Using a combo amp as an extension cabinet

Discussion in 'Amps and Cabs' started by vintage66, Jan 16, 2008.


  1. vintage66

    vintage66 Member

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    How is this done-I have a Marshall Jcm800 and would like to try using my Traynor Ycv40wr as an extra speaker if it's possible-at least to try and see if buying an extra cab is worth it. How do I hook it up? Do I need a speaker cable or just a guitar cable? Btw, the Marshall's speaker is 16ohm and the Traynor is 8ohm-I want to run both speakers, not just the Traynor.
     
  2. StompBoxBlues

    StompBoxBlues Member

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    Generally, first you have to have speakers in the combo that are not direct wired or else need to do some wiring yourself. What I mean, the Peavey Classic 30 for example has a direct two-wire speaker cable running from the transformer to the speaker. Can't be used then as extension.

    Many other amps I have have (usually way too short to manage to extend to another amp) a 1/4" mono phone plug that plugs into the back of the combo back panel. If too short, one would either have to make an extension cable with speaker wire (NEVER use instrument cable with shield as the negative conductor, has to be dedicated speaker wire) maybe from a female 1/4" connector over to a 1/4" male plug. Plug the speaker jack into the female, and onward into the output of the main amp.

    I would be careful about wiring in another set of leads for this use, as you don't want them shorting out if you are using the combo alone.

    Also, you are aware I guess that you cannot use the combo amp at all, not even plug it in while it is in use as extension from the other amp?

    Also I don't know the specifics of the 800 output...you better get some more input here or at a music store before trying!
     
  3. John Phillips

    John Phillips Member

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    You need a speaker extension cable - that's a specialised cable with a plug on one end and a socket on the other, made with speaker cable. Do not use a guitar cable or one of those 'couplers' made for instrument-level signals.

    You can only do this if the Traynor's speaker can be unplugged from the amp, too (I can't remember if it can with that model). You must disconnect the speaker from the amp and connect the Marshall only to the speaker, not to anything on the amp.

    If there's no speaker plug you could do it by undoing the push-connects on the speaker itself and using a long cable with a pair on the end, but this something you aren't likely to find ready-made.

    If you do find a way to do it, you can run the 8-ohm and 16-ohm speakers together - set the Marshall to 4 ohms - but 2/3 of the power will go to the 8-ohm speaker. This should be OK if it's a 50W Marshall, but might sound a bit off-balance volume-wise.
     
  4. EL-Dougie

    EL-Dougie Member

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    Weber offers speaker extension cables as accessories for their attenuators at this web page:

    https://taweber.powweb.com/weber/acc.htm

    Not sure if they are what your setup will need, but they are definitely speaker cables, and one of them is a Y-splitter (male to 2 female), so maybe that will be a start. The straight connects come in 2, 4 and 8 foot lengths and are male/male or male/female phone plug/jack.

    Assuming your main amp has a speaker cable connected direct to the speaker and plugging in via 1/4" phone plug to the back panel of the amp, you might plug the male end of the y-splitter into that amp, the male from the main combo speaker into one female of the y-splitter, and then run something to the other "extension cab" amp's speaker - if that has a phone plug connect coming off it, then a male to female connect is right. Weber would limit you to 8 feet there, tho. If you are wondering what it sounds like across the room, then maybe a short female to female speaker connect plus a longer standard-issue speaker cable (male to male) from a music store (speaker cable, not instrument cable).

    So you have some connection mapping to consider, as well as the ohms/impedance issues, if any (which I cannot help you on).

    Good luck !

    Doug in CT
     
  5. vintage66

    vintage66 Member

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    The Traynor does have a plug from the amp to the speaker so that's no problem-I guess just the male/female speaker cable ought to be all I need to get going. Thanks for the info.
     
  6. radiohead13

    radiohead13 Member

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    Hello everybody, this is my first post here!

    I 'll set my question here (yes, we have a resurrection) in order not to start a new thread. So, here's the situation... I have a VOX AC15C1 combo and a VOX Lil' Night Train head. I do not own a separate cabinet so I thought if I could use the AC15C1 as a cab for the Night Train. Reading the previous replies I came out that it's possible (taking into consideration that the impedance of the head and speaker are equal).

    My question is how is it possible to connect the head to the speaker? The AC15C1 has two output jacks on the back side, one for connecting an external speaker to the amp (if you connect an external cab into this input the amp's speaker is muted) and a second for expanding the speakers of the amp (you can connect an external cab that runs in parallel with the amp's own speaker). Supposing that the AC15C1 is turned off can I connect the Lil' Night Train head to the speaker expansion input (the one that is for connecting a speaker in parallel with the combo's speaker) without harming the AC15C1?

    I think that it's going to work because of the parallel connection wiring of this input but I'm afraid if there will be any kind of "reverse" current heading from the power amp section of the Lil' Night Train head to the power amp section of the AC15C1 instead of the speaker.

    Thanks in advance for your help!
     
  7. JoaquinReyna

    JoaquinReyna Member

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    Hey I just have the exact same situation going on right now as i type this mesg, i infact was looking for forums on google for an answer lol.
    i too am using a night train with a vox ac15 and it is possible to use it as a cabinet. you plug the the speaker to the vox night train into the 16 ohm, (assuming your vox ac15 speaker is 16 ohm like mine) if not then put it to the 8 ohm. It works perfectly, althought the speaker cable is pretty short, so youll need to place the night train right behind it, im actually serching the internet right now to see if putting a speaker extension cable will work fine with no harm so i can place the night train on top of the combo.
     

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