Check out the newest news, views, lessons and more for Fender lovers -- FenderRocks.com

ASC67 · February 3rd, 2010, 04:29 PM

So I have a Music Man HD-130 210 with the 12ax7 P.I. that I got a little while back. The previous owner installed a neg. feedback switch on the amp. Stock is negative feedback on and when you throw the switch there is no neg. feed back. My question is what exactly does this do and what exactly is neg. feedback and impact on sound without ?
Thanks

Edit:
I'm getting some answers on the Shock brothers section.

Demo · February 3rd, 2010, 07:36 PM

I'm lost. If you have the amp, why don't you know what the sound difference is with the switch on/off? Throw the switch and tell us:)

DrewB · February 3rd, 2010, 11:01 PM

A negative feedback loop takes negative energy from the speaker and feeds it back into the circuit at the phase inverter/driver. The effect is partial phase cancellation (the negative feedback is out-of-phase, relative to the "regular" signal), resulting in greater clarity and less distortion. A flick of the switch will be a better description than words, but that's what's going on. It depends on the amp, how "hot" you're running it and what you need whether negative feedback is desirable or not.

Webfoot · February 4th, 2010, 11:12 AM

I did this on a blues jr. At lower volume with no NFB, it sounded bigger and looser and a hair noiser. For the blues jr, no NFB at low to mid volumes made it a boutique amp. Also increases the touch sensitivity. Got rid of the boxy sound.

But if playing with a lot of people and loud, you probably want NFB because it keeps the amp tone more focused and less extreme excursions especially on the low end (or at least turn the bass down).

You can also put in a variable resistor and dial in what you like.

robt57 · February 4th, 2010, 11:15 AM

Quote:

Originally Posted by Demo

I'm lost. If you have the amp, why don't you know what the sound difference is with the switch on/off? Throw the switch and tell us:)

I think he meant the electro mechanics, he obviously can hear it.

Donnie55 · February 4th, 2010, 11:22 AM

Negative feed back loop... Usually the missing link in amps claiming to be class A.

ASC67 · February 4th, 2010, 11:46 AM

Quote:

Originally Posted by robt57

I think he meant the electro mechanics, he obviously can hear it.

thanks, I wasn't going to state the obvious

February 3rd, 2010, 04:29 PM	#1 (permalink)
ASC67 Friend of Leo's Join Date: Jul 2008 Location: Minneapolis, MN. Age: 46 Posts: 3,487	Negative feedback So I have a Music Man HD-130 210 with the 12ax7 P.I. that I got a little while back. The previous owner installed a neg. feedback switch on the amp. Stock is negative feedback on and when you throw the switch there is no neg. feed back. My question is what exactly does this do and what exactly is neg. feedback and impact on sound without ? Thanks Edit: I'm getting some answers on the Shock brothers section. __________________ Steve Last edited by ASC67; February 3rd, 2010 at 07:09 PM.

February 3rd, 2010, 11:01 PM	#3 (permalink)
DrewB Tele-Afflicted Join Date: Feb 2005 Location: Independence, MO Posts: 1,591	A negative feedback loop takes negative energy from the speaker and feeds it back into the circuit at the phase inverter/driver. The effect is partial phase cancellation (the negative feedback is out-of-phase, relative to the "regular" signal), resulting in greater clarity and less distortion. A flick of the switch will be a better description than words, but that's what's going on. It depends on the amp, how "hot" you're running it and what you need whether negative feedback is desirable or not. __________________ There is no substitute for Sound Pressure Level

February 4th, 2010, 11:22 AM	#6 (permalink)
Donnie55 Tele-Afflicted Join Date: Jul 2009 Location: Nashville Age: 57 Posts: 1,576	Negative feed back loop... Usually the missing link in amps claiming to be class A. __________________ www.myspace.com/redtele2 http://www.reverbnation.com/#/redtele If the music business was easy, then smart people would do it.

Sponsored Ads	#
Forum Sponsor Sponsored posting Join Date: March, 2003 Location: Forum HQ Age: Posts: N/A	Sponsored by...

February 3rd, 2010, 07:36 PM	#2 (permalink)
Demo Tele-Meister Join Date: Apr 2007 Location: Reno, NV Age: 59 Posts: 375	I'm lost. If you have the amp, why don't you know what the sound difference is with the switch on/off? Throw the switch and tell us:)

February 4th, 2010, 11:12 AM	#4 (permalink)
Webfoot Tele-Holic Join Date: Jan 2007 Location: Oregon Posts: 773	I did this on a blues jr. At lower volume with no NFB, it sounded bigger and looser and a hair noiser. For the blues jr, no NFB at low to mid volumes made it a boutique amp. Also increases the touch sensitivity. Got rid of the boxy sound. But if playing with a lot of people and loud, you probably want NFB because it keeps the amp tone more focused and less extreme excursions especially on the low end (or at least turn the bass down). You can also put in a variable resistor and dial in what you like.

Check out the newest news, views, lessons and more for Fender lovers -- FenderRocks.com

IMPORTANT:Treat everyone here with respect, no matter how difficult! No sex, drug, political, religion or hate discussion permitted here.