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Message started by 4krow on 11/28/17 at 22:37:00

Title: BSC= Baffle Step Correction
Post by 4krow on 11/28/17 at 22:37:00

Just to clarify, this is a temporary sort of solution that I am using, and it has to do with the break in of the FRX drivers, and some other devices. Thing is, there is much brightness in the midrange, and it is just the sort of thing that I don't care for while listening. At first, the FRX2 drivers were so remarkable that it was unbelievable. As time went on they got brighter and brighter. Sucked so much that I started preferring headphones to them in a big way. So then I discovered a line level 'fix' to accommodate for this sort of thing.... at least in this case. So I found a circuit designed by 'BottleHead' company that was used for Baffle Step Correction. This is usually done in the crossover of a multi-driver design, but in the case of single driver speakers, it makes way more sense to get it done at the line level in order to keep the clarity of the driver to begin with. Their answer for this is to attenuate the midrange, leaving the bass/treble sounding louder in relationship. Their is a selectable position for 5K, 10K, or 20K for the treble region, and 'narrow', 'normal' and 'wide' selections for the baffle width.They actually are 3 different turnover frequencies for the bass. Both the bass and treble can be adjusted by 2 or 4db or off.
Insertion loss for the circuit is 4db. Bottom line, it works very well, and will be incorporated in the system until further notice.
I am sure that those of you that own FRX2 drivers are asking why I don't just use the switch on the back of the driver that affects the midrange to begin with. Simple answer, it isn't affecting the midrange enough for what I want to hear. The 'Fixx' circuit sounds clearer to me, and so I consider it to be the answer.

Title: Re: BSC= Baffle Step Correction
Post by 4krow on 07/14/18 at 18:52:14

I ran into a Leeds & Northrup 'decade box' used for field use, that totally filled the bill for an enclosure of the BSC circuit that I have been describing here. Though it may be temporary, I couldn't resist buying this old unit, and began re-purposing it for this intention. I won't let it go without saying that the L&N product is of a quality that we just don't see anymore, regardless of price. I will have shots of the internal circuit ready at a later date. Unfortunately, I did not photograph the original components that made up the original circuit. It was truly a humbling sight, to see such workmanship, care and design all put together so eloquently. I only hope to build something that is in the ballpark of this philosophy. More photos as time goes on. FWIW, I am using as many original parts as possible, having the unit make sense probably only to it's maker. There are 4 controls for example that will have new meaning, and I will not attempt to re-label any of them. There will now be 'baffle size', bass level (2db,4db); then 'treble freq @ 5,10, or 20k' and treble level (2db,4db).

Title: Re: BSC= Baffle Step Correction
Post by 4krow on 07/16/18 at 20:54:26

This is the first step of the rebuilding process. I simply flipped the top plate upside down and reattached it so that working on the circuitry would be the easiest. Next will be the attachment of solder lugs to accept various components.


Title: Re: BSC= Baffle Step Correction
Post by 4krow on 07/17/18 at 19:11:18

This step was no easier than the last! Damned shaky hands and small parts. Next will be the addition of the needed caps and resistors.

Title: Re: BSC= Baffle Step Correction
Post by 4krow on 07/19/18 at 01:51:49

Suffice it to say that I have completed this project, and am happy with the results. I installed it first into my shop system where it made me want to build another just to use there.
Then I installed it with my Decware ZOB, and Racheal amp to have some adjustment there. What might seem a compromise to some is a blessing to another. I still had just a touch of the shout left in the FRX2 driver after 100 hours of break in, so this was the intention all along for this BSC/treble circuit to be used. 'A treble circuit to correct a midrange problem?' In this case, yes,,, let me explain. First of all, my room would benefit from the BSC part of the circuit by the fact that bass is a bit shy in my listening room. The circuit compensates for about 4db of that and is subtly noticeable. This is accomplished by the Lowering of the Midrange band above say 120hz (not sure of that number), where as the bass will sound louder relative to the midrange. To get the original volume back, you must raise the volume setting 4db to compensate.
Now, the treble part of the circuit acts the same way, but at the other end of the spectrum. I set to 5khz which lowers the amplitude of the frequencies Below 5khz by 4db. For me, the end result is that the midrange is affected again by being lowered, and the treble sounds louder in comparison. What this means to my ears that the midrange that sounds honky to me has been tuned down enough that I can enjoy the music, not waiting for the next honky note to show up, making me cringe.
Yamaha has used this same concept in their 'Natural Sound' series of integrated amps, where the midrange cut is variable, resulting in a different kind of 'loudness control'. Brilliant.
When/if I feel that the FRX2 drivers are fully broken in to my complete liking, then it will be time to remove this filter.

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