New DIY Mid High (90deg) - AKA PM90

[Peter Morris]

Re: New DIY Mid High

Hey Peter,

Seeburg is about an hour East of my old home in Stuttgart, Germany. They and another local company, TW Audio, had significant presence in the central European market and are both well respected. TW Audio is a bit more mainstream in their products, nothing really interesting or odd, but very good stuff and very well thought out. Seeburg is a bit more creative and as you noted, has some interesting products. Their mini line array cabinet is really hard to beat for Voice reproduction in reverberant spaces. I often rented one of their large horn loaded systems for outdoor concerts and always liked how smooth they were.

That being said, the TW Audio T24 is my absolute favorite cabinet so far. It's sound is incredibly coherent - the tonal balance doesn't change at all with distance, it just gets quieter. Two flown, one under the other, along with 4 of their double-15 subs a side is a hugely capable rig that fits easily in a 5x8 trailer. A few years ago I listened to them at ProLight and Sound in Frankfurt and thought they were doing a better job then even some of the high dollar line arrays.



Have you worked with the Powersoft amp modules? They look really promising, but I haven't seen pricing yet. If it's anything like the rest of the Powersoft line, they are going to be pricey.

Ciao
Simon

Thanks again Simon,

Being located in Australia I don’t get to see all the equipment you have in Europe – I mainly see D&B, L-Acoustic, Meyer, EAW, Turbo, Martin, EV and JBL.

I must say the T24N at 33Kgs and a peak SPL of 143dB looks interesting. I considered building a box similar to T24, but the longer DIY horn gives you a bit more SPL in the 100Hz to 250Hz range.

The BMS 4594HE also has an advantage when compared to other compression drivers, it goes lower and louder than most and the 2 way design mean more pristine VHF without diaphragm breakup issues that you get with typical large format compression drivers . (see my time domain plots in the above post)

Below is a rough Hornresp sim of my best guess of the T24 compared to the DIY mid/hi. I tried it with a couple of drivers, the T24 seemed to like a driver with a heaver cone. The top plot is with 2 x RCF 12N405 (1000w) and the bottom with 12N351 (650w). The plots are at maximum power. The DIY uses the 12N351 to minimise the weight - 3.3Kg saving per driver.

As you can see the DIY has a 2 – 3 dB advantage in the low-mid according to the sim … but that of course is not the real world.

I have also included a picture of the partly constructed DIY and one of my earlier designs - it uses 2 x 10" and the same HF horn with a 4594 and passive crossover.

 

[Simon Coffin]

Re: New DIY Mid High

Gents,

Reading through the documentation from Acoustic Power Labs, it seems their product can adjust delay times at a resolution of 6hz. If this is the case, and I couldn't find a maximum delay it could handle, the idea of having a passive version of the cabinet and using the APL1 to align the drivers would seem possible. Use a passive crossover to divide the spectrum and possibly do some basic tuning, then the APL1 to bring everything into amplitude and time alignment.

Can the Lake do this same type of frequency based time alignment or is this a feature unique to the APL1?

Ciao
Simon

 

[Peter Morris]

Re: New DIY Mid High

Gents,

Reading through the documentation from Acoustic Power Labs, it seems their product can adjust delay times at a resolution of 6hz. If this is the case, and I couldn't find a maximum delay it could handle, the idea of having a passive version of the cabinet and using the APL1 to align the drivers would seem possible. Use a passive crossover to divide the spectrum and possibly do some basic tuning, then the APL1 to bring everything into amplitude and time alignment.

Can the Lake do this same type of frequency based time alignment or is this a feature unique to the APL1?

Ciao
Simon

The short answer is no I don't think it will work. You have to remember that any correction you apply by preconditioning the signal will be applied to both the mid and hi through the crossover region. If they are not time aligned and a fighting each other, preconditioning the signal will not be a good solution. If you can get good smooth summation through the crossover even if the amplitude response is not flat it will work. This is what Nexo do with the PS15 in passive mode. In this case my best guess is that the time offset is too much to get this to work ... I may be wrong.

You use APL WORKSHOP software to generate a file (coefficients) for the ALP1’s FIR chip. The file can be exported to other FIR processors instead of the APL1, but the file format Lake uses will not allow this to happen. (not easily ... )

What’s interesting about this approach is that the correction curve is based on a power response.

“Measurement of the emitted sound power occurs in many (about one hundred or two hundred) points in space, arranged on an imaginary spherical surface (or its segment in the most important direction of radiation) around the speaker in which information is collected. In simpler terms: a measurer with a microphone in his hand draws an imaginary vertical lattice for about a minute (1 min=180 points). A specially developed program fixes the value of the sound pressure at separate points and later calculates sound (acoustic) power frequency characteristics (SPFR) where the factors of interference are eliminated. On the basis of these characteristics the correction curve is then synthesized. It is created to mirror the radiated sound power frequency response curve; one can now follow this curve at a level of precision unavailable in traditional equalizers. The fact is that a FIR, a filter with finite impulse response, is used as an equalizer in SPFR correction technology. This is nothing new for radio and communication engineering, but in sound engineering it has been used quite rarely.”

What I did was use FIR crossovers and all pass filters in the Lake to partially correct the phase response. The problem is if you flatten the phase response too much, especially if you are using any reflex load speakers you will end up with a lot of latency. I selected an FIR time of only 2.5ms and used an IIR crossover between the Mid/Hi.

I also tried a full FIR 4 way crossover; there is 180 degrees less of phase rap with this approach and it requires 2 x LM26’s for a stereo system. A minimum FIR time of 12.5ms is required to process the sub crossover. The FIR time required is proportional to the crossover frequency and filter slope.

To my ear, all thing being equal except phase, speakers with a flat phase response sound more real than those that do not. I think the critical region for this between about 500 – 6000Hz; accordingly I designed / processed this design to achieve that.

I also tried the double 10 and horn speaker that I posted a picture of above 2 way with a passive HF/VHF crossover and 3 way. It sounds a little bit better 3 way.

 

[Peter Morris]

Re: New DIY Mid High

I thought this photo may be of interest - It shows the 2 x 12" and where the compression driver is located with the horn flare removed. Not a lot of space between the 12's and the compression driver!

 

[Art Welter]

Re: New DIY Mid High

The BMS4594 compression driver also allows the crossover to be in the 650 – 800 Hz range and it has more output than a normal compression driver. This means the 12s can operate in their piston range and the dipole arrangement does not to cause any issues off axis. The only negative is the vertical pattern of the HF horn gets a bit wide down low. There is also a price $ for components of this quality – they are not cheap.

I also have to say how impressed I am with the 4594HE – the sound quality is stunning, when listening to a good recording the stereo image is so good that you don’t hear the speakers, the sound comes from imaginary instruments and singers behind the speaker, if that make sense. It sounds like you a listen to a set of big studio monitors.

Peter,

Nice work on your cabinet!

Although the 4594 is certainly a fine driver, it does not have much more (if any more) output in the 650 – 800 Hz range than a "normal" dome diaphragm compression driver, in fact, the "old reliable" EV DH1A has similar distortion at five watts in that region compared to a 4594 at only one watt.

For that reason, (and many others..) I decided to use offset horn loaded 10" drivers to cover around 80-800 Hz in my latest design, the SynTripP. Used neodymium drivers to keep weight under 34 pounds (15.5 kilos) for the 26.5" wide x 11.25" tall, 15" deep (67.3 x 6.075 x 38.1 centimeters) main cabinet which also incorporates a tilting stand mount adjustable over a 40 degree range. The secondary horn is 41" wide x 25.5" tall x 7.5" deep (104.1 x 64.8 x 19 centimeters), weighing about 5 pounds (2 kilos).

http://www.diyaudio.com/forums/mult...ual-single-point-source-horn.html#post4114406

Next step is getting an FIR processor, from what you have written, a Lake may be the next "trip" I take.

Cheers,

Art

 

[Jack Arnott]

Re: New DIY Mid High

Peter,

Nice work on your cabinet!

Although the 4594 is certainly a fine driver, it does not have much more (if any more) output......

Art

In my opinion, the biggest advantage of the 4594 (especially the HE), is that it has more clarity than any compression driver, or cone combination, that I have ever heard.

The high output, and HF from the same device/exit, are just added bonus'.

See Darren's "So, in a smallish area, speaking into a vocal mic, I sounded more like me than any other box I've listened to." comment.

 

[Peter Morris]

Re: New DIY Mid High

Peter,

Nice work on your cabinet!

Although the 4594 is certainly a fine driver, it does not have much more (if any more) output in the 650 – 800 Hz range than a "normal" dome diaphragm compression driver, in fact, the "old reliable" EV DH1A has similar distortion at five watts in that region compared to a 4594 at only one watt.

For that reason, (and many others..) I decided to use offset horn loaded 10" drivers to cover around 80-800 Hz in my latest design, the SynTripP. Used neodymium drivers to keep weight under 34 pounds (15.5 kilos) for the 26.5" wide x 11.25" tall, 15" deep (67.3 x 6.075 x 38.1 centimeters) main cabinet which also incorporates a tilting stand mount adjustable over a 40 degree range. The secondary horn is 41" wide x 25.5" tall x 7.5" deep (104.1 x 64.8 x 19 centimeters), weighing about 5 pounds (2 kilos).

http://www.diyaudio.com/forums/mult...ual-single-point-source-horn.html#post4114406

Next step is getting an FIR processor, from what you have written, a Lake may be the next "trip" I take.

Cheers,

Art

Thanks Art,

As part of my research I did have a look at your design, it looks great but I wanted something that looked a little more conventional for the work I do. If the size was not an issue I would have built a smaller version of Danley’s SH96HO optimised to work above 100Hz.

I have A/B the 4594 and the 4594 HE with some Eighteen Sound drivers - NSD1480N, ND1480 and RCF’s new ND850.

The BMS sounded much better; my ears told me exactly what Jack described above.

http://www.eighteensound.it/PRODUCTS/Products/CatID/3/ProdID=151#.VLg2a2kbrq4
http://www.rcf.it/en_US/products/precision-transducers/neodymium-compression-drivers/nd850

The distortion type, and the frequency where it occurs is the reason – the third harmonic is low in the critical mid band.
I used the HE version in this project. I don’t have any distortion figures for this driver but it has shorting rings and should have noticeably lower distortion.

Being a two way driver, the acoustic output is the sum of a 150 watt HF and an 80 watt VHF driver. On a single frequency sin wave test there is no significant advantage compared to a normal driver, but on a complex wave form there is a big advantage. Being able to coherently sum the outputs you can achieve much higher peak SPL’s. You can also design the VHF to be much more efficient, in this case something like 10 - 12dB at 10kHz compared to a DH1A.

Anyway … you need to get yourself a Lake (or similar) and some 4594HE’s to play with … love to see what you could come up with ~~:smile:

 

[Art Welter]

Re: New DIY Mid High

1)Being a two way driver, the acoustic output is the sum of a 150 watt HF and an 80 watt VHF driver.
2) On a single frequency sin wave test there is no significant advantage compared to a normal driver, but on a complex wave form there is a big advantage.
3)Being able to coherently sum the outputs you can achieve much higher peak SPL’s.
4)You can also design the VHF to be much more efficient, in this case something like 10 - 12dB at 10kHz compared to a DH1A.[/COLOR][/SIZE][/FONT]
5)Anyway … you need to get yourself a Lake (or similar) and some 4594HE’s to play with … love to see what you could come up with ~~:smile:

Peter,

1) The only region they sum is around the acoustic crossover, where the summation presumably would be flat response.
2) In my tests of BMS drivers:
http://soundforums.net/varsity/4329-high-frequency-compression-driver-evaluation.html
they did not perform as well (distortion wise) with single or dual sine waves as other drivers. The EV/BMS distortion figures agree. The output of the BMS is quite smooth though.
3) If one could sum the outputs of two drivers covering the same frequency range without air non-linear losses, the output could be as much as 6 dB more, JBL has a dual ring diaphragm driver that does that. The 4594HE do not do that, as mentioned in #1.
4) That is simply not the case, larger diaphragm area of a given material thickness results in more output. The HF diaphragm of the 4594HE is relatively small. If you were to attempt to get 10 dB more output at 10kHz compared to a DH1A, the 4594HE HF coil would vaporize.
5) Agreed on the Lake, but knowing just from the published figures that the 4594HE’s have less output potential in the crossover region than 3" diaphragm drivers costing far less does not pique interest to play with them. That said, if someone gives me a pair, I'll figure something out ;^)

Art

 

[Peter Morris]

Re: New DIY Mid High

Hi Art,

I have to agree that the DH1A is still an excellent driver. It was one of my favourites and I used it almost exclusively in my systems 20 years ago. As much as I love the old DH1A the 4594HE is definitely worth the extra money.
The BMS drivers you tested and compared to the DH1A were standard format 1" drivers with 1.75" polyester diaphragm, not the 4594HE. I’m not sure your implied conclusions based on those tests are that valid in respect to the 4594HE.

With respect to summation I said:

"Being a two way driver, on a single frequency sine wave test there is no significant advantage compared to a normal driver, but on a complex wave form there is a big advantage. Being able to coherently sum the outputs you can achieve much higher peak SPL’s. You can also design the VHF to be much more efficient, in this case something like 10 - 12dB at 10kHz compared to a DH1A."

The output of any speaker is the sum of the acoustic output of the drivers it uses. For example I posted a picture of 400Hz square wave. Without going into the math, you could say that it is actually made up of a collection of sine waves. 400Hz + 1200 + 2000 + 2800 + …… 6000 +6800 + 7600 + 8400 etc. (Fourier series for a square wave http://en.wikipedia.org/wiki/Square_wave)
In this case the 12" drivers are only producing a 400 Hz wave; the low section of the 4594 is producing 1200Hz + 2000 …. 6000, and the HF, 6800Hz + 7600 + 8400 etc. All of these bits add together to form a square wave. i.e. "the acoustic output is the sum of a 150 watt HF and an 80 watt VHF driver" … and the 12"

As part of a simple explanation, if we look at another example and compare a 2 way speaker with a 3 way speaker (with all the comparative components being equal) using a single tone the maximum SPL is the same for both speakers (power in multiplied by efficiency). If we use broad band noise or music it a different story, the energy is shared over 3 drivers instead of 2. If we assume the drivers are all 100 watt each and the crossovers frequencies are selected so that the load is shared equally, then the 2 way speaker can take 200 watts of energy and the 3 way, 300 watts. Assuming perfect summation the 300 watt speaker will be louder.

That’s exactly what happening in this case.

With regards to the VHF output, the plots you posted show the DH1A’s efficiency with a 5 watt input being about 105 dB on a 90 x 40 horn … or roughly 100 dB 1 W/ 1m. In comparison the VHF section of the 4594HE makes about 112 dB 1w / 1m on a similar horn and is rated for a similar input.

This is what 3 x 4594 per side will do when they are summed correctly on a good horn - https://www.youtube.com/watch?v=AkrZplo9xgM
http://www.danleysoundlabs.com/danley/wp-content/uploads/2014/09/JH90-spec-sheet.pdf
There are also some videos of a SH96H0 in action somewhere (?) that are very impressive that use 1 x 4594.

It’s also interesting note the difference between Danley’s standard SH96 and the high output, HO version which the only difference is a more powerful compression driver. (I believe a Faital Pro HF14T (?) V’S a BMS 4594)
You also mention JBL new D2 with the dual diaphragms. This idea was originally patented by (can’t remember his name) from BMS. JBL uses the duel diaphragms in a very similar arrange but I believe there in no legal infringement of the patent. Recently BMS in accordance with the original patent released this driver, arguably "the loudest audio transducer ever made". http://www.bmsspeakers.com/fileadmin/bms-data/product_data_2014/bms_4599nd_preliminary.pdf

Anyway as I said before … you need to try the 4594HE ~~:smile:

 

[Ivan Beaver]

Re: New DIY Mid High

You can also design the VHF to be much more efficient, in this case something like 10 - 12dB at 10kHz compared to a DH1A."

However there is a difference between sensitivity and max output.

Agreed that the VHF is more sensitive on the BMS-but it also has less power capacity.

It is the combination of sensitivity and power capacity that gives the maximum output.

There are many factors that make up the "total driver" (just like a loudspeaker system), not just a single aspect.

But all to often in our industry people get "hungup" on one aspect-hoping and thinking that the single "simple number" will describe the whole product performance in a way they like.

Same thing goes for cars and many other products. It is not just horsepower-but torque-and towing capacity-and passenger compartment size etc that make up the total package.

Some are better in some areas, while others are better in different areas-it just depends on what you are after and what your needs are for a particular product.

 

[Peter Morris]

Re: New DIY Mid High

However there is a difference between sensitivity and max output.

Agreed that the VHF is more sensitive on the BMS-but it also has less power capacity.

It is the combination of sensitivity and power capacity that gives the maximum output.

There are many factors that make up the "total driver" (just like a loudspeaker system), not just a single aspect.

But all to often in our industry people get "hungup" on one aspect-hoping and thinking that the single "simple number" will describe the whole product performance in a way they like.

Same thing goes for cars and many other products. It is not just horsepower-but torque-and towing capacity-and passenger compartment size etc that make up the total package.

Some are better in some areas, while others are better in different areas-it just depends on what you are after and what your needs are for a particular product.

Ivan,

The DH1A is rated at 75 watts

http://www.google.com.au/url?sa=t&r...n4GwAg&usg=AFQjCNGV5Kr1FWtbYKi4fcFDPbMyafmEcQ

The VHF section of the 4594 is rated at 80 watts

http://www.bmsspeakers.com/index.php?id=4594nd_specification

I would suggest that the DH1A rating is a little conservative and the BMS a little optimistic ... but 10dB more efficiency is a lot given they have similar power handleing!

As a further comparison the DH1A is rate at 114 dB / W / m 40 x 20 horn; the 4594 is rate at 118dB on a 40 x 20 horn, and the low section of the 4594 is rate at 150 watts. i.e the low section is 4 dB more efficient and takes 3dB more power ... 7dB more not to mention its operating in combination with an 80 watt VHF driver.

..... perhaps I'm wrong .... you may need to replace the HF driver in your J1s and SH96H0s with DH1A's :idea:8O~8-O~:shock: .... :razz:

My experience so far is the 4594 in use is probably about 6dB up on your typical large format compression driver. I'm sure there is a good reason why you guys are using it.

 

[Simon Coffin]

Re: New DIY Mid High

Hey Peter,

Being ever the practical thinker, I've been wondering how to organize your cabinet, a matching sub and all required amplification and DSP into a flexible, efficient and compact package. It seems to me that DIY solutions, while often having some truly brilliant engineering and skillful tuning, are single products that still need to be adapted to play well with other cabinets or DSPs. Their integration is left as an exercise for the user, leading to very mixed results and generally poor acceptance. As I mentioned in an earlier post, there is a gap in current speaker products between the speakers-on-sticks and small platform line arrays. This is the niche previously filled with classic hi-Q trap boxes that nobody is making anymore. Your cabinet sits right in this niche. Packaging the cabinet with matching sub(s) and amps would take it out of the 'just another diy box' into a system that I suspect would get a lot more attention and respect. At least that's the theory. There have been a few systems published in the past, Art Welter's comes to mind, but I can't think of one that was developed collaboratively and that was presented as a complete system, amps, subs, tunings and all.

So with that being said, here are my thoughts in no particular order:

Mid/High: As long as the cabinet stays tri-amped, the amp rack is going to be more expensive than is realistic for most weekend warriors. While it may give the cabinet a slight sound improvement, the third amp starts to push the system's costs into an uncomfortable area. A biamped cabinet, assuming the power needs are not horrendous keeps the total costs down, especially if a 4 channel amp could be used to drive two tops. A quick survey indicates there are quite a few 4 channel amps that could be used.

Subs: You mentioned you have an existing design for a double 18. If that is the case, I'd recommend well thought out stacking feet so the subs can be securely stacked on top of each other, or a mid high on a sub. This provides setup flexibility. Dolly boards that double as grill protection are also a good idea.

Flying hardware: I still think the Seeburg K24 is the role model for cabinets in this size range, allowing them to be flown one under the other at the optimal angle with built in hardware. You mentioned earlier that the horn was not optimal for arraying. Assuming the cabinets are arrayed one under the other, do you still think that would be the case? Both the RCF and Eighteen sound horns you mentioned are 50 degrees vertical. Although, with the cabinets flown, the 60 horizontal may make more sense.

DSP/Amps - I recently saw that the Ashly nxp amps are FIR capable. They are not cheap, ~$4000 for the nxp1.54 and a bit less for the nxp3.02. The Lake LM-26 is going for what ~$4000 and could drive less expensive amps, which may cost less in the end than two Ashlys. What do you think of a 5/6 space rack with a Ashly nxp1.54 driving two tops bi-amped and a nxp3.02 on the subs. Add a single space patch panel with left/right xlr in/out, Speakon outs and Powercon in/outs. Add the Lake if using non-dsp amps. This gives a lightweight, compact rack that should be able to drive the cabinets to their limits.

One of the things I thought was stunning about the TW Audio T24n and its matching B30 sub was they could be used as a standard system of two tops, four subs with one amp rack. Or if you needed more output you could double up with two tops and four subs per side. The scalability of this system caused it to punch way above its weight class. I sense you are going in the same direction, which would be fantastic.

I know when an idea is presented to a forum like this, it tends to get dissected and examined and pulled apart. Please don't think I'm being disrespectful. On the contrary, I think you have done some fantastic work. I, and I'm sure others, would like to see these ideas further developed.

Cheers,
Simon

 

[Peter Morris]

Re: New DIY Mid High

Hey Peter,

Being ever the practical thinker, I've been wondering how to organize your cabinet, a matching sub and all required amplification and DSP into a flexible, efficient and compact package. It seems to me that DIY solutions, while often having some truly brilliant engineering and skillful tuning, are single products that still need to be adapted to play well with other cabinets or DSPs. Their integration is left as an exercise for the user, leading to very mixed results and generally poor acceptance. As I mentioned in an earlier post, there is a gap in current speaker products between the speakers-on-sticks and small platform line arrays. This is the niche previously filled with classic hi-Q trap boxes that nobody is making anymore. Your cabinet sits right in this niche. Packaging the cabinet with matching sub(s) and amps would take it out of the 'just another diy box' into a system that I suspect would get a lot more attention and respect. At least that's the theory. There have been a few systems published in the past, Art Welter's comes to mind, but I can't think of one that was developed collaboratively and that was presented as a complete system, amps, subs, tunings and all.

So with that being said, here are my thoughts in no particular order:

Mid/High: As long as the cabinet stays tri-amped, the amp rack is going to be more expensive than is realistic for most weekend warriors. While it may give the cabinet a slight sound improvement, the third amp starts to push the system's costs into an uncomfortable area. A biamped cabinet, assuming the power needs are not horrendous keeps the total costs down, especially if a 4 channel amp could be used to drive two tops. A quick survey indicates there are quite a few 4 channel amps that could be used.

Subs: You mentioned you have an existing design for a double 18. If that is the case, I'd recommend well thought out stacking feet so the subs can be securely stacked on top of each other, or a mid high on a sub. This provides setup flexibility. Dolly boards that double as grill protection are also a good idea.

Flying hardware: I still think the Seeburg K24 is the role model for cabinets in this size range, allowing them to be flown one under the other at the optimal angle with built in hardware. You mentioned earlier that the horn was not optimal for arraying. Assuming the cabinets are arrayed one under the other, do you still think that would be the case? Both the RCF and Eighteen sound horns you mentioned are 50 degrees vertical. Although, with the cabinets flown, the 60 horizontal may make more sense.

DSP/Amps - I recently saw that the Ashly nxp amps are FIR capable. They are not cheap, ~$4000 for the nxp1.54 and a bit less for the nxp3.02. The Lake LM-26 is going for what ~$4000 and could drive less expensive amps, which may cost less in the end than two Ashlys. What do you think of a 5/6 space rack with a Ashly nxp1.54 driving two tops bi-amped and a nxp3.02 on the subs. Add a single space patch panel with left/right xlr in/out, Speakon outs and Powercon in/outs. Add the Lake if using non-dsp amps. This gives a lightweight, compact rack that should be able to drive the cabinets to their limits.

One of the things I thought was stunning about the TW Audio T24n and its matching B30 sub was they could be used as a standard system of two tops, four subs with one amp rack. Or if you needed more output you could double up with two tops and four subs per side. The scalability of this system caused it to punch way above its weight class. I sense you are going in the same direction, which would be fantastic.

I know when an idea is presented to a forum like this, it tends to get dissected and examined and pulled apart. Please don't think I'm being disrespectful. On the contrary, I think you have done some fantastic work. I, and I'm sure others, would like to see these ideas further developed.

Cheers,
Simon

The short answer to all your comments is – Yes.

3-way / 2-way.
The options are a passive crossover for the 4594HE or use one of the new 4 inch diaphragm compression drivers such as :B&C - DE1080TN, RCF - ND950 1.4, 18sounds - NSD4015N, Beyma CP855nd and Radian’s 951BP.

Someone may be able to provide some advice as to which would be the best. It needs to operate from about 700Hz up.

Flying Hardware.
I’m looking at some simple options from Penn Elcom in combination with some aluminum bracing that ties the top and bottom to the sides. I think the limit for a DIY in this case would be 2 boxes deep. The hard ware has to be rated and "off the shelf". - I'm not sure a DIY should even go beyond these comments.
http://www.penn-elcom.com/default.asp?MC=01180101

Subs
There is a plan for a double 21 ( B&C 21SW152) to go with this box. If you want a double 18 I would suggest that Luke’s design on this site looks good J

Stacking
One of the things I’m looking at is a way that two people can stack one of these boxes on a sub with an extension pole. Perhaps with a yoke like TW Audio’s T24n uses.

Arraying
The initial idea was not to array these boxes, just build a super powerful speaker on a stick. After listening to some of the comment here, perhaps I should look further. I think the answer is to use an eighteen sound XT1464 horn or maybe the XR version. It would also be an advantage if the box could be made trapezoidal … but that will make it difficult to build as a DIY project.

Processing
I think there are lots of options, it just depends on how far you want to push the envelope. I don't think it will need FIR filters to make it work.

I should also say that the reason I put this one the board when it was just a prototype was to obtain input form everyone in the hope that it would make the fineal box better. Its all helpful ... so thank you to everyone so far

 

[Peter Morris]

Re: New DIY Mid High

Its get there .. still need to sort out the fly-ware.

 

[Jason Joseph]

Re: New DIY Mid High

Nice job Peter looks great!

 

[Jack Arnott]

Re: New DIY Mid High

4) That is simply not the case, larger diaphragm area of a given material thickness results in more output. The HF diaphragm of the 4594HE is relatively small. If you were to attempt to get 10 dB more output at 10kHz compared to a DH1A, the 4594HE HF coil would vaporize.

Art

I do not understand this statement, at all. Obviously the BMS 4594 has higher sensitivity, and overall power handling (3x), than the DH1A.
And obviously, the high frequency diaphragms do not vaporize. The 4594 simply puts out way more sound than the EV.

 

[Ivan Beaver]

Re: New DIY Mid High

I do not understand this statement, at all. Obviously the BMS 4594 has higher sensitivity, and overall power handling (3x), than the DH1A.
And obviously, the high frequency diaphragms do not vaporize. The 4594 simply puts out way more sound than the EV.

Without getting into trouble-all I will say is that specs are one thing-and what actually happens are often different in the real world.

Of course it depends on what specs are being looked at-how they are measured/presented and under what test conditions.

You can get very different specs depending on how you look at things.

Even if you take the same measurement and a group of people-you can come up with different "numbers" for people looking at the same data.

 

[Jack Arnott]

Re: New DIY Mid High

Ah yes, the 10 db part. Guess that is important, and we need to get a dh-1 to vaporize also. But I am so confused by why the HF will vaporize, and why it needs to be specifically compared to the dh-1. Why won't the mid section vaporize? And the statement seems to compare the dh-1 as only going from 6k on up, and neglect the fact that it needs to go from 500hz to 6k also.

 

[Peter Morris]

Re: New DIY Mid High

What’s probably worth mentioning is that I have been using the 4594 for a while in another box. It has 2 x 10” Eighteen Sound drivers and is very similar to JTR's 3TX. It runs two-way active crossing over to the 4594 at 630Hz. Prior to using the 4594 it used an Eighteen Sound NSD1480N compression driver and crossed at 900Hz.

The version with the 4594 goes louder and sounds better…. It’s that simple.

The 1480 is an excellent driver but wasn’t happy going as low as I needed, If you crossed it at 1200Hz to 1600Hz it was great but there were issues with the two 10’s not wanting to play nicely together above about 800Hz.

http://www.eighteensound.it/PRODUCTS/Products/CatID/3/ProdID=151#.VMQto2kbrq4

In this case the double 12” has probably 10dB or more output than the double 10” because of the horn loading and more powerful drivers used in the mids.
I have been concerned how the 4594 would keep up and I have after a little bit of testing raised the crossover frequency of the HF to 800Hz. It sounds slightly better crossed at 650Hz; and for theatre applications that’s probably where I will run it.

BMS’s can provide a clever HF – VHF passive crossover, it use two capacitors and one inductor providing 12dB low pass for the HF and 18dB for the VHF …. and the correct phase / time alignment. The crossover needs to be asymmetric because of the steep roll off the VHF has below 7kHz.

I suspect that in order to achieve its high efficiency BMS has minimised the diaphragm to phase plug clearance and is using a very high resonate frequency / low mass diaphragm. This however limits the low frequency capability and it rolls of sharply a little below 7KHz as noted above.

I was concerned because I need a lot more from the 4594 than I did with the double 10 that the passive HF – VHF crossover may not provide enough protection for the VHF… so I have run this box all active crossing at 6900Hz at about 54 dB per octave. The Lake FIR crossover allows me to do this and still sum flat though the crossover region, it also allows me to put some appropriate limiting for both the HF and VHF sections.

The advantage with the two-way HF – VHF design is its peak ability on complex waves forms. For example if you imagine a 1KHZ pulse (2.83 volts) with a 10KHz pulse (2.83 volts) imposed directly on top of it. The peak magnitude is 5.66 volts.

We can pass it through a crossover to get two waves 1 KHz & 10 KHz - 2.83 volts each. Into 8ohms this would be 1 watt each i.e 2 watts total. If we do this without the crossover then it’s 5.66 x 5.66 / 8 = 4 watts. This is peak power, the RMS continuous power or heating value remains the same – 2 watts.

Acoustically it’s more or less the same, but in terms of peak mechanical stress there is a significant amount more when one driver has to do both. In large compression drivers that are designed to go low, this can often result in none linear behaviour of the diaphragm. This is why I was using the 1480N with the Titanium Nitride Diaphragm previously – it’s much stiffer and operates as a piston to a much higher frequency. As a result it has less intermodulation distortion.

Turbosound have been doing this 2-way trick for years using a 6” cone diver/horn and VHF driver (EV DH3a) in their Flashlight and Floodlights and now in their Flex and Flash Line. They claim 6dB more usable output compared to a tradition compression driver with their combination.

In BMS case it’s a little trickier combining them in one driver and getting it all to work nicely in the same throat.

In the past when I have driven DH1A’s with extreme VHF levels I have neatly sheared the diaphragm off around where it attaches to the voice despite having a limiter. I once destroying 10 in one go; after that I always low passed them at about 15 KHz every time I needed them to go loud.

Bottom line … this little DIY goes loud and sounds great, Im yet to find anything better in this size and weight. If anyone can suggest a better driver for this application, I would love to try it.:nod:

... the suggestions so far have help me quite a bit with this design, thanks to everyone ... further suggestions a still very welcome.

 

[Ernie Montalvo]

Re: New DIY Mid High

Very nice setup....no reservations about using top components!

Are the BMS drivers in the same cost bracket as the 18 Sound NSD4015? The only price I found for it(18 Sound) was €600 on their official price list.

Curious how they would compare but I imagine differences at this level would be minimal. Interesting battle of compromises between domes and rings.