5e3 Build works well, but the "interactive controls don't change the tone"

[Professor3]

Hi,
I just nearly finished up a 5e3 build I had started many years ago. After cleaning some jacks and adding a new ground buss using Rob Robinette's website, the amp works really well... mostly. I've owned a vintage 5e3 long ago, and I've even heard mine work correctly at one point. I've checked the wiring over and over. I've checked voltages on the preamp (slightly lower than on rob robinette's site with a 5e3, but only slightly) I've replaced both preamp tubes. Checked and rechecked my solder connections. Checked the wiring on the jacks. They're working fine, and shouldn't relate to this problem, but just in case you ask.. Both channels work fine, and aside from a microphonic power tube, the amp sounds very good. The problem is that the volume control of an unused channel does not change the tone of the amp. I want my mid dip and it's not there. The volume control of the unused channel does lower the volume of the used channel starting around ten, but it does not alter the tone. I've spoken to one other guy who has a similar problem with his, and I've read a post on the net from someone who has the same problem. I believe the controls might have been working fine before I put in the new ground buss. The chassis had been sitting around for 20 years and it took a while to get the jacks cleaned and working right. I re-soldered the connections from the input jacks and volume controls on the board at that time. I've pulled the board to check it out, but I couldn't see anything wrong. I've tried to give y'all all the info I could. I have searched the forum for this particular topic, and all I could find were posts from people who didn't understand the interactive controls. Their amps were working, and they didn't understand why the controls were so interactive. I do know what it's supposed to sound like and mine are not interacting correctly. This is my first post ever. Sorry if I've left anything out. What could cause just this one feature of the amp to stop working? Everything else works exactly as expected. Any help would be greatly appreciated.

[Willabe]

Hi and welcome. 

I know you checked and triple checked your wiring but, if the 2x volume controls and tone control are wired correctly, it has to work.

This is a very good way to double check your wiring;

http://el34world.com/Forum/index.php?topic=17701.msg178630#msg178630

Attached is an edited layout drawing showing the signal secondary path to ground. As you turn the un-used channels volume up, the signal goes around the 1M pots resistance, then through the .1uF coupling cap, through the 100K plate R then through the B+ filter cap to ground. The .1uF coupling cap sets the mid frequency dip.   

[Professor3]

Thanks very much for the reply. Although I didn't have a highlighter handy, I did read the post about this excellent method. In lieu of a highlighter, I traced through the circuit one connection/component at a time using both a layout, and a schematic to try to find my mistake. (several times) I just can't find it. It must be something small as absolutely everything else works exactly as expected. (I'll get a highlighter today and try again) I guess what I was hoping for was some idea of where to look. I'm hoping I don't have to disconnect the pots and tubes and completely pull the board, but I'm thinking the problem must be under the board. Maybe I accidentally shorted a connection under the board with solder when I re-soldered some connections on the eyelet board. I will go through the process again and find where I made my mistake. Thanks again for the reply. I'll let you know what I found when I find it. Maybe my hearing has gotten so bad that it's actually working and I just can't tell. 

[Joe6v6]

Maybe my hearing has gotten so bad that it's actually working and I just can't tell.

Maybe not your hearing but the interaction is very subtle until the unused volume control gets to 9-1/2 - 10 then it should become obvious. try putting the channel your plugged into at around 5 or 6 then play with the unused volume at 9 - 12 & see what happens.  .   Joe     

[Professor3]

I was "sort of" joking about that. My hearing isn't as good as it used to be, but It still works. I've owned a vintage 5e3 at one point in the distant past. I know how they are supposed to work, but mine is confusing the heck out of me. It's not like there's no interaction at all. Turning the unused channel volume past 10 causes the volume to drop as expected, but there is no tone change before the volume drop. On my original one, and several clones I've played through in the past, the shift in the mid is very apparent as you sweep the pot on the unused channel. I don't get the mid dip in the center range of the unused channel volume control. I took it to the guitar repair shop I work at, because my boss is starting to get interested in my project. He could hear no difference in the tone as I swept through the range of the volume control on the unused channel either. I can't turn the amp up at home as the amp is a bit too loud for my wife's sensitive ears. I'm still thinking I may have inadvertently shorted a connection under the board when I re-soldered some of the eyelets and changed the grounding scheme a little. I originally wired this chassis up about 20 years ago, but I never finished it. I had all kinds of noise issues when I first turned it on, jacks were a little corroded and some tubes were bad. I focused more on those issues at first as I was trying to bring it back to life. The interaction was more apparent before I reflowed those eyelets. I'm going to check my wiring again, using the highlighter method as Willabe suggested. I'll pull the board and double check underneath if I still can't find the problem. I guess what I was looking for in my post was a direction to look as far as a bad component or an under the board short that might cause these symptoms. Absolutely everything else on the amp works exactly as expected. Tone control works and also adds gain. The amp is loud and strong. The bright channel is brighter than the normal channel. It's pretty quiet even at volume. The volume is off before around 2 and ramps up really quickly after that. Volume is near max around 4 or 5. Above 5 mostly just adds more gain and compression. The jacks work as expected. Everything but the one thing I love most about them. I'm planning on pulling the board and going through everything later this week. I'm going to figure this out. I am strongly considering building my next one using the Hoffman turret boards though. Seems like a much better way to wire one up, and even though I haven't figured my problem out yet, I really appreciate the help I'm getting from forum members. Thanks very much. I'll post to let everyone know what I did wrong once I find my mistake. I have read one online post from somebody who had this exact problem. One of the other guitar players in the blues/rock band I play in also has exactly the same problem with his. (we actually built both of the chassis at the same time 20 years ago, but mine never got finished.) The amp works fine, and he's got the best tone in the band, so it's not really a problem for him. I just have to get to the bottom of it. Thanks again for the input. I hope to post about figuring it out SOON!     

[sluckey]

The interaction was more apparent before I reflowed those eyelets.

Since it worked as you expected before you "fixed" it, you should start by examining the work you did.

[Professor3]

Thanks Sluckey, I've read several of your posts on other topics, and I was kind of hoping you might chime in. I also thought that the fact that it seemed to work before I reflowed those connections might be a clue, So I went over my wiring using the fender layout and a highlighter yesterday. Now I'm wondering if I just imagined that it was working. The amp had sat untested for 20 years. It was in a state of neglect when I first fired it up. Jacks were dirty, tube sockets were noisy. One of the preamp tubes was shot. It was pretty gnarly when I started trying to breathe life into it. I'm beginning to think maybe I heard them working because I wanted to hear them working. Anyway, I checked all the connections above the board and I loosened the pots and jacks and pulled the front of the board up so I could check the connections under the board paying special attention to the connections I had touched up. I brushed the back of the board clean and blew compressed air into the chassis in case there was an errant piece of wire or solder that was shorting somewhere. Willabe mentioned "The .1uF coupling cap sets the mid frequency dip.", so I've ordered new coupling caps just in case they've drifted. I'm not sure that would make a difference, but it's possible some components drifted over time. I added the Rob Robinette switchable negative feedback and pre PI master volume a couple days ago. I know I probably shouldn't start modding before I've got the problem figured out, but my problem is in the pre-amp. Even though I'm not hearing what I expect re the interactivity, this amp still sounds incredible, and I'd like to be able to use it! At 62, I play more gigs at BBQ joints than dancehalls, so I really wanted to add the master volume. At 3, the darn thing would get me kicked out of a restaurant .

I did change the grounding scheme at the same time I re-flowed the connections. I used a heavier ground buss wire and grounded the preamp to the ground of an input jack as Rob Robinette suggested. Could my problem lie there somewhere? Once again, I sincerely appreciate input from anybody. I'm looking at this as a fun challenge. The amp already sounds great, and it gets a little better with each new tweak. I don't have to make this feature of the amp work, but I'm enjoying chasing the gremlin. I consider everything that gets suggested, and I'm trying to give y'all all the information I can. VERY IMPORTANT! Thank you, thank you, thank you for your input! I don't want to impose on anybody. I appreciate your help, but I don't expect it or take it for granted. I am listening intently to everything you say and doing what y'all tell me to do. If you're not having fun trying to help me figure this out, please don't put yourselves out. I'm digging the challenge, but y'all may get tired of my "novelette" sized posts.

[sluckey]

Post some hi-rez pics. Nice close-ups that clearly show the pots, the board, and the interconnecting wires. All in one sharp focused, well lit photo. Close-up of the entire chassis will be helpful too.

What taper are your pots? That will make a big difference in what you remember and what you have now. Should be able to get the same interactions but they won't occur at the same number on the dial. Most people use audio/log taper because that's what most volume pots are. But I don't know which pots Fender used because they didn't say on their schematic.

[Professor3]

Thanks. I've got students tonight, and the amp is currently buttoned up. I'll get some good pics posted tomorrow. You realize of course that now I'm going to have to go over the circuit one more time and make sure my wiring looks okay. I've been moving stuff around to reflect slightly different layouts (Weber, Fender, Robinette) as I try to find the problem. I'll have to make sure the wiring is clean. By the way, thanks for showing your amp stand on your web site. It looks like a good one. We're going to be making a couple up at the guitar repair shop so the boss and I can each build a 5e3 soon.

[labb]

Just a thought on a new build. The 5E3 is a fun amp. I have built a couple of them and a couple of the 5B3's. Lots of fun to play with. But, if you are really into the Deluxe amps take a look at the AB763 circuit. Sluckey's AB 763 Lite. it is an easy build and, I think, puts all of the others to shame. Leo got it right with this one. If one has a Marshall Plexi and any of the Fender AB 763 amps I can't imagine how it could get any better. JMO

[Professor3]

I'm a huge fan of AB763 amps. I was thinking about building a Deluxe Reverb next. I will definitely check out Sluckey's amp. I'm still building from kits at the moment. Trying to wrap my head around how everything works. I'm not sure I'm ready to stray too far from a kit build yet, but I will look into it. I'm building the second deluxe for my best friend. I was going to finish putting this one together and give it to him a while back, but couldn't part with it once I got it working. I had a small collection of blackface amps back in the early 90s. I got on a channel switching kick for a long time and eventually sold them all. I was playing on bigger stages and doing lots of classic rock back then, but I sure wish I had kept a couple of them.

As long as people are replying to this post, I'm flummoxed about something. As I remember it, the interactive controls cause a dip in the mids partway through the sweep. I've been reading a lot about a quote from Gerald Weber about how they worked. That's how I remember the interactive controls. They affect the midrange and thin out or fatten the tone. I went on YouTube tonight to find a video about the 5e3, and every example I could find showed the unused volume control dumping the volume after it got to 10 or 11, but didn't exhibit any change in the tone till then. Mine does that, but it doesn't change the midrange content. Is my memory just flawed? 

[sluckey]

Is my memory just flawed?

Maybe. Memory is a tricky thing. Especially when you are senior. My brother and I reminisce about significant shared childhood experiences. I'm always amazed at how differently we remember things. I swear he just doesn't remember correctly. But am I correct?      

Those hi-rez pics I asked for may at least let us figure out if the amp is wired correctly. Once we determine the amp is in fact wired correctly, you may need to talk it over with your brother.   

[Willabe]

 

[Professor3]

Ouuuuuch! Wether I have a wiring problem or not, that was great! And right on the money. About to start teaching classes right now, but I'll be back in the shop this afternoon and I'll get some good pics out to y'all so you can laugh at my wiring. You know, at my age, the hands start to shake

[Professor3]

The more I research this, the more I think the amp is working as it should. It sounds amazing and the mods make it way versatile as well. Just can't get this Gerald Weber article out of my head.

"This can be used to your advantage, especially if you have an A/B box. Set the normal channel all the way up and the instrument channel halfway up. Use an A/B box to select between the microphone and instrument channels.

Here’s what will happen: When you select the instrument channel, you will get a fabulous clean tone. Since the instrument volume is turned halfway, you are not really overdriving the instrument channel that hard and since the microphone’s volume control is turned full up, you are scooping out the mids in the instrument channel. This gives you that “better than blackface Twin” clean tone-to die for.

When you select the microphone channel (which is turned all the way up), you will get a fabulous lead tone. For one thing, you will be overdriving the output stage and because the instrument channel is halfway up, you will be boosting the mids as much as possible. This results in a thick, creamy, cello-like tone with incredible sustain."

Anyway, my pics were too big. I had to reduce rest;ution and post them one at a time.
Feel free to laugh at my work. I did some of this soldering 20 years ago.

[Professor3]

The Jacks

[Professor3]

The Preamp

[Professor3]

The Preamp and PI (with mods visible) The mods happen post controls. Thanks again for looking y'all. I'm afraid Sluckey was right and I'm going to have to call my brother and talk to him about how I remember these amps working.

[Pietro]

Hi Professor ,

Just became a member and had to respond. Just finished my own build 5e3. My findings are the same as yours. ALso expected more interactiveness.
Hardly any present. But i have nothing to compare it with.

I,m wondering if your volume controls pots are fine? Not scratchy and responding well ?

I took your picture because at least a couple connections are (at least to the eye) problematic for durabilitys sake. Especially the lead flying off number 1 seems barely attached.
It prolly wont be the cause of your problem though.

Use a knife to scrape the eyelet clean or use a dremmeltool before a new solder attempt.

Curious myself.

grtzz

[dude]

Whether or not your board soldering is causing your issues..?, I'd re-flow some of those joints on the board. Use a solder sucker and get old solder out best you can. Heat the eyelets with leads in just enough to melt the solder when the solder is close but not touching the solder tip, if it doesn't flow fast, like 3 to 5 seconds move the solder to touch the tip. Solder should flow, as you hold the tip to eyelet. Looks like you let the joints get too hot. You want a shinny bulb to cover the eyelet, like on you pots. 

[Professor3]

Pots aren't scratchy at all. I have re-flowed every almost every connection on the board. Some of the ones mentioned were ones where only so much solder would stick to the eyelet. I was worried about that too. Sometimes it seems like much of the solder just runs down the hole of the eyelet. I didn't want to get into a situation where connections are shorting under the board. Should I be using flux? Is it likely that I have to iron too hot? I usually run the temp pretty low for Guitar work or printed circuit boards, but I had it pretty much cranked for this. I have a lot of experience wiring guitars, but the best method for eyelets seems to be eluding me. I know some of the connections don't look pretty, but I don't think that's my problem. I'm pretty certain that the connections are solid. The amp is tight and noise free. I will re-flow them next week. Although the interactive controls are not as I remember them working, they do interact exactly as they do on several YouTube videos I've watched recently. Everything on the amp is working, and it sounds great. I'm playing my first gig on it in a couple hours. (I am bringing a backup)

[sluckey]

Some of the ones mentioned were ones where only so much solder would stick to the eyelet. I was worried about that too. Sometimes it seems like much of the solder just runs down the hole of the eyelet. I didn't want to get into a situation where connections are shorting under the board. Should I be using flux?

ABSOLUTELY! If those eyelets look like that on the top, you can bet they look like that on the bottom too. Very poor solder connection. Some look like you may have even used acid core solder.

All eyelets should be wire-brushed before soldering. But 20 year old eyelets will have a lot of oxidation that prevents solder from flowing properly. They need a little extra attention. This also applies to any old Fender amp.

Use a small wire brush to shine those eyelets as best you can. I have one that resembles a toothbrush and works very well for this. Then put flux on them. Use 60-40 or 63-37 lead/tin rosin core solder and a CLEAN soldering tip. Feed the solder to the eyelet until it flows smoothly and fills the eyelet. Then back off and wait for it to cool before touching the board. Repeat for every eyelet. When the entire board is done, clean it up with mineral spirits, then denatured alcohol. This may take 30 minutes for a standard 5E3 board.

[Professor3]

Got it! And I promise, I did not use acid core solder anywhere. I didn't think about the fact that these eyelets have been sitting for 20 years. I had to clean the jacks. I should have thought about cleaning the eyelets too. Some of them actually looked better BEFORE I re-flowed them. As my kids say, My bad. Thanks for the advice.

[Professor3]

Well, after the embarrassment of realizing how bad my soldering on the eyelets looked, I re-soldered a couple of the ugliest ones and took the amp out on a gig. I am really embarrassed by how bad the soldering looked. I should have realized why the eyelets weren't taking solder as expected. I think I was in such a hurry to have y'all look at the wiring that I focused my time on those connections and didn't pay much attention to the eyelets. Going to the shop tomorrow to reflow the entire preamp. The amp performed flawlessly last night. I have added the pre PI master volume and switchable negative feedback mod for Rob Robinette's site. Really great sound at a reasonable volume. This particular gig calls for mostly clean tones with overdrive supplied by a couple of pedals when needed. I know I have to fix the eyelet connections, but the darn thing sounded so good that my wife commented on how good my tone was. That's unprecedented. I know it's not like I designed the thing, but there is a certain satisfaction that comes with playing a guitar you built through an amp you built and having great tone.
 

[labb]

Old saying:   If it ain't broke, don't fix it.

[Professor3]

Okay, I think this is my last post on this topic. I will have one unrelated question at the end, but I wanted to kind of close out this chapter. I took the advice of Sluckey and Dude and others and completely re-worked the whole from end of the amp and some of the power section as well. I removed parts from the board a few at a time and used a solder sucker to clean out every eyelet as I worked. I cleaned the eyelets, scraping some with an exact knife where needed and polishing each one as I worked with some of the scotchbrite that we use for fret work. I didn't have a brass brush handy Steve, but I polished each eyelet till it was shiny and clean. I re-soldered each connection with a clean iron, making sure that the hole in the eyelet was full and the connection looked good. and being careful of cold solder joints. If a connection looked dull, I redid it and made sure to let it cool before I moved anything. I replaced the Xicon coupling caps with Orange drops. It took me a little longer than the 30 minutes Steve estimated, (okay, it took me a lot longer) but I was being exceedingly careful to do a clean job. When I was done, I took my layout picture and used it to check my connections using a different color marker this time. Then I plugged it in and checked to make sure it was working. I just ran it through its paces for about 30 minutes and it's tight, quiet, and I'm ecstatic about the way it sounds. The controls are interactive, just not the way I remember them. (I'm going to be talking to my brother Steve) Anyway, Thanks to all of you for the advice and thanks for calling me out on my sloppy workmanship. I'm embarrassed that I was about to let it slide. Regarding the "If it ain't broke, don't fix it" comment. I would agree with that 90% of the time, but I would really regret it if one of those funky solder joints came loose in the middle of a gig. Now my non related question. Should the chassis be pretty warm to the touch on the side of the power tubes? I'm currently running a GZ34 rectifier because a local amp guy told me the higher voltage would give me more headroom. I don't want to cook anything now that I'm happy with it. I do have a 5y3 as well if that would run it cooler.

[sluckey]

Should the chassis be pretty warm to the touch on the side of the power tubes?

yes

[vampwizzard]

If the power tubes are biased correctly and nothing is melting/smoking, im usually ok with warm (very warm) temps on a chassis. Also, for a 5E3, you can find some ballpark average voltages throughout the circuit/chassis to cross reference.

As for being embarrassed by your solder joints.. 99.9% of people who play guitar will never take the initiative to make their own tools. Its not like you had a master watching over your shoulder to give you advice or make a correction early on. Now that you know, you know. Either it happens on day one of learning to solder or day 1000.. doesnt matter.

What does matter is that youve gone through and made an amp youre happy with and performs as expected. Hopefully it makes joyful noises for a long time to come. Loved following this thread. Great work.