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DIY Speakers and Subs > Bossobass and Ultra Low Frequencies...
Scott Simonian's Avatar Scott Simonian 05:15 PM 12-30-2013
D-Box has been around for many years. I think it's a cool technology but I've only experience it once at a CES show. This was when they had moved away from their individual actuators and started making DBox theater chairs. The demonstration left much to be desired. I think it just needed to be dialed down. It was too in your face when it needed to be subtle, I think.

jpmst3's Avatar jpmst3 05:15 PM 12-30-2013
Quote:
Originally Posted by noah katz View Post

dunno, the dbox equipment is very pricey

Sure, but probably not more so than the digital projectors and 3D gear.
Adhoc1's Avatar Adhoc1 05:23 PM 12-30-2013
Has anyone tried out vibration dampers which have inherent resonance frequency in the usable range?

I'm thinking about something like these: https://sdp-si.com/eStore/Catalog/Group/1048
One would have to use a suitable number of them depending on weight of the sofa + persons in it. The ones in the picture have a natural frequency 6-30 Hz.

.
noah katz's Avatar noah katz 05:32 PM 12-30-2013
Quote:
Originally Posted by jpmst3 View Post

Sure, but probably not more so than the digital projectors and 3D gear.

I think 5 or 10 seats of dbox costs the same as a pj.
Quote:
Originally Posted by Adhoc1 View Post

Has anyone tried out vibration dampers which have inherent resonance frequency in the usable range?

The problem with that is that response would roll off below that, and you'd have a peak at resonance.

You could finesse it and have the peak at the very bottom, and EQ it down, saving power, but then things change depending on the number of passengers.

Simplest is to just keep the resonance below the operating range.
jpmst3's Avatar jpmst3 05:40 PM 12-30-2013
Quote:
Originally Posted by noah katz View Post

I think 5 or 10 seats of dbox costs the same as a pj.
The problem with that is that response would roll off below that, and you'd have a peak at resonance.

You could finesse it and have the peak at the very bottom, and EQ it down, saving power, but then things change depending on the number of passengers.

Simplest is to just keep the resonance below the operating range.

I don't know, I think the local theater owner told me that the digital pj was $150,000.
They are undoubtedly cheaper now, but no small investment.
Scott Simonian's Avatar Scott Simonian 05:44 PM 12-30-2013
How much does a run-of-the-mill D-Box go for these days? Way back when you'd get four actuators for a riser for a couch they were charging a hefty $20k. eek.gif
Adhoc1's Avatar Adhoc1 05:55 PM 12-30-2013
Quote:
Originally Posted by noah katz View Post

I think 5 or 10 seats of dbox costs the same as a pj.
The problem with that is that response would roll off below that, and you'd have a peak at resonance.

You could finesse it and have the peak at the very bottom, and EQ it down, saving power, but then things change depending on the number of passengers.

Simplest is to just keep the resonance below the operating range.

Hm, you mean something like Sylomer (cellular polyurethane), with lowest resonance around 7 Hz, used for floating floors etc?
noah katz's Avatar noah katz 06:06 PM 12-30-2013
Quote:
Originally Posted by Adhoc1 View Post

Hm, you mean something like Sylomer (cellular polyurethane), with lowest resonance around 7 Hz, used for floating floors etc?

Yes, though the resonant frequency would vary depending on the weight per effective area of supporting foam.
jmcomp124's Avatar jmcomp124 09:56 AM 12-31-2013
Quote:
Originally Posted by bossobass View Post

Yes, of course it's different for every soundtrack. Again, I picked this one because, other than the ULF content it's pretty unremarkable. As a result, no one has previously graphed it or remarked about it.

Here is the capture through the mic at the LP. I use no cal file for the mic or interface with spec lab so a bit of my actual response (what you experience at the seat during playback) is lopped off the very low end, but the SpecLab caps are pretty close to 4 Hz.

Hi Dave,
I am enjoying this thread and the wealth of information in your web-site. Thanks to Larry!
Your approach uniquely shines as it goes for the most accurate reproduction digging deep to the single digits and the spectrographs that show comparison to the reference standards is worth a thousand words. I want to start doing this sometime soon. With your raptor setup, while the in-room frequency response at the primary listening position is almost flat down to 3Hz, how about Max SPL in the lower octaves? Do you have Max SPL sweeps (covering down to 3Hz) that you can share? Also it will be very interesting to see power compression at these low frequencies. I currently have a passive radiator design and have always thought about single digit frequencies that my current design is not capable of.
Regards,
-Jai
bossobass 07:11 PM 12-31-2013
Quote:
Originally Posted by jmcomp124 View Post

Hi Dave,
I am enjoying this thread and the wealth of information in your web-site. Thanks to Larry!
Your approach uniquely shines as it goes for the most accurate reproduction digging deep to the single digits and the spectrographs that show comparison to the reference standards is worth a thousand words. I want to start doing this sometime soon. With your raptor setup, while the in-room frequency response at the primary listening position is almost flat down to 3Hz, how about Max SPL in the lower octaves? Do you have Max SPL sweeps (covering down to 3Hz) that you can share? Also it will be very interesting to see power compression at these low frequencies. I currently have a passive radiator design and have always thought about single digit frequencies that my current design is not capable of.
Regards,
-Jai

I have this one, but I cut it off @ 5 Hz.



I have another one where I pushed them a bit further, but I can't find it right quick (these bloody Mary's might have something to do with that). biggrin.gif

This was not my new Raptor System, which includes my newly redesigned amp and BHT-15 drivers. I'm not ready to show that one yet. smile.gif Still, it indicates that reference level to < 5 Hz without compression is a certainty in my room.

Sine sweeps below 10 Hz are not a good indication of what a system can do with WOTW, et al. REW generates a linear sweep from DC-10 Hz, then a log sweep from 10 Hz and up. Even then, the havoc wrought on the system and the structure is exponential to > 10 Hz sweeps. I actually hate doing it because it's a brutal assault on room and person and, other than the similarity to outdoor GP compression sweeps, it really doesn't say much more than what the system can do in-room while playing sine sweeps.

I wish Larry could have showed up just a few weeks later because when he was here I didn't have the new amps yet and the system as he heard it wasn't finally tweaked. Just yesterday I mentioned to my son that recent movie watching has me floored at how well the subwoofer system is performing... like nothing I've heard to date. He told me it's just been a long span of time where I never stopped looking for a weak spot to redesign and the improvements, although many were just slightly incremental, have summed to what I'm listening to today.

I'm actually quite proud of what years of chipping away at accuracy in-room to whatever bandwidth the disc asks for has resulted in. Very soon my analog PEQ will be ready for testing and that will put the icing on the cake of what I believe is the cleanest, most compact, most versatile and widest bandwidth system on the planet without having 40 or more cubes of boxes and multiple amplifiers in the room.

I wanted to take this opportunity to mention my eldest son who is the electronics genius of the house and has built the analog SEQSS and PEQ, tweaking them to perfection over 2 years time. They're dead quiet, flat to DC with no DC offset, do not clip under the most demanding scenarios to reference level, have the best components (after auditioning and measuring many versions), are factory adjustable, are deadly accurate and have a power on LED that changes colors to let you know when the real deal is being fed into them. Most importantly, they're specifically made for insertion between soundtrack source and the new amplifiers.

Without that card to play, I never would have been able to get what I designed on paper. It's just not commercially available and it would have taken the rest of my life if I had to do it myself. I would've had to buy some digital POS and live with it.

Here's to everyone... have a great NYE. smile.gif

Actually, Larry... well, this is his thread so I'll just say you might want to keep an eye on this thread over the next couple of months. cool.gif
popalock's Avatar popalock 07:52 PM 12-31-2013
Bloody Mary's huh? Bringing in the New Year right! Happy 2014 all.
jmcomp124's Avatar jmcomp124 08:14 PM 12-31-2013
Quote:
Originally Posted by bossobass View Post

I have this one, but I cut it off @ 5 Hz.



I have another one where I pushed them a bit further, but I can't find it right quick (these bloody Mary's might have something to do with that). biggrin.gif

This was not my new Raptor System, which includes my newly redesigned amp and BHT-15 drivers. I'm not ready to show that one yet. smile.gif Still, it indicates that reference level to < 5 Hz without compression is a certainty in my room.

Sine sweeps below 10 Hz are not a good indication of what a system can do with WOTW, et al. REW generates a linear sweep from DC-10 Hz, then a log sweep from 10 Hz and up. Even then, the havoc wrought on the system and the structure is exponential to > 10 Hz sweeps. I actually hate doing it because it's a brutal assault on room and person and, other than the similarity to outdoor GP compression sweeps, it really doesn't say much more than what the system can do in-room while playing sine sweeps.

I wish Larry could have showed up just a few weeks later because when he was here I didn't have the new amps yet and the system as he heard it wasn't finally tweaked. Just yesterday I mentioned to my son that recent movie watching has me floored at how well the subwoofer system is performing... like nothing I've heard to date. He told me it's just been a long span of time where I never stopped looking for a weak spot to redesign and the improvements, although many were just slightly incremental, have summed to what I'm listening to today.

I'm actually quite proud of what years of chipping away at accuracy in-room to whatever bandwidth the disc asks for has resulted in. Very soon my analog PEQ will be ready for testing and that will put the icing on the cake of what I believe is the cleanest, most compact, most versatile and widest bandwidth system on the planet without having 40 or more cubes of boxes and multiple amplifiers in the room.

I wanted to take this opportunity to mention my eldest son who is the electronics genius of the house and has built the analog SEQSS and PEQ, tweaking them to perfection over 2 years time. They're dead quiet, flat to DC with no DC offset, do not clip under the most demanding scenarios to reference level, have the best components (after auditioning and measuring many versions), are factory adjustable, are deadly accurate and have a power on LED that changes colors to let you know when the real deal is being fed into them. Most importantly, they're specifically made for insertion between soundtrack source and the new amplifiers.

Without that card to play, I never would have been able to get what I designed on paper. It's just not commercially available and it would have taken the rest of my life if I had to do it myself. I would've had to buy some digital POS and live with it.

Here's to everyone... have a great NYE. smile.gif

Actually, Larry... well, this is his thread so I'll just say you might want to keep an eye on this thread over the next couple of months. cool.gif
Dave, Truly impressive and thanks for sharing! I sent you an email (listed on your site) yesterday. When you get a chance, would love to hear back from you.

Wishing you and everyone here reading this thread, a very happy and Blessed New Year!
Regards,
-Jai
laugsbach's Avatar laugsbach 11:21 AM 01-02-2014
Quote:
Originally Posted by bossobass View Post

I wish Larry could have showed up just a few weeks later

It looks like a return trip is in order…smile.gif

Quote:
Actually, Larry… well, this is his thread so I'll just say you might want to keep an eye on this thread over the next couple of months. cool.gif

You Bet!!!!

I am looking forward to it…smile.gif
laugsbach's Avatar laugsbach 11:29 AM 01-02-2014
Quote:
Originally Posted by popalock View Post

Bloody Mary's huh? Bringing in the New Year right! Happy 2014 all.

You got that right…smile.gif

I wonder how long of a drive it is to Chantilly, VA from Cincinnati, OH. ? biggrin.gif
popalock's Avatar popalock 02:00 PM 01-02-2014
Quote:
Originally Posted by laugsbach View Post

You got that right…smile.gif

I wonder how long of a drive it is to Chantilly, VA from Cincinnati, OH. ? biggrin.gif

7 hours 52 minutes.
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