[bernardo]

Looking for feedback from anyone who has tried or uses Danny's past audio show set-ups using sealed servo subs in the rear room corners running out of phase.

I plan to use two open baffle subs I have along with a Dayton SA1000 amplifier, which contains controls similar to the Rythmik A370 amplifier. My main speakers are Super-7s.

I am trying to reduce low bass frequency resonances I have in the front two corners of the room. I have tried broad band bass traps but they do not work - stacked four 17" x 17" GIK Soffit Traps in one corner with no impact on the resonances.

Using the Stereophile Test CD bass tones the most significant ringing I hear from my listening position is from 40 hz thru 100 hz; listening at the rear corner of the room at the floor 40 hz and 50 hz are producing the resonance.

My room is 15' x 24' x10.5' with quite a bit of GIK Soffit, Monster, and 244 Bass Traps in the front half of the room. Speakers set up on the short wall. I have some treatment in the room's rear corners and wall but I don't hear much improvement from them.

Why am I trying open baffle subs instead of sealed servo subs? I can try my open baffle subs purchasing a Dayton SA1000 amp for $515 with a 60 day return option. Two F12 Rythmik Sealed Servo Subs would be $2,520 with no return option.

Anyone have some words of wisdom for me?

[jtcf]

Have you considered SVS subs that have an equalizer built in along with phase,Q control, crossover,volume, etc. that can be controlled from your listening chair with their app?They have a generous return policy. Just another option to think about.

[Early B.]

Prior to adding more subs, let's see if we can optimize your main speakers. Do you have any room pics you can share? Include a pic of your A370 settings. How far are the Super 7's from the front wall?   

[bernardo]

Speaker front baffles are 7'-5" from the front wall. Center of speakers are 3'-6" from the side walls. Listening position is 7'-5" from the back wall.

Not using the Rythmik PEQ due to ineffectiveness and having installed a DSPeaker Anti-Mode 8033S-II between preamp and Rythmik amp to EQ the bass at the listening position. I have tried engaging the Rumble Filter but it makes the bass sound rolled off and anemic.

[Tyson]

What were the settings you had when you were trying to use the Rythmik PEQ?  There are a couple things that are counter-intuitive and might not be optimally set.

Also, do you own/use an iPhone?

[WGH]

Using the Stereophile Test CD bass tones the most significant ringing I hear from my listening position is from 40 hz thru 100 hz

I'm not surprised, both your speakers and your seat are close to the 47 Hz and 75 Hz room nodes.



A friend had the opposite problem, no bass even with a REL S/510. We move his seat forward 2' and there was the bass.

[bernardo]

Tyson-
With the Freq set at 40hz  and 50 hz I have adjusted the PEQ Bandwidth from min to max with the Gain set at -12dB. It did not make any audible difference. I do not have an iPhone.

WGH-
Moving my listening position will not change the bass resonance unless I move the speakers. That said wouldn't moving the speakers towards the front wall increase the bass energy feeding the bass resonance in the corners? Seems like moving the speakers further into the room would be the only way to reduce it.

[bernardo]

FYI I do not hear the 40 hz and 50 hz at my listening position with the 8033 in the loop. It cleaned up the bass on my two reference recordings - Holley Cole Train Song and Telarc Super Bass 2 on which the Rythmik PEQ had no effect. I actually have very good bass performance but know that reducing the resonance in the front corners would improve it.

[Tyson]

First thing, set the PEQ bandwidth to minimum and not to maximum.

Next thing we need to measure each speaker by itself to see if the bass hump is mainly coming from one speaker, or if it is coming from both. 

There are a few ways you can measure, the one I used for bass is to run pink noise through my system and use an FFT measuring app on my iPhone.

If you have a different smart phone, there might also be an FFT measuring app you could download and use it.

I like doing it on my phone because it lets me be mobile when doing the measuring.   I can play pink noise through the system and see what the bass looks like at the seating position.  I can also walk around my room and see how the bass modes change in different areas.

What we need for you is a precise measure of where the bass mode is so we can set the PEQ exactly to that frequency.

[Early B.]

Not using the Rythmik PEQ due to ineffectiveness and having installed a DSPeaker Anti-Mode 8033S-II between preamp and Rythmik amp to EQ the bass at the listening position.

Take Tyson's advice and remove the 8033. 

[mkane]

 

[Danny Richie]

What input are you using on the A370PEQ servo amp on your Super 7's?

[bernardo]

Here are my current settings:

LINE IN Left
PEQ OFF
DELAY/PHASE 0
CROSSOVER 120
SUBWOOFER LINE IN LOW PASS AVR/12
SUBWOOFER RUMBLE FILTER OFF
EXTENSION FILTER FREQ 28
EXTENSION FILTER DAMPING HI

[Danny Richie]

Here are my current settings:

LINE IN Left
PEQ OFF
DELAY/PHASE 0
CROSSOVER 120
SUBWOOFER LINE IN LOW PASS AVR/12
SUBWOOFER RUMBLE FILTER OFF
EXTENSION FILTER FREQ 28
EXTENSION FILTER DAMPING HI

When we had them here in our listening room we had the crossover control set at about 90.
Phase was at about 1:00.
We used low damping and 14 Hz extension.

Is there any way you can take some room response measurements?

[Tyson]

Make sure to remove the DSPeaker Anti-Mode 8033S-II before you measure the speakers.

[bernardo]

Danny-
I do not have any way to measure room response. I have a couple of friends who have limited experience with measuring system response.

My plan was to (1) try the out of phase subwoofer array based on low cost (shipping the Dayton unit back to the manufacturer); and (2) try Vicoustic Vari Bass Resonators which are returnable for a restocking fee to my local dealer, as potential ways to reduce the bass resonance. Both of these are low risk financially.

If these approaches don't work I intend to work with Jeff Hedback who can provide me with room measuring to help identify any solutions.  It may well be that I decide it is not worth the expense to eradicate the bass resonances I have. Most likely a pair of PI Audio AVAA C20 ($3125) Electronic Bass Traps would work but I am not willing to spend $6250 on active devices which will eventually fail. I have two Spatial Audio Black Holes which are mildly effective but both subs have failed and had to be replaced. If they fail again they will be headed to the landfill. Bag End E-Traps may be a more cost effective solution at about half the cost of the AVAA but they are not currently in production - manufacturer says maybe next year.

Passive solutions are GIK T40 Scopus Traps but require exact frequency and multiple locations to be effective; Vicoustic Vari Bass Resonators which have an adjustable 50hz to 100hz range; and RPG Modex plates which are hideously expensive.

Danny/Tyson/Early B.-
I have a way that I think may work to confirm or deny the Rythmik PEQ addressing the problem frequency.

Remove 8033 from the system.

Set A370 PEQ OFF;  bandwidth at minimum; Gain at -12 db; frequency at 30 hz to start.

Play Qobuz Bass Tests Vol.1 30 hz track. (recording contains test tones from 30hz -100z at 5 hz intervals)

Set A370 PEQ ON.  Record effectiveness at listening position and rear corners.

REPEAT for 35 hz, 40 hz, etc.
 
Does this sound reasonable?

[Tyson]

It'd be a lot easier if you just measure the bass, it's actually super easy if you have a smart phone.  Do you have a smart phone?

[Danny Richie]

The PEQ should alter things quite a bit.

The key is to be able to measure what's there to see where the peaks are and by how much.

When we exhibited with those speakers we ran a pair of sealed servo subs in the back corners of the room playing 25Hz and down. There was zero room related issues. Bass was tight and clean down to the teens.

[bernardo]

Tyson-
My wife has a smart phone.

Explain to me how this would work. Only options for playback on my system are CD Transport and streaming Qobuz. So what will I be measuring - dB level at the various frequencies at the LP and corners? Looking for over the top dB level to determine the frequency? You'll probably laugh at this - I do have a Radio Shack SPL meter.

Danny-
Thanks for the input. This was more what I had in mind for this post.

"The PEQ should alter things quite a bit." I have not experienced this yet.

[Tyson]

Tyson-
My wife has a smart phone.

Explain to me how this would work. Only options for playback on my system are CD Transport and streaming Qobuz. So what will I be measuring - dB level at the various frequencies at the LP and corners? Looking for over the top dB level to determine the frequency? You'll probably laugh at this - I do have a Radio Shack SPL meter.

Danny-
Thanks for the input. This was more what I had in mind for this post.

"The PEQ should alter things quite a bit." I have not experienced this yet.

The good news is a smart phone and Qobuz is all you need to get good measurements. 

Smart Phone

If it's an Android phone then download the app called Spectriod - https://play.google.com/store/apps/details?id=org.intoorbit.spectrum&hl=en_US&gl=US

If it's an iPhone, download the AudioTools app - https://apps.apple.com/us/app/audiotools-db-sound-audio/id325307477



Qobuz

Nice, Qobuz is what I use, too.  That makes it easy.  Search for the album titled "Pink Noise" by the artist "White Noise Spectrum".  Here's what it looks like on Qobuz:




Measuring Process

1. Play the pink noise track through your stereo.
2. Open the AudioTools/Spectroid app and select the FFT option.  It should give you a live readout like this:






As you can see, I had a big hump at 50hz that I needed to deal with, which I was able to reduce using the PEQ function in the amps.