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Online darkmatter  
#61 Posted : 03 April 2019 10:34:12(UTC)
Simon Briggs


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Originally Posted by: darkmatter Go to Quoted Post
A friend has built a pair of Ripol subwoofers a kind of open baffle (boxless) system, this will be an interesting experience as he has finalised (set them up properly?) them. Need to dig the measuring kit out again to test them, he claims better than 20Hz extension in room, I think he has a real good 30Hz in room limit but not much lower than that, when I heard them earlier in the month they certainly don't provide that weighty room lock I am used to when experiencing serious bass at and below 30Hz. I have only heard that in very, very few systems.

Simon






I had another and extended listen to them, an interesting bass experience not the kind of LF grip (room lock) I am used to, but they did provide some content down to approx 25Hz. not dynamic in the normal sense but consistent and even LF delivery without any real nasties, i.e. miss-tuned or overlong ports etc. Timing was good but not exceptional

I'll have to have a go and design one for myself, not to build but to test the ideas.

Could be in my opinion a good match for the Quad ESL (63/57) if the right drivers were selected for the design. The design I listened to didn't have the right drivers to match the Quad.


Simon

Online Simon Briggs  
#62 Posted : 25 June 2020 14:32:51(UTC)
Simon Briggs


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Resurrecting this discussion, a friend has asked me for recommendations for bass units for a sealed box design and will be using them up to about 2-300 Hz or so.

A brief search.

Not many units out in the marketplace seem suitable for sealed box loading, the 15" SB Acoustics has been suggested in the past and may steer him towards this driver.

I did think about 18" drivers, but that will produce a system that is just too big for his needs and his situation. as he lives in a modern house. Not nice high 9.5 foot ceilings like my Victorian room.

Edited by user 25 June 2020 14:37:42(UTC)  | Reason: Not specified

Offline kengale  
#63 Posted : 25 June 2020 17:17:29(UTC)
kengale


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Originally Posted by: Simon Briggs Go to Quoted Post
Resurrecting this discussion, a friend has asked me for recommendations for bass units for a sealed box design and will be using them up to about 2-300 Hz or so.

A brief search.

Not many units out in the marketplace seem suitable for sealed box loading, the 15" SB Acoustics has been suggested in the past and may steer him towards this driver.

I did think about 18" drivers, but that will produce a system that is just too big for his needs and his situation. as he lives in a modern house. Not nice high 9.5 foot ceilings like my Victorian room.


Don't leave out Fane when looking for suitable drivers. Although they have in most peoples' minds a reputation for loud PA systems and not much else, they have a very wide range of LF drivers, and my own experience has been that they perform well to their specifications and are a lot more reliable than some of their competitors.

Online Simon Briggs  
#64 Posted : 25 June 2020 18:02:40(UTC)
Simon Briggs


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Originally Posted by: kengale Go to Quoted Post
Originally Posted by: Simon Briggs Go to Quoted Post
Resurrecting this discussion, a friend has asked me for recommendations for bass units for a sealed box design and will be using them up to about 2-300 Hz or so.

A brief search.

Not many units out in the marketplace seem suitable for sealed box loading, the 15" SB Acoustics has been suggested in the past and may steer him towards this driver.

I did think about 18" drivers, but that will produce a system that is just too big for his needs and his situation. as he lives in a modern house. Not nice high 9.5 foot ceilings like my Victorian room.


Don't leave out Fane when looking for suitable drivers. Although they have in most peoples' minds a reputation for loud PA systems and not much else, they have a very wide range of LF drivers, and my own experience has been that they perform well to their specifications and are a lot more reliable than some of their competitors.



Fane also now own Precision Devices and thay also make some great units, though an 18" and too big the PD186/2 will work well in sealed enclosures.
Online Simon Briggs  
#65 Posted : 27 June 2020 11:32:54(UTC)
Simon Briggs


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Originally Posted by: Simon Briggs Go to Quoted Post
Resurrecting this discussion, a friend has asked me for recommendations for bass units for a sealed box design and will be using them up to about 2-300 Hz or so.

A brief search.

Not many units out in the marketplace seem suitable for sealed box loading, the 15" SB Acoustics has been suggested in the past and may steer him towards this driver.

I did think about 18" drivers, but that will produce a system that is just too big for his needs and his situation. as he lives in a modern house. Not nice high 9.5 foot ceilings like my Victorian room.


Spoke to my friend maybe the 15" drivers are too big for his needs?

Searching the forum in detail, two of the best pieces of advice recieved to date, maybe he should look at these options?

Originally Posted by: Martin Colloms Go to Quoted Post
for speedy bass , not necessarily the most bass, I favour Qtc at 0.5 to 0.6 for a sealed box.

Thus I would trade , for a given allowable box volume a 12inch for a 15 inch to achieve it.

I am wary of too much equalisation and electronics ahead of it as with more supplies, power noise, extra ground routes

immediacy and fidelity may be impaired in favour of a notional text book frequency response.

The box size implies lots of panel area, so massive bracing and damping is a prerequisite if the journey is to be worth the effort and expense.

Martin Colloms




Originally Posted by: Martin Colloms Go to Quoted Post


DM will have to work hard to define the design and try to exclude the noise from all our suggestions.

Thiel and KEF have been working towards coincident, time aligned driver systems with proprietary drivers. The Quad gets there as of right.

Avalon is more time coherent than most with low diffraction narrow enclosure forms , tilted back to align the bass mid and treble start positions relative to the listener.

The resulting system CSD is particularly good, thanks to careful control of the effective driver working ranges. With these designs it is the attention to such detail which impresses.


My instinct for an enthusiast is a sealed box three way with a form narrowing with height, a true 8ohm impedance, , ie two of the '5ohm' bass drivers in series probably 220mm SEAS , .

probably the 160 mm Scan pulp cone wide range mid and a DXT soft dome tweeter.

We could try and firm up device type numbers from this broad suggestion.

Martin C

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