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Pretty sweet. The plexi ideal is kinda cool.

I like to shield the bottom (back in this case) of the chassis to help cut down on RF interference & whatnot. Any issues with that when it's close to other electronic devices?

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SG + Brit tube head = Nirvana

Up until now I didn't have issues without the shield. I must try to test it like you suggest.

Keep you posted about that soon.

Cool, Try the KT on 6L6 setting. We'll work out the ideal cathode value but you are OK with that for now. Remeasue & see how it works out.

What cabinet size did you end up with in the end. Looks pretty small.

And most importantly, how does it sound?

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

I wonder where this 70% of anode current rule comes from, as I've never heard of it before. I wonder if you mean the 70% of max *dissipation* guideline for Class AB amps. As this is pretty much a true Class A amplifier, we bias the power tube to around 100% of maximum dissipation.

To calculate the power dissipation, work out the screen grid current (using the voltage across the 1k screen resistor) and subtract that from the cathode current. That will give you anode current. Multiply that by the difference between the anode and cathode voltage, and you will have the actual power dissipation of the tube.

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Great tones come in small glass jars!

The cabinet is pretty small at 15.5" wide by 14 high. The depth at the top is 7.5" and 9.5" at the bottom. It is the smallest I can make it to accomodate the big Transformer and that particular Speaker. If I want to try another speaker I will have to connect a cabinet or else buy another Tramp kit. By the way, do you know if we can remove the Bell cover on the Jensen Blackbird Speaker?

As far as I can tell, the sound is fantastic. I really like it. I tried the Tramp with a Strat and a Les Paul and so far I've got plenty of different sound. For an amp with only one preamp tube it got very good distortion and the tweed tone is fantastic with the Strat. Thank's guys for working out a super sounding little amp. Great for practicing at home and more than loud enough.

Will Try the 6L6 setting and return to you with the readings.

Thank's

Here is a pic for size comparison, the Tramp and my 18 Watts V6 with 2 speaker cab.

For the 70%, I think I took it here. http://www.aikenamps.com/Why70percent.html

But I may have mixed some things. I'm no Zaphod I think it is time to reread this text

Thank for helping me understand.

Yes, that is referring to the percentage of maximum dissipation in a Class AB push-pull amp. Here we have a single-ended Class A amp.

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Great tones come in small glass jars!

Thank you

I put the switch in the 6L6 mode at full VRM and I got a reading of 28.9 Volts across the cathode resistors (318R). That give me .0909A for the cathode current. I got 2.5 volts across the 1K screen resistor which give .0025A. If I subtract this from the cathode current I get .0884A for the anode current. The voltage between the cathode and the plate is 342 volts so if I multiply that by the anode current .0884A that gives me 30 watts ???

Something must be wrong in my reading or in my calculations.

Nice work on those amps, they look sweet

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Fantasy Noise is what my shop of dreams is called and was the only way to beat my addiction, like many here I suffer from G.A.S.


Tele's make the best noise

30 watts for a 6L6 is correct!

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

6L6GC that is....the prefixes actually matter with 6L6s tubes. The 6L6 is rated for something like 20W iirc.

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http://pdfelectronics.com

Right you are. 30W bang on with a JJ 6L6GC

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

But the reading i got is for a KT66

The tramp isn't supposed to be a 10 watts amps with that type of tube ?

Hi,

I was occupied recently but by checking the Tramp forum, I found that nobody had answered my last question. Holiday, holiday !

1 So i retry it. My previous measurement and calculation give me around 30 watts for a KT66 based TRAMP. Is it normal or do I goof somewhere ?

2 The Tramp isn't supposed to give only 10 watts with that kind of tube ?

Thanks,

It would be good to know, just for reference, the B+ with the KT66.

Based on my calculator, for the numbers you provided, this is a dissipation of 27.5 watts. You could increase that if you wanted to by changing the cathode resistor in this position.

What the tube dissipates as biased & what it delivers to a speaker load are different. Ideally you need to measure the output into an 8 ohm load and calculate the power.

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

Wall is 117.5 ACV

B+ is 435 DCV

If I understand correctly I just have to take the voltage on the speaker as I play and using P=(V*V)/Z I can get the power. Z being 8 ohms.

Thanks Stephen.

You need to increase the value of the power tube's cathode resistor for the KT66 then. It should not be dissipating more than 25W. So far we never said it was safe to run a KT66 on the 6L6 setting.

The maximum power output calculation is a different matter. In a true Class A amplifier, it is slightly under half of the power dissipation. So for a KT66 or EL34, the theoretical maximum power output is around 12W. With a 6L6GC dissipating 30W, it's around 14W output.

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Great tones come in small glass jars!

Thank's Zaphod

Is there an easy way to find the correct value for the cathode resistor or do I have to try different values until I get the correct plate current ?

Until I find the correct value I think it is better to use the 6v6 cathode resistor even if the KT66 run a little colder or simply use the 6V6 tube to not harm the pricier KT66 Tube.

It's basically trial and error method. Since you're not far off, if your at 27.5W, I would guess that increasing R15 to 620 ohms (parallel with 750 ohms -> 339 ohms) would probably get you about there. Running a KT66 on the 6V6 setting problem wouldn't sound very good, as the KT66 would be biased extremely cold.

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Great tones come in small glass jars!

Runninng on 6L6 setting, I think Serge has a dissipation of 27.5 watts.

We've listend to my Genelex KT66 in this position and it has nice, big, full, sound to it.

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