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Hi all,

I've got my Tramp all put together (thanks mostly to Steven's excellent support ). It's my first build, and I've made a few mistakes in the process, so I would appreciate any feedback from those of you with more experience. I ended up replacing the MOSFET and its associated resistors because I fried the first one de-soldering. I was an idiot and soldered it before placing the board, so of course it didn't line up. The replacement resistors are exactly the same spec as the originals, just wire wound FYI. I should also note that I'm using a Tone Tubby Humboldt 10" 8ohm as the speaker and a JJ 6v6 as the power tube. Here are some pics:




Before I get into the issues, here are some voltage readings (tweed/thin):

AC
Heater voltage is @ 7.0V

Power Amp
B+ is 430V. The VRM was set to 400V for all measurements
Cathode Voltage is 28.8V

Pre Amp
R8/C6 is 340V
V1 pin 1 is 173V, pin 6 is 168V. With the VRM cranked the Voltages are roughly 180V and 170V respectively.

The bias switch is set to 6v6 and the impedance selector is at 8ohms.

So the issue I'm having is with the amp's volume and gain output. All of the tone controls, as well as the push pull functions seem to work, but there just doesn't seem to be much output. With a single coil strat (volume all the way up) and everything on the amp cranked, there is no breakup and it isn't really as loud as I would expect. It also sounds uncharacteristically thin, with very little bass even from the neck pickup. With very hot humbuckers, I can get a little bit of breakup going with the volume past 8, but it sounds raspy and thin. It's pretty obvious that this is not normal, and that the amp is capable of MUCH more.

Steven suggested that this could be an issue with the tubes, so I decided to order a Tung-Sol 6L6 and 12ax7 as well as a JJ EL-34 to play around with. If anybody has any other ideas or suggestions in the meantime however, I'd love to hear them!

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One thing for sure, your mains is pretty high out there. I'm guessing 125?
Is the 1M beside the .1uf input cap, grounded?

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

It measures at 123V on my meter, so great guess. And yes, the resistor is definitely grounded.

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wondering if you tried it with a different speaker

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

I took the speaker out of a Fender Mustang II today (12", 8ohm, 75W I believe) and there was a bit more bass response. The volume was a lot better, and the longer I played, the warmer the tone got.

The biggest thing I've noticed is the tone sounds fantastic on the top five strings on all my guitars. Creamy warm and full of tone! But notes from the low E string noticeably drop off in volume. The lower the note, the thinner it sounds. It's almost like something is cutting out the low frequencies.

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Congrats on your Tramp build.

When trying the different speakers, you mention, "I took the speaker out of a Fender Mustang II today (12", 8ohm, 75W I believe)" for comparison to the 10" Tone Tubby, what speaker cabinet(s) are you using in comparing and evaluating the volume and tone of the speakers and the amp? I mention this because speaker cabinet size and design can play a huge role in the Bass response achieved, as well as the overall apparent volume. I guess my question here is, at this point in your testing do you have the speakers installed in a cabinet?

Great news everyone! The new tubes arrived today and fixed the issues I was having. I took both of the JJ tubes out and put in the Tung-Sol 6l6 and 12ax7, set the Bias switch to 6l6 and suddenly I have bass and volume galore! I was starting to think that I had just misjudged the amp, and that it was supposed to sound a bit thin, but man is the difference night and day with the new tubes installed. The amp now sounds full even without the fat switch on, and with it pulled it just makes it even better. I don't know whether the culprit was the output or pre-amp tube since I just swapped them both out at the same time, but I do plan on figuring out which one was to blame later on.

To answer the previous response, I was testing the speakers just sitting on my bench. I know a cabinet will affect the amount of bass produced, but the problem wasn't so much low bass output, it was more like no bass output. I didn't think adding a cabinet to the mix would really make a huge difference.

I re-measured the voltages with the new tubes installed, and here are the results:

Voltage on both filter caps decreased to 402v and 395v

Voltage at the 6l6 bias resistor is 26v

V1 and V6 voltages on the preamp tube are 176v/174v in tweed mode.

I did have some squealing with the volume on 10/10 on both knobs, but it's too early to annoy my neighbors testing it further. I'll do some more playing on it later today to see if I can figure out what the issue is.
Thanks for the responses, and another huge shoutout to Stephen for helping me get this far. I'll definitely be looking at some of your other kits in the future

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Glad to hear you got it sorted and it was as simple as the tubes, it's nice with a good 6V6 but the amp definitely hits it's stride with a good 6L6GC. I think you will love the Tramp and once you get the speaker into a good cab you'll be amazed how nice the amp sounds and it's such a good feeling to know you built it.

Speaking of cabs, I'd love to try one of Trinity's "Sidewinder" cabs with my Tramp Head, love the idea of the closed back and the side ports for spread.