A friend of mine's stupid idea, curious as to result...

[cbc459]

The bassist in my band wants to experiment with home recording, but has to go the DI way because of noise concerns. Anyhow, his amp only has 2 outputs, a 4 and an 8 ohm. He was asking what would happen if he were to plug this output into the line in of his M-Audio interface... 4040 I think it is. I'm pretty sure this wouldn't be a terribly good idea, but I don't rightly know what would happen. How strong is a signal coming from these outputs?

[Phillystylec]

it will fry either the amp or the maudio thing. You need a speaker simulator if you are going that route. I hear good things about palmer's.

A pod would be a good way to go.

[cbc459]

My advice was to use the instrument input of his M-Audio, and forego the amp altogether, but he seemed intent on plugging his 4 ohm output into the line, and I was wondering what exactly would happen so I could discourage him from this stupid thing he wants to do. How would it fry the amp?

[Phillystylec]

The amp output is for connection to a speaker with either a 4 or 8 ohm load. the audio interface doesn't provide that kind of connection. I am sure someone else here knows the technical reasons. Maybe the amp has a recording out?

I think the direct in option is your best. You can record a dry signal and then use amp sims on it to tailor to your liking.

[Phrygian]

Originally Posted by cbc459

My advice was to use the instrument input of his M-Audio, and forego the amp altogether, but he seemed intent on plugging his 4 ohm output into the line, and I was wondering what exactly would happen so I could discourage him from this stupid thing he wants to do. How would it fry the amp?

Amps need proper load relief. You can damage an amp head just by having it on while the cab is unplugged. I don't know the technical jargon behind it (my Dad could explain better, he's an electrical engineer) but I just know that he's always told me that an amp head needs to be plugged into a cab if you're going to turn it on. The m-audio will not give it the relief it needs.

Phillystylec made some good suggestions. Your buddy can also try going direct into the maudio like you suggested.

Personally I DI into an API 512c into a Distressor and get fantastic results. I also have a Sansamp PSA-1 and Line 6 Pod XT Pro (with the bass patches) and both sound good. The PSA-1 is awesome actually...especially the SVT settings.

If he doesn't want to spend much more money but wants a good sound, tell him to pick up a Sansamp Bass Driver and go direct into the maudio. I have a buddy who swears by the Bass Driver for his live and recorded sound and it seems like a reasonable way to go on the cheap.

[drewharris]

May I ask why he wants to do that? I'm assuming we're talking about the speaker outputs on the amp? Someone please correct me if I'm wrong but wouldn't those be entirely too loud and unusable as they're a fully amplified signal intended to power a speaker cabinet? Is there not any sort of direct out or preamp out on the amp?

[Phillystylec]

I know that on all the tube amps I own the manual says only to follow the correct ohm ratings when connecting speakers to the amp or the amp might fry.

Maybe someone can give us the technical explanation for why it would fry. I would like to know, I know just not to hook anything up to the speaker out except speakers.

[Phrygian]

Oh and this may be only for tube amps. Again I could ask my Dad.

[Phrygian]

I did a quick search online and found this:

A tube amp must have a load connected to the speaker output whenever there is a signal applied to the power stage. The load can be a loud-speaker, a resistive / inductive power attenuator, or a combination of both. It is only possible to operate a guitar amp without a load when you are using the preamp stage alone and no signal is being fed to the power amp.

Using a tube amp without a load is SUICIDAL to the amp. You can arc the output tube sockets, short the power tubes, burn the screen supply, damage the filament supply of the power transformer, and fry the output transformer in minutes. I've seen printed circuit boards burst into flames!

Before ever using your amp without a load, connect a loud-speaker to it first. If you hear any sound through the speaker then you must leave the speaker connected (or use a power attenuator). If you are sure that there is no sound then you can remove the loud-speaker.

It is much safer to leave the speaker cabinet connected at all times just in case someone turns up the master volume or FX return to the power amp.

[Jim Kerr]

DO NOT LET HIM DO THIS!!!!! A 4, 8 or whatever Ohm SPEAKER OUTPUT WILL FRY HIS INTERFACE.......FRY!!!.......FRY!!! and DAMAGE TO HIS AMP IS POSSIBLE!!!...DAMAGE!! Now you know. If you want to know why look it up. There is a thread here that has QandA and its called something like "questions to things you should already know the answers to but don't"

Think of it like this. Attach a drinking straw to a fire hydrant nozzle. With the Hydrant off try to drink from it. Now.. while still trying to drink have your friend turn the hydrant on...full BLAST!!....understand.

[KingDaddyO]

Not to put too fine of a point on it but everyone's warnings are absolutely correct -- stikeDO NOT DO THIS !!stike.

Your friend will most definitely destroy his cute little m-audio thing, with the brutally huge power output of his amplifier. And depending on how long it takes for m-audio to die, or your friend to react and shut off his amp, he might destroy that as well.

If he is interested in interfacing these devices properly, he should either plug into the instrument input of his m-audio if there is one (not the line input, although that could work), or get a DI interface, or build one of his own. Here are some helpful links:

Speaker signal to line level
Converting from guitar level to line level - Electronic Circuits Projects Diagrams Free

[joelpatterson]

Hell, let him do it... some people just need to learn the hard way.

[TheSoundFella]

Originally Posted by joelpatterson

Hell, let him do it... some people just need to learn the hard way.

Heh ......I found humor in your evil ways

[Sounds Great]

Originally Posted by cbc459

The bassist in my band wants to experiment with home recording, but has to go the DI way because of noise concerns. Anyhow, his amp only has 2 outputs, a 4 and an 8 ohm. He was asking what would happen if he were to plug this output into the line in of his M-Audio interface...

Are you sure he's not the drummer?

[slaves666]

I have a short story to share......

The band I used to share a rehearsal with were looking for a recording solution. I use a Roland 1880 in my room to track demo's and pre-prod for bands. I found them a great deal here on one....and they bought it.

About 2 weeks after getting it, they asked me for help learning it....I told them everything they needed to know, and since I pointed them in that direction, I felt obliged to give them help anytime.

I go in one day to help them, and they tell me that 2 inputs aren't working. I figure a routing problem, so I look in the menu, looks fine....check the mic cable, and mic, through the PA, and it works fine. Then the guitar player chimes up and says "could it be anything to do with the fact that I had it plugged directly into my amp?" I say how so, since I can see he has a small combo. He says " I plugged it into the 'external speaker' jack" I was like, "are you serious?" He's like "yeah." I then asked why he had 2 inputs that didn't work.....he says " well it didn't work the 1st time, so I tried another input....when the 2nd didn't work, I figured I'd call you cuz something must be wrong with the machine."

Now let me finish the story with the fact that the band are all late 20's early 30's guys, and the guitar player actually has a VS880 at home, so he knows roughly how it already works.

I hate stupid people.

[dbbubba]

Now you know how I feel about the large majority of people I know who own, use or touch gear!

I is like taking the wings off of a Boeing 757 in order to make a fast bus.

Like Joel said, "Let him do it."
He'll do it once and he'll learn something.
Well, the guy that ruined TWO inputs on the Roland 1880 didn't learn anything with the first input.

[jmarkham]

Originally Posted by cbc459

The bassist in my band wants to experiment with home recording, but has to go the DI way because of noise concerns. Anyhow, his amp only has 2 outputs, a 4 and an 8 ohm. He was asking what would happen if he were to plug this output into the line in of his M-Audio interface... 4040 I think it is. I'm pretty sure this wouldn't be a terribly good idea, but I don't rightly know what would happen. How strong is a signal coming from these outputs?

Why doesn't he get a SansAmp or a REDDI? In particular, the REDDI almost
obviates the need for a cab.

jeff

[turnstile]

Originally Posted by slaves666

I hate stupid people.

I was a staff engineer in a studio in Chicago sometime back. When an engineer would come in I would assist. Anyhow, the engineer was setting up for tracking guitars so they had the cabinets in the live room and the heads in the control room. We had dedicated tie lines for this sort of thing. Anyhow, I had to run to another of the control rooms to get some things and I come back and the smell of buring caps/resistors was wafting thru the air.

The "engineer" decided to use the patchbay of the console to reach the jack panel out in the live room. He totally burned the entire channel strip! This was on a Neve VR. Intelligent.

[sluttygearhere]

If he is determined to use the amp outputs then I would suggest getting a radial JDI as I believe it is built to handle signals like this and transform then to Mic line signals while keep a load on the amp. If I am wrong on this someone please correct me, but I have just recently bought one for someone else and I thought I remember reading in the manual about this.

[Froombosch]

What still happens a lotois that some idiots use microphone cable for speakers. When your playing loud they the microphonecable can melt.... and the wires may connect. When that happens it will FRY the amplifier. There are little amplifiers that can take that kind of abuse.