??Do YOU Own A Rectifier Amp That POPS??

[barneyc4]

I am the previous owner of an F-50 and the current owner of a Roadster. Those are only tube amps I have ever owned. Unfortunately, I have experienced the annoying channel switching pop on both of them.

I am very curious to know how you guys are dealing with your Rectifiers that pop? I have tried the "let the amp warm up and switch through the channels on stand by" trick and it did not work. How are you dealing with it on stage? How do you get over it?

 

[ibanez4life SZ!]

Mine has never popped....it's an '06 model.

 

[Russ]

No pops on my '94 :wink:

 

[Storm]

Yeah, my Roadster pops but I just put up with it unfortunately.

Ciao ...

 

[Russ]

FWIW it was discussed on here before. I think the work around is you let your amp warm up then switch through the channels a couple times. It was static electricity buildup in the switching circuit that is developed when you power up your amp. At least that was the fix for the RoadKing.

 

[Storm]

Yep, read all the threads and bought the t-shirt. Nothing works so if you can't beat it, just stfu!! :lol:

Ciao ...

 

[axelfatu]

RK 2 Head here and it pops - about to sell it

 

[Boogiebabies]

DR 3 Channel - Popped
RK1 - No pop
RK II - Popped
RK II v.2 - Popped
RK II v.2 #2 - No pop

Up to 2000 Mesa used LDR's for switching instead of .05 cent J175 transistors. So for for saving $ 5.95 each for the few dozen switching functions, we get the pop. Some switching transistors are noisy and some are not. I doubt Mesa would test them before using them with the amount of amps they are selling. It would be like gain matching every tube to 100 per triode on every amp they sell. The saddest part of this is these amps that pop are louder than the threshold for the muting circuit. In design and theory they are not supposed to allow a pop. It's part of the Black Magic.

 

[barneyc4]

So whats going on with those people that are buying USED amps that pop? Do they like the pop or what?

 

[junior]

my dual rec 3ch pops, when switching to the 2nd channel the pop is louder
but at higher volumes i think the pop stops
i don't know for sure, but i don't hear any pops when i'm playing live

 

[Boogiebabies]

It's just something in the design. These little quirks are annoying, but all the switching and matrix designs on these amps rely on J175 transistors and relays. I remember talking to Mesa CS about the RK II pop. The guy said, " Well, remeber the IIB? It popped, but it was a great amp".

 

[Platypus]

My 3CH DR popped for the first few months I had it and then stopped forever before I sold it.

Made using delay VERY annoying.

 

[jvk]

The reason they give to some people for the popping in their 3ch Recto / RK / Roadster is ridiculous... static build-up?? They're full of crap... here's why...

When the amp's channel select switch is on footswitch mode and the amp is powered on, notice how none of the channel LEDs on the amp/footswitch light up until one of the channels is selected. That means that none of the channel selection relays are turn on. Bearing that in mind, the muting circuit only comes into action when the relays are turning off. So the first time you turn the amp on none of the channels are selected so the relays associated with them aren't on to begin with, and so switching to another channel doesn't turn any relays off and so doesn't trigger the muting circuit. Simply put, one of the channels needs to be selected first before the relay muting kicks in. It's got NOTHING to do with static buildup. They could've easily rectified this by adding a circuit that selects one of the channels when you first power it up.

Consistent popping whilst switching is something else. There are lots of other amps that are packed with relays; Peavey have been stuffing their amps with relays for years, the 5150 is dead quiet. Diezels, Marshalls, Bogner and VHTs all use relays, yet no pops.

Here's how the switching sequence works: when the channel selection is made, some relays are turned off and others on. The relays turning on remakes the circuit continuity almost instantaneously and generates a sudden increase in the signal level, which when amplified is heard as a pop. In the relays which turn off, the collapsing voltage across the coil generates a voltage spike, which triggers an RC timing circuit. The RC circuit turns on muting transistors which drive the signal to ground with J175 FETs, and so suppressing the sudden spike in the audio signal.

Ideally going 'switch+pop+mute' to 'unmute' is supposed to take 10-30ms, depending on the switching speed of the relays, with 30ms being the norm with most manufacturers. It could be that this time period has been set too short. Or like Boogiebabiez said, the FETs are misbehaving. I think it's most likely the former.

Solutions
Increase the RC time constant. The RK/Roadster and Recto have R=100k and C=.1u, giving a mute of 10ms. Increasing this to ~20ms more might work, with setting C=.22u. Downside is that the muted gap in the signal will become more obvious.

Replace FETs with better quality ones. There's at least a dozen of them in the RK.

Or live with it?

 

[Mr_You]

My `06 Roadster only pops after powering the amp up and the first channel change or two. Cycling through the channels (not in standby) and the "pop" is gone.

 

[jvk]

Another thing I noticed. On the Recto, changing the modes does turn relays on/off, but strangely they're not connected so that they could trigger the mute circuit. So changing the modes will always produce a pop.

 

[Storm]

Hmmm, interesting. So what capacitors do we change, where's their location on the PCB?

Ciao ...

 

[jvk]

Take detailed, high res shots of your circuit boards and i'll figure it out. I seriously think my mods could work. We can experiment with the value of that cap.

 

[Boogiebabies]

The reason they give to some people for the popping in their 3ch Recto / RK / Roadster is ridiculous... static build-up?? They're full of crap... here's why...

When the amp's channel select switch is on footswitch mode and the amp is powered on, notice how none of the channel LEDs on the amp/footswitch light up until one of the channels is selected. That means that none of the channel selection relays are turn on. Bearing that in mind, the muting circuit only comes into action when the relays are turning off. So the first time you turn the amp on none of the channels are selected so the relays associated with them aren't on to begin with, and so switching to another channel doesn't turn any relays off and so doesn't trigger the muting circuit. Simply put, one of the channels needs to be selected first before the relay muting kicks in. It's got NOTHING to do with static buildup. They could've easily rectified this by adding a circuit that selects one of the channels when you first power it up.

Consistent popping whilst switching is something else. There are lots of other amps that are packed with relays; Peavey have been stuffing their amps with relays for years, the 5150 is dead quiet. Diezels, Marshalls, Bogner and VHTs all use relays, yet no pops.

Here's how the switching sequence works: when the channel selection is made, some relays are turned off and others on. The relays turning on remakes the circuit continuity almost instantaneously and generates a sudden increase in the signal level, which when amplified is heard as a pop. In the relays which turn off, the collapsing voltage across the coil generates a voltage spike, which triggers an RC timing circuit. The RC circuit turns on muting transistors which drive the signal to ground with J175 FETs, and so suppressing the sudden spike in the audio signal.

Ideally going 'switch+pop+mute' to 'unmute' is supposed to take 10-30ms, depending on the switching speed of the relays, with 30ms being the norm with most manufacturers. It could be that this time period has been set too short. Or like Boogiebabiez said, the FETs are misbehaving. I think it's most likely the former.

Solutions
Increase the RC time constant. The RK/Roadster and Recto have R=100k and C=.1u, giving a mute of 10ms. Increasing this to ~20ms more might work, with setting C=.22u. Downside is that the muted gap in the signal will become more obvious.

Replace FETs with better quality ones. There's at least a dozen of them in the RK.

Or live with it?

Sadly you did not mention that this would be all for naught in the event of an EMP.

 

[jvk]

I do think that Boogies will outlive humans incase of a nuclear fallout and the ensuing electromagnetic pulse (EMP). Mutant humans and 10ft lizards can then learn to rawk all over again.

 

[73h Nils]

My Roadster's channel 3 and Tuner Mute switching pops only the first time I use them and then it's gone for good.