Did I ruin my mixer or soundcard?

used a tube amp for guitar

We’ve really been very very stupid. We have had the speakersoutput (110 watt WOW) a long while in the input from our mixer :p We recorded this way for around 2 months. The third line in channel of the mixer 's blown up. We think the rest still works but I’m not sure if the sound is that clean as it was before… We have a LEM mixer RD 82 FX and an EMU 1212m soundcard. But what can be happened with the rest of the mixer or the soundcard? When there is more damage would I hear it directly or can the damage be small. Other words: Damage is real big damage or no damage? :(

Ouch. You never want to connect the speaker output of an amplifier to a line-level device such as a mixer or soundcard.

Yes, you have probably damaged the mixer. It may be damaged “a little” on the other channels but I suspect you are OK unless you can hear a problem. Also the soundcard should be OK.

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We recorded this way for around 2 months


I’m surprised that you lasted that long.

If the amp is a valve/tube amp you have likely damaged that too. If it is a solid state amp you may be lucky.

I suspect you must have run at very low power levels to get this to work.

Sorry to be the bearer of bad news.


Mark

Plugging the speaker output of your amp into the line-in of you mixer runs a very high risk of destroying both your amp and mixer! Without actually seeing your equipment, it’s unlikely that anyone can tell you exactly what may be broken…

Do yourselves a favor… Instead of plugging your amp into your mixer, find a used POD v2.0 on eBay ($100-150?) and use it to record your guitar tracks.

Or buy a microphone.


:cool:Ebay - POD 2.0 listings

Quote (Mark A @ Dec. 14 2005,11:12)
Also the soundcard should be OK.

You think the soundcard stays oke?? Well if yes than the news is not too bad :p

Well I’m hoping that the soundcard was “protected” by the… that took the “full force” of the attack.


Mark

if your amp has an effects loop, that would be ok to take a line out to your mixer, but as stated before… speaker outputs and line inputs DO NOT MIX.
your amp’s speaker output is capable of many watts of output, while the input on your mixer is probably expecting more like a fraction of 1 watt…
If your amp is a tube amp, it requires a minimum ohm load of speakers, not having that allows too much current into its transformer and can fry it.

If your mixer still has some functioning channels, then your a very lucky to say the least. If it still works, keep using it I say. Although there is probably the possibility of a short causing bigger problems.

next time though, use the effects loop send, or preferably… MIC the #### thing. :) You can even plug the guitar directly into the board, won’t be ideal, but it’ll still be a lot better than the speaker output lol.

You can use an inexpensive direct box like this one in parallel with your speaker in order to connect to a mixer. Lots of folks use them so they can avoid the hassle of micing their speaker.

http://www.music123.com/Behringer-Ultra-GI100-i37156.music

Peace,
TrackGrrrl

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If the amp is a valve/tube amp you have likely damaged that too.


Sad but true…

Best case you might just need to get a tech to replace an opamp in the strip of the mixer that’s shot.

And yes, if the output stage of the mixer didn’t ‘redline’, the soundcard wouldn’t have gotten any damage.

I almost had a similar booboo one night at church.
I have a DSL 401, and the parralell speaker out is very close to the ‘emulated line out’. Sound guy plugged the line out cable into the red socket…
Lucky I had the amp on for 1 minute (still very low volume while tuning) when the sound guy said I must turn the amp down 'cuase it clipped the input of the mixer strip with the gain on 1 or something.

Checked the back and didn’t like what I saw.
He’s leaving the red jack alone now …

W.

First of all: as said, connecting your mixer to the spreaker output of a tube power amplifier just like that is a bad idea.

But having said that, the speaker output of that tube amp with the right speaker connected is the best source for recording that typical tube amp sound, without using a mic.

You need the speaker connected for two reasons:
1 - Without the low-resistance output load, the output transformer is going to act much like the ignition coil in your car. The voltages can get so high that the internal isolation fails —> sparking & short circuits. This can damage the transformer badly. And more of the amp, depending on the fusing.
2 - The speaker has a considerable feedback influence on the amplifier. You’ll miss that influence if you use the effects loop or if you use the speaker output with a dummy-load.

Even with a speaker connected you cannot connect the output directly to your mixer.
You can use a DI as suggested above or you can improvise one yourself with two resistors, attenuating the signal about 10:1 (for a 50W/4 Ohm output) to 20:1 (for 100W/8 Ohm).

Using a microphone will give even better results, but only if you do everything right.

Hansje omitted another important point: with a tube amp, if you play it with the speaker unplugged, you can damage it severely. I don’t understand the reasons for this, but I do believe the folks who told me.

Also, congradulations on confirming the predictions of Mac at audiominds.com. Earlier I asked him to go through the math to figure out just how dangerous this is, because I’d heard reports of folks doing it without any harm (and recommending it to others!) Based on typical components and designs for line inputs, he figured that the danger area begins around 100W, cranked. Of course, the usual tradeoff between time and power applies: the higher you crank it, the quicker it’ll fail and vice versa.

Note that this does NOT mean that with a 50 watt amp you’re safe! Watt values for amps are estimates, for one thing. I wouldn’t even do it with a 10 watt amp – it’s just not what the gear is designed to do.

But there’s a resistor in the input stages of a typical line input, and around 100W, the juice going through it would exceed its rating. Poof.

Now, when something goes poof, you have no idea what damage it can cause downstream. You could be lucky or not. It could damage other channels or common output circuitry, or even input circuitry in apparently unrelated parts of the mixer. And it could damage the soundcard, but I think your chances there are better. Or you could be lucky and the part that blew could have taken the power amp out of the picture (working like a fuse) and everything else could be fine. You’ll never really know.

There is a way to benchmark your soundcard, at http://audio.rightmark.com. It’s a bit technical, but might be worth a try. Any soundcard designed for DAW use should get an “Excellent” rating in all or most categories, with no categories worse than “Good”.

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Hansje omitted another important point: with a tube amp, if you play it with the speaker unplugged, you can damage it severely. I don’t understand the reasons for this, but I do believe the folks who told me.

Please reread my post above. You’ll find this point + explanation under 1.
Maybe I should have stated more clearly I was discussing damaging the tube amp here and not the pre-amp in the mixer.
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Also, congradulations on confirming the predictions of Mac at audiominds.com
This is less miraculous than you may think, as I’ve been having this discussion with Mac (and you!) a year and a half ago:
http://audiominds.com/forums/index.php?showtopic=428&hl=

Quote (hansje @ Dec. 15 2005,05:31)
You need the speaker connected…

1 - Without the low-resistance output load, the output transformer is going to act much like the ignition coil in your car. The voltages can get so high that the internal isolation fails —> sparking & short circuits. This can damage the transformer badly. And more of the amp, depending on the fusing.


Yup!

Oops, careless reading on my part!

Hah! hansje is an electro-geek! We have another onboard here! Vee veel take ofer zee VERLD!!! Bawahahaha… :D

TG

Quote (learjeff @ Dec. 15 2005,11:42)
There is a way to benchmark your soundcard, at http://audio.rightmark.com. It’s a bit technical, but might be worth a try. Any soundcard designed for DAW use should get an “Excellent” rating in all or most categories, with no categories worse than “Good”.

Learjeff, I’m ashamed, my english especially about this specific topic is not that good :O . But the advise you gave seems usefull. Can you explain in very easy english what you mean exactly? :)

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Learjeff, I’m ashamed, my english especially about this specific topic is not that good . But the advise you gave seems usefull. Can you explain in very easy english what you mean exactly?


I’m not Jeff (I suspect he’s sleeping), but I’ll have a go…

There is a tool here: Rightmark that can be used to test and measure a sound card. (Note: Jeff’s link was incorrect)

Jeff suggests that you use it to test your soundcard for damage.

The pages at that site are quite technical. Follow the instructions if you can translate them. If not, ask for more help here.

The results for your soundcard should be in the category “Excellent” or at least “Good”.

Does this help?
Quote (Mark A @ Dec. 16 2005,03:36)
Does this help?

Mark, Oh Yes great! Well I thought I understood Learjeff but I couldn't match it with the link...so I thought that I understood him maybe wrong. But that is a great test.When I conect that computer to internet I test it. Can't do it directly 'cause my pc with soundcard is upstairs (I use a laptop when i'm on internet) and I have to mess around with several wires... :D
Thanks, I'll let you know.

Thanks for filling in, Mark. And yes, the rumors are true, I do sometimes sleep!

Maria, no need to be ashamed of (or apologize for) your English, which is far better than my anything-but-English! I wish I could speak any other language half as well as you write English!

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Hah! hansje is an electro-geek! We have another onboard here! Vee veel take ofer zee VERLD!!! Bawahahaha…

Although this is wildly off topic, I cannot let it pass of course.

Being non-anglophonic by birth, I had to look up the word “geek”.
In wikipedia, I found a dozen meanings; at least half of these more or less accurately describing me.
But one was really dead-on:

A person who swallows live animals, bugs, etc., as a form of entertainment at fairs etc. This often included biting off the heads of chickens. The Geek would usually perform in a “geek pit”. This probably comes from the Scottish geck, meaning ‘fool’, in turn from Low German. (19th century.)

So I call out to whoever may be with me, down here in the geek-pit, and say:
If I’d bite off Diogenes’ head, would you have Alexander’s? :cool: