Can I do this? Amp combination...

[mot]

Hi all,
This might sound like the most awful thing ever to some but bear in mind that I've already done it, just wondering if it will explode or electrocute me!

I have a little 10w Prime amp that I absolutely love the sound of but it's far too quiet for using live so I had the thought of buying a bigger amp and trying to connect it up in some way. I know there are undoubtedly better ways of doing this but here's what I've done anyway:

I bought a dirt cheap old 60w Crate G60XL which has a Celestion G12M70 speaker in it. First I just tried connecting the Prime amp head directly to the Celestion speaker but it didn't seem to make it much louder.
After trying out a few other combinations of various leads going various places what I ended up with was this:

I have my guitar going into the amp head of the Crate with a jack lead going from the line out on the Crate to the input of the Prime amp, with the Prime amp connected directly to the Celestion speaker.

It sounds great (to me!) and means I have loads of control over the sound with two amps to play with (and two spring reverb units!) but I don't know anything about the magic of electricity so I'm just wondering is this a very stupid thing to be doing? Is there a danger of blowing the speaker and/or either of the amps? Or of setting the house/venue on fire or anything?!

[DrGonz78]

Without looking at the schematic it would seem to me that a line out is another name for preamp out. So you are basically taking one amps preamp line level out into the input of another amp preamp. The output is through the 10 watt amp and will not blow out the higher rated speaker. So in other words if it sound good to you then it is good. Does it sound louder? Perhaps but not because you have a 60 watt amp output. It is just a more crafted signal input into the small 10 watt amp w/ a decent speaker. You are amplifying one preamp with another then pushing it only through 10 watt output. Much like people use a front end like Digitech or Line 6 pod preamp processors and put them in front of a clean channel amp.

What do you do though when you travel with the amp to play somewhere? If the prime amp has one of the speaker's terminal accidentally disconnected while playing that will probably blow out the amp's output chip. As far as electricity is concerned a line out is safe to plug into another amp or mixer. If you were to plug a speaker out into a line level input of an amp... Well just avoid doing that and your golden!

[mot]

Thanks for that. It does sound a lot louder alright. I'm going to actually build both pre amps into the speaker cabinet, it'll look a bit mental but that's fine!

[Kaz Kylheku]

You're using your Crate head to boost the signal.

Since that is working for you to overcome whatever you think is wrong, it basically means that your 10W amp doesn't have enough gain in its preamp for your tastes.

Lugging around an amp head just to use its preamp as a booster is silly.

You could just use a small overdrive pedal, the 10W amp, and the speaker cab.

[mot]

Actually it's not the gain I was worried about at all it was mostly a lack of volume with the clean(ish) tone of the prime amp. The way I have it set up now I have loads of different knobs to twiddle and two different spring reverb units (which sound nuts when combined).
Basically I think it sounds much more interesting then an overdrive pedal and seeing as I'm actually going to have both amp heads in the one box I won't be lugging anything anywhere, and, also, I'm damn proud to be silly!

[mexicanyella]

Does the 10-watt Prime amp have a line out jack, or a headphone jack?

If you really like the tone of the Prime amp, but it's not loud enough, as your first post states, it would make the most sense to me to "slave" the Crate G60XL off of it. In that scenario, ideally you'd take a line level signal from the Prime's line out (if it has one) into the Crate's line in (or the return jack of its effects loop). The Prime becomes the preamp, bypassing the Crate's preamp, and feeds the Crate's 60-watt output stage and 12" speaker. It's not even that silly, if you just consider the Prime to be a slightly bulky effects pedal that happens to have a speaker in it. I do a similar thing using a Peavey Audition 20's line out feeding various other amps sometimes, and I am not silly.

Never. At all.

If the Prime does not have a line out jack, sometimes a headphone jack can work for that purpose. Or, possibly better yet, you can just add a line out to the amp. I haven't done that yet myself, but there are members here who can tell you the couple of different resistor values you need and how to connect them to the speaker wires. Here's one article on the subject:

http://www.rru.com/~meo/Guitar/Amps/Kalamazoo/Mods/ezlo.html

Joecool85 has mentioned on this forum that he added a line out kind of like this to a no-line-out Dean Markley practice amp; you might do a search for "Dean Markley K-20X" and see what you find.

[Roly]

If only the preamp output is desired the another place to pick up a signal for a Line Out is at the main volume control where it feeds into the power amp stages.  This also allows the main volume control to act as a Line Out level control to avoid (or force ) overload of the input stage of the other amp.

The speaker tap off idea works, but I have found problems with the speaker acting as a microphone and picking up the drummer (and we all know how hard it is to get a drummer to "turn down" ).

[Vitrolin]

I would go with the volume pot for line-out, you could use a buffer or jack-switch to silence the power amp when using the line out.

if you want to use the signal at the speaker wires disconnect it and replace it with a power resistor of equal value, mount it on a heatsink...and no drummer in your amp