ENGL Blackmore "massive" feedback-HELP

[zupanman]

Hello, this is my first post on music-electronics forum, so sorry for any mistakes i make

So i have a ENGL Blackmore 100W hi-gain amplefier which i am using for some time now, but i was using it only at low volume in a small room for practice. But now i have the amp in a bigger place where we have a practice with band and i crank the volume up more. So the problem is that i have a lot of feedback and fuzzing with more volume. I got my self an BOSS NS-2 noise supressor and connected the whole thing with "X pattern". It helps to erase the feedback and fuzz but the sound is then weaker and messed up. I have discovered that the problem is in the FX-loop. When the balance knob for FX-loop is set to 100% the sound gets weird and it erases feedback and fuzz, but if its not on 100% its like there is no noise supressor and feedback is back but the sound is just right. So do any of you have any suggestions for what to do? Should i connect the amp-NS output-NS input-guitar? From what i have readed this connection is still feeding back but im not shure. Im not an expert for amplifiers and i dont have any other experience with other hi-gain amps so any suggestions will help a lot.

[exclamationmark]

Are you sure the 'weird tone' with the balance knob on 100% isn't just the noise suppressor doing it's thing? (or an artifact of the pedal itself). Sometimes the effects buffer tube can go bad (I've had this happen on my 6505), which in my case made my amp sound like a crappy practice amp with the loop engaged. This might explain why when the balance knob is set low, the sound is normal, because it essentially bypasses the buffer tube.

A serial effects loop (which is what you have with the balance knob on 100%) basically reduces the signal levels to effects pedal friendly levels. After it's passed through the effects, it gets boosted back up to levels enough to drive other parts of the amp. Another common problem is the return signal gets boosted way too high and pushes the effects tube buffer into clipping. Sometimes there is an option to adjust the return level. You can test if this is happening by plugging a patch cable into your effects loop, and see if you get any dramatic tone differences with the loop engaged. This also uncovers any bad driver tubes. If you find there is a problem with the effects loop itself, there are most likely ways to fix it.

Also... are you absolutely SURE you've connected the pedal the right way?

[zupanman]

Are you sure the 'weird tone' with the balance knob on 100% isn't just the noise suppressor doing it's thing? (or an artifact of the pedal itself). Sometimes the effects buffer tube can go bad (I've had this happen on my 6505), which in my case made my amp sound like a crappy practice amp with the loop engaged. This might explain why when the balance knob is set low, the sound is normal, because it essentially bypasses the buffer tube.

A serial effects loop (which is what you have with the balance knob on 100%) basically reduces the signal levels to effects pedal friendly levels. After it's passed through the effects, it gets boosted back up to levels enough to drive other parts of the amp. Another common problem is the return signal gets boosted way too high and pushes the effects tube buffer into clipping. Sometimes there is an option to adjust the return level. You can test if this is happening by plugging a patch cable into your effects loop, and see if you get any dramatic tone differences with the loop engaged. This also uncovers any bad driver tubes. If you find there is a problem with the effects loop itself, there are most likely ways to fix it.

Also... are you absolutely SURE you've connected the pedal the right way?

Yes im shure that its the FX loop knob when its at 100%. Even if there is no supressor connected to the fx loop and the know is just set to 100% the sound gets weird. The pedal is working like it has to, i have tried it at home with marshall MG 30W with everything set to the max and it does erase the feedback, but the fuzzing of the gain is still there (i assume that thats normal?) I did just put the supressor in front of the amp and in to guitar, so no X pattern and FX loop.
I will also try to connect the Blackmore that way but i dont know if it will work good and erase all the feedback because of its power.
I realy dont know how other users of amps similar to blackmore that dont have any noise supressor installed in the amp itself like Powerball II, how do they control all that feedback..
And yes im shure that the connection was right, i have the picture how it has to be connected in front of me all the time.

[exclamationmark]

Running a noise gate in front of the amp will help tame feedback and give you that staccato pick attack (if you're into that). Running it through the loop on the other hand will cut the 50/60Hz hum and 'hiss' you hear with the amp turned all the way up.

Given that the amp still shows problems with the loop at 100% and nothing running through it, it definitely sounds like the effects loop is giving you trouble. What sort of 'weird' sound are you experiencing? Some tone change is normal in most effect loops. You can try swapping the effects buffer tube with some other tube in the amp to see if that fixes your problem.

[Steve Conner]

You might also want to try simply reducing the gain. Playing a high gain amp loud is always going to cause a certain amount of "fuzzing and feedback", especially if you have a cheap guitar.

[zupanman]

The sound gets powerless and muddy, you can hear right awey that something isnt right. But if you turn off the fx loop balance know to 0, the sound gets the power back and starts to bright like it has to. Yes i know that some tone change is normal but this is like from 100W tube head to like 30W shitty combo amp.

Well i basically have all the knobs to noon, so im just switching the volume. At little less then 1/3 of the volume lvl its ok with no feedback. But we play preatty loud so thats not enough, and if i go louder the feedback comes in. I dont know what will i do if i cant controle the feedback when we have a gig.

[soundguruman]

Get rid of the effects pedals. If the amp does not sound good without effects pedals, get one that does. (there's lots of them)

[zupanman]

I dont use any effect pedals. I just need the gain of the amp for our style of playing. So what i just have is the NS2 supressor that i need for feedback which i cant control..

[soundguruman]

The gain of the amp is being pushed beyond it's usable limits. The first input stage design is usually the culprit.

[tedmich]

this is a $2k amp, it should work GREAT, try a new stock (well shielded) guitar and quality cable (ONLY) and see if its better, otherwise return to Engl for warranty work.

[Gibsonman63]

Have you tried other guitars on this amp? Sometimes a pickup will become microphonic and squeal.

[mozwell]

Maybe this sch will help
the balance on the effects loop belends between clean & wet, this insetad of a resitive mixer & a return level pot.
I guess if using a noise gate, you will need to set this to either 0% or 100%, anywhere in between will not work correctly.
I would however get rid of it out of the effects loop, adn plug you rguitar directly into it, then go from the noise gate to the input of the amp. How you set up the noise gate will affect the notes from your guitar as they decay, personally i would get rid of it. The noise gate may not be designed for the voltage signal levels on the effects loop.

As others have said, first borrow a good guitar & cable & try the amp with that, dont use the noise gate.
Also, dont be scared to turn drive pots down a bit, you may get the sound you want with less preamp drive, and with turning the master knob up more.

Does this happen on all channels, or just on the lead channel. It may be the feedback resistors & lead presence pot. 56k, 4k7, 220k, 250k pot...... or the feedback wire has come off the 8 ohm tap. If the lead presence pot was open circuit, you woudl not have the feedback & this may explain your extra squealing.

If the amp is under warranty, and you still have this problem with a good guitar, then send it back to Engl.

[zupanman]

Maybe this sch will help
the balance on the effects loop belends between clean & wet, this insetad of a resitive mixer & a return level pot.
I guess if using a noise gate, you will need to set this to either 0% or 100%, anywhere in between will not work correctly.
I would however get rid of it out of the effects loop, adn plug you rguitar directly into it, then go from the noise gate to the input of the amp. How you set up the noise gate will affect the notes from your guitar as they decay, personally i would get rid of it. The noise gate may not be designed for the voltage signal levels on the effects loop.

As others have said, first borrow a good guitar & cable & try the amp with that, dont use the noise gate.
Also, dont be scared to turn drive pots down a bit, you may get the sound you want with less preamp drive, and with turning the master knob up more.

Does this happen on all channels, or just on the lead channel. It may be the feedback resistors & lead presence pot. 56k, 4k7, 220k, 250k pot...... or the feedback wire has come off the 8 ohm tap. If the lead presence pot was open circuit, you woudl not have the feedback & this may explain your extra squealing.

If the amp is under warranty, and you still have this problem with a good guitar, then send it back to Engl.

The guitar is fine, we switched guitars at practice and its the same thing and we use good guitars and quality cables.
The problam is that i didnt bought a new head, so im the second user and dont have warranty.
I have to try how it reacts if i put the supressor just before the amp, so from amp to NS2 output and from there to guitar like you said that i should do.
So in my case on this amp, the preamp is the lead volume and lead prestance if im right?
I dont remember for other channels, i think i never tried it because i only use the 4th lead channel for our type of music that needs only a lot of distortion.
As far is i remember i get most of the feedback when i turn up the lead prestance so could this be the problem that you just described? I will have to experiment some more next week when i come there.
Or if its that wire thing (i realy dont know much about inside equipment), are there any other things that i can test to make shure if theres a problem about that? and if i take the head to tech can they fix it, beacuse i dont have a warranty like a said.

[exclamationmark]

The noise gate works fine in front of the amp to stop feedback, but the amp will still buzz. Not a huge problem if you're playing in a band though, because it's inaudible unless you all stop playing (tbh I never had a problem with feedback unless we stopped playing - but I always roll my volume pot back whenever we stop playing). There are also certain spots around the room that will feedback more than others (Santana had spots marked around the stage with large 'X's).

[Gibsonman63]

Have you tried different preamp tubes? A microphonic tube will take off and give you fits. I have a couple of semi-microphonic NOS Siemens power tubes that sound really good in one of my amps, but I have to put my amp head on a keyboard stand instead of on the speaker cabinet to use them. You may try isolating the head from you cabinet to see if it improves.