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Hi all,

First forum post, had my tramp kit unfinished since maybe september last year, board was built, some chassis wiring completed.

Anyhow last night and today I decided to get it done so finished wiring her up today.

Switched on, all good, first filter cap showing 420v. Ac at 630v and filaments getting 6.3v. All good so far!

Attached a speaker and dropped the tubes in. Powered on, 30 seconds later I'm getting a loud hum/buzz in the speakers. Tubes are fine. The voltage at first filter cap is 385v and remains there when I turn up. I'm guessing I've damaged the mosfet. I'll recheck all connections tomorrow.

I have a spare mosfet here from a vari watt kit originally destined for my 5E3, this is the datasheet.

Specs are slightly different to the one in the Tramp BOM, higher voltage and amps rating. I'm guessing it'll work but would love someone to confirm this part'll be ok before I drop it in.

Any ideas from the technical minds here much appreciated!

Jim

Ok, so I had stupidly conncted the power grounds to the 6.3v connector tab, hence the hum.

I swapped out the mosfet to the one mentioned above, now I have voltage movement on the VRM between 403v and 407v. Pretty subtle but at least I know the circuit is working!

I think the replacement mosfet is out of spec for this particular power scaling type application though so I'm going to order up a new part that fits the specs in the BOM and hopefully have a better range of voltages.

In the brief minutes I had to listen to the amp is sounds great! Thanks Stephen for putting together such an excellent circuit and kit!

I'll post back when I get the right spec mosfet.

Cheers all!

Ok, got the replacement mosfet in the Tramp and...

I get a range of 4v between 388 and 392v at the first filter cap. VRM ain't working.

I'll triple check wiring around the mosfet and check component values etc.

Any help as to what could be wrong would be much appreciated!

Cheers

Jim

Sooooo, it seems the culprit may be the power level pot.

It measures out at 894R instead of 1M. This would account for the low voltage swing with the travel of the pot would it not?

894 ohms really is too low!

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Great tones come in small glass jars!

Did you take the pot out an measure it out of the circuit?

I guess 1K and 1M could get mixed up...

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http://pdfelectronics.com

I'll pull it out of circuit to measure it properly tomorrow and post back, thanks for the replys guys.

If it's our Alpha switched pot, it should be labelled 1MA (1 meg audio) take it out & measure it across the 2 outside lugs. If it's 1K, we'll send out the correct one.

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

It's the one that came with the kit, out of circuit it measure 901r. It's not labelled.

I think this may be the problem!

1K won't be much help in there. Will get you a 1M

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

Great thanks!

New volume pot in and problem solved, I now have the VRM working and it's all good, thanks to Stephen for sending the right pot and thanks to you guys who helped out with your posts.

I'll post a pic when I get the cab later in the week

Ok, here's a pic of my lovely blonde tramp head with matching 1x12 cab. Currently loaded up with a Genelex Gold Lion KT66 and an old stock Mullard 12AX7. Speaker is a Celestion blue.


Very happy builder here, sounds great.

Cheers to Phil and Stephen for designing such a great little amp.

Peace

Jim

Congratulations!

It is indeed a thing of beauty. I like the blond treatment.

Nice tube and speaker choice also.

Wow, that looks amazing!!!

I would love how to hear how it sounds with the tubes you've got in there!

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Great tones come in small glass jars!

Wow! Just like a bought one, only better. I'm also keen to hear how the tube and speaker combination are working. Did you fire it up with JJs (with the 6v6 power tube) to begin with, or just go straight for the fancy stuff?

Thanks all! Still to add piping and some corners when they come into stock, will post a pic when complete. Incidentally I should big up my cabinet builder here in the UK Rory Coupland, did a cracking job.

The Genelex KT66 is new production and sounds great, curious as to how much difference an old stock one would make...

Handlefras I did indeed try the jj's and frankly they sound sound great too. Different tone for sure with the 6V6, a little more aggresive/peaky in the midrange perhaps but a more than usable tone. Put it this way if I were stuck with only stock config JJ's in this amp I'd be happy. I went nuts and got one of each, SED winged C 6L6GT, Svetlana EL34, Gold Lion KT66 and Tungsol 6V6 (already in the 5E3)

The 'trad' 12AX7 and 6V6 combo with the Mullard and the Tungsol sound a little more refined, more clarity and note definition perhaps than the JJ's but with a great deal of grunt when pushed. (Apologies for the less than poetic use of language but I hope it helps paint a picture)

Having an array of sounds so tweakable with one power tube change, not to mention the tonal variation within the controls of the amp itself give a dazzling variety of sounds.

The blue is a great speaker for this little fellow. I must say I've not treid a 1X10 speaker so can offer not comparison here. Up until a week ago I was using a closed back 1x12 Marshall cab with a G12H30 in. Once again it sounded good in this context but I reckon I've hit the big time with a semi open back, fixed baffle cab with the blue. Seems to sit very well with the amp.

I have to add to previous comments about how this little amp likes pedals too. Sounds simply awesome with a bit of boost (and a lot!) I have both a KOT clone and a Madbean Fatpants (which is rarely switched off with any amp) and they both push the Tramp into a most wonderful mid gain overdrive. Hard to believe it's two tubes!

Phil, I'll try and get a few clips recorded over the next few weeks and figure out how to post 'em here.

FYI clips would need to be hosted somewhere like Soundclick or Soundcloud. Then you just post the links to this site.

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Great tones come in small glass jars!