36 watt build

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Tfultz
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36 watt build

Post by Tfultz »

New 36 watt El34 build in progress. JTM 45 chassis. Using layout by jmpguitars. So far I have the chassis put together except for a 50k mid pot I must have forgotten to source out. GDS 36 watt trannies mounted. Had to drill out some bigger holes to mount parts. Tapped in turrets on board. So far so good.
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Re: 36 watt build

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Any advise or tricks or potential problems. Chime in. Thanks.
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JMPGuitars
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Re: 36 watt build

Post by JMPGuitars »

Very nice. I'm looking forward to hearing your demo when it's all done.

Here's a tip: pay close attention to your heater wiring. Try to compete with mine:
heater-wiring.jpg

Also review the solder technique videos linked from the soldering thread: viewtopic.php?f=4&t=25396

Even if you are experienced, it's a good refresher.

Thanks,
Josh
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Re: 36 watt build

Post by Tfultz »

I was looking at your pics jmpguitars. Do you jumper all 4 posts of the sleeve for effects loop?
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Re: 36 watt build

Post by JMPGuitars »

Tfultz wrote:
Sat 06/20/20 7:48 pm
I was looking at your pics jmpguitars. Do you jumper all 4 posts of the sleeve for effects loop?
Yup. And speaker outputs.

Thanks,
Josh
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Re: 36 watt build

Post by Tfultz »

She’s getting closer.
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Re: 36 watt build

Post by JMPGuitars »

Tfultz wrote:
Fri 06/26/20 7:12 pm
She’s getting closer.
Nice! Looks like you're off to a good start.

Now I'll be nitpicky. ;) A few things:

1. Cleanliness is everything. Keep the leads straight, and keep them away from anything they shouldn't be touching.

2. If a turret breaks, you can usually drill it out with a smaller drill bit to clear the hole and mount a new turret.

3. The V1 cathode caps: you'd be find with 16 to 100V. 630V is not needed, and harder to work with. Both of those cathodes will only be seeing around 1 volt.

4. Grounds: I can't see if the output jacks are grounded to the star ground, but they should be. It may not matter, but it might be better to have all of your power amp stuff sharing the same star ground point at the lug you have for the cap can ground, or possibly switch the cap can to the other one.

5. Heaters: look pretty good! But, once your sockets are wired, tuck the heater wires tighter to the socket, and have the heater wires as close together as possible all the way up to the socket (except the power tubes, they look pretty good, except that yellow wire hanging out?).

6. Soldering: I see some inconsistency, and can't see how good the mechanical connections are. Take a look at the Soldering Technique thread, and the linked videos to brush up a little bit.

7. Be careful with non-insulated leads like those on resistors and other components. It might be the camera angle, but it looks like the input grid resistors are resting on the purple heater wire. They shouldn't be touching at all. Personally I would add some heat shrink to the resistor leads.

Speaking of resistors, I don't see any on your input jacks? Are they hiding? The 1M input resistors should be metal film.

Thanks,
Josh
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Re: 36 watt build

Post by Bieworm »

I see you provided an FX loop. Good thinking! You're gonna need it when using delay or some digital effects. In the front they are pretty discouraging on my amps. But since I made the loops I love my amps more and more.
I'm building a stand alone reverb unit right now. And it will be built in an extension cab. So the 1x12 combo stacked upon the 2x10 cab with reverb. That will be an awesome stack right there!!! And very portable ;)
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Re: 36 watt build

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She’s built. Here are my voltages. Have some issues. She makes noise but is really really low. Master volume works but gain just makes it really bright until all the way up then gets lower. High mid and low controls do their thing but it’s so low volume. The 2nd output jack doesn’t work only the jack connected to impedance switch. Did some chopstick prodding. The shielded cables are my first thoughts with gain control and input not working properly. Any ideas?
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Re: 36 watt build

Post by JMPGuitars »

Step 1 is a highlighter test (with the amp off). Print the schematic AND layout. Verify every single component value and connection, only highlighting after verifying. Start at the input jacks.

Thanks,
Josh
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Re: 36 watt build

Post by Tfultz »

Are the voltages in range?
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Re: 36 watt build

Post by JMPGuitars »

Tfultz wrote:
Tue 06/30/20 7:58 pm
Are the voltages in range?
Some of them. You can see where they vary on the chart. But even with that level of variance I would expect more signal. My first guess is miswiring or a bad component (or bad value).

Thanks,
Josh
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Re: 36 watt build

Post by Tfultz »

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Re: 36 watt build

Post by Tfultz »

It was the inputs like I thought. I made my own shielded wire and redid some solder. She came to life. No squeals. Super quiet even with everything dimed. The el34’s are like a shot of steroids. Huge sounding. My next issue is the effects loop though. It doesn’t like any cables plugged into them. Earth shaking rumble. Any ideas on how to tackle that. I also need to re test the voltages but i’m assuming they are the same since it was only the jacks that were the issue.
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Re: 36 watt build

Post by Bieworm »

Did you ground the jacks of the fx loop? That was my problem at first... its not clear on the layout but they have to be grounded
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