A disastrous subwoofer journey

[liverpool_for_life]

Next I tried as per Liverpool4life suggested and added delay to the front sub.

Good on you for being open-minded enough to try something that seems counter-intuitive at first glance. It's all about how bass from your two sources combine at your listening position.

6th-Has two graphs where both are after EQ applied using mini dsp. Top response is the result of adding delay to front sub

I'd take that response, TBH. Even if I believe that MSO will get you better. How does it sound to you?

 

[Love4sound]

I'd take that response, TBH. Even if I believe that MSO will get you better. How does it sound to you?

I just completed audysey. One weird observation is that it set sub gain to -1.5. I find this very odd given that I have kept both the sub at 12’O clock. For my small room both subs at 12 position should be very loud.

 

[liverpool_for_life]

Correct, but by not correcting them individually first they are just going to cut each other off

That's not true. No EQ doesn't necessarily imply that the combined response is going to have nulls. You really need to examine the individual responses and how they combine at your MLP.

I can see the argument for individual EQ so that the combined response is better (what MSO does, although Mark Seaton advises against this), but there's no useful reason for individual EQ for the 2 subs without taking the combined response into consideration.

 

[MaSh]

That's not true. No EQ doesn't necessarily imply that the combined response is going to have nulls. You really need to examine the individual responses and how they combine at your MLP.

I can see the argument for individual EQ so that the combined response is better (what MSO does, although Mark Seaton advises against this), but there's no useful reason for individual EQ for the 2 subs without taking the combined response into consideration.

Hmm ok. So what are you suggesting the OP should do? Measure them them together?

MaSh

 

[Love4sound]

So last night I played few tracks using the graph shared in my previous post and it was much better but not perfect and I still preferred a single sub performance overall but I didn’t test much either. Main reason as some of you know I have ear problems. After 6 months of not using HT and when I got a single rythmik I did enjoy a lot watching one movie a week using HT and occasional music listening. Tinnitus didn’t spike and things where fine. Now after back to back tests last night my ears again started ringing very loud and I got so scared but thank god today morning after a good sleep it’s in control again. Wake up cal for me and I have taken a strong decision prioritising health more then best bass. Now I have decided two things. First is give MSO a shot. Since I already had the graph all I had to do was load it to MSO and get the predicted curve and delay,PEQ filters to be loaded in mini dsp. I will take complete rest for a week and load them to test and update by next week.Second is I have a doubt with my chain and another fm who has same avr, mini dsp set up will help me by comparing side by side to eliminate any issues with the gear. After completing both these steps I will sell one sub if not satisfied and stick with one.

 

[liverpool_for_life]

So what are you suggesting the OP should do?

Not just OP, but for anyone integrating 2 (or more subs). What you're looking to do is to get them to combine constructively and eliminate cancellations in their effective working range.

This means overlaying the individual responses with the combined response to ensure that there aren't regions where the 2 subs are effectively fighting each other. If they are, the remedy is to move the subs to better positions. If that isn't possible (or enough), the next step is in the time domain. Typically, this involves delay manipulation on either sub. In addition to combining constructively, you're more importantly looking to avoid nulls in the combined response, with flattening of peaks achieved next by EQ.

Measure them them together?

As part of the steps described above, yes. Because what you hear is the result of how all your bass sources combine in your room at your LP.

 

[MaSh]

Not just OP, but for anyone integrating 2 (or more subs). What you're looking to do is to get them to combine constructively and eliminate cancellations in their effective working range.

This means overlaying the individual responses with the combined response to ensure that there aren't regions where the 2 subs are effectively fighting each other. If they are, the remedy is to move the subs to better positions. If that isn't possible (or enough), the next step is in the time domain. Typically, this involves delay manipulation on either sub. In addition to combining constructively, you're more importantly looking to avoid nulls in the combined response, with flattening of peaks achieved next by EQ.



As part of the steps described above, yes. Because what you hear is the result of how all your bass sources combine in your room at your LP.

Cool. Hope this works for OP.

MaSh

 

[SrikanthYadav]

So last night I played few tracks using the graph shared in my previous post and it was much better but not perfect and I still preferred a single sub performance overall but I didn’t test much either. Main reason as some of you know I have ear problems. After 6 months of not using HT and when I got a single rythmik I did enjoy a lot watching one movie a week using HT and occasional music listening. Tinnitus didn’t spike and things where fine. Now after back to back tests last night my ears again started ringing very loud and I got so scared but thank god today morning after a good sleep it’s in control again. Wake up cal for me and I have taken a strong decision prioritising health more then best bass. Now I have decided two things. First is give MSO a shot. Since I already had the graph all I had to do was load it to MSO and get the predicted curve and delay,PEQ filters to be loaded in mini dsp. I will take complete rest for a week and load them to test and update by next week.Second is I have a doubt with my chain and another fm who has same avr, mini dsp set up will help me by comparing side by side to eliminate any issues with the gear. After completing both these steps I will sell one sub if not satisfied and stick with one.

ya, should try all fm's advices, its not wrong in taking suggestions bro , But decide what works for you finally.

 

[Love4sound]

I tried MSO today and it failed miserably. Attaching the results of MSO. With MSO delays, gain and PEQ loaded to the mini dsp I do get the best flat graph. But after running audysey the graph looks very weird and drops on both sides of 50hz. Now I tried the conventional method that is get the best combined graph by adding delays in mini dsp. Adding 4 delay to the front sub gave the best results and I used it for EQ. Still not convinced as while I was integrating it with mains and center I get a dip at 90hz. Played few scene and again I don’t feel the dual subs playing well together.

1st Image-Has two graphs. Purple is post audyssey of sub response and green is post eq using MSO.

2nd Image-Usual method. Best response i eqed. Purple is post eq applying 4 delay to front sub using mini dsp and red is post audyssey. Audysey gives good boost on the low end but a 5db drop post 100. Not sure why audysey is reducing 5db post 100hz.

3rd Image- Graph of single vs dual.Black is dual and orange is single. I mean what the hell literally no improvements and response is the same. In fact the tightness and punch I get with the single is gone in duals.

Another issue I noticed is Audysey sets sub gain to -1.0 or 2 every time. Both subs are gain matched with the knob at 12’O clock.when I used spl meter from rew it reads at 90-92 dB which is very loud and to be expected as I have the gain knob in sub set at 12’O clock. So after eq using mini dsp if I check the spl meter it drops to 65-70db from 90db. Is this normal and is this the reason for the avr to set gain to very high value? How can I over come this?

I really need your help. With my ear problems I cannot experiment much.

 

[jenson]

Complete novice in this space...chiming in combinations...

1. Have you tried swapping sub's
2. Can you place sub's diagonally opposite to how it is placed now (not sure if you shared your room details... Aren't sub's sensitive when placed near an opening)
3. Assuming you have tried placing it in classic stereo format
4. Finally, do you have a freind who can manually move sub's when working... Would be best to tune it that way...

 

[Love4sound]

Complete novice in this space...chiming in combinations...

1. Have you tried swapping sub's
2. Can you place sub's diagonally opposite to how it is placed now (not sure if you shared your room details... Aren't sub's sensitive when placed near an opening)
3. Assuming you have tried placing it in classic stereo format
4. Finally, do you have a freind who can manually move sub's when working... Would be best to tune it that way...

Yeah tried swapping and they both measure the same. They are currently placed diagonally opposite. Front right and rear left

 

[Decadent_Spectre]

This is the last time I will say it, time domain, your issue is not frequency. Just remember that when your aligning in time your not only aligning each sub to each other, but also each sub to each speaker, particularly L/R. Adjust the delay and phase on the second sub.

 

[jenson]

Room layout may help pros here to dissect.

Also, quite possible that the sub near to your listening seat is overpowering. Perhaps some room dampners or diffusers near listening position MAY help..

 

[Love4sound]

This is the last time I will say it, time domain, your issue is not frequency. Just remember that when your aligning in time your not only aligning each sub to each other, but also each sub to each speaker, particularly L/R. Adjust the delay and phase on the second sub.

Yeah definitely an issue with delay and I did experiment different values but sharing the one that turned out to be the best. Also I get a warning message when I run sweep. I am not able to figure this out

Room layout may help pros here to dissect.

Also, quite possible that the sub near to your listening seat is overpowering. Perhaps some room dampners or diffusers near listening position MAY help..

Please find the room lay out. 1&2 are subs.

 

[Decadent_Spectre]

A diffuser/dampener that he could put (practically) near himself is not going to help him. He says its fine with one sub, that means the second sub is messing up the time coherency. He could try to delay and/or phase the first sub but then he'd need to do so to his speakers as well to maintain their time interaction. If he can adjust phase 180 (5 degrees at a time) degrees and adjust time from 0-20ms in 0.1ms increments I'm sure he will find his solution. Ideally he'd be able to do this for the first sub/speakers as well.

Edit : Corrected phase mistake

 

[Love4sound]

A diffuser/dampener that he could put (practically) near himself is not going to help him. He says its fine with one sub, that means the second sub is messing up the time coherency. He could try to delay an/or phase the first sub but then he'd need to do so to his speakers as well to maintain their time interaction. If he can adjust phase 360 degrees and adjust time from 0-20ms in 0.1ms increments I'm sure he will find his solution. Ideally he'd be able to do this for the first sub/speakers as well.

So your suggestion is to add delays to the rear sub. I tried but the best response I got was adding delays to the front sub. So far I have tested single sub performance, delays added to front sub and delays added to rear sub. In terms of measurements and how it sounds adding delays to front sub is better compared to adding delays to rear sub.

 

[Decadent_Spectre]

Note how I mention doing so for the speakers as well. If you adjust delay for the front sub (which I assume is your "single" that you like) then it's interactions with the speakers will change. IOW add the same delay/phase to the speakers as you did to the front sub.

 

[Love4sound]

Note how I mention doing so for the speakers as well. If you adjust delay for the front sub (which I assume is your "single" that you like) then it's interactions with the speakers will change. IOW add the same delay/phase to the speakers as you did to the front sub.

Yeah got it. Reason for me to set delay to the front sub is I get the best response as shown in the image.Orange graph is the best response I got adding delays to front sub and the blue graph is of the best response of adding delays to rear sub. Second image is the individual response of both subs. Red is the pure direct response of front sub and the black is the PD graph of rear sub

 

[Decadent_Spectre]

As I've mentioned what you describe is not a frequency problem, saying you chose one over the other because it measures well according to you is not going to solve your issue. If it sounds better then I agree. In either case your issue will be solved IMO when you are able to adjust the rear sub or front sub and speakers together, in both phase and delay, 180 degrees in 5 degree increments and 0-20 ms delay in 0.1ms increments. By this I mean adjust and listen, no need to measure it.

Edit : Added clarification.

 

[Love4sound]

As I've mentioned what you describe is not a frequency problem, saying you chose one over the other because it measures well according to you is not going to solve your issue. If it sounds better then I agree. In either case your issue will be solved IMO when you are able to adjust the rear sub or front sub and speakers together, in both phase and delay, 180 degrees in 5 degree increments and 0-20 ms delay in 0.1ms increments.

Yeah ultimately to sound better is why I use measurements as a baseline. I am indeed trying my best to integrate all to play together and so far experimented so many delay values. I even tried MSO and not sure why it failed. Any chances that there is a issue with my chain? Two weird things I noticed.

1-After introducing mini dsp I get a loud thud sound on the subs whenever I pause and resume. Some times even when I switch on the main plug and when mini dsp loads it produces the thud sound

2nd-Before I went duals I calibrated a single sub in rear position as well. The rear sub had excellent bass and punch in where the front sub did not have bass. I played various scenes where the punch and bass was missing in the front sub for hours and shut my system and for 3 days I never touched anything or made any changes. So when I watched the same scenes after 3 days the bass was not there and it was flat in the same scenes I tested 3 days back. I know it sounds weird but something is not just right. I know another fm who has his chain similar to mine. Avr 4500, mini dsp and nvidia shield. I have decided to take my avr, mini dsp and shield to his place for him to test using my gears to confirm if he notices any changes in performance. Once confirmed I have decided to sell one sub. I was anyways 70-80% happy with one sub and Atleast able to enjoy watching one movie a week and occasional stereo listening. Ever since I got this second sub all I am doing is trying and failing to integrate it.