No Name Tube Amp Sent from Heaven
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Posted on Apr 08, 2009 02:56 pm
Quincysan
http://www.unitedmusicians.info
Contributor Since: Nov 11, 2007
I just bought some tube amp from a friend of mine that had been collecting dust since the mid '60s. I plugged that sucker into a Yngwie Malmsteem OD pedal and this thing has potential for stage use.
The problem: There isn't a ground on the plug, resulting in some really aggressive buzzing. Combine that with the use of single coil pickups and the noise is downright distracting.
Does anyone have experience in grounding old electrical equipment? Does anyone have a recommendation for a good noiseless single coil for my Squier 51?
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Apr 08, 2009 03:15 pm They didn't use a chaise ground back then.
You can rewire the amp yourself, it doesn't take a lot of know how. And you can't get shocked, if the cord is in your hand.
Just take a molded IEC cable. The one that goes into your computer. (Not that exact one, just one like it.)
Remove the old one. Cut off the end of the molded cable. The square end. Or the end that would normally plug into the computer. Strip the black insulation back about an inch. Then the color code should be the same in the amp.
Black = Load
White = Neutral
Green = Ground
So, connect the black to black, white to white. Remember to heat shrink the connections.
Now for the ground, drill a small hole in the amp very close to the plug. Get a self tapping screw that will go it to the hole you just drilled. Then put an eyelet on the green wire from the plug, and put the screw through it.
This will give you a grounded amp, but not a grounded signal. You may wish to put a switch on the green wire, so you can ground lift the amp.
The last step, is to remove any plastic washers that may be around the 1/4" jacks. This will allow the connector to see the new ground wire that you just installed.
And with a switch, you can add or remove the ground as needed.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 08, 2009 03:30 pm That is the most straightforward explanation I have heard yet! What should I know about buying a ground switch?
Apr 08, 2009 04:14 pm Go with the same as the power switch that is in the amp.
Apr 08, 2009 04:31 pm If you want a good hum killer for a single coil, Electro Harmonix has a Hum-Debugger. Works great!
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 08, 2009 05:42 pm Thanks Rob and Cynic
Rob: Let me see if I understand this correctly. I am grounding the amp via the green wire, and I'm adding a switch to that green wire so that I can easily turn the grounding off? Why would I need to turn the grounding off?
You mentioned that this solution would ground the amp, but it would not ground the signal. Does that mean I'll still have the hum?
I'm sure I'm missing something...
As far as the EH Hum Debugger...isn't that just masking the real issue? I have heard that noise-less single coils are a good solution, is there a reason not to use them?
Apr 09, 2009 12:52 pm There are some places that you will go to that you will find that there is about 1/2 volt between ground and neutral. That 1/2 volt will cause the amp to buzz.
So that is why just about all amps that have the chaise grounded have a lift switch.
By putting a ground on the chaise, only grounds the frame for the amp. This is why you must remove any plastic washers from the input jacks.
By doing so, you allow the instrument that you are using to see the chaise ground. That is where you ground the signal. And sometimes, depending if you are around florescent lights, you may need to ground lift the amp yet again.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Apr 09, 2009 01:09 pm I've read a few reviews on those noiseless single-coil pickups and it seems that a lot of people really don't like them compared to the normal single coils.
The first thing I'd try is to shield your guitar. For whatever reason, Fender has never made any attempt at improving the shielding on their strats and teles. Here's a good explanation on how to do it yourself:
www.guitarnuts.com/wiring/shielding/shield3.php
Otherwise, maybe look into a stacked humbucker. They put both coils of a humbucker on top of each other so they retain the footprint of a single coil. The downer to this is that the humbucker is going to be a lot hotter than your other pickups. So there's be a noticable volume difference when its active versus when its not.
What you can do as a quick fix is to use the pickup switch positions that include the middle pickup. It's wired in reverse polarity with the bridge and neck pickups. So when you select the middle pickup in combination with either the neck or bridge pickup, you get some hum cancellation.
If the hum doesn't go away in those pickup combinations, then that's a pretty good sign that most of the hum is coming from the amp.
Also, any time you start using a tube amp that's been lying dormant for a long time, its a good idea to have it serviced by a qualified technician. Not only should all of the tubes be inspected, tested, and more than likely replaced, but the capacitors will almost certainly need to be replaced. For whatever it costs to have this done, it's going to be worth it to have a stable amp that's not going to die on you in the middle of a gig. Plus it will help reduce the noise coming from the amp (failing tubes and/or failing capacitors will almost certainly add to the hum and other noise). Plus it'll tighten up the amp's sound and make it sound just like it did the day its original owner brought it home from the store.
The components inside amps age and eventually die. Preventative maintenence is the key when bringing an old amp out of retirement.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 09, 2009 02:48 pm Thanks Rob, I'm 100% clear now. BTW, I read the post on that breath controller you're building. When you finish that I hope I get a chance to listen to it...way too cool.
Tad: From your suggestions I think I'm going to shield my guitar and make sure my amp is where it should be before I invest in pickups. I know that the single coil in my Squier 51 has been changed, but the previous owner couldn't tell me with what! Also, the Squier 51 only has one single coil and one humbucker, so I'm going to count on this shielding technique to clear up the hum.
I did some research when I bought the amp that led me to believe that tubes generate the same tone until they break...and it's then and only then replacements have to be ordered. Can someone confirm or deny this with a brief explanation? What quality of my tone is affected by the capacitors? I'm going to link some pictures of this old thing for you guys to take a look at. Let me know if you can identify what the heck it is...
Also...being totally new to this, could someone give me a left to right breakdown of what I'm looking at in the picture showing the backside of my amp's components...other than the pre and power tube that's exposed I don't know what I'm looking at. Including the switch (which is not power)...could this be the ground lift? When I get home I'll have to check. That would make me feel pretty dumb...hah
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Apr 09, 2009 03:45 pm Tubes actually do degrade and change over time until they finally blink out and stop working altogether. They're not like a light bulb that works and works and then one day it doesn't work. Tubes will gradually change tonal character over their lifespan.
At first glance, I'd say that the power tube is either a 6L6 or 6550 type. The preamp tube looks a little short/fat to be a 12AX7, but you never know. If you remove the tubes, they should have the tube type printed on them somewhere. That'll be good to know when it comes time to retube it.
From what I gather, the capacitors are used to control noise and electrical feedback (not microphonic feedback) in the amp's circuits. Faulty caps will contribute to strange crackling, oscillations, and other noises coming from the amp.
I'm curious about what kind of amp that is. I'm going to look around on the net and see if I can identify it. You say you think it's a 1960s era amp? I'll look around and see what I can find.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 09, 2009 05:30 pm Yeah, I bought it off an old stoner who hadn't ever actually gotten around to playing it. That's probably why it sounds as good as it does... Frustratingly, he doesn't remember where he originally got it (must have had the GOOD stuff)
Also, what is:
-The thingy wrapped in orange tape?
-The silver doo-hickey
-The hangy-downy with wires protruding?
-The switch?
Apr 09, 2009 08:40 pm Without the schematic, I would venture a guess that the piece that is taped in orange is the power supply.
That is what takes the 110v and converts it to a lower voltage.
The other is the output transformer. The tube fires into it, and the transformer reduces the ohm load to the speaker. There are a few other things that the output transformer is doing, but that is a post for another time.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 09, 2009 08:43 pm Thingy in orange tape is a transformer. The silver thingy could be another tube hiding under that. could be a capacitor cover but I highly doubt that.
The other hangy with wires could be another trans but really not sure on that as I can't see what it has for wires.
The switch, could be ground lift without the ground leg on the power cord that is out.
It could be a mod of some kind to the tone or gain stage. Could be related to the other trans in some way. Without seeing the entire chaise (by the way Rob, is that French?) it is kind of hard to tell.
Was there a logo of some kind that got scratched off near the made in USA mark?
Apr 09, 2009 08:57 pm Wee!
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 09, 2009 09:54 pm LOL!!!!!!!!!!!!!!!
Oui?
Apr 09, 2009 10:00 pm Es tut mir leid, dass. Aber ich schreibe auf Französisch nicht.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Apr 09, 2009 10:06 pm Quote:
Also, the Squier 51 only has one single coil and one humbucker
If you have a humbucker and it's still buzzing, then there's gotta be something awry. Humbuckers are much more resistant to hum/buzz than single coil pickups (hence the name HUM-buckers!). I have a feeling that shielding won't make a huge difference on the amount of hum coming through the 'bucker, although it certainly won't hurt anything
See if there's a difference in the volume of the hum when you switch between the single coil and the double coil. If not, then the hum is most certainly coming from the amp and shielding your guitar won't help much. If there is a volume difference, then shielding your guitar will be a worthwhile endeavor.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 09, 2009 11:29 pm Alright I'm pretty sure the hum is coming from some environmental factor because I just went and played on it for a while and the hum was extremely tolerable, hardly noticeable even... I could have sworn the other day that it was obnoxious. Especially strange since everything that could be powered on in the room was powered on. The humbucker is and always has had less hum, as expected.
I'm definitely going to do that shielding thing. And I'm definitely grounding the amp one way or another. I don't like being shocked by my control surface.
I think I need to record a few licks and post a link to an mp3 to let more experienced ears weigh in...I'm pretty happy with it, but I'm always happier with better. It even sustains reasonably well...though a compression pedal wouldn't hurt.
This switch on the back is perplexing. I flip it, hear a pop like i just touched the end of the cable with it plugged into the amp, and then strum/pluck/slap/scrape/whatevericouldthinkof with hardly any difference in tone at all. I may be imagining things...but it seems like one side of the switch attacks a little bit harder.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Apr 10, 2009 10:26 am Flourescent lights, light dimmers, power outlets, power cables can all cause interference that can be picked up by your amp (or more likely picked up by your instrument cable and amplified by your amp). Grounding the amp will definitely help.
On the bright side it sounds like you found a good, quiet spot for your amp! Now you might have to move around your room with your guitar and find a nice quiet spot to stand.
Oh, and I'd bet that the switch is a polarity switch. I read that they were common on old amps with 2-prong power cords.
And for the record, I'm not an authority in any way on vintage amps. I just fell in love with tube amps so I'm just about as excited as you are about your find. I looked until my eyes crossed at vintage amp pictures yesterday but I didn't find anything that looked even close to your amp. I had no idea how vast the market for tube amps was in that era. It seems that everybody and their dog was putting out tube amps in the 1960s.
So there are no markings inside the cabinet or anything? How about that speaker...any brand markings on it? There is a mark right above the "made in USA" on the face of the amp. Is that remnants of paint, or is that just a scratch or something? I was wondering if it might be a clue as to the brand or model hehehe.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 10, 2009 05:10 pm Okay my mind just blew up. I turned on the amp again this morning and the single coil hum IS BACK. EVERYTHING IS THE SAME!!!! WHYYYYYY! The humbucker still sounds dreamy, even when I split it. All equipment is turned on, as it was when it was working just hours before. I know this is probably an "out there" thing to mention, but both last night and this morning there were electrical storms...so the weather didn't change anything. Tonight I'll try wearing a tin foil hat and holding my tongue to the roof of my mouth while hopping on my left foot. I guess it would make gigs more interesting... :)
Polarity switch sounds likely...Rob if you read this, what do you think? A switch that interrupts signal momentarily and then has relatively little effect on tone (possibly a tighter attack on one side)?
There is a model number on the speaker (I'm at work now I'll post it later)...but nothing in the cabinet or on the front. I'm curious if that little scratched up thing above made in USA is a brand name as well...but I dunno.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 10, 2009 07:32 pm
Rob, mein Deutsch sucks! Können Sie sich in Französisch auch wenn?
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 10, 2009 07:38 pm Quincysan, ya it sure looks like it was a logo or something. I've seen that dial layout before, just not remembering exactly were.
If Beerhunter see's this he might have someone he can have help identify it as well.
I'll try and email Ben here and see if he or one of his guys can ID it as well.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 13, 2009 04:55 pm Hmm hopefully Beerhunter will catch this thread. I heard it could be a Sears model from a guy at work but he isn't sure...
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 13, 2009 09:05 pm Mmmmmm, that is a thought Quincy. Although Silvertone's had a slightly different grill clothe on them. Kind of yellowish tan with a kind of silver/blue thread woven through it. But that does bare a good resemblance to them. I've owned several Silvertone's from way back then, or used them here and there. Nothing that small though.
I'm still trying to get hold of a couple guys to look at the pix as well.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Apr 13, 2009 11:56 pm Sears and Montgomery Ward were the first things I checked :)
No matches from what I saw. Something that uses that grille cloth, chicken-head knobs and a built-in footswitchable tremolo has to narrow it down quite a bit.
Quincysanhttp://www.unitedmusicians.infoContributor
Since: Nov 11, 2007
Apr 14, 2009 12:30 pm A couple more identifiers:
The only words on the amp say "made in USA" on the front panel with the tone knob, directly above the mode in use there is a silver sticker that's been ripped off. What's left of the silver sticker says "41" but there are characters before and after the 41 I think.
On the back of the speaker there is model number "583 994 232939"
On the power supply there is a model number "1002-5 662136"
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Apr 14, 2009 09:17 pm Ya, the dial layout would fit the chicken head knob for sure so that is what was on it originally.
Silvertones did use that color or similar tolex on many early models as well. But I can't remember if they ever used a darker gray faceplate like that. most were silver with either a black, red or blue logo lettering.
