Well, here is my story.
Sonodyne, as a company sucks.
Although they know how to perfectly knock off Genelecs and that's the reason some of their speakers sounds and measures really good. No doubt on that.
But as a company, based on reliability, management, handling, it sucks bigtime.
So I bought SM300 pair with a pair of SLF312 subs.
Now, SM300 shows port chaffing noise at around 97 dBSPL which may be okay because no one's gonna monitor at 97dBSPL anyway.
It has bracing. But they used hollow metal rods as braces. Still can't find why they were trying to save like 10 USD (at max) per speaker by not using a 12mm-ish Solid metal rod and instead using12mm-ish hollow metal (most probably Iron) rod.
Much like Genelecs, they do use a Noratel transformer. They use BB 24/48 conversion. If there were some Digital Input capabilities, it would be great, but anyways...
The class A/B amped Tweeter have a pretty good Hiss at idle. My room has 27dBA noise floor and I can hear it pretty good. But let's not start nitpicking.
The Transformer does make some noise. It would have been better to use an SMPS instead.
But now comes the worst part.
Sonodyne engineers don't know shit about REW, Step Response, how one can get the Waterfall etc and this was pretty perceivable while talking to them.
So basically, if reliability is you first concern, it is a big NO NO.
But again, sounds and measures good.
SM300 was dsp balanced.
Now, the blunder.
SLF312 is analog.
Sonodyne couldn't rip off anyone.
So they made or designed one themselves.
One of the worst subs ever.
It is a 12" sub with two flared backports.
Now, as per their LMS Measurements and mine with 6 cycle FDW (although my room is absorptive down to 20Hz and I didn't need FDW but still did it anyway), the port is tuned very very narrowly around 37-38 Hz and the port has a steep 24dB/Oct roll off.
Now only the driver, has an Excursion protection HPF at 40Hz, that too at 24 dB/oct.
I measured everything exactly as per how the LMS manual states.
The results are basically around 48dB/Oct roll off.
So from 40 to 30, SPL lost was 15.8 dB.
Their stated FR, on website says, -3 at 30Hz and -10 at 25Hz which is roungly 24 dB/oct. Which is fine from a ported sub still. But inside the manual that came with the box, it said, -6 at 30Hz and -10 at 25Hz which translates to within 12-18 dB/oct Roll off slope.
But their OWN LMS Measurements and Mine (which were pretty much same) didn't measure anywhere near stated response.
Oh, I didn't tell you. But right after I bought the two subs, they were off by 6dB wrt each other. So their sensitivity was not matched.
I asked them to repair and at first they were bit BSing.
So, a senior mentor of mine, Rhitabrata Kar (He posted above as well, named RBKOnline) helped me and I talked to the owner of Sonodyne and then after like 5 days of purchase, they took the sub. They then did something (refused to tell me what they did, and called it a "Trick of Trade") and after 25 days, came back with the subs. They were still rolling off before 40Hz at the same slope. I asked them to take the subs and refund me. Thankfully, I got refund.
But I will never tell anyone to go for Sonodyne if they are wanting reliability. But atleast the SM300 sounds and measures excellent and as per specs.
Well, now I have BIC AMERICA PL300 and with one EQ moveto tame the BIC's proprietary low Q Peaky response, I have flat (+/- 2dB at 1/48dB/Oct smoothing) till 15Hz.
I am sharing my current response and current setup image as well.