Advice/help request: mini PPSL vibration-cancelling [mid]sub? (newbie) - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 1Likes
  • 1 Post By A9X-308
 
Thread Tools
post #1 of 4 Old 05-24-2020, 08:19 PM - Thread Starter
Newbie
 
Join Date: May 2020
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 0
Question Advice/help request: mini PPSL vibration-cancelling [mid]sub? (newbie)

Hello,

I am new to self-build audio. And the reason I came into it is a weird issue I have when the house is way too easy to excite by any shaking of a speaker in the 40-70 Hz range, especially if it touches the floor, but walls also have the effect. (I don't get any audio below 40 Hz; I have a Pioneer SX-315 AVR with its included 5.1 speakers - I really use 2.1 - and there is a high pass filter there at 40-45 Hz).

If I hold the sub on my outstretched arms the noise t the rest of the house does not happen. So this is about mechanical shaking.

The sub also does not sound well at all

So I want to build my own "sub". Not strictly what serious DIYers call a sub, as it needs to cover 45-200 Hz. The crossover is built into the AVR and can not be changed apparently, Moreover I am not yet replacing the satellite speakers. I do not need a lot of power at all, I'm listening from about a metre and don't do "heavy" music. What I need, however, is that the sub not shake *at all*, to avoid exciting the house.

And on this forum I found a discussion of a design that works like that, with vibration cancellation. I am not allowed to post links but the topic is called "PA380 PPSL design by LTD02".

I can not however just copy the design as I don't nearly have the space like that! Nor do I have the power requirements. This is a personal space listening thing, I can do with a pair of 6.5" to 8" drivers. And I'd like to have it comparatively compact too, though I understand that it has to be bigger than "just any" box for the same drivers.

Unfortunately I do have to go all the way up to 200 Hz so that has to be taken into account too.

I would really appreciate advise about designing a PPSL or other vibration-canceling box, and selecting speakers for it of course.

The best I know so far is a simple "box with speakers on both sides", which I could calculate as small as 20 L if I can get Dayton Audio DC160-4 drivers. I can turn one speaker around and in reverse polarity to make it PPSL (eliminating distortion is a nice thing when I want to listen at low volume and get all the details).

But I am interested in more advanced designs where perhaps the drivers are closer to each other, thus making vibration cancelling more effective.
Mikhail Ramendik is offline  
Sponsored Links
Advertisement
 
post #2 of 4 Old 05-24-2020, 10:08 PM
Advanced Member
 
Chris Popovich's Avatar
 
Join Date: Dec 2005
Location: Phoenix AZ
Posts: 806
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked: 364
Any dual opposed setup will cancel cabinet vibrations. If you're looking for even smaller than the drivers you linked, check out Tang Band W6-1139SIF. They're impressive and if you decide you want to go lower, they'll do it.

Chris
Chris Popovich is online now  
post #3 of 4 Old 05-25-2020, 05:10 AM - Thread Starter
Newbie
 
Join Date: May 2020
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 0
Thanks!

I ran SpeakerBoxLite which is all I really know how to use as yet.

The Tang Band W6-1139SIF. are a beast! Expensive(ish) but does have the power for this price, also seems tricky to make. To get the results I want including a low group delay, I seem to need a 12 l box and a 30 Hz port, but how do I fit the port into the box safely? Also seems like I need to be pretty exact in planning for volume.

The Dayton Audio DC160-4 are cheap and cheerful, won't really let me go lower if I ever have the amp for it, won't give me nearly as much power in the bass as things are, and require a 20 l box. In that box I can do a 30 Hz port to get perfect delay but sacrifice some bass (-4.5 dB at 45 Hz, group delay < 8 ms throughout the range) or a 40 Hz port for stronger bass at the cost of delay (-3.7dB at 45 Hz, group delay <= 11 ms); 30Hz should, I guess, give better detail at lower volumes?

The 30Hz port for this box comes out at 35 mm diameter 139 mm length, easy to fit into that box, but of course I should probably verify this in something more reliable than SpeakerBoxLite? In general, seeing as this is a first build, I am more inclined towards the DC160/4 seeing as they are cheaper and more forgiving of mistakes in box volume and port size. But certainly I'd love to understand how to plan the Tang Band option properly before making this decision.

Also: to maximize vibration cancelling I should probably want to bring the two baffles with the speakers close to each other, and place a few small wooden beams between them to make sure they are well connected mechanically? If I go for 20 l, allow 2 cm for ply thickness and 5 l for speakers and beams, I get 20 cm between the baffles and 40x40cm baffle size; the port will need to come in at the side and run parallel to the baffles I guess. I can then put this on the floor or, more likely, hang it on the wall by a side. Would this work or am I missing something?

I am trying to learn the ropes while picking the right design for a tricky situation.
Mikhail Ramendik is offline  
Sponsored Links
Advertisement
 
post #4 of 4 Old 05-26-2020, 05:01 PM
AVS Forum Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia
Posts: 8,734
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 2035 Post(s)
Liked: 1750
PPSL is easy.
1: Design the porting as if it were a dual driver box of any type. Determine total volume incl bracing, driver volumes etc.
2: Design manifold. For best HF, keep it as short as possible, and for lowest dip, don't make it cuboid; round the rear, interior wall as much as possible. HF limit will be about 1/2 wl of manifold depth. Manifold mouth should be Sd x 2 or greater. Add manifold volume into the total volume of the box to determine panel sizes etc.
3: Work out which way you want to mount the drivers and how you are going to be able to get them in position. Push/pull with one magnet assembly into the manifold does make an improvement.
4: Work out all the rest of the design details.
jjcook likes this.

“You are not special. You are not a beautiful and unique snowflake.” Chuck Palahniuk

Last edited by A9X-308; 05-26-2020 at 05:07 PM.
A9X-308 is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off