Jump to content
Gibson Brands Forums

Amp Question


adlankj

Recommended Posts

So, I was thinking about changing the speaker in my combo amp (fender blues junior). I opened it up to look at what I'd have to do to replace the speaker, and I noticed the cable that plugs the speaker into the amplifier itself. It has a regular 1/4 inch connecter. I was wondering: If I connected this cable into the speaker out of an amp head, would I be able to use my combo amp as effectively a cabinet?

 

(note that I'm not talking about the input to the combo amp. I'm talking about the speaker cable that you connect to the amplifier itself, that you won't see unless you open the back of the cabinet.)

 

Thanks in advance.

Link to comment
Share on other sites

If I connected this cable into the speaker out of an amp head' date=' would I be able to use my combo amp as effectively a cabinet?[/quote']

 

Yes. Just remember not to turn the combo amp on as a tube amp should never run without a speaker load. I always unplug my amps anytime I am going to remove the speaker load for any reason. That way they cannot be accidentally powered up without a speaker load.

Link to comment
Share on other sites

 

Yes. Just remember not to turn the combo amp on as a tube amp should never run without a speaker load. I always unplug my amps anytime I am going to remove the speaker load for any reason. That way they cannot be accidentally powered up without a speaker load.

 

+1

Link to comment
Share on other sites

Can't give you a real good high tech answer - but electronically all the components in your tube amp are designed to work in harmony with the designated speaker load - usually 8 or 16 ohms. With that load removed the other components will react differently (and not in a good way). As I understand it this is particularly bad if the input receives signal (ie your guitar is plugged in and you start attempting to rock out) and not as bad if there is no input signal (ie you accidentally flip it on briefly with no guitar or speaker plugged in but quickly catch your error and flip it back off). I have done the latter a few times with no noticeable adverse effects. Hopefully someone with more knowledge can give you the technical reasons.

Link to comment
Share on other sites

OK. You have me snowed. What is he doing? Is he running a guitar chord from a jack on one amp to a jack on another amp? Or he is switching speakers inside the same amp? Of he is running two amps together (somehow?) Also can you make a bigger or better speaker change-out on a fender Eighty Five or a Kustom Smart 10 FX? Also can anyone define what "presence" and "limiter" and "gain" does on a Fender 85? Or do those items have any meaning to anyone other than Fender or Kustom? I notice that most guitar sales people have no idea what they do or how to set an amp on "clean" Does anyone have any idea why amps have to be so esoteric and why owners manuals say nothing about how to OPERATE an amp? Does any of this make sense to anyone?

 

What does "pre-amp out" or "line out" or "line in" or "Cd-tape in" do -- can you run things together at the same time? Like a drum machine into the guitar amp while playing a guitar? Or a microphone for a singer?

Link to comment
Share on other sites

A tube amp needs to have a load on its output. The AC current and voltage on the primary and secondary sides of the output transformer are directly affected by the load on the secondary side. The optimum conditions exist when the secondary (or output) side of the transformer is properly loaded. Some tube amps use shorting jacks for the speaker outputs. When there is no load connected to the speaker jack, the output of the transformer is shorted to ground. Now while this is far from an ideal condition, it will, for a short duration, prevent damage from occurring in the output transformer. It will, however, cause damage to most transformers if this condition is sustained for any extended period of time because too much current is being drawn from the transformer. When there is NO load on an output transformer, it attempts to develop more voltage on the secondary side. This can cause the internal insulation of the transformer to break down and high voltage arcing can occur causing shorted turns or open windings.

Link to comment
Share on other sites

OK .. so what they are talking about if balancing the load on the circuit. OK. I am fairly good with that. Especially the transformer part since we had similar problems in Sonar except they used capacitor banks to load up a charge before a ping so that chips circuits would not overload (the effect that an elevator or air conditioner has on a building bus (and an AS400). They are not talking about connecting to external speakers or amps.

 

PS -- the quote if from Greenspan (speaking to Congress) "I know you believe you understand ..." etc) Well living proof of the reality of the quotye is the mess we are in today. He told them (over and over ) that Fannie/Freddie were too heavy in paper assets and that the value of the paper did not come close to the value of the security (homes) .. and they did not understand what he told them.

Link to comment
Share on other sites

Thanks for the explanation. I'm working on this amp build and I fired it up last week and the only sound it makes is a low hum. I plugged it into a speaker in my fender combo (M-80), but I only unplugged one side from the combo. I'm trying to figure out if I fried my OT or if it's something else.

Link to comment
Share on other sites

This was a good thread. It inspired me to do some searching and reading on my (and other) amplifier features. ...some of which have been black magic to me since the 1980s (because if you turn them nothing happens)(which is MORE actually than the amp sales man knows). The salesman (then and especially now) says "this is popular." That's about all they know and I knew less yet. Over at GC the salesmen (plural) cannot get ANY amp to go on clean channel and so you cannot find an amp you'd buy at GC. They also say "this one is popular" but since there are 100 kids in there you think "popular with whom?" (cars that vibrate from boom boxes are also popular with them) If you go to a music store (normal) they are really a school band supplier and guitars mystify them too. Amps are black magic as well. So I did some reading and it looks like my Fender 85 is a decent amp (it works for me to be sure) but now I know the "presence" knob increases the high or treble frequencies (and is good for playing in a band) and the limiter knob supposedly limits the load on the transformer which is what KSB_Standard was saying. The bad thing about the Fender 85 is that the input jacks are junky (plastic) and need to be repaired a lot (which I knew) I looked for a replacement amp a while back and found they were all way too expensive and actually junkier than the Fender. HENCE I can see why you'd build your own. [in all, then, it is still very murky territory and getting a well made reliable amp is still more a matter of dumb luck than of smart buying]. But I will keep the Fender 85 since it will do my job very well and there are several shops that can repair it.

Link to comment
Share on other sites

This was a good thread. It inspired me to do some searching and reading on my (and other) amplifier features. ...some of which have been black magic to me since the 1980s (because if you turn them nothing happens)(which is MORE actually than the amp sales man knows). The salesman (then and especially now) says "this is popular." That's about all they know and I knew less yet. Over at GC the salesmen (plural) cannot get ANY amp to go on clean channel and so you cannot find an amp you'd buy at GC. They also say "this one is popular" but since there are 100 kids in there you think "popular with whom?" (cars that vibrate from boom boxes are also popular with them) If you go to a music store (normal) they are really a school band supplier and guitars mystify them too. Amps are black magic as well. So I did some reading and it looks like my Fender 85 is a decent amp (it works for me to be sure) but now I know the "presence" knob increases the high or treble frequencies (and is good for playing in a band) and the limiter knob supposedly limits the load on the transformer which is what KSB_Standard was saying. The bad thing about the Fender 85 is that the input jacks are junky (plastic) and need to be repaired a lot (which I knew) I looked for a replacement amp a while back and found they were all way too expensive and actually junkier than the Fender. HENCE I can see why you'd build your own. [in all' date= then, it is still very murky territory and getting a well made reliable amp is still more a matter of dumb luck than of smart buying]. But I will keep the Fender 85 since it will do my job very well and there are several shops that can repair it.

 

Yeah this is/was a good thread even though I sort of high-jacked it; then again, his question was answered. It takes the steam off of the political or racist threads - though those can be entertaining.

 

I started looking into building ever since surfpup posted a link to his new marshall 18watt clone that was a DYI amp kit. I want a Dumble amp sound and the only way I can afford that is to build it myself. Even though I'm trouble shooting my first (easy) build it has been fun and sort of a nice hobby to work on.

 

In case you didn't know, dumble started with Fender designs and took them to heaven - IMHO.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...