#1
Is it possible to use the external speaker output of my combo amp to plug straight into a 8-track digital recorder, thereby benefiting from the EQ and forgoing the use of my shitty mics. The manual of my amp says that the external speaker used should have an impedance load of 4 ohms in order to avoid damage. I looked into the manual of my 8-track and couldn't find anything relevant.
Is it safe?
EDIT: OK, found out that my 8track should be able to take it (has "400kW or more" - the W was the ohm symbol). But would it be safe for the amp?
Last edited by Lrn2play at Sep 27, 2010,
#2
No. Don't ever try this. Why? Not only will you damage the amp, but you'll also damage the recorder. The external speaker output is a high level output. The input of your recorder is low level.

400kW is 400,000 watts. That's a lot. That's more than most radio stations transmit at their antenna sites. It's A LOT of power. If you ever fed 400kW into your recorder, you best do it from afar. I guarantee you that you're in for a spectacular light show. The input level to your recorder is on the order of less than a volt. The output from your amp is on the order of several volts. Never shall the two mix.

Edit: Actually, I think all US radio stations have a max output of 100kW. If the W is the ohm symbol on your recorder, then that refers to the impedance. Still, not a good idea to connect your amp directly into your recorder. Not unless you need a new amp and recorder.
Last edited by KG6_Steven at Sep 27, 2010,
#3
No.
The manual of the 8track was what had the impedance of 400kW. I'm looking at an online manual right now, for some reason its slightly different, but under the specifications it says:
Input impedance:
1.5k Ohms (MIC/BAL)
:40k Ohms or more (LINE/UNBAL)
:500k Ohms or more (Guitar/ UNBAL)

those parenthetical notations being the mode in which the 8track is set to record in. So I would put it into the guitar mode, even though the 1/4" cable going into the UNBAL input is coming from my amp, not a live guitar.

My amplifier however, only asks that when using the external speaker output, "A total speaker impedance load of 4-ohms should be used to avoid damage to the amplifier."

So if anything the problem would not be too much power flowing from the amp to the 8track, but not enough to match the high impedance of the 8track.
But I'm not even sure if that would be an issue threatening the health of each device rather than an unusually dim recording volume, that could be adjusted with the Trim setting on the digital 8track.
Last edited by Lrn2play at Sep 28, 2010,
#4
I know that the 8track (its the Fostex mr-8) has the compatibility and function to have microphones connect to external preamps prior to reaching the mr8, and essentially thats all I want from my guitar amp - to use the preamp head piece of the combo as a preamp EQ for my guitar.
The mr8 manual even has a diagram-picture of a guitar plugged into a preamp plugged into the multitrack, but it is only a small, one of those little soundboard, preamps. So there is a missing implications here somewhere...