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Offline frank23  
#41 Posted : 26 December 2013 21:57:07(UTC)
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They come in 6-4-6mm and 8-6-8mm and are glued together under pressure. They say they can cut them using water jets in any shape that can be programmed on a cnc device, but only at right angles, no 45 degrees.
Offline phil page  
#42 Posted : 27 December 2013 02:07:55(UTC)
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Any idea what the lossy visco-elastic layer is here?

Posts have not altered in width on my iPad
Phil
Offline Simon Briggs  
#43 Posted : 28 December 2013 20:09:20(UTC)
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Greedy as I am will be looking at 2 speaker designs 1/ A 10" Seas based system using 2 or 4 drivers per side force cancellation and some mass damping

If 4 units are used the drivers will have some mass loading to lower overall sensitivity and system resonance.

The second will be a classic three way very tenuously influenced by the classic NS1000 in appearance, but using a single 15" a very high quality 6" bass/mid and tweeter.

Much fun will be had in 14!!

Edited by user 28 December 2013 20:12:26(UTC)  | Reason: Not specified

Offline ashleym  
#44 Posted : 29 December 2013 17:17:52(UTC)
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Quote:
a classic three way very tenuously influenced by the classic NS1000 in appearance


Or PM's much loved PMC IB2s?

Great ideas, really looking forward to your developments........nice to see how things progress (hint hint)

Speaking of looks, a lot of what you remember is based on the drive units and surrounds with many speakers being simple rectilinear shapes. The NS1000 having their units in a b shape layout but the NS1000x and 10000 had their drive units in a line. However what I really remember is the unusual drive units and the level controls. And with 3 units in a row you gain cabinet space without having to make a deep box. The limiting factor here is your cabinet making skillsThumbDown ThumpUp
Offline frank23  
#45 Posted : 31 December 2013 15:37:33(UTC)
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Originally Posted by: phil page Go to Quoted Post
Any idea what the lossy visco-elastic layer is here?

Posts have not altered in width on my iPad


The stuff is called Isomat, and can also be bought separate for applying it to steel plates or so.

This is a dutch document with some graphs and numbers: http://www.noisecontrol....nden/Isomat%20KE%20NL%20(NCS.P.3120.1.1).pdf
Offline darkmatter  
#46 Posted : 23 June 2014 22:27:53(UTC)
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About to start construction work on one design, I will not say too much about that design at the moment Smile

Edited by user 23 June 2014 22:28:24(UTC)  | Reason: Not specified

Offline darkmatter  
#47 Posted : 05 February 2016 12:35:54(UTC)
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Revisiting this thread for a few new ideas

I may split and start two new threads.

I have a pair of cabinets built from the above going spare 170 Litres in birch plywood well braced with demountable baffles.

I could populate these with either:-

One a // pair of Scanspeak 21W8555-XX bass drivers and a separate top mounted midrange enclosure both well braced and damped.

http://www.scan-speak.dk...heet/pdf/21w-8555-10.pdf

The advantage of this arrangement is that the bass alignment will be low Q, with fast well timed bass, with a top mounted two way mid enclosure narrow front with high quality midragne / tweeter and the position of which can be adjusted for time alignment in an adjustable array.

Or two

build a modern take of my BBC LS5/1AE with a high quality 15" bass unit crossing over to a pair of Audax TW034X0 tweeter What 15" unit to use PDN.153C01

This will involve an EBS3 alignment and crossover equalisation series inductor and // resistance to flatten the response.

Much fun to be had and see you in the new threads.

Edited by user 05 February 2016 12:39:23(UTC)  | Reason: Not specified

Offline phil page  
#48 Posted : 05 February 2016 23:54:21(UTC)
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If I were a betting man, I would bet that you will go for option 1.

Presumably with option 2 you would need to keep the xover freq well away from the vocal region - is this a problem?
Phil
Offline darkmatter  
#49 Posted : 23 July 2018 20:47:45(UTC)
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Originally Posted by: darkmatter Go to Quoted Post


The second will be a classic three way very tenuously influenced by the classic NS1000 in appearance, but using a single 15" a very high quality 6" bass/mid and tweeter.

Much fun will be had in 14!!


Wow 5 years ago!!!

Time flies with no progress!!

Back to this idea.

Just that I have the necessary drivers available and no budget

Drivers available

18" JBL 2245H https://www.jblpro.com/pages/components/2245H.pdf

8" Seas fill range H1597-08 FA22RCZ

Audax TW034X0 + Waveguide.

Stepped baffle to time align

Sealed box QT = 0.6 likely
Offline Shadders  
#50 Posted : 25 July 2018 20:37:27(UTC)
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Hi,
As an update to my active transmission line speakers - i based it on the Hifi News Richard MacDonald design - but then, they are all very similar. I used the Leonard transmission line software to model.

I did not use a tapered line, but with the relevant wadding and moving the bass driver down the line, the 2nd mode can be reduced to create a near flat response. The -3dB point is at 28Hz.

I am using a three way design - Volt B2549 Bass, SB Acoustics SB17NBAC35 Mid Woofer (240Hz to 2.4kHz), SB Acoustics Satori TW29RN Tweeter.

Had the cabinet CNC work completed, and i am currently adding the foam to the panels before construction. I sealed the MDF with primer before adding the foam. I am using a combination of 40mm egg crate acoustic foam and 12mm flat acoustic foam.

The internal design is not very good for construction as a business - as it will take too long for each speaker - so this is definitely a hobby only project.

I have completed the design for the active filtering - 4th order, using op-amps as opposed to DSP. I have completed my own amplifier design - which is voltage feedback, but may use a current feedback design in the future. I am using Neutrik SpeakON connectors, so this can be a straight amplifier swap.

Once i have completed the construction for one half (before i place the other side panel) i will upload some photos.

One of the pains is cutting the foam. Although i used a scalpel - there are small foam bits everywhere - so had a lot of work to clear those up, and the finish is rather coarse.

I was also surprised at the total cost for the foam - £120 total - and just about enough. Still have to buy the wadding.

Regards,
Shadders.
Offline darkmatter  
#51 Posted : 29 August 2018 10:14:07(UTC)
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Originally Posted by: Shadders Go to Quoted Post
Hi,
As an update to my active transmission line speakers - i based it on the Hifi News Richard MacDonald design - but then, they are all very similar. I used the Leonard transmission line software to model.

I did not use a tapered line, but with the relevant wadding and moving the bass driver down the line, the 2nd mode can be reduced to create a near flat response. The -3dB point is at 28Hz.

I am using a three way design - Volt B2549 Bass, SB Acoustics SB17NBAC35 Mid Woofer (240Hz to 2.4kHz), SB Acoustics Satori TW29RN Tweeter.

Had the cabinet CNC work completed, and i am currently adding the foam to the panels before construction. I sealed the MDF with primer before adding the foam. I am using a combination of 40mm egg crate acoustic foam and 12mm flat acoustic foam.

The internal design is not very good for construction as a business - as it will take too long for each speaker - so this is definitely a hobby only project.

I have completed the design for the active filtering - 4th order, using op-amps as opposed to DSP. I have completed my own amplifier design - which is voltage feedback, but may use a current feedback design in the future. I am using Neutrik SpeakON connectors, so this can be a straight amplifier swap.

Once i have completed the construction for one half (before i place the other side panel) i will upload some photos.

One of the pains is cutting the foam. Although i used a scalpel - there are small foam bits everywhere - so had a lot of work to clear those up, and the finish is rather coarse.

I was also surprised at the total cost for the foam - £120 total - and just about enough. Still have to buy the wadding.

Regards,
Shadders.


Shadders,

Very interested in this, as I have been asked to help a friend with his TL project.

DM :)

Offline darkmatter  
#52 Posted : 29 August 2018 10:16:01(UTC)
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My own project has evolved somewhat to a modular approach with separate decoupled mod and treble enclosures which will be positionable to gain some time alignment.

Sealed box for the bass.

DM :)
Offline Shadders  
#53 Posted : 29 August 2018 14:55:16(UTC)
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Originally Posted by: darkmatter Go to Quoted Post
My own project has evolved somewhat to a modular approach with separate decoupled mod and treble enclosures which will be positionable to gain some time alignment.

Sealed box for the bass.

DM :)


Hi DM,
As discussed - 2018_08_29_RV4564_TL_Generic_Design.png (19kb) downloaded 50 time(s). 2018_08_29_RV4564_TL_Generic_FreqResp.gif (20kb) downloaded 50 time(s).
Not sure if this has worked.
2018_08_29_RV4564_TL_Generic_FreqResp.gif (20kb) downloaded 50 time(s).
Regards,
Shadders.
thanks 1 user thanked Shadders for this useful post.
Simon Briggs on 29/08/2018(UTC)
Offline darkmatter  
#54 Posted : 24 November 2018 13:17:34(UTC)
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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 12 inch 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 textbook 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


12" Bass drivers are under consideration, just finding the right units. 15" or even 18" units are not an issue either as I am happy to house necessary sealed enclosures of Q=0.5 - 0.6)

I am still looking at using the 8" Seas FR unit with a tweeter in waveguide to cover the upper range, why not a pair of the 8" units per side either side of the tweeter/waveguide?

These 8" units look excellent as a upper bass / mid firstly Seas CA22RNY

Or from Jantzen a custom Seas JA 8008

Bass units remain the problem. At low cost but they have a decent set of parameters are these from BK Electronics AD 12-300? they model well in a Q=0.5 enclosure and could be used in multiples.




Offline darkmatter  
#55 Posted : 24 November 2018 13:20:31(UTC)
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Originally Posted by: darkmatter Go to Quoted Post
Originally Posted by: darkmatter Go to Quoted Post


The second will be a classic three way very tenuously influenced by the classic NS1000 in appearance, but using a single 15" a very high quality 6" bass/mid and tweeter.

Much fun will be had in 14!!


Wow 5 years ago!!!

Time flies with no progress!!

Back to this idea.

Just that I have the necessary drivers available and no budget

Drivers available

18" JBL 2245H https://www.jblpro.com/pages/components/2245H.pdf

8" Seas fill range H1597-08 FA22RCZ

Audax TW034X0 + Waveguide.

Stepped baffle to time align

Sealed box QT = 0.6 likely



My friend has decided to build a smaller system based upon 10" units and will go reflex I have whipped up a design which he is building

My own ideas still remain on paper and will do until I find something that I like.

Sealed box is the way for me to go.

Low Q of around 0.5 ~ 0.6

I will still be looking at many options.

The drivers that I have available to me without having to spend anymore than getting them re-surrounded (dreaded foam surrounds) are 4 number JBL 2245 18" drivers old but still viable?

18" JBL 2245H

old but still viable?
Offline darkmatter  
#56 Posted : 02 February 2019 11:28:23(UTC)
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What is quite interesting is looking back through and at the postings in this thread; mostly directed at my own ramblings contained in it!! The prime motive of this at the start was to basically research what is available in the marketplace and assessing what 15” (ONLY) drivers would work in a 150 -200 litre sealed box with an alignment resulting in a low Q of around 0.5. Conclusion very little.
What was going to evolve from this research, was a large 500 litre sealed box design using two 15” drivers. The resulting system will be a big 6 – 7’ tall but deep, slim looking vertical array looking like a big Duntech PCL 2001 loudspeaker if anyone is familiar with that one?

Other drivers would also be mounted in sealed enclosures, again with a low Q= 0.5. alignment.
Conclusions? Well sod all, precious little!! one could look at Car subwoofers, but they only suit small 50 litre or so squit boxes!! and for the excessive money charged and, in many cases, poor build quality and unsuitable electro / mechanical parameters, Grrrrrrr.

The only one I have found so far that works in a largish (250 litre) low 'Q' 0.5 ~ 0.6 max single driver cabinet is the SB Acoustics 15" SB42FHCL75-6 or possibly the Eminence LAB-15 - 15" driver.

The test results linked to below for the SB Acoustics 15 “Driver indicates good performance, Vance Dickason the test author of the link below wrote the excellent Loudspeaker design cookbook.

https://www.audioxpress.com/article/test-bench-the-sb42fhcl75-6-15-subwoofer-from-sb-acoustics

Some other drivers will still work in sealed enclosures, I have modelled several of drivers against the performance of the Yamaha NS1000 (my current bass performance favourite) and can replicate similarly the alignment that the Yamaha system gives albeit upscaled using other high-quality drivers such as the JBL2245H and the Volt RV4564. These will give possibly 25Hz performance in room, allowing for up to 9 dbs of room gain, but is that enough? It might have to be.

Another company Audio Technology (Skanning) offers the Flexunits which can be tuned at in the factory prior to dispatch to the customer and thus made to work in sealed alignments and may offer a possibility for the big sealed system mentioned above.

I will in no way or in any form compromise and touch any equalized alignments, many I have heard can sound convincing, but my fussy ears find faults every time I listen to them, I even find fault in some quite sophisticated system offered of late. Every blooming time!!
Guess I’m just very very sensitive to any of the sounds / performance results of using any bass EQ or LR transfers that are used in any loudspeaker systems?

Well the quest continues, but I am close to finding solace in the SB Acoustics 15” and the Audio Tech units. The JBL and Volt offer an alternative for me to consider albeit with me having to raise my desire to achieve full church organ bass in room and lift the desired system lower bass extension limit the project demands to 25Hz.

Simon
Offline darkmatter  
#57 Posted : 15 February 2019 11:46:57(UTC)
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I will be contacting Audio Technology (Skanning) soon as they can adjust the 15" bass unit to suit other alignments and applications, maybe sealed box as well?
Offline Martin Colloms  
#58 Posted : 18 February 2019 18:33:26(UTC)
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you mention 9dB gain at the lowest desired frequency but it rarely hits that spot
due to losses from the finite rigidity of the room boundaries
Colloms
Offline darkmatter  
#59 Posted : 18 February 2019 18:51:51(UTC)
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Originally Posted by: Martin Colloms Go to Quoted Post
you mention 9dB gain at the lowest desired frequency but it rarely hits that spot
due to losses from the finite rigidity of the room boundaries
Colloms


Very much an approximation, I estimated (up to) not exactly 9 dbs gain (a maximum) for my last listening room down to approx 20Hz, this was based upon various systems I used and measured over the years. I have not assessed (measured) my current room, however from my recent listening this may be less as the construction is different.

DM

Edited by user 18 February 2019 18:59:05(UTC)  | Reason: Not specified

Offline darkmatter  
#60 Posted : 29 March 2019 08:25:57(UTC)
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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


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