Nearfield design considerations....

[Maximiliano]

Can someone explain to me what is required by nearfield speakers? For example, what would differentiate the default L18 design from its nearfield version? AFAIK, it must be a reduced BSC version. Am I correct? If so, generally how much BSC for nearfield monitors?

Max

P.S. Sorry for the off-topic post. But I just need a quick answer

[vcmc]

Max, nearfields need a flatter on-axis response than mid- or farfield monitors. They're intended to, as much as possible, take the reverberant field out of the equation (though their ability do do that is called into question, particularly in smaller rooms, or as stated above, in close proximity to walls/corners etc...)

Zaph, count me in for the alternate crossover info as well. Thanks!

[Maximiliano]

Max, nearfields need a flatter on-axis response than mid- or farfield monitors.

The L18 is already pretty flat at 1 m (http://www.zaphaudio.com/audio-speak...d-response.gif). Is nearfield supposed to be shorter than 1 m? What happens if we sit close to speakers?

Max

[peter_m]

What happens if we sit close to speakers?
Max

One possibility: http://www.bohemianscientist.org/ima...eadexplode.jpg

[jkrutke]

I'll post that L18 near field design here as soon as I get some time. I'll also discuss how I arrived at it. I hope to have some time tonight before I take off.

[jeff_free69]

One possibility: http://www.bohemianscientist.org/ima...eadexplode.jpg

must be using Mackies

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typically you're within 3ft when leaning into the mixer, or maybe 4 if you lean back. So a large sweetspot and non-fatiguing mid/hi's are also a factor. But you want the sound honest, not necessarily "pretty". Any exagerations and non-linearites in the sound will cause you to compensate in the opposite direction so when the mix gets out into the real world, it will not translate well (eg if the hi's are very aggresive, you will mix them down, but it will sound dull on other systems)

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I 'd greatly appreciate those nearfield specs, if that included some specific brands/parts recommendations even better.
- thanks!

[jeff_free69]

BTW - the L18 aluminum drivers will have a big visual wow factor for clients, if this turns out to be the way to go for me !

[jkrutke]

L18 / 27TBFCG Studio monitor

Unfortunately, digging through all my ancient design stuff, this is all I have on it. If I recall, the couple guys who built it set them on a console ledge facing the listening chair, approximate listening distance of 1m. Ports should go on the front - this is mainly because ports on the back place them further away from the listener and effectively down in level. One guy did 2 triangular ports under the woofer. (of his own size and length calcs)

The crossover point looks like 1650, and the design is effectively 3dB BSC. The lower crossover point is probably a tiny bit cleaner than the default system at the expense of tweeter power handling which is not needed nearfield anyway. Judging by the topology, the tiny cap across the primary inductor will need to be that exact value. If you look around, you should be able to find one in that size.

If anyone builds it, let me know how it serves your purposes. I only have the feedback of a couple people on this. The feedback was positive but I'm hesitant to trust anyone's ears but my own. I'm not too familiar with the needs of a recording studio and this was just my estimate of what might sound good there.

[Maximiliano]

Hmm... Looks like simply a reduced BSC version with a lower xover frequency. I think I was correct.

Max

[jeff_free69]

Thanks! i understand you can't endorse something you never actually heard. But I assume you don't see anything too off-the-wall here...

I reread your original L18 post and you mentioned it was very good though not best you could do back then. How would you compare that to the new SR71 design?

The speaker will be used on a stand , 2-3 feet from the side and back walls (heavily treated w/ bass traps etc). But the mix desk will directly in front, about 10 inches (?) lower. For serious mixing I lay 4" foam wedges on it. (Its amazing how many people obsess over their mix but don't realize how much the desk reflections affect it!

So I started scoping out the parts on this mod. Its been over 10 years since my last big DIY project, so I'm not really up on the current hot brands and sources and would appreciate any comments and guidance. Ballpark is $160 -180 each for XO and drivers. Here's what I found so far:


L0 2.0 mH
Mad 15awg steel $10.30
Jantzen 2.0mH 15awg Air Core Inductor (.5 DCR) $24.12
2.0mH 14 AWG Perfect Layer (.31 DCR) $23.34

L6 0.5 mH
Mad 19awg $ 3.35
0.50mH 18 AWG Perfect Layer (DCR: .32) $6.92

C2 0.22 uF
Clarity PX $2.15
Clarity SA $3.75
Dayton PMPC-0.22 $1.35

C3 16.0 uF (15+1)
Clarity PX $9.20 + 2.15
SA $17.85 + 4.40
Dayton PMPC-15 $9.72 + Dayton PMPC-1.0 $1.91

C5 10.0 uF
Clarity PX $5.90
SA $14.10
Dayton PMPC-10 $6.97

Seas Tweeter 27TBFC/G (H1212) $ 37.60
Seas L18RNX/P (H1224) 7" Aluminum Cone $ 75.05

1) Madisound doesn't specify DCR for the inductors, so I guess I should assume they are higher than recommended (Is a lower value ok? - i didn't find an exact match)

2) Is Clarity SA worth the cost over PX ? or Dayton?


THanks again!

[Maximiliano]

You can find DCR specs of Madisound inductors here:

http://www.madisound.com/about/inductors.php

Max

[Nemophyle]

I reread your original L18 post and you mentioned it was very good though not best you could do back then. How would you compare that to the new SR71 design?

i think you're taking zaph's original sentence a little too seriously, here is the sentence

This doesn't represent the best I can do... It represents the point where I stop the design, sit back and enjoy the music.

mind the smiley at the end

In zaph's mentality aswell as in most of the speakers guys here (sorry for talking in your name, correct me if i'm wrong :B ) a speaker is never nor perfect nor finished, the fact that zaph mentions that at the end of the L18 article implies nothing about L18 performance, but more about zaph's nitpicking mentality i'd say

[jkrutke]

1) Madisound doesn't specify DCR for the inductors, so I guess I should assume they are higher than recommended (Is a lower value ok? - i didn't find an exact match)

2) Is Clarity SA worth the cost over PX ? or Dayton?

The answer to that will be different for various people. I personally use Bennic Poly caps all around because I am unable to hear a difference with more expensive caps. Don't worry about DCR values too much, just get kind of close if you can. Keep the woofer DCR relatively low.

In zaph's mentality aswell as in most of the speakers guys here (sorry for talking in your name, correct me if i'm wrong :B ) a speaker is never nor perfect nor finished, the fact that zaph mentions that at the end of the L18 article implies nothing about L18 performance, but more about zaph's nitpicking mentality I'd say

True, most of the designs I do never feel like they are finished. I may be happy enough to publish a design but inevitably I start wondering if I should have done if differently. I might have previously mentioned crossing over lower to avoid the 5th order harmonic, but that of course lessens the power handling of the tweeter. I consider the original L18 design a good set of tradeoffs.

[jeff_free69]

True, most of the designs I do never feel like they are finished. I may be happy enough to publish a design but inevitably I start wondering if I should have done if differently. ..I consider the original L18 design a good set of tradeoffs.

That's really what i was looking for. Hindsight always gives perspective. From a musician's point of view, I know what its like to spend a lot of time tweaking something, like a mix. When it gets to that 99% level and you're in the middle of it making changes, you recognize that something is different, but you may not be sure if its better. Knowing when its done is the hardest question!

When I had more time i used to experiment with various drivers and crossovers, but at this point I want to just sit back and listen to the music ASAP, as John said.

Thanks for your help

[kenrinc]

I went ahead and built these using the reduced BSC version of the crossover. I'm using them as nearfields in a bedroom studio with custom console. They sit up above on ledges decoupled with whispermat. I subsequently built the original crossover just because one, I wanted to see how different the lower frequencies were and two I had the parts on hand. My setup has them about 6" out from the rear wall with ports out front. I also went with PE .75 enclosure which obviously affects how they sound. After messing with both xovers for a few months I like the reduced BSC better for my application (obviously due to room setup). The imaging is excellent in both but the reduced BSC version is just simply incredible. So far I haven't been able to make any music because all I do is listen to other peoples music :-)

Ken

[jeff_free69]

So far I haven't been able to make any music because all I do is listen to other peoples music :-)

Ken

I did the same thing going thru hundreds of CD's cause I loved the new speakers so much in my studio. (Its been a while - but you're talking about the Sr-71's, right ?)
I ultimately ended up doing a relatively minor tweak to the original BSC design to slightly raise the tweeter level cause i found the reduced BSC suggestions too aggressive in my application.

Actually I have them "loaned out" to the living room now until I finish building another set of smaller speakers for the new HT. They still sound very good there even though they're close to the wall.

[kenrinc]

Jeff,

No actually this is the Zaph L18/27TBFCG unit (metal seas). SR71 uses E18. I'd like to adjust the low end of the reduced BSC as well. Just a tad. I'm guessing a db or so. From what I can see in my sweeps of the room it seems the low end is still way lower than the mid and high but I need to perfect my mic placement before you can quote me on that...

Ken