Built my first 5E3! Comments/questions

[mbratch]

I've not played a 5E3 before. This is a great amp and I love it. And it worked the first time!

But, I do have a slight 60 or 120Hz hum on both channels (not sure which it is). Can be controlled with the volume, so it's in the input section somewhere. When the amp's warmed up, it's negligible at lower volumes but is more noticeable at higher volumes. I was hoping to get this quieter as some people here have done successfully. Here's a link to another post with the pics: my 5E3.

A couple of other questions:

1) I assume it's normal for the volume to be very non-linear? About 10-90% of the volume seems to be between 2 and 3 or 4 on the dial.

2) A pretty dark-toned amp. I can't imagine using the "Normal" channel. It sounds quite subdued even with the tone all the way up. With a single coils or humbuckers, I gravitate to the "Bright" channel and have the tone on about 9. BTW, I have a Weber AlNiCo Sig 12S speaker.

3) New Weber AlNiCo Sig 12S. It's got a nasty resonant buzz on low notes A through E. I'm pretty sure it's the speaker as I tried a different speaker in the cab and no buzz, and set the Weber speaker outside the cab, hooked up, and it still buzzed. Is this normal pre-break-in behavior for this speaker?

Overall I'm really psyched about the amp. It's got a really nice edge-of-breakup bloom to it at moderate volume. I'm not sure it will work yet in my gig scenario, but I'm going to give it a try.

[stingray_65]

Kudo's on you build!

I'f you're happy with it now, your gonna love it when it's dialed in.

60 hZ buzz:

is the buzz there when no instrument cables are plugged in?

I ask because I'm not infering your cables are bad, but with no cables plugged in (assuming here you used 12A style jacks and they are wired correct) your input is shunted to ground.

if the hum is still there this may indicate heater wiring

if it goes away it may suggest the input wires are picking up something, I used shieled wires with the shield grounded at the jack only.

I've said it before, operating the vol/tone knobs on a tweed fender is like operating a Ouiji board so the non-linearity you are experincing will change whith regard as to where the other two knos are set.

any way you figure a way around it and it looses a lot of tweed mojo, learn to love it like an ugly child and you'll be happier

By the very nature of the amp it is dark toned and made worse by humbuckers.

there are mods to remedy this. my son had thought I had built him a Bass amp when he first fired his up.

I built mine as a head instead of a combo, but I have a Weber AlNiCo Sig 12s in a largish open back cab and that is anyone who has played this amp's favorite speaker. I've never noticed a buzz at all

I've never had to send a thing back to Ted at Webers, but it is my understanding he's pleasant to work with on things of that nature. I would drop him a line and tell him you're scenario, no one knows those speakers better than him, he might have an insight to what is going on. on that same note, have you tried that speaker on a different amp?

The thing I loved most was hearing my son's friends say things like "OMG that sounds better than my line 6 with a distortion pedal" "where is the overdrive switch" and my all time favorite "If I took apart the TV in my grandma's basement could I build one out of the parts?"

I have to say I was glad I built the 5E3 as my first tube amp project. unfortunatly I caught the bug and hang out on this forum alot because it was so rewarding on so many levels.

Ray

[mbratch]

Thanks Ray. You responded to each of my points!

Some info about the hum:

1) It changes with the volume control. If volumes are off, the hum is off. The louder the volume, the louder the hum.

2) The hum is exactly the same whether I have an instrument plugged in or not. The jacks are wired correctly, shunted to ground when unplugged.

3) The normal channel hum (ie, the hum that appears with increase in normal channel volume) is, at least at first, louder or buzzier than the bright channel hum.

4) Overall the hum seems to subside after the amp's been on for quite awhile (I'm double checking this, sounds odd).

5) I played with moving wires around inside the amp with a chopstick while the amp was on and couldn't change the hum much. It blipped when I touched an input signal wire to V1, but would subside back to "normal" when I untouched the wire.

6) I tried a couple of quick mods to see if I could alter it: (a) I tried moving the back-of-pot ground buss chassis tie from the jack side to the PT side, and (b) I tried a shielded audio cable (ground on one side) from the first volume pot to V2. In both cases, there was no distinguishable change to the hum.

7) See my pics at the link above to see how I have it wired. The heater wires are well away from signal wires (as much as possible). Although I kept them close to the chassis. [EDIT] I just tried elevating the heater wires rom the chassis.. Absolutely no impact on the hum.

Although the amp is dark, I think it might still be OK even with my fattest sounding guitar (ES347) as long as I use the bright channel and keep the tone turned up.

I love the comments about the amp from your son's friends. Thanks for sharing those.

I just sent a note to Ted explaining the sound. I wasn't sure whether I should contact him or the place that sold me the kit including speaker. I asked him what I should do in that case. This buzz actually happened to me with one other AlNiCo Sig speaker (an 8S I bought two years ago) and he graciously swapped it out for me. I've got one of his non-Sig ceramic speakers and it's great.

You're right about the amp kit bug. This was a lot of fun and I learned quite a bit reading technical info on this board just with a few questions I had while building. My next kit will be something EL84 based.

[stingray_65]

what puzzles me is 5E3 by the nature of thier design are pretty quiet.

I've seen your pics of your builds in another post and off hand your lead dress looks good, however it was only a cursory look. perhaps someone with a keener eye than mine might spot a glaring fault.

it had ocurred to me too that one place hum can come from is the heater wiring from V1 and V2. Make sure that the wire that goes to pin 9 of V1 goes to pin 9 of V2, the same for pins 4and 5. also make sure that this is true for V3 and V4. the wire from pin 2 lands on pin 2 of the 6V6's.

what happens is if there is heater induced hum it is inverted in the other tube in the same manor and by the nature of a Push Pull amp it actually cancels.

I couldn't help but see to you have the ground switch connected. Is this being used as the standby switch or have you wired it as the original schematic with a death cap?

if the later you might want to reconsidder, the term death cap is no misnomer and is foolish to use (IMHO).

Ray

[mbratch]

it had ocurred to me too that one place hum can come from is the heater wiring from V1 and V2. Make sure that the wire that goes to pin 9 of V1 goes to pin 9 of V2, the same for pins 4and 5. also make sure that this is true for V3 and V4. the wire from pin 2 lands on pin 2 of the 6V6's.

Hey good catch. You may have something there. I was seeing that on the schematic but when I got to twisting the wires I stopped paying attention to which side was which. I'm going back to look at that...

I couldn't help but see to you have the ground switch connected. Is this being used as the standby switch or have you wired it as the original schematic with a death cap?

if the later you might want to reconsidder, the term death cap is no misnomer and is foolish to use (IMHO).

Yeah, it's a ground switch. And there's a death cap in there (hard to see in the pic, it's under the switch). The kit came that way and was diagrammed that way. So I left it. I was planning on rewiring as a standby or getting a 3-way switch used like the 70's SF amps.

[conisat]

Just had a look at your amp, nice build, good looking cab.
As to the hum, looking at the pics your transformer doesnot seem to have a centre tap on its winding and that will lead to a loud hum. This is easily sorted on the 6.3v winding a artificial centre tap can be created via two 100 ohm resistors to ground (this will also need to be done on 5v winding if it is not being used).

[mbratch]

Just had a look at your amp, nice build, good looking cab.
As to the hum, looking at the pics your transformer doesnot seem to have a centre tap on its winding and that will lead to a loud hum. This is easily sorted on the 6.3v winding a artificial centre tap can be created via two 100 ohm resistors to ground (this will also need to be done on 5v winding if it is not being used).

Thanks for the comps on the build.

My diagram shows I have two 100 ohm resistors as you describe. They're hard to see in the pic, as they're obscured by the wiring coming off the pilot. So I should be all set there.

The hum is not very loud.

[mbratch]

it had ocurred to me too that one place hum can come from is the heater wiring from V1 and V2. Make sure that the wire that goes to pin 9 of V1 goes to pin 9 of V2, the same for pins 4and 5. also make sure that this is true for V3 and V4. the wire from pin 2 lands on pin 2 of the 6V6's.

The good news: you were right that I may have had them mixed up. I did, so I just fixed them.

The bad news: the hum is still there.

[stingray_65]

I've had a little closer look at your pix

from what I can see you did follow the correct heater wiring on your preamp stage
I did see that on V2 you have your wires very close to your heater wires (see pic)

pull those wires so that they are coming off the socket almost vertically and they wont cross the heater wiring at all. you did well to cross them at 90 degrees, but not even comeing near them will be better.

if that does it, shorten those wires a bit epecially pin 7 and 2 as they are most sensitive to picking up stray signals

it's tighter to do and requires you rout the heater wires first but I rout the heater wires across the middle of the socket and never around it.

Ray

[mbratch]

Again, thanks very much Ray. I appreciate the time you've spent working with me on this problem.

I'll work in the area you described. I thought I had tried a test already where I lifted those wires up above the heater wires and got little improvement, but I'll go back and be a little more rigorous and see what happens.

Mark

[mbratch]

OK so I did some changes. I modified the heater wiring so that it goes more directly from the pilot light to the first power tube (avoiding entanglements with the OT wires, etc). Then for the pre-amp section, I ran the heater wires up the middle, arched slightly, and no more signal wires cross them.

Alas. Still hum.

I did notice one other thing I wasn't sure was normal. Even with both volume pots down, there is a very slight hum. It's not much, but there. If I touch the chassis with my hand, it goes away. Again, it's fairly quiet, but definite. Not sure what that means...

[tubeswell]

Heya Ray - bingo (I just made exactly the same comments over on Mark's other post).

[tedweber]

3) New Weber AlNiCo Sig 12S. It's got a nasty resonant buzz on low notes A through E. I'm pretty sure it's the speaker as I tried a different speaker in the cab and no buzz, and set the Weber speaker outside the cab, hooked up, and it still buzzed. Is this normal pre-break-in behavior for this speaker?

Sounds like it got beat up in shipping. 86 it, email me your address or order number and I'll send you a replacement.

Sorry for the problem with it. I'm a fan of FedX, and will not use UPS under any circumstances, but sometimes even FedX seems to have a contest to see how far they can throw something. Very frustrating.. and costly.

Ted

[Five_E35]

Five_E35

I assume you flipped the ground switch, but disconnecting that cap may help. If you intend to keep it, it should be a UL-approved class Y1 or X1 cap. These are designed to fail open, are commonly used in surge strips with noise filtering, so if you plug into one of those you don't really need it in the amp.

Have you tried different tubes in V1 & V2 or swapping them to see what happens? Sometimes tube shields help, occasionally they make it worse. Is the back panel of the cab shielded and grounded? If not try a heavy piece of foil over the back the chassis, but be extra carefull not to short the standby, power, and pilot light terminals.

In mine, I found it would hum when both volumes were up at the same settings, if the plate voltages on each side of V1 were more than about 10 volts apart. I'm not sure how plate voltage relates to preamp tube matching, but my guess is this has something to do with the shared cathode.

[ho-mayed-stuff]

Have you tried moving the amp to a different place in the room or to a different room to isolate the humm?

Do you have the back on the amp when you get the humm or is it open?

I also copper foil shield the back cover completely over the entire length and width of the cahssis.

The concentration of volume in a small range in the pots sounds like linear taper pots. I've had good luck and predictable control with 1Meg Audio taper pots even with the interactive nature of the design.

Try setting the unused ckt. volume control somewhere between 4 and 7, it's kind of a sweet spot.