Drive amp's own speaker from rec out?

[Rand524]

I asked the question the wrong way before (Koch amp question). With combo speaker turned off, what kind of "outboard" amp should I use to drive the combo's own internal 8 Ohm speaker from the amp's record out signal? Would a simple, say 20 watt amp with a volume control work? I would think that a clean amp that could just duplicate the record out signal - with whatever distortion it was carrying form the combo (tube) amp - and drive the amp speaker would allow me to listen to the amps own tone at lower volume. I hope that makes senss.

[stokes]

So you want to take your record out and plug it into an external amp and then put that amp into your speaker which is disconnected from the original amp?What is the output tranny on your combo connected to?If it is connected to nothing you will damage it.I am assuming this "Koch" amp is a tube amp,not familiar with it,though.If it is a solid state amp,I'll leave that to someone else,dont use solid state dont know enough about them to give any advice.

[Rand524]

It's a tube amp - 20 watts class A, 3 12 AX7s and 2 EL84s. They're made in Holland (www.koch-amps.com) and the Studiotone has a "power soak" with a single setting that turns the speakers off completely and a couple of line out (-10db) options off of the output stage- on plain and one with filtering that simulates center and off center mic'ing and different cabinets. So the outboard amp would use those as inputs and drive the combo. I've seen some fairly inexpensive solid-state bare bones amps/kits with volume controls in the 20 watt range - I just need a power amp so wasn't thinking of using a head or another guitar amp.

[stokes]

I suppose the power soak is taking care of your OT,so that'll be safe.So the record out comes off your output stage?So I take it you want to drive your combo hard and then attenuate it with the "external amp" back into your combo's speaker.I am not a fan of them,but wouldnt one of those power attenuators be simpler?I see Weber has a couple in the 75 to $100 range,I think the amp you suggest using will "color" the output more than you may want.You can see them at www.tedweber.com

[boyer]

Seems to me he's looking for a DIY solution to this problem, instead of buying an attenuator.
Not to mention, it sounds like the amp has modeling build in, and may not be available from the speaker out, and rather only available on the recording out. I'd have to see the schematic to be sure though of course.

As long as there is something (in your case the power soak, which is probably just a dummy load) connected to the OT to keep it from eating itself, you will be fine running your recording output to the input of most other amps. That -10 signal coming from your recording out should be fine for most amps inputs, and infact will probably need to be turned up about to 30%. Use your ears, and try to adjust for the least distortion.

You'll want to try to match the impedance of whatever amp you now use to drive your speaker. So if your speaker is 8 ohms, make sure you use an 8 ohm output on your amp.

Of course with an SS amp, it doesn't matter nearly as much as with a tube amp, but I still like to match to spec. when possible regardless.

Hope that helps.