Silverface Champ making noise when played...

[jbow]

I have had this amp for a few years, IIRC, it is a 1973. It was/is a true "closet classic". It was bought new, used a few times and then stored in, yep.. a closet.
So, it sounded absolutely wonderful until one day it started to sound like there was a low quality "noise gate" in the signal path. It still sounded nice except for the un natural death of notes or chords, they tail off then become distorted in a bad way and just die. Now it has begun to buzz more when played. It is quiet with no signal. I've tried changing the tubes twice, just to be sure. I've tried it with the volume on 10 and lower like 3 or 4. I've tried it with the treble pot and bass pot on 10 and 0, it is actually more pronounced with the volume on 10 and the tones on 0. I don't think it is worse, I think I can just hear it better. Noiseless pickups make no difference.
My first thought is to try another speaker and to look for any obvious burned looking connections or loose solder joints... past that I am clueless about what it might be or what to check.
Does anyone have an idea what I might look for. The first symptom was the bad noise gate sound.

Thanks,
Julien

[eschertron]

From the age of the amp, I'd suspect the power supply caps are leaking. From your description, I can imagine that you have a high AC (ripple) riding on your DC power. But I am no expert; hopefully someone who is will chime in.

Do you have experience troubleshooting electrical equipment? Do you have gear, such as a multimeter? If your experience is limited, I'd suggest that you take the amp to a qualified tech. The voltages inside even a cute little amp like a champ - I have a '78 - can hurt or kill you.

[Jazz P Bass]

Try another speaker.

4 ohms, 8 ohms.

It doesn't matter, as it is only a test.

If it does turn out to be a bad speaker & you go looking for a new one, keep in mind that the factory speaker is 4 ohms.

[ron vogel]

mine did that exact thing...solder joint at input jack

[jbow]

mine did that exact thing...solder joint at input jack

I have the tools and replacement parts etc. I have built several tweed amps from parts with a schematic and layout but my troubleshooting skills are not good. I have spare speakers and will research the AC ripple, not familiar with that. Will definitely check the solder joint on the input jack. Since the amp has two input jacks would trying the other jack isolate the problem or would it still present, even if I use the other jack?
I'll let you know what I find.

Thanks for the answers!!
Julien

[Fragger]

Sometimes it`s as simple as cleaning the master volume with deoxit d4.

[jbow]

Sometimes it`s as simple as cleaning the master volume with deoxit d4.

Cool, got a can of that on the shelf too! I have no static in the pots but will try that anyway... can't hurt.

Thanks for the ideas.

[ron vogel]

I have the tools and replacement parts etc. I have built several tweed amps from parts with a schematic and layout but my troubleshooting skills are not good. I have spare speakers and will research the AC ripple, not familiar with that. Will definitely check the solder joint on the input jack. Since the amp has two input jacks would trying the other jack isolate the problem or would it still present, even if I use the other jack?
I'll let you know what I find.
Thanks for the answers!!
Julien

It might, they are tied together...or it could even be the ground to the jacks...I would reflow the solder to all the joints in that area one at a time and test one at a time for improvements.

[jbow]

It might, they are tied together...or it could even be the ground to the jacks...I would reflow the solder to all the joints in that area one at a time and test one at a time for improvements.

Thanks, I will do that. I am trying to check the speaker the easy way, which is turning out to be the hard way. I have a tweed champ that I built handy but I built it with a 1/4" speaker jack for the speaker and the SF champ has an RCA jack. I have every sort of connector and cable known to man except a female to female 1/4" adapter. I am going to probably end up wiring an unused jack to wire to an RCA so I can just plug the SF into the speaker in the tweed cab... it would have been a lot easier to just unsolder the SF speaker wires and go that route but I was certain I could find a connector. Why do anything the easy way though??
I appreciate the help! I am going to brush up on draining filter caps before I go into the amp if it isn't the speaker... which I really don't think it is, but it will be if I don't check it first, lol. This is what happens when you take 5 years off from something, you forget a lot. I hope it is like riding a bicycle though... however, there is no electricity involved in riding a bike so I AM going to brush up... I got bit by one of these once and that was enough!
Will follow up,
Thanks again!
Julien

[jbow]

It was the speaker!!! I am really glad I went ahead and tried that first. I had myself convinced that it wasn't the speaker but have lived long enough so that I have learned to check the easy stuff first. I found an old RCA plug and a double strand of old wire (I save everything). I had a screw on 1/4" plug on the tweed so hooking up from the speaker output of the SF to the speaker in the tweed was easy once I found what I needed. On the first try I thought I had bad wire, then I remembered that I had pulled the rectifier and power tube from the amp. Put them back and man... I had to sit and play for a while, this amp is Soooo sweet. The bad speaker is the original Fender Special Design, Jensen I assume. The speaker in the tweed is an alnico Weber VST Signature, 8Sig-8 alnico, IIRC.
Do you have any recommendations for a good 4ohm 8" ?? I may go with another Weber, I usually like a ceramic in these type amps because they don't woof out as easily. I use a Boss Bass EQ on my bigger Fender amps because that pedal will take the phart out of any Fender with a little bass EQed out. I have the regular Boss EQ pedal too but, just to share... the Bass EQ will absolutely tame any Fender that you are trying to get a better sound out of. I'll take a look at Emi offerings, I have not tried any of the Jensen speakers from the last 10 years. Thanks for the help!!! I am a happy camper. Maybe I have another Weber 8" stuck back in the closet... will look. I do have another SF Champ that I bought to fix up, maybe the speaker in it is good. Going to get it out, fix it and finish a tweed deluxe clone I put on hold a few years ago, I got bogged down with a Mojo PT and the zener diode trick that Bruce at Mission amps was talking about. I'll check the specs on the PT and post in a thread on the 5E3 forum (but if you're familiar, I thought I'd throw it out here. I think it is an 876 Mojo tranny. Excited again!!!
I really appreciate the input and will remember it all for future use!
Julien

[ron vogel]

When I refurbed my Champ, the Weber alnico replacement went in, it's a really good pairing for that amp (for my taste anyway).

Some info on that amp:
1972 Fender Champ project - Gearslutz.com

[eschertron]

When I refurbed my Champ, the Weber alnico replacement went in, it's a really good pairing for that amp (for my taste anyway).

Some info on that amp:
1972 Fender Champ project - Gearslutz.com

+1 for Weber speakers. I put a ceramic 'blue pup' in my champ, simply because I was more interested in driving the piss out of the amp rather than reproducing the vintage sound.

[Tom Phillips]

The speaker recommendations above are all good. However, something to think about is having the original speaker reconed if you want to keep the amp looking original. I'm not anal about these things but you do have a 42 year old amp. A recone won't save you any money but it may result in a significant payback if you ever sell the amp. Anyway...now is the time to consider such things.
Cheers,
Tom

[jbow]

I have a Tweed Champ clone with a Weber Sig8-s alnico speaker in it. I also have a ceramic version of the same speaker NIB. I am going to swap the alnico from the Tweed to the SF and install the ceramic in the tweed... then I think getting a re cone on the original Fender Special design is a GREAT idea! Thanks, I will do it.
I saw something terrible yesterday. My first "real" guitar amp was a mid 60s Silvertone all tube 1485 (the head and 6x10 cab)... mine was stolen from a club... which leads to yesterday.. I saw one on Ebay for 3,799.00 Arrrrgh. To add insult to injury in 1967/68 (I don't remember) my dad bought me a Telecaster but I, in my wisdom and my desire to be Jim (Roger) McGuinne, traded the Tele in on a Hofner 12 string acoustic. Mercifully the rob broke in the neck in the late 70s... it was a horrible guitar.
OK... back to Champs...

Julien