Ampeg v4b reissue problems.

[beans-on-toast]

@beans-on-toast would it be ok to "daisy-chain" the cabs plugging into the 4 ohm speaker out?

It is best that the total daisy chained cabinet impedance matches whatever tap is used.

The 4 ohm jacks on the back of the chassis are internally connected in parallel. Plugging in two 8 ohm cabinets, one into each jack is the same as daisy chaining two 8 ohm cabsand using one jack.

In the case of a 4 ohm and an 8 ohm cab, daisy chained, the total impedance would be 2.7 ohms. This is a mismatch for this amp and Ampeg does not recommend doing this.






People do run their amps with mismatches and would argue as to which is best to use, the 2 ohm tap or the 4 ohm tap. I wouldn't recommend either. But if it were done, using the 4 ohm tap would be best. This would be at the expense of running the tubes down faster and more heat in the output transformer which could damage it long term. What you can get away with also depends on how hard the amp is driven. There are always tradeoffs and risks when you want to go against the manufacture's recommendations.

Chances are, the speaker cabs will not perform the same which would result in one being louder. It depends on the speakers and cab design. It would have to be tried to see.

 

[SpottedBass]

I love my V4b 2013 reissue, but I am tired of replacing power tubes every 18 months. I always buy a matched set of 6L6GC's and replace all 4 at the same time. Am I doing something wrong by not having a tech rebias? I was under the impression that I do not need to do that if I replace all 4 with a matched set. Maybe this is normal for an all tube amp? Appreciate any advice...

 

[JimmyM]

I love my V4b 2013 reissue, but I am tired of replacing power tubes every 18 months. I always buy a matched set of 6L6GC's and replace all 4 at the same time. Am I doing something wrong by not having a tech rebias? I was under the impression that I do not need to do that if I replace all 4 with a matched set. Maybe this is normal for an all tube amp? Appreciate any advice...

Every 18 months? Are you cranking it a bit?

As for rebiasing, unless your new tubes are matches of your old tubes, it should be done every time you change power tubes, yes, and that can affect the life of the tubes if it's biased too hot. But if you have a multimeter and can open it up without electrocuting yourself, here's how to do it:

 

[coreyfyfe]

I love my V4b 2013 reissue, but I am tired of replacing power tubes every 18 months. I always buy a matched set of 6L6GC's and replace all 4 at the same time. Am I doing something wrong by not having a tech rebias? I was under the impression that I do not need to do that if I replace all 4 with a matched set. Maybe this is normal for an all tube amp? Appreciate any advice...

How long power tubes will last is always variable, depends on how they're biased, the frequency and duration of usage of the amp, and sometimes just random luck. I had a power tube with fairly light use short plate to heater recently, took the hum balance pot and fuse with it and made for a nice smoke show. It happens. But yeah, every 18 months sounds fairly short unless you've got them biased hot and use the amp daily.

As Jimmy said, you should check the bias every time you retube.

 

[SpottedBass]

Thanks Jimmy! This sounds pretty easy and I'm not afraid to probe around with a meter. I've never biased the amp ever - I just swap out all 4 power tubes when I start getting 'that hissy-poppy thing'. I'd take it to a shop, but with all horror stories about long wait times and incompetent work here in Southern California I'd rather try it myself. Thanks for posting the step-by-step.

I do tend to keep the master at 100% and use the drive to regulate volume, but I don't get that loud overall. I also usually keep the master at 100% when powering up. Someone told me I should always power up with master at zero initially. Not sure if thats a factor.

 

[Bass 45]

Thanks Jimmy! This sounds pretty easy and I'm not afraid to probe around with a meter. I've never biased the amp ever - I just swap out all 4 power tubes when I start getting 'that hissy-poppy thing'. I'd take it to a shop, but with all horror stories about long wait times and incompetent work here in Southern California I'd rather try it myself. Thanks for posting the step-by-step.

I do tend to keep the master at 100% and use the drive to regulate volume, but I don't get that loud overall. I also usually keep the master at 100% when powering up. Someone told me I should always power up with master at zero initially. Not sure if thats a factor.

Hopefully the bias will help. My V4B RI is still going strong on the original tubes - and it is one of the early ones produced. I did have to readjust the bias at one point using the instructions above - not a difficult process IIRC.

 

[beans-on-toast]

I love my V4b 2013 reissue, but I am tired of replacing power tubes every 18 months. I always buy a matched set of 6L6GC's and replace all 4 at the same time. Am I doing something wrong by not having a tech rebias? I was under the impression that I do not need to do that if I replace all 4 with a matched set. Maybe this is normal for an all tube amp? Appreciate any advice...

I guess the question is, Why are concluding that the power tubes need to be changed so often? In general, if you can not set the bias as per the proceedure, then it is time to change the power tubes.

Here is a guide that helps you determine when to change tubes: Tubes | TalkBass.com

 

[SpottedBass]

Very helpful guide to Tubes. In my case, it's not a gradual "something sounds off" thing. It's a steady hiss and pop sound, almost like scratchy pot, but happens with nothing plugged in and the dials in any position. First time it happened, it was the next day after moving the amp from a room that was about 75 degrees to a back seat of a car that was about -7. I let the amp cool, but not long enough. Most recently, the amp has been sitting in the same room for about 8 months with no significant temp change. Each time, a new set of power tubes fixes it.

 

[JimmyM]

Very helpful guide to Tubes. In my case, it's not a gradual "something sounds off" thing. It's a steady hiss and pop sound, almost like scratchy pot, but happens with nothing plugged in and the dials in any position. First time it happened, it was the next day after moving the amp from a room that was about 75 degrees to a back seat of a car that was about -7. I let the amp cool, but not long enough. Most recently, the amp has been sitting in the same room for about 8 months with no significant temp change. Each time, a new set of power tubes fixes it.

What's probably happening is one tube gone bad. Tube amps rarely have all power tubes go out at the same time. Has to be a catastrophic event for that to happen. This is why when I buy power tubes again, I'm going to get double the amount I need to make sure I have matches when only one goes bad

But sometimes you may think it's a tube and it's something else, and coincidentally it goes away with new tubes. Have you tried other fixes for it, like swapping power tubes around or pulling them out and reseating them when that happens?

 

[rodl2005]

If it were me. .. I'd be making damn sure it weren't sumthin else before I went changing power tubes! I've had my V4B for near 4 yrs and ain't had to swap ANY tube -pre nor power.
ANY unwanted noise. ..pops...hisses. ...static. ..whines...whistles.... I ALWAYS check pre amp tubes as a 1st point of call. And 99% of the times. ... it's either been a pre amp tube problem or a power problem in the venue.
Lucky? Dunno. ..but I've been playing all tube amps since the mid 70s and I could count on one hand the amount of times I've replaced a whole set of power tubes.

 

[beans-on-toast]

Very helpful guide to Tubes. In my case, it's not a gradual "something sounds off" thing. It's a steady hiss and pop sound, almost like scratchy pot, but happens with nothing plugged in and the dials in any position. First time it happened, it was the next day after moving the amp from a room that was about 75 degrees to a back seat of a car that was about -7. I let the amp cool, but not long enough. Most recently, the amp has been sitting in the same room for about 8 months with no significant temp change. Each time, a new set of power tubes fixes it.

What you are describing is more commonly associated with pre-amp tubes. But there are other possibilities that a tech can look into.

As was mentioned, you can burn out power tubes if the bias is set too hot. I would check this first.

All amps require some maintenance. It wouldn't hurt to have the tube socket contacts cleaned with deoxit when maintenanc is performed. Sometimes cycling a tube in and out of a socket can clean it enough to make a difference.

If a tube socket contact is loose, this can cause a scratchy sound. The solution is to retension the socket. A tech would removed the tube and carefully pinch the contact closed. Not all tube pins from one brand to another are the same size. A large pin can stretch out the contact, if you replace the tube with one with smaller sized pins, the contact can be loose causing the scratch sound. It is a simple fix. One test for a loose socket is how easily a tube pulls out out of the socket. You should feel some friction, if it slips in and out too easily, the socket contacts are loose.

Another possibility for the symptoms that you described is a bad solder joint. This is something a tech can look for.

I would have a good tech check out the amp. Describe all your symptoms. What you are describing is not normal.

 

[SpottedBass]

I would have a good tech check out the amp. Describe all your symptoms. What you are describing is not normal.

Well, its never been gone over since day 1 so I think you are right - its time to go to the amp-doctor for a check-up. It sounds like this is not normal. I like the amp enough to work through the issue. All my prior amps have been hybrid or solid state, so I wasn't sure if this was 'normal' for an all tube amp. Any good amp techs you might reccommend either in Southern California or the Dallas-Fort Worth area? Thanks everyone!

 

[beans-on-toast]

Any good amp techs you might reccommend either in Southern California or the Dallas-Fort Worth area? Thanks everyone!

There is a link in the Amp FAQ for amp techs included below. Otherwise, it might be a good idea to start a new thread asking for recommendations in the two areas. That way you'd get a current list.

Good Amp Techs - TB Members Recommendations for

 

[13ehg]

Hello everyone at Talkbass,

I found this topic, figured it's the appropriate place to ask a question.
I own an Ampeg V4B reissue from China. Purchased it as new in July 2017, Poland, Europe.
The amp is connected right now to a Gallien Krueger 8Ohm Cabinet.
It sounds fine, all of the controls and knobs work. When the amp is in standby mode the red light is on, when I switch it to On mode it goes green, however almost as soon as I play the bass it flickers between red and green (mostly red). Sound is still ok. After a few minutes of normal playing it stays mostly green, but slightly flickers toward red.
I'm not really a 'tech' guy, but maybe you guys might have any ideas if that might be a major issue?

Kind regards

 

[Bass 45]

It is doing what it should. You are fine.

The bias LEDS require that the amp is in playing mode, standby off, and that there is no input to the amp. Unplug your bass. When you plug in and play, ignore what the bias LED is doing.

When you are adjusting the bias, the amp has to be warmed up for at least 20 minutes in playing mode. This ensures that all the components such as the resistors are warmed up and are not drifting.

David, I think the previous poster is reffering to the power light on the front panel. My uneducated geuss is a poor connection at the light itself.

 

[beans-on-toast]

David, I think the previous poster is reffering to the power light on the front panel. My uneducated geuss is a poor connection at the light itself.

Thanks Rich! Boy, was I ever confused, there are no bias LED's on the V4B. I was thinking of another amp. I deleted my post.


_______________


The power light is green with power on, standby off (playing mode); red with power on, standby on (amp in standby mode). The power/standby bicolor LED is controlled by a two transistor circuit which is powered by a +15VDC power supply. When the standby switch is closed, the high voltage is turned on. The transistors switch the LED color from red to green when the hight voltage comes on.

Since the amp sounds fine when the LED is flickering, that tells me that the high voltage power is fine. A tech would verify this with test equipment. There is a cable that runs from a connector at the transistor circuit to the LED. I suspect that the connection is loose. I would open the amp and inspect this cable. Check the connectors and ensure that they are seated properly. At the same time check that all the other connectors are fully seated.

cc: @13ehg

 

[13ehg]

Thanks Rich! Boy, was I ever confused, there are no bias LED's on the V4B. I was thinking of another amp. I deleted my post.


_______________


The power light is green with power on, standby off (playing mode); red with power on, standby on (amp in standby mode). The power/standby bicolor LED is controlled by a two transistor circuit which is powered by a +15VDC power supply. When the standby switch is closed, the high voltage is turned on. The transistors switch the LED color from red to green when the hight voltage comes on.

Since the amp sounds fine when the LED is flickering, that tells me that the high voltage power is fine. A tech would verify this with test equipment. There is a cable that runs from a connector at the transistor circuit to the LED. I suspect that the connection is loose. I would open the amp and inspect this cable. Check the connectors and ensure that they are seated properly. At the same time check that all the other connectors are fully seated.

cc: @13ehg

Hey thanks for your opinion, I'll try to delicately investigate the cable connection.

 

[AmericanFenderJazzMan]

so can you run an ampeg V4 reissue through a 610 cab? how would that effect sounds?

 

[Bass 45]

so can you run an ampeg V4 reissue through a 610 cab? how would that effect sounds?

The V4 reissue is designed to run with a 2, 4, or 8 ohm load - so you can use it with any cabinet (or combination of cabs) that are rated at 2,4, or 8 ohms.

The V4 sounds great through any good quality cab in my experience.

 

[AmericanFenderJazzMan]

The V4 reissue is designed to run with a 2, 4, or 8 ohm load - so you can use it with any cabinet (or combination of cabs) that are rated at 2,4, or 8 ohms.

The V4 sounds great through any good quality cab in my experience.

hmm cool.i wonder what it would sound like through my ashdown 610 cab...no doubt good I assume