New guy: Lifelong 2-channeler trying 7.1.2? (1 Viewer)

[almico]

Well, the main issue is, it shouldn't make a huge difference in the overall audio and impact to turn on/off the center speaker. Something isn't right.

Levels and timing seem OK, it's just a drastic difference in the sonic dynamics of the speakers.

I had an inspiration this morning. If the Klipsch R-52C leaves me wanting, I think I can integrate an RP-8000f tower.

My original plan was to build 4 Ikea Lack racks and bought materials sufficient for that project. After building 3 of them I decided that was enough and stopped there. I thought it more symmetrical having the center speaker on the middle rack.




Now that that plan has hit a snag, I could go ahead and build the 4th rack and put an RP-8000F in the middle with 2 on each side, satisfying my OCD. One small issue being the racks are 42" high and the RP-8000F is 43". Not ideal, but not the end of the world.

 

[almico]

Making room...

The triple rack is screwed together at the moment.

Maybe the base of the speaker is removable? If so I could match the height perfectly. Found an open box old RP-8000F (not II) for $326 shipped.

 

[almico]

So I'm taking another dive into REW and doing some sweeps.

The following graph is what I get both with the subs on and off. The problem is the green one is with subs OFF. As soon as I turn on the processor the low bass drops out.




My Anthem sub crossover settings look like this:






And the levels settings:



When I use the level test noise to compare SPLs for each speaker, the subwoofer selection blows me out of the room compared to all the other speakers. But that's using regular pink noise, not low frequency noise.

I'm at a loss to figure out why the Anthem is pulling so much low frequency out of the system when the processor is turned on.

 

[JohnRice]

A couple quick things.

First, I'd set the LPF for LFE to its highest setting. Setting it lower limits the LFE channel, and no reason to do that.

Regarding the bass, you have a standing wave/cancellation problem. Solving that isn't easy, but it can be addressed at least. What model(s) subs do you have?

The Anthem isn't the source of the bass problem.

Does the Anthem have a separate distance and level setting for each sub?

 

[almico]

Regarding the bass, you have a standing wave/cancellation problem. Solving that isn't easy, but it can be addressed at least. What model(s) subs do you have?

The Anthem isn't the source of the bass problem.

Does the Anthem have a separate distance and level setting for each sub?

I definitely do. While I was playing with REW, I used another signal generator to run various low frequencies into the system. When I was running a 50Hz signal I could hear the base from the left Altec if my ear was in line with the voice coil and about a meter away. As I stood up the sound disappeared completely! I mean gone! If I moved farther away it mostly came back. If I towed the Altec in I got a big trough peaking at 80Hz. When I moved them parallel to the wall the trough was much less. Weird.

The Anthem has two balanced outs for subs.
I have 4 home-made passive subs.
I'm running one output to each of two Crown XLS-2500s bridged mono. One amp feeding the front subs and the other feeding the real. I can control the sub volume with the gain controls on the Crowns front to rear, but not left to right.

The Altecs are going down to 35Hz. The lowest setting on the Anthem is 40Hz. If I turn "off" the LPF on the Altecs and allow them to go full range, the subs are turned off completely. It has to be set at 40Hz minimum.

So I might not even need the subs...or the center channel at this point.

 

[JohnRice]

You're seeing the complexity of subwoofers, and the more there are, the more opportunity for problems. Integrating them into the room isn't easy. Unfortunately, the way it's all hooked up, it's not possible to correct it. Each sub needs to have individual phase controls at the minimum. In order for that to be possible, they can't share amp channels. It can be fixed by not running the amps bridged, connecting each sub to its own channel, and having a MiniDSP between the receiver and sub amps. Then comes a bunch of sweeps and calibration. Or... a receiver/processor that has four discreet sub outputs.

 

[almico]

You're seeing the complexity of subwoofers, and the more there are, the more opportunity for problems. Integrating them into the room isn't easy. Unfortunately, the way it's all hooked up, it's not possible to correct it. Each sub needs to have individual phase controls at the minimum. In order for that to be possible, they can't share amp channels. It can be fixed by not running the amps bridged, connecting each sub to its own channel, and having a MiniDSP between the receiver and sub amps. Then comes a bunch of sweeps and calibration. Or... a receiver/processor that has four discreet sub outputs.

Thanks! This is getting fun...I think. Tomorrow I'll try running one amp with R&L channels into only two subs and see what I get. I could also connect two subs per side in parallel. The amp can see 4 and even 2 ohms without issue. But then I would lose the "fader" adjustment front to rear.

 

[JohnRice]

Unfortunately, that's not what I mean. Separating the subs alone won't solve anything. It's just necessary so that you can correct the phase for each one individually, but to do that you'll need something like a MiniDSP.

 

[almico]

Good news and bad news. Bad news: The Klipsch RP-8000F didn't help much as a center channel. Again, the issue is not that it doesn't sound good, it's just not capable of replacing all the sonic dynamics and nuance that the Altecs offer when the center is turned off. Turning on the center channel just feels like sucking all the goody bits out of the room.

For example, I was watching Shutter Island and there is a scene when they are down in the catacombs and everything is damp. Condensation droplets are falling from the ceiling into the puddles on the stone floor. With the center channel "on", I hear the droplets plinking when they hit the ground. With the center channel "off", I find myself feeling the top of my head for the spots where the water is hitting.

I was naive when I decided to try surround sound as to just how a processor works. I assumed (incorrectly) that the center channel would be an "addition" of sound, not realizing that the main audio output would be transferred from the fronts and they would basically become effects speakers. Those speakers are just too good to only handle effects. The overall effect is less, not more.

So no more messing with center channels. Phantom center for me.

The goods news is that Adorama packed the "open box" Klipsch like crap and it arrived with a little damage, so hopefully it is going back, if I can figure out how to get it back in the box. Yes, the styrofoam came this way, just broken pieces shoved into the box:



Taking a step back, I bought this house 13 years ago for many reasons, but certainly not its audio/visual potential. It is what it is.

This is the space:



This is the rear:



It's an odd space in that it is 20' wide, but my listening chair is only 10' from the front wall due to the fireplace in the middle of the area. The front of the Altecs are only 8' from my ears. That's why spreading them further to squeeze in a center channel was probably a fool's errand in the first place.

As far as standing waves go, I thought I wouldn't have an insurmountable problem because the back of the room is a pass-through on both sides of the fireplace. Those long LF waves have plenty of room to stretch out. Maybe I still need to treat the upper triangles of the cathedral ceilings. For the front of the room I had a standing coat rack between the bedroom door and the left speaker that acted like a bass trap. It's going back and maybe I need to get another bass trap on the right side in the corner as well as some treatments on the walls behind the speakers.

After blowing the dust off my room mic and doing some measurements, it is very possible that I do not need subwoofers either. The Altecs are going down to 32Hz at -5 or 6dB and the only thing I loose is a little thump of an explosion or the lowest of notes on a pipe organ.

For highs, I hung that carpet runner behind my chair to help with reflections off the stone. There are heavy curtains on the sliding glass door to my left and the windows to the right. There is so much else going on in this room that direct reflections are really not an issue. The room is one big acoustic defuser.

It's obvious I'm not married and for the most part, the only listener. The other chair is for Leo the border collie and he is not particular. Another reason a center channel is not critical.

I love listening to music and watching movies, but not enough to spends tens of thousands of dollars on equipment and construction. Nothing here was purchased new and I did a lot of it DIY. After years of buying and selling and shucking a jiving, I don't think I have more than $6k invested the whole system.

So what started out as a 5.2 or 7.2 project, might end up as a 4.0 (or 6.0 if I decide to add the backs). The addition of the Altec 604Cs as surrounds has made a vast improvement, but knowing what I know now about surround sound processing, they are probably wasted for the purpose and better utilized elsewhere.