B&W Variable High Pass Alignment Filter Setting.

Thanks guys for your responses. The owners manual for the 808 in the discussion of Environmental Controls says, in part, the following:" However, some attenuation of the bass extension may be desirable, and an electronic bass control unit is in the process of development." To what does that refer?

Older thread but I just picked up a filter for my 801 matrix S3 - it improved things substantially. I did not use the preamp tape loop for connection but put in between the amp and preamp.

Greater solidity, more definition in the lows. Much nore enjoyable. The part I really cant get over though is that any woofer movement on LPS has now almost diasappeared to the point I don't need to use the preamp filter setting.

I am sure there are many enjoying this high pass bass filter and we usually only hear more about bad experiences "like everything else" - this kept me also from trying it out. If you have any matrix 800 series speakers recommend giving it a try hooked up between amp and preamp. They do come up on ebay.

Thanks Ct0517, very interesting. I have a pair of 801 Matrix S3 speakers. I have had them for 5 or 6 years, but only just heard amount the filter. The doc I read said it was for all Matrix 800 type speakers but went on to say it benefited the series 1 and 2, but did not mention the series 3 at all. However it did say that later 800 series speakers were designed not to use the filter as it was ahead of its time and confused listeners.

I'm glad you had a positive experience with my series of speaker. This has made me decide to try and get one, or make one. It is only a butterworth filter, with a tuned rolloff for the 801.

The doc I red is below:
http://kenrockwell.com/audio/b-w/800-series-bass-alignment-filter.htm

Thanks again.

Hi Fearn48

When the article discusses later 800 series it refers to Nautilus and onward. All 800 matrix series were designed by John Bowers to use the filter (equalizer). Here is the wording from the Rockwell article that hit home with me years ago. I have no affiliation with Rockwell.

(Actual article wording)

Genius top
Low-frequency loudspeaker design is usually at mercy of your box volume.
Box volume ultimately determines the limits of overall sensitivity and bass extension.
For any give box volume, the sensitivity and bass cutoff frequency are interrelated. To get more bass extension, you have to lose sensitivity throughout the entire audio band, or to get more sensitivity, you have to give up bass extension,
— unless —
you use a dedicated active equalizer designed to correct exactly the low frequency response, in which case, you can get the equivalent of a much larger box' improved low-end response, or more sensitivity, or a combination of both.
This little equalizer is the brilliant little addition designed as part of this series of speakers to allow much deeper bass and more sensitivity than one could get otherwise.

Later Years
The concept of combined electrical/mechanical loudspeaker design and equalization is beyond most people's comprehension, so B&W eventually went back to designing dumber speakers that don't take advantage of this filter.
As I recall, the Nautilus did away with this filter. That means that the Nautilus series is designed with a slightly more boomy bass that won't extend as deeply as the earlier speakers that are designed expressly for use with this EQ.
In other words, the original Matrix speakers are designed for a Bessel (underdamped) response, meaning there isn't a bump (resonance) in the bass response typically around 100 Hz.

When B&W went more mass-market after the mid-1990s, they retired this brilliant concept, as it was beyond the comprehension of everyone that didn't have at least a bachelor's degree in engineering.

Later speakers, like the Nautilus, are less damped, meaning that there is more of a peak in the bass response to try to eke out as much midbass as possible without the benefit of the intelligent optimization of this equalizer.

Now IMO – after 19 years ownership of the s3, my hearing supports Rockwell when he says this.

This little equalizer is the brilliant little addition designed as part of this series of speakers to allow much deeper bass and more sensitivity than one could get otherwise.

B&W support also confirmed to me that the sensitivity of the 801 increases with the filter. How the figure differs from the stock 87db is not published. (i.e. Is it 88,89,90db ?)

I can tell you that my 801's are far easier to drive than my Acoustat speakers and the Eminent Technology LFT8a's. My OTL's were designed to drive Acoustats with ease.

I have no intention of removing the filter and in fact my gear placement layout is based on the cables allowing for its use.

If you go to this site and download the 801 Matrix 3 series manual.

http://bwgroupsupport.com/manuals/bw-archive#ID_Matrix800Series
Within the 801 matrix S3 manual are the B&W specs.

801 matrix s3 without the filter (equalizer) are 39hz -20khz.
801 matrix s3 with the filter(equalizer) are 20hz – 20khz.

Here is the actual response graph from B&W.

http://cgim.audiogon.com/i/vs/s/f/1369683462.jpg

I am currently using The Maughanbox version of the B&W filter and still own the b&w filter. In talking with the engineer that designed the Maughanbox; it is essentially the same as the B&W one however it is made with better parts and also includes rca and xlr connections. Its also designed in a way that permits RCA inputs from the preamp and xlr outputs to your amps – if you are using a preamp with rca outs and need a longer run and are concerned about noise.

The Maughanbox version can be placed between the preamp and the amps. Its difference is it provides a (7dB boost at 20Hz vs the specified 6dB boost at 24Hz of the b&w one). It is very interesting when you first hear the sonic differences having been used to the b&w one for a few years.

imo - How all these components work good or bad – is dependent on our own rooms. Even more so here because these filters are changing the bass compression in our rooms.

Everyone's room is different so we therefore need to try it for ourselves and not put trust in other peoples reviews.

Trust your ears.

Cheers