Bass Traps etc

Iain

Thanks. I guess the equipment is optimised, will investigate acoustic treatments and will report back.

Cheers

Steve

I have my system set up in the attic. It's a large room in a victorian house, floor space approx 50 sq metres. Speakers are DBL's. I had all sorts of problems with this room, due to the sloping ceilings creating corners everywhere and the large amount of maple flooring. I looked at all sorts of treatment options, but most of them seem to involve huge slabs of foam placed in the corners of a room, which is fine if you have space, but the foam slabs are not tuneable to specific frequencies. They just assume that most rooms have problems around 80-90 Hz.

Eventually I came across Absolute Audio, a company who design and make their own bass traps, mainly for recording studios, but they are now moving into domestic hifi and home cinema. They sent me a CD of test frequencies and the plan is that you observe the behaviour of your room and then Karl at Absolute will calculate which frequencies are the problem ones. My room proved to be so confusing that in the end Karl came and measured the room with his laptop and an white noise generator. As well as frequency response, he can measure the decay of the tones in your room. The nightmare showed up in my room as a 4 second reverb(!) at 63Hz, which in musical terms means that in a typical rock track by the time the drummer plays his fourth bass drum beat, my room is still recovering from the first beat!

The tubes are 4ft in length, about 4 inches diameter, and are placed in corners, or tucked away behind the sofa. They are tunable to whatever the problem frequency is, which keeps the cost down. They are available covered in fabric, or you can paint them. I'll try and get a digi photo posted. The whole treatment in my room (which was a lot more than would be required in an average sensible listening room) cost less than £500, including Karl's visit and fitting.

The end result is more bass depth, more slam, and the system is now fun to listen to for long periods.

If your interested in checking the test CD through your system Karl can be contacted at Karl@absoluteaudio.co.uk

Regards,

Mick.

I have succesfully used bookcases standing in two corners. They are oriented in 45 degrees to the walls so there is a triangular space behind each bookcase. The bookcases can be used for records, CD:s and stuff, so they aren't a waste. If this seems to work, one can then throw in damping material behind the bookcases for even better efect (anything works, old pillows, clothes or, of course, glassfibre).
If you happen to have bookcases around it's relativly easy to try, if you don't like the result it's reversible.

I've sent you an email about room treatments. I certainly wouldn't get any other speakers until you've got the SBLs sounding right - they are tighter and faster in the bass than most others. I think Mana SoundBases under the speakers would help.

Alex

I've found bookcases filled with books to be very effective in room resonance control.

Hi there Steve.

Interesting post indeed. I've recently moved into a new room and am playing with acoustics a bit. I've also been experimenting with my old REL sub as well - just to see how it does or doesn't work with the rest of the system - and one of the notable things that it does is that it flattens the in-room bass response. It makes some sort of sense but I wasn't really expecting it. This isn't going to work for everyone - it takes a good while to get it right and many people give up before they reach 'the magic moment' but it's a viable solution. I've set mine up to roll off around 36Hz, so it's well below the crucial PRaT zone, and out of the way of most of the music (to avoid over-thickening the musical soup) but it's now working pretty well indeed, giving the sort of deep bass that you just wouldn't get any other way...

Other things I've tried: Mana under speakers (works by basically tightening up the bass, reducing overhang and bloat - therefore what bass there is doesn't thicken the soup and excite the nodes too much), careful arrangement of furnishings (one fabric sofa, one fabric chair and one larger leather sofa) and better cabling (with similar effect to the Mana; together making a BIG improvement). That's after a bit of careful speaker positioning...

Have I hit 'the optimum' - not by a long chalk. I feel I had the room issues sorted more effectively in my old house, and the extra room space means that the bass is fuller, which in turn leaves more to 'get right' - which is tricky.

The next mod is to experiment with something absorptive behind the listening chair (the low leather sofa) - but I haven't yet found the right, domestically acceptable (aka: WAF) 'something' - any thoughts?

TC '..'
"Girl, you thought he was a man, but he was a Muffin..."

Hi Steve

I had very similar fears as well when I set up my system in an even smaller room than yours : 9ft 3" x 11ft 3".

The suspended floor is what's causing the boom and I'm afraid it will remain as long as the SBls do not have a solid substrate backing them, (back wall and floor : preferably solid wood for the floor and solid column concrete for the back).In my set-up, the SBLs were placed along the shorter wall, but they boomed even after installing acoustic treatments... and I eventually found out the culprit was the rather unsolid short wall they were up against - each time the bass arrived, the wall would resonate forever... (The Mana soundbases might help, but I am skeptical because without a solid foundation for the mana in the first place, whatever speaker it supports will suffer.)

The SBLs eventually ended up against the long wall instead, which was much more solid (use your fist and bang the wall for a listen : if it's really solid, it will not ring, giving a dead feel, which the SBLs love. If it rings and resonates... time to shift the speakers elsewhere) Placed against the longer hard wall, my SBLs gave a wonderfully tight, tuneful and weighty bass, with no trace of boom.

Unfortunately, after the money's spent, boom can still be caused by several factors :

Untreated corners
Bare walls and floors
Soft walls and floors
SBL speaker set-up (are they level, cabinets properly aligned, mid-bass should rest only on tips of loading cabinet spikes without touching the gasket)
SBL positioning relative to back and side walls
Equipment supports (make a huge difference...)
Cable dressing (can't stress this more)
Naca 5 speaker cables coiled in loops
Naca 5s 'cross talking' with power cord cables
Naca 5s touching the floor(suspend them, it helps)
Shared adaptors/electricity for power cord plugs
(dedicated 32A spur, 6mm gauge wire, fuse all cords into a hydra arrangement, and in my case into a 15A fuseless round-pin air con plug)

All these I've found to adversely affect the bass performance of the SBLs in particular - a pain I know, but what's a hobby? See to each of these (you'll be sweating and cursin' by the time you do), and you'll get exceptional bass quality you never thought the SBLs were capable of, and that's just at the end of 52/135s/CDS2...
I kid you not.

SL2s... I had a fortunate private audition of them yesterday, fronted by a 552/500/CDS2 on Fraims..., and though they were still relatively new at 2-3 months and running in... they already gave more than a glimpse of what they could do : they will plunge deeper than the SBLs definitely, and play louder without any sense of strain, but it was in the highs where they took the honours over their predecessors - really refined and detailed, but the overall sonics still shoving in the boot where it mattered and whenever required, without the harshness or strain. They were very well built and "chunky" in terms of quality - there's nothing "flimsy" or short-changed about the SL2s.

In a sense, with their bass capabilities, the SL2s for your place might rattle the floors even more... still if they're your overall cup of tea... I would heartily recommend them (except for them awfully thick foam grilles... gosh!)

As for the room : curtains, pillows, bookcases are cheaper alternatives, but I would suggest trying RPGs from the States, well worth the expenditure; especially the "Diffractals" and "Skylines".

Good listening and tweaking, the music's groovin' frightfully more.

Rgds

Philip

naimniac for life

Hi Steve. Many good advices here about damping corners which I know might be very helpful. One other thing i know ( by personal experience ) might help if you have wooden floor is to be found on www.sonic-design.co.uk. Good luck!

Sorry! www.sonicdesign.co.uk it is.