lenaghans1
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Post by lenaghans1 on May 15, 2006 19:40:36 GMT -5
i just got a carlton head. i dont have a cab just combo amps.i have an old marshall twin speaker combo.can i plug the head into the combo and use it as a cab.inside the back of the combo somebody has attached a input socket to the wires that go to the speakers.i dont know if they were using it for the same thing
thanks peter
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Post by JohnH on May 16, 2006 0:36:17 GMT -5
Lenaghans1 - Welcome to GN2 -
It should be Ok in principle, but make sure that you really have a socket that connects you to the speakers in the combo, rather than to the output of the amp, and that the combo's amp output is disconnected and it is switched off. Typical Marshall combos have an output socket from the amp, and a short cord with a plug to the speakers. If you have that socket, dont plug your other amp into it! Dont switch on the combo without speakers connected, particularly if it has a tube output stage. Check the impedance of the speakers and how they are wired and make sure the total impedance of the speaker pair matches the head. If that all checks out, it should be OK. if the head has a higher wattage than the combo, just be a bit careful with the volume!
John
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Post by sumgai on May 16, 2006 12:22:40 GMT -5
Peter, Hi, and to the forums! What John said, with one or two caveats. First, you didn't mention what model of Marshall, so John made a blanket statement that is the safest one to make. For that reason, I agree with him that you must unplug the combo's speakers from their amp before attaching them to your new head. Where John and I differ is that he said "especially with a tube amp", that's not quite right. Tube amps can run at idle forever without a load (the speakers). If you feed in a signal and crank it tiny bit, everything is still OK, but get up much off of zero (or 1 on most knobs), then you're taking a chance of burning up the output transformer. There's another slight error on John's part, and that is, you could, in theory, plug the amp head into the tube combo's Ext Spkr jack (while the combo is OFF!), and let the internal wiring take the signal down to the speakers. However, this will also include the combo's output speaker in the circuit (the secondary windings), and that adds a pretty hefty load to the signal, robbing it of both tone and power. Good enough reason right there to disconnect the speakers, eh? On the other hand, one must never power up a solid-state amp without a load. Doing so is guaranteed to pop the output transistors in a hot hurry. I've seen this very thing done countless times, usually in smaller combo amplifiers where a youngster got a hold of his friend's amp head, and plugged it into his Crate 15 watt combo. Poof! He "forgot" to leave the Crate off. You and I know what he was doing, but attaching blame is way too late, he's in for a healty bill to replace the output IC (about $80, parts and labor). It is unusual to see a higher powered, more expensive combo amp used as merely a speaker cabinet. Was the "input jack" you mentioned attached directly to the speaker wires? Was it done in a professional manner (soldered and taped to prevent shorts)? If not, I'd step back and give this a moment's cogitation. If you are unfamiliar with good soldering and assembly techniques, then I suggest that you read up on other threads here, and that you visit our forerunner site, GuitarNuts. Other websites abound on the 'net that will also give you good advice on soldering techniques, insulation procedures, avoiding common mistakes in placing parts next to each other, etc., etc., yadda, yadda, yadda, blah blah, woof woof - you get it by now. ;D What model of Carleton head did you get, BTW? sumgai
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lenaghans1
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Post by lenaghans1 on May 16, 2006 21:33:11 GMT -5
thanks for the replys.sumgia my amp is an old twin valve state marshall master lead combo.the soldering to the input socket added on, looks alright.its not a professional job.its just hanging there,the wires are not taped up.the head i bought is a carlton high gain series.it is handmade amp by a scottish firm called sound ideas.they are no longer around.it is a secondhand amp i dont really know if it works properly.it all lights up outside.the valves all light as well
thanks peter
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Post by sumgai on May 16, 2006 23:29:31 GMT -5
Peter, Then by all means, do as John and I have suggested and try it out! If you don't stray from the path we've outlined, you should be OK, at least for testing purposes. Obviously this is not a good long term solution. If you're on a budget, you might consider stripping the chassis out of the combo, and just using it that way. You might buy or build a closed-back cab, and putting the speakers into that. Or, here's a thought..... eBay the combo amp, and use the shillings to buy a cabinet filled with speakers. Unless you're married to the Marshall. Then you'd better start saving for a new speaker box, eh? ~!~!~!~!~ I've seen only one Carlton in my career, wasn't much to it, but it looked nice. Sounded about average, but the owner didn't want to spring for new tubes, which may have been the reason for the so-so tone. If you feel that you got a good value, then we're happy for ya! HTH, good luck! sumgai
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lenaghans1
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Post by lenaghans1 on May 17, 2006 6:24:59 GMT -5
sumgai do you know if i could disconnect the speaker cables from the amp in my marshall combo and solder a guitar input onto the speaker cables going to the speakers.the valves in the carlton amp are not ordinary valves they are smooth tubes and the inside of the tubes is completely different from valves
thanks peter
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Post by wolf on May 17, 2006 13:46:51 GMT -5
Please forgive this rather off-topic posting ... but I just couldn't resist. The topic itself seems like the title of an old TV show: "Head Through A Combo" In tonight's episode of "I Love Lucy", in an effort to sneak into Ricky's band, Lucy gets her head stuck in an amplifier. Hijinks ensue. [repeat] And welcome to the board lenaghans1
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Post by sumgai on May 17, 2006 14:06:42 GMT -5
Wolf,
That's funny, I was thinking more along the lines of "Tonight Lucy gives good....."
Oh. Never mind. </Latella>
sumgai
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Post by sumgai on May 17, 2006 14:20:52 GMT -5
Peter, Sorry, I always catch up all the way to the end before I reply, and the thing from Wolf was just too good to pass up! ;D That's why I answered him first, hope you'll forgive me. <still snickering> I'm under the impression that John and I have both told you to remove the speaker cable from the Marshall amp chassis before you plug in the Carlton, so now you're asking it it's OK to do that? Why, yes, it's more than OK, it should be done. I've said that in a pinch, if you forget to do that, on a valve amp it won't hurt (with the Marshall amp off), but on a solid-state head, no way - the speakers must be unplugged before hooking up the Carlton. And your first post states that there already is a jack on those wires, even your second post says that the soldering job is alright. So, do you want to replace that jack with a better one, is that what you're asking here? That's fine, so long as I've interpreted your request correctly, that's all. In short, yes, you can remove the cable from the Marshall chassis, and then solder on (another?) jack to the cable so that speakers can be hooked up to the Carlton head. If there is a jack already present, and it doesn't look so good, then take it off before putting on a new one. And be sure to use tape to insulate the protruding bare terminals and wire ends - you don't want to be shorting anything out here, the power involved can cause some pretty impressive sparks, not to mention some rather undesireable repair bills. HTH sumgai
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lenaghans1
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Post by lenaghans1 on May 17, 2006 16:12:07 GMT -5
sumgai what i was trying to ask you was if i could use the input jack from a guitar for this purpose.i think wolf is watching too much tv.
thanks peter
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Post by sumgai on May 17, 2006 20:55:59 GMT -5
Peter, Wolf is in another country, and lives in a different culture over there. Better let him maintain his current standard of living, or else there'll be trouble in NutzVille. ;D You keep referring to a guitar input jack. I know you don't want a lecture, but it'll help if you use the same terms we use, and when you ask vendors for the part(s). A guitar cord (or cable) plugs into a 1/4" jack (say it as "quarter inch jack"). This is a universal part, used for both input to an amp, and output from an amp. There are other connectors used for inputs (XLR), but those are rare on a guitar amp (more for PA stuff). There are also new-fangled speaker connectors (Neutek, I think), but they are rare, and so far, I've only seen them on very high-powered amps. For your purposes, yes, the same 1/4" jack from the input of an amp can also be used for the speakers. However, many amplifiers built these days, expensive and cheap ones alike, use jacks that are meant to be soldered right onto the printed circuit board. These parts would NOT be a good bet for speaker use. Not that they would make your tone bad, they just wouldn't hold up for very long - they need the strength of the chassis and the circuit board to hold them together - they're built very cheaply, and have no strength of their own. What you want is a Switchcraft 1/4" jack, similar to this one: 1/4" jack. That part is expensive from WD, you should be able to find it for half that, perhaps even at Radio Shabby, if you have one of those handy to your location. But that is the most reliable part you can get your hands on for this purpose. HTH sumgai
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lenaghans1
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Post by lenaghans1 on May 18, 2006 5:48:43 GMT -5
i want to desolder the jack of my guitar,solder it onto the speaker wires and see if the head works with that.wolf answered a few questions about wiring for me on the old board.
peter
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Post by wolf on May 18, 2006 9:38:22 GMT -5
lenaghans1 In a way, sumgai is correct - my "residence" is cyberspace. Also, I'm glad that you remember that I sometimes can make some useful postings as opposed to my occasional romp into frivolity.
It seems a lot of work to desolder your guitar jack just to see if it works on the speaker cabinet. You should actually buy one. Even at Radio $hack the price couldn't be too ridiculous.
As far as using a 1/4" jack for the speaker connection, I know some amps already use those. However, if it were me, I'd use something a little more substantial considering the rather high wattage of an amplifier / speaker combination. Also, the idea of using a 1/4" jack to also serve as the "switch" for the speakers seems seriously underrating the power requirements. I mean, you could tow two cars with a clothesline (well several runs of it back and forth) but is this the best way? And I doubt your guitar jack would have any switching capablity. If you mess up a guitar's wiring, the guitar doesn't work. If you mess up an amplifier's wiring, connections, etc, the results can be disastrous. Something to think about anyway.
Yes, maybe I watch too much TV but I learned all the above information from an episode of "Mannix". ;D
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Post by UnklMickey on May 18, 2006 14:16:14 GMT -5
...my "residence" is cyberspace.... Wolf, i guess if i lived in New Jersey, i wouldn't admit it either. (JUST KIDDING!) Peter, it's looking more and more like there might be a communication gap between the doctors and the patient here. do you (as John suggested) already have a MALE plug on the wires going to the speakers, and a FEMALE jack on the chassis of the Marshall combo amp? and the problem is, you can't connect the 2 MALE plugs together. (don't even go there Rune!) if that is the case, the easier way to connect the speakers to the Carlton head, would be to buy a FEMALE to FEMALE adapter. then you would simply plug the end of the cable connected to the Carlton and the plug from the speakers into the adapter. no soldering required. and it's all easily un-do-able. just disconnect the plug on the speaker wires from the adapter, and re-connect it to the jack on the Marshall. if you DON"T have a jack on the Marshall's chassis, and a plug on the end of the wires going to the speakers, could you please describe how the wires connect to the chassis of the Marshall combo? that might clarify things for us, so we can write a proper prescription. thanks, unk
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lenaghans1
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Post by lenaghans1 on May 18, 2006 20:58:18 GMT -5
unklmickey my marshall combo is an old amp.there is 2 wires coming from the speakers going into the amp chassis .they are probably soldered to the board. somebody has cut the wires half way down and add a female input socket.i have tried a lead from the head to this socket but dont get any sound.wolf it would only take a few seconds to desolder the jack from the guitar.its only to try it out quickly. to make sure the amp is working before sorting out a cab.we dont have any radio shacks over here in england.i would have to go to a guitar shop.
peter
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Post by wolf on May 18, 2006 23:25:35 GMT -5
Okay it's time to make some graphics so we all know what the heck we are talking about. Is that roughly the way the combo amp is currently wired? (Yes I know it is a twin speaker amp but the drawing should suffice for this discussion).
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Post by UnklMickey on May 19, 2006 8:43:32 GMT -5
hey Wolf,
i'm gonna turn this one over to you.
i'm glad to see you getting back into the mix again.
before i go, i want to leave one last thought.
maybe the guy who added the jack, but in a switched jack.
so that the jack disconnects the combo's speaker(s) and the output of the amp goes (through the cable that gets plugged in to jack) to an external cabinet only.
that would explain:
"i have tried a lead from the head to this socket but dont get any sound."
when anything is plugged into that jack, the only connection would to the output of the Marshall.
(EXACTLY what we DON'T want!)
just a thought.
take over Wolf.
unk
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lenaghans1
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Post by lenaghans1 on May 19, 2006 17:03:19 GMT -5
wolf that is the way it is wired thanks for your help
peter
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Post by wolf on May 19, 2006 17:07:28 GMT -5
Hi unklmickeyThere are many reasons why I haven't shown up here as much as I used to. I do work a full-time job and I spend a lot of time working on my website (which includes much more than guitar wiring info). But be that as it may (and I doubt if it ever was), here is a sllightly modified drawing. The dotted gray line indicates that the "switch" is actually part of the jack. When hooked up this way, it works as unklmickey has suggested - when a 1/4" plug is inserted into the 1/4" jack, the speakers are shut off and the jack serves as an amplifier output instead of a speaker input. ******************************************************** Okay, I just modified my modified drawing and now we have this: Wired in this way, if a 1/4" plug is inseted into the jack, the speaker stays on and the amplifier is off. Maybe I'm a little too cautious, but I'd feel a lot better if both wires were switched and a real switch were used instead of a flimsy 1/4" jack.
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Post by sumgai on May 20, 2006 16:15:41 GMT -5
Peter, In my previous post, I linked you to an image of a standard high-quality jack. I must have had my head inserted in a non-sunshine-capable orifice that day.... Sorry, but the following link points to what I would consider to be the proper jack for your desired application. It is fully enclosed, so it can't short out against anything else, and you can more easily grab it to disconnect the Carlton head from the speaker. Inline Mono JackNow, a question. On your Marshall combo, are the speaker wires mounted on a plug that inserts into a jack on the chassis? Or do they enter the chassis directly through a hole, probably with a rubber grommet? If the answer is 'through a hole in chassis', then what Wolf has said is your best bet, albeit his last note echos my own sentiments - depending on the small contacts of a jack to switch on or off a circuit is not a good thing. If your answer was 'there's a plug on the end of the speaker wires', then skip the switch business, and just get in the habit of unplugging the speaker from the Marshall chassis when you hook up the Carlton. In fact, I would go one step further. I'd use the above inline jack, and another plug, and make up an 'extension' cable. That new cable would go directly from the Carlton head to the plug on the speaker wires. In this way, you wouldn't have to install an extra jack at all, and you'd be forced to disconnect the plug from the Marshall. That would ensure that you've dotted your i's and crossed your t's. HTH sumgai
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lenaghans1
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Post by lenaghans1 on May 20, 2006 19:09:44 GMT -5
sumgai i dont know how to do a drawing and post it,i will try to explain the wiring.if you are looking into the back of the amp. looking at both speakers you have 2 solder points on each speaker top and bottom.on the left speaker top solder point you have a red wire going to the bottom solder point on the right speaker. on the left speaker bottom point you have a black wire going to the top solder point on the right speaker.then on the top solder point on the right speaker you have a black wire going to the left solder point of three solder points on the bottom row of the input jack.on the bottom solder point of the right speaker you have a red wire going to the middle bottom row of the input jack. the bottom middle and bottom right solder points are wired together.on the left top solder points of three on the input jack you have a black wire going straight into the chassis.on the middle solder point which is soldered to the top right point of three solder points on top of the input jack you have a red wire going into the chassis i know this like a puzzle. it was hard to explain after a few drinks.i think if you read each piece bit by bit you may work out
thanks peter
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Post by JohnH on May 20, 2006 19:24:28 GMT -5
On the other hand, one must never power up a solid-state amp without a load. Doing so is guaranteed to pop the output transistors in a hot hurry. sumgai Question for sumgai - what is the mechanism by which a transistor amp suffers when powered up with no load? In my youth I blew up several transistor amps, by inadvertently causing a short circuit. Fortunately I have not had experience of one exploding due to open circuit output however. In fact, I recall circuits where the output would be disconnected by a relay for a couple of seconds to avoid the initial thump as it powers up. I had another where the bias current through the output transistors got set by a preset pot, which was adjusted while powered up without a load on the output. John
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lenaghans1
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Post by lenaghans1 on May 20, 2006 19:27:44 GMT -5
i forgot to mention the input jack that somebody has soldered to the wires looks like a proper input jack from an amp.it has the round plastic screw of bit on the end.in my last post you would be looking at the jack with the screw of piece on the left
peter
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Post by sumgai on May 21, 2006 16:44:51 GMT -5
John, It might be said that there are two design eras of solid state amps, or perhaps, two schools of thought. Almost always, there is a load resistor in the near-ground leg of the output xsistor. But some early amps put that resistor in the output line (to the speaker), ala the old tube days. Turned out that this plan wasn't a good one after all. Quiescient currents within the output device itself were enough to cause what we'd recognize as "ground loops", but they were actually current flow loops in the supply rails. With no load on the "other" side of the supply (no speakers hooked up to act as current limiters), puff went the junctions. Moving the resistors to the near-ground side worked a lot better, but that's still suspect when using high-current output devices. Many a time there are other protective circuits built in to protect against these kinds of problems, you noted one, the power-on delay relay. That's because in the great majority of cases, the power supply flows through the speakers themselves on the way to the output devices. (!) Which is why, for the most part, it's a prudent thing to simply say, "no load is a no-no". No longer is this an absolute, iron-clad guaranteed thing, but it sure beats taking a chance, doesn't it? sumgai
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Post by sumgai on May 21, 2006 16:54:38 GMT -5
peter, Your description was sufficient, your speaker cables go directly into the Marshall chassis. In this case, I'd follow Wolf's advice, but I'd go so far as to remove the current jack (and it's not an input jack, it's just a jack), and replace it with something of higher quality. The part you described is of very low quality, and IMO, is nothing more than a malfuntion on the hoof, just waiting to ruin your day. Since they don't make "inline switching jacks" like you need for this job, settle for the switching version that Wolf shows you. (It looks almost identical to the first link I gave you, several posts ago.) Tape that up good to prevent any shorts, but leave enough room for the switching mechanism to work freely. Wolf has better diagrams than I do for this purpose, I'm sure he'll make a more detailed one for you, if you ask him nicely. HTH sumgai
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lenaghans1
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Post by lenaghans1 on May 21, 2006 21:20:55 GMT -5
i have already taken the jack of.i solder a jack from one of my guitars onto the wires going straight to the speakers of the amp but got no sound.should this work or do i need a switch type jack you have mentioned.i dont know if the amp is in working order.the person i bought it from sell a lot of different things.he said he tried the amp i dont think using a guitar.he said if you knocked the amp you got a crackle through the speakers.i dont know what kind of speakers he used.does that mean the speakers were getting a signal from the head.
thanks peter
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Post by sumgai on May 21, 2006 22:24:41 GMT -5
Peter, Which amp was not working, the Carlton? Or the Marshall? The above statement doesn't make that clear.
Alright, here we go, back to Square One:
1) Does the Marshall amp work with its own speakers?
2) Even after you took out the 'extra' jack?
3) Did it work before you took that jack out?
sumgai
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Post by wolf on May 22, 2006 0:52:10 GMT -5
If the jack did any switching, then there should be a "missing" section in one of the wire runs from the amplifier to the speaker. By the way, lenaghans1, could you at least make a crude drawing of what you are talking about? I use MS Paint - probably the least sophisticated graphics program - but it can be useful for this discussion.
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lenaghans1
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Post by lenaghans1 on May 22, 2006 10:16:27 GMT -5
sumgai the marshall combo worked.i never tried anything else in the added input socket before i tried the carlton head.wolf i dont know how to use those paint programmes.i have drawn a picture of the wireing i hope you can see it.all i need is a wiring diagram of wiring from the speakers to an input jack,and anything else i need to use.so i can use the carlton head with it.it dosent matter about using the amp part again
thanks peter
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Post by wolf on May 22, 2006 10:57:48 GMT -5
lenaghans1 So you do not want to use the Marshal combo amplifier at all? If so, I'm guessing that you want to use the Marshall combo (speakers and cabinet only) and plug the Carlton head into the speakers? To make things neater, could you remove the Marshall amp and squeeze the Carlton in its place? (That has nothing to do with the wiring - it's just a suggestion.) So, it seems if you just want the Carlton hed going through the combo speakers, that should be quite easy. What kind of output jack does the Carlton head use? Is it something like a 1/4" guitar cord jack? This wiring could be a lot easier than you'd think.
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