[Danny Richie]

UPS tracking says delivered on 11/21, got there earlier than expected.

I hooked your amp up in my system today and gave it a workout.

I cranked up bass heavy tracks that included some big procession hits from the Blue Man Group, some Chinese Drums, Evanescence Breath no More (live), No Doubt's Hella Good, Bo Stief Dream Machine's Heart, and several others.

I set the amp up on the transformer and set my other amp up on its end (mounted in a four sided box) to watch for the LED lights.

Both your amp and mine flickered the LED lights at the same time one heavy bass notes.

They were both driving triple servo subs. So the impedance was lower and had more current demand on the amp than just powering doubles.

SPL peaks in room were easily hitting 100+ db levels with ease. Woofers maintained great control and were super tight.

I also set the settings on the 14Hz extension, with low damping, and the rumble filter off.  That is where I normally keep mine. No issues at all.

These were easily keeping up with the NX-Tremes that measure 94.5db. Amps had to be turned up to a 3 o'clock setting to match the output levels of the NX-Treme. Your Spatial Audio M3 Sapphire's are rated at about 91db. So keeping up with them should be a piece of cake with headroom to spare.

I also asked Brian about the LED lights and got this response.

The two red LED on the power amp board indicates the power rail has temporarily switch to high voltage rail: one LED for each power rail. When it is off, it means the power rail stays at half voltage rail to save power. These two are debugging LEDs to make sure when there is no signal, the power rails should be at half voltage level and when high demanding signal comes in, they can switch to full high voltage so that it has the correct max output. Older class A/B based A370 amps do not use rail switching and therefore does not have these two lights. If I have to guess, I would say the amp will begin to switch to high voltage rail when the output is about half to a third of full max output which is about 6-9db.

I also noted that after about 30 minutes of hard play your amp wasn't even warm.

And man, Amy Lee's voice is mic'ed up hot in that song and really loud at the levels I was playing it. It felt like a concert in front of me, and the bass guitar had really good texture and power. I could feel the strings. It ripped.

So back to your issue. Again, check your wiring. Just as it did from the beginning, it still sounds like you may have the woofers wired improperly.

[dallaire1]

I am glad to hear all of this Danny. I have to be totally transparent with regard to bass levels. I am one to believe in the Fletcher Munson curves regarding the non linearity of human hearing, however I think I have lost some of my love for this phenomenon. I curranty have one sub as assumed, and can say, I still like a downward tilt or "house curve" as some call it, yet I'm beginning to think the sound is just more natural and "less masking" of the remains of the audible spectrum without the low end rise. Like E-bird had suggested "my ears will grow". I think he has a point here. I have noticed the bass is going to take some time to get really integrated, looking at all the data ! two are definitely better than one as far as room integration goes. Much smoother integrated response ! I'm glad to hear the amp is working properly. On a serious note, I will be building sound deadening amp boxes or DC knockout adapters as these amps need to be in a sound damped enclosure to kill the buzz of DC offset they absorb. After all its a plate amp, and is meant to be in a box. Brian has given me good advice as to what to purchase to alleviate the situation regarding transformer "hum/buzz"

[dallaire1]

I'm just a little confused? Brian clearly said these were clipping indicators??? Or is that what you just said in technical engineering terms?

[Danny Richie]

I'm just a little confused? Brian clearly said these were clipping indicators??? Or is that what you just said in technical engineering terms?

They do not indicate clipping.

This quote that I posted was directly form Brian:

"The two red LED on the power amp board indicates the power rail has temporarily switch to high voltage rail: one LED for each power rail. When it is off, it means the power rail stays at half voltage rail to save power. These two are debugging LEDs to make sure when there is no signal, the power rails should be at half voltage level and when high demanding signal comes in, they can switch to full high voltage so that it has the correct max output. Older class A/B based A370 amps do not use rail switching and therefore does not have these two lights. If I have to guess, I would say the amp will begin to switch to high voltage rail when the output is about half to a third of full max output which is about 6-9db."

[Hobbsmeerkat]

In my experience when the amps clip, or when the woofers are pushed past their excursion limits, the front-facing power LED turns off to prevent over-driving or damaging the woofers.

My subs use the smaller/older HX300 with dual 8" woofers in a U-Frame stand my speakers sit on, so they're limited in deep bass output compared to 12" woofers in an H-frame, especially in large/wide rooms, and on occasion when they get pushed too hard, the power light simply turns off, but that's pretty rare unless I'm pushing deep bass notes playing Pete Belasco's "Deeper."

[dallaire1]

Interesting, I will have to check for that to happen. Never seen the backside of the amp while listening as they are not in sight.

[77SunsetStrip]

It never made any sense for clipping indicators to be on the back of the amps.  Now we know that the amps are functioning properly. 

[SoCalWJS]

Just sounds like it's a weird wiring issue.

Bad connector? Poor soldering? Something that's  a PITA to diagnose. If you have the time, are you able to just completely  redo all of it?

[Tyson]

It's been a long time since I wired them but I seem to remember that the woofers had to be wired in parallel and the servo wiring was done in series. 

Or maybe I have it flipped.  But the main point is that the wiring is different, might want to check your wiring on that.

[dallaire1]

Yeah I have checked it several times, woofers in parallel servo in series. Danny just keeps saying it lol. They have been correct. I guess we just ignore the lights and enjoy.

[Early B.]

Yeah I have checked it several times, woofers in parallel servo in series. Danny just keeps saying it lol. They have been correct. I guess we just ignore the lights and enjoy.

No matter how many times you've checked your wiring, it could still be wrong (I speak from experience ). There's a simple solution -- allow others to check your wiring by shooting a short video and posting it here.

[77SunsetStrip]

Have you determined what source from the NAD should drive the Sub amps? 

When you get everything hooked up again, experiment with the phase control on the Sub amps.  If you are letting the main speakers play all the way down, make sure the Subs and mains are not fighting each other.  Took me a while to discover Subs amp phase at 180 made a big difference in SPL and detail.  Maybe that is due to Ripole Sub configuration? 

Don't get hung up on Harman or other "house" curves.  Adjust to your taste, but DSP should be used sparingly.  For a long time, I tried boosting various frequencies below 45 Hz.  After removing all boost, and notching out a 50 Hz peak the really low information appeared.  Good Luck.     

[NoahH]

Have you determined what source from the NAD should drive the Sub amps? 

When you get everything hooked up again, experiment with the phase control on the Sub amps.  If you are letting the main speakers play all the way down, make sure the Subs and mains are not fighting each other.  Took me a while to discover Subs amp phase at 180 made a big difference in SPL and detail.  Maybe that is due to Ripole Sub configuration? 

Don't get hung up on Harman or other "house" curves.  Adjust to your taste, but DSP should be used sparingly.  For a long time, I tried boosting various frequencies below 45 Hz.  After removing all boost, and notching out a 50 Hz peak the really low information appeared.  Good Luck.   

Your phase point is super good. That could easily be the issue. It is one of the reasons why everyone suggests only doing DSP at the very end and manually getting everything as good as possible without it, and only activating it at the end (if at all).

[EdwardT]

When other OB sub owners wire their servos, do they wire the rear facing servo out of phase like the speaker coil?

[corndog71]

There’s a thread all about this.

https://www.audiocircle.com/index.php?topic=149708.0

[wingsounds13]

When other OB sub owners wire their servos, do they wire the rear facing servo out of phase like the speaker coil?

Short answer, yes.  The voice coil and servo coil must be wired with the same phase relationship.

J.P.

[dallaire1]

It's quite a simple schematic to follow. Seriously, people only get hung up if they have the second woofer facing opposite direction. Drivers are still parallel, servo series.

[dallaire1]

I just have a few final comment's on this entire thread. I realize Danny, you are a salesman and have to say whatever you need to in order to keep sales up. I totally get it. These speakers are no different than any speaker EVER made ! these subs are no exception, they have compromise's and limitations. If it weren't for the servo portion of these amps, they would be NOTHING special. I can honestly say I have never heard as much noise from any design in my life regarding A/B amp design, but in Brian's defense they are made to be burred in a sealed dampened enclosure. These amps clip on high level bass peaks "period" with an OB design. You can say whatever you want about that. I have asked the owner/designer himself regarding these amps, they are clipping. Brian has his PhD in Electrical Engineering and has explained to me as I have posted pages ago, the problem is the OB design is taxing the amp clean out of any headroom it would have had in a sealed design, (this is a fact). At high levels due to the front/back wave cancelation effect (Physics) again. I can get 100Db also, but not low, without clipping. Sorry. I was going to spend all sorts of time filming and running tone burst and taking readings at different frequencies so you can all in fact SEE what the shortcomings are with this design, but I've decided we've all probably heard enough.

When can I get the amp back from you Danny ? I'm sure I have to pay of course. And I'll just say, keep up the good work Danny, you sold me ! And I like to think I make pretty good informed purchasing decisions. You have skirted, ignored and flat out disregarded any direct questions or concerns to save your limited performing product. Again they sound great, I will admit, just don't play them loud. If anyone needs me to repost the actual e-mail correspondence with Brian I can. I quoted him verbatim. As far as not have two woofers wired correctly, that is not the case. I would encourage anyone with the LED's to flip their own amps, play some load, low content and take in the light show !!! CLIPPING.

I have held this back for a long time. I received a call from one of your "supposed" friends and colleague warning me to be carful implementing these subs with the M3's. I would NEVER tell on an open forum, who that someone is, but I will say he sure knows what he's talking about. I obviously just disregarded his warning and here I have been.  Anyway, live and learn I guess. Your pride in your product is just a little over the top Danny. This coming from a man that basically makes a living tearing down other engineers that would probably lose there job if they couldn't hit a price point with a design. Must be nice to put everyone on blast with what a crappy job "they" have done. Check your own eye my friend, you may have something in it yourself.

Vince
 

[Tyson]

Here's one more thing to check.  If there's no wiring problem and no setup problem, and if the issue is you just listen very loud and the subs are reaching their limit, here's how to check that:

Run the subs to the point where you feel like the amps are clipping.  While the song is playing, go over to the subs and visually check out how far the drivers are moving back and forth.  If you are listening to music very loud and the subs are at their limit you will be able to see the woofers moving back and forth VERY FAR.  Like close to 2 inches back and forth. 

If that's happening, then maybe you just listen much louder than most people.  On the other hand, if you don't see the drivers flapping around like crazy, then there's a problem somewhere.  Probably with your NAD or with the wiring.

[NoahH]

Can I suggest we let this thread die? This has been a painful exercise for everyone who has tried to help. I know it is my own choice that I click into this topic periodically, but I suspect that if it he advice so far has not gotten anywhere in 15 pages of posts, it is not going to now.