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Squealing like mad!

FarleyUK

Inspired
Hi all,

Just did a gig in a pub, and I had masses of really bad feedback going on. The input gate is set at -68db, amp mv at 8, gain at 6.5 (JCM800 #34).

The overall volume knob was about 2 o'clock, going into 2 DXR10'S, volume on both at 0db (so unity gain).

Anyone have any ideas on what to change to fix it? Bit of a noob question I know.... Just wondering what could be the issue.

I was also stood about 6 ft from the speakers.
 

vick1000

Inspired
Do you normally have feedback at gig volumes? Could be a bad pickup, probably the venue, or you are not setting up your patches at gig volume. You can add a second gate to the front of your chain, and just turn it off or on depending on venue geometry.
 

FarleyUK

Inspired
Cheers guys - I have also altered a few of the settings such as sag, negative feedback, speaker compression and drive etc. so I wonder if they're interacting badly at high volumes.

I set the patches up using austinbuddy's method with a LUFS meter in a DAW. The volume knob for that was fully clockwise.

I'll try resetting the amp block today at rehearsal and see if that makes a difference. Very annoying though, was pretty uncontrollable last night!
 

simeon

Axe-Master
what type of feedback? was it when you were playing, or a high pitched squeal when you're not playing? that's two different types. the second is microphonic feedback from your pickups
 

Roland

Experienced
Just did a gig in a pub, and I had masses of really bad feedback going on.
I sometimes get microphonic feedback when I’m playing in pubs. In my case it’s down to a combination of higher back line volume than I use at rehearsal, and having to stand close to the speaker because space is so limited in some pubs.
 

FarleyUK

Inspired
Post the preset.
Will do when I get a sec! :)

Is it the same preset you posted in your WDW thread?
No, this was a slightly different one - will upload later.

I sometimes get microphonic feedback when I’m playing in pubs. In my case it’s down to a combination of higher back line volume than I use at rehearsal, and having to stand close to the speaker because space is so limited in some pubs.
I have a feeling it might be this - any idea how to reduce it? Tighter gate settings for a start, I'd guess...
 

FarleyUK

Inspired
OK, here's the preset - I don't think the cabs will be included, but they're M55 ownHammer cabs.

Feel free to take a look and let me know if there's anything you see that might be the cause (or any other issues!).

Cheers all, really appreciate the help :)
 

Attachments

BBN

Fractal Fanatic
I was messing with the Brit 800 #34 last night and I felt it fed back quickly when I had too much gain (faster than other amps).
I'd suggest trying a different amp or lowering the gain.
 

Roland

Experienced
I have a feeling it might be this - any idea how to reduce it? Tighter gate settings for a start, I'd guess...
Just the traditional ones. Turn the back line volume down and / or stand off beam from the cabinet. Or you could try what I had to do on the night, which was step into the singer’s space every time I took a solo.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
The Brit 800 #34 has a ton of treble boost and will squeal with certain guitars and/or certain IRs and/or certain types of amplification. Nature of the beast. No other amp has anywhere near the amount of treble boost.

The AFD100 amp that Marshall produced years later (that was supposed to be a #34 copy) has nowhere near the amount of treble boost and has a huge snubber cap on the PI (which rolls off the treble). My gut tells me that they did this because they feared there would be too many reports of pickup squeal (or the amps would be too unstable at high gain).
 

SeeD

Power User
The Brit 800 #34 has a ton of treble boost and will squeal with certain guitars and/or certain IRs and/or certain types of amplification. Nature of the beast. No other amp has anywhere near the amount of treble boost.

The AFD100 amp that Marshall produced years later (that was supposed to be a #34 copy) has nowhere near the amount of treble boost and has a huge snubber cap on the PI (which rolls off the treble). My gut tells me that they did this because they feared there would be too many reports of pickup squeal (or the amps would be too unstable at high gain).

Would lowering the Bright Cap too 250pF, do that trick you think?
 

vkinetic

Inspired
Could be a long shot I know, but I had the exact same thing happen to me (I also use a couple of DXR10s) - we discovered that the feedback was caused by my guitar pickups, which had just been installed (Bare Knuckles) had been set too close to the strings. The feedback was really bad but everything went back to normal once the height of the pickups was backed off a bit. Maybe check that your pickup heights haven't somehow gone out of spec.
 
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