18Watt.com

I have a soft rustling sound coming from my speaker. It is intermittent and is somtimes accompanied by a spanish am radio station. No Bueno! Que es problema? Or is it problemo? I dont know. Anyone out there have any advice.

Gracias.......

You are probably picking up the local radio stationthrough the pickups on your guitar. Once and a while I get the oldies station through one of my strats -> practice amp, single coils pickups are bad about that. There is a way to fix it but I cant remember off hand Ill look it up and get back to you.

The easiest way to tame the radio thing is to put a 68K resistor in line with the input right at the tube socket.

--mark

The grid stopper resistors fixed the radio interference problem. Thanks
I still have the rustling sound. It does stop when V1 is removed. I have switched tubes. My tubes are all old ones. That may be part of the problem. I am using carbon comp resistors which I understand are noisy. I do hear the rustling noise after the amp has warmed up a bit. Maybe the resistors have some part in it. I'm not sure. I will check my solder joints as suggested in a previous post. Perhaps new tubes are in order at this point also. At any rate, thanks for the help

Change the plate resistor(s) on V1.

--mark

I changed the plate resistors using carbon film on one and metal film on the other. I didnt have the same type for both. I kept the same values. I am happy to report that the amp does not have the rustling sound any more. I get a slight hiss when the volume is on 10 but other than that it is very quiet. I was getting 14 watts dissipation so I decided to change the cathode resistor from 125ohm to 220ohm and switched the cathode bypass cap from 50uf to 100uf. This change was based on the success that others on the forum have had with the problem of redplating. I am now getting about 10.5 watts dissipation per tube. This is below the recommended 12 watts. Is this bias setting too cold? I noticed the B+ went up to 369 vdc. Is this normal? Should I change the cathode resistor to another value? Any advice is welcome! Thanks!

You should be fine at that level, but you could always try 180 ohms if you're feeling the urge to solder.

--mark

Thanks for the tips. I will change the resistors to see what happens. Are you grounding the shielded part of the input wires to the input jack ground? Oh and do you like the black turret board? Look familiar? I like how it contrasts with everything that mounts to it. I was using the carbon comp resistors for the most part to be close to original specs. However, maybe my thinking is flawed because alot of the other types of components i have used are not exactly original. I was trying to be close though. Anyhow thanks again for the help.

Brian

PaulRuby wrote: Of course I like the black board! I remember makin' it...

Black boards have some of the best mojo, you know?



You didn't make it, but you did mail me the turrets.

Nice! That is a showpiece! You should mount that amp in a see through cabinet. Clear plexi or something like that.

Paul.. Thats fantastic looking...

""" Blue's gotta have some good blues mojo"""

Let see you have a blue board.. blue electrolitic caps, blue resistors,and i'm pretty sure your yellow and green heater wires.. don't yellow and green make blue when you mix them... So the yellow coupling caps have to mix in there somewhere.. Now that is the chassis you should have in the blue amp you built! Very nice work!
Richie

Brian wrote:Nice! That is a showpiece! You should mount that amp in a see through cabinet. Clear plexi or something like that.

Actually, I was told I really had to do that by one of the crazy-asses who dreamed the whole color scheme up. It'll get a clear plexi panel on the back that shows portions of the circuit, and is etched with the ToneSlut logo. Then it'll be lit from the side with LEDs so the etching glows. That's why the inside was polished and the pretty cloth-covered wire was used.

But, that's a little ways away. At the moment I'm still working on the valence panel, which is quilted maple dyed a ruby red to match the chassis. I'm getting antsy to see it all together and I'll probably mount it in the cab as soon as I can and do the view-panel at a later date. The project is taking for friggin' ever since so little is bought and I have to learn almost every task before I do it.

PaulRuby wrote:Here's a blue one in progress. Blue's gotta have some good blues mojo...

Whoa baby! That's not that pale blue, either. That's a REAL color blue. Between that and the blue jewel lamps available, I am sure I could make some extra high-mojo amps.

You gonna' have a few feet of that blue board to share with a good customer next time I run out of turrets and need to get some more?