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Thank you for the info Zaphod.

If someone want the logo, I can post the Jpeg I used to cut it out.

Here is the completed amp. If you can spot error on the wiring, let me know. I triple checked the isolation between the MOSFET and the chassis and it is OK.

By the way, can you show me how to post small picture that we can click on it to have a bigger picture. This thread would be cleaner and more effective that way. Like the thread of Stephen for his first production build. This is very clean. Thank's

Looks good with a quick glance. Good idea to double check.

At the bottom of the window, when editing a post, or posting a new one, you'll seee " Upload attachment" , to attach one or more files enter the details as requested (browse , Add the file , etc.).

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

You might consider braiding the wires going to the VRM control pot.

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That's a good point. I always do that. But try it without and see if it's quiet when you change the voltage. If not, twist the VRM wires around each other going to the control pot.

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

I tried it without braiding the wire and it is quiet even when I turn up the VRM level.

Hehe, Guess what?

Remember the copper shield i installed over the heater wires... It caused me a problem. When I first started the amp for three seconds I smelled an odor I didn't like so I shut the amp immediately. I suspected the resistor for the LED because the smell seemed to come from that spot. Eventually I found the culprit. A tiny bit of the copper shield touched one lug of the terminal strip where are connected the wires for the LED. Fortunately, the PT survived. Good lesson for me.

I am still waiting for the Tolex and the speaker grill I ordered from Tubes and more. I temporarily installed the speakers and the amp in the cab to try it out. Now I'm in the process of exercising the speakers with a 6 volts Transfo because they are stiff.

Don't expect great description for the sound because I'm not an accomplish musician like all of you. I just know a handfull of chords.

Short side story: In my quest to find some Tolex locally, I went to a textile merchant who happened to have plenty of Tolex on display. After 30 minutes or so browsing, I found a rather interresting one. A kind of textured snake skin. So I asked the merchant the price of that particular Tolex. He turned the sample looking for the price tag and told me it is 131$ per yard. I ended up ordering my snake skin Tolex at Tubes and more at 12.95$ per yard.

Here is what the amp looks like for the moment. (Thank's Stephen for the hint. Attachment works and it is much cleaner that way.)

Is the Traamp up and running You didnt actually say.

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

Hehe !

Yes the Tramp is Alive and kicking. ROCK & ROLL he says.

Great sound. I think I'm a 'Tude kind of guy . Normal you say for someone who knows only a handful of chords.

Didn't have time to test it more but like I said earlier, right now I'm exercising the speakers so they will be more... fluid... or less stiff. But the sound is already great nonetheless. Sorry I'm not a sound poet. Can't elaborate more. But Great Job Stephen and Zaphod for the design and all the guys who have given their opinion to improve the Amp.

As a bonus, the thing is much more portable than my Peavey Classic 30. As another bonus when the time come to change the tubes it will not cost a bundle to do so.

By the way can someone tell me if a kt66 will be much powerfull than a 6L6 or just more Marshallesque?

Here is a picture of the back with the temporary flying wire connected to the speakers. There is a 2 inches 'distance' between the magnet and the 6V6. I Was forced to install the 10" on that side because the 8" on the other side didn't like the big PT installed. In fact there is only 1 inch between the PT and the speaker baffle board.

I Like it, I like it !

The KT66 may be a tiny bit louder than the 6L6 but not by much, negligible I'd say. It has a very different tone though.

Nice looking amp there.

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In 'Tude mode:
6L6 - Fender Bassman-ish
KT66 - JTM45-ish
EL34 - Plexi-ish

For KT66 operation you will probably need to change the cathode resistor value to get the tube biased correctly.
An EL34 should work OK with the same cathode bias resistor as for 6L6s, but you should change the OT primary tapping for 2500 ohms instead of 5k.

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Great tones come in small glass jars!

We didn't measure the bias when we plugged in the KT66 so next opportunity we will and see where we stand. We can report that it did sound good.

For the EL34, it would be best to add another switch in the spare hole in the back, to allow switching to EL34 OT impedance (2.5K). We also need to confirm the EL34 wiring.

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

Cool. I'll be wanting to know as I plan to have a KT-66 mode. In fact, I'm toying with the idea of a rotary switch with 6V6/6L6/KT-66 modes. You know me - I just can't leave things TOTALLY stock.

Adding the switch for the EL-34 OT impedance opens up yet another tonal option - the KT-77. Less compressed than a EL-34 but more than a 6L6, less bouncy than a 6L6 but more than an EL-34. I have them in my 2204 & really dig it. The KT-77 biases pretty close to a EL-34 (in my 2204 anyway) so that shouldn't be a problem. I've never heard one in SE mode so I have no idea how it would react. I suspect somewhere between the 6L6 & EL34.

As a side note, I was listening to clips of one of Reeves newer designs yesterday. It's a 10w high gain job with 2 12A?7's (one AX & 1 AY I think) running SE with a single EL34. Nice. Nailed 80's metal. Gets me thinking about that additional pre-tube with switchable cascaded gain stage again.

Maybe this response should be in a separate "Potential Modifications" discussion thread!

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SG + Brit tube head = Nirvana

A rough rule of thumb is that true Class A amps will produce a maximum power output of just under 50% of the anode dissipation. 6L6GCs can be biased up to 30W, whereas KT66s and EL34s dissipate 25W maximum. KT77s have a 32W maximum. So you're probably talking of the difference between 12W and 14W at best, which is barely audible.


The stock Tramp design is good for EL34s (pin 1 grounded). I made sure of that.

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Great tones come in small glass jars!

LOL, No sooner do we intorduce an new and, than people are planning to mod! Exactly why we put the extra hole there.

Start a new thread for sure on this one!!

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

Have you guys tried an EL34 yet?

Joe G

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Some assembly required,
Brain sold separately...

Not yet, 6V6, 6L6, KT66 so far.

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

After further testing it appear that the Jensen C8R speaker didn't sound very good. In fact, i'm not even sure if this speaker is OK since the sound is so different than the 10". So I am rebuilding the cabinet right now so it will be very minimalist in term of dimensions. I am adapting it to the sole 10" Jensen C10Q. The dimension will be 15 1/2" wide by 14" high. The side will be 7 3/4" at the top and 9 1/2" at the bottom. A kind of mini Tramp. I am thinking of putting a 6L6 or a KT66 inside to have more power in a tiny amp. Anyone have installed a KT66 Yet ? IF so, could you tell me which resistor value to use to bias the tube correctly ?

Will post pictures of the new cabinet when done.

Hi !

I finally received my Tolex and finished my minimalist Tramp. See the picture posted. I put a plexi on the back so I can see the innards of the beast.

A little help is needed for the biasing of the KT66.

I measured 37.2 volt across the 735 ohms cathode resistor at full VRM. Am I correct assuming that (I = E /R) there is .0506A going through the cathode. If I read the JJ spec for the KT66, .085A seem to be the maximum plate current value. So the rule of 70% of the maximum plate current give .0595A for the cathode current. In comparison my .0506A give me 59.5%. This seem a little cold.

Is there a way to find the correct cathode resistor based solely on the above numbers. Thank you for correcting me and your help.

Where are you getting 725R from? When in 6L6 mode is the cathode resistor not effectively ~320R?

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I let the switch on the 6V6 mode so the 750 ohms is when measured 735 ohms. I was affraid that 320R wold be too little.

It is safe to use the 6L6 setting and probably much closer to what a KT66 ideally wants.

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