Troubleshooting, Biasing, and Tone Testing - Mojotone 800 Build Part 6
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- čas přidán 22. 08. 2024
- Welcome to Part 6 of my Mojotone 800 build series! In this episode, I will be diving into the troubleshooting process, biasing the tubes, and testing the tone of the amp. Stay tuned as I walk you through each step and provide tips and insights along the way.
Tube Bias Calculator: robrobinette.c...
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If you're a fan of DIY amp building or just love to see the inner workings of these vintage gems, this video is for you. Don't miss out on learning how to troubleshoot issues, properly bias tubes, and achieve the perfect tone in your amp.
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Really enjoying your channel, thanks for all the info. I just ordered the Mojo 2204 JMP kit. Wish me luck…
Cool!! Just take your time an triple check everything. Here is a guide that can help you: tinyurl.com/28r2s5k3/ . It has good explanations for testing and troubleshooting and other useful information. Just use the wiring diagram that comes with your kit and use this guide to help you along the way. Let me know how it turns out. Good luck 🎸🤘
Will do. Thanks for the link!
Fantastic job. Looks clean inside, sounds great. I pulled the plug on a mojo tone GA5 amp kit after watching your videos. Thanks for the series.
Thank you so much for your kind words and support! I'm thrilled to hear that my series inspired you to get the Mojotone GA5 amp kit. Building your own amp is such a rewarding experience, and I'm sure you're going to enjoy both the process and the final product. Happy building, and I'd love to hear how your project turns out!
@@DIY_AudioGarage Hi I have built JTM45 kit from Modulus here in the UK and carefully followed the wiring diagram and switched on and there was a wining sound and by swapping the anode connections round on the EL34'S it cured the problem.
In my circuit I have used 100mfd caps through out the various points in circuit to improve the smoothing and it has helped and also the smoothing chock has been swapped out from 4mh to 10mh and can detect a smoother sound.
I have used a screened cable from jack sockets to the 1st preamp tube to cut down on noise and only earthed one end at the jack socket to avoid a earth loop.
@@itsonlyme9938 I have had the same oscillation issue before where I fixed the same way! Every time I increased the volume a bit, it would start whining. It took me a long time to figure out and almost gave up. Glad you were able to make it work. Would love to hear the tone on the amp. I’m going to try out the 100mfd cap with alligator clips to see what I can get. Thanks for sharing your experience. 🎸
Congratulations! Nice catch on that biasing snag. And your playing is fine! It shows the tone of that amp and that's what were here for! Good work!! And thanks for the share!!
Thank you!! The biasing threw me off for a second there, but I was able to fix it. I really appreciate your support!
Measuring the cathode current will also be measuring the screen current not just the anode current.
Thank you for the comment. I was following a popular biasing method I have seen on CZcams and in Rob’s site. The site also mentions other ways of biasing by measuring screen current. But I did the cathode voltage drop resistor method. It makes sense that plate plus the screen current will be measured at the cathode.
@@DIY_AudioGarage I think you just subtract 5 mA (Typical Pentode screen current) from the reading you get in the video, and that is your plate current. So a reading of 40 mA when connecting it like you do in the video will mean 35 mA plate current. Build looks great, and it sounds very quiet when it comes to hum and noise. I think I am going to get me one of these kits!
Greetings from Sweden
@@somekindofalien Absolutely right about the mA adjustment for the plate curren, your calculation nails it. Thanks for the kind words on the build and its quiet operation! Thrilled to hear you’re considering one of these kits. They're quite a rewarding project.
Good luck with your build, and I’m here if you need tips or have questions. Greetings to Sweden, and happy building!