Turntable Feedback

[otronics 0]

I was using my Stanton T.50 deck for the first time at the Weekend.

 

4 speaker set-up and placed the deck on the table, not far away from the speakers.

 

Noticed some low-end feedback when playing certain records at low volume and when turned up it was dreadful (this was at the sound check stage).

 

Moved it on top of my flightcases and was better but had to keep on lower volumes than CDs and cut a lot of bass so did not sound good.

 

I am using a compressor but this only adds a slight amount of AGC but obviously does not help the situation.

 

Speakers and table not touching. There are rubber feet on the deck.

 

How do I prevent this feedback?

[HalfPint 0]

I was using my Stanton T.50 deck for the first time at the Weekend.

 

4 speaker set-up and placed the deck on the table, not far away from the speakers.

 

Noticed some low-end feedback when playing certain records at low volume and when turned up it was dreadful (this was at the sound check stage).

 

Moved it on top of my flightcases and was better but had to keep on lower volumes than CDs and cut a lot of bass so did not sound good.

 

I am using a compressor but this only adds a slight amount of AGC but obviously does not help the situation.

 

Speakers and table not touching. There are rubber feet on the deck.

 

How do I prevent this feedback?

 

 

Obviously the first thing is to try and eliminate the vibration back to the turntable. However easier said than done.

 

Move Speakers ( BASS) as far away for Decks as possible and stage. Was the Stage hollow and the bass coming through the stage?

 

You can try foam and other suspension items, its a question or trial and error.

 

Sometimes going the other way can help. IE very heavy item being used as a base for decks. The mass of the item will stop vibration. (YOU COULD EVEN USE BRICKS ~ the big Block types they use for inner walls)

 

A sub sonic filter will also help ~ cut off frequencies below 30 / 45 Hz.

 

 

--------

 

 

Finally, play it at a lower volume !

 

[RobbieD 0]

Halfpint is giving some excellent advice here.

 

Isolation and mass are the keys.

 

Many clubs used to have their decks stood on paving slabs. And I once did this myself after playing at a new club. They didn't have feedback as such, just a woolly bass boom instead of a nice thud - bass drums sounded more like some tapping the side of the deck. The next time I was their I took in two paving slabs and put them under the decks, and suddenly the bass sounded great - they were even able to turn the subs up as the nasty boom that affected the bar area was gone!

 

I have also seen decks on foam and once suspended from the ceiling on chains!

 

At one of the DMC mix championships (can't remember which one) they had terrible problems with feedback due to the wooden stage. They ended up bringing in a couple of filled chest freezers with a sheet over them to replace the previous deck stands and solve the problem.

[superstardeejay 0]

Now we're getting to the nitty-gritty. This issue is why clubs install Technics. They are about the only decks to really withstand feedback and they can even still hum a bit even on concrete mounts with a big PA! I dont suppose the Stantons will really stand a chance.

 

 

 

 

[Andy Westcott 0]

Any idea roughly what frequency it is feeding back at?

 

Feedback when using vinyl can never be eliminated - all you can do is hope to reduce it to non-problematic levels by taking note of the suggestions posted earlier. Quite simply, even if you succeeded in 100% isolation of the plinth, the sound from the speakers would still vibrate the record surface, and when total gain exceeds unity, you'll howl away anyhow!

 

I used to have this problem, but oddly enough it wasn't at sub-bass frequencies, more in the 60 - 80Hz region; Not entirely sure why that was, but as this particular issue occurred at just one venue, I put it down to standing wave effects. With this in mind, you may just find that setting up in a different location (if possible) may improve matters.

 

One of the great benefits of CDs and HDD sources.

[NiM 0]

Used to get this alot when I used to use the F1s on the under 18s night..

 

 

 

Freefloats solved my problems.. www.freefloat.net if I remember rightly..

 

 

[norty303 0]

If you can get hold of a parametric EQ then use a very narrow Q notch filter, and sweep it around the 40-10hz area until you find the problem frequency. With Technics, a notch at 80hz usually sorts it out.

 

There are a number of cheap solutions you can make to isolate the decks. Easiest is to get a length of waste pipe and cut short ring sections from it. Then get those big heavy rubber bands and wrap them so they run all ways over the opening. Put one under each foot of the deck and you're away. You can put a deck directly on a 2000w sub with these and not suffer any feedback (tested!)

 

If you need to firm it up, add more bands, or tighten the ones on it further.

[otronics 0]

It was around (likely below) 50Hz. Can't be exact without looking at it all.

 

I see there are lots of products that help to cure this issue.

 

Ref/ parametric EQ - would be nice but no point as would not used very often at all.

 

Thanks for the advice all, I may get everything out and test soon.

 

More details I meant to add before this forum was upgraded (!):

 

Wooden floor but good acoustics in the room.

 

One table had had it and was bowing so used flightcases to prop it up. Worked a treat but did isolation no good whatsoever.

[norty303 0]

Reference the 'wouldn't get used much' comment....

 

Do you not use a graphic EQ as a matter of course when you take your system out? (this question to everyone really not just you)

 

There are very few systems that I've seen/heard that don't benefit some EQ'ing regardless of the situation (bar stuff that has dedicated system controllers like Nexo, etc)

 

If you're going to use an EQ on your system then a parametric is generally better, as it can give much better curves than a regular EQ, and once its been adjusted for the gig, it normally doesn't need fiddling with. Of course you can use a regular EQ for notching but they tend to have a fixed Q on the cheaper end ones and take out more than might be desirable, especially if it's not 29+ bands.

[otronics 0]

If I were to get a Parametric EQ it would not get used much....standard Graphic EQ is all I require.

 

I use that every gig and it makes a huge difference.

 

Every disco and sound rig should use one without question.

[Welsh Audio Man 21 0]

 

Every disco rig should use one without question.

 

why?

 

i can understand sound rig, but disco rig?

[wizard 0]

why?

 

i can understand sound rig, but disco rig?

 

Agree 100% the EQ is put on when the song was recorded ...why add to it.

 

 

 

[Andy Westcott 0]

Ah, but PA speakers, no matter how good or expensive, are not Hi-Fi.

 

There will inevitably some peaks in the response which would benefit by being dropped by 6dB - mine occurs at about 6KHz and adds a certain harshness to the sound if not EQ-ed out.

 

It can also be beneficial for certain types of music to put a mild peak in at 40Hz if the bins can handle it. smile icon

[otronics 0]

Because all venues are different...

 

People soak up sound and may require more top end/mid/even low end..

 

If you are in a marquee, more bass usually needed as its lost in the outdoors..

[Andy Westcott 0]

True enough, but in all fairness, 'environmental features' can usually be compensated for by tweaking the bass/treble controls, rather than a narrow 1/3 octave band as is offered on the better equalisers - these are better suited to tuning out descrepancies in PA systems or possibly helping deal with microphone feedback.

[otronics 0]

Indeed.

 

However, clean feed to processing is best, no matter what the app.

 

But yes, you could do it using 3 band EQ and as stated for mics, especially quick fix for feedback, it is great.