5E9 Tweed Tremolux Build Thread: Pics on Page 11

[Racing]

Recheck integrity of circuit for the trem tube.
In turn,the trem tube is a regular 12AX7 aka ECC-83. One of THE most common small signal triodes there is.

Anyways. Recheck the circuit for integrity. I wonder if you could have gone wrong and are sending DC voltage for the 220k tremolo resistors at the powertubes.?

[wproffitt]

Will do! In the meantime, have I done something stupid by NOT running a ground from the switch jack up to my ground bus?

[Racing]

Output?
In such a case no. As long as it sees reference. Ie;chassis ground. Then we´re all good.

[wproffitt]

It's the jack to the foot switch, if that's what you mean by output here. If so, I guess that's not the problem!

Thanks!

[sookwinder]

remember the quality of the 12AX7 for the trem is not really that important, it just needs not to be weak/used a lot previously

[wproffitt]

Rechecked my wiring to the tube sockets again tonight. Everything looks fine according to the layout. With fresh cheap tubes in V2 and V3, I turned the foot switch for the trem on and off and watched what happened:

1) Again, a hum was audible when the effect was turned on at the pedal (nothing happens a all when I use the switched "speed" pot to turn the effect on) .
2) Then, v4 glows a bit less bright and v5 begins to red plate.
3) at the same time, v2 glows a bit brighter, but no red plating.
4) after a couple of minutes of this, I shut it down, but things looked fine otherwise.

I tried pulling v3, which is associated with the trem. When I fired it up, the hum was instantly present, but when I clicked the trem foot switch, it went AWAY and the red plating on v5 started right up!

What am I missing?

[sookwinder]

Scott rather than using the pedal to initiate the trem, have you tried using a shorted Phono plug ( ... or is it an RCA plug ? I have no idea whether the 5E9 uses a RCA or Phono for the foot switcg plug in)

This way you can illuminate any thoughts of the pedal being the issue.

Just put in / then remove the phono to turn on and off the trem and watch what happens.

I have never actually seen a 9 pin preamp/trem/PI valve red plate .. if it gets brighter as far as I know that is just the valve working a bit harder. I would not worry about that.

[wproffitt]

Scott rather than using the pedal to initiate the trem, have you tried using a shorted Phono plug ( ... or is it an RCA plug ? I have no idea whether the 5E9 uses a RCA or Phono for the foot switcg plug in)

This way you can illuminate any thoughts of the pedal being the issue.

Just put in / then remove the phono to turn on and off the trem and watch what happens.

I have never actually seen a 9 pin preamp/trem/PI valve red plate .. if it gets brighter as far as I know that is just the valve working a bit harder. I would not worry about that.

I'll give it a whirl. How do short the phono plug (no RCA here)? Do I cut one end off of an instrument cable and solder the two wires together?

[sookwinder]

well yes you can cut a cable ...
alternately you can buy a phono plug on its own and short it out or even do you have one of those pedal connecting short cables if you do you can cut the end off and connect the wires or because those pedal cables are so short in length... just use one end tyo plug into the amp and then with the other end phono plug just wrap wire around the end so you are shorting out the two section of the plug at that end... the wrap some gaffer tape around it so it doesn't touch any other metal parts

[wproffitt]

See the turret below the tome pot with the junction of the two 1meg resistors and the 220k resistor? It didn't have continuity to ground. I FEEL like I did an under board wire when I wired this up originally, but for whatever reason, this wasn't working, so I jumpered the turret in question to the bus bar and guess what? No more red plating! I haven't been able to try the trem because the kids are sleeping. I'll report back tomorrow.

On an unrelated note, would an un-switched 2 meg pot work for the speed control in this amp? The used/surplus switched pot I have is not exactly smooth and I have nice in switched pots sitting around waiting to go in.

[sookwinder]

Scott ... great pickup up ... I hope this "turret problem" was the main culprit.

regarding the pot... yeah switch or no switch, it still should function correctly.

[wproffitt]

Thanks, David!
In all honesty, I can't take credit for catching the grounding issue. Someone on another forum who happened to have owned a 1955 tremolux caught it.

I got to spend some playing through the amp this afternoon and noticed a few things:
1) it sounds great! The harmonics are rich and the sound, especially through the bright channel, is full with some guts.
2) there is an odd noise on the second input of the second (normal) channel. It's kind of like a low grade, chattering noise. It doesn't happen on the other inputs, so that's good. What's up with that?
3) still no red plating!
4) the trem still doesn't work. I didn't think the grounding would be the magic bullet, but I did keep my fingers crossed. Should I check the pots associated with this part of the circuit or is there some other place to start while trouble shooting a tremolo?

EDIT: I'll start with a shorted cable for the trem switch and see what that reveals.

[wproffitt]

I just took some time to work on the noise on the second channel and its volume pot and it turns out it was not grounding but the position of the signal wires going into V1. Now it's dead quiet. Hooray!

I changed out the Speed pot and that did NOT make the trem come to life. The motion of the potentiometer is much more smooth now, though!

I tried a shorted cable in the trem jack to get it to turn on, but no dice.

It's got to be a wiring problem, but where? I'll be checking my connections again later today, if time permits.

Edit: I took it to rehearsal today and it sounded great! Definitely louder than my PR and a totally different sound. It's cleaner than I had imagined it would be at rehearsal volume, but what a gorgeous clean! The mids are more full and the bass, while somewhat less tight than the PR, still has plenty of round oomph.

[wproffitt]

Thanks for the help! It's working!
Earlier tonight, I rewired the speed pot to work as a regular, non-switched pot to simplify the situation a bit, but to no avail. Then, I checked the voltages on V3 and not one, but a few of them were WAY off, so I sat down in front of the amp and stared at it for a while. I thought that either I had made several wiring errors all coming off of the same tube OR there was something I wasn't seeing with the socket. Being lazy, I had a closer look at the socket and observed that one or two strands of braided wire were connecting pins 1 and 2. The same thing was happening between 5 and 6. I was only able to see this when I zoomed in with the camera on my phone. I broke these connections and tested my voltages again. Things looked good. I then turned the amp on and pushed the foot switch and heard an oscillation. I plugged in my guitar and there was the beautiful sound of the bias vary trem!
I can't thank you all enough for your time and wisdom in this project. I wouldn't have been able to complete this without people to point me in the right direction. David and Racing, you helped me get this across the finish line I'm very happy with the results! I've got a rehearsal this week where I need the trem effect, so the timing could not be better.
Vanity pictures and clips to come in the next few weeks!

[Racing]

All to glad to help.

Good to hear you figured the trem out. Many a time older trems can be to fast in operation even on their lowest setting. This can be modified,normally by altering the capacitances involved for the tremolo tube. You simply "go bigger" need be.