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Heyboer OT for EVJ


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Does anybody know the right Heyboer OT that's a good replacement for the stock VJ OT? The current OT is giving me a horrible sound. The amp was re-tubed and still that harsh, metallic sound.


I wanna use a Heyboer because they're drop-in replacements and I heard the difference in tone is amazing. So I wanna give it a try before I give up on my VJ.


Thanks all.

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Don't give up on that amp yet! I'm not sure what that part number is, but turretboards has them. The Weber WSE15 is what I went with, and I've been very happy with it.


An OT upgrade isn't the end-all be-all for that amp, though. It will help enormously, but there are other issues with that amp that cause it under perform. The marshall mods are a massive improvement, imo. I went about mine the opposite way as you. First, I marshall modded it and got the output tube bias under control. THEN, I upgraded the transformer. THEN, I finally gutted it and did an octal build, and now run a 6ca7 in it, and haven't touched it since that conversion was done well over a year ago.


At any rate, you'll be utterly shocked at the improvement that transformer upgrade will make to the amp, even if you just do that, some fine tuning on the front end, and get the bias correct.

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Here's the one you're looking for. http://www.turretboards.com/valve_junior_page.htm#heyboer%20replacement%20OT


There are others, to be sure, but this particular Heyboer has the wiring color coded to be identical to the VJr OT's.


If you're price shopping, the Hammonds are a little cheeper. Webers are cheeper than that. MPS and Edcor are probably the least expensive. They're all good for your tone.








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I can't find a 1000uF cap at 25V

Radio Shack has them, but you'd probably feel fine with 470 or even 220uf there. It would be better to have a higher voltage rating as well, although I don't know of anyone who's seen a 25v pop. 50v or 100v would have more margin. The higher the value of capacitance here, the tighter the bottom end and the stiffer the power amp will feel.

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Alright, I'm going for the Weber as well, seems reasonable. I got another on hold but will try the Weber first.


Now, I got all the components myself along with the board and all other elements to replicate the "Marshallized" board, followed their layout to the letter, even got shocked a couple times! lol


Now, the tubes are not getting hot? What's wrong? any ideas?


Also when I removed the PCB I disconnected the brown, blue and white wires coming from the PT but they do NOT appear on the layout for the Marshallized board, so they're unhooked at the moment. Any clues where they go?



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