Does no feedback loop = more hiss ?

withnail · 04-24-2007, 04:49 PM

My recent 5E3 build w/6L6s', choke, and carbon-film resistors, hisses noticably more than my other Fenders. I assume this is because the 5E3 has no feedback circuit ?? I wonder if this is normal, since this is my first Tweed Deluxe build, or should I be looking for a bad plate-load resistor ? The tubes (12ay7-v1 , 12ax7- v2 ) are not the culprits.

Mars Amp Repair · 04-24-2007, 10:17 PM

One suggestion would be to pull the preamp tubes (all but the PI driver) & see if the hiss is coming from the preamp or from the PI w/o feedback....g

withnail · 04-24-2007, 11:19 PM

Thanks , Mars for the only reply... but to me , an amp has to have more noise without a feedback circuit, right ? Short of installing one in my 5E3, can someone give me his/her observations on 5E3 hiss levels ? I can't really believe the posts that say " Man, my Tweed Deluxe is so quiet at idle, that I'm not even sure it's switched on. " I really don't care about the hiss,( small value caps across the plates can cure this... but I probably woudn't do it) I just want to know if it's normal for this circuit.

04-24-2007, 04:49 PM	#1
withnail Junior Member Join Date: Jun 2006 Posts: 15	Does no feedback loop = more hiss ? My recent 5E3 build w/6L6s', choke, and carbon-film resistors, hisses noticably more than my other Fenders. I assume this is because the 5E3 has no feedback circuit ?? I wonder if this is normal, since this is my first Tweed Deluxe build, or should I be looking for a bad plate-load resistor ? The tubes (12ay7-v1 , 12ax7- v2 ) are not the culprits.

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04-24-2007, 10:17 PM	#2
Mars Amp Repair Senior Member Join Date: Sep 2006 Location: Englewood, CO Posts: 673	One suggestion would be to pull the preamp tubes (all but the PI driver) & see if the hiss is coming from the preamp or from the PI w/o feedback....g

04-24-2007, 11:19 PM	#3
withnail Junior Member Join Date: Jun 2006 Posts: 15	Thanks , Mars for the only reply... but to me , an amp has to have more noise without a feedback circuit, right ? Short of installing one in my 5E3, can someone give me his/her observations on 5E3 hiss levels ? I can't really believe the posts that say " Man, my Tweed Deluxe is so quiet at idle, that I'm not even sure it's switched on. " I really don't care about the hiss,( small value caps across the plates can cure this... but I probably woudn't do it) I just want to know if it's normal for this circuit.

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