Looks like you have Bottlehead amps. That's a pretty good combination; I like the sound - plenty of volume with full bass and pure mids and treble. How does the system sound to you?

OK, the sound, well I have to say that on initial start-up I was disappointed with the results of all my hard labour. The sound was dull, dynamically restrained, with a shut in quality to the vocals, with the overall sound best described as small, bass had a thrummed quality rather than well delineated and was not too clean - not a good start to say the least. So, do these need to be run for a period of break in?

I connected them to my AV amp and used a CD system 'burn-in' track on repeat overnight and throughout today. This evening they are far better, there is more punch to the sound, things like 'mark trees' have a real shimmer to them and Hi-Hat rides are clearly discernible from normal cymbal strokes as are both rim and centre strokes. Vocals are open and detailed with good timbre and emotion, a vast improvement on yesterday and I’m far happier. The only issue is that thrummy bass – most of the time it’s fine so I suspect this is a room interaction. The problem would appear to be in the low 100hz region (110-140) at a guess, but I’ve no way of really measuring this, but I suspect a DIY panel resonator will be on the cards shortly, though I’ll wait until I feel the speakers have stopped changing. I also suspect a MagneQuest transformer upgrade wouldn’t go amiss to aid overall control as well.

I don't know if any of the above has been noted by other builders, but the change over the last 20 hours has been quite dramatic to say the least!

Paul.

I'm sure you've done this but I'll suggest it just in case - it never hurts to double check connections - Check the wiring and make sure the bass bin, midhorn and tweeter are all connected to the right outputs on the crossover PCB and also make sure they're all phased properly.

If you connect the midhorn to the bass bin output and the bass bin to the midhorn output, it will sound pretty unnatural, but you might not catch it right away like if you reversed woofer and tweeter connections. You'll still have bass and midrange if cross-connected, but the bass is weak and the midrange is hollow sounding and rolled off early. So check that and make sure it's right.

Also, check the polarity of every connection. The midhorn and tweeter in particular, if phased right sounds like a single driver, if not, sounds like the tweeter and midhorn are independent of each other, you can really hear the disconnect. So check everything and make sure it is all connected properly.

Paul

As an aside, what kind of floor and walls do you have?

In America, many homes have concrete slabs and walls are drywall mounted on wood frames. This is pretty good because the concrete slab is non-resonant and the drywall vibrates enough to damp room modes.

Two kinds of rooms cause the most trouble:

1. Rooms with hardwood floors suspended over a crawlspace. This makes a resonant chamber with the floor acting like a drum head. It's impossible to get bass right in a room like this without doing something to fix the resonance of the suspended floor and crawlspace.

2. Solid concrete walls like in a basement room form well defined room modes, and that makes damper panels and/or multiple subs a requirement for good bass sound. I have also seen plenty of homes with plaster walls that are rigid. This is like concrete and doesn't provide much damping.

If you have rigid walls, these may help:

• "False wall" bass trap panels for concrete walls

The room itself would appear (based on it's dimensions) to have a modal region between 32 to 177Hz with no multiples but some close clusters in the 60's, 90's and 130's and it's these I feel I need to tackle.

I aim to build a 4'x 2'x 4" (WxHxD) panel trap and site this between the speaker, but clear of the wall by about 4 inches, as this is the only easy place to put it - I've got quite a lot packed into this room! I don't know if this will really help, or even if this is the real issue, but the speakers would be more likely to go rather than undertake major remedial work to resolve this issue.

Paul

Best thing to smooth room modes is multiple subs and/or room damping.

Bass damper panels will improve damping, and that's an important way to smooth room modes. Since every boundary of your room is very rigid, I think damping should be added regardless of anything else you do. No speaker can really sound good in the modal region, at least not a single speaker or a pair. They'll either be weak in the bass and so not energize the modes, or they'll put enough energy into the room to make those nodes stand out like a sore thumb. So I think damping panels should be done, no matter what other steps you might take.

Since you say your room is packed, I'm assuming that adding a couple more woofers isn't an option, but if it is, it's another good solution. A couple of LAB12 woofers, each in a 4.5ft3 cabinet, added to what you have now would greatly smooth the modes. You could easily model the room with CARA, trying a few positions to find where energy distribution is smoothest.

Either panel dampers or multiple bass sound sources will provide improvements in the form of smoother bass, but both together will most certainly provide the best bass possible.

The speakers are still getting better by the day and I've just had a musician friend round who was thrilled by the sound. I still aim to put together a bass resonator (should have enough material in stock as it were) and maybe look to some foam bass traps for the corners a little later.

Paul

One of these times, if you're inclined to experiment, grab a copy of CARA and model your room. Place woofers in various places in the room to find what makes the most uniform response. Simulation takes just a few seconds, and it will show the modes in the room as a function of frequency. It even makes an animation to demonstrate the modes with a simulated frequency sweep.

I would start by placing the two additional woofers in different positions in all three planes. One configuration that seemed to generally work well for me was to separate woofer pairs by a few feet, one higher off the ground than the other. Try other configurations too.