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Engl Powerball II - Clean channel not so clean


Zanna83

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Dear all,

 

I'm having some troubles with my Powerball II, i cannot get the channel 1 as clean as I expect. Even with very low gain i always hear a crunchy sound... something buzzing. I tried to set the EQs in many different way but no results. The problem occurs with all my guitars.

 

Any idea ?

 

My gear:

Engl Powerball II

Harley Benton G212V speaker (2 x 12" Celestion Vintage 30)

Ibanez RG2550Z (Di Marzio Air Norton (F) - Di Marzio The Velvet (M) - Di Marzio The Tone Zone (B))

Godin XTSA (Di Marzio D-ActivatorX (B) - Di Marzio Liquifire (F))

Schecter KM-7 . (S.Duncan Nazgul (F) - S.Duncan Sentient (B))

 

I'm going mad!!

 

 

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You did buy a heavy metal head and it looks to me like all your guitars have hot wound pickup with high gain outputs.

Clean channels are usually gain staged for standard output pickups, PAF on the high output side and vintage fender on the low output end.

 

Every pickup you got has double or more the normal output, then you have an amp that's designed to make standard pickups as driven as those hot wound pickups. How do you spell Overkill? Its no wonder the clean channel doesn't sound clean.

 

Seriously though. I suspect many who buy those heads are metal players who use overwound pickups and the clean channel should be able to do the job so we'll consider some possibilities.

 

First might be a warped voice coil in a speaker or a speaker whose frame isn't mounted level. If the frame of the speaker is twisted slightly because its not tightened down evenly, it can torque the speaker diaphragm and move the voice coil out of alignment making it rub within the extremely narrow channel. This can cause that buzzing sound you mentioned. Its only noticed on the clean channel because the drive masks it.

 

What you need to do is check the speaker manually. open the cab and move the cones by hand and see if you hear any rubbing. If you do you need to tighten and loosen the mounting screws to get even pressure holding the speaker down against the frame until the noise disappears. It may be a screw has loosened from the vibration making the frame torque uneven. Don't over tighten or you'll bend the frame.

 

Its also possible the voice coil warped. A pair are rated for 120W but its still possible because heads are rated for clean watts and a 100W head can put out higher wattages when pushed into saturation. Rule of thumb is usually to have at least 50~100% additional wattage headroom on the speakers, especially on a monster head like the one you have. If the speaker rubs and re-torqueing the frame doesn't fix it then the speaker is likely cooked or defective.

 

Next, your issue may be a bad preamp tube used for the clean channel. Manufacturers don't use the best tubes made and it may have crapped out early, especially when pushing it with high output pickups. You can probably swap the preamp tubes to see if you hear a change. This amp may have 3 or more 12AX7 tubes, Mark them as 1, 2, 3 and 4 then put 4 in the first position, move 1 to 2, 2 to 3, 3 to 4 and rotate them like you're moving from the front desk in the class to the back of the class one desk at a time and the guy at the back of the class moves to the front.

 

If the clean channel clears up or changes then you know its a defective tube and you'll likely want to change the set for something more durable.

If the inverter is a 12AT7 then you'll need to try that one with a like for like.

 

The problem could also be the power tubes. Tube bias can fluctuate, especially when a head is new and the tube get some hours on them. you may need to have them re-biased to not only have the correct gain levels but so they are balanced.

 

Next your problem may be channel bleed. If you are using a non factory channel switcher you may be getting some bleed from say a crunch channel into the clean channel as a ghost image. This can be a switch, the cable itself, even left over solder rosin on a circuit board that's conducting a small amount of signal from one of the dirt channels over to the clean channel. Some amps also use active switching through transistors via the pedal and when one overheats it may not switch cleanly and allow channel bleed over. If you switch channels without a pedal I'd think this is a likely scenario having seen it many times in my repair days. It can also be a switch that was overheated when soldered into place or any number of similar issues.

 

Channel bleed can be simple or complex. You'd need an experienced tech to circuit trace the amp and find the fault in most cases unless you have some additional info that expends the symptoms.

 

Unfortunately that's about it. I'd check the speakers, Try a guitar that has low output pickups, try swapping or replacing the preamp tubes, Oh and make sure you're using a heavy duty speaker cord. Never, Ever use a shielded guitar cord on a cab. You'll melt them from the inside out. Only use heavy gauged dual wire speaker cable, shorter the better.

 

Other then that you'll need to have a tech look at it. Tube amps are high maintenance. You better find a friendly tech who knows tube technology and treat him right or your life will become most difficult as that amp ages. Allot of these new tube amps have no track record and you simply don't how durable that can wind up being, especially ones that are more complex like yours which has multiple channels. The more complex the greater chance of failures and the better the tech needs to be to find the faults which means you pay top dollar to keep it in shape.

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Thank you man for your extremely exhaustive answer!

 

Regarding the pickups of my guitars, that was also my thought; I think there may be some clipping in the preamp stage. Since the distortion is stronger on the lower frequency, maybe I can try to add a compressor in the chain or make some sort of soft "high-pass" to equalize the lower frequencies.

 

Regarding the problem of the frame in the speaker I will check, that's a possible reason!

 

I don't think the 120W limitation is a problem, usually I play at home with lower volumes. Far away from the 100W (far away also from the 30W I think).

 

Then... I will try to switch the pre-amp valves for sure! Regarding power valves and the bias, I leave this option for last because I don't feel comfortable putting my hands inside a valve ampifier... a technician is required!

 

Actually i'm switching channels from the front panel of the head, no switcher. When i will reorganize my pedalboard, I will probably use a midi footswitch with an ENGL Z11 switcher. But for now... it cannot be the problem!

 

The speaker cable is ok, i'm not worried about it!

 

Thank you again for your help!

 

 

 

 

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You did buy a heavy metal head and it looks to me like all your guitars have hot wound pickup with high gain outputs.

Clean channels are usually gain staged for standard output pickups, PAF on the high output side and vintage fender on the low output end.

 

Every pickup you got has double or more the normal output, then you have an amp that's designed to make standard pickups as driven as those hot wound pickups. How do you spell Overkill? Its no wonder the clean channel doesn't sound clean.

 

Seriously though. I suspect many who buy those heads are metal players who use overwound pickups and the clean channel should be able to do the job so we'll consider some possibilities.

 

First might be a warped voice coil in a speaker or a speaker whose frame isn't mounted level. If the frame of the speaker is twisted slightly because its not tightened down evenly, it can torque the speaker diaphragm and move the voice coil out of alignment making it rub within the extremely narrow channel. This can cause that buzzing sound you mentioned. Its only noticed on the clean channel because the drive masks it.

 

What you need to do is check the speaker manually. open the cab and move the cones by hand and see if you hear any rubbing. If you do you need to tighten and loosen the mounting screws to get even pressure holding the speaker down against the frame until the noise disappears. It may be a screw has loosened from the vibration making the frame torque uneven. Don't over tighten or you'll bend the frame.

 

Its also possible the voice coil warped. A pair are rated for 120W but its still possible because heads are rated for clean watts and a 100W head can put out higher wattages when pushed into saturation. Rule of thumb is usually to have at least 50~100% additional wattage headroom on the speakers, especially on a monster head like the one you have. If the speaker rubs and re-torqueing the frame doesn't fix it then the speaker is likely cooked or defective.

 

Next, your issue may be a bad preamp tube used for the clean channel. Manufacturers don't use the best tubes made and it may have crapped out early, especially when pushing it with high output pickups. You can probably swap the preamp tubes to see if you hear a change. This amp may have 3 or more 12AX7 tubes, Mark them as 1, 2, 3 and 4 then put 4 in the first position, move 1 to 2, 2 to 3, 3 to 4 and rotate them like you're moving from the front desk in the class to the back of the class one desk at a time and the guy at the back of the class moves to the front.

 

If the clean channel clears up or changes then you know its a defective tube and you'll likely want to change the set for something more durable.

If the inverter is a 12AT7 then you'll need to try that one with a like for like.

 

The problem could also be the power tubes. Tube bias can fluctuate, especially when a head is new and the tube get some hours on them. you may need to have them re-biased to not only have the correct gain levels but so they are balanced.

 

Next your problem may be channel bleed. If you are using a non factory channel switcher you may be getting some bleed from say a crunch channel into the clean channel as a ghost image. This can be a switch, the cable itself, even left over solder rosin on a circuit board that's conducting a small amount of signal from one of the dirt channels over to the clean channel. Some amps also use active switching through transistors via the pedal and when one overheats it may not switch cleanly and allow channel bleed over. If you switch channels without a pedal I'd think this is a likely scenario having seen it many times in my repair days. It can also be a switch that was overheated when soldered into place or any number of similar issues.

 

Channel bleed can be simple or complex. You'd need an experienced tech to circuit trace the amp and find the fault in most cases unless you have some additional info that expends the symptoms.

 

Unfortunately that's about it. I'd check the speakers, Try a guitar that has low output pickups, try swapping or replacing the preamp tubes, Oh and make sure you're using a heavy duty speaker cord. Never, Ever use a shielded guitar cord on a cab. You'll melt them from the inside out. Only use heavy gauged dual wire speaker cable, shorter the better.

 

Other then that you'll need to have a tech look at it. Tube amps are high maintenance. You better find a friendly tech who knows tube technology and treat him right or your life will become most difficult as that amp ages. Allot of these new tube amps have no track record and you simply don't how durable that can wind up being, especially ones that are more complex like yours which has multiple channels. The more complex the greater chance of failures and the better the tech needs to be to find the faults which means you pay top dollar to keep it in shape.

 

Best response ever. I'm always confused by people who play a {censored}tily modded LTD with Blackouts or Invaders and want to know why the clean channel on their brand new Randall Satan amp sucks. Lol.

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