Ampeg svt6 pro blown

[Paula]

This is what happened... I was admiring how loud my sons cab was when he played his bass and I wanted to listen to my music just as loud - so - I connected my ipod to the head (ampeg svt6 pro) and it worked for 2 seconds, then it went dead - hasn't worked since.  Could someone give me a clue as to why this happened and how to fix it myself. (I've been quoted 400 bucks to repair it). I thank you in advance.

[Reggaebass]

Hi Paula and welcome 👍, how did you connect it 

[paul_5]

Oops. If you’ve gone straight from the iPod to the instrument input socket then you’ve probably had a positive loop and killed the amp due to very high frequency oscillations at full volume.

I’m sorry for your loss.

[Bill Fitzmaurice]

Did you check the fuse?

[Reggaebass]

5 hours ago, Bill Fitzmaurice said:

Did you check the fuse?

Bill, out of interest is it ok to to use a iPod, which is the same as a phone I guess, if it’s going through a interface into your amp, but it’s not good if it’s going straight into the input socket.  And are valve amps different 🙂

[Bill Fitzmaurice]

The source doesn't matter, and an interface isn't necessarily required. The issue is that the output of an iPod is probably at line level, about a volt. The output of passive pickups is closer to 1/10 volt, so an iPad could overload the input stage. That normally would only cause the sound to be very distorted, but if one's not careful it could pop something in the amp. If anything valves are less likely to suffer damage from a high level source.

[Reggaebass]

13 minutes ago, Bill Fitzmaurice said:

The source doesn't matter, and an interface isn't necessarily required. The issue is that the output of an iPod is probably at line level, about a volt. The output of passive pickups is closer to 1/10 volt, so an iPad could overload the input stage. That normally would only cause the sound to be very distorted, but if one's not careful it could pop something in the amp. If anything valves are less likely to suffer damage from a high level source.

Many thanks bill 👍

[BassmanPaul]

Take the amp to an Ampeg Service centre and get it repaired. 

Do the battery test on the speaker system to see if you actually blew the cabinet and not the amp.

If you don't know what the battery test is: connect a speaker cable to the cabinet. Connect the plug on the opposite end across the terminals of a 9V battery. If the cabinet is good you should hear a hearty thump from it.

Hey Paula that's a cue for a song! LOL

Edited March 19, 2021 by BassmanPaul

[agedhorse]

Running an iPod into the instrument input of an amp shouldn't damage it. I do it all the time as a test signal source.

[Lfalex v1.1]

On 20/03/2021 at 04:02, agedhorse said:

Running an iPod into the instrument input of an amp shouldn't damage it. I do it all the time as a test signal source.

I've tried it. Mainly to see how a cab was voiced with regard to full-range recorded music. 

I started with the device level at about 25%, gain at Zero, master at Zero. Worked the gain up gently whilst watching the input gain meter. Then gently turned up the master.

No harm done, but it sounded crap with music, as the cab was (rightly) optimised for reproducing bass guitar.

As for the fried Ampeg, you may have gotten away with it. The damage may stop it from functioning, but may not be terminal. A repair tech will give you a definitive answer. 

[BassmanPaul]

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