左邊黑屏，右邊炭屏
關於黑屏原理：https://www.effectrode.com/knowledge-base/black-plate-tubes/
黑屏唔一定好聽d，不過成本貴d
黑屏實物比炭屏深色得嚟有d令身
圓環例子
https://www.ebay.com/itm/204372657623?itmmeta=01HTMWHSXGBWBZJT7PM9V8JN3D&hash=item2f958f45d7:g:JjAAAOSwuxJkkTUF&itmprp=enc%3AAQAJAAAAwLc8c0I%2Bw8wgxYzXpOe5YhC7aXmxODkl%2F7PUx5rJviruonUGeL4isK5aS6qJ7eYwZ4AStqF4B7mv7R7paJ3Bk%2BBAlTh6f3Iz5OuHdQO4HrsjyhIeXv7lPkPQjsr5LXMf6aJmJjdAHte62y4%2F5TCezPB9XgWnWAAk%2BRQiVe%2F27MeNLLZo3ZJt9SzdTdMyq%2BH0g2dry%2FIBBatcD8hflBpCsa6r176NLxksOu%2FUNJ%2B8rqaYzGrJWKymH2o4T3XNluY%2B9A%3D%3D%7Ctkp%3ABk9SR_aex5zVYw
方環例子
https://www.ebay.com/itm/196314247794?itmmeta=01HTMWKPJ1KAZ6K2TGG189MEMG&hash=item2db53db272:g:lFcAAOSwXRtl9y0j&itmprp=enc%3AAQAJAAAA4GizvjjK2BHFrKM%2Fa6IR3IoYa7ydvBMtlYpnSQuTuIqQxnc2p%2BLSldEuV4E8WUY6foiv3o7MDUeeY8Fdku1J%2FJNto0MOL9jr8FxNXRdFf%2Fn7Aht0IbHOZlP0Qp68Y%2FKC7iq87HrMdXpc9cldpLl6K%2B3mo%2BtboyM--w8SHnBVvUo3tae3C%2FV12J5mMGYmFgfHg50mZ6uR%2BhopwSqbeLwm3v%2FPZLMY0hMKi9BfmQDRBJymwI8pnWDr6bnP1bbN3TEPoaqh3ZBTZA8hNBIuy7zQlFSIpjEZEYXqQt3azslmz6Lz%7Ctkp%3ABFBMnunOnNVj
D環例子
https://www.ebay.com/itm/196295984832?itmmeta=01HTMWMZH0ZCFG8DV0WVSC9BH4&hash=item2db42706c0:g:CfsAAOSwCPZl9My6&itmprp=enc%3AAQAJAAAA4CG18gTAeiNCZtCmY6YKeTKgX114MtaHpgDRcbZHYOqwtSDwRf%2BJCwJDJNuLRQvlzbEPsvuay1cdcw%2BiOnNfxzV3x1iTQLmaaLxkq%2BxuBsNamCz9hc1qvElECQ5VTC%2FoQRv7rlQoZmVffleGsbfPS1BW9HFpGck16SUGFf1tjluEo9zfTioa1jMqbwN6dWWvxUh8iVbDqJQ2x4V2NEJUGdwGWcP2Z8FpsELvB9Jw0TEvDa27skpYSmAzmSAmzx84i0N2xulbWSjK9aXU1k6aIbjM%2BDC569VeTSPpqpXNTU%2Bx%7Ctkp%3ABFBM3PjTnNVj
冇話邊隻環好聲d，呢d特徵只係方便去描述特定一款膽
