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Forte I's Woofer/Passive Driver Issue


healyc139

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Hello all,

 

I recently got a set of Forte's and I love them already.  They sound great, but I plan to get the Crite's upgrades soon. I've noticed an issue with the front and passive woofers though.. When I turn the volume up too high (higher than I usually play them) the woofers begin to kind of lose control and become very distorted, they start to shake violently and the only way to stop it is to turn the volume back down.  This only happens with vinyl also, not with CDs.  The needle/cartridge on my turntable are only about 7mo/1.5years old, respectively.  Anybody else experience this or know how I might go about fixing this?

 

This is my first post on here btw, many forums have been helpful to me in the past.  I couldn't find a post with this specific problem so I decided I would post it myself. 

 

Any help is greatly appreciated!

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DTR20 - yes the turntable is right next to the speakers actually.  Would messing around with the controls on my subwoofer be helpful?

 

Moray James - Ya neither of my amps have that, I believe.  is that something I can buy?

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Bottom Line - Poor isolation of the turntable.  Subtract the subwoofer, get a serious isolating stand,  and if needed, use a subsonic filter if you want to keep the turntable close to the speakers.  Problem is will you miss anything when you add the subsonic filter.

 

When I was a kid, I had a 12x15 room with a 4 foot deep dormer.  Kept the equipment in the dormer (second floor) including the turntable.  Used to crank my Frazier Mark Va's to crazy levels.  Never an issue tracking at light weights on cartriges like Stanton 681eee, Sure v15, and ADC cartridges.

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"Problem is will you miss anything when you add the subsonic filter."

 

Yeah, all the stuff below 20hz that is in all music and that all speakers can produce.

 

Really?

Depends on the filter and also if you are adding something like an external EQ to get the subsonic filter.  I did notice in my old Yamaha integrated (CA-800) that even with the 20hz low filter on, it did seem to roll off somewhat earlier unless it was my imagination?  Either way it will depend on when the filter cuts in and what speakers you are using along with if you have another component in the chain.  

Edited by pzannucci
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IIRC, the filter in the CA-800 was 12dB/oct at 70hz, or -3dB at 20hz, not a true subsonic filter (but better than nothing).

 

Harman Kardon (actually the vice-president of JBL was the person visiting) changed their filters after visiting my shop in the late 70's. We were the largest JBL dealer in the mid-west and had the fewest warranty problems, and they wanted to know why.

 

At the time I designed, built, and sold a 30hz, Q=1 (0dB down at 30hz) filter to go in the tape loop.

Edited by djk
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  • 2 months later...
On June 11, 2016 at 7:37 AM, pzannucci said:

Bottom Line - Poor isolation of the turntable.  Subtract the subwoofer, get a serious isolating stand,  and if needed, use a subsonic filter if you want to keep the turntable close to the speakers.  Problem is will you miss anything when you add the subsonic filter.

 

When I was a kid, I had a 12x15 room with a 4 foot deep dormer.  Kept the equipment in the dormer (second floor) including the turntable.  Used to crank my Frazier Mark Va's to crazy levels.  Never an issue tracking at light weights on cartriges like Stanton 681eee, Sure v15, and ADC cartridges.

So you think a nice isolation platform would solve the issue?  I was thinking about getting a wall mount and putting the isolation platform on that too.  Thoughts?

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