>

Cable question

Discussion in 'Cabinets & Speakers' started by GregM, Jul 6, 2021.

  1. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    So the "vintage" Lorantz cab I just got has a stereo input for 8 ohms, 2 1/4 inch jacks, and a 4 ohm mono input, an xlr male output for some reason.
    Now I want to run the cab in mono from a bugera ps1, and I don't want to make the cable myself ( I suck at soldering) and want something I can rely on a little more.
    So I've been looking for chords and most I seem to find are microphone cords which I assume are like instrument cables. Ie bad.
    So I've looked at a few connections to connections to get a xlr female to 1/4 inch male, but the only seem to say balanced or unbalanced, and I'm not sure if one is instrument and one is stereo?
    Any help appreciated sorry and Ty
     
  2. fitz288

    fitz288 Well-Known Yinzer Silver Supporting Member

    Joined:
    Apr 7, 2020
    Messages:
    2,826
    Likes Received:
    6,593
    Location:
    rahndahbaht dah 'Burgh
    missing information: does your amp have 4ohm out?
     
  3. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    Not yet, when I get the sc20h it will, at the moment I have only run in stereo mode state thru my ac15c1 using half the speakers just to test them.
    They sounded really good surprisingly using only half the cabinet.
    But I don't want to get the sc20h and then not be able to play it as intended so prepping everything now
     
  4. fitz288

    fitz288 Well-Known Yinzer Silver Supporting Member

    Joined:
    Apr 7, 2020
    Messages:
    2,826
    Likes Received:
    6,593
    Location:
    rahndahbaht dah 'Burgh
    Are you saying that the 4ohm mono jack on the speaker is only xlr only?
    Easiest solution may be a cab rewiring.
     
    Jethro Rocker and PelliX like this.
  5. PelliX

    PelliX Well-Known Member

    Joined:
    Jun 16, 2020
    Messages:
    835
    Likes Received:
    1,348
    The Bugera PS1 XLR connection is not a speaker out, but you could modify that... requires some soldering though, so you just want jack to jack - and indeed a speaker cable, not an instrument cable (though at lesser wattages you'll get away with it).

    Not really important, the PS1 has a 4, 8 and a 16Ohm input which is all the amp sees, regardless of attenuation level.

    Sounds like it. Any chance of an exact model number or some pics? :)
     
    Jethro Rocker and fitz288 like this.
  6. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

    Joined:
    Mar 11, 2011
    Messages:
    9,950
    Likes Received:
    14,705
    Location:
    Saskatoon, Canada
    The PS1 has inputs for 4,8 or 16 but what output? Ie- can OP run 8 ohm out to PS1 and then into a 4 ohm speaker? Seems wrong to me?
    Does the cab have an XLR ONLY for 4 ohm input? I would not dick around with adapters, they will most likely be shielded which is a no no for speakers.
     
    fitz288 likes this.
  7. PelliX

    PelliX Well-Known Member

    Joined:
    Jun 16, 2020
    Messages:
    835
    Likes Received:
    1,348
    Correct. The PS1 doesn't really care about impedance of the attached load...
     
    Jethro Rocker likes this.
  8. Dogs of Doom

    Dogs of Doom >>> Moderator <<< Staff Member

    Joined:
    Aug 2, 2012
    Messages:
    25,532
    Likes Received:
    32,461
    Location:
    Los Angeles
    1st off, what is the rating of each speaker individually?

    Are they both 4Ω?

    I'd confirm how the XLR is hooked up. Could you post an image (or images) of the cab?
     
    PelliX likes this.
  9. RLW59

    RLW59 Well-Known Member

    Joined:
    Nov 30, 2017
    Messages:
    1,082
    Likes Received:
    1,239
    It's a 4x10 referenced in an earlier thread:
    https://www.marshallforum.com/threads/interesting-lil-pickup-maybe-lorantz.121213/
    -------------------------
    Pics of the cab's inputs would help a lot. And pics of the wiring running from the inputs to the speakers.

    Have you checked the inputs with a multimeter (or at least verified the wiring) to be sure things actually work the way they're labeled?
     
    Last edited: Jul 6, 2021
    PelliX and Dogs of Doom like this.
  10. PelliX

    PelliX Well-Known Member

    Joined:
    Jun 16, 2020
    Messages:
    835
    Likes Received:
    1,348
    Just a sidenote; although I agree that an adapter is sub-optimal solution and should only really be considered in cases like this when a non-transparent load is placed in between the amp and said adapter, this shouldn't really cause any problem. Any length of cable that's shielded instead of an adapter would be a bad idea, but just an adapter that happens to connect speaker negative to its sleeve is not going to be an issue. Most jack plugs (including the ones super duper unobtanium speaker cables) have the sleeve bridged to the negative. Provided the shield (if present) of the cable is not terminated at both ends, you're effectively just creating an antenna, but in this low resistance circuit that won't be a problem.

    So indeed, its most likely 4Ohms in total (4x 16Ohms in parallel). I'm using 'most likely' as nobody knows what may have been done on the inside. If OP has a regular multimeter - let's see what that says. The XLR is (and I'm just guessing here, really) a stereo connector which, provided the positives are bridged, becomes 4 Ohms mono (vs 2x 8Ohm, i.e. L and R, respectively). @GregM You have a meter, right? :)
     
    Jethro Rocker likes this.
  11. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    Sorry, been asleep. The speakers are 16 ohm.
    Yes it's a 4x10. I do have a meter but the guys at the shop tested it for me as nothing is labelled, except the speakers ( I pulled of one of the side handles and snuck my phone in there for a better look)
    IMG_20210707_061644.jpg
    The back of the cab as seen here
    The inside of the backplate
    IMG_20210707_062436.jpg
    The red sleeves are the 14 inch jacks, the silver cylinder the xlr out and the screwed in terminals the switch
    A better photo of the xlr out IMG_20210707_062358.jpg
    Sorry, if better is needed please feel free to ask
    Ty
     
  12. PelliX

    PelliX Well-Known Member

    Joined:
    Jun 16, 2020
    Messages:
    835
    Likes Received:
    1,348
    Right, thanks for the pics. So, er, the solderwork looks like a right bodge. Neither the XLR nor the Jack marked 'S7' or '57' look original (though that jack might be). The red jacks... could be replacements in original holes, not sure. Long story short, measure the impedance on the inputs, but I would suggest getting this fixed up anyway or doing it yourself, but you mentioned you weren't too handy with a soldering iron.

    Getting this straightened out is no more than a half an hour's work, and I'd gladly do it for you, were it not for your location on the other side of the earth. Seriously, it's in need of de-bodging, though. If you decide to go with it in this state, then measure for an input of your desired resistance (+/-) and see whether all 4 speakers are connected...
     
    Jethro Rocker and nickfox like this.
  13. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    Probably the best idea though one I wanted to avoid. I guess if I took it to someone smarter they could make the mono 16 ohms with a 1/4 inch jack and save me a few headaches.
    Cheers and Ty for the responses!
     
    PelliX likes this.
  14. ricksdisconnected

    ricksdisconnected Well-Known Member

    Joined:
    Aug 11, 2019
    Messages:
    9,468
    Likes Received:
    15,253
  15. fitz288

    fitz288 Well-Known Yinzer Silver Supporting Member

    Joined:
    Apr 7, 2020
    Messages:
    2,826
    Likes Received:
    6,593
    Location:
    rahndahbaht dah 'Burgh
    You might be able to just buy a jack plate and a wiring harness.
    Plug & play, just need a screwdriver, and a waste basket for that mess of lamp cords.
     
    Jethro Rocker likes this.
  16. RLW59

    RLW59 Well-Known Member

    Joined:
    Nov 30, 2017
    Messages:
    1,082
    Likes Received:
    1,239
    Yeah, I'd definitely just replace that mess.

    Building/repairing amps, you absolutely need to have good soldering skills, a good (relatively expensive) meter, and a good (relatively expensive) soldering station helps a lot.

    But speaker wiring is basic and crude, so it's a really great place to start soldering. Soldering to jack & speaker terminals is actually easier than soldering the ground in a 1/4" plug.

    A $10 pencil-type soldering iron and a $10 multimeter to check your work are perfectly adequate for cab wiring. (Most cheap soldering irons come with a spool of solder.)

    If the wires are soldered to the speakers, or if you want to reuse the jacks, add a $10 spring loaded solder sucker, or a $5 roll of solder wick to remove the old solder.

    The existing wires are bigger than they need to be, but they're fine to reuse. And if you just want it wired for 16 ohm mono you'll just have to make a few connections. Nowhere near as intimidating and confusing as the mess that's there now.
     
    PelliX and ricksdisconnected like this.
  17. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    Yeah I have rethought and decided to do it myself.
    I was thinking of leaving the two stereo plugs as is, and I know I can change it to 4ohm mono easy peasy, 2 wires to unsolder, 2 pop rivets to drill out and resolder wires to either side of the jack.
    Going about making it series from the 2 stereo jacks confuses me, on a speaker easy, bridge a pos and negative and run a pos neg to to other side of the 2 different speakers, this bit stumps me a bit on switches though
     
    PelliX and ricksdisconnected like this.
  18. RLW59

    RLW59 Well-Known Member

    Joined:
    Nov 30, 2017
    Messages:
    1,082
    Likes Received:
    1,239
    Do you actually plan to ever run it in stereo?

    There are wiring diagrams everywhere that show the ways you can wire it for mono 16 ohms. But looking for a wiring diagram using a switching jack with 2 pairs in parallel for stereo, connected together in series for mono made my brain hurt so much I gave up.

    If you don't need the stereo option it's simpler and easier to disconnect all the wires from the jacks, then just start from scratch.

    We haven't seen the connections on the speakers. Depending on how weird they are, it might be simpler to disconnect them too, then start from a completely blank slate.
     
  19. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    IMG_20210707_113307.jpg
    Sorry, best photo I have, at work right now.
    I was thinking of keeping the stereo jacks hooked up so if I screw anything up they are my get out of jail free card.
    Then I could always buy another attenuator to run in stereo ( which I don't really want to do but it's a last resort option)
     
  20. GregM

    GregM Well-Known Member

    Joined:
    Nov 18, 2020
    Messages:
    1,096
    Likes Received:
    2,112
    Location:
    Australia
    I think I see a few things the make me puzzle.
    The speaker cables seem to go to the stereo input jacks, then are attached to the switch after?
    Shouldn't that be the other way around?
     

Share This Page