Slight hiss from my '71 deluxe reverb. Amp techs??

lenny · March 21st, 2005, 01:03 PM

My new(to me) Deluxe Reverb has a slight hiss to it.
Is hiss a fixable problem? Or do i just have to live with it.
It's very slight, and is not noticeable most of the time, but i think it would be an issue if i recorded with it.
What causes hiss in these amps? It was just recapped(partially perhaps, i have the old caps if it's important i can list which ones were replaced) and has new tubes.
??
tnx in advance
:)

Glen W · March 21st, 2005, 01:17 PM

A slight hiss is pretty much normal. If it's bad enough to be a nuisance, and swapping out preamp tubes doesn't fix it, then it might be the plate load resistors on the preamp tubes need changing out.

lenny · March 21st, 2005, 08:01 PM

thanks glen, i do remember reading about resistors and hiss b4
i'm playing "ramblin fever" on my strat thru it right now as a matter of fact, sounds sweet!
:)

Stan Martin · March 22nd, 2005, 04:45 PM

Quote:

Originally Posted by Glen W

A slight hiss is pretty much normal. If it's bad enough to be a nuisance, and swapping out preamp tubes doesn't fix it, then it might be the plate load resistors on the preamp tubes need changing out.

change the 100k 1/2 watt to 100k 1 watt and it should decrease the hiss factor quite a bit.

DADGAD · March 22nd, 2005, 05:24 PM

You can mod the amp to reduce the hiss, at which point you can kiss the original tone goodbye. I would live with the hiss. When you're playing, the hiss is no problem.

IMHO, YMMV, etc....

Gary

Stan Martin · March 22nd, 2005, 05:52 PM

Quote:

Originally Posted by DADGAD

You can mod the amp to reduce the hiss, at which point you can kiss the original tone goodbye. I would live with the hiss. When you're playing, the hiss is no problem.

IMHO, YMMV, etc....

Gary

save the 1/2 watt if you want to sell the amp.
you're not changing component values, you're changing the wattage rating, thereby reducing hiss.

telewacked · March 22nd, 2005, 08:25 PM

I have the same issue with my mid-70's DR. It hisses a lot louder than my same era VR. A tech went thru it and recapped and retubed it a few years ago, and I've swapped around tubes quite a bit without any luck. Would just changing the aforementioned resistors to the same value resistor be something worthwhile to try - perhaps the values have drifted or were never correct?
Or, are there other items to look at - what makes one amp of a particular type hiss while another is quiet, assuming the same large component such as tubes and perhaps speakers?

Stan Martin · March 22nd, 2005, 08:32 PM

Quote:

Originally Posted by telewacked

I have the same issue with my mid-70's DR. It hisses a lot louder than my same era VR. A tech went thru it and recapped and retubed it a few years ago, and I've swapped around tubes quite a bit without any luck. Would just changing the aforementioned resistors to the same value resistor be something worthwhile to try - perhaps the values have drifted or were never correct?
Or, are there other items to look at - what makes one amp of a particular type hiss while another is quiet, assuming the same large component such as tubes and perhaps speakers?

absolutely. the 1 watt 100k will diminish the hiss.

Glen W · March 22nd, 2005, 10:21 PM

Not sure of the year, but didn't Fender switch to 1 watt plate load resistors sometime during the '70s?

lenny · March 23rd, 2005, 01:34 PM

ok, so if i decide to take my amp apart and replace the preamp plate load resistors...
i can solder. i can find them
i cannot however, work safely on my amp because i don't know how to drain the charge out of the capacitors.
how can i do this?

Stan Martin · March 23rd, 2005, 01:47 PM

of the 1st or 2nd preamp tube(norm or vibrato ) and clip it to the chassis. make sure standby is in PLAY or off mode. Leave it there while you are soldering away.

I hate to say this, but make sure your amp is unplugged from the wall first

good luck

lenny · March 23rd, 2005, 08:05 PM

hmm, the chassis is only grounded if it's plugged in. sorry to be a pain in the arse, but clipping to an ungrounded chassis makes less sense to me than clipping it to some sort of ground, to let the current flow to...
??
and thanks to all for your input, very helpful all around :)

El Capitan · March 23rd, 2005, 08:44 PM

Quote:

Originally Posted by lenny

hmm, the chassis is only grounded if it's plugged in. sorry to be a pain in the arse, but clipping to an ungrounded chassis makes less sense to me than clipping it to some sort of ground, to let the current flow to...
??
and thanks to all for your input, very helpful all around :)

There is more you need to learn.

UNPLUG THE AMP.

Put on eye protection, take multimeter readings at the caps. Now "ground them, and watch sparks fly", take another reading....
install, alligator clip as previosly mentioned and solder away.....

Oh yes one more thing......
UNPLUG THE AMP

The chassis is the ground plane for the DC voltage in the amp, where does it go? well it can't dissapear, so it has to go somewhere, but we/don't have time for a complete course on DC electrical theory

Just rest assured, that your multi-meter (FLUKE) isn't lying to you if you know how to use it.
Good luck on your journey.
El

March 21st, 2005, 01:03 PM	#1 (permalink)
lenny Banned Friend of Leo's Join Date: Jan 2004 Location: New Haven, CT. USA Posts: 3,219	Slight hiss from my '71 deluxe reverb. Amp techs?? My new(to me) Deluxe Reverb has a slight hiss to it. Is hiss a fixable problem? Or do i just have to live with it. It's very slight, and is not noticeable most of the time, but i think it would be an issue if i recorded with it. What causes hiss in these amps? It was just recapped(partially perhaps, i have the old caps if it's important i can list which ones were replaced) and has new tubes. ?? tnx in advance :)

March 22nd, 2005, 05:24 PM	#5 (permalink)
DADGAD Tele-Holic Join Date: Mar 2003 Location: Palmdale, CA Posts: 801	You can mod the amp to reduce the hiss, at which point you can kiss the original tone goodbye. I would live with the hiss. When you're playing, the hiss is no problem. IMHO, YMMV, etc.... Gary __________________ "I need to learn some new scales and stop obsessing about this stuff." http://www.myspace.com/slickshoes

March 22nd, 2005, 08:25 PM	#7 (permalink)
telewacked Tele-Meister Join Date: Mar 2003 Location: Shawnee, KS Posts: 243 11 Photos	is there any other items to trouble-shoot? I have the same issue with my mid-70's DR. It hisses a lot louder than my same era VR. A tech went thru it and recapped and retubed it a few years ago, and I've swapped around tubes quite a bit without any luck. Would just changing the aforementioned resistors to the same value resistor be something worthwhile to try - perhaps the values have drifted or were never correct? Or, are there other items to look at - what makes one amp of a particular type hiss while another is quiet, assuming the same large component such as tubes and perhaps speakers?

March 22nd, 2005, 10:21 PM	#9 (permalink)
Glen W Tele-Holic Join Date: May 2003 Location: CT Age: 60 Posts: 815 12 Photos	1 watt Not sure of the year, but didn't Fender switch to 1 watt plate load resistors sometime during the '70s?

March 23rd, 2005, 01:47 PM	#11 (permalink)
Stan Martin Tele-Holic Join Date: Mar 2003 Location: Pepperell Posts: 818	take a jumper wire( w/alligator clips) from pin1 of the 1st or 2nd preamp tube(norm or vibrato ) and clip it to the chassis. make sure standby is in PLAY or off mode. Leave it there while you are soldering away. I hate to say this, but make sure your amp is unplugged from the wall first good luck

March 21st, 2005, 01:17 PM	#2 (permalink)
Glen W Tele-Holic Join Date: May 2003 Location: CT Age: 60 Posts: 815 12 Photos	A slight hiss is pretty much normal. If it's bad enough to be a nuisance, and swapping out preamp tubes doesn't fix it, then it might be the plate load resistors on the preamp tubes need changing out.

March 21st, 2005, 08:01 PM	#3 (permalink)
lenny Banned Friend of Leo's Join Date: Jan 2004 Location: New Haven, CT. USA Posts: 3,219	thanks glen, i do remember reading about resistors and hiss b4 i'm playing "ramblin fever" on my strat thru it right now as a matter of fact, sounds sweet! :)

March 23rd, 2005, 01:34 PM	#10 (permalink)
lenny Banned Friend of Leo's Join Date: Jan 2004 Location: New Haven, CT. USA Posts: 3,219	ok, so if i decide to take my amp apart and replace the preamp plate load resistors... i can solder. i can find them i cannot however, work safely on my amp because i don't know how to drain the charge out of the capacitors. how can i do this?

March 23rd, 2005, 08:05 PM	#12 (permalink)
lenny Banned Friend of Leo's Join Date: Jan 2004 Location: New Haven, CT. USA Posts: 3,219	hmm, the chassis is only grounded if it's plugged in. sorry to be a pain in the arse, but clipping to an ungrounded chassis makes less sense to me than clipping it to some sort of ground, to let the current flow to... ?? and thanks to all for your input, very helpful all around :)