Implementing a third sub...new Funk Audio Rack amp pics...

So as some of you know, I built a couple dual opposed AV15H subwoofers a few years back (two ~115L boxes with 2 AV15H drivers in each with a QSC RMX-5050 amp driving it and a DCX2496). I had incorporated a PB13 in sealed tune into the mix as I didn't want to get rid of it. Fast forward a couple years later, and I recently won an SVS SB13 Ultra sealed sub (1000 watt DSP amp, ~18" cubed).

I also recently picked up an Intergra DHC80.3 which has Audyssey XT32 and SubEQ, and I also purchased a rack style 2 x 2400 watt x 4ohm amp from Funk Audio to replace my noisy QSC RMX-5050 (even modded the fan noise drove me insane). The amp uses Alldsp.com software for EQ, and is somewhat similar to MiniDSP software in functionality.











I setup my 2 AV15H subs on the Sub 1 and Sub 2 preouts on the 80.3, and calibrated them both in "2 CH" (i.e., had Audyssey calibrate each signal independently). I came up with this after playing around with the distance controls and crossing my Paradigm S2 bookshelves at 120Hz..



I've been trying to incorporate the SB13-Ultra (which is placed nearfield at the back of the room, vs the 2 AV15H subs which are located at the front flanking the Plasma and acting as "stands" for the S2's). Basically I'm using one of the RCA preouts for Sub 2 on the 80.3 (which already has Audyssey applied to it) and trying to see if I can use the DSP controls on the SVS sub (LPF, phase, room compensation, etc) to keep the FR as flat as possible.

But so far no luck. Any hints as to how I can incorporate this puppy in the best way possible to gain some headroom while improving or at worst not hurting the FR?

Given the response I'm getting, is this just a fruitless exercise? Figured I'd add it in to gain as much headroom as possible. Even though I don't really need it in a ~1800 cubic foot family room.

Oh yeah, here is the response I used to get with the PB13 mode incorporated into the system in sealed mode (very similar DSP controlled amp) with my old Marantz AV7005 (green line). Unfortunately I can't recall what the settings were that I had used.

Not yet. I was considering using a XLR Y Cable to hook up the front 2 DIY's as "1" subwoofer, then using the second channel for the SVS SB13. I was wondering, however, if that would end up causing issues with the SB13 possibly being the "weakest" link in the chain?

One thing I hate about Audyssey Equipped processors, is that none of them allow you to save 1 or 2 sessions. I.e., I can't just revert back to the previous Audyssey session and have to rerun it. I think, anyhow!

Tried using the Y-Cable to treat the front subs as one, and the SVS sub was on the 2nd channel and reran Aud XT32. It just made things much worse, and cut off the response at 15Hz. So went back to the way it was before (and of course don't have as good a response as I did the first time around!).

I wish I recall the settings I had on my PB13 in sealed mode back when I used it to fill in the FR. Everything I do now just seems to cause cancellation issues in the FR. Hmmm... may be more trouble than it's worth.

Started to do that, but as soon as I inserted the 3rd nearfield sub into the mix everything went wonky and there seemed to be cancellations all over the place. My try again at some future date. I'm sick of the 20-25 minutes it takes every time I have to rerun Audyssey because I can't save some presets.

It's a wonder someone hasn't thought of allowing the saving of at least the previous Audyssey calibration, though maybe you can do it with the "Pro" calibration version.

BTW, for the next session where I get some free time to run REW, what is the best way to dial in 3 subs (positions are what they are and can't be moved)? Dial each one as flat as possible individually and then together to see where the cancellations occur before running Aud XT32?

Price was ~$1700, so certainly not inexpensive and likely won't be a huge product for the DIY crowd (isn't meant to compete with the iNukes of the world for instance). I'm not even sure Nathan is going to offer it to people who have not ordered his subs. We were exchanging emails back early last year if I recall and he mentioned he was thinking of building some of these if I was interested. He finally started ordering the parts/supplies back in April/May if I recall, so it was a long time waiting.

Yeah, the logo is sweet, basically just etched into the aluminum face with no colours.

You can download the software at the alldsp.com website and look at a "demo" mode for the 1800B to see the kinds of adjustments it has. Well, the UI anyhow. Unfortunately it won't let you select anything without a password for some reason, even in Demo mode. The password Nathan gave me seems specific to the unit I have. I'll upload some more pics of the interface when I get a chance.

Here are some pics of the UI. Like most software, adjust-ability is down to 20Hz only, even though the graph would imply 10Hz..

Here's what I was hoping to achieve going with the Funk Amp:

1. Eliminate the fan noise
2. Put a nicer looking component on the rack vs the QSC (stupid reason for some, but it is my family room!)
3. Gain some space on the rack by eliminating the QSC 5050 and DCX 2496 combo

All 3 were achieved, and I've sold the QSC and DCX so I'm happy. As for SQ, impossible for me to say I prefer the sound of one over the other. Pretty much the same in my opinion, except the noise floor (due to the fan noise) is heads and tails better on the Funk amp, so in fact from that perspective, the SQ is considerably better.

As for the Integra vs Marantz, honestly can't say I notice much if any difference in SQ. Aud XT32 compared to Aud MultiXT hasn't made any noticeable improvement in my room, which is why I had originally upgraded (numerous posts by individuals commenting on a "huge" improvement when they went to XT32, so I was curious). I didn't listen to music enough on the Marantz to say whether the Integra is an upgrade, but I am looking forward to being able to have Audyssey applied to 2.1 Channel stereo listening, which IIRC the Integra does while the Marantz doesn't.

The Marantz was a much cleaner/nicer looking face plate IMO. It was also a much cooler running unit, though as I understand it the Integra uses 140Watts vs 60 for the 7005, so this is understandable.

Will have to try that at some point.

I didn't think the price was that bad. But I believe some members scoffed at the idea when comparing to the pro-amps available at less than half the cost, etc. etc. It's less than 2 of these for instance ... http://www.minidsp.com/onlinestore?page=shop.browse&category_id=17, and I don't have to affix it to the sub.

Agreed, no safety cert which bugs me a bit. No 12V trigger, or for that matter, even a Power on/off switch. You basically have to plug both power cords in at the same time and leave on all the time. They have auto on/standby circuitry. Nathan mentioned for the next version he is going to go with 1 power cord vs 2 and a dedicated power on/off switch.

What are you crossing your mains at? I typically cross mine around 120-150Hz, so am concerned that with a nearfield sub crossed that high I'll experience a lot of localization.

No a return customer, but I was technically the first and paid him a while back (I think literally in April or May?). He did mention a couple months ago that the costs were coming in much higher than he originally anticipated.

Good point. Actually, I think that is what I used to do, set the PB13's internal setting to 80Hz. Too much food and alcohol these days, clearly getting to my brain.

It is placed nearfield, it's just "off" because I haven't been able to EQ it to a point where it's satisfactory. Doesn't seem to matter what I do, adding the 3rd sub in nearfield seems to create or enhance nulls.

Here's the best I've managed to get it after adjusting the polarity on the SB13 to 180 degrees from 0.



Next move may be to again try to combine the front two subs into one channel on the 80.3 and the SB13 on it's own channel, then use the AllDSP software to adjust the distance between the front two subs (I find setting one sub about 3 feet farther than the other front sub seems to help).

Didn't think adding a third different sub/location into the mix would be such a pain in the arse. For some reason it was easy the first time around!

Yes and yes. But I haven't tried playing with the SB13 on it's own dedicated line, so even though it's nearfield it's on one of the two preouts used for the front two subwoofers which are set at 21 feet and 24 feet respectively (I can't recall which the SVS is on). 180 degrees ended up being the best phase setting for the SVS. But I'm betting that if I put it on it's own dedicated preout with a shorter distance (and say set the front two at 21 feet then adjust for another 3 feet with the Funk amp on out of the DIY's) it will end up better. Unfortunately with young kids in the house all the time I rarely get the chance to play around for more than 30 minutes to an hour.