Line Out Box

[MetalUpYerEye]

Hi again. I have a 120 watt SS amp that I usually run into a 4x12 cab but i'd like to use it for recording. Unfortunately for me it doesn't have a line-out or headphone jack to use for direct recording and mic'd it sounds like garbage. I read a little about this "line-out box" by Bancika (http://storm-software.co.yu/diy/index.php?project=zogzog) I have a few questions...

Does this require that light bulb? Does it require the 8ohm 5W resistor? What exactly is a 1:1 audio isolation transformer and what does it do?

I'm assuming that since there is no power supply in the schematic that none is required for this project. Is there any more information for this project and/or other projects like it?

Thanks a lot.
J

[Pedal love]

The light is there to show if the the amps output, is plugged into the input of the device. The resistor doesn't necessarily require the same resistance as the resistor shown. It depends on the impedance of your cabinet. If you are not sure of the impedance check out the speaker wiring. Just like resistors parallel speakers divide, series adds impedance. A 1:1 transformer doesn't really change the signal strength,  so its there to isolate the device's input voltage, from this line output.pl

[Joecool85]

You can just use a couple resistors and a jack on a solid state amp, like this:

http://www.singlecoil.com/docs/out.pdf

[bancika]

actually, bulb is there as simple attenuator. Read more on www.valvejunior.com, you must ommit it because I don't think there is 120W bulb with 12V voltage. As for resistor, it's not necessary if you are using solid state amp. Tube amp mustn't be run without load on output transformer. If I forget to plug speaker (or just don't want to) resistor acts as dummy load. As for transformer, it's just audio isolation, to eliminate connection between ground of amp and ground of device that line out goes to...or it's just how I understood it
Cheers

[Pedal love]

actually, bulb is there as simple attenuator. Read more on www.valvejunior.com, you must ommit it because I don't think there is 120W bulb with 12V voltage. 

Thanks, I didn't read or check it closely. Yes I would eliminate it. Resistors are the way I would go.

[darron]

if it sounds bad mic'd, then you are using the wrong mic. when you are doing recordings you'll sometimes try 10 different mics before you find something that you like. that's assuming that it sounds good raw.

if you wanted to do a line out, couldn't he simply put a switched jack that will take the signal from the preamp before it gets to the amp? i would think that that would give a better noise to signal ratio? you'd have to DI it after that anyway if you want to use it for your recordings.

[d95err]

if you wanted to do a line out, couldn't he simply put a switched jack that will take the signal from the preamp before it gets to the amp? i would think that that would give a better noise to signal ratio? you'd have to DI it after that anyway if you want to use it for your recordings.

Yes, but then you'd have to modify the amp. With an external box, you could leave the amp as it is.

The simplest solution of all would be to simply buy a Behringer GI-100. It's both a DI-box and a speaker simulator. You can plug the speaker out of a solid state amp directly into it. It's probably cheaper than a DIY-project too, but then again DIY is more fun 

[MikeH]

I agree with Darron.  If it sounds good to your ears but like crap when you record it, you need to revaluate how you're recording it.  Whatever mic, medium, production settings you are using are no good for the particular setup you're trying to record.  In my experience a direct out tends to give a sound on tape that's far worse than any microphone.  Unless it's a modeler (Line 6, etc.) or being run through a simulator that's meant for direct recording.  If it's some kind of high-wattage, solid state, Randall or Crate you'll typically find the direct sound to be hiddeously shrill.