neocon58 Posted February 3, 2007 Report Share Posted February 3, 2007 Hey, I own a Hughes & Kettner Edition Blue 60R. It's a pretty sweet amp, I must say. Enjoy playing it, cleans sound great, distortion takes me a while to get my head around but sounds good. I'm looking for a bit more 'spread', I guess you could say. I know plenty of people that just plug their combos into a 2X12 or 4X12 cab that they buy, but the Edition Blue dosen't have a ext speaker out... I've also heard of a guy who has modded his edition blue and installed a speaker out jack. Now i'm reasonably cluey when it comes to this sort of shiz, well at least i think i am but theres plenty of people on here that would know if A) its possible its worth it C) whether its going to kill my amp in the long run and D) should i just save up for a proper half stack. Are there any sites with tutorials on this? I think its out of warranty, so I may have a crack doing it. Quote Link to comment Share on other sites More sharing options...
jnewman Posted February 3, 2007 Report Share Posted February 3, 2007 Does it have a plug for the interior speaker, or is it just wired directly into the chassis? If it has a plug for the internal speaker, you can just unplug the internal speaker and plug in a cab. You should make sure the cab has the same impedance as the internal speaker (probably 8ohms but you never know). This is particularly important with tube amps. You can often get away with using different-impedance speakers with solid state amps, but I'm not going to tell you to do it with yours because I don't know your amp. So long as you do the mod correctly and use the correct impedance cabs, it should be no different from playing your amp normally and should not affect the life of the amp. I'm not recommending that you do this and there are ways to mess it up that can damage the amp. Additionally, if your amp is a tube-based amp, it has voltages inside that are plenty to kill you! If you have a tube amp and do not know how to work on high voltage circuits, don't work on your amp!. All that said, here is how you would do it if there is no plug for the interior speaker: Mount a 1/4" mono jack somewhere convenient on the chassis (the metal part with the wires inside). You will plug the internal speaker into this jack and, to use an external speaker, unplug the internal speaker and plug in the external speaker. Locate the wires that go to the interior speaker. Locate where said wires enter the amp chassis (the metal part with the electronics inside). Cut the wires, leaving enough for the wires inside the chassis to reach the solder tabs on the jack. Solder the wires to the tip and sleeve of the jack. At this point the guts are ready to go but the internal speaker isn't. There possibly won't be enough wire left to reach the jack, so get some speaker wire, solder it to the tabs on the speaker, solder a 1/4" mono jack on the end, plug it in, and you're done. Again, there are ways to mess this up. I can't promise you won't hurt anything. Do this at your own risk. Quote Link to comment Share on other sites More sharing options...
JohnH Posted February 3, 2007 Report Share Posted February 3, 2007 Mount a 1/4" mono jack somewhere convenient on the chassis (the metal part with the wires inside). I have one concern with this (not sure if it is a problem). A normal metal jack socket has its ground connection in contact with whatever chassis it is mounted on. The output from the amp may be to two ends of a transformer, and not intended to be grounded? If this is a concern - use a plastic jack socket, as on Marshalls. John Quote Link to comment Share on other sites More sharing options...
jnewman Posted February 3, 2007 Report Share Posted February 3, 2007 (edited) Mount a 1/4" mono jack somewhere convenient on the chassis (the metal part with the wires inside). I have one concern with this (not sure if it is a problem). A normal metal jack socket has its ground connection in contact with whatever chassis it is mounted on. The output from the amp may be to two ends of a transformer, and not intended to be grounded? If this is a concern - use a plastic jack socket, as on Marshalls. John From what I know, it shouldn't be a problem. I could be wrong. Might be good to get another opinion besides mine, though . Edited February 3, 2007 by jnewman Quote Link to comment Share on other sites More sharing options...
unklmickey Posted February 3, 2007 Report Share Posted February 3, 2007 hi Jnewman, if there's one thing i've learned, it would be: trust John's instincts, they're usually right. this time he is right, but ironically, for the wrong reason. transformers in tube amps almost always have one end grounded. so one would think that he's worrying about nothing. but this ain't no tube amp. there's a real good chance the output is from 2 complimentary/symmetry chains, neither of which are, or should be, grounded. the best course of action would be to either use a jack ......er i think the English call it a socket, that has a plastic case. or mount a regular socket on a plate attached to the cabinet, so it's not connected to the chassis. i would be cautious about just putting a cabinet in parallel with the speaker in the combo. if they have the same impedance, that means the total will be half of what it is right now. since there isn't a jack on this already, i would guess they designed around the load of that one speaker. you would probably be okay, until you drove it hard, then ................. oops -- big expensive repair bill. wire the combo speaker to a plug. plug it into the newly installed socket, and when you want to use the 4-12 or whatever, disconnect the combo speaker and plug in the cab. check the specs for the combo's speaker. use a cab that has the same or higher impedance. cheers all, unk Quote Link to comment Share on other sites More sharing options...
jnewman Posted February 3, 2007 Report Share Posted February 3, 2007 (edited) Thanks, unklmickey. I have built one tube guitar amp and am getting started on two more soon and have made several solid-state audio amplifiers, but never a solid-state guitar amp . The tube guitar amp I previously built had the output jack grounded to the chassis, and all the audio amps I have made have as well. The only exception that I know of in audio amps is when you're using an audio amp that actually drives the ground signal as a channel instead of holding at 0V. Some higher-end audio amps do this. Edited February 3, 2007 by jnewman Quote Link to comment Share on other sites More sharing options...
MCH Posted February 3, 2007 Report Share Posted February 3, 2007 For my acoustic amp I wanted to able to use my 1x12 cab when I wanted a better sound than the 8" internal speaker of the acoustic amp. So I added a mono switch jack. When I plug my cab speaker into my acoustic amp, the internal speaker disengages and I only get sound from the cap speaker which is what I want. But as mentioned before it's a good idea have the same ohm rating or at least higher. Quote Link to comment Share on other sites More sharing options...
JohnH Posted February 3, 2007 Report Share Posted February 3, 2007 For an SS amp, Ive seen a few combo designs where the speaker is not directly grounded, but connected via another component such as a small resistor . Without knowing, I wouldnt take a risk. And if as Unk suggested, it might be a pair of push/pull output stages, grief could occur. I added a output jack to my 10W Marshall practice amp, and when I tested across the speaker leads I found that the grounded-est wire to th espeaker still had a resistance to ground - So I used an insulated jack. in fact, it was a switched jack so that I can push a plug in to disconnect the internal speaker, and without any momentary shorts. John Quote Link to comment Share on other sites More sharing options...
neocon58 Posted February 4, 2007 Author Report Share Posted February 4, 2007 What do you guys make of this? http://singlecoil.com/docs/external.pdf Quote Link to comment Share on other sites More sharing options...
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