"Mynamid" - newb 3-way design

"Mynamid" - newb 3-way design

For some odd reason I decided to design my own speakers. I have some experience with wordworking like production in college theater, but nothing as involved as this (I'm not am expert at all!). I have a lot of experience working with audio so these speakers need to be critical.

I'm a grad student with a focus on music composition. Before we get our masters degree we have to have a semi-pro CD prepared. I do a lot of audio engineering so I'm pretty much a DIYer.

Here are the sketches & dimensions, and a cardboard mock-up, of what I call the "Mynamid":
http://picasaweb.google.com/ascottk/MynamidSpeakerDesign

Inspired by other pyramidal designs & some time-aligned designs.

If you care to comment about the enclosure, please do so, but I'm past the point of no return to do any major modifications to it :xeye: Maybe I'll be flexible about the drivers since I haven't cut the holes yet. I was thinking about these drivers & components:

Vifa D26NC55
[IMGDEAD]http://www.madisound.com/catalog/images/madisound/product/D26NC55.jpg[/IMGDEAD]
http://www.madisound.com/catalog/product_info.php?cPath=45_229_270_324&products_id=1078
Good reviews about this one at ZaphAudio http://www.zaphaudio.com/tweetermishmash/

Dayton RS52AN-8 2" Dome Midrange
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=285-020
[IMGDEAD]http://www.partsexpress.com/images/285-020m.jpg[/IMGDEAD]

Dayton XO3W-500/4K 3-Way Crossover 500/4,000 Hz (I haven't decided yet)
[IMGDEAD]http://www.partsexpress.com/images/260-150m.jpg[/IMGDEAD]
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-152

The enclosure will be about 21 liters I guess & I may be wrong since I'm new to this.

Anyway, I need help choosing components! Once again, here's the link to the "Mynamid" design:
http://picasaweb.google.com/ascottk/MynamidSpeakerDesign
img011.jpg
img012.jpg

Mynamid_back.jpg
Mynamid_Front.jpg
 
Oh man! One of the biggest challenge I can see in what you are trying to do is in the crossovers. I am relatively new to this but I can tell you that premade XO's will not work optimally. Sure you will get sound but it will not be good even with expensive drivers. I have proven this by the hard way-making the same mistake that you are about to make if you don't change course. Build a proven design- is the recommendation at least untill you learn more about speaker building then you can tackle or reconsider building a 3-way.
Pick a design in these sites. Read and learn too!

zaphaudio.com
rjbaudio.com
partsexpress.com
http://www.geocities.com/cc00541/index.html

Theres more but people here can point you to them.
 
idaho said:
Oh man! One of the biggest challenge I can see in what you are trying to do is in the crossovers.

zaphaudio.com
rjbaudio.com
partsexpress.com
http://www.geocities.com/cc00541/index.html

Theres more but people here can point you to them.

You're right and thanks for the links. I might stick with my existing drivers:
Yamaha NS-A637
nsa637.gif

http://www.yamaha.com/yec/products/productdetail.html?CNTID=200443&CTID=50029000

  • Three-Way Acoustic Suspension, Magnetically Shielded Bookshelf
  • Woofer = 8 in. Hi-polymer Coated Cone
  • Midrange = 4 in. Cone
  • Tweeter = 3/4 in. Dome, Ferro-fluid cooled
  • Input Power Nominal = 70W, Music Input = 140W
  • Frequency Range 90 to 20,000 Hz +/-3 dB

I don't know how accurate the specs are for the original replacements:
Yamaha NS-5 NS5 NS-A636 NSA636 NS-A637 NSA637 Replacement Speaker / Speakers drivers for sale. Used Vintage Yamaha drivers woofer / woofers, mids midrange / midranges tweeter tweeters crossover cross over crossovers overs, cabinets & grills for Yamah

The mid-bass (above 300 Hz?) upwards translate well with my mixes and masters but I always have to guess how the lower bass is doing even with a sub. I'm definitely not crazy about the mylar dome tweeter on these. I don't like the enclosure either.
_____________

When I have some money I'll buy some better drivers (need to find a midrange with a 3 3/4" cutout), and either have someone build new xovers or design my own with some help with this:
http://www.lalena.com/Audio/Calculator/APCXOver/

& there's someone in Oregon who builds custom xovers:
http://www.chokes.com/custom_crossovers.html
_____________

Anyone have suggestions for drivers aside from my own? Here's the requirements:
  • tweeter: 2" cutout (3 - 3 3/4" diameter faceplate), 8 ohms, sensitivity around 90 dB, fairly flat response to or above 20 kHz,
  • midrange: 3 - 3 3/4"" cutout (around 5" diameter faceplate), 8 ohms, sensitivity around 90 dB, accurate, works well with above tweeter and woofer
  • woofer: I have a few woofers I can probably use that need testing. 8" woofers. 8 ohms. accurate for a 21 liter enclosure.
    _____________
    Since I can't edit my posts, here's the front view of my enclosure (cardboard mock-up and the woodworking is nearly done!):
    Mynamid_Front.jpg

    I designed it this way because most time-aligned speakers are pointed upwards or stepped. I need the tweeter to be pointing at listening position so it's not angled.

    I'll probably move the midrange closer to the tweeter.
 
You have a nice midrange and tweeter picked out there. Both really good in the distortion area. I have read some good reviews of both. For the woofer, you should consider the Usher 8" 8955A. It has the low-distortion motor found in the 7" woofer that is reviewed on Zaph's website.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-618


Don't forget you have to include some level of baffle step correction, which means you may be hard press to get to 90 dB/SPL.

Another option would be two Dayton RS 8" 4-ohm, it will get you 8-ohm total if you wire in series and more surface area for that deep bass.

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=295-376
 
69stingray said:
You have a nice midrange and tweeter picked out there. Both really good in the distortion area. I have read some good reviews of both. For the woofer, you should consider the Usher 8" 8955A. It has the low-distortion motor found in the 7" woofer that is reviewed on Zaph's website.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-618


Don't forget you have to include some level of baffle step correction, which means you may be hard press to get to 90 dB/SPL.

Another option would be two Dayton RS 8" 4-ohm, it will get you 8-ohm total if you wire in series and more surface area for that deep bass.

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=295-376
Thanks! Okay, suppose I bought a Dayton RS225S-8 (8 ohm) with a 88 dB sensitivity. I need to bring down the tweeter & midrange 3 dB with l-pad circuits?

Without baffle step correction (need more research on that), here's what I came up with (1st order, 500/4000 Hz).
 

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ASCOTTK-

I would recommend picking some drivers and first doing a design using the free FRC tools. This is a good way to do a design "on paper".

Here is a quick outline:

1. Trace the mfg. freq. curves and impedance curves.
2. Use Unibox to determine the low-freq. output.
3. Use BSC to determine the baffle loss response. (By the way, you loss -6 dB when the freq. wavelength is wider then your baffle - in simple terms).
4. Use Freq. Response Combiner to combine all of the freq's into one.
5. Extract the proper phase.
6. Then use the crossover designer to design a crossover. (You will need a more complicated X-Over the 1st order I think).

When you get to item #6, people can help and point you in the correct direction. And give some guideness on the necessary steps. I am no crossover pro by any means. When you get to #6, post you results (w/o crossover) and then we can stay adding X-Over parts to see what is needed.

Here is a better step-by-step procedure for using the tools:

http://www.rjbaudio.com/Audiofiles/FRDtools.html
 
Thanks for the link!

Unfortunately the FRC spreadsheet didn't work too well for me so I used the method here:
http://www.angelfire.com/electronic/loudspeaker/projects/speakerworkshop.html

Here's the frequency response I have in Speaker Workshop so far:
[IMGDEAD]http://img407.imageshack.us/img407/4138/mynamidfreqkg9.th.jpg[/IMGDEAD]

& here's the XOver:
[IMGDEAD]http://img89.imageshack.us/img89/3774/mynamidxoveroq3.th.jpg[/IMGDEAD]

I chose the RS225S-8 for the woofer. There's no ported box model combined with the woofer's fequencies.

Is the crossover too complicated?
 

Hezz

Member
2002-12-22 6:52 am
Utah
ascottk,

You have a nice little cabinet design. But I have to ask if these are going to used in the near field as near field monitors. If so, may I make a few suggestions. With a few good design ideas you can make these into a pretty decent pair of mixing monitors.

First, the midrange is the most important driver in this so don't use a dome midrange like the dayton 2 inch dome.

Second as you have been informed the canned Dayton crossover will not work well.

This is what I would do. The cabinet shape is pretty good for spreading out internal standing waves and modes. Use a 5.25 or 6.5 inch high quality mid/bass driver so that it's edges are very close to the 8 inch woofer and the tweeter frame. Since you will be listening at close range the drivers need to be mounted as close together as possible. This is very important for a mixing monitor since the sound from the different drivers need to blend together well at close range. This means that the mid/bass driver needs to be very smooth with no bad spikes or breakups at higher frequencies. The Silverflute Wool cone drivers may work well here and they are inexpensive. Stick with a paper or polycone mid/bass since they are easier to integrate with first order crossovers.



Create an internal shelf that physically divides the woofer and midrange into two separate cabinet spaces. It will act as a brace and to separate the two spaces. Use aperiodic loading for the midrange to get more accurate pitch definition which can approximate an infinite baffle loading in a small cabinet space. Unless the space is big enough for a critical Q sealed loading I would go with aperiodic for the mid/bass loading.

For the 8 inch, you can use aperiodic and sacrifice some bass extension but have better sounding and more tonally accurate bass or go with a bass reflex loading. I would not recommend sealed for the bass for a mixing monitor unless it is critical Q.

Try to find an 8 inch woofer that can get good strong bass in a smallish space. The best one I know of is a HI VI 8.8 in needs about 1 cubic foot and goes down low and strong in that space.

Because you are new to crossover design keep the crossover points out of the fundamental music frequencies. So let the midrange driver cover about 80Hz to 2500Hz where it crosses over to the tweeter. Try to use first order crossovers but no higher than second order since you will likely be listening at close range. This will make mixing a lot easier as there will not be any phase related sound problems in the most important music fundamental range.

Also, once you have the right drivers and cabinet selected and designed Madisound can design a custom Leap crossover for you for about 45 dollars. If you don't want to test and measure the speakers yourself. While not perfect, a Leap design crossover from Madisound would destroy a canned Dayton crossover in sound quality.
 
The best piece of advise I can give is to build a proven design, this is too complicated for a first DIY project.

However, designing stuff is still fun, so some comments....

Your crossover does not address the cone breakup of the RS52. Try adding an inductor after, and in series with, the lowpass capacitor. Make it a really small value, then adjust it down, until you notch out the 12khz resonance peak.

How are your reverse nulls? If you flip the polarity on the RS52, do both the highpass and lowpass crossovers give you a nice null at the listening axis?

What does your vertical polar response look like?

Have you factored baffle diffraction effects into your design?

Dan
 
Hezz said:
ascottk,

You have a nice little cabinet design. But I have to ask if these are going to used in the near field as near field monitors. If so, may I make a few suggestions. With a few good design ideas you can make these into a pretty decent pair of mixing monitors.

Yes, nearfield & hopefully mid-field in the future (I need more room!)

First, the midrange is the most important driver in this so don't use a dome midrange like the dayton 2 inch dome.
They are theoretically a pain to work with so far.
Second as you have been informed the canned Dayton crossover will not work well.
I actually tried one in Speaker Workshop & it didn't work well at all.

This is what I would do. The cabinet shape is pretty good for spreading out internal standing waves and modes. Use a 5.25 or 6.5 inch high quality mid/bass driver so that it's edges are very close to the 8 inch woofer and the tweeter frame. Since you will be listening at close range the drivers need to be mounted as close together as possible. This is very important for a mixing monitor since the sound from the different drivers need to blend together well at close range. This means that the mid/bass driver needs to be very smooth with no bad spikes or breakups at higher frequencies. The Silverflute Wool cone drivers may work well here and they are inexpensive. Stick with a paper or polycone mid/bass since they are easier to integrate with first order crossovers.
I might just use the Yamaha's mids. I still have time to think about it though. Unless I want to recarve the mid's hole, I need to stick with a mid with a 3 3/4" cutout.

Create an internal shelf that physically divides the woofer and midrange into two separate cabinet spaces. It will act as a brace and to separate the two spaces. Use aperiodic loading for the midrange to get more accurate pitch definition which can approximate an infinite baffle loading in a small cabinet space. Unless the space is big enough for a critical Q sealed loading I would go with aperiodic for the mid/bass loading.
Too late for a shelf as you'll see at the bottom of this post . . . And what do you mean by aperiodic? I haven't come across that in my research yet.

For the 8 inch, you can use aperiodic and sacrifice some bass extension but have better sounding and more tonally accurate bass or go with a bass reflex loading. I would not recommend sealed for the bass for a mixing monitor unless it is critical Q.

Try to find an 8 inch woofer that can get good strong bass in a smallish space. The best one I know of is a HI VI 8.8 in needs about 1 cubic foot and goes down low and strong in that space.
Thanks for the suggestions! & a bass port is already in.
Because you are new to crossover design keep the crossover points out of the fundamental music frequencies. So let the midrange driver cover about 80Hz to 2500Hz where it crosses over to the tweeter. Try to use first order crossovers but no higher than second order since you will likely be listening at close range. This will make mixing a lot easier as there will not be any phase related sound problems in the most important music fundamental range.

Also, once you have the right drivers and cabinet selected and designed Madisound can design a custom Leap crossover for you for about 45 dollars. If you don't want to test and measure the speakers yourself. While not perfect, a Leap design crossover from Madisound would destroy a canned Dayton crossover in sound quality.
Thanks again.

___________________
owdi said:
The best piece of advise I can give is to build a proven design, this is too complicated for a first DIY project.

However, designing stuff is still fun, so some comments....

I didn't like any of the designs I saw on the web so I came up with this & I went ahead with this idea or I would regret not building my own speakers! I'm actually tired of looking at the same ol' speaker enclosure designs . . .
Your crossover does not address the cone breakup of the RS52. Try adding an inductor after, and in series with, the lowpass capacitor. Make it a really small value, then adjust it down, until you notch out the 12khz resonance peak.
The inductors theoretically didn't work.

How are your reverse nulls? If you flip the polarity on the RS52, do both the highpass and lowpass crossovers give you a nice null at the listening axis?
There's was a lot of dips at the xover points in the Speaker Workshop sim when the mid was not flipped.

What does your vertical polar response look like?
I have no idea how to simulate that or test it.

Have you factored baffle diffraction effects into your design?
Yep.

Anyway, I tested my enclosure a few days ago with duct tape for a temporary seal and I was fairly pleased (note the EnABL patterns on the drivers . . . I didn't do a very good job putting those on):
[IMGDEAD]http://img205.imageshack.us/img205/9630/sany0052on5.th.jpg[/IMGDEAD]
I won't know how two of these will react to each other. The second one is still being carved up.

Now that the initial listening test of the first enclosure is done, I started sealing it off:
[IMGDEAD]http://img261.imageshack.us/img261/7302/sany0054ek6.th.jpg[/IMGDEAD]

Thanks for the comments & suggestions! I might stick with my existing drivers for the moment & live with them until I get a better idea what to do.
 
Painting on the first one is nearly done! Happy New Year, BTW!
Mynamid_without_Tape.JPG

http://picasaweb.google.com/ascottk/MynamidSpeakerDesign

I had a thought a while ago. I think I'll make subs to go with these so the bass doesn't need to go down very low. The subs will be similar in design & the Mynamids will sit on top of the subs. Any thoughts on woofers?

Another question:
How would I integrate the Vifa D26NC55 with the Yamaha mid & woofer? A clue in the xover components:
  • the tweeter has a 1.5 mfd capacitor
  • the midrange has a 3.3 mfd capacitor
  • no other xover components are on the Yamahas
 
Ouch! Triple posting . . . like anyone is in any rush to reply :rolleyes:

The first speaker enclosure is done! The second one is being sealed & shaped.

I did some further searching & I came up with some drivers that are easier to work with (along with the Vifa D26NC55 - ordered from Madisound):

HiVi F8 Bass-Midrange (8 ohms):
http://www.swanspeaker.com/product/htm/view.asp?id=74
[IMGDEAD]http://www.swanspeaker.com/product/curve/f8-sm.jpg[/IMGDEAD]
[IMGDEAD]http://www.swanspeaker.com/product/curve/f8-zm.jpg[/IMGDEAD]

& Tangband 50-1426SA (6 ohms):
http://www.tb-speaker.com/detail/1208_03/50-1426sa.htm
[IMGDEAD]http://www.tb-speaker.com/detail/1208_03/50-1426SA/50-1426sa_5.jpg[/IMGDEAD]

Here's the latest in speaker workshop:
[IMGDEAD]http://img263.imageshack.us/img263/904/mynamidfreq3ve3.th.jpg[/IMGDEAD]
[IMGDEAD]http://img230.imageshack.us/img230/8996/mynamidimpedance3jn8.th.jpg[/IMGDEAD]
[IMGDEAD]http://img230.imageshack.us/img230/1306/mynamidxover3vc7.th.jpg[/IMGDEAD]

Should I worry about the impedance?
 
As others have pointed out, designing a passive XO for this will be nearly impossible for someone of your experience (mine too), so I would suggest that you go active, using something like a Behringer DCX2496 (cheapish).

I believe that with your PA experience, you will be able to better a passive XO as there will be no components to interfer with the drivers' optimum performance. You will need two extra amps though.

Nice cab design.

Good luck
 
Active xovers are not an option. I have limited space & limited finances. Also I need to keep my surround setup.

Besides, my limited experience with woodworking and painting didn't stop me from making a solid enclosure. I've been running the finished one through its paces with the Yamaha drivers and so far it's superior than the original Yamaha box (the bass port, semi-time aligned, and non-parallel sides make a gigantic difference). I think DIYers would cringe at the enclosure Yamaha put together (1/2" mdf with minimal bracing) That thing resonates and rattles big time around 200 Hz.

And there's plenty of resources online to get the 3-way passive crossover working well. I damned determined to get this right.
 
dublin78 said:
As others have pointed out, designing a passive XO for this will be nearly impossible for someone of your experience (mine too), so I would suggest that you go active, using something like a Behringer DCX2496 (cheapish).

I believe that with your PA experience, you will be able to better a passive XO as there will be no components to interfer with the drivers' optimum performance. You will need two extra amps though.

Nice cab design.

Good luck
Okay, you talked me into it! I found a Peavey PV 35XO for $150. It was a pain to go to an active xover because I am using my existing AV receiver & a Griffin Powerwave to power the speakers. And I'm using my bass port for the extra wires. I may add more terminal plates eventually.

Luckily my receiver accepts multiple inputs (6) except the outputs are configured for a 5.1 setup. So I used my Griffin Powerwave's speaker breakout to power my woofers. It works great except I lost my surround sound. I can regain it with some active monitor speakers since I have six free outputs on my FW interface.

You're right, it would have been impossible for me to design a passive xover since I don't have any local connections to try the designs out first. It is a little tricky to find the right balance with an active xover. Now I know it would have been impossible trying out a passive design! Another plus is finding the weaknesses of the drivers. You can turn off any of the drivers & just listen to one by itself. I do need to upgrade the drivers! I was wrong about the HiVi F8, BTW. The diameter is too big. I think I'll try out the HiVi M8N but I think I'll find a midrange that can have a lower crossover point. Maybe a full range driver around 4" or 4 1/2"? Tangband or Fostex seems to be popular.

Currently I have the xover points around 225 Hz and 1700 Hz for the Yamahas (seems like a happy medium so far). They'll probably distort at higher listening levels but I rarely listen to music above 83 dB which is the recommended listening levels for mixing & editing:
http://www.digido.com/bob-katz/level-practices-part-2-includes-the-k-system.html

I'm not sure I want to go back to passive! These speakers are getting closer to the way I want them to sound.

Will this thread eventually have another page? This is too graphic intensive . . .
 
Congratulations.

You will doubtlessly save money in the long run, as you will not purchase incorrect XO components, also you will be able to use the active crossover on many projects in the future.

If you think about it, putting inductors, resistors and caps in a signal path cannot be ideal. An amplifier per driver makes sense too.

Keep an eye out for a secondhand DCX2946. It does all this and more within the digital domain and acts as a decent DAC too. It can be made into a fairly high-end DAC with a few mods.

Your unit looks well made and simple. Nice price too.
 
Mynamids are done!

[IMGDEAD]http://img81.imageshack.us/img81/3817/mynamidcompletevp1.th.jpg[/IMGDEAD]
Yay! All of my drivers are here & installed:
  • Vifa D26NC55
  • Tangband 50-1426SA
  • HiVi M8N
Currently crossed over at 300 & a little over 2500. I tried crossing over above 500 (since the Tang Band's Fs is 500) but it sounded terrible.

I listened to a lot of different types of music, it helps to be a graduate of music since we have a lot of listening to do, and everything sounds great!

Although I made a bad choice for a 4-position terminal plate:
[IMGDEAD]http://rsk.imageg.net/graphics/product_images/pRS1C-2265719w345.jpg[/IMGDEAD]
Never buy a Radio Shack 4-POS terminal, it leaks like hell & it's too small. Talk about speaker flatulence . . . So I took some cardboard & liquid nails to seal them up. There's still rattling in my right speaker but only on one electronic piece.

I spent the last hour with a grin on my face :D These sound a lot more natural than the Yamahas! On Bobby McFerrin's "I Hear Music" I feel it when he's thumping his chest while he's doing his scat thing. I noticed things in Beethoven's 9th Second Mov't I didn't hear before and it's the closet I've been in a recording. Scott A. Wyatt's "On a Roll" (Music from SEAMUS vol. 14), an electronic piece where balls are rolling around all over the place, is a showcase for panning & sound fields that left me grinning even more! Satriani's stuff sounds better than ever, Audio Slave is less harsh, 90's Depeche Mode sounds good, etc.

If I were to do it again, I would take Hezz's suggestion about adding a shelf to separate the tweet/mid from the woofer & have a bigger midrange so I can properly xover around 200-300 Hz. As it is now, I am extremely happy so far! There's a few tweaks to be made but so far so good. I may try to flush mount the tweeter & mid but that may be a little difficult due to the angle between them (I need a skinny router if there is such a thing). Oh yeah, I would use a table saw so I wouldn't have to use so much patch to cover my mistakes! I would use different paint too.

As for the new drivers, even though they're not broken in yet, I think the Vifa & the Tang Band work very well together since both a textile domes and they nearly disappear. Cymbals sound like cymbals without sounding electronic & syllabants are more natural. The HiVi looks pretty cool & so far the lower string section and timpani in symphonies (I almost feel like I'm at the concert) and other bass material sound terrific!

As an engineer I have to see how well they translate to other systems.