top spec nearfield monitor with extended LF response

[legezer]

I am looking to build a set of nearfields. I have some knowledge of acoustics (I have measured and treated several rooms, including building tuned Helmhotz panels for one) but only a little knowledge of speaker design. As a little knowledge can be a terrible thing I will be getting Wilmslow audio to do the specifics of the design.
My room is only 12' (3 m 66cm) x 8' 3" (2m 50cm)
currently I have a good amount of broadband absorbtion and diffusion, but I am here long term, so I am going to build tuned panels soonish.
speakers are either side of my workstation mounted vertically on stands, 2ft(60cm) from the back wall and 1ft(30 cm) from the side walls. so the tweeters are 4'4" apart and thats the distance from ear to tweeter when I'm in mixing position.

I know I want all my drivers in vertical alignment, I do not want duplicate drivers and I do not want a separate sub

I do not require great volume at all but need the bass still to be there at low volumes

I am leaning towards a 3 way design using up to a 3" ATC dome to cover the vocal range in a tried and tested combination with a great soft dome tweeter.

But I really want to get the bass extension down to 30something hz +-2db. The best speaker I have heard for really delivering subs clearly from a small box to a close listening position (and it was in a small very well treated room) was the PMC AML1, which is a tiny transmission line apparently a scaled down version of that in the LB1. But I haven't been able to find any designs for small transmission lines.

I could afford the box to be significantly bigger than the AML, and If it were possible to avoid a port or TL it seems to me desireable (I'm into simplicity wherever possible)- I had been under the impression that it wouldn't be possible to get the bass response I am after with a sealed box, but the guzauski-swist GS-3a claims +-2db down to 28hz from 2 cubic foot sealed enclosure. I haven't been able to find any info on the 12" Dayton aluminium driver it uses, but must it sacrifice sensitivity for this response as the system is driven by 4k of amps!
The GS-3a is right at the cusp of what I could fit in size-wise at 24"(60cm) high by 14.4" (37cm) by 15.5" (40cm)deep (in its vertical alignment) but a 12" might be overdoing it a bit for the room, so- finally getting to specific questions-

is there a 10" driver that I could put into a correspondingly smaller sealed enclosure and still get down smoothly into the 30s? or would a 12" be the way to go(remembering I do not need to go very loud, and I'd rather not have to run a massive amp)

do you have any materials/techniques/designs on how to as near as possible eliminate resonances in a sealed enclosure?

are there any issues with treating the construction as 2 separate boxes tailored to the drivers they house ? any tips for how then to unify them as 1 unit while keeping them as de-coupled as possible…
any other advice/links/anything that can help me succeed in this quest.

many thanks in advance

 

[spladski]

Hi, I have experience with the 3" ATC dome. It will need to crossover at about 1KHz with the bass. Therefore you will need an agile bass driver which to a certain extent conflicts with deep bass. You should not rule out a small powered sub operating from 50Hz down.

From the size of your room wide dispersion dome may not be the best option even if it is a low distortion driver. Remember it is only low distortion over its pass band which is narrow. You will need more room treatment to defeat the wide dispersion hence creating a self defeating exercise. Study the JBL 4312M. Vertical alignment will mean you will need to sit further away for proper integration.

 

[spladski]

The task you are about to undertake is quite difficult for a novice. You will need to do much research.
DIY Loudspeaker Projects Troels Gravesen

 

[Charles Darwin]

From everything I read about the ATC 3" dome it works best when crossed in at 380Hz.
This is what ATC themselves do and they should know their own driver rather well.


The Barefoot Sound Micromain 35 does 39-20 000Hz +- 1.5dB out of a 19L box.
Might be worth a look just for inspirations sake if nothing else.

 

[legezer]

From everything I read about the ATC 3" dome it works best when crossed in at 380Hz.
This is what ATC themselves do and they should know their own driver rather well.
The Barefoot Sound Micromain 35 does 39-20 000Hz +- 1.5dB out of a 19L box.
Might be worth a look just for inspirations sake if nothing else.

Thanks for the info! yes I was thinking it would be in the 300s somewhere. I haven't heard the barefoot stuff, but I am very much inclined towards keeping it simple and having 2 or 3 drivers pointing at me in alignment.

 

[legezer]

The task you are about to undertake is quite difficult for a novice. You will need to do much research.
DIY Loudspeaker Projects Troels Gravesen

Thanks for the info!
I have been looking on here, but the smaller TL designs don't seem to have the LF extension, and they don't seem to have any infinate baffle designs. I am definitely not taking this lightly. I have a friend who designs (and I mean really develops) PA speakers, and he could model it for me, but he's not gonna know much about the drivers or designs for small enclosures

 

[spladski]

Crossover frequency for the ATC 3" depends on implementation. 380Hz is OK with 4th order filters. This is what ATC use with active crossovers.

 

[legezer]

From the size of your room wide dispersion dome may not be the best option even if it is a low distortion driver. Remember it is only low distortion over its pass band which is narrow. You will need more room treatment to defeat the wide dispersion hence creating a self defeating exercise. Study the JBL 4312M. Vertical alignment will mean you will need to sit further away for proper integration.

thanks this could be very useful advice. I did say up to a 3" as I did think there may be reasons why smaller could be more suitable, and here's one.

re your last point maybe this is an argument for going 2-way? many of the speakers that would excel at this distance (pmc AML1 or 2, Meyer HD1) are 2-way.

 

[spladski]

You haven't stated which is your preference. Active or passive. TL designs do not automatically confer more bass. It is a volume related thing. Read Stereophile review of small TL from PMC.

 

[legezer]

You haven't stated which is your preference. Active or passive. TL designs do not automatically confer more bass. It is a volume related thing. Read Stereophile review of small TL from PMC.

Passive. I'd like to be able to continue using my Quad 405mk2 but realise I may have to match something more powerful (even though I don't need high levels)
depending on the design.
I want to keep the crossover as simple as possible so I can spend the money on quality components rather than lots of them, so I need to select drivers that naturally complement each other

Thanks, I will have a look at that article. I'm leaning towards a sealed box but don't know all the variables for getting the optimum performance 'down there'. At some point I will take the idea to wilmslow...but the more knowledge I can get before that point the better.

 

[spladski]

It is a bit difficult to advise you because you are after a custom design. This means that someone is going to have to design a crossover. That person is unlikely to be you. So unless you can get someone who can physically guide you, you have a problem. Wilmslow would be able to offer you stock designs that match drivers. Someone might be prepared to guide you long distance but it would be painfully slow.

If you go down the active route you can do it all yourself and choose whatever drivers you like. This would mean buying a second amp for a 2-way design. The Quad 405 is a perfectly good amp and I know of studio engineers who use it. The active crossover could be a Behringer DCX2496. Because you have measuring equipment, the whole process can be brought under your control.

I have used a DCX2496 and it is an amazing piece of kit. A friend of mine uses one in a biamp situation with Altec 604s which used to be a studio staple in the old days.

 

[legezer]

It is a bit difficult to advise you because you are after a custom design. This means that someone is going to have to design a crossover. That person is unlikely to be you. So unless you can get someone who can physically guide you, you have a problem. Wilmslow would be able to offer you stock designs that match drivers. Someone might be prepared to guide you long distance but it would be painfully slow.

If you go down the active route you can do it all yourself and choose whatever drivers you like. This would mean buying a second amp for a 2-way design. The Quad 405 is a perfectly good amp and I know of studio engineers who use it. The active crossover could be a Behringer DCX2496. Because you have measuring equipment, the whole process can be brought under your control.

I have used a DCX2496 and it is an amazing piece of kit. A friend of mine uses one in a biamp situation with Altec 604s which used to be a studio staple in the old days.

Hmm interesting. Iam leaning more towards a 2 way design anyway, and actually have 2 Quads. the only thing I don't like about the amps is the unbalanced inputs.
I definitely want to keep the signal analogue though between the mixer and the amp.

 

[Inductor]

...The GS-3a is right at the cusp of what I could fit in size-wise at 24"(60cm) high by 14.4" (37cm) by 15.5" (40cm)deep (in its vertical alignment) but a 12" might be overdoing it a bit for the room, so- finally...

Just an idea. Ciare H03.4 SISTEMA 3-Way.
CIARE HW 203, VB = 47.9 L, FB = 29.2 Hz, 90.3 dB2.83Vm.
F3=42 Hz, F6=31 Hz, F12=22 Hz (05.2012/Inductor)
Ciare HW 203 - 8" high efficiency woofer
Ciare HM 500 - 91 dB Mid Dome
Ciare HT 262 - Tweeter
Ciare H03.4 3 System Project
CIARE PA Loudspeakers - Lean Business - UK

 

[legezer]

But If I biamp and want to keep it in the analogue domain, I guess that means I am back to needing a custom crossover...

 

[RockLeeEV]

KEF Q900 + Usher 1001B sealed, with a linkwitz transform to extend response

Honestly, without measurement equipment and experience, I don't see OP making the reference class speaker s/he desires. The crossover is half the speaker, and especially so in a 3-way.

Another consideration

CSS SDX10 + SEOS-12 waveguide + DIY Sound Group compression tweeter

At least this way you keep it two-way.

But If I biamp and want to keep it in the analogue domain, I guess that means I am back to needing a custom crossover...

And what is the benefit of keeping it in the analogue domain? Don't tell me you think one extra ADC/DAC conversion is going to hurt SQ.

 

[burgunder]

What about this one http://www.diyaudio.com/forums/multi-way/193689-build-thread-ardor-point-source-monitor.html

 

[legezer]

KEF Q900 + Usher 1001B sealed, with a linkwitz transform to extend response

Honestly, without measurement equipment and experience, I don't see OP making the reference class speaker s/he desires. The crossover is half the speaker, and especially so in a 3-way.

Another consideration

CSS SDX10 + SEOS-12 waveguide + DIY Sound Group compression tweeter

At least this way you keep it two-way.



And what is the benefit of keeping it in the analogue domain? Don't tell me you think one extra ADC/DAC conversion is going to hurt SQ.

Thank you I will look into those 2 ideas. I can understand why you think it won't happen, and you may end up being right. I did not realise Wilmslow wouldn't be able to provide me with the correct crossover for a custom design.
I am clear now 2 way is the way to go.

Yes I am afraid I was able to A/B loopback through some pretty expensive converters with direct signal some years ago and was quite shocked, I am quite attached to the idea of the signal from my analogue mixer directly driving the amp. But I could take AES or spdif out of my master recorder into a processor. I have only ever used them for PA systems, don't know much about 2 way ones or the kind of programming and testing that would be required to get the design working at it's best. But I do have an extremely knowledgeable friend who's number I need to track down

 

[RockLeeEV]

I am clear now 2 way is the way to go.

Great. Here's another one I'm thinking:

Linkwitz Transform + Seas W26FX001 + CSS LD25X + Dave Pellegrine's custom waveguide for it to extend response down to ~950hz

 

[boris81]

What about this one http://www.diyaudio.com/forums/multi-way/193689-build-thread-ardor-point-source-monitor.html

I'm starting to doubt the importance of designing to eliminate the vertical lobing at the crossover. I don't think I like the Vifa NE19VTA-04 tweeter anymore so a larger one with a higher crossover might be the better choice.

With a Linkwitz Transform the woofer produces decent bass in that smallish box but 30Hz will be pushing it. You do need at least a high excursion 10".

 

[RockLeeEV]

I'm starting to doubt the importance of designing to eliminate the vertical lobing at the crossover. I don't think I like the Vifa NE19VTA-04 tweeter anymore so a larger one with a higher crossover might be the better choice.

That's a nice tweeter IMO, but that crossover point seems an octave or two too low for it....It seems to me that the FMD from that crossover frequency would cause sibilance higher up.

The same CSS LD25X, with the flange removed option, would be a very interesting option for your design.