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DIY 250W combo amp .

Jan 25, 2020
796
2,059
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Kent UK
A quick backstory behind this project . I use a Markbass 801 for rehersals with small acoustic folk band . I love it for its sound and form factor , a lot easier than schlepping a head , cab , cables etc . For outside performances that need more volume , I have been using a homemade 112 cab and TC electronics BQ250 . I though I would combine both ideas and made myself a bigger , louder combo , like the Markbass on steroids .
The Celestion BN12 - 300S 4 ohm speaker was robbed from the cabinet , and a new cabinet made . 16in cube made from 9mm ply that was laying around , laminated in parts for strength but still remarkably lightweight . Rear ported and the TC BQ250 built in . Fitted with a DI XLR socket with a ground lift wired in .
The cab was designed to be resonant at 41Hz and plugged it in this afternoon and was blown away by the volume and tone .
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17.2kg - 38lb .
Heavier than I thought but still lighter than the original cab that was all timber .
38 lbs but if you are actually getting down to the 40 Hz range then that is very cool.

I did a similar thing yrs ago. Build a stereo-style speaker with a 10" woofer and tweeter in a subwoofer wedge cabinet. Bolted a bass head to the top and had this (heavy) really full & smooth sounding practice amp for home. It was great for playing along with ... anything recorded. Forget about band usage though but that wasn't the intent.
 
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Calcs for the cabinet make it resonant at 41Hz . Theory is all well and good , but practice is better . Plugged in it sounds the mutts nuts . I will take it to a rehersal this week and see how it goes . I'll get back to you . I have high hopes for it . :D:D
 

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