Potential Ampeg V4B issue

[Tommygun_ted]

So I've been feeling like my amp is sounding muddy lately, I have an ampeg v4b reissue through two ampeg av212 cabs. Comparing sound clips from about a year and a half ago, the amp sounded more bright and growly. It's come to my attention that the guitarist from the band I was in was using my head to record for his other band, and he would unplug the cab and run the head straight into the computer. The amp still seems loud, but it feels pretty lifeless compared to the way It used to sound and compared to other amps I've tried. Any ideas what may be going on?

 

[rodl2005]

Lifeless in all tube amps usually means time for new tubes.
Running that amp without a load, I thought, could've killed it, so perhaps yr lucky it's still going at all.
Hopefully someone who knows the amp will be answering soon.
Dull and lifeless, to me = power tubes being worn out. Hopefully that's all it is. 4x6L6GC tubes aren't that expensive.

 

[OneWayPunk]

That amp should NEVER be run without a speaker load attached. This can severely damage the amp.
Take it to a tech and tell him that it was run without a load and have him check it over.
The guitarist that did that needs to pay for the repairs too.

 

[beans-on-toast]

Start by replacing the preamp tubes. Check the bias on the power tubes.

 

[beans-on-toast]

Lifeless in all tube amps usually means time for new tubes.
Running that amp without a load, I thought, could've killed it, so perhaps yr lucky it's still going at all.
Hopefully someone who knows the amp will be answering soon.
Dull and lifeless, to me = power tubes being worn out. Hopefully that's all it is. 4x6L6GC tubes aren't that expensive.

Hopefully they used a dummy load.

 

[Tommygun_ted]

Any suggestions on new tubes? Not sure how much of a difference different brands make

 

[Raw N Low]

It sounds like ran the amp without your permission and ran it without a load. I'd unplug his heart from his torso and see if he's able to maintain any output.

Make sure to send him the repair bill, and his own hospital bill. I'd be very worried about the output transformers.

 

[Mr. Foxen]

Dying sound is usually down to one preamp valve failing. Which obv replacing all of them fixes. But replacing the failing one is generally cheaper.

 

[beans-on-toast]

Any suggestions on new tubes? Not sure how much of a difference different brands make

I would go to www.thetubestore.com - Your online source for audio vacuum tubes., not far in Waterloo.

See what tubes they sell and get what you can best afford. As I said earlier, you might not need power tubes. For the reissueV4B: Try the preamp tubes first. Three 12AX7's and one 12AU7. Power tubes are four 6L6GC matched.

 

[micguy]

Start by replacing the preamp tubes. Check the bias on the power tubes.

Preamp tubes are usually very long lived, and running the amp without a load wouldn't hurt them. The output tubes, though....

 

[bumperbass]

I distinctly remember a friend of mine's experience with an old Traynor 100 watt bass head. He wanted to show me what was wrong with it. So, he turned it on, let it warm up a bit, then BAM! One note through it and all 4 6L6's were toast in one big flash. No speaker load. Start with new power tubes. You probably need them anyway. Get a matched set.

 

[Mr. Foxen]

Preamp tubes are usually very long lived, and running the amp without a load wouldn't hurt them. The output tubes, though....

Not found this to be the case at all. Looking for a big old style sweet jar to fill with all the dead preamp valves I have accumulated.

 

[micguy]

Not found this to be the case at all. Looking for a big old style sweet jar to fill with all the dead preamp valves I have accumulated.

If you're going through preamp tubes, something is wrong with your amp. I've had amps with 40 year old preamp tubes. The power tubes, however, didn't last near as long.

 

[Mr. Foxen]

If you're going through preamp tubes, something is wrong with your amp. I've had amps with 40 year old preamp tubes. The power tubes, hover, didn't last near as long.

Something being wrong with them is why they are brought to me to fix. Pretty often its dying preamp valves, because they pretty commonly die. They aren't made as well as they were 40 years ago.

 

[Mr. Foxen]

Eating power valves is definitely a sign of problems though. Incorrect bias and impedance will chew them up, otherwise they are fine for years, not usually those that are pushed out of spec for distortion.

 

[elgranluis]

That amp should NEVER be run without a speaker load attached. This can severely damage the amp.
Take it to a tech and tell him that it was run without a load and have him check it over.
The guitarist that did that needs to pay for the repairs too.

Hopefully they used a dummy load.

It sounds like ran the amp without your permission and ran it without a load. I'd unplug his heart from his torso and see if he's able to maintain any output.

Make sure to send him the repair bill, and his own hospital bill. I'd be very worried about the output transformers.

LOL!!!!

Every major amp manufacturer wires the output so that you can't run the amp without a load even if it's not connected to a speaker. I think the exception would be a fender champ Or the tweed bassman that don't use a 1/4 speaker connector.


To the OP:

Save yourself the "repair bill" (definitely not broken).

If it is a 2 channel amp , try swapping the first preamp tube between channels. If your guitar is indeed "wore out" your preamp tube , you should hear the Difference. Now use that "extra Tube" for a couple of years , when it starts sounding weird , but a proper GE NOS tube that will last 15 years, not 2.

 

[beans-on-toast]

Preamp tubes are usually very long lived, and running the amp without a load wouldn't hurt them. The output tubes, though....

One hopes that they would have enough experience as to not run it without a load.

Concerning the prepues, all you really need is one known good 12AX7, substituting it one tube at a time amongst the three in the amp. Then look for an improvement. A single 12AX7 is relatively inexpensive and it's good to have a spare. Then there is one 12AU7.

After checking the power tube bias, if it turns out that they need to be replaced (ie, the bias can't be properly set), the small signal tubes can serve as spares.

This is Ampeg's power tube bias procedure. A tech can perform it.

 

[bobyoung53]

I distinctly remember a friend of mine's experience with an old Traynor 100 watt bass head. He wanted to show me what was wrong with it. So, he turned it on, let it warm up a bit, then BAM! One note through it and all 4 6L6's were toast in one big flash. No speaker load. Start with new power tubes. You probably need them anyway. Get a matched set.

Years ago the guitarist in my band plugged his guitar in his Marshall Super Lead head, no sound, kept turning the volume up, "What the heck is wring with this @@#$%$% thing?" No cab, trip to the tech. I did the same thing once with an SVT head running two heads, another trip to the tech.

 

[JimmyM]

Kill your guitarist for using it without a cab! Then check the tubes. You may get away with having burned only one or two. Honestly, though, I'd probably take it to a tech so you don't throw good money after bad chasing a problem that isn't. I've found it can get way more costly sometimes than a qualified tech who isn't in the ripoff business.

 

[DanGroove]

That amp should NEVER be run without a speaker load attached. This can severely damage the amp.
Take it to a tech and tell him that it was run without a load and have him check it over.
The guitarist that did that needs to pay for the repairs too.

+1 to this.