After extensive testing, listening, adjusting, experimenting, and even some harsh torture testing, I can now announce the new SubMersive HP+/F2+ amplifiers are available for order and in stock.  There are a few details to cover which I'll break up for easier reading:

The Home Theater Series Amplifier:
This new version of our SubMersive amplifier uses the same US made, very efficient (>90%), 4000W, class D amplifier section proprietary to our OEM SpeakerPower.  In 2010 we introduced the 2400W version of this amplifier in our SubMersive HP.  The new Home Theater Series retain the same 4000W amplifier which drives the SubMersive + unit and optional slave, but adds an entirely new input section, controls, and DSP to program manage it all.  Our amplifiers have used the same DSP optimization and input section since the SubMersive's introduction in 2006.  While very capable, it had limited flexibility with many features and capabilities we did't use in a home subwoofer application.  Over the years the price of the parts involved have also crept ever higher.  We have been working with SpeakerPower to help develop a new set of features and controls for quite a long time and have had multiple improvements made over the past 2 months after we were sent the "production version" of the new amplifiers.  

The result retains the strengths of our highly regarded SubMersive HP+ & F2+ while adding more controls, features, range of adjustments, and even a little maximum headroom.

Here is a look at the new amplifier:

Here is a closer look at the new input section and controls:
This picture is also the recommended starting point for using and XLR input and the 12V trigger (3.5mm mini-plug).

Here you can see the original + amplifier next to the new version loaded in a pair of SubMersive F2 cabinets:

Now on to what's new:

1.  Digitally programmable control knobs: While the 4 knobs on the amplifier above look like your typical controls, the audio signal never actually flows through the knobs.  The knobs function like a variable fed to the internal DSP.  This means every subwoofer designer can program the knobs to behave as they like, and the function of each knob can be changed with a few clicks of the mouse and re-programming the amplifier (factory programming only).  This provides DSP precision and functions that are very hard to implement in the analog domain.

2.  Wide range GAIN (volume) control: The flexible programming of the new amplifier allows up to 10dB greater gain for the rare 2 channel system that will need it, while we have added a much wider range of adjustment around and well below the bottom 2 notches on the old volume control.  Plenty using 2-4 SubMersives found themselves at the lowest volume settings on the original amplifier, where those users will now have much finer adjustments available.  Not only does the gain control now allow a wider range, but 3 o'clock and 12 o'clock on the dial correlate to the original amplifiers 0dB and -16dB settings respectively.  Coincidentally, -16dB was the range I recommended most to start calibration to insure they had enough gain.  There's no problem going lower, but 12 o'clock on the dial is the recommended starting point.

3.  LF EQ (low shelf/adjust extension/room size fitting):  The LF EQ knob translates the Program 1 & 2, 19Hz and 15Hz response curves to a dial where 12 o'clock is identical to our original program 1, 19Hz mode, but you now have a range of +/-8dB across 11 evenly spaced curves, where the original was a single shelf of ~ +3.5dB. This equates to an outdoor response adjustment of the +/-3dB range (6dB window) of 12-27Hz.  If you have flexible manual EQ in the system, you could implement most of what the program settings and LF EQ offers, but many don't or won't get quite the right shape of things where this makes it very easy to dial in whatever lift/house curve you are after.  This is especially useful for adjusting the LF character after running room correction such as Audyssey where you cannot easily edit the target curve.

4.  Low pass crossover 30-120Hz + 200Hz: The new amplifier adds a 4th order (24dB/octave) low pass filter. While I very much prefer for 2ch listeners to have some form of response correction in the system to get the best sound quality, this opens many more possibilities in 2ch systems where you can use devices such as DSPeaker's AntiMode products or MiniDSP's Dirac boxes which don't include a low pass. You can also use the internal low pass to get a workable blend with the speakers and then use a single, full-range correction system such as Dirac, Trinnov, or AntiMode Dual-Core. Having a low pass at the amplifier can sometimes makes for a useful added flexibility in a home theater setup when blending multiple units or taming some in-room peaks just above the operating range. If the delay adjustment didn't quite get rid of some localization of a rear subwoofer, or you're having trouble getting a good blend with only delay adjustment, sometimes a low pass can work on its own or in combo with less overall delay as the low pass filter has some inherent delay of its own that changes with frequency to give a little different blend and less upper frequency contribution.

5.  Delay adjustment 0-20ms: If you have a single powered unit being used with a modern surround processor, the delay adjustment isn't of much benefit.  For those with more than one powered subwoofer, the delay function will allow some to eliminate a device and A/D-D/A step in an external box like a MiniDSP or DSP-30. If you already have a room correction system like Audyssey XT32 or Dirac this is a significant advantage when using multiple powered units as most are much better equipped to correct the response of the subwoofers as a group after you adjusting placement and delay to get a good summation and starting point. Even though Audyssey XT32 does attempt to apply delay, it still EQ's the subs as a whole, and I have always found better results if the delay and blending is done manually and then letting Audyssey correct the whole.  To confidently set the delay value acoustic measurements really are required.  Accordingly we will now be stocking and selling the MiniDSP UMIK-1 which you can purchase from us and ship with your subwoofers.

6.  12V trigger and auto sensing: At long last the SubMersive has power control.  The auto-sensing circuitry works fairly well, but does require some level of signal to turn the amplifier on.  If at all possible I strongly recommend picking up a 3.5mm mini-cable to connect the SubMersive to the 12V trigger outputs found on the majority of modern receivers and preamplifiers.  The 12V triggered standby mode turns off the amplifier output stage and reduces power to 1/4-1/3rd of idle and eliminates any chance of line induced noise while the system is off.

7.  XLR & RCA inputsNo need for adapters! While those who know they will eventually have a preamp with XLR connections may still want to run an XLR cable and use adapters, the best practice will be connecting XLR-XLR & RCA-RCA. This gives the lowest probability of hum or buzz. These higher power models do need to utilize the 3rd pin safety ground, but addressing ground loop issues in an XLR-XLR, or RCA-RCA system is less problematic and often grounding the preamp solves the issue.  The small switch to the left of the RCA inputs changes grounding and the signal sensing circuitry for the respective connection.  The switch should point at the connectors being used (XLR or RCA).

8.  Summed RCA inputs:  While the new amplifier retains the very handy, looping male and female XLR connections which are internally Y-connected, the 2 RCA inputs are summed to allow a stereo signal or any 2 analog signals to be summed to mono.  This allows the HP+/F2+ and respective slave units to be used in a 2 channel system without the requirement of an external crossover or preamp with a mono subwoofer output.

9.  Proprietary overload protection:  Achieving the same level of non-offensive, yet nearly bullet-proof overload protection proved a significant task in the new amplifier. The new DSP is a drag-n-drop, open pallet of options with a huge library of tools. While SpeakerPower offers some starting point suggestions, each designer can make a near infinite number of changes, additions and combinations.  Defining the new overload behavior of the amplifier confirmed just how well the original design worked. The new DSP offers tools and configuration options with finer adjustment and the potential to make some improvements I've identified over 5 years of observation and experimentation.  After a lot of testing, tinkering and way too many hours listening, I'm happy with the result that allowed us to gain a little clean output before any protection kicks in while maintaining the very benign overload behavior that many never even notice protecting against the surprise, momentary burst in a movie or song that asks just a little too much.  While many owners never approach these limits in regular listening, most of those who seek out a product like the SubMersive will eventually explore those limits, and I expect a competently designed subwoofer to sail through such exploration.

10.  IEC Power Cord:  The blue PowerCon power inlet for the SubMersive has always been a love/hate relationship.  Most can appreciate the confidence in the twist-locking power cord that cannot fall out when scooting the subwoofer into a corner or against the wall.  At the same time, the PowerCon requires a full 2.5" of added depth and is not available in a right-angle connector.  XLR connectors and even the SpeakOn connectors to power the slave units are all available in right angle connectors.  The right angle IEC connector adds only 1" of depth leaving the right angle XLR or SpeakOn to set the minimum depth to the wall.  The PowerCon connector also makes custom or replacement power cords much harder to find and much more expensive than common, heavy duty power cords.  In order to provide the heavier duty, 10' or 2.5m long power cords we have long offered, we have to hand terminate every power cord which goes out the door.  With the move to the IEC standard power cords we are able to order and stock 10' long, heavy duty power cords for North America and the more than 28 countries we have shipped to which arrive ready-to-ship.

Pricing and availability:

By focusing on the specific tools suitable for a home audio subwoofer application and moving to more efficient devices we have been able to make all of the above improvements without raising the price of the SubMersive HP+ or F2+.  With the production of the SubMersive well studied here, we are in fact able to REDUCE the price of the SubMersive HP+/F2+ units by $300! [eek]  

SubMersive Packing:
Some might notice above that we now have the same shipping estimate for the HP & F2 models.  That is not a mistake!  The new amplifiers have knobs and switches which need more clearance in the packaging.  A simple modification of the F2 packing allows in-stock F2 models to ship right away.  We needed to redesign the SubMersive HP packing which is due to arrive by the time we get back from the Thanksgiving weekend (by December 1st).  This new packaging uses thick, polyethylene foam caps which are easier to unpack/repack, handle multiple shipments more safely, and sneaks under an oversize threshold with the shipping companies saving ~$40 per shipment.  By staying under this threshold we can now ship the SubMersive for a similar price as the F2 to most of the US, and we are able to ship the HP+ & HP-Slave untis as a package overseas with FedEx where we previously these could only ship internationally on a pallet.

I will be making many updates to the forum through the weekend and into next week, including details for those wanting to upgrade, and some great deals on earlier versions of our amplifiers which have been traded in.

For those ready to order, please e-mail us ( ) with your shipping address and we can confirm your delivered total, payment options, and lead times (we have plenty of black maple HP/F2 units).

More good things to come! [cool]

Mark Seaton
Seaton Sound, Inc.
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Pricing updated 8/01/2018:

For those who may want to upgrade to the new amplifiers we will offer a credit for the return of of 1 previous generation amplifier toward 1 new amplifier:

New HP+/F2+ amplifier = $1300

Less return of 1 amplifier:
4000W + amp = -$500
2400W HP/F2 amp = -$300
1000W original amp = No trade in value available.  All units in the field are now 6-13 years old.

This means upgrading from a 2400W model will be $1300+shipping with a credit of $300 when we receive your amplifier for a net cost to upgrade an HP/F2 model of $1000 + shipping.

If upgrading from an original 1000W model the net cost to upgrade an original 1000W amplifier model of $1300 + shipping.

Accordingly we will be selling the trade-in units loaded into brand new SubMersive enclosures for:
previous HP+/F2+ = $1795 / $1995 (2 year amplifier warranty)
SubMersive HP/F2 = $1595 / $1795 (1 year amplifier warranty)
SM HP-1k/F2-1k = $1395 / $1595 (1 year amplifier warranty)

All amplifiers are still easily serviced well past their warranty expiration.
 All prices above are +shipping.
Mark Seaton
Seaton Sound, Inc.
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The internet is more fun with pictures, so I'll add a few here we've recently taken.

While I know these photos will create many questions of "Do I have to stack the SubMersive HP+ & HP-Slave?" they make for a great visual, and we do have a few visible customers with units stacked just like this behind a screen wall or even out in the room (click images for full size slideshow):

[SM-HP-stack-08-1400]     [SM-HP-stack-05-web]    

[SM-HP-stack-10-web]     [SM-HP-stack-11-web]  

[SM-HP-stack-13-web]     [SM-HP-stack-12-web]  
Rosenut SubMersive HP:

[HP-RNut-2]  [HP-RNut-1]  

SubMersive F2:
[F2-blkM-wGrill-1]    [F2-blkM-2-800]  

[F2-blkM-wGrill-2-800]    [F2-blkM-3-800]
A peek inside at the bracing of the SubMersive F2 to keep it as rigid as the HP style cabinet:
Mark Seaton
Seaton Sound, Inc.
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Here are some quick measurements explaining what the LF Adjust knob does to the SubMersive's frequency response.  To be clear, this doesn't change the maximum capability at any frequency, but it can make it easier or harder to reach those limits if the knob is full boost vs full cut.  The purpose here isn't to make huge EQ adjustments, but to provide a better starting point in various size rooms and provide appropriate range of adjustment for owners to "season to taste" once levels are set and ideally room correction is run.

Here you can see the change in the frequency response as the knob is turned up (BOOST) or down (CUT) vs the native response.   This graph shows the response of the knob on a 5dB/division scale to give and overview (click on the image for full resolution):

Only the maximum boost/cut settings have much affect above 50-70Hz.  This type of control is perfect for adjusting the response to a larger or smaller room, as well as making adjustments AFTER running a room correction system like Audyssey which doesn't easily allow you to adjust the target curve.

Taking a closer look blown up to 2dB/division, we see a +/-6dB swing around 20Hz and close to +/-8dB at 10Hz.  The gradual contour at the intermediate settings make for very useful fine adjustment to achieve the balance you are after:

And finally we have a set of curves taken indoors and nearfield on a SubMersive F2+.  Being indoors we still have some minor bumps from the warehouse above 35Hz vs the super-smooth outdoor response, but the relative change is correct and the response generally representative of what happens as you turn the knob.  Of course on the new amplifier you no longer have to cycle the power to change the response curve. The changes happen in real time.  The 2nd curve on the boost(+) side matches the frequency response of Program 2 on the original amplifiers. (click image for full-resolution)
Here again you can see the cursors set to 60Hz where even at full boost/cut the change is only +/- 0.85dB from flat which is at 12 o'clock on the dial. (click image for full-resolution)
Mark Seaton
Seaton Sound, Inc.
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