Help define my listening room size for speakers

Gee whiz, my room is similar to yours and I also sit at about
7-8 feet from the plane of the speakers that are about 2 feet at most from the wall in back of them (except I have more room to the sides, as they speakers are on the long wall).

I had major boom or lower midrange overload with big VSR 7s and also Piega P10s and had to sell them. Wilson WP6s worked just fine with no booming (sold them because I didn't like the
vocals, but that was true of the WPs anywhere for me).
The speaker I had longest and worked fine there were Aerial 10ts, along with Apogee Stages. Now Harbeth SHL5s work perfectly there. I still may move on from the Harbeths because I want more resolution. Oh, I also had Kharma 3.2s there for a while, and they were fine with no boom or other room-related issues. Long ago, I had little Celestion SL6s there with no problem.

I used a Pass X350 with the Aerials, now an Edge NL12.1.

So I think your room is OK for a lot of speakers, don't worry too much.

Before new speakers it is time to move things around. Try taking the large cabinet on the left wall and put it on the wall the speakers are on. Bring the speakers out to accommodate that. If the cabinet is too large I suggest taking it out of the room for now. Less is more. Also, add room treatments at the first reflection points on each of the side walls. It also might help to 'see' what your are hearing by using a free program like EQ Wizard. That program will enable your eyes to guide your ears. In summary, I don't think up sizing your speakers will really improve your sound as much as modifying the room layout and treating it.

Hey Thanks to the posters for the input provided so far. I will give that room EQ software a look as I haven't seen that one. It looks very interesting for sure.

Unfortunately I can't really move the speakers from the wall they currently occupy because the other 2 walls have issues of their own. I would certainly love to utilize the longer distance of that configuration though if it weren't for the issues mentioned below.

The one wall that runs along the staircase is really only a partial wall as it opens up gradually at the same angle the staircase follows. If I put the speakers in this location one of them (the left one) would be open in the back with no immediate wall behind it and the other speaker would have a full wall and corner loading that the other one doesn't.

The wall on the right hand side of the room has a window were one speaker would go and a bathroom door (not shown in drawing) where the other speaker would be.Damn, Im stuck

The bigger room in the drawing is currently "unfinished / under construction" with an undetermined completion time at this point (yeah, one of those projects). It would offer the best configuration of all but one fear I have with placing speakers horizontally in any room of my house is that it may cause me to have to limit the listening levels I currently enjoy (100+ db on those lively nights).

I think my neighbor would end up getting the full brunt force of speakers firing in their direction despite bass being un-directional for the most part. The way the speakers are facing now results in alot more shielding of the sound outside the house because there are at least 3 walls almost a foot thick in both directions before the outside wall of the house is reached.

I have thought very hard about having the Immovable Object wall taken down to resolve the problem but it contains an old chimney that is no longer used that runs from the basement to the second floor and would be a real PITA to demolish.

I would not worry about your room and go for bigger speakers. I am sure I am in the minority but a lot of times I think a smaller rooms sound better (I will explain my opinion below).

But first we all need to stop making blanket statements on these forums as start thinking about the physics. For example a 40hz wave at 80db from a 8" driver is the same as a 40hz wave @ 80db from a 10" driver. The difference is the larger driver will be more efficient and will most likely have less distortion.

Smaller rooms always sound more immediate and intimate to me. The only thing you really lose is soundstage and imaging (depending on the dispersion of the speakers). I value dynamics over soundstage and that is why I often think smaller rooms sound better.

The problem with small rooms is not the size of the drivers in the speakers but how low they reach. Bass gets pretty room dependent down low. Plan on about 4db-6db of bass gain from 20-80hz. So if the speaker starts out flat at 20hz it is going to get pretty bass heavy in a small room. But if a speaker is down 5db at 20hz is may sound pretty flat at 20hz (80hz traps will almost always help).

If you want good examples of this look at Kefs 207/2 Stereophile's "acoustic" and in room measurements. The Kefs are shelved down almost 7db from 40hz-20hz. But the in room is razor flat (one of the best I have seen). Then look at the "acoustic" and in room measurement Revel Salons, a speaker that goes acoustically down to 20hz but in room can get pretty lumpy. Having the back of the room open will not really help you much. The closest boundary is what really matter, front, side, and ceiling.

On the subject of seating distance. The only advantage of sitting farther back is driver integration. The total spacing of the driver will be the biggest factor. Adjustable driver housings and coaxial designs are ways around the problem. But really closer is better (with in reason). You hear more details and the soundstage will be wider/taller, all in all the music will sound larger (think of how big headphones can sound).

For the speakers you have listed I have only heard the Thiel 3.7 and 802Diamond (actually heard them in the same room/day). I wound not recommend the 802Diamond with your room. This speaker is already bass heavy and your room will only add to that. I have also heard the 802D (old model) in about 5 different rooms. They really sound best in a large rooms because of there tonal balance, room gain will only make them worse. The dispersion is also not very even and with the close side walls the in room tonal balance may be off in the mids as well. On the other hand if you like massive bass, you may like the 802diamond in your room.

Now the 3.7 is a different animal altogether. The tonal balance is flat to lean and could use a few db of gain in the bass. These will sound very good in a mid sized room, if you accept the fact that they will never meet their soundstage and imaging potential. Now Thiel recommend 8-12 feet as a seating distance to get time alinement. If you are sitting at only 7', sitting lower or raising the front spikes will help. But really sitting at 7' the Thiels will still be much better integrated than most floor standing speakers on the market anyway...

PS, I have always found sealed speakers to work best in small rooms. Port loading can get tricky and it is one less thing to take into the equation. The 3.7 would be quasi sealed and I believe the Andras (at least the newer ones) are sealed.