Coolasyalike
New Member
Hi all, this is my first post so I apologise in advance for any mistakes!!
I have an old Marshall 3530 IBS amp that suffers from cut outs, despite having the amp checked out by a "pro" it still is not reliable, so I have decided to remove the pre amp section and use this with another amp to get the sound that I like and hopefully the reliability.
The problem I have is working out the best way to power just the pre amp as I want to fit it in a smaller box so I don't have to lug around a great big amp when I'm just using the tiny pre amp pcb inside? I have a schematic from the Drtube website (drtube.com/schematics/marshall/3530pre.gif and drtube.com/schematics/marshall/3530psu.gif) (which shows that the preamp is supplied with AC from the bridge rectifier ( I assume at the same 63v as stated for the amp section) but dropped over a voltage drop resistor? then I think rectified to +/- 15v DC, so should I try to supply it with the 63v AC or just bypass that and connect +/-15v DC after the rectifier circuit? and whats the best way of doing this?? I was hoping to raid Maplins for the parts if possible?? and keep everything as compact as possible, being a bass player my gear is already twice the size of the other guys and I'm not as young as I used to be! Any help or advice would be great guys anything you can chip in would be gratefully received, Cheers Guys!!
I have an old Marshall 3530 IBS amp that suffers from cut outs, despite having the amp checked out by a "pro" it still is not reliable, so I have decided to remove the pre amp section and use this with another amp to get the sound that I like and hopefully the reliability.
The problem I have is working out the best way to power just the pre amp as I want to fit it in a smaller box so I don't have to lug around a great big amp when I'm just using the tiny pre amp pcb inside? I have a schematic from the Drtube website (drtube.com/schematics/marshall/3530pre.gif and drtube.com/schematics/marshall/3530psu.gif) (which shows that the preamp is supplied with AC from the bridge rectifier ( I assume at the same 63v as stated for the amp section) but dropped over a voltage drop resistor? then I think rectified to +/- 15v DC, so should I try to supply it with the 63v AC or just bypass that and connect +/-15v DC after the rectifier circuit? and whats the best way of doing this?? I was hoping to raid Maplins for the parts if possible?? and keep everything as compact as possible, being a bass player my gear is already twice the size of the other guys and I'm not as young as I used to be! Any help or advice would be great guys anything you can chip in would be gratefully received, Cheers Guys!!
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