Using 15 feet of speaker cables is no big deal as long as the cables are a thick gauge. I don’t think that you would need a balanced phono preamp and IC’s if you decide to go that route. I don’t see any problem using the speakers on the long wall as long as they sound good. Set it up first before you change anything. The only cable that should be short is the one that goes from the TT to the phono preamp!

You definitely want the TT to Phonostage short. Secondly it is good to keep the speaker cables short. A very common solution is to place the amps close to the speakers and move the rest of the equipment to the side to keep it from interfering with the speakers imaging. 15’ is not to far for single ended interconnects. But if it allows you to get a better preamp…we’ll, better is always better.

What does your venue look like? Speakers? If you put photos of what you have so far under your UserID it would be helpful in allowing us to envision your space.

I'm running an ESL system, long wall, in a 7' x 10' x 24' room. Tried to make it work the other way, but speakers on the long wall just seem to sound better.

Agreed that cartridge to phono stage is the important cable. Really, I can't tell the difference between ultra-short speaker cables on the right and 10 footers on the left.

The long wall is often the best wall.

Ok..Added photo.

Current thinking..upgrade phono preamp to Rega Aura, or Whest with balanced outs and use Audioquest 3 meter XLRs and place integrated just forward of RELs.  Not ideal but this room is a bit narrow and Wilson likes 1/3 2/3 placement with listening at 1.1x speaker separation.

I should add that Shunyata Everest 8000 and Sigma power cables arrived today and made an incredible transformation of the sound.

always better to use long interconnects and shorter speaker cable

I like my equipment (TT, CDP, streamer, phono stage, preamp) well away from the  speakers.  To accomplish this, I went with a long connection (30 feet) between amps and preamp.  It works fine as long as the connection is balanced.  Don’t try this with an unbalanced interconnect

Setup Speakers Along Long Wall - room with sloping ceilings

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Your question no 2:

Unfortunately, I cannot see your pics.

Conditions in a room with slope ceilings are far from ideal. Initially, I had my speakers placed in front and under of one slope side. SQ was very bad. So I changed the speaker position to the front end wall. After some meticulous position work respecting the accoustics of the room, I am now satisfied with SQ. It turned out that nearfield listening is the best way to follow in such room. As good as it gets.. Although, Big Band Sound and Classical Orchestra Sound is poor (relatively low ceiling heights, see pics)

Answer to your second question: with speakers on long wall in 12 ft wide room, your back ends up against the wall. Basically impossible to get any control on behind your head reflections that way. Diffusers won't work that close behind you. Ideally need 8 ft or more behind you to get the best sound. Just my experience. I would stick with the short wall. 

That’s how my Tannoys are set up, along the long wall...had no choice. Luckily they sound good there. I still have about 5 or 6 feet behind my couch before the back wall. 

With the potential cost of good cables, I might first look into what’s going on w/ your turntable & why there’s a problem ? I use that cartridge but not familiar w/ the Technics. My Basis table / Vector arm is likely substantially better than it but it’s pretty close to to my speakers which I play loudly & have no issues. There are many fine, not crazy expensive turntables now w/ good suspensions that might work well. There are also many types of “after market” fixes to put your turntable on that might work too. I’ll guess there’s a thread on this site that addresses this. Just a thought. 

Long interconnects are always better but over 15 feet should be balanced.

NEVER put a listening position against a wall. Somewhere within the middle 3rd of the room is best. 

Check out the posts that mention AES48. My gear supports this so I use 15 foot Benchmark XLR’s that are low cost and sound excellent with this supporting gear. If If I was able to put a hole through a Livingroom wall I would use 50 foot XLR’s to get my rig completely out of the room.

Luxman gear, for example, does not support this standard and I would not use my Benchmark XLR’s with that, nor would I keep my amp(s) so far away from the preamp. First of all it would be very expensive to buy commercial grade XLR’s and I do not have confidence it would be good. Pro gear such as Weiss, Benchmark, CODA, and I think, Bryston support this.

One thing I noticed with LONG wall speaker placement in my Livingroom was that the speaker just 1 foot from the front wall was OK. I think this is because I have 7 feet to my left side wall and 5 feet to my right side wall. That right side wall is a partial wall that opens up to the family room. I also have 25+ feet of ceiling height in the Livingroom. All of the LONG wall space is what likely makes the sound work with a floor stander so close to the front wall.

In my last home, I used the long wall and ran the speaker cables under the floor. I’m a firm believer in not going long with interconnects, unless you are using XLR. And then only if there is no other choice. 
I did notice the lack of sidewall reflection and I grew to like it.

All the best.

JD

Nice system. A great looking room.

Looking at your system my guess is the subwoofers are overloading the room with bass. I assume with the subs turned off you do not have the problem with the turntable? I would start here. 
 

I am fortunate to have a large room. As @curiousjim points out, having wide spaces on both sides of the speakers can be good. You’ll probably need to heavily dampen  the front and  rear walls and the ceiling. It is worth a try… but I would first figure out how to stop the feedback. 
 

I’ll give it some more thought. I am sure with the additional info you supplied, there will be some folks that will have helpful suggestions.

If it were me in that space, I'd still try and utilize a short wall setup. It's a nice looking room with nice gear. I would first try a wall shelf to the side of the window for the TT, as it would be behind the speakers and possibly help with isolation from the floor, which is obviously suspended. If that still proved troublesome I'd look into isolation tables, to put on the wall shelf under the tt, from basic passive units, to high dollar active. Additionally, I'd really limit the subwoofer setting, place them outboard the speaker stands for space, and move the rest of the equipment low against the wall under the window. I see you've got some treatments, which is a good thing, many people overlook this crucial detail. I'd hazard to guess the interactions with the turntable are from the floor and not airborne, but I could be wrong there. You'll just have to try Jenga a bit moving stuff around to get the best compromise. 

I don't have cartridge feedback with turntable located as in picture.  I talked to the Wilson people and they prefer the speaker location as is, so I'm looking for a preamp with balanced out and 3 meter XLR interconnects.  My dealer suggested Whest, or Rega Aura and Wilson dealer suggested baby Boulder.  More bass traps on the way.

Go long young man!

Just looked at your setup. Nice equipment! After looking again at the picture, I would definitely cover the window with something and after your bass traps come, take a couple of those absorbers and place them on the ceiling above the speakers. Maybe a bookshelf or two or something on the right wall? 

Did you do any calibration when you setup the Subs in the new room?

All the best.

JD

I'll be using a covering for windows, but nice view, so will only do shades.

Absorbers over speakers and to side and front of couch will be added once speakers are in place.

Calibration ..no.  I have an Anthem pre in theater room , so have equipment but can't get calibration file for microphone from anthem.

Answer to long versus short interconnects versus speaker cables. Long interconnects are okay if you have high impedance system. Balanced helps but is a desperate measure And, you don't have a high impedance system. Consumer cables are 3x interconnect and 10x speaker cable impedance typically. This is wacko impedance but that's the market. Therefore short interconnects are always indicated in audio systems but try it yourself and you will see

Answer to long versus short wall. More important is room symmetry and acoustic insulation.  Then you mentioned the feedback due to standing wave room residence on your turntable. That is hit and miss and I'm afraid you're on your own with trial and error about that. As a beginning remedial measure I would insulate the entire wall and sides behind your speakers for a live end dead end effect.

I appreciate and will try to take the above advice in that it makes sense to me.

The balanced phono preamp that I was looking at isn't available until November, so I'm going to buy more bass traps, lower my turntable rack and see if I can keep my interconnects short.

Recording studios will sometimes use long interconnects without worry. I've had to deal with all the size shape and position issues you mentioned and cable length has never made a noticeable difference. Speaker cable length also didn't change sound (using 14 or 12 awg). Booming sounds more like room nodes. When you say more bass traps, are you using thick insulation style traps? Have you tried moving the speakers one or more feet in each direction? Cheap tweeks to try first!

15 foot speaker cables aren't a problem. I use them with no ill effects.

Once you've solved the pesky low-frequency rumble, you won't have to worry about how to position your equipment. This is a great way to completely solve the problem. You can use the Energy-Pump power cable with your power amplifier. It removes low frequency rumble on many systems.

In a large proportion of audio systems, the low frequency rumble is produced by the uncontrolled mechanical inertial vibration of the speakers because the power amplifier does not have sufficient control. An Energy-Pump power cord can solve this problem. Why not try it out? If it doesn't remove your troubles, you won't have any cost.

The problem comes from the energy put into the floor (2nd story) by the REL S/812 subwoofers.  I solves it by placing the turntable in the corner where floor vibration was at a minimum.

Typically the problem comes from footfalls on a hung floor. The solution for many decades has been mounting the turn table on a wall mount. There are many such solutions on the market. This will allow you to place your turntable wherever you want.

From my experience I agree with Baylinor. When setting up my room (using the long wall for placement) I was not able to overcome the reflections. Heavy speaker toe in made things somewhat listenable at low volumes but everything fell apart afterwards. I have no direct experience with using a turntable in this regard.

Rotating to the short wall, applying heavy window treatments and moving the speakers further into the room made all the difference. Ultimately I added diffuser panels, one on each side wall and one on the ceiling to tighten everything up. Since making these changes the only improvements have been with my adjusting seating position forward/backward but I only do this when auditioning new equipment.

I typically prefer long wall speaker placement. Often long wall placement will improve bass response and provide a more spacious sound stage. There is one very important caveat; if the listeneing position now becomes close to the back wall, absorbent room treatment behind the listener is needed to avoid comb filtering effects.Thick foam covered with natural wool works very well for this.