The guy lives in So Cal. I believe he uses english as a second language. Calling his product low end is probably not a fair assessment.
His principle is sound, he uses a series resistor and a custom wound second voice coil to get a correction signal. This is not as effective at distortion reduction as an accelerometer based system, but it is still much better than an uncontrolled driver.
A gentleman on another forum went to visit the designer and said the subs sound OK, but that the designer never really cranked them. For the price he was asking for them at the time you could not build it yourself...
His principle is sound, he uses a series resistor and a custom wound second voice coil to get a correction signal. This is not as effective at distortion reduction as an accelerometer based system, but it is still much better than an uncontrolled driver.
A gentleman on another forum went to visit the designer and said the subs sound OK, but that the designer never really cranked them. For the price he was asking for them at the time you could not build it yourself...
I wasn't trying to be smug - just meant that cost was low. In fact, just my budget!
despite the language barrier I thought he made some very interesting points about recording site room gain, ambient sound and other issues. In fact, I am thinking seriously about offering to proof read/correct his site for free. Also his enclosures look really nice.
I did subsequently find a comment here where someone said their Rythmik Directservo sub didn't have enough 'punch' for HT and that it bottomed out too easily. This does seem to correlate with your information from the other forum.
thanks
despite the language barrier I thought he made some very interesting points about recording site room gain, ambient sound and other issues. In fact, I am thinking seriously about offering to proof read/correct his site for free. Also his enclosures look really nice.
I did subsequently find a comment here where someone said their Rythmik Directservo sub didn't have enough 'punch' for HT and that it bottomed out too easily. This does seem to correlate with your information from the other forum.
thanks
I can't comment on Rythmik's Direct Servo sub but I will comment on the way he does business. I bought a one of his 350SE (?) plate amps and Brian offered superb customer service. The amp works and sounds great and his follow up was exceptional. I highly recommend both Brian and the products he sells. Whether his sub meets your expectations in your application is something you'll need to decide.
HTH
Jim
HTH
Jim
Javaman said:
I second that about service Brian provides - it's first rate!
I have a DirectServo project in progress currently - enclosure has been glued together and I'm continuing tomorrow.
I'm building my subwoofer into a bit over 50 liters (internal volume)sealed enclosure. I don't mind the reduced sound pressure since my goal was to get really tight high quality bass with nice extension. A hifi-subwoofer to extend the frequency response of my Dynaudio bookself speakers.
...and that happens with the expense on SPL. If I would have used vented configuration I would have get at least 6 db's more. It is also going to be used in my home theater but two channel listening takes 95% of my equipment usage time.
I have a DirectServo project in progress currently - enclosure has been glued together and I'm continuing tomorrow.
I'm building my subwoofer into a bit over 50 liters (internal volume)sealed enclosure. I don't mind the reduced sound pressure since my goal was to get really tight high quality bass with nice extension. A hifi-subwoofer to extend the frequency response of my Dynaudio bookself speakers.
...and that happens with the expense on SPL. If I would have used vented configuration I would have get at least 6 db's more. It is also going to be used in my home theater but two channel listening takes 95% of my equipment usage time.
I just wanted to continue to my previous post that it's ready. Looks came out as planned and so does the sound. Tight, accurate and nice extension. Goal was to make a high quality musical sub and I think project was a succes.
I attached a couple of pictures of the finished sub. It's made from birch and waxed several times. The speaker beside the sub is Dynaudio Audience 52. This picture is from the front...
I attached a couple of pictures of the finished sub. It's made from birch and waxed several times. The speaker beside the sub is Dynaudio Audience 52. This picture is from the front...
Attachments
That's strange - I can see the pictures. Since I'm a 'newbie' poster on this forum my messages are not shown instantly. When I left my post I didn't see my it or the pictures. But now both are shown - for me anyway...?
Let's make a test - I'm attaching one more picture that shows nicely the difference in the color between top and the sides.
Let's make a test - I'm attaching one more picture that shows nicely the difference in the color between top and the sides.
Attachments
I guess the best - kind of - word for the sound is 'invisible'. I haven't noticed any technical faults (hiss etc.) or 'musical' shortcomings. It works as good amp should - not to be noticed but present the music as it is. It also has power and impact more than enough for myself.
I have not XO'd my main speakers at all: I have adjusted - by purpose - my system so that the sub continues where main speakers naturally roll off. The sub XO is adjusted to the minimum which is 40hz.
I have not XO'd my main speakers at all: I have adjusted - by purpose - my system so that the sub continues where main speakers naturally roll off. The sub XO is adjusted to the minimum which is 40hz.
Downfiring?
Hey Mobster,
Nice sub you have there. I am looking at doing the same thing and was wondering about the downfiring configuration. My quick scan of the Rhythmik site didn't turn up any recommendations on that, but checking the calculation given on the parts-express formula page I think that woofer may suffer from sag.
Unless I am calculating it wrong. The specs given on the Rhythmik Audio site indicate 1.2" peak-to-peak excursion and fs=26hz. I interpret that to mean Xmax=15mm, giving about 15% sag.
Any comments from more knowlegable sources?
Thanks,
/Dave
Hey Mobster,
Nice sub you have there. I am looking at doing the same thing and was wondering about the downfiring configuration. My quick scan of the Rhythmik site didn't turn up any recommendations on that, but checking the calculation given on the parts-express formula page I think that woofer may suffer from sag.
Unless I am calculating it wrong. The specs given on the Rhythmik Audio site indicate 1.2" peak-to-peak excursion and fs=26hz. I interpret that to mean Xmax=15mm, giving about 15% sag.
Any comments from more knowlegable sources?
Thanks,
/Dave
Let's see... If I use the formula on the PartsExpress page:
Percentage of Sag = 981,000 / (Xmax * (2 * Pi * Fs)²)
The woofer has 1.2" peak-to-peak excursion which means it has 0,6" of Xmax. That translates into 15,24 mm of Xmax. FS is 26hz.
Let's use the formula:
"(2 * Pi * Fs)²" = (2 * 3,14 * 26)² = 26660
15,24 mm * 26660 = 406298,4
981000 / 406298,4 = 2,41
So the answer is 2,4% sag.
Not so much I think?
Percentage of Sag = 981,000 / (Xmax * (2 * Pi * Fs)²)
The woofer has 1.2" peak-to-peak excursion which means it has 0,6" of Xmax. That translates into 15,24 mm of Xmax. FS is 26hz.
Let's use the formula:
"(2 * Pi * Fs)²" = (2 * 3,14 * 26)² = 26660
15,24 mm * 26660 = 406298,4
981000 / 406298,4 = 2,41
So the answer is 2,4% sag.
Not so much I think?
Riiiiight...
Of course you are correct.
I was interpreting the result of the calculation as total sag in mm and calculating 2.4mm/15.2mm =15%
/slaps forehead in disgust/
Thanks, I will try to restrict my algebra work to mornings when my blood-caffiene levels are at more reasonable concentrations.
/Dave
Of course you are correct.
I was interpreting the result of the calculation as total sag in mm and calculating 2.4mm/15.2mm =15%
/slaps forehead in disgust/
Thanks, I will try to restrict my algebra work to mornings when my blood-caffiene levels are at more reasonable concentrations.
/Dave
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