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Post by bluzcat on Jan 20, 2023 10:36:29 GMT -5
I have a Vox AC-15C1, and Lyle at Psionic has suggested jumping R1 on those. I would like to try it without making it permanent to see if I like the flavor first. Any thoughts? Some sort of clips I guess?
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Post by Leftee on Jan 20, 2023 11:58:08 GMT -5
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Jan 20, 2023 12:14:31 GMT -5
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Post by rdr on Jan 20, 2023 15:07:20 GMT -5
Tell us about it when you try it. I have the same amp.
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Post by bluzcat on Jan 20, 2023 22:33:03 GMT -5
Will do! I actually found where I had created a little jumper wire with alligator clips. Do you guys think the gauge matters?
When I try it, I’ll have to work myself up to get the 4.2 million screws out of the back panel!😝🤣
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Post by rdr on Jan 21, 2023 11:53:15 GMT -5
I doubt the gauge matters, likely greater than the resistor leads anyway.
An electric screwdriver is your friend.
I may also try to replace the screen grid resistors with 2 or 3 watt 1k. He implies it can be done without pulling the board (?).
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Post by bluzcat on Jan 21, 2023 16:40:51 GMT -5
I would have to check his video again. I “think” he said it could be done without pulling the board. I liked the sound of the one he modded, but I don’t need all the higher gain stuff. I’m not in love with more gain on the normal channel as I struggle to keep the amp clean when I’ve played it at volume, but I am interested in taming the brightness. That’s why I would like to try it before breaking out the soldering iron. I played it at church to help break in the Greenback for several months but just went back to my TRRI. Yes, VERY different beasts! I may be asking more of the AC-15 than it can give lol, but it is a loud 15 watts. I found it at GC on sale back in ‘18 and grabbed it long before I had heard of his or a lot of these guys channels. I am relieved to know it seems to hold up compared to others. I had a slew of vintage amps 15+ years ago, wish I had kept a couple.
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Post by bluzcat on Feb 4, 2023 12:43:29 GMT -5
I tested this yesterday and I like the result. It does bump up the gain on the clean channel, BUT, it also noticeably removed the “strident” nature of the clean channel, which sounds great. Definitely worth making more permanent when I get the chance.
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Post by rdr on Feb 17, 2023 11:55:19 GMT -5
Thanks for the info. I'll try this once I get around to figuring out why the amp buzzes loudly when turned on.
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Post by bluzcat on Feb 21, 2023 22:52:42 GMT -5
Funny you say that- mine did this today and later stopped. I have a NOS 12AX7 in V2 that I think is going bad, so hoping that’s it. Is yours constant?
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Feb 22, 2023 15:35:34 GMT -5
Thanks for the info. I'll try this once I get around to figuring out why the amp buzzes loudly when turned on. Does the buzz go off as the valves warm up, or does it carry on buzzing badly? If the latter (and you’d like some input on fixing it), please provide some further detail, eg do any controls affect it, have you tried swapping in known good valves, has an output valve shorted recently. |
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Post by rdr on Feb 23, 2023 19:28:59 GMT -5
Thanks for the offer pdf. I don't have much to report now as I haven't opened it up. But here's what I observe.
I left the amp on for about 3 days (without using the cooling fan I bought, duh). It was silent and I turned it off. Next time I turned it on, I get this loud hum, accompanied by loud, bassy percussive static. This is not affected by any control and is present with all controls at zero.
So I may open it up this weekend and inspect.
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Post by rdr on Feb 23, 2023 19:32:22 GMT -5
Oh, and it is constant and still present after warmup.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Feb 24, 2023 5:56:35 GMT -5
First step I suggest is to reseat all valves several times.
Does it pass any signal?
If so can it do loud and clean, or is it fizzly and breaks up before it gets loud?
If you get inside the chassis, try reseating all cable header a few times.
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