(Planning) Rebuilding Manger based system. Would love your thoughts. - Page 2 - diyAudio
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Old 21st October 2013, 11:03 AM   #11
Sin Bin
 
Join Date: Oct 2006
Default Woofer choices...

Hi Alex,

I think the Beyma 12 P80 ( Nd or Fe depending on cost ) will be your best overall bet.
There are a lot of guys on this site using this driver in high end two way systems with the Beyma TPL driver, crossing it over around 1,200Hz to 1,800Hz.
The Beyma TPL is an ultra fast Air Motion Transformer but a Pro version capable of PA SPL's.
They rave about the midrange dynamics and low end punch from the 12P 80 Nd, so I am sure it will match the speed detail of the Manger.
Also the power handling and XMax of the 12P80 will be needed when you Eq the low bass....The "audiophile" bass drivers with wimpy 2 inch voice coils and limited excursion will distort below 100Hz if you use Eq on them.

The attached photo's are of a Manger based two way using a 12 inch Beyma driver the 12LX60 in a sealed bass cabinet of just 50liters. I crossed it over and Eq'd it with the fantastic DEQX unit, 60dB per octave Linear Phase slopes at 330Hz....It was and remains the best two way I have ever heard.

At the London Audio show in 2005 I demo'd a pair of these playing The Gladiator soundtrack Battle scene...They filled a packed room with a tidal wave of instruments and the floor shook with the low rumble of the Kettle drums as the track fades...Most systems barely manage to suggest the drums are even there!

The voice coil inductance is not an issue in your application as you will be crossing the driver over below 800Hz ( approx. 300Hz to 350Hz would be ideal) and the only theoretical advantage of low voice coil inductance is that it extends the top end response of the driver.
The AE range of drivers( M series is the best by far ) all have very low inductance and can be used up to 2 or even 3KHz on axis.
But as ALL big drivers beam ( the bigger the driver the lower the frequency it starts to beam) ie move your head a foot or two off axis and the high frequencies disappear there is almost no real world advantage in having a 12 or 15 inch driver with very low inductance.

Have you decided on final crossover / DSP unit and open baffle or sealed?

Cheers
Derek.
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Old 21st October 2013, 09:50 PM   #12
alextab is offline alextab  United States
diyAudio Member
 
Join Date: May 2011
Location: Bay Area
I did read through that Beyma TPL/12P80Nd thread, it would be hard to argue against the Beyma!

I want to build a sealed system. For the near future the speakers will be near the back wall and closer to the side walls than is ideal. I will be using the built in Hypex DSP in the AS2.1000 initialy but would love to build something myself in the future.

For the Beyma 12P80Nd that will not have much natural bass extension in a closed box and require EQ for bass, what is the right way to model the enclosure?

Thanks for all the info and assistance!

p.s. Amazing looking speakers!
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Old 21st October 2013, 11:03 PM   #13
Sin Bin
 
Join Date: Oct 2006
Default Sealed bass cabinet design

Hi Alex,

To be honest with your powerful Hypex amps and DSP you don't need to model any sealed bass cabinets.... You are free of all the " traditional " stress of juggling the 3 variables ie cabinet volume Vs bass extension Vs efficiency.
Also the low cost of good Eq (free with the fantastic JRiver Media Centre) or moderate $50 to $100 Pro studio grade plugins like (FabFilter Pro-Q - Equalizer Plug-In VST VST3 AU AAX RTAS AudioSuite
& Blue Cat's Liny EQ - Low Latency Linear Phase Equalizer Plug-in (VST, Audio Unit, AAX, RTAS, DX) ) you can "room tune" your system to perfection whatever room you move to.

With a serious Pro driver like the Beyma it can handle all the low end Eq you will ever need when matching it to a Manger mid / top for domestic use....You wont run out of Xmax and power handling.

Using the spec sheet as a rough guide you can use anything from about 45 litres to 90 litres internal volume and just about any shape you like.
Make it aesthetically pleasing and structurally non resonant ( bamboo, birch ply, acrylic, synthetic stone, alloy etc) and the only thing that will vary with the cabinet volume is the efficiency....ie the bigger the cabinet volume the less low end Eq boost you will need.

You will get slightly better low mid performance ( transients / group delay) with the bigger cabinet volume. If it was me I would go for a non symmetrical 65 litre bamboo ( 18mm thick ) cabinet, Trapezoid shape with a 10 litre matching trapezoid Manger cabinet on top ( 10mm thick Sorbothane pad separating them) and set the Manger cabinet back a couple of inches to vertically time align the voice coils.
Hope this helps!
Cheers
Derek.
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Old 22nd October 2013, 12:16 AM   #14
alextab is offline alextab  United States
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Join Date: May 2011
Location: Bay Area
Awesome stuff - I think I have what I need now.

Thanks again
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Old 22nd October 2013, 10:11 AM   #15
diyAudio Member
 
Join Date: Feb 2011
Location: Colorado, USA
Quote:
Originally Posted by Overkill Audio View Post
Hi Alex,

To be honest with your powerful Hypex amps and DSP you don't need to model any sealed bass cabinets.... You are free of all the " traditional " stress of juggling the 3 variables ie cabinet volume Vs bass extension Vs efficiency.
Also the low cost of good Eq (free with the fantastic JRiver Media Centre) or moderate $50 to $100 Pro studio grade plugins like (FabFilter Pro-Q - Equalizer Plug-In VST VST3 AU AAX RTAS AudioSuite
& Blue Cat's Liny EQ - Low Latency Linear Phase Equalizer Plug-in (VST, Audio Unit, AAX, RTAS, DX) ) you can "room tune" your system to perfection whatever room you move to.

With a serious Pro driver like the Beyma it can handle all the low end Eq you will ever need when matching it to a Manger mid / top for domestic use....You wont run out of Xmax and power handling.

Using the spec sheet as a rough guide you can use anything from about 45 litres to 90 litres internal volume and just about any shape you like.
Make it aesthetically pleasing and structurally non resonant ( bamboo, birch ply, acrylic, synthetic stone, alloy etc) and the only thing that will vary with the cabinet volume is the efficiency....ie the bigger the cabinet volume the less low end Eq boost you will need.

You will get slightly better low mid performance ( transients / group delay) with the bigger cabinet volume. If it was me I would go for a non symmetrical 65 litre bamboo ( 18mm thick ) cabinet, Trapezoid shape with a 10 litre matching trapezoid Manger cabinet on top ( 10mm thick Sorbothane pad separating them) and set the Manger cabinet back a couple of inches to vertically time align the voice coils.
Hope this helps!
Cheers
Derek.
Why do you like bamboo?
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Old 22nd October 2013, 10:49 AM   #16
Sin Bin
 
Join Date: Oct 2006
Default Google Bamboo

Bamboo is the best of all natural materials for loudspeaker cabinets ( and shelves, racks supports etc), have a Google and you will be amazed....here are a few bullet points to start:

(1) Resonance / damping characteristics - superior to any wood or MDF, as Bamboo is not a wood, its a grass with a vast number of inter woven layers tightly bound in a very high density structure.

(2) Tensile strength - almost as strong as steel....Back in the 1990's, in Hong Kong I was 20 storeys up in a glass elevator watching the construction workers walk along Bamboo scaffolding poles and planks, they still use them today!

(3) Machine-ability and finish - very easy to machine and achieve accurate joints, easy to glue / bolt / screw etc.

(4) Asthetics - Beautiful, look at bamboo flooring and furniture...Easy to just polish or seal and have a lovely finish, no need for toxic chemicals or high energy oven baked finishing.

(5) Durability & Reliability - Very stable in a wide range of climates and humidity, not prone to drying out or swelling with seasonal air conditions.

(6) Environmentally - The best!
Bamboo grows faster than any wood, some species of Bamboo can grow by over 40 cm ( 16 inches) in 24 hours!! Bamboo plantations have a higher biodiversity of species than so called " sustainable" soft wood forests which are "managed deserts" with almost no other plant or animal life allowed.

Cheers
Derek.
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Old 22nd October 2013, 11:11 AM   #17
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Join Date: May 2002
Location: Switzerland
I like the looks of bamboo also very much. The downside is only that it is not as easy to get as Baltic Birch Plywood for instance.

Back to the Woofer choice: Has anybody ever tried a Beyma 10G40 ? At afirst glance it looks less modern and sexy and less beefy than the proposed Neo driver and it is also less efficient. But upon closer look the frequency response of the 12G40 looks less ragged and the 6mm x-max is calculated the old-fashioned way (Vc-length minus pol plate thickness divided by two) , while the more modern way of calculation is used on the newer driver's data sheet, giving a little larger x-max figures for the same driver. So the 12G40 might probably "shovel" more air than the 12P80Nd.

Regards

Charles
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Old 22nd October 2013, 12:25 PM   #18
Sin Bin
 
Join Date: Oct 2006
Default Bass driver choices

Hi Charles,

Hope all is well with you, what tasty projects are you working on these days?! Have you seen this remarkable little power amp board :

VSSA Lateral MosFet Amplifier

Massive bandwidth and ultra fast rise time / slew rate and superb phase / group delay....Perfect for the Manger!

The 12G40 http://profesional.beyma.com/pdf/12G40E.pdf
is a great value bass driver and I am sure I have read about some projects on the site which have had great results using it.
I have never used it so I can only speculate on a few points below...

Alex is not looking for ultra low bass and or high SPL and crossing over around 350Hz so I think the 40Hz to 450Hz band is the main focus and its quite a close call....
The 12G40 is slightly rougher with a 3dB dip between 300Hz and 400Hz Vs the 12P80 peak of 2dB over the 280Hz to 350Hz band...
Sensitivity is close at 100Hz with the 12G40 @ 93dB at 100Hz Vs 91dB for the 12P80.
The 5dB to 6dB lower Harmonic distortion of the 12P80 is worthwhile having over the 40Hz to 100Hz band, and the lower the drivers are pushed the bigger the advantage to the 12P80.

The 4 inch voice coil of the 12P80 is a real advantage over the 3 inch coil in the 12G40...Less thermal compression will be audible in the bass.

The biggest advantage of all will be the superior transient performance of the 12P80. Ratio of voice coil to cone ( active Vs drag) and the Mms to Bl ratio are the important features to me.

The 12G40 has a lighter 3 inch voice coil ( actively powered) and a heavier cone ( drag on the coil) ie 62g divided by 18.3Bl = 3.36
The 12P80 has a 4 inch coil ( actively powered) and a lighter cone ( drag on the coil) ie 56g divided by 23.1 Bl = 2.42.

Using this arbitrary test the 12P80 is 40% "faster" than the 12G40.
I think this is reflected in all the subjective comments from the guys using the 12P80 when they talk about the superb detail and texture as well as the punch and dynamics of the driver.
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Old 22nd October 2013, 12:44 PM   #19
diyAudio Member
 
Join Date: Feb 2011
Location: Colorado, USA
I plugged some TS parameters into Win ISD for the 12P80ND and it exceeds XMax at around 100 HZ with a LT eq even at low power. BTW, Win ISD thinks there's something wrong with the published TS parameters. Maybe I made a data entry error, but I had to keep deleting data until it would take it.

I've got bamboo cutting boards but never thought about using them for speaker cabinets. I'm guessing it's less dense than MDF so it would make for a lighter cabinet as well.
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Old 22nd October 2013, 01:20 PM   #20
Sin Bin
 
Join Date: Oct 2006
Wink Sim error?

Hi Audio magnate,

Bamboo has a far higher density than MDF...
A pallet of 8 by 4 sheets of 18mm Bamboo is heavy, expensive to import hence its very expensive...

Re your simulation, real world users and my own experience would suggest your sim is wrong!
I used the older Beyma 12LX60 in a 50 litre sealed enclosure and it worked beautifully...The 12P80 has a similar 4 inch voice coil and power handling but is optimised for superior mid bass and low midrange, the LX60 will go louder lower down but Alex does not need this.

There are several guys on this site ( a bunch in Norway for some reason?) using the 12P80 in sealed enclosures and Eq'ing the bottom end flat to 40Hz in room and using big amps....It works, its as simple as that.

Cheers
Derek.
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