Speaker building all by yourself

Discussion in 'DIY' started by Priidik, Jul 28, 2020.

Tags:
  1. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    How did you simulate the transmission line? Do you have any diagrams of the inside?
     
  2. Martigane

    Martigane Acquaintance

    Joined:
    Mar 5, 2019
    Likes Received:
    97
    Trophy Points:
    18
    Location:
    Belgium
    For the transmission line characteristics, I ended up finding the best compromise for this driver (SB34NRXL75-8) as below:
    • 94Liters
    • TL length of 1.82m
    • Driver offset of 0.26 (distance from closed end)
    • Tapper ratio of 6.5
    • 150cm2 area for the open end (dictated by air velocity sim below)
    This SB34NRXL75-8 woofer is very good; maybe a touch too low Qts for a TL.
    Challenging but doable, so I wanted to optimize the TL as much as possible.
    See woofer measurements:
    https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb34nrxl75-8

    Transmission Line has first been simulated in HornResp:
    [​IMG]
    One of the criteria for this design was to avoid compression occurring in bass reflex, and reach the critical port air velocity leading to chuffing of 17m/s only above the woofer's rated specs, so that it stays all nice an clean even at high level.

    Then as soon as cabinets were glued, I performed a measurement without any stuffing to verify that the line tuning (and its harmonics) properly matches simulation. Happy to find a good match! :
    [​IMG]
    As can be seen below, the actual construction has several folds that were not simulated in HornResp ; which explain the additional Low pass effect we see on port response. (Good)

    Then I tried various stuffing configurations to compromise extension Vs harmonics attenuation:
    [​IMG]
    It was really hard to get rid of the 7th harmonic without degrading the bass extension.
    I ended up with a fine lining after the second half of the TL length (not shown here):
    [​IMG]
     
    • Like Like x 4
    • Epic Epic x 1
    • List
    Last edited: Nov 27, 2021
  3. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    I wanted to see if I could get some ideas for ways to finish speakers to take some abuse. Motivation is to not freakout at kids or dinner party guests constantly worried that they are going to damage the exterior.

    Some ideas:

    -Delay finishing

    Basically I would just leave the speakers as unfinished until the kids are at a non-destructive age and then I would complete the speakers. Whatever marking or dents might be on there would be sanded off and painted over. Unfinished plywood actually doesn't look so bad so I think I can live with this.

    -Removable exterior

    The surface would have some kind of vinyl or large sheet with an adhesive side that is strong enough to stick but weak enough to remove. I haven't seen this implemented, it's just a brainstorm I had so I don't know if this is feasible

    -Look at the pros

    Touring musicians use tolex on guitar cabinets and PA speakers with reinforced corners and it's meant to be durable. I'm most drawn to this as it's permanent, but the black cabinets I've seen are pretty ugly.
     
  4. ogodei

    ogodei MOT: Austin AudioWorks

    Pyrate
    Joined:
    Feb 9, 2016
    Likes Received:
    2,765
    Trophy Points:
    93
    Location:
    Chicago
    I guess this comes down to how you want to experience the speakers the majority of time in between these risky events and how you want others to perceive your workmanship.

    Unstained Baltic Birch or Appleply can look pretty good. If you leave them completely unfinished you can steam out dents or replace pieces if anything happens. Problem is unfinished, light-colored wood attracts dust, dirt, hand prints and shoe-smudges. They'll start looking dingy pretty soon. And they'll tan slightly over time in light so new pieces may not match exactly.

    I'd suggest brushing or spraying on lacquer or shellac which would protect from such things (as well as water spills) and can fairly easily be repaired if there are problems later on (look up amalgamating lacquer on the net) . The lacquer protects better but can be a bit tough to brush on. This is how Troels Gravesen finishes his builds BTW.

    Or: Have tough canvas coverings custom made to fit over your speakers when not in use?

    I'm not a fan of the corner bump guards. They generally only work when you're moving the object, not when other things are moving around it.
     
  5. Armaegis

    Armaegis Friend

    Pyrate BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    7,467
    Trophy Points:
    113
    Location:
    Winnipeg
    Spray on truck liner?
     
  6. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    @ogodei - A minimal finish for water protection would certainly be better. I can also see why woodworkers like a dark brown finish as it masks dark discolorations

    Have you seen vids of watermelons covered with line-x?



    drops at 1m30s
     
    Last edited: Feb 15, 2022
  7. ogodei

    ogodei MOT: Austin AudioWorks

    Pyrate
    Joined:
    Feb 9, 2016
    Likes Received:
    2,765
    Trophy Points:
    93
    Location:
    Chicago
    Yes, brown stain on wood grain allows for covering over many sins, much more than a solid color. Lacquer would go over the stain.
     
  8. Armaegis

    Armaegis Friend

    Pyrate BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    7,467
    Trophy Points:
    113
    Location:
    Winnipeg
    New idea: metal grills over the drivers, change the connections to speakon for safety (they're better than posts/bananas anyways), and now just wrap the speakers in several layers of paper and let the kids go nuts with the crayons. They get to share in your space without feeling excluded or being put on edge, and you get to display their art like any proud papa should.
     
  9. yotacowboy

    yotacowboy McRibs Kind of Guy

    Pyrate Contributor
    Joined:
    Feb 23, 2016
    Likes Received:
    10,696
    Trophy Points:
    113
    Location:
    NOVA
    Home Page:
    https://www.homedepot.com/p/Rust-Ol...board-Flat-Black-Spray-Paint-301438/307244901
     
  10. Armaegis

    Armaegis Friend

    Pyrate BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    7,467
    Trophy Points:
    113
    Location:
    Winnipeg
  11. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    I check Paul Carmody's page every so often and he hasn't had anything new in awhile. But for 2022 he has a 3-way 1+5+12 speaker build.

    https://sites.google.com/site/undefinition/floorstanding-speakers/pit-vipers

    I keep making notes for what I want in a 3-way and I feel like a 4-5" mid is what I'm looking for with a +12" woofer. Finding these new plans is very welcome

    The chamber for the mid-woofer he uses a PVC end cap. Niiiiiiice

    Pit Viper Mid Enclosure.jpg
     
    Last edited: Oct 9, 2022
  12. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    So one of the Japanese speaker builders I follow posted some different finishes that I really like

    u-oil_paint.jpg

    They call it paint but it seems more like a stain. I found their website and they got a lot of nice examples. It think it is mainly linseed oil from what I can figure out from translation. Searching extensively it looks like it is only sold in Japan. So I wanted to ask if anyone here would know something similar but available in Europe?
     
  13. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    This reminds me a bit of some of the coverings they feature in the photo gallery for the kanspea kit

    [​IMG]
    [​IMG]
     
    • Like Like x 2
    • heart heart x 1
    • List
  14. Martigane

    Martigane Acquaintance

    Joined:
    Mar 5, 2019
    Likes Received:
    97
    Trophy Points:
    18
    Location:
    Belgium
    So, I've spent some time optimizing the setup pictured below, comparing two 3 way speakers in my acoustically treated lab:
    • My DIY speaker "Saisho", presented in #40 (RCA from BF2, Class A mosfet amp; usb PC)
    • Pro Studio Monitor KLH 310 (XLR from BF2, usb PC)
    Both have a very close frequency response at listening position, but subjectively, the difference was shocking on multiple aspects. (especially soundstage, dynamic headroom, macro dynamics, bass extension / articulation (of course, 8" Vs 12"), realism..)
    At 4k euros, the KLH 310 were noticeably inferior, so much so that I was a bit embarassed for 2 colleagues, one being the KLH 310 owner and the other one drooling on this "dream speaker" for a while now.

    Have any of you tried good Studio monitor?
    Any reference that would outperform the KLH310? (asking for a friend, I'm too happy with mine :D )

    Picture of the setup:
    https://imgur.com/9uwiPal
     
    Last edited: Mar 29, 2023
  15. Armaegis

    Armaegis Friend

    Pyrate BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    7,467
    Trophy Points:
    113
    Location:
    Winnipeg
    Well let's be realistic here... as you mentioned it's a 12" vs 8" and what looks to be nearly five times the cabinet volume. You're not going to find the Saisho sitting on top of a mixing console anytime soon.
     
  16. Martigane

    Martigane Acquaintance

    Joined:
    Mar 5, 2019
    Likes Received:
    97
    Trophy Points:
    18
    Location:
    Belgium
    Yes, so that explains the delta in low frequencies, but what's surprising is that this was not even the most apparent difference. Soundstage and dynamics was.

    We wondered if baffle width ; or putting the KLH too high (allthought they are angled down to be on axis) were responsible for that.

    I will do one last listening session on friday and may try to swap the KLH left/right in order to have the mid/tweeter on the inside.
    I'm open to any idea to give those KLH a fair chance.
    I could also try reducing the listening distance, as they are near field after all.
     
  17. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

    Pyrate
    Joined:
    Sep 28, 2015
    Likes Received:
    4,276
    Trophy Points:
    113
    Dude, you just went seal clubbing with that speaker of yours. For an apples to apples comparison multiply your BOM cost (+shop hours/design) by at least five and you'll get something close retail price-wise. With that said, superb speaker!

    I used to run a couple of KH310's and they're decent. For the price you get a small-ish speaker that will go down to 35Hz, have controlled directivity, good linearity and three Class-AB chipamps to run it all.
     
  18. Martigane

    Martigane Acquaintance

    Joined:
    Mar 5, 2019
    Likes Received:
    97
    Trophy Points:
    18
    Location:
    Belgium
    Fair enough. I still wonder what exactly in the design accounts for the massive soundstage difference.
    I might soon have the opportunity to compare them to 2 other models with very different approach, quite a departure from what DIY can do:
    • PSI A25-M (11k€)
    • Kii Three (14k€)
     
  19. mitochondrium

    mitochondrium Friend

    Pyrate
    Joined:
    Sep 1, 2017
    Likes Received:
    1,115
    Trophy Points:
    93
    Location:
    A Cell
    If you put those on top of your speakers they will sound just as bad as the 310 when you put them there
     
  20. Armaegis

    Armaegis Friend

    Pyrate BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    7,467
    Trophy Points:
    113
    Location:
    Winnipeg
    The KH310 is also somewhere around 81dB sensitivity (rough estimate) versus the Saisho that's 90.5db. That too leads to a huge difference in perceived dynamics because, well, it takes nearly an order of magnitude more power to drive the KH310.
     

Share This Page