Studio Monitors (nearfield) - around the NeoPro5i - diyAudio
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Old 19th May 2007, 06:21 AM   #1
AdamZuf is offline AdamZuf  United Kingdom
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Default Studio Monitors (nearfield) - around the NeoPro5i

I'm no speaker builder, but I've been interested in the field for some time. I've built from other people's designs.
I'm a new sound engineer and I wish to have new nearfield monitors.
I've heard the lower ADAM (ANF-10, A7), Dynaudio BM5, PMC (DB1+,TB2+), which are the more regarded nearfiled monitors in my price range.

I felt that the ADAMs had the best transient reponse. They have a ribbon tweeter (some custom Eton, as far as I know, not available to us) and are crossed at about 1,8k. nice. A bit colored but they were the most alive and revealed the shape and texture of the soundstage best. I believe that this kind of what we call "revealing" is at least important as the details themselves - this I believe what maxes a mix that sound correct on this kind of speaker translate well on others.

The Dynaudios were more analytical, natural, yet not as dynamic and brutal in the way the translate the music I know. Very nice to listen to, but didn't have depth in the midrange.

The PMC sounds the best as a fun speaker, but they didn't differ different recordings very well, the soundstage tends to be made of their sonic signature everytime, to a certain degree. However, I was impressed by the bass of these things, as it was clearly tighter then the ADAMs, and I demonstrated these when set far away from the walls. They are line transmission design, and the port is on the back. I wonder how they will function when they are close to a rear wall.
Look at the design:
http://www.pmcloudspeaker.com/transmission.html

I can afford the lowest ADAM monitors, which use that ribbon tweet. They are very dynamic, and I think that the lower you go with the XO point, the better it is, if you don't reach driver stress or breakup. A studio monitor should be able to take high levels, but however, in my case, this is for the time when you got a pop, or a wrong gain setting- in other words, just for brief moments. I try not to monitor at high levels as this is not profesional.

So, we have a low XO point. I can't remember how different XOs designs affect off axis response, but I assume that we should aspire to even off axis response as much as possible. I still didn't get how wide should the response of a studio monitor be - of coarse you want to be able to move around the desk, however, too wide probably meens too much reflections from walls and ceiling. I also remember that MTMs have narrow horizontal dispersion - I don't know if that's good, because this only applies about the highs. If the ceiling is acousticaly treated, it meens that the first thing to die are the highs - so the reflected sound is very non linear. Probably better to go MT - in that regard at least. If the tweet is crossed low, maybe an MTM is more of an option because less the chance for comb filtering. Just an idea.

Anyway, wheather it's an MT or MTM, the woofer has to complement the tweeter with a very fast response. Smaller woofers are faster sounding (how is this called, damping factor or something?), would probably wise to define the size of the driver according to the room size, and requirements for the type of music mixed. Actually I'm fine with 40-45Hz, which is quite the low edge of most systems. I care more about dynamics and accuracy, as the woofers must be up to the tweeter, otherwise it was all for nothing, right? (-:

The only reasonably costing, commercial option I can see is the Fountek NeoPro5i. XO point recomended is 1500Hz, lower then the ADAM. Maybe it can go lower.
It's also very efficient at a 102dB/SPL average.
It is not a shielded tweeter and they actually warn about the high flux of it, but it might be worth it, and by the way, I use 2 screens but one obove the other, so the monitors will not be that close. It is a disadvantage though..

There's also the Mark & Daniel Maximus Monitor, which I haven't heard, and is highly regarded. Look:
http://www.mark-daniel.com/english_m/Proucts/P1_2.htm
It uses a big custom made ribbon which is crossed at 800Hz! wow, covering that 1K range with such a fast driver! Well, dream on, dream on...

Woofers - seems to me that good options for woofers that has been used in sucessful studio monitors are Scan-Speak (ProAc Studio 100, which I intend to listen to soon), Dynaudio and Vifa (used by Genelecs, some at least). But I heard that Fostex are revealing drivers, and are very efficient, which is very desirable, and opens up more options for amplifiers. I also seen them used in transmission line designs, IIRC..

I was impressed by the NTC transmission line and wondered how they made it sound right with such a small box like the DB1+ (it's a 5" woofer!). However, if such a designed would have been used, probably would be better to have the port on the front for a studio monitor application, for less reflecting bass from the wall, less dependancy. I base my last sentance on logic and not science, and actually many thing I've said in here, please correct me with my mistakes.

By the way, I think that biamping would be a good idea. maybe with a passive line level crossover. I just have to get the phase correct between my two amps..

MY GOAL? I can't design such a thing myself, honestly. I was hoping that since the DIY community is realy lacking in a realy good studio monitor, it would actually interest someone to design and have something that is available for many times the price, and maybe even make it better. Again, I don't know science, but having a low crossed ribbon (with its ultra low mass) and a small, fast driver with a very low mass and a narrow operating band which is complimented by transmission line to get the lows seems like the best of all worlds.

Adam
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Old 19th May 2007, 06:47 AM   #2
AdamZuf is offline AdamZuf  United Kingdom
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As a sub-subject of its own, how did PMC make such a small transmission line? Doesn't the length of it suppose to correlate with the wavelength of the frequency range missing?


In both the TB2+ and of the DB1+ the length of that path clearly does not relate to what's missing from the driver... So how does this work?
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Old 19th May 2007, 10:13 AM   #3
AdamZuf is offline AdamZuf  United Kingdom
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As I said, the woofer probably should be very fast, up to the tweeter.
I don't know much, but looking at Zaph's measurement of the W18EX001 it looks very good, considering the low crossover point for the NeoPro5i:
Click the image to open in full size.
Zaph also states that this woofer would enjoy a very low XO point - 1600Hz, which seems quite up to the tweeter!
He doesn't like ribbons, but it seems that my experience and so-called design goals might be worth a shot with the combination.
He recommends LR 4th order.
The recommended XO type for the NeoPro5i is 2nd order. Why is that? What would happen if crossed at 4th order?
(reminder: I'm thinking of active XO)

However, the W18EX001 is not a high sensitivity driver and that's too bad. Can high sensitivity drivers deliver equal or better timing? Zaph tested some Fostex drivers, but found the non linear distortion figures not optimal. However, considering that the speakers will not be used at high level, maybe meens improvement in that area?
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Old 19th May 2007, 01:22 PM   #4
AdamZuf is offline AdamZuf  United Kingdom
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Click the image to open in full size.
Here it's clear why the recommended XO frequency is 1500Hz.

Thi measurement is different then Zaphs, can anybody evaluate the timing difference between the 2 drivers in say, 1500 or 1600Hz?
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Old 19th May 2007, 07:07 PM   #5
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Quote:
Originally posted by AdamZuf
In both the TB2+ and of the DB1+ the length of that path clearly does not relate to what's missing from the driver.
Greets!

With a line length of ~4.92 ft it's plenty long enough to get to a usable 50 Hz. The larger cab's 40 Hz spec apparently has an effective line length typo.

GM
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Old 19th May 2007, 07:16 PM   #6
AdamZuf is offline AdamZuf  United Kingdom
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What's the formula for TL by which you can tell? Will it be the same if the port is on the front?

Is the Seas driver suitable for TL loading? (it's supposed to have low enough Qts, IIRC?)

I read different things about TLs: that they have peaks that add coloration, on the other hand offer extension of ported while sounding tight like sealed enclosures. Is there a method to control it, other then acoustic materials and a rigid box?

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Old 20th May 2007, 03:30 AM   #7
GM is offline GM  United States
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Greets!

Yes. This doesn't include any near boundry gain that will lower it further:
Fp = (13560"/4)/(path-length+(terminus radius*0.613))

When properly done, the classic TL mimics an IB in a much smaller, though still large cab, ergo whatever the driver's IB response is, the TL will be effectively identical down to Fs, where it will roll off at a slightly faster rate than the IB. So we can say that whatever the driver's Qts is, so will the IB's Qtc and the TL's Qp be for all intent and purpose. TLs can also be tuned for different applications that sound/perform considerably different than the classic alignment, hence the conflicting reviews. Driver position along the line and/or taper ratio has a major effect on the pipe's smoothness also.

Contrary to what some folks seem to believe, any driver can be TL loaded with good results, it's just a matter of choosing the right driver for the app. From what you've posted, it seems to me you need to just buy what you like since without complete tech data there's no way for me or anyone else to 'clone' it. Anyway, having been 'weaned' on large, dynamic Altec, etc., horn loaded studio monitors I'm the wrong person to ask about using a dinky little bookshelf speaker for this app.

That said, if I were going to make a relatively small two way TL nearfield monitor with a ribbon, Jim Griffin's Jordan/Aurum Cantus would be a good starting point.

GM
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Old 20th May 2007, 05:11 AM   #8
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GM,

THANKS for saying it loud and clear - the idea "you need very specialized drivers for a TL" is as stupid as "any driver will perfectly drive any horn".

That said - I can't log into the FRD forum at the moment, but I'd very much like to get our misunderstanding out of our lives.

Pit
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Old 20th May 2007, 05:30 AM   #9
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Quote:
Originally posted by Pit Hinder
That said - I can't log into the FRD forum at the moment, but I'd very much like to get our misunderstanding out of our lives.
Greets!

????

GM
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Old 20th May 2007, 05:36 AM   #10
AdamZuf is offline AdamZuf  United Kingdom
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GM
In that formula, there's no importance to the radius of the path itself, and if I relate these correctly, indeed in the PMC the "terminus radius" is as wide as the path itself.
Click the image to open in full size.

However, You can see that the drivers takes considerable volume from the TL path, and the cross section width is higher to allow space. This corelates to the formula, in which it doesn't matter.
Am I right about this?

If so, why are they the first ones to imply a path with a cross section as wide as the port (for the most part of it) in a design? What's the advantage of other TL shapes?

Quote:
From what you've posted, it seems to me you need to just buy what you like since without complete tech data there's no way for me or anyone else to 'clone' it.
I don't wish to clone it since I'll use a different driver. I just want to understand the idea behind it, so there will be no need to buy a speaker I can hardly afford, and even if so, I'll have no money to make a new one.

Thanks
Adam
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