trinityamps.com

I got one coat of stain over the weekend. Used Dark Walnut Minwax. Ended up being a little darker than I thought but I like it. Just needs a bit of touch up sanding and then a couple of coats of finish.

Speaker showed up today

Found a bit of spare time this weekend to solder up a few more connections. It's starting to get pretty tight in there with the board in! Should just be flying leads left now.

Got the wiring finished this weekend. How does everything look? Sorry I don't have a proper camera to take better pictures. Just need to check point-to-point to the schematic and then I'll build a quick light bulb limiter for first power. Can't wait to hear what it sounds like!

Dumb question, how do you know what position you're in (4,8,16) on the impedance selector switch? I’m counting six different positions when I click it around.

I think my kit must have been missing that tang washer that was described in the manual to limit it to three positions. I'm assuming it's not critical as long as you don't turn it past the 3 settings. I read elsewhere on the forum that these Lorlin 2P, 6POS switches work as follows:

Lug 1 = yellow = 4 ohm = full counter-clockwise
Lug 2 = green = 8 ohm = one click clockwise
Lug 3 = orange = 16 ohm = two clicks clockwise

Can anyone confirm if this will work? Is there a way to test this? If I am in the 4 ohm position should I be reading 4 ohms between lug A and lug 1? Thanks

Your build looks really good! Very clean and neat.

Yes, it sounds like you are missing the tang washer that sets the stop on the switch.

You won't read 4 ohms between lug 1 and lug A of the switch. With nothing connected to the output jack you should read open circuit between lug A and all other lugs except the one the switch is set to connect. In that position you should read 0 ohms.

To put it another way, when the switch is set to "4 Ohms" you should read 0 ohms between the yellow wire from the OT and the hot (tip) terminal on the output jack. When the switch is set to "8 Ohms" you should read 0 ohms between the green wire from the OT and the hot terminal on the output jack. And when the switch is set to "16 Ohms" you should read 0 ohms between the orange wire from the OT and the hot terminal on the output jack.

Another way to check is to measure the resistance across the the output jack (hot terminal to ground) with the amp off and no speaker connected, of course. These readings will be really low, around 1 ohm or less, since you are just measuring the DC resistance of the secondary winding on the OT. The lowest reading will be when the switch is set for 4 ohms and the highest will be when it's set for 16 ohms.

You should try to get the tang washer or rig something up so the switch can't go to any unconnected setting. In that case there will be no load on the OT and that's very bad!

Thanks for the quick response Mitch, that makes perfect sense. Great explanation! Yeah I'll have to make sure I don't switch it to the open positions. I might just set it to the 8 ohms and then remove the knob to prevent anyone (my kids) messing with it. Although there's a lot more to be worried about if they're poking their hands around in there when it's on!!

Another thing you could do is just run short jumpers from lugs 1, 2 and 3 to the three unused lugs. These are probably 4, 5 and 6. You could check that with an ohm meter. Just find the lugs that read 0 ohms to the hot terminal on the output jack in the unused positions. That way the 4, 8 and 16 ohm sequence would just repeat on the other three positions.

An output impedance mismatch won't hurt the amp. You just won't get optimum signal transfer. In some cases that even sounds better! Having no load on the OT will damage it, though.

That's a great idea. Thanks!

Fired everything up over the weekend. It worked as anticipated with the light bulb limiter (went bright at first and then dimmed). Plugged it straight in the wall and got the following voltages with no tubes or speaker:

Line = 120.7V AC
Tx Secondary = 325V + 325V AC to gnd
Tube Heater = 3.52V + 3.52V AC to gnd
VRM @ idle = 443V DC at first 50uF cap

I then plugged the tubes and speaker in, set the B+ voltage to 400V DC and got the following:

Tube Heater = 3.45V + 3.45V AC to gnd
V2 Pin8 = 28.5V DC
B+3 = 330V DC
V1 Pin6 = 181V DC
V1 Pin1 = 188V DC
V1 Pin3 = 1.7V DC
V1 Pin8 = 1.65V DC

Took a little bit of knob twisting to finally coax a grunt out of the speaker, but it sounds amazing already even without the cabinet! Definitely a lot of different tones available with all the different controls. Are those higher heater voltages anything to be concerned about?

Glad the amp is working and sounding good. The heater voltage is about 9% high which is OK but it's not advisable for it to get much higher. That shortens the tube life.

Two coats of wax applied last night. I think one more quick sand with 400 grit and a final light coat of wax and that will be it.

It's looking great, congrats on the chassis build, the cab looks really good, nice workshop there too!

Xmas came a bit early for this guy! Turned out a lot better than I thought it would. Sounds awesome. Thanks everyone for helping me out. Thanks Stephen for a great kit! I thoroughly enjoyed the whole process of building both the amp and cabinet. Can't wait to start another one!
Happy holidays everyone.
Barry

The tramp has developed a bit of an annoying noise. I can only really describe it as a rattle that sounds like metal vibrating on glass. It only seems to happen with lower notes like striking the low E-string. Does that sound like it might be a bad tube? I haven't tried the 6L6 in it yet, so I could try that and maybe grab another 12AX7 to test the preamp tube as well. I'm not really sure how to troubleshoot this?
Thanks
Barry

In the manual, there is a whole section on troubleshooting rattles in cabinets. Check it out. It could be a rattling tube but more likely a loose part . Yes, try another tube if you have one but you will probably need an assistant to help you track it down. He/she plays the note while you poke around the back. Could be room noise too!!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps