College of Uproar

Most minstrels swear by the standards of respectable musicianship. However, the bards of the College of Uproar rail against those orthodoxies with the sound of rolling thunder. Raucously enthusiastic and radically transgressive, these individuals aim to disrupt the status quo with songs of unparalleled volume. 

To members of this College, the best performances are those that fully assault the senses of an audience. For this reason, the forte of these individuals lies in their ability to give voice to difficult and uncomfortable truths, as these are often the hardest truths to hear. 

Unlike other bards, those of the College of Uproar will almost always be found in the thick of a skirmish. Donned in clangorous metal armor, these bards will use their voices and instruments as deafening weapons and can electrify the battlefield with their music. 

Credit for this subclass really goes to /u/Jaekbad on Reddit. I only made a couple of tweaks so he did all the real work.

Earsplitter

When you join the College of Uproar at 3rd level, you can rock your surroundings with an improved vocal and physical toughness. You gain proficiency with medium and heavy armor, and you can now produce speech, sounds, and music up to triple their normal volume. In addition, you can use instruments you are proficient in as proficient melee weapons. 

If an instrument can be played using one or two hands, it counts as a light and versatile weapon that deals 1d6 bludgeoning damage (1d8 if wielded in two hands).

If an instrument can only be played using two hands, it counts as a two-handed weapon that deals 2d6 bludgeoning damage.

In addition, you may now use your charisma modifier for attack and damage rolls on melee attacks using your instrument and these attacks count as magical for the purpose of overcoming resistance and immunity to non-magical attacks and damage.

For 15 gold pieces worth of metal and other materials, you can fit bladed or spiked attachments to an instrument, causing it to deal slashing or piercing damage, respectively, instead of bludgeoning damage. You can plate an instrument with silver or adamantine as you could any other weapon (for their respective costs).

Sforzando

Also at 3rd level, you gain the ability to unleash a deafening, magically-amplified note using your voice or instrument. As an action, you can expend one use of your Bardic Inspiration to force all creatures in a 30-foot cone that can hear you to make a Constitution saving throw against your spell save DC. 

On a failed save, targets take thunder damage equal to two Bardic Inspiration dice and become deafened until the end of your next turn. On a successful save, targets take half this damage and are not deafened. 

The number of Bardic Inspiration dice you roll for this damage changes at certain levels in this class, increasing to three dice at 6th level, and four dice at 14th level. 

The note you emit with this feature is audible out to 300 feet and wakes any sleeping creatures in the area. 

Cacophonous Blows

At 6th level, your unbridled boisterousness endows your attacks with their own magical resonance. You gain resistance to thunder damage, and once per turn when you land a melee attack with an instrument, you can cause your hit to deal an extra 2d6 thunder damage and emit a boom audible up to 120 feet away. 

At 14th level, this extra damage increases to 4d6. 

Electrifying Solo

After reaching 14th level, your exposure to audile magics grants you immunity to the deafened condition. Further, it allows you to summon volatile thunderstorms by performing an epic vocal or instrumental solo. 

You can begin this solo using an action, and it lasts up to 1 minute. Your solo ends if you become silenced or incapacitated, if you make a melee or ranged weapon attack, or if you choose to end it on your turn (no action required by you). 

During your solo, non-allied creatures within 120 feet of you have disadvantage on their saving throws against being deafened or frightened. In addition, whenever you deal thunder damage to a creature within 120 feet of you, you can use your bonus action to deal an additional 2d12 lightning damage to it.  Additionally, allied creatures with 120 feet gain one bardic inspiration die.

Once you perform your solo, you can't perform another one until you finish a long rest.