[PENG]

I wonder if you guys remember not long ago another poster reported trouble with XO not rolling off too. Some (I think one might have been me of us tried telling him he may be hearing from his subwoofer but he wouldn't confirm if the sub was in fact turned off. He thought because he put his ears against the speaker, he was hearing the LF below XO only from that speaker.

Mossman77's case (a different scenario but basically same principle would apply) just reinforced the fact that low frequencies, such as below 80 Hz are in fact very non directional, so if a REW (or similar software) user wants to be sure only one speaker is playing the note, it is good practice to make sure the other speakers are physically off.

There aren't too many golden ears who can tell every minor details/differences right?

 

[Pogre]

I might hold the record for dumbest move among us regulars. Wait til you fry a $1700, 7 channel amp with stupidity.

Yup. "I should play with bi amping!". I should have practiced "removing the straps" before powering everything up. Talk about a facepalm...

 

[PENG]

Thanks man. I appreciate that.

Thank you for sharing your findings, hopefully that will help someone else who, if and when faced with simpler puzzles may google for help and find this.

 

[mossman77]

That will really nail it down. You will also be able to find where this is occurring by measuring the preots and the speaker outputs. I assume you also have a signal generator as well, as that will also be required.

Good to know you got it, finally. I don't know how long you have been using REW, I have been using it for many years and would still make such mistakes once in a while though as soon as I noticed something weird I knew where to do and fixed it quickly. Believe it or not, I was going to mention the REW left/right output as a possible scenario but forgot, it was around midnight at the time.

Pogre is an experienced user, that's why he kept thinking room mode etc.. Those U shape after XO point are not unusual at all, even if Audyssey is on, it can only improve things to a point, room modes are hard to overcome no matter what auto Room EQ you used. I have tried Dirac Live, Audyssey, with and without minidsp/REW and settled on the free (not really but..) Audyssey (XT32 Sub EQ HT) as it can do a very
good job in the range from 15-250 Hz, but for people who must see a best possible looking curve (like mine and Pogre's just for example), the Editor App+REW is a must, with or without any help from minidsp. The SR5000 series are limited to the primitive XT version, but the minidsp solution could be quite effective depending on how it is used.

I posted my overall system response (low end only) in another thread. Here it is again. Integration with subs and low end response looks pretty good, right? No smoothing applied. My only challenge now is to get the lower end decay times down.

 

[PENG]

I posted my overall system response (low end only) in another thread. Here it is again. Integration with subs and low end response looks pretty good, right? No smoothing applied. My only challenge now is to get the lower end decay times down.

View attachment 35451

Is that for left + right + sub(s)?

 

[mossman77]

Is that for left + right + sub(s)?

Yes. With Audyssey and miniDSP HD.

 

[Pogre]

Yes. With Audyssey and miniDSP HD.

Did you build that house curve with the Mini or have you tried playing with DEQ and the RLOs? I go for a very flat, even response 1 port open, EQ1. When I have that I pull the port plug, switch to EQ2, turn DEQ on and bump my sub levels a couple of dB. That gives me a nice house curve without having to manually build one with the Mini.

*Edit: Your curve isn't bad, but my thinking is you might be able to improve that decay time with less manual adjusting.

 

[mossman77]

Did you build that house curve with the Mini or have you tried playing with DEQ and the RLOs? I go for a very flat, even response 1 port open, EQ1. When I have that I pull the port plug, switch to EQ2, turn DEQ on and bump my sub levels a couple of dB. That gives me a nice house curve without having to manually build one with the Mini.

I level matched the subs, ran Audyssey with 1 port/EQ1, then built/applied a house curve and opened up the other port/switched to EQ2. I didn't have to mess with my sub levels.

 

[Pogre]

I level matched the subs, ran Audyssey with 1 port/EQ1, then built/applied a house curve and opened up the other port/switched to EQ2. I didn't have to mess with my sub levels.

That's not a "wrong" approach at all, but my thinking is you could possibly improve that decay with less manual adjusting. Just a thought, if you wanted to try a different approach.

 

[mossman77]

That's not a "wrong" approach at all, but my thinking is you could possibly improve that decay with less manual adjusting. Just a thought, if you wanted to try a different approach.

I really didn't do much manual tweaking. Audyssey had things looking pretty good. The miniDSP is just flattening a few areas. I set the individual boost to 3dB and total to 9dB I believe.

Isn't decay time more of a room effect? I was under the impression that room treatment was the only way to get decay times down, or at least the most effective way.

 

[PENG]

Pogre may be referring to the inherent phase shifts, introduced by the IIR filters such as REW's, assuming you are using the minidsp HD with REW generated filters. As for the cumulative spectral decay, what are your room dimensions, is it well damped by rugs, furniture etc.? It looks fine above 20 Hz

It may be easier to look at the waterfall if you set the Y-axis minimum to your noise fall level. I think it is not bad at all above 20 Hz. If you change the Y-axis minimum to your noise floor level it would be easier to look at.

 

[mossman77]

Pogre may be referring to the inherent phase shifts, introduced by the IIR filters such as REW's, assuming you are using the minidsp HD with REW generated filters. As for the cumulative spectral decay, what are your room dimensions, is it well damped by rugs, furniture etc.? It looks fine above 20 Hz

It may be easier to look at the waterfall if you set the Y-axis minimum to your noise fall level. I think it is not bad at all above 20 Hz. If you change the Y-axis minimum to your noise floor level it would be easier to look at.

The room is very large relatively speaking, with all sorts of angles and obstructions. Rough calculation of nearly 6,000 cubic feet.

Ah yes, my noise floor is in the 40's. I'll have to increase the system gain and quiet the room down a bit (turn off air, appliances, fish tanks) and re-measure.

 

[Pogre]

Pogre may be referring to the inherent phase shifts, introduced by the IIR filters such as REW's, assuming you are using the minidsp HD with REW generated filters. As for the cumulative spectral decay, what are your room dimensions, is it well damped by rugs, furniture etc.? It looks fine above 20 Hz

It may be easier to look at the waterfall if you set the Y-axis minimum to your noise fall level. I think it is not bad at all above 20 Hz. If you change the Y-axis minimum to your noise floor level it would be easier to look at.

Peng, I didn't even think about where the Y-axis was set.

Yes, agreed. Now that I look at it again that's not a bad waterfall at all. I didn't think it was terrible to start with, but even better now!

 

[PENG]

The room is very large relatively speaking, with all sorts of angles and obstructions. Rough calculation of nearly 6,000 cubic feet.

Ah yes, my noise floor is in the 40's. I'll have to increase the system gain and quiet the room down a bit (turn off air, appliances, fish tanks) and re-measure.

If you are going to re-measure, it wouldn't hurt to try leveling the range between 18 and 80 Hz. Turning off the HVAC system is a good idea, probably not much you can do about the fridge if you have one nearby.

After obtaining a flat FR curve, then you can tip it up towards 18 Hz again but at lease you know you have a flat baseline to look at and analyze at leisure. As it is now from 80 Hz you are in the low 60s. With a noise floor in the 30-40 dB, I would like my plots to be in the 70-75 dB average.

 

[mossman77]

Scale adjusted...

 

[mossman77]

If you are going to re-measure, it wouldn't hurt to try leveling the range between 18 and 80 Hz. Turning off the HVAC system is a good idea, probably not much you can do about the fridge if you have one nearby.

After obtaining a flat FR curve, then you can tip it up towards 18 Hz again but at lease you know you have a flat baseline to look at and analyze at leisure. As it is now from 80 Hz you are in the low 60s. With a noise floor in the 30-40 dB, I would like my plots to be in the 70-75 dB average.

I see what you are saying. I applied a house curve to tilt the response towards the low end. Couldn't I just increase the gain on the front channels to level things out a little? Audyssey set the front channels to -7.5. Things are sounding pretty level and well integrated to me though. I do find myself cutting the sub level by 4 or 5dB depending on source content though.

 

[PENG]

I see what you are saying. I applied a house curve to tilt the response towards the low end. Couldn't I just increase the gain on the front channels to level things out a little? Audyssey set the front channels to -7.5. Things are sounding pretty level and well integrated to me though. I do find myself cutting the sub level by 4 or 5dB depending on source content though.

Yes you can do that too, but regardless of your approach, to make things pretty I bet you are going to have to spend hours and hours and will likely end up with sore back muscle pains etc etc. So if it sounds good and level to you now, that's what matters anyway so may as well leave it alone, relax and enjoy.

Below was one of my base line flat curve, no smoothing, from there I made a lot of tweaking, including making the 15-60 Hz to slop up a few dB.

 

[mossman77]

Yes you can do that too, but regardless of your approach, to make things pretty I bet you are going to have to spend hours and hours and will likely end up with sore back muscle pains etc etc. So if it sounds good and level to you now, that's what matters anyway so may as well leave it alone, relax and enjoy.

Can't do that quite yet. I've only been using one measurement point while getting the hang of REW and the miniDSP. Now I need to take several more points and get a good response across the MLP. Sounds great when I sit in the middle of the couch (where the mic was placed), but I am getting some localization of the sub when I shift to the left (closer to the sub located on the front wall to the lower left of the mains). Sitting to the right sounds pretty good.

I'm guessing after taking several measurements I keep the best of the set, average all of them, then apply my filters?

FYI, I've been taking three points for Audyssey while experimenting, but will be taking 6 next go around (can't take measurements behind the MLP because it is up against the wall).

Regarding the room mode produced by the right main speaker, should I perhaps experiment removing one of the passive radiators (and blocking off the opening obviously) to attempt to tame the low end a bit? I have the DT Mythos Nine speakers, which have dual 4.5" drivers and dual 4x8 passive radiators (per speaker).