Cab Construction Investigation

Discussion in 'Cabinets & Speakers' started by pedecamp, Nov 3, 2019.

  1. Matthews Guitars

    Matthews Guitars Well-Known Member

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    There's a huge difference in the way Orange and Marshall make cabinets. Marshall's construction methods using finger/box joints with high quality Baltic Birch plywood qualifies as proper high quality cabinetry. (On their better line of classic cabinets.) Orange does use plywood (on some models) but their joints are simple rabbets with staples through them, with reinforcement glued in behind.
     
  2. dragonvalve

    dragonvalve Active Member

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    You hit upon a magic combination. I think the use of the MDF for front and back within a birch ply shell was the magic. The MDF allowed a dispersed resonance. The birch ply acts like cement to keep the MDF from over vibrating.

    A cab made out of all birch ply might be too rigid. In cases like all birch ply, using thinner sizes will help alleviate some of the stiffness. Instead of 3/4" all around, maybe 1/2" sides and 3/4" front and back or the reverse, 3/4" sides, 1/2" front and back. Something to allow the cab to breathe, flex, balloon slightly.

    Consider that MDF is "oatmeal" ground up Radiata pine from Russia mostly, mixed with glue and then compressed vs birch ply which is criss-cross panels and glue then compressed. I've always considered the Marshall cab to have this "soggy" sound, not meaning a bad tone at all but there's this looseness to the cabinet.

    Your Orange cab with the pine sides and MDF baffles sounds like too much soft wood together.

    Might sound better as a bass cab.

    Also the sound should change if you put in stronger/heavier speakers like EV's or JBL's to do more acoustic work on the cabinet to get the cab to vibrate.
    The Celestions, although classic for a Marshall cab/tone are not that type of speaker.

    [​IMG]
     
    Last edited: Nov 6, 2019
  3. Seanxk

    Seanxk Active Member

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    I think I read in the first post, both cabs are home built.
     
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  4. pedecamp

    pedecamp Well-Known Member

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    I turned it on its side and it sounded fine, not better or worse.
     
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  5. pedecamp

    pedecamp Well-Known Member

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    I originally built the 1936 as an all 3/4" ply cab, the result was it sounded boxy to me. So I replaced the back and baffle with MDF, I decided not to use 3/4" cuz it was too heavy I didnt want the cab to be a back breaker so I went with 1/2" MDF instead, it turned out to be the best sound and overall weight for the cab. So on to the Orange cab, I did the same thing but used 3/4" MDF, the cab is a back breaker as a result and still sounds bad. What if I used 1/2" MDF, I cant imagine it magically fixing this cab so I'm not gonna bother, at this point I'm convinced its the birch ply I used is not good tone wood, its dud ply. :(
     
  6. dragonvalve

    dragonvalve Active Member

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    Yeah If you can sell it rather than tear it apart would be best. Maybe someone could get use out of it.

    Yes, not all wood ply is created the same. When I made some monitor speakers for studio use, I went to the wood store and I knocked on each sheet I planned to use to see if it had a tone. It was arbitrary but at least the sheets spoke rather than sound thuddy.

    Another wood I've used and made it easier to use thinner sizes was phenolic board.

    Not easy to work with from the saw blade end as the adhesive they use for waterproofing the wood (used on boats and as cement molds) will dull a blade after a few minutes and the bowling ball material veneer, unless you cut perfect each side, won't look clean and you can't really paint them. But you can vinyl cover them to hide the scars.

    Birch ply will flake apart over time. Phenolic won't.

    As we find out, building our own cabs is experimental and there are bound to be do-overs until we hit upon a formula.
    [​IMG]

    Phenolic ply
     
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  7. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    I've never heard an Orange cab I've liked. I was sent one by a client to check out, and I wasn't impressed with the joints, or the design, either. I loaded it with speakers, got my cab guy over with a couple of players to test it out.

    That took about 4 minutes total with three different amp heads to realize whatever they sent me sounded awful. Swapped the speakers back to a regular Marshall cab, everything sounded great.

    The one I was sent had four triangular holes in the baffle board, one at each corner, 3/4" ply and it had glue/paint slopped all over the inside. It just wasn't a quality looking or sounding 4x12.
     
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  8. South Park

    South Park Well-Known Member

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    The acoustics of the room is a factor . Playing in the house vs playing in the garage
     
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  9. Matthews Guitars

    Matthews Guitars Well-Known Member

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    For monitors you want those cabinets to be as dead as possible. That generally applies to any speaker that's meant to accurately reproduce the sound of a recording. You want only the speaker to create sound, not the box it's in. But for creating a tone, you may want some cabinet sound.
     
  10. dragonvalve

    dragonvalve Active Member

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    In my case it was supposed to be portable "soffit" monitors from a DIY article posted in Electronic Musician. It involved using a coaxial 12" speaker from Radian.

    The end result; it sounds pretty dead because of the small size of the cabinet and the 3/4"-13-ply birch panels. I also doubled the thickness of the front baffle and countersunk the Radian speaker which was not round but hexagonal frames. Since Radian was up the road from me they were nice enough to lend some bare frames to use as a reference when routing out the recessed areas for the speaker. The extra thickness of an additional 3/4" birch ply baffle acted as a claw for the speaker grill. Don't think the cabinet is going to vibrate at medium studio levels.

    It's a vented design with a port so the sound of the cabinets would not be as dead compared to a sealed type cab.

    What i was looking for ("tone") in tapping the wood to make the cabs, was a similar sound to each sheet purchased for the project to at least make both cabinets closer to being similar sounding specially dealing with studio monitors.

    I also made an 18" bass guitar sub (used with a Hartke HA-7000 bi-amp head) out of the same stock from the wood store's birch ply, of a DIY Parts Express-calculated dimensions and port size design, back when they did such things.

    Thing about birch ply it's not really a "tone" wood per se. It's just closer to cement than cement itself. Meaning a speaker would have less acoustic work to do on the cabinet.

    These days they make clear thick plexiglas speakers. And that might be an ideal
    "dead" sounding cabinet.

    I like this cab project.



    [​IMG]
    Paul W. Klipsch (above) was way ahead of us.

    [​IMG]

    You can custom order from builders in China, plexiglas cabinets. They'll use a machine but you need to send them something mocked up in like CAD or some such software.

    Remember the days when we fiberglassed bass speaker cabinets like surfboards?
     
    Last edited: Nov 6, 2019
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  11. Matthews Guitars

    Matthews Guitars Well-Known Member

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    If you want to know about speakers with really acoustically dead cabinets, my home speakers have midrange/tweeter enclosures made of a material that is a composite of cement and resin. Resonant as a block of well damped granite. The bass cabinets contain a single 280mm woofer and the cabinets are about 220 pounds by themselves. System frequency response is -3db at 21 Hz. Heavily internally braced with two inch MDF inner walls. And then there's Wilson Audio, which makes its cabinets out of sandwiches of materials that are most closely related to kitchen countertop solid surface materials like Corian and competing brands. Some companies like YG Acoustics have made entire enclosures out of inch thick aluminum plates. It can get pretty extreme, when you're willing to pay for it.
     
  12. dragonvalve

    dragonvalve Active Member

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    Now that's a lot closer to my beliefs come to fruition!

    I've always imagined cabs made of slate. Like making pool tables.

    But yeah it is extreme.

    Great going you actually thought enough to do what you did!:cheers:
     
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  13. Matthews Guitars

    Matthews Guitars Well-Known Member

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    I didn't make them. My speakers are Aerial Acoustics 10Ts. They call the upper enclosure material "Novalith".
     
  14. dragonvalve

    dragonvalve Active Member

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    Ok. They make speakers that look like you might find in a mastering suite.

    Serious cabinets.
     
  15. ampeq

    ampeq Well-Known Member

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    I bought a 2-12" Orange cab with "semi-open" back a few months ago. No matter what I played through it, amp or guitar, it sucked. I could not make it sound good at all, so I sent it back. I got one of the new Peavey cabs for almost 1/2 as much with 2 Greenbacks in it and it sounds great.
     
  16. pedecamp

    pedecamp Well-Known Member

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    I picked up a used creamback the other day and tried it in a few cabs, its a great sounding speaker. So I decided the quickest and easiest thing to do is cut up the Orange cab and recycle the hardware and some of the wood to build a 1x12 SV cab for my SV20H, dimensions are about 19x19x9 and a third open back just like the Marshall SV cab. I will do a rough mock up and test it before I do any finished refinements. Wish me luck.

    One thing, I have an opportunity to go 12" deep, I think I should try this before cutting it to 9". :yesway:
     
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  17. Geeze

    Geeze Well-Known Member

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    I'm interested in what you find.

    I've only built one open back cab for a guitar show - it's a crazy ass 1987 combo - 9" deep and it sounds fine. I vaguely remember doing some research and 9"-10" seemed to be the consensus on combo cabs. Marshall's combo cab I have from the 70's is - surprise - 9" deep. Deeper seemed to be 'boxy'. Of course hearing is very subjective and your results may vary.

    One other note - if the plywoood from the 2x12 has sonic issues [thinking voids] you may be rebuilding another problem child.

    Russ
     
  18. pedecamp

    pedecamp Well-Known Member

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    Now youre making me think I should go 9", I was leary about 12" anyway thinking it might throw it off sonically. Im not gonna do any finish detail to it so its just cutting up plywood and screwing it together, I'll know if sonic problems follow then that wood will become firewood LOL. The exterior is cut and screwed, lunch break right now then I'll cut out the front and back hopefully within the hour and I can test it! :yesway:
     
  19. pedecamp

    pedecamp Well-Known Member

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    Its too woofy 12" deep, I took the back panels off which helped but I think I'm gonna cut the depth down to 9 3/4" like the Marshall SV cab. I did use MDF for the baffle, I'm tempted to make one out of ply just to hear the difference, MDF baffles always sounded better in my other builds.
     
  20. Geeze

    Geeze Well-Known Member

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    12" seems to be the depth for closed back depending on volume. I've never messed with mdf baffles or backs always been a 3/4" BB ply guy. It's funny how some folks swear the baffle needs to be thinner to allow flexure - that always struck me as wrong - thinking about the speaker frames being flexed. I can't image they'd like that.

    Russ
     

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