How many subs?

Thanks for all the info.  I like the Debra system and the small magic box.

A sound guy worked in that room for hours moving 4 subs around and decided 3 was what is needed.  He used all the necessary gear to work it out.

Probably what I am liking when using only 1 sub is Rel's blending of sub with main speakers which are stand speakers.

The stand speakers are back to full range which also sounds better.  I just couldn't balance the mains with the subs when separating the frequencies sent to each.

I wouldn't use DSP if it had to involve the main speakers.  I have a very decent CD transport, musical R2R DAC and tubes at the front end of my amp.  Running that through digital and back again seems not the best idea.  But using DSP for bass?  I am using DSP - it is delays for 2 subs.  And the left sub never has gotten DSP.

The plan is to try the 3 subs again, but while considering the front left as the main one.  A combination of using Rel's preferred connection method for the left, running the stand speakers full range and less of the delayed subs might just hit the spot.

I don't know if I'd have 'gone so hard' with making a hifi room now knowing the difficulties with low frequencies.  But hey I'm here now so I need to get the best sound from it.

I have gotten further.

Front left - Rel high input using L and R as the main sub with stand speakers full-range - as I said I would do. The sub against the right wall (I think 3 ms delay), being nearly opposite the main speakers wasn’t doing it for me. Only having the back right (9 ms delay and 180) seems to work well with the front left.

I can hear ’a hole’ in the back left in bass. But it is a difficult room. 14 feet by 12.5 feet (that being the front wall) by 11 feet. The difficulty is a diagonal in the back left corner, amongst other standard difficulties.

I haven’t been using a low pass filter that is necessary as the 120Hz 4th order low pass on the Rel theatre inputs aren’t enough to remove higher frequencies. I want to sell a piece of expensive equipment that could take care of this. I know the driverack can create an appropriate low pass and I am hoping it can combine L & R to 2 mono outputs so I can properly test the 3 sub design. I am waiting on someone who can program it.  For the moment R is the input for it.

I can easily change it from L & R to all subs to L to the left sub and R to the right sub(s) by disconnecting a wire and removing a cable - once the driverack can accept L and R and make it mono.  I could buy a Radial Mix, but as I just sold 2 of those, I prefer the driverack to be able to do this.

Thankyou m-db

I have a friend who is bemused about my attempts. He reckons he’ll come round and fix it without using delays, and with just 1 sub.

I know people are saying use 4 - but if it sounds artificial and I don’t like it, and I am determined to not use standard DSP - what can you do?

The driverack is for aligning 3 way stereo systems in large venues - or providing back delay onstage.

The acoustic engineer studied how to manage low frequencies in a room - so I don’t understand why his method of using delays would seem to be not at least an option.

The subs I have are Rel S/510 - it was what was recommended for my stand speakers which now people might be curious about - B&W 805D3. That was a good choice of main speakers for my room. I know some people don’t like B&W tweeters, but it would be boring if everyone liked the same things.

I also have an AVAA (I have more but selling them). Their party trick seems to be to lessen the time a sound bounces around the room. This is below approx 150Hz.

Cheers everyone.

Everyone knows I'm going to still give the delays another go - even just to better understand I don't like it.

From my engineer:

"The method I used for setting up the three subs wasn’t with all subs at the same loudness (in my opinion it isn't correct due to different distances from the listener and other factors...). I used a method, which slightly varies the dB levels between each sub to achieve a smoother in-room response. This approach focuses on reducing peaks and nulls caused by room modes while maintaining overall balance."

The original subs I chose were lesser Rel subs.  I gave instructions to where I bought them is I cannot have the deepest bass due to neighbours.  I am already aware that they can hear what is happening.  I want to have some hope of being able to play music.

It is Rel that paired their choice with the speakers.  The S/510s are needed to keep up with the 805s.  They insisted that TX7s or whatever I chose weren't good enough.

I installed just over 3 inches of acoustic treatment along the party wall in the hallway, lounge and kitchen - 4 layers, including 3 layers in "acoustic-board" specifically designed to reduce vibration.  With the double brick, I estimate (and because I can no longer hear the neighbours) I might have achieved close to Rw + Ctr of 60 dB.  But that won't stop low frequencies - nothing can completely stop them unless we go with "in space, no-one hears your subs."

The room is separated from the hallway by a brick wall with plaster on each side.  The front window got a double glazing upgrade using a material that isn't glass and with a large distance between them.  Then theatre blacks - 95% wool curtains.  This is the front wall.

Acoustic treatment (above ~200Hz) around all walls which surprised me how much it quietened noise from outside.

With the acoustic door - that room is sealed tight.  Acoustically and thermally.

Even with all this - I can't have subs that properly do 20 Hz.

@m-db

The Rel subs have to be on the floor - another disadvantage.  I tried platforms and it really sounded much worse.

Subs that can be decoupled from the floor, with proper bass extension, and ability to knock some lowest frequencies out of the mix when playing particularly annoying bass heavy music, looks like a good solution.

The sound track to Blade Runner - CD (probably all formats) has some excellent bass moments.  It would be great to hear that with fully capable subs.

I like that there is a preset - 6 - that is too much.

You always need a preset that risks causing an earthquake.

@jayctoy any number of subs is good - I just got the 3 sub system going with some outrageous hardware. It sounds fantastic.  Not the lowest bass - I don't want that (yet).

Delays with a Drive Rack. Low pass filter for the right subs with a CR1 - nothing spared.

I need some tweaks to get it right.  When you hear a Tyrannosaurus Rex on S/510s - you will run.

Everyone will be pleased that the experimentation with delays for subs 2 and 3 is done and it is a fail.  It takes a few sessions and many tweaks of levels to hear what is happening.  To get the sound so subs 2 and 3 don't noticeably interfere with the main speakers is a very low level.  I turn off output 1 on my amp and listen to only output 2 which feeds the 2 delayed subs.  Really not a lot happening.  Not worth it.

@m-db  the drive rack was not used for purpose, it was what it could do.  I wanted a balanced product that could give delays up to 10 ms (not including latency).  When the Acoustic Engineer said 3 ms delay there and 9 ms I got someone else to program it because we could not work it out.

I cannot use Rel's preferred method of connection for sub 2 and 3 due to the delays so it is the 0.1 input or whatever it is called.

Then the problems with the 120 Hz 4th order low pass filter on the subs - it is worth mentioning again - this is not the filter for hi-fi.  Too much higher frequencies.  I have the JL CR-1 to fix that.

Is today today?  Good it is.  3 days for suggestions for testing.

I now have only 1 sub. No delays. No DSP. It is in the front left corner and 180 degrees out of phase. It uses Rel’s high level input from both L and R.

I found whatever I did, multiple subs interfered with the sound from the main speakers.

It sounds great - that is what counts.

What has become apparent, is my floor.  Vibration through it.  A timber floor with construction involving stumps. I have plans (that will likely be never done) of removing the carpet, ripping up the floorboards, removing the structure, levelling the ground and then preparing it for a concrete pour. No formwork is needed as the brick foundations of the walls will provide that.

I haven’t looked into if it actually needs rebar, but I’ll go there and have fun making it up as I go along. After watching a 5 minute video on YouTube of course. In addition to what might look sensible, I’m going to incorporate an immature shape into it and know it is there.

I have a couple of friends that can weld - they would find my plans funny. Both know about concrete foundations so I don’t need to waste 5 minutes on YouTube.

Then open up a window, get the 2 (?) concrete trucks and pour concrete through.

Floorboards back on top and carpet. It will likely still need a lesser form of joists between concrete and floorboards - or I ditch the elderly floorboards and use something else.

I could lower the floor which makes the possibility of tripping into the hallway at some point likely which I approve of and I think everyone else would too.