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Discussion Starter #1 (Edited)
I'd like to share some info about an exciting SSF project I have been working on for many months. I now have some prototype hardware.

In summary it will be an adjustable SSF filter with 0.1Hz resolution, different gain settings, and preset filter types.


As seen in the photo above, it has a 3 digit LCD, AC power supply, RCA input, and a 1/4" phono balanced output.

A microcontroller controls the LCD, frequency, and filter type on the analog board. I haven't written the microcontroller
code yet, but I have assembled and am testing the analog board shown below.


There are 8 selectable gain settings from 0dB to 13dB (plus an additional 6dB for a balanced output).
The following graph shows the response of the input stage before the HPF.


The filter frequency is controlled by a clock signal generated by the microcontroller. In this testing I used an external signal.
The following graph shows the consistency of the response as the frequency is varied.


The last graph shows the frequency response in the following modes: 2nd order butterworth, and 2nd order peaking filters with
peaking of 3.0dB, 2.25dB, 1.5dB, and 0.7dB (Q=1.3066, 1.172, 1.044, 0.904).
There will also be a 4th order butterworth mode. I found that the SSF frequency was very accurate.



Please hold off on the extensive questioning - let me save my precious free time for working on the project.
Don't hold off on the encouragement though :)
 

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Your on to something here SturmMD, Looking forward to the finished product:T
 

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Looks primising. I'm sure you already know this but you have a couple competitors priced just under a $100. I really like the accuracy of your filters and the adjustable output gain (especially WRT using this with prosound amps). Keep up the good work!
 

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Looks primising. I'm sure you already know this but you have a couple competitors priced just under a $100. I really like the accuracy of your filters and the adjustable output gain (especially WRT using this with prosound amps). Keep up the good work!
Yeah, but 'they' don't have the easy and accurate dial-in freq-- 'they' are more like a guess of the freq. ED told me to get my voltmeter out and play test tones through their device while checking output voltage...c'mon! As if I'm going to do that each time I change my input device, or better yet, maybe I should scribble the actual numerical freq's on the faceplate:rant:
 

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Hmm. I have tried contacting Bob @ CSS a couple times with questions about the Reckhorn B2 but I keep getting pointed to this forum (with most of the questions going unanswered). He admitted that the 10Hz SSF is really about 12Hz. If you're saying the top dog suggested you do your own testing on your device to be sure it's doing what you want it to (and he's suggesting it may not), that brings to mind serious issues with the reliablity of the product. If SturmMD's new mule does what the B2 does but more reliably then sign me up :D (especially if the cost is similar).
 

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Hi Sturm,

Can you give more details about the project? Is this intended to be produced so that anybody can buy? Do you expect a release date soon?
 

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Hmm. I have tried contacting Bob @ CSS a couple times with questions about the Reckhorn B2 but I keep getting pointed to this forum (with most of the questions going unanswered). He admitted that the 10Hz SSF is really about 12Hz. If you're saying the top dog suggested you do your own testing on your device to be sure it's doing what you want it to (and he's suggesting it may not), that brings to mind serious issues with the reliablity of the product. If SturmMD's new mule does what the B2 does but more reliably then sign me up :D (especially if the cost is similar).
Oh, the ED ssf works, it's just that the freq adjust is not precise, meaning that you don't KNOW that it is set at a particular freq, but rather an estimate. So, given you have a tuned sub (which is why you need a ssf, right???) you'll typically want to set your ssf freq a bit lower, but with these devices you don't KNOW the freq you've set the ssf.

Sturm's device, at least to me, would be worth more than the off-the-shelf devices currently available, even if you have to build it yourself from a parts list. (I better start saving!)
 

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but with these devices you don't KNOW the freq you've set the ssf.
Why not just test the device with REW and make some marks on the dial? I wouldn't trust a device even if it had marks on the dial - I'd want to test it myself and look at the curve. It takes only a few minutes to do...

brucek
 

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Old computer, no rew...my opinion is unless sturm's design is either faulty or quite costly, manufacturers should be making a better mousetrap rather than expecting the consumer to (unnecessarily) have additional (costly) equipment to use their device accurately and follow up my making marks on the face.

Could you imagine after purchasing your automobile having to buy a radar gun and test your vehicle throughout the speedometer's range, and then write the actual speeds on the dash with a sharpie???:D
 

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Not only that, but testing the accuracy of your SSF in room is pretty difficult given all the interactions with room boundries. One would need to take your box outside and lift it up with a fork lift a la Kevin Haskins. Hard to do with an IB sub.
 

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manufacturers should be making a better mousetrap
There's a cost involved with that. We're discussing ~$100 devices here. I don't expect much from these cheap boxes.

testing the accuracy of your SSF in room is pretty difficult given all the interactions
The suggestion was to test the device with REW, not test the sub. It's a simple electronic sweep of the device itself to obtain a response graph - no room, no sub.

brucek
 

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There's a cost involved with that. We're discussing ~$100 devices here. I don't expect much from these cheap boxes.

The suggestion was to test the device with REW, not test the sub. It's a simple electronic sweep of the device itself to obtain a response graph - no room, no sub.

brucek
That makes more sense :duh:... and would be pretty easy to do. The only risk is it may be like luck of the draw on accuracy. The 10Hz SSF may be 12Hz but it could be 14Hz. Same with the boost at 20Hz. I suppose if a device tests inaccurate enough one could return it... but then shipping costs get involved. Do you take a chance on a second device that may be better or possibly even worse? I suppose it depends on the whether the manufacturer pays for shipping.
 

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SturmMD. Sorry for going OT. Your device looks cool and I can't wait to see how it turns out. If your device is more accurate than your comps then you will have a real place in the market. Good luck.
 
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