# Reckhorn B2 Bass Management Device



## jagman

Hey guys. I've been interested in getting a simple bass management device for my IB sub that includes a SSF. Like most of you, I use a pro amp to power my subwoofer. Like many of you, I've often wondered if my amp was receiving a powerful enough signal from the sub out from my receiver to function at it's best. Reckhorn has a product called the B2 that could fill my needs. If interested, check out a PDF of the Users Manual. As you can see in the links, the B2 has a user adjustable 4th order SSF that can theoretically be set as low as 10Hz. It also has a user adjustable one octive parametric EQ filter that can boost the signal at the chosen frequency up to 12 dB. Lastly, it has gain control. Since most devices with gain control are unity gain (that is they only cut gain), I had hopes that this device would be different. 

So... I contacted Reckhorn regarding their B2 device via e-mail, and this was the exchange...



> I live in America and purchased the B2 Bass Management device yesterday through Bob Reimer at CSS in Canada. I have one question regarding it's gain conrol. Does the B2 have + and - gain control or is it just an attenuator?
> 
> The MAIN LEVEL is the gain control. At 12:00 o'clock = straight up the gain is about 0 dB: input = output signal. From 12:00 - 17:00 you can increase output signal up to 10 volts.





> I have an infinite baffle subwoofer and am looking forward to protecting the drivers from the really low frequencies... not to mention using the parametric boost at 20Hz. Having + and - gain control would be really nice since the subwoofer is powered by a pro amp but I'm using a consumer A/V receiver.
> 
> Yes, this exactly is the purpose of B-2. Many users buy it for the variable SUBSONIC only. Every subwoofer will sound better when you filter iddle / blind power = what your amp produces but your speaker cannnot deliver. Very important for bass reflex as well: below the port tuning frequency the response curves goes down sharply - but the amp is still pumping lower frequency power into the speaker voice coil which heats up resulting in thermal compresion (higher impedance of hot coils) and eventually burning. Many use it for smaller speakers like 3-5" full range. These speakers are good for one point source but the X-max. is short = very limited bass capability. If you set the SUBCSONIC just as high as you hear slightly less bass than this is the right setting where the speaker is limited and should be relaxed from those iddle power. This will also keep yur amp cooler or you have more reserve to have more power reserve for the audible range. Do not underestimate the variable / parametric BOOST LEVEL. You can extend bass about 1/2 octave. The trick is a well set combination with SUBSONIC. .


So... the B2 has:

1. A user adjustable SSF that can go as low as 10Hz
2. A user adjustable one band, one octive parametric EQ filter that can boost the signal up to 12dB
3. A gain adjustment knob that can decrease gain, but also increase it up to 10v

Sonnie has a B2 that he uses and has found that the SSF when set to 10Hz actually performs like it is set to 12Hz. That tells me this device has a lot of potential, but is not as accurate as it could be. To get around this, all one has to do is to run closed curcuit sweeps with REW to see what the various adjustments really do. Considering what we already do with REW when setting up our BFDs, that should be pretty simple. Then we modify our SSF and low frequency boost settings based on what WinISD recommends for our subwoofers given how many watts we send each drivers.

Based on my needs and what I've heard so far, I went ahead and ordered a B2 for my HT. It will take a while to get it set up (I recently moved), but I'll report back once my HT is properly installed. This device could work really well for sealed subs, IB subs, ported subs (LLT or otherwise) and large main speakers alike.


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## jagman

A couple notes...

1. Obviously 1 band of EQ is less than most people on this forum use... but I don't see why a BFD couldn't also be used in the chain. Since most of us already have a BFD, that shouldn't be an issue.

2. Many people use sophisticated automated room EQ systems (like Audyssey) for their HT. The main complaint I've heard is that these systems automatically go to a flat response over a relatively large area (multiple seats). If one wanted, he could get the B2 and set the gain and SSF appropriately for his sub amp and drivers. Then, while keeping the boost EQ at 0dB, run the auto EQ. Afterwards, he could set the one octive parametric EQ to 20Hz and dial in boost. Since the auto EQ is set to give a flat response to a large area, the one band parametric EQ house curve should in theory extend to a larger area than just the sweet spot. This way, one can safely drive his subwoofer, use modern auto EQs, yet not lose the ability to have a house curve. Of course this is theory, but I plan to test it out and see how things sound.


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## jagman

BTW, it costs $89US... $100 exactly with shipping to California. Bob at CSS in Canada (who has a subforum here at the Shack) is the only retailer in North America. Since he lives close to the US/Canada border, he crosses the border himself and then mails it which of course keeps costs for his Ameican customers down.


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## Sonnie

Thanks for the info jagman... good stuff.

A couple of notes... CSS is a sponsor of the Shack and as you mentioned, they do have a forum here... 

Creative Sound Solutions.










Following are the tests I performed with REW and the B2 looped...

Red = Sound Card
Blue = 10Hz HPF setting
Green = 10Hz HPF setting with 20Hz boost (12 o'clock)


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## jagman

Do you remember how much boost you had to put in at 20 to make the plot look like it has a 4th order HPF at 12 Hz? from the plot it looks to be about 3 or maybe 4dB.


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## Simonno10

I finally received the Reckhorn B-2 EQ and have a question and would appreciate suggestions. As I’m new with this I followed the instructions provided with the unit (not all that helpful) and set all the dials to 12 O’clock except the subsonic frequency, which I set to approx 13-14Hz. There’s no 100% way to know if I have set that dial between 13-14Hz other than going by the manual where it states where 7 O’clock (10Hz is fully to the left) and half way (quarter to) is 9 O’clock so with that in mind I set it between 7 O’clock and 8 O’clock (8 being 14Hz). Reason for setting to 13-14Hz is that's what SVS suggested I do as I own the B4+ Sub powered by an Ep-2500 amp with 2 ports blocked.


Also when using the Radio shack analogue spl meter do I:

1.Turn up the attenuator on the pro-amp (channel 1 only for bridge mode) 
2.Turn up the Boost Level (3rd dial from the left on the B-2) 


Do I touch the Boost Frequency dial at all on the B-2? It’s currently at the 12 O’clock position

Thanks in advance


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## Sonnie

I would probably set it very close to 7 o'clock. At 7 (10Hz HPF setting) it is actually running around 12Hz HPF.


Red = Sound Card
Blue = 10Hz HPF setting
Green = 10Hz HPF setting with 20Hz boost (12 o'clock)










If you want to get precise you can loop it through you sound card in and out and run REW sweeps until you get it set where you want it.


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## Simonno10

Ok thanks Sonnie. I received a reply from SVS (great people and patient) and have instructed me not to use the Boost Level on the B-2 (turn it counterclockwise) and just set the subsonic frequency to 13-14Hz for 2 ports plugged. Unfortunalty I had forgotten that they mentioned turning the Boost Level to 0 and performed an 8 position Audyssey calibration. Not sure if now I have to redo it.

Also must again mention a special thanks to Ed from SVS ,he has been awesome in tolerating my endless questions regarding the setup of my sub and the B-2 among other things. Would be lost without his help.

Thanks for the reply Sonnie


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## Sonnie

With no boost you can probably just set the HPF fully counter clockwise and be fine. The HPF will be a bit higher than 13-14Hz, but it should still be okay.


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## gperkins_1973

Sonnie,

Is it easy to set the reckhorn B2 to a 12hz hpf with a 4th order slope. That is why I need to do to mine when I get one. And do many people apply any boost to the low end with the hpf engaged. Just wondering out of curiosity.


cheers

Graham


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## Sonnie

I am not sure you will quite get there.... more like about 18-20Hz per octave from what I can tell, but you might tinker with the boost a little and make it.


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## Simonno10

Hi guys. Another thing I should mention is after taking out the s-convert and put in the B-2 I went back to using an XLR-RCA from pro-amp to B-2 (was using XLR-XLR b/w S-convert and amp) and ran Audyssey and it came up with sub out of phase? I've had this before but was fixed when I use XLR(male)-XLR(female) from S-convert to Ep-2500 amp. Not sure what's happening here as I rechecked the speaker connections from amp to sub and they are correct. Only thing that has changed is the B-2 and going back to using the XLR-RCA cable. I'm going to try a 1/4 TRS-RCA or get a new XLR-RCA cable today. I've had the XLR-RCA cable for years (over 10) and can't be sure it's wired correctly as it was made for me by a Hi-Fi shop I used to visit regulary.

*Update*

Purchased a Horsa 1/4 jack-RCA so will try that tonight and see if i still get the out of phase message after the Audyssey calibration


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