Upon request I made a drawing of the amp cradle. I hope you can read it.
PDF blueprint of the amp cradle <<— CLICK HERE 🙂
Installing the VRM module
This amp is a tone monster, very cool – but very loud.
If you have not used tube amps before I can tell you 18 watt is way loud for domestic use. If you have you know what I’m talking about.
I knew this when I ordered the kit so I optioned for a VRM module.
What it does is…well let me quote Trinity Amps description:
It is designed to reduce the power level of your amp while retaining the sound. Essentially, you get very close to the same sound at a lower volume.
So basically it will let me adjust the voltage on the B+ from maximum (what I had on B+ before installing the VRM minus a couple of volt) to about 66 volt. The result when B+ voltage decreases is that the amp gets a lower power level but you can still get tube distortion, only on lower volume.
Pretty darn good!
Ok, here it goes:
The VRM module comes with a very good documentation
I am replacing the power switch with this 1M potentiometer that has a switch in it, that makes it look like it was there from the very beginning
Precaution, check the capacitor voltage! The amp has been switched off for almost 20 hours and still 17 volt on the cap. Discharge you capacitors before diving into the amp
Removing the power switch
Soldering the VRM pcb
Another angle
Drilling the hole for the MOSFET
Hey, I get to braid again 🙂 This time with three parts
The VRM pcb and potentiometer installed
The MOSFET installed
Installation done, I am now running the amp with 66.2 volt on the B+, as low as I get
Voltages measured with all the tubes installed
Here are my readings. They are a bit off from the specifications but this is a 220 volt version of the amp so that might perhaps have something to do with this.
The amp sounds amazing as far as I have been able to try it but I will of course check these measurements on the Trinity Amps forum just in case.
Here it goes:
That’s it for tonight.
The amp is far from done, I have a cabinet to build. Something tells me that is more work than this has been 🙂
Troubleshooting and finishing the amp
Ok, I made a mistake when I soldered the turret board. I have been very focused on all details and I have been progressing slowly and still I stumbled on this sloppy mistake. I hoped that I would manage to build it without any mistakes since I spent so much time going over every step on the way.
I wonder how difficult it would be to build a high gain amp, I mean like an SLO 100 clone or something in that territory. Hopefully I will find out some day.
Anyway, this is what I did wrong:
It might be an easy build but still – this is so easy to do, aargh!
It is supposed to look like this!
Ok, with that fixed I now had measurable plate voltage on all the tube sockets.
This is my measurements WITHOUT the tubes installed:
V1
Leg 1: 411 volt
Leg 6: 411 volt
V2
Leg1: 413 volt
Leg6: 416 volt
V3
Leg1: 413 volt
Leg6: 413 volt
V4
Leg7: 417 volt
V5
Leg7: 416 volt
I know these values are of no real significance until the tubes are installed but at least you need to know that there is voltage on the plates.
Let’s install the tubes!
Time to mount the tubes – yeah!
The preamps (12AX7) mounted, the protective covers will be installed later on. Lets enjoy the view a bit first 🙂
The two power tubes (EL84), the one to the far left is the rectifier (EZ81)
Look, it’s all there – this is so much fun!
This is it – let’s give it a try. Since I need to add a speaker (or other load) when I turn it on, I might as well plug in the guitar and try it before I do all the measurements.
FLICKING THE STANDBY SWITCH TO ON!
Behold the light 🙂
This is no ordinary glow, it’s plexi glow!
Looking good – no smoke and no humming from the transformers.
TURNING UP THE VOLUME…
WOHOO – it works!!!!
It works, and it works well!
First impressions are:
The amp is dead silent if I turn off the volume on the guitar and turn up the volume on the amp. If I turn up the gain to maximum I can hear a low humming sound but it is very low and probably as it should be.
The clean sound is surprisingly clean, I will do an A/B test with my Fender Deluxe Reverb. I mean this amp is a rock n’ roll workhorse, I figured I would get an amp where the clean sound would be modest. Quite a nice surprise 🙂
It is getting late so I could only crank it for a minute but if only you could see the smile on my face! 🙂
I’m getting a ZZ Top/Zeppelin sound. I can’t wait to really take it for a spin.
I made a quick check to make sure that all the potentiometers worked and that they were not reversed in the functionality – all was good. The boost switch worked as it should.
I can’t help feeling a bit proud of this. Except for a minor detail it worked perfectly. No hum, no hiss, no squeal – just pure rock ‘n roll sound!
Okay, lets put away the guitar and make all the measurements!
Voltages
After firing up the amp and checking the B+ voltage I did a quick check on the plate voltages and found that the V1 had no voltage at all on the plate.
I will check my wiring again to fix that, probably some minor thing. It may be one of the wires that I rerouted that is causing this.
Anyway, I will do more testing tomorrow and of course take photos of what I am doing.
If anyone is reading this and can give me some advice regarding what to check for, please do so 🙂
Overall feeling is fantastic!
This is by far the most exciting project I have done that involves a soldering iron.
Finishing the amp
Today I will solder the TMB and normal channel and then fire up the amp with the rectifier installed!
Working with the shielded cable from the TMB channel
The TMB channel soldered
Here comes the twin cable from the TMB channel
Insulation stripped, I will remove the shield and put on some heat shrink
Cable is ready for installation
Normal channel is up next, here are the jumpers between the lugs on the inputs
Cable is stripped and ready to be prepared
Done, ready for installation
Normal channel almost done
That’s it! Normal channel is done, all the wires are in place…
Rectifier EZ81 installed – this is it, will it work?
This is the first time I switch it on (really!)
No smoke! That’s good 🙂
This is a rectifier glowing in the dark (I couldn’t resist taking this geek shot)
Measuring the B+ , 420 voltage DC – good enough!
Today I fix my mistakes and wire the pots
Soldering the potentiometers was also a challenge, there is quite a few wires that goes here and there. I think it went ok, I have not had the time to measure everything yet.
Here it goes:
These are the two unused cable from the output transformer that should go OUTSIDE the chassi, not inside as I started out
This is the black shielded cable that goes from the gain potentiometer to the V2 (12AX7) tube, leg no. 2
This is the other end of the shielded cable, I have removed the shield and the insulation
I put on a short piece of heat shrink
Almost done 🙂
There we go, ready to be soldered
Here it is soldered on V2 leg no. 2
From the left: bass, middle, treble
Treble, gain , volume
Tone and volume
Tone and volume again, it is a tight fit for sure. The bright cap to the right was a bit tricky.
Gain and volume again
Aerial view of the wiring of the pots
Another one
Next up is the inputs, there a four shielded cables that I need to prepare and after that I will go through the amp and triple check everything.
After that there are some testing to do and if all goes well – perhaps some sweet plexi tone.
I have to fix two things
After getting some great feedback from Stephen at Trinity Amps I will fix two things:
First, those two unused wires on the output transformers that I cut and shrinked need to go on the outside of the chassi, not the inside as I have it now.
This was clearly mentioned in the instructions that came with the kit but I somehow managed to ignore that 🙂
Wires heat shrinked and tucked away
Second, those wires that I was a bit unsure about wether they would have to be short or neat actually had a third option, “not routed together”.
So I am going to fix that so that don’t lay beside each other.
Will the wires cause any humming?
Some serious soldering
I’ll have to be honest, this last part was a bit more challenging than I thought it would be. Since I am not in a hurry it is not a problem, I just take my time and resolder again and again if I am not happy with the result.
I will not under any circumstances have any bad solders in this amp. My goal is to get an amp that I know have carefully soldered joints and I have inspected every single one so far. And I intend to do so until it is done.
Having said that, I think todays work was very interesting and very demanding.
I know that I would have been more or less forced to take a break if I have not been using my Weller soldering station. It is simply fantastic to work with! 80 watt helps a lot when working on larger lugs like the ones on the impedance switch.
Here are some pictures.
I will post closeups on every part of the amp in the end of this build log.
V1 (12AX7), four 68k resistors, it is starting to get crowded
Fiddling with the resistor on V2
The resistor on V2 is done. You can see some melted insulation on the heater wires. Clothed wire is way easier to deal with 🙂
Some soldering on V3
Twisted wires goes to the boost switch
Routing wires, I have no idea if neat is better than short
Will the wires cause any humming?
Another shot of the wiring
One side is nearly done, the impedance switch is done
Allright, more work to be done tomorrow or on sunday.
I have to build a woodshed and things are starting to get wet outside so I think I have to prioritize that tomorrow.
Mounting hardware and turret board
I am finally finished with wiring the turret board and I am ready to mount it in the chassi and also to finish up the hardware pieces.
Here are some pictures from tonight.
Turret board ready to be mounted
Back of turret board, for reference
Mounting the last hardware pieces
Turret board mounted and never to be removed again – hopefully
It is close to finished now, I just have solder the wires and then the testing begins
The build continues tomorrow.
Handwired 