[dallaire1]

Hello all,

Well, it’s been a long time coming and still not quite done yet, still have to make grills, it's always the grills that get made "whenever"... Not exactly the easiest build I've ever encountered but not too bad. I have about 100-man hrs. In as I'm writing this and still need grills and clear coat lacquer tomorrow.

I have gotten to spend some time with them for a couple weeks fully functional but not cosmetically finished. I must say, OB bass is completely different than anything I've heard at this low a frequency. The best way "I" can explain it, is that it sounds like "headphone bass", no BOOM or hangover effects. Very quick and tight. I ran quite a few measurements using REW and played with things for a good 5- or 6-hours getting things dialed in to my liking. I played with the Sub settings quite a bit. They will get LOW! but struggle a bit with reaching full excursion with "bass torture" tracks. I ended up using the 28Hz, High control setting. To me it’s a no brainer...you get as low as you ever really need to for most music, and the setting just sounds much quicker and taunt to my ears. In retrospect, knowing what I know now, I probably would have gone with the triple stack for the simple fact of limiting cone excursion as a unit. The amp only sees a "load" anyway so it wouldn't have taxed it any differently. Overall, I do love the sound for sure! I was always a bit of a "bass head" growing up in audio as a teen so I guess I was expecting a bit more "slam" out of them, but in all fairness, I know they sound very musical and "correct".

In life everything seems to be a compromise of some kind or another, like having tv console between the speakers for me. I was able to utilize the console as a left and right amp enclosure. The Speakon connectors come out the bottom of the console. I still have to build a pegboard shield around the plate amps on the interior side of the console enclosures to protect the electronics and such.

I was blessed with an audiophile wife, so it made the whole experience a lot more fun. We typically listen almost every night together, I love it. The Spatial,s are probably my last speaker, they literally still blow me away after a couple years with them! Although, I would like at some point to heard that AMT tweeter I hear so much about. I’m sure it edges out the M100 a bit.
I can now start treating my room finally. I also have another space that is larger and have kicked around moving the system and taking some measurements to see what I can get out of the room vs. the one I’m in. I am just able to get the M3’s (3) feet off front wall which to me sounds nice and smooth. I’m pretty much in the “mid field” with them and think they image like amazingly! Although still pretty much an equilateral triangle. I do have 2 inch, Owens 706 panels in place 5 feet behind my listening position which helps for now.

So, I guess this turned into a GR/Spatial review. I have to say I used DiracLive3 to phase align and correct for my untreated room. Curtain set at the Schroeder frequency area, about 200hz. Crossover point is set by Dirac itself so I will have to disconnect mains and subs independently to see what frequency was chosen. I have to say I am a firm believer in Dirac in this area! You cannot distinguish a difference in location as to where the subs are in relation to the mains. The low end is one cohesive, in step balanced sound for sure as soon as I defeat Dirac the phase change is immediately heard. I know everyone will say I don’t know how to set them up correctly lol.

I will post a couple pics of the build.

Thanks guy’s

[Mikethehunterguy]

I love the adapted credenza! Fantastic work! I am building the Triples now, and the NXtremes as soon as they can ship them out. I figure a couple months to get the flat packs finished and painted. I think I will have a local body shop paint them for me, but....I like to do it all when possible.

[corndog71]

That is a neat idea but you may be losing some performance by having the amps so far away from the subs.  The wiring between them ideally should be as short as possible and really no more than 3 feet. 

[mkane]

Guess I'm losing out. Ours are more than 30 in some cases. Which is the worst-case scenario. Long speaker wires or long interconnects?

[corndog71]

It has more to do with the servo connection.  The longer the connection the less effective the servo functions.

[Danny Richie]

I remembered you emailing me about the woofers reaching exertion limits and it really sounded like you might have had them wired wrong. I even recommended you check the wiring again.

Now that you have posted this I can see what the problem is.

Your servo amps are way too far away from the woofers. The servo system is trying to make corrections for woofer movements that already took place. In short, you are causing a delay in the control.

This is why we recommend that you add no additional wire lengths than what is on the amplifier from the factory.

Move the amps to right behind the woofers and shorten up the cable as short as you can make them and you should gain back a lot of control and it should minimize woofer movement and increase control.

On a good note, you have yet to hear what they can really do.

[jtwrace]

I was blessed with an audiophile wife,

Does she have a sister?   

[mick wolfe]

Before throwing out the baby with the bathwater, why not at least try locating the subs on the inside of the M3's next to the credenza. That would certainly seem to satisfy the wire length issue plus keep that neat built-in sub amp feature intact. Just a thought, don't shoot the messenger.

[Early B.]

Before throwing out the baby with the bathwater, why not at least try locating the subs on the inside of the M3's next to the credenza. That would certainly seem to satisfy the wire length issue plus keep that neat built-in sub amp feature intact.

That's a good idea. This would allow the OP to trim a few feet of wire from each sub.

And here's a wild thought for a future project -- turn that credenza into a triple OB servo sub!

[dallaire1]

Thanks for the ideas guys. I am going to try that when I get some time. I am a little discouraged though I must admit. If this information would have jumped off the page at me at the time of purchase I would have gone a totally different direction on the subs. I spent a couple hours on Rythmik's site and cannot find anything regarding this ? I must admit I didn't "open" and read "every" DIY issue there was on their website, but there is no "specific" line item that mentions cable length that I could find. I couldn't find it at GR Research as well ? unless I'm missing something... I thought I read everything I could find before making this decision. Sorry Danny, I love and respect what you do for us all and never miss a video, but must say I'm a little discouraged... I really didn't want amp boxes on my floor with more wires.

I'm a little perplexed as to "why" this is a problem ? both wires are the same exact length feeding the subs, both 12ga. OFC and electricity travels at 90 percent the speed of light ! Perhaps it's a micro resistance thing with additional cable length ?   I just find it hard to wrap my head around. but hey, if that IS the case then I obviously missed something.

Funny thing is, they sound amazing! and all dialed in  The bottoming of the woofer I was referring to was on a bass torture track like I had said "Black Lotus" by Walton. The track has unusually low bass in it that is sustained at times in the track, after selecting the 28hz, High control setting, the problem was resolved. Not to say I couldn't leave them at a deeper setting and get by. I am starting to agree a little with S. Linkwitz regarding open baffle bass and SPL levels not being able to expect much with OB below a certain frequency of around 38hz give or take, regarding cone excursion. Although he wasn't speaking of Servo Control systems either, so I will be hooking them up at some point to the direct amp leads and do some A/B comparisons with REW measurements and play the same track as before at the same level, with the old amp settings of "20hz, mid control" and see if they reach full x-max or not ? If they don't, It will be interesting and make a true believer out of me, and stand corrected.

Vince

[dallaire1]

This is all I can find at  GR Research regarding amp placement for my two DIY kits.

"
The amplifier can be mounted separately and connected via a Neutrik 4 pole cable connector. These are also available. If you need floor spikes they can be added as well."

[Hobbsmeerkat]

It's not really mentioned in the paperwork but the reason the amps need to be so close to the woofers is due to how the servo controls work.
It's not an issue with most of Rythmik's subwoofers is because the cable runs in their own designs are usually really short. (Within 1-2 feet in total)

There is a smaller, servo voice coil on the woofer. As that smaller coil passes through the magnetic field of the motor structure, it creates a very small electric charge that gets sent to the amplifier where it is used to tell the amplifier the position/speed of the woofer.
As the lengths between them get longer, there is a larger delay, as well as a loss of servo coil signal strength in what the servo controls see as there is higher resistance, though slight, giving the subs servo units incorrect information to where the woofers actually are, compared to where the woofers should be and the more likely it is to bottom out.

The easiest way to alleviate the issue would be to swap the positions of the servos subs and the Sapphires, and cut the wires shorter.

[Early B.]

I am a little discouraged though I must admit.

Think about it this way: there's a greater benefit to moving those subs closer other than the shorter wire length -- you'll likely get better sound across the spectrum. I'll bet your imaging locks in, midrange is meatier, and bass is tighter.

[dallaire1]

Yes I will definitely getting them on the inside and see if it makes a difference. Funny thing is I sitting hear listening pretty dam loud and they sound great. I can't imagine them getting better but I will still see for sure. Again, the only surprise was that one track bottoming. other than that I thinks they totally holographic as low bass could be.

I will post results and pics of response and performance difference if I can perceive one. Thing is they will be in a totally different location so it will greatly effect frequency response.

Thanks everyone

[wingsounds13]

The bass won't get any louder per se but it should be cleaner and tighter with the shorter wires.  You may gain a bit of headroom on the problem track with the tighter control but I wouldn't count on a big change there. 

J.P.

[Danny Richie]

I will see if we can update the site with information about keeping the amps close to the woofers.

FYI, I took peak bass measurements in our old listening room that was 26 feet long, 17 feet wide, had 9 foot ceilings and a large opening to a dinning room in the back corner. I was measuring a pair of dual subs just like yours. They were hitting 115db peaks at 25Hz. They were not being over driven either. That's a lot of output.

Oh, and I was measuring them from 15 feet away.

[dallaire1]

That's encouraging to hear, I will definitely get the subs on the inside of my setup with a direct connection in a couple weeks and listen to the difference.  It wouldn't be the end of the world if I had to scrap the console amp setup and build a couple amp boxes. Just really like the clean simple look. I will report back when I can come up for air with work and all.

Thanks Danny !

[dallaire1]

Well that was a fast two weeks! I thought I would get this topic resolved today. I removed the 10ft. cable from the left sub only and replaced it with a 18inch cable. The sub on the left was moved to the inside of the mains. Upon playing the same control track "Black Lotus" by Walton, the sub performs NO different than the right. On bass peaks with this track the woofers will bottom out at about 70% volume on my NAD M33 Integrated amp with stereo sub outputs. The amp goes into overload and begins to clip noticeably as well, (see pics) red led's lit hard. The volume setting on the sub amps are 3 clicks past center only.

Don't get me wrong here, the subs sound fantastic on anything with bass if you keep the amp setting to (28hz high control setting) I can push most any song to within 90% of the NAD without a problem before the sub amps start to clip. I am just going to reiterate that I must side with the late S. Linkwitz regarding OB bass, you simply cant get high SPL levels with open baffle bass to frequencies that are in the 20's not to mention the teens ! without an array of subs to limit excursion with an amp that has a lot more reserve. Again I think the triple stacks would have been a better choice with the higher power class D amps. Just my two cents.

The laws of physics I'm afraid still prevail.

Regards,
Vince

[Early B.]

Well that was a fast two weeks! I thought I would get this topic resolved today. I removed the 10ft. cable from the left sub only and replaced it with a 18inch cable. The sub on the left was moved to the inside of the mains. Upon playing the same control track "Black Lotus" by Walton, the sub performs NO different than the right. On bass peaks with this track the woofers will bottom out at about 70% volume on my NAD M33 Integrated amp with stereo sub outputs. The amp goes into overload and begins to clip noticeably as well, (see pics) red led's lit hard. The volume setting on the sub amps are 3 clicks past center only.

Don't get me wrong here, the subs sound fantastic on anything with bass if you keep the amp setting to (28hz high control setting) I can push most any song to within 90% of the NAD without a problem before the sub amps start to clip. I am just going to reiterate that I must side with the late S. Linkwitz regarding OB bass, you simply cant get high SPL levels with open baffle bass to frequencies that are in the 20's not to mention the teens ! without an array of subs to limit excursion with an amp that has a lot more reserve. Again I think the triple stacks would have been a better choice with the higher power class D amps. Just my two cents.

Don't jump to false conclusions! There's a bunch of people on this forum with the same sub setup that don't have the problem you're experiencing. A shorter cable isn't gonna fix that issue (although you still need shorter cables).

I'm willing to bet that your settings aren't optimized. Unfortunately, there's no manual or online instructions to guide you through the setup process, and it's not intuitive. It's up to you to experiment. If you ask me how I know, it's because I've been where you're at - exactly the same scenario, and I fixed it with the settings. FWIW -- my rumble filter setting is on 14Hz and the extension filter is set to 20Hz. I'm hoping others will chime in to offer advice on A370 amp settings.

Be patient -- you'll eventually stumble upon the right configuration.  In the meantime, enjoy the other 99.856% of your music.

[dallaire1]

I most certainly will