Transmission line bass cabs

Discussion in 'Amps and Cabs [BG]' started by Bass Unique, Nov 3, 2011.


  1. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    Hello - My first post on this site. In a previous life I designed loudspeakers and since I am now gigging, it was only a matter of time before I wanted to build a custom cab.

    I wanted something different so I thought about using a transmission line design. This offers a lot of advantages:

    1) Nice smooth and tight deep bass
    2) A flat impedance curve
    3) good cone control

    So, I set about making one over the last few weeks in my spare time and tested it today for the first time. In this speaker there is one Eminence 3012LF in the main transmission line, which is 1.6m long, tapered and lightly stuffed where required, and also a mid and tweeter. I have been pretty compact and it has ended up similar in size to a reflex box rather than much bigger (as classic lines typically are).

    The bass was awesome - very well controlled, deep and powerful yet smooth and articulate. the cab has also got a small foot print and is currently 22 kgs but it cold be made less than 20 kgs by tweaking a bit. Think "Fearful" in terms of tonality and size but more and even tighter bass allowing a very flexible rig.

    I have setup my company Low Frequency Solutions Ltd (not yet trading) so I can use this name on the products. I will be making more, probably a 10" version right up to an 18" bone shaker. All would use neo drivers to be light weight.

    I would like some feedback as to what the market is like for this type of speaker - what do people actually want for a bass rig and how much would you want to pay? what finishes do people like? This speaker is very tweakable between very deep and smooth (yet tight) and huge output.

    Any comments and suggestions welcome. I have kept a build log and pics if anyone needs information.
     
  2. jpknox

    jpknox

    Oct 7, 2011
    Knoxville TN
    PICTURES? everyone will want to see it - finish depends on the buyer - tolex and duratex seem to be the current fashion - choice of metal grill or speaker cloth - and of course we want to hear samples of what you've got!
     
  3. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    ok - will sort out the pictures - the thing is, everyone wants a different look or wants a different mid balance etc. My thought it is come up with a design that would work for the bass and let others decide what they want in terms of options. For example, I went for a larger mid than most people as I like a lot of low mids. (10 inch instead of usualy 6 inch)
    but there is method in my madness)

    If everyone here could post what they would really like in a cab, as a sort of a wish list, I will post a popular transmission line design for free for everyone to have a look at and see what you think. Someone will build it and hopefully will get a good review! :)

    I will take it to a practice tonight and a gig next week and report back.
     
  4. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Bass Unique,
    Are you familiar with Euphonic Audio? They have been building transmission line cabinets since 1997. I have their VL 108, VL 110, and VL 208. Their current line has several transmission line speakers the Wizzy 12 M Line especially comes to mind. I'd investigate their products.

    Ric
     
  5. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    Yes! I have seen these but these tend to be lower powered speakers or smaller drivers in regular cabs. there are not many designs around like this and I suspect it is because they are not often designed well or a compromise.

    Check the impedance curve - is it flat like a T-line should be or spiky like a reflex box - I would guess the latter.

    Anyway, the whole idea of this is for me to provide designs to the DIY market for this type of speaker at very low cost (around £10 per design), not for me to make them. I am hoping to come up with a range of inexpensive and simple to make cabs for people to use or for a small extra fee, eventually design custom cabs to the customers requirements (POA). They would still make it though (or commision a local wood shop to assemble it / finish it).

    It is exciting to try something new and see if it works and makes you feel proud you made it! :)
     
  6. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    One thing to be aware of, that can (and will) make you look like either a demigod or a braying ass in this forum: Make sure your acoustic science is unimpeachable, and that your cab designs reflect that science.

    We regularly get cab builders, of all budgetary levels, come in here showing off their new designs, only to find themselves face-down in the mud because they were just "box stuffing", or using guitar-cab concepts, or reinventing a wheel that had been discarded as undesirable decades ago. And we are not dumb about these things.

    But then on the flip side we also have a cadre of cab builders who know their #### inside and out, and who have seriously done their homework. We venerate, appreciate, encourage, and financially reward those builders.

    :)
     
    PawleeP likes this.
  7. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    thanks for the advice :)

    I assure you, I design with the correct Kung fu and part of this is to resurrect the T-line as another option for the masses as I don't believe there is a DIY design off the shelf for bass guitar cabs.

    I suppose the closest thing I aspire to is doing something like Bill Fitzmaurice has for horns but with transmission lines.

    It is a cab genre that has had many different approaches and it is notoriously difficult to model and get working well.

    I will be honest - its a hobby not a business at present but just wanted to know if it would generate some interest!

    Keep it comming!
     
  8. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    The earlier Euphonic Audio stuff as I recall it, had listed specs that somewhat matched what I was hearing. More recent EA stuff has steadily gotten inflated specs, that I have to doubt they can all exist in a box that size and weight even before a true transmission line is added too ; }

    I'm not knocking the sound of the EA boxes, fans - just sayin'...

    ...So it would be interesting to see a verified true TL and see about where it's falling in in various areas.
     
  9. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Greenboy,
    I only own the VL series cabinets that EA built
    because they sound great with Double Bass. I've moved to other cabinets because the VL series isn't a particularly good cabinet for doubling, IMHO. The Thunderchild 112 has it all IMHO.
    I didn't move to the CXL series because they were very heavy little boxes. I was very interested in the NM 208 but there wasn't enough interest for it to fly commercially.

    Ric
     
  10. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    I suspect Greenboy is correct - the specs may be inflated on the later Euphonic stuff (cant comment as I have not heard/tested them). Making transmission lines compact usually either limits output or tunes them way too high.

    One good thing about transmission lines for bass guitar is that you dont need a lot of output below 30 Hz (or 40 Hz if you are a 4 stringer) and they have a nice smooth roll off like a sealed box (with more output) so you can actually tune the line to around 45/ 50 Hz and it will still go plenty deep enough.

    I will run a test on my line at 1m in free space (outside) and see what levels it produces compared to a reflex box with the same driver.
     
  11. staindbass

    staindbass

    Jun 9, 2008
    sounds like a great idea! on the negative, doesnt it require a larger cabinet than normal? i think the bass market needs more fidelity and lower range. you can stack up all kinds of cabs but it doesnt go any lower it just gets louder. bassists are competing with synth's nowadays, those low cool bass keyboard sounds that you feel and shake the room. a 5 string bass tuned down is around a 30 hz fundamental, it would be nice to have something flat down to there.
     
  12. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    Prototype CTL 1210 speaker small.jpg

    The picture is of the prototype. It could be about 100mm shorter with a 6 instead of the 10 mid and then it can be made from preferred sizes of sheet wood from B&Q etc. right off to test it in anger....
     
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    There's a reason why I don't do TLine bass cabs, and that's because IME they don't offer any advantages over reflex. If I thought they did I'd do them too. If you really want to do this you will have to document your results very well. To be acknowledged as half as good as commercial designs you'll have to prove that they're twice as good.
     
  14. will33

    will33

    May 22, 2006
    austin,tx
    Well...you got me interested.

    As others have said, don't skimp on the design, make it true blue. Some of the craze nowdays is everything small, light, compact. That's really not a T-line thing outside of really small drivers but there are some of us (like me) who while we appreciate dragging less/smaller stuff around, it isn't worth it if it means settling for less in the sound dept.
     
  15. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    Thanks Bill - very good advice there. However, although a horn tends to offer a large output compared to reflex, I was focussing more on similar output to a really good reflex but better bandwidth, transient response and lower distortion. Although horns can be louder, to get as low does require a lot of size. Having the reverse taper helps a lot! :)
     
  16. Bass Unique

    Bass Unique

    Nov 3, 2011
    Wiltshire
    Just to let you know for a comparison, this is currently smaller in size and lighter than a Genz Benz neoX 212 cab....
     
  17. ACB0015

    ACB0015

    Oct 27, 2010
    Portland, Maine
    Good luck in this, it's always interesting to see people going after more and better sound. I had a couple EA VL110's when they were the greatest in small, they have long been eclipsed. I will just say as a player that reflex cabinets have worked best for me on stage. To me compactness rather than weight is more important, excellent sound quality has become a given in bass cabs if you are looking in the arenas on this forum that above posters have referred to. It is a demanding crowd. I encourage you to do your best!
     
  18. Cabinet design isn't a strength of mine (no kidding!) but I accidentally built one of those transmission compartments a few years ago for my auto sound system.

    It was cochlear in shape, but relied upon the same idea of the diminishing diameter of the 'tube' itself::

    TransmissionLineSpeaker.jpg

    I used a cochlear shape to save space and it was extremely powerful and much more responsive than I though it should or could be. I even amazed myself.

    My design, however, was not vented nor open at the very end.

    The only problem I see in the transmission design is that it usually requires multiple dampening materials of increasing density and property as the tube itself gets smaller and smaller, without choking off the responsiveness of the higher frequencies as the sound gets toward the smallest diameter.

    Unfortunately, that whole sound system went with the car when I sold it. .
     
  19. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    One of the challenges with transmission lines is the upper-bass cancellation notch at the frequency where the line length equals one wavelength. Have you run into this?
     
  20. Robby Hoinsky

    Robby Hoinsky

    Dec 28, 2010
    New Haven, CT
    Art of Noise Audio, fEARful™ builder
    seems interesting. I'll wait to see some specs and measurements and maybe a recording or two.

    How is the response and sensitivity of it affected by the T-line vs. a vented cab?

    Robby
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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