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2x10 DIY cabinet, help needed!

Discussion in 'Amps and Cabs [BG]' started by Mixi, Sep 23, 2008.


  1. Mixi

    Mixi

    Apr 9, 2007
    Hi!

    sorry about starting a new thread. I've read a lot about making DIY cabinets but I still got some questons left.

    I'm trying to build as HI-FI sound cabinet as possible to get my bass' real sound without colouring it. Right now I have just 4 string basses but i'm thinking to buy a 5 string one.

    My plan was to copy some specs from EBS NEO-210 cabinet.
    I've already started to build the cabinet from 18mm plywood and the net volume is going to be about 119.56 litres.

    I've been thinking to use 2x Eminence legend b102 speakers with eminence PX2:3K5 crossover (cabinet ready with L-pad) and a good tweeter.

    I was thinking to add 10g mass to the cone to get extented bass and tune the cabinet down to 25hz(or 30hz??) to avoid group delay (and get low).

    And here are the questions:

    - What is a good tweeter? (I've been thinking about eminence apt-80)
    - Is it a good idea to add mass to the cone? (pros/cons)
    - Where can I find how much the speakers take from the cabinets volume? (speakers displacement?)
    - any ideas how to tune the cab better or any ideas about better drivers?
    - how important is it to avoid group delay? (With these specs would be about 13.5ms at 30hz)
    - is it ok to have 8Ohm cross over in 4Ohm cab with 8Ohm tweeter? and is Eminence's crossover good?

    Thank you!

    Mikko
     
  2. spode master

    spode master

    Jan 21, 2007
    The APT wants to cross over too High

    Like 5kHz

    I would like into the Ciare I think its 1.36. You can cross as low as 2 kHz. I would try to mount it without the baffle ring. Get it as close to the center of the woofer as possible.

    Adding mass to the cone in your case probably won't be very helpful. You will probably looses sensitivity, and your driver probably doesn't have enough Xmax for good LF.

    Neither will tuning that low. Why exactly are you concerened about group delay. The only thing I've seen get good group delay for low bass are Bass Horns or Tapped horns.

    I personaly have never been able to say wow I can really hear that group delay vs another speaker.

    I don't know if Win ISD has any driver displacement features but check there.

    Otherewise Eminace's speaker design software (Harris Tech Bass Box Pro) has that feature.

    If you don't want to buy something like that you will need to find the volume of a Frustrum Cone, and the volume of a cylinder for the magnet.

    How do you know your group delay specs. Thats almost like 13' of Delay. I've go a sub tuned to 21Hz and it has a 24ms group delay. It sounds fantastic.

    No your xover will not work correctly with 4 ohms if it is intended for 8 ohms.

    Generic Xovers seldom work optimally.

    It probably works OK for a specific combo of drivers.

    Good luck.
     
  3. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    If you want an accurate sounding cab consider a woofer+mid(+tweeter) design. That's too low a tuning for those drivers. Group delay doesn't matter unless you really screw the design up! I wouldn't use a stock crossover as it assumes a flat impedance plot which is never the case.

    In a cab that size I'd use a 3015LF and a nice 6.5 mid (Beyma, 18sound, Ciare). I think the APT80 could work very well if you want a tweeter as well but not without a mid speaker.

    Alex
     
  4. MellowTone

    MellowTone

    May 26, 2008
    Australia
    My usual equation for that is, upon finding my final calculated internal volume, just add around ten percent (for drivers, bracing, ports, handles, etc.)

    Just a thought on tuning it that low, as well as what others have already said, tuning that low may result in a muddy sound. Even though the E on a four string goes to ~40Hz or so, very few cabinets go that low. Check the specs on some cabinets that are known for being having large quantities of bass, most will be tuned in the mid seventies. (On a related note, I have tried playing my bass through my sub before, IMO it sounded crap)
     
  5. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Tuning that low is unlikely to give a muddy sound but it does mean that the port assistance will be ineffective because the woofers' output will be significantly down before the port kicks in.

    If weight is not an issue (which 18mm ply and non-neo drivers certainly suggest) and you want a near-flat cab with deep response then unless you are ready for a very extensive design process and some significant costs then you might be better served by just buying an Acme Low-B2!

    Alex
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Tuning a cab in the mid seventies will unload the driver below that, the result being a blown driver. :crying:
    While commercial cabs tend to have f3s in the 70s and higher that's the result of using a small cab, not a high tuning. Most cabs are tuned to about 50 Hz, for maximum sensitivity without endangering the driver.
     
  7. Mixi

    Mixi

    Apr 9, 2007
    Well yeah I don't really need it to go so low. I was just wondering cause WinISD showed that if I added 10g mass to the cone and tune the cabinet 30hz response was -4db@30hz.
    I just really want it to be really tight and still have a good bass response but it don't have to go so low. I've practised with my Genelec studio monitors which go only down to 60hz -3db and it sounds great with my fender.
    Why I was thinking b102s was cause they have "a whizzer cone" and should go up to 5khz. And Eminences website told that apt-80's Usable Frequency Range is 3.5Hz - 20kHz. I really don't want any harsh sounding tweeters.

    I'm really open to all new ideas! 3-way system doesn't sound bad either but I just got no idea for example how to build my own crossover.
    I'm in Australia for this year but I'm moving back to Finland after that so it would be good if the parts were available in Europe.
     
  8. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Adding mass to the cone will indeed increase bass extension by lowering Fs and slightly raising Qts but it'll also reduce sensitivity and midrange response. Such is life with speakers - whatever you gain on one hand you almost always lose on the other!

    Alex
     
  9. jsa0100

    jsa0100

    Apr 6, 2005
    Norway
    You will also decrease the power rating of the speakers.
    One hi-fi loudspeaker maker (Seas). Had a 80watts 12" speaker.
    They were asked to modify the speaker for use in a compact 20hz sub woofer, for a Hi-fi speaker kit.
    And so they made a thin round fiberboard that you cold glue on the element. (included in the kit).
    However the new Power handling on the speaker was,
    25 watts !

    The increase in Q can be compensated by gluing an extra magnet (similar) make sure the magnet is repelling if they attract each other turn them around and glue.

    However it's not easy to get a 2x 10" to play deep and loud at the same time and also not being to large. I have tried both with a single 12" or 2x 10".

    But in most case i must use 1 or 2, 15" or 4x10".
     
  10. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    You won't change the (thermal) power handling rating of the speaker but you will increase the likelyhood of the speaker exceeding Xmax by asking it to deliver more bottom.

    Alex
     
  11. Mixi

    Mixi

    Apr 9, 2007
    OK thanks guys now I'm sure that I don't really want to add any mass to the speakers.
    That 3 way system sounds actually good. So how would kappalite 3015LF with a mid driver (maybe eminence alpha 6?) and tweeter ( beyma cp-22 or cp-21? or apt-80) sound?

    And then should I like make a own box inside the box (hope you get what I mean) for the 15" speaker? Or is it just alright to put them into same box?

    And what about the crossovers? Would eminence PXB3:5k0 3- way crossover work (500Hz/5kHz 12db/octave) or how could I make my own?
    And is eminence alpha-6 a good mid driver? (might be easier me to buy)

    Thanks
     
  12. spode master

    spode master

    Jan 21, 2007
    If you want to keep your driver combination and polar response good, I recomend Crossing lower 5kHz is not a great place to Crossover. I like the looks of the APT buts is useful range makes gives it poor combining characteristics.

    The Ciare looks like a good tweeter. Down to 2kHz.

    The Beyma bullet can only really be used down to 3kHz.

    Don't use the slot tweeter. That can't be used lower than 7.5kHz its not much use for Bass.

    If your feeling spunky you could use something like a B&C DE 250 on something like an 18 sound aluminum horn.

    You can Crossover as low as 1200Hz. The B&C is probably the most linear 1" compresion driver up to 16kHz that I know of besides maybe something like a TAD 2000 Series.
     
  13. MellowTone

    MellowTone

    May 26, 2008
    Australia
    Ahh yes, got stuff confused. Fair point.
     
  14. Mixi

    Mixi

    Apr 9, 2007
    Well eminence sells also 3-way crossover which crossover frequency is 500/3.5khz is it still too high? How could I make my own crossover? What does it mean that "a stock crossover assumes a flat impedance plot" and is it a big problem?

    I'll probably use b&c's 1" driver. Is DE 200 a lot more worse than DE 250. And would RCF's H101 horn be good? It would bee small enough with good coverage angle and it's cut off frequency is 1000hz.

    There is not probably enough space for big port so any disadvanges puting it into back panel? or make two of them, one in front and another back?
     
  15. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
  16. Mixi

    Mixi

    Apr 9, 2007

    Thanks!
    "Three-way (and above) will become a nightmare if you must use passive crossovers all the way through"

    Ohh Seems to be too hard for me... if the stock Eminence 3-way crossover really wouldn't work well maybe I could use a active crossover?

    Any ideas?

    Mikko
     
  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Use an existing design.
     
  18. Mixi

    Mixi

    Apr 9, 2007
    Ok thanks guys but I actually ment building my own crossover. I'd really just love to build my own one (and i've already ordered some stuff so I'm really gona build something)
    Full range element would solve this problem.

    Could someone really explane that what does it mean that "a stock crossover assumes a flat impedance plot" and is it a big problem?
     
  19. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    When you combine drivers and a crossover, the response curve of the overall system depends on the characteristics of both the crossover design and the drivers. When designing a general purpose crossover without knowing the nature of the drivers that will be used, the designer can only make an educated guess.

    The difference between a stock and custom driver is like the difference between buying your size of clothes out of a catalog, versus getting them tailored.

    For a bass speaker, I doubt the difference is going to be drastic. Mids and highs can be equalized. In my view, the biggest gamble will be whether the low end response (below 250 Hz) will meet your expectations for how you want it to sound.
     

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