Dynaudio c2 or c4 - need some help

That's a very reasonable plan. Two subs would be better than one and I think both F110 or F112 would do great.

Double dry wall green glue recipe is great to sound proof the room but does not always produce the bass quality that you like. It will reflect more base than single layer contruction but tough to know whether this will be to your taste. The doors and windows are also large variables in this game. I recently blocked all windows (removal solid panels) and got new 1.75" sound proof door. Bass reverb was out of control. Some windows partially block worked best for me. Very difficult to trap bass freqeuncies under 80Hz.

Certain amount of bass leakage may not be a bad thing and may even alleviate modal problems. No room is perfect.

A lot of this is unpredictable. If possible, measure and listen to the room before the finishing touches and adjust as needed. Leave some room for traps and diffusors.

A certain benefit with your plan is a very low noise floor, which is always good. My room noise floor was about 50db depending on wind. After new door and window panels, it is into the 40s. There is a tomblike silence which expand the dynamic range of the room without busting your ears. A very quiet room needs more attention to diffusing slap echo to good effect.

Good luck on this long journey. I think you will like the end result.

Not just the room size but the ratio of the dimensions.

Dan, is it going to be HT room too?

yes, will be for ht as well. Will have solid door (sourced from acoustical solutions in Richmond, va). Might do the same as u on the windows -- will see once in and listening.

In terms of ratio, exact size is long walls each at 18'6" and two short walls each 16'9". Ceiling is 7'8".

Going back to original questions, the C2/C4 vs C1 would really depend on whether you like the stacked design or not.

The extra woofer towards the top is another bass source. When combined with bottom woofer, theoretically yield a more even in room bass boast due to markedly different speaker-boundary interaction. Whether this is going to work for you is difficult to predict. You may try modeling with RPG room optimizer to see which yield a better response within your practical constraints. Interesting to me that Dynaudio going a marked different driver arrangment with new flagship.

More drivers/larger cabinets will usually yield higher sensitivity, higher jump factor and move more air. Most dynaudio are better off with SS. It's not like you can do tubes on the bigger ones. C1 is cheaper with much easier logistics. C2 better deal on used. All need subs especially HT. For music, you may be crossing over to subs at lower freqeuncies with the larger speakers. It may reduce the audibility/conspicuity of the subs.

You may be able to choose listening position to minimize one to two primary modes. My guess is that would be sitting near the center of the room. You will be pretty close to the speakers which some people like. However, nobody like nearfield TV watching : )

Dangelod,I have heard the C2's and I do own a pair of Dynaudio S5.4's..For my size room 13x21x8 vaulted the 5.4's are perfect..I also run double subs with them and it is perfect...I too am looking for the day I pick up a pair of C4's for more of that Dynaudio magic.C2s or 5.4's with 2 subs would be nice for your setup...
Also look into OCOS speaker wire for the Dyn's.They just shine with it ,and is also recommended by Dynaudio..
I use a triple run to my speakers...A good rule of thumb for OCOS wire is 8ohm (1 run),6ohm(2 run),4ohm(3 run)but it is also up to you ears and the sound you like.

Here is a quote form this person from a past forum:

04-26-08: Matteiser
Im a Dynaudio dealer so maybe I can offer a comparison as I listen to these on a daily basis.

The S5.4s are a true 3-way design utilizing the incredible Esotar2 tweeter. Very smooth and detailed and incredible bass output. These will play loud and not strain doing it. I usually represent it as an music lovers/reference home theater speaker.

The C2s are a step above in transparency top to bottom. I find the highs to have more extension, the mids to be more transparent and open, and the bass to be tight and responsive. It wont play as deep or loud as the 5.4s, but its a better music speaker IMO because of the increased resolution.

The C2s tend to disappear better than the 5.4s too. You can close your eyes and they transport you to the live event better. The Confidence line incorporates the DDC driver configuration which eliminates up to 70% of floor and ceiling reflections which can really help in some rooms. Though the drivers look similar, the Confidence drivers have a more robust motor structure, which coupled with the more exotic cabinet construction, contributes to an overall superior speaker.

However, both speakers are spectacular. Dynaudio uses very similar crossover points and driver technology between the lines so they all share the house sound. If you are building a reference 2-channel system, the C2s are better in my book. You might even consider the Sapphires which combine the transparency of the C2s with the low-end authority of the 5.4s.

Hope this helps.