Do I have to pronounce the letter "l" as light or dark when there is a double "l" followed by a vowel in a word?

Question

It is known that when the letter l is followed by a vowel then it is pronounced as light, and when it is at the end of a word or is followed by a consonant then it is pronounced as dark. But it is unclear to me whether it is a dark l* or a light l* when there is a double l followed by a vowel, as in words like killer, bellicose or pullup. The Cambridge Dictionary gives this transcription the word killer: /ˈkɪl.ɚ/. As you can see there is a dot after the l in the transcription. Because of it I suppose that I should pronounce it as dark since I think it serves kind of as a consonant or indicates kind of the end of the word. Tell me please if I am right.

For those unfamiliar with Light and Dark L’s, a website says:

The L consonant sound. This sound is especially difficult for people who don’t have it in their native language. This might be because there’s actually two parts to it. It can be either a light L or a dark L. However, in the International Phonetic Alphabet, there is only one symbol that represents this sound, either a light L or a dark L. The L is light if it comes before the vowel or diphthong in the syllable. If it comes after the vowel or diphthong in a syllable, it is a dark L. First, the light L. To make this sound, the tip of the tongue reaches up, ll, ll, and touches the roof of the mouth just behind the front teeth, ll, ll, as the vocal cords are making sound. I’ve also noticed, as I’ve studied my own speech in slow motion, that sometimes I make this sound by bringing the tip of the tongue through the teeth, ll, ll, similar to the position for th, th, the TH sounds. Either position is fine, ll, like, touching the roof of the mouth, Ll, like, coming through the teeth, like the TH. Both make the same sound. That is the light L.

And now the dark L. As I said, an L is a dark L if it comes after the vowel or diphthong in a syllable, like in the word real. Dark L’s have two parts, The first is a vowel-like sound that is not written in IPA, but is certainly there. And the second is simply the same position as the light L. Lets go back to the example word, real, to talk about this. In IPA it is written with three symbols: the R, the ee vowel, and the L. But as I say it slowly, notice that there are actually four sounds. There is a sound between the ee and the ll. Rrrreeeaaalllll. It’s this third sound, this vowel-like sound that comes before the L but is not represented by a symbol in IPA. So the dark L is made up of two parts: this vowel-like sound and then the L. What is the vowel-like sound? It’s very similar to the ‘uh’ as in ‘pull’ sound.

while another website notes:

• Some accents have only Dark L : Scottish, American
• Some accents have only Light L : Welsh

Answer 1

As James K said, this doesn't have anything to do with the spelling.

Different accents of English have different patterns for the use of "dark l" vs. "light l". As you mentioned, some accents are even described as having only one of these sounds. Accents with "both" sounds are often described as actually having a "gradient" of "darker" vs. "lighter" /l/s in different environments. So this is a pretty complicated question.

In general, there seems to be a tendency for "dark l" sounds to be used more often in American accents than in British accents.

In the British "Received Pronunciation" accent of English that is often taught to learners, "light l" is used before a vowel sound, even when the /l/ comes at the end of a word or after a stressed vowel. This accent would have "light l" in "killer", "bellicose", and "pullup". (I don't know if the "light l" in "pullup" might be a bit darker than the light l used in other contexts; that sounds somewhat plausible to me.)

In certain American English accents, "dark l" is used before consonants, and also word-finally, even when a vowel follows, but "light l" is used before a vowel in most word-medial contexts. These accents would have "light l" in "bellicose", but because "pullup" is a compound, I think it might have dark l. I'm also not sure how words like ""killer" are treated in these accents.

In other American English accents (like mine), it seems that "dark l" is used whenever the /l/ is not at the start of a metrical "foot" (either as the very first sound, as in "lucky", or as an element of the onset cluster in the first syllable of the foot, as in "climbing"). So I have "dark l" in killer, bellicose and pullup because the /l/ is not at the start of a foot, but I have "light l" in words like illiterate, illuminate, crystallography, collect where the /l/ is at the start of a stressed syllable.

I quoted some sources in my answer to a related ELU question: L in the middle of a word: dark l or light l?

Answer 2

The "light" or "dark" nature of the "l" is not determined by the spelling. In a word like "killer," the "l" sound is followed by a vowel (spelled "er") and so is light. By contrast in the word "kill" (when followed by a word starting with a consonant), it is dark.

You will find in some accents "kill" is actually pronounced as "kio". They would say something that sounds like "eez gonna kio me". But this is not standard RP.

Note that the light/dark difference is phonetic, but not phonemic. Speakers of RP are not aware of a difference between light and dark "l" (though the vocalisation to "o" is usually seen as a marker of low-class speech) If you just use light "l" always you will not be misunderstood. This is also why dictionaries don't mark the difference: the same phoneme is produced differently, rather than two different phonemes existing.