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Re: Midbass slam [message #83101 is a reply to message #83054] Tue, 26 July 2016 15:28 Go to previous messageGo to next message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
Thanks for posting, looks great! Cool
Your right, the speakers blend into the furniture really well, they have the 15" driver right? I would love to hear them.
And do you use the sub? You mentioned before it has passive radiators?
Re: Midbass slam [message #83102 is a reply to message #83101] Tue, 26 July 2016 15:57 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
jonone wrote on Tue, 26 July 2016 16:28
Thanks for posting, looks great! Cool
Your right, the speakers blend into the furniture really well, they have the 15" driver right? I would love to hear them.
And do you use the sub? You mentioned before it has passive radiators?


Thanks Smile
Sorry the pics are sideways.

Yes, they use 15" jbl's.
Yes, I use the sub with most content. Theres one or two bass heavy recordings I own, where I prefer to turn it off, but most of my content benefits from some bass augmentation from the sub.

Yes, the sub is passive radiator design.

It does not quite integrate seamlessly with the mains.
I'm not sure if this is due to the sub being a little too far away from the mains laterally (over 4.5' left and right),
or if the passive radiator design doesnt blend well for some reason.

Im guessing the former (lateral distance) is the reason, since a passive radiator is really just another way (theoretically) of porting an enclosure.

When I incorporate the 3pi's I'm going to move this sub to the back (opposite side) of the room, to use as a distant sub crossed over low.
Re: Midbass slam [message #83105 is a reply to message #83054] Wed, 27 July 2016 09:19 Go to previous messageGo to next message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
Sub bass frequency' s are many tens of feet long, so 5ft from the speakers shouldnt make any difference.
In my opinion I would only use sealed for subs and you need drivers with huge magnets to control the cone, lack of control leads to boom in my experience and I cant see how a passive radiator is under control properly?

crossed over low enough it maybe ok, eq will probably help too, Your room will also benefit from the flanking subs as the room modes will be lessened and modes normally lead to one note boom.

Have you measured your rooms response?
Re: Midbass slam [message #83106 is a reply to message #83105] Wed, 27 July 2016 14:32 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
jonone wrote on Wed, 27 July 2016 10:19
Sub bass frequency' s are many tens of feet long, so 5ft from the speakers shouldnt make any difference.
In my opinion I would only use sealed for subs and you need drivers with huge magnets to control the cone, lack of control leads to boom in my experience and I cant see how a passive radiator is under control properly?

crossed over low enough it maybe ok, eq will probably help too, Your room will also benefit from the flanking subs as the room modes will be lessened and modes normally lead to one note boom.

Have you measured your rooms response?


I have not measured my room, in a way that I can look at a graph, but I have run sweeps and hz test tones.
I had discovered a huge null at 70hz (throughout the center of the room) and another at around 150hz.
I have since added considerable acoustic treatment, and had heard a significant improvement in bass response afterwards.

The trouble I've had with blending this sub with the mains, only comes when I try to cross over at 100z.
At 70hz, there is much less trouble integrating.
Perhaps im refering to the problem of localization instead of integration, but again, that could be reduced with a slightly closer (lateral) placement to the mains.

In theory, the passive radiator is supposed to vibrate back and forth in the exact same manner as the air-plug in a port tube.

I wasnt aware of the woofer magnet size being important, I always thought it was really a matter of how strong the magnet was, regardless of size.
I did notice that the actual "size" of the sub woofer magnet on this passive radiator sub is quite a bit smaller than the magnets on the Eminence lab 12's Im using for the 3pi subs.

I would not mind using a sealed design, and would also enjoy the smaller enclosure that (typically) comes with it.
I only thought that the larger, ported cabinet would be easier to drive, requiring less power, while having less woofer excursion/distortion, above the tuning frequency.

I have chosen to incorporate these 3pi subs to help with the notch in the upper bass, lower midrange, that inevitably comes in a residential environment/room.
Not so much for the extra LFE, that bottom octave (20hz-40hz).

I suppose the term "midbass modules" or "helper woofers" might be better descriptions, as to what I'm using the flanking subs for.
Re: Midbass slam [message #83107 is a reply to message #83106] Wed, 27 July 2016 15:40 Go to previous messageGo to next message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
A 70hz wavelength is 5meters long, so having the sub on the same plane as the speakers shouldn't make this a problem? 80hz is supposed to be omni directional, I take it you sit closer then 5m?
Using a lower crossover and volume is typical to get a lesser sub to intergrate, my old sub was better crossed over below 60hz, my midbass is clean at 150hz in the same position.( same plane as speakers)
I need to cross my nearfield over at 40hz as there is still a lot of energy from higher up as the filter in the lfe out of my av amp seems shallow.
You might find you need to use a similarly low crossover when you move your sub to the back of the room.
I'm sure the pi 3s will be great up front!
If Your not aware you can gauge motor strength by the bl spec of your drivers.

Re: Midbass slam [message #83126 is a reply to message #83054] Fri, 29 July 2016 06:06 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
Looks like the BL rating for my current scanspeak sub is 6.
The BL for the 3pi drivers is 15. Not sure what it all means.

With my current arrangement (mains placed along the short wall), I sit exactly 5.5 meters back from the mains.
Re: Midbass slam [message #83129 is a reply to message #83054] Fri, 29 July 2016 08:43 Go to previous message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
Bl is normally shown in tesla metres and the higher the number the stronger the motor.
So as long as there both shown in tesla meters the pi subs are a lot stronger.
Normally the stronger the motor the more control it had over the cone and a tighter sound as there is less overhang.

But I believe there is a balance between control and efficiency so a really high number is not always a good thing.
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